Crenshaw et al. Porcine Health Management (2021) 7:11 https://doi.org/10.1186/s40813-020-00180-0 RESEARCH Open Access Effect of spray-dried porcine plasma in peripartum sow feed on subsequent litter size Joe Crenshaw1* , Laura Lafoz del Río2, Luis Sanjoaquin2, Simon Tibble3, Francesc González-Solé4, David Solà-Oriol4, Carmen Rodriguez5, Joy Campbell1 and Javier Polo1,5 Abstract Background: Nutritional strategies for sows designed to reduce peripartum stress are suggested to support postpartum recovery and productivity. Spray-dried plasma (SDP) in sow feed has been reported to benefit sow and litter performance. Stressed animals fed diets with SDP have a more efficient immune response supporting animal recovery and health. The objectives of the present study using 452 sows (147 parity 1 sows, 148 parity 2 sows) were to determine if 0, 0.5 or 2.5% spray-dried porcine plasma (SDPP) in peripartum feed provided from entry in maternity through day 5 of lactation affects sow productivity and serological immune and oxidation status markers around parturition. Post-weaning sow productivity parameters including litter size at the next parturition was evaluated, but peripartum diets were only provided during the first parturition. Results: In the first parturition, total born litter size was lower (P < 0.05) especially for sows allotted to the peripartum diet with 2.5% SDPP. Percentage of stillborn pigs decreased quadratically (P < 0.05) for sows fed 0.5% or 2.5% SDPP compared to 0% SDPP in peripartum feed and this result was not affected by total born litter size. Serum glutathione peroxidase activity linearly increased (P < 0.01) with increased dietary SDPP for both prepartum and postpartum sampling periods. In the next parturition, total born pigs from combined data of parity 1 and 2 sows linearly increased (P < 0.05) and live born pigs tended (P = 0.09) to linearly increase as level of SDPP increased and this result was not affected by total born litter size in the first parturition. The change in total and live born pigs from the first to the next parturition linearly (P < 0.01) increased as dietary SDPP increased for parity 1 and 2 sows. Conclusions: The reduced percentage of stillborn pigs and increased litter size of parity 1 and 2 sows in the next parturition was independent of total born litter size in the first parturition suggesting SDPP in peripartum sow feed may have merit for reducing stillborn pigs and benefit litter size in the next parturition for parity 1 and parity 2 sows. Keywords: Cytokines, Litter size, Oxidation status, Parturition, Sows, Spray-dried porcine plasma * Correspondence: joe.crenshaw@apcproteins.com 1 APC LLC, 2425 SE Oak Tree Court, Ankeny, IA 50021, USA Full list of author information is available at the end of the article © The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Crenshaw et al. Porcine Health Management (2021) 7:11 Page 2 of 16 Background improved farrowing rate to the next litter [19–23]. Spray Most sow farms typically use a single gestation feed from dried plasma contains a diverse mixture of components breeding to entry in maternity followed by a single lacta- including albumen, globulins, peptides, growth factors, tion feed from entry in maternity to weaning to accom- and other components [18]. Research primarily using modate sow movement and management of feed mice demonstrates that SDP supplementation in feed delivery and storage capacity. Litter size has increased modulates the efficiency of the common immune sys- steadily over the past several years and the nutritional tems, including the gastrointestinal, [24–26] respiratory, needs for high-prolific sows increases, especially during [27, 28] and reproductive systems, [29, 30] and restores late gestation to support the rapidly growing fetuses and homeostasis of lymphocytes Th-1 and Th-2 balance [25] to maintain sow body condition in preparation for lacta- under an activated immune response initiated by various tion. In commercial production, daily gestation feed is types of pathogen or environmental stress. One study typically restricted, and the amount provided is adjusted [26] using weaned pigs has demonstrated 5% SDP in to control individual sow body condition. Bump feeding feed reduced diarrhea, intestinal permeability, and in- or simply increasing the daily allotted amount of gesta- flammation in intestinal tissue. More specifically, trans- tion feed during late gestation has been commonly used port stressed pregnant mice fed diets with 1, 2, 4 or 8% to provide more daily nutrient intake to support sow SDP maintained higher pregnancy rates compared to body condition and the rapidly growing foeti. The bene- control mice. Only 1 day after feeding transport stressed fits of bump feeding can be variable in commercial prac- pregnant mice diets with 1 or 8% SDP, there was a rapid tice, but most report increased sow weight and a modest restoration of Th-1/Th-2 balance in uterine tissue com- increase in pig birth weight, but an inconsistent effect pared to control mice, which had elevated pro- on pig survival [1]. Amino acid, energy concentration, inflammatory cytokines for a longer duration in early and (or) daily feed allowance in late gestation for sows pregnancy [30]. In late pregnancy, 8% dietary SDP atten- with large litter size need to be adjusted to maintain sow uated inflammation in uterine and placenta tissue and body condition and support fetal growth during late ges- reduced lethargic effects induced by injected lipopolysac- tation and throughout lactation [2–7]. Also, other stud- charide [29]. ies have demonstrated benefits from using ingredients The objectives of the present study were: 1) to deter- with high fiber content in gestation and lactation feed to mine if titrated levels of 0, 0.5% or 2.5% SDPP formu- support satiety, sow body condition and physiology, col- lated in peripartum feed affected sow productivity and ostrum production, and survival of progeny [8–11]. serology parameters around the initial parturition and 2) Parturition is often prolonged with larger litter size to determine if there were long-term effects from pro- which drains sow energy during labor and can lead to viding peripartum feed only during the initial parturition increased stillbirths, constipation, mastitis, metritis, and on post-weaning sow productivity parameters including agalactia that negatively affects postpartum uterine re- litter size of the next parturition. covery, and subsequent milk production, progeny sur- vival and growth [12–16]. A peripartum or transition Materials and methods feed should be considered to provide nutrients and in- Animal care statement gredients that address needs for the prolific sow in late The experiment was done at a commercial sow farm gestation to help mitigate early postpartum stress and that fulfilled animal housing standards and management prepare the sow for ad libitum consumption of lactation by farm animal caretakers, trained to abide by authorita- feed to support milk production, progeny growth and tive animal welfare standards established by the Law on survival, and subsequent sow reproductive performance. Animal Welfare 2/2008 published by Diari Oficial de la This targeted application of peripartum feed should be Generalitat Catalunya [31]. provided to sows as they are moved to maternity and continued for a few days after parturition to facilitate the Animals and housing management and logistics associated with sow move- The study was conducted at a commercial farm in Spain ment, feed delivery and storage at the maternity facility. with 2000 sows. Maternity rooms were mechanically Spray dried animal plasma (SDP) of porcine (SDPP) or ventilated with high-flow fans and individual room bovine origin (SDBP) has been used in nursery pig diets temperature control. There were 27 maternity rooms, because of its benefits on post-weaning growth, feed in- each with 16 crates. Each crate had individual sow take, morbidity, and survival [17, 18]. Sows fed SDP in feeders equipped with feed drop tubes and drinkers and lactation feed had several improvements in productivity supplemental heat pads for the piglets. At this farm sows measures including higher feed intake for young sows, were farrowed naturally. There were 452 Naïma Choice heavier litter and average pig weight at weaning, im- Genetics sows (average parity 2.63 ± 0.08; parity 1 to 8) proved pig survival, reduced wean to estrus interval, and used for the study that had their initial parturition from Crenshaw et al. Porcine Health Management (2021) 7:11 Page 3 of 16 Table 1 Number of sows per diet, parity, and sow group during weaning, sow mortality and culls prior to movement to the initial and next parturition breeding, percentage of sows moved to breeding, the in- Parity and number of sows at initial parturitiona Allb Yc Md tervals for wean-to-first-estrus (date of first estrus minus Diete 1 2 3 4 5 6 7 8 1–8 1–2 3–8 date of weaning) and wean-to-final-service (date of final 0 47 47 11 10 14 16 2 0 147 94 53 service minus date of weaning), percentage of sows com- pleting their next parturition, and litter size at birth of 0.5 55 56 9 17 15 7 6 2 167 111 56 the next parturition. In addition the change in total and 2.5 45 45 11 12 14 5 6 0 138 90 48 live born litter size from the initial to next parturition Sum 147 148 31 39 43 28 14 2 452 295 157 was calculated, considering total born litter size of the Parity and number of sows at next parturitionf All Y M initial parturition was established before peripartum di- Diet 1 2 3 4 5 6 7 8 1–8 1–2 3–8 ets were fed. Post-weaning sow reproductive perform- 0 45 42 11 10 13 15 2 0 138 87 51 ance and litter size information at birth for the next parturition was recorded to determine if prior feeding of 0.5 50 53 9 15 14 7 5 2 155 103 52 the peripartum feed in the initial parturition impacted 2.5 43 42 11 12 14 5 6 0 133 85 48 subsequent litter size in the next parturition. Sum 138 137 31 37 41 27 13 2 426 275 151 a Sow parity during initial parturition. Parity 1 is defined as a gilt having her Experimental peripartum sow diets first litter b All sows regardless of parity were used for group All statistical analysis Three peripartum sow diets containing either 0, 0.5 or c Only parity 1 and 2 sows were used for group Y (young sows) 2.5% SDPP were formulated to provide similar levels of statistical analysis net energy and amino acids. Soybean meal was the pri- d Only parity 3 to 8 sows were used for group M (mature sows) statistical analysis mary protein source replaced by 2.5% SDPP (Table 2). e Diet is peripartum dietary treatment containing 0, 0.5 or 2.5% spray dried Sows were provided 3 kg/d of their assigned peripartum porcine plasma that was fed only during the initial parturition from entry in maternity through day 5 of lactation feed pellets from the day of entry in maternity to the day f Original sow parity at initial parturition and number of sows that had their of parturition (average 6.1 days), and 4.5 kg/d from day 1 next parturition to 5 of lactation. Peripartum feed output and refusals were recorded during the peripartum period. Average November 2018 through March 2019 and the average days of the peripartum period and average daily feed in- age of pigs at weaning was 24.3 ± 0.23 d. Sows were take per sow corrected for feed refusals are presented in managed using a continuous flow through maternity Table 3. Sows were provided a common lactation feed rooms, thus requiring a rolling random allotment of for the remainder of the lactation period to weaning and sows to peripartum diets with an attempt to balance common breeding-gestation feed to the next parturition, diet allotment as evenly as possible across sow parity as however feed consumption per sow was not recorded they entered maternity. Table 1 shows the number of during these production periods. The standard feeding sows per parity and diet after all sows had been allotted practice for lactating sows at this farm was to gradually in the study. increase feed to ad libitum intake by day 7 of lactation Standard production parameters, including litter size and continue providing feed ad libitum to weaning. Lac- of total pigs born, pigs born alive, stillborn pigs, mum- tation feed was provided 3 times per day to provide ad mified pigs, pigs after cross-fostering, and pigs weaned libitum intake. During the first month of pregnancy, were recorded for the initial parturition. According to sows in good body condition at weaning were provided the study protocol, cross-fostering of litters during the 2.2 to 2.4 kg of gestation feed per day, while thin sows initial parturition was only to be done within 48 h post- were provided 3.0 to 3.5 kg per day. After the first partum and only within room and within dietary treat- month of pregnancy, all sows were provided 2.4 kg of ment. However, cross-fostering was not successfully gestation feed per day. The gestation feed was provided accomplished as requested due to the difficulty to man- once daily. age piglet welfare yet maintain litter integrity within treatment groups throughout the lactation period at this Blood sampling and analytical procedures highly prolific sow farm. Therefore, progeny data after Two sampling times (2 days before expected parturition cross-fostering to weaning was excluded from the final at 115 days of gestation and 4 days after parturition) data analyses due to these uncontrollable, but confound- were used for collection of blood from 57 randomly se- ing factors that make it difficult to manage sow studies, lected sows. Twenty-one sows were sampled twice and especially when having more than two dietary 36 once (either before or after parturition). Overall, a treatments. total of 78 samples were collected and 6 were discarded Other parameters evaluated included ultrasonic back- due to hemolysis. The final number of sows and ana- fat depth of sows at the day of entry to maternity and at lyzed samples per diet are presented in Table 7. Blood Crenshaw et al. Porcine Health Management (2021) 7:11 Page 4 of 16 Table 2 Ingredient and nutrient composition of peripartum sow diets Ingredient, % 0% SDPP 0.5% SDPP 2.5% SDPP Barley 31.61 30.77 30.35 Corn 15.00 15.00 15.00 Wheat 10.00 10.00 14.00 Wheat bran 20.00 20.00 20.00 Soybean meal (47% CP) 10.30 10.70 5.70 Spray-dried porcine plasmaa 0.00 0.50 2.50 b Ligno-cellulose product 2.50 2.50 2.50 Beet pulp 7.50 7.50 7.50 Soy oil 0.60 0.63 0.20 Calcium carbonate 1.65 1.70 1.70 Monocalcium phosphate 0.04 0.00 0.00 Salt 0.44 0.40 0.25 L-lysine HCL 0.05 0.00 0.00 L-threonine 0.015 0.00 0.00 VTM premixc 0.30 0.30 0.30 Analyzed nutrients Dry matter, % 87.2 87.3 87.9 Crude protein, % 14.4 15.2 14.6 Calculated net energy, kcal/kg 2101 2100 2100 Calcium, % 0.90 1.04 1.03 Phosphorus, % 0.43 0.45 0.46 Calculated digestible phosphorus, % 0.25 0.25 0.25 Lysine, % 0.65 0.67 0.69 Methionine, % 0.23 0.22 0.22 Methionine + Cysteine, % 0.44 0.44 0.47 Threonine, % 0.56 0.53 0.57 Tryptophan, % 0.19 0.20 0.19 Isoleucine, % 0.59 0.61 0.57 Valine, % 0.64 0.68 0.68 a APPETEIN GS, APC Europe S.L., Granollers, Spain b FibreCell 5, Agromed Austria GmbH, Kremsmünster, Austria. Ligno-cellulose product made from wood c ASN GESTATING SOWS 3 FIT; a commercial vitamin-trace mineral premix plus phytase. Provided the following per kg: vitamin A, 8500 UI; vitamin D3, 1500 UI; vitamin E, 30 total; vitamin E, 15 UI; moliphenol, 3 g, vitamin K3, 2 g; vitamin B1, 1.5 g; vitamin B2, 3 g; vitamin B6, 2 g; vitamin B12, 20 mg; pantothenic acid, 10 g; niacin, 15 g; folic acid, 2 g; biotin, 200 mg; choline, 300 g; Fe, 80 g; Cu, 10 g; Zn, 90 g; Mn, 60 g; selenium total, 0.25 g; organic selenium, 0.1; iodine, 2 g; phytase 750 samples were collected from the tail vein using open V, Hertogenbosch, The Netherlands) as specified by the bleeding into vacutainer tubes without anticoagulant. manufacturer: interferon alpha (IFN-α), interferon Blood samples were kept at ambient temperature for 30 gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), to 45 min until clot formation, then subjected to centri- interleukin (IL), IL-1β, IL-4, IL-6, IL-8, IL-10 and IL-12. fugation at 2000 g for 10 min. The serum was pipetted Readings were performed on the Luminex MAGPIX sys- into new tubes, labeled by date and sow number, then tem (Luminex B. V, Hertogenbosch, The Netherlands). stored at − 80 °C until analysis for cytokine and oxida- Total antioxidant status (TAS), superoxide dismutase tion status parameters. Serum samples were analyzed by (SOD) and glutathione peroxidase (GPx) activities were the Animal Nutrition and Welfare Service (SNIBA), De- determined using a kit from RANDOX laboratories partment of Animal Food Science Department, Universi- (Crumlin, UK) and readings were performed using an tat Autonóma de Barcelona. AU400 analyzer (Beckman Coulter, Germany). Malonal- Cytokine serum levels were determined using a cyto- dehyde (MDA) levels were determined using a TBARS kine and chemokine panel (ProcartaPlex Pig, Luminex B. Assay Kit (Cayman Chemical, Michigan, USA) following Crenshaw et al. Porcine Health Management (2021) 7:11 Page 5 of 16 Table 3 Peripartum feed intake, backfat and postweaning reproductive performance of sows fed peripartum diets Peripartum diet, % SDPPb Statistics (F-test, P =)c a Variable Group 0 0.5 2.5 SEM PR D L Q INT Sows, n All 147 167 138 – – – – – – Y 94 111 90 – – – – – – M 53 56 48 – – – – – – Entry to farrow days All 5.95 6.42 6.11 0.19 0.03 0.17 0.97 0.06 0.03 Y 5.46 6.02 6.29 0.25 0.31 0.05 0.04 0.19 0.24 M 6.43 6.89 5.93 0.30 0.39 0.03 0.06 0.10 0.18 Total days diets fed All 10.95 11.42 11.11 0.19 0.03 0.17 0.97 0.06 0.03 Y 10.46 11.02 11.29 0.25 0.31 0.05 0.04 0.19 0.24 M 11.43 11.89 10.93 0.30 0.39 0.03 0.06 0.10 0.18 d Feed intake, kg/d All 3.77 3.76 3.77 0.09 < 0.01 0.67 0.70 0.42 0.25 Y 3.76 3.75 3.76 0.10 0.24 0.32 0.56 0.17 0.14 M 3.68 3.64 3.70 0.02 0.45 0.02 0.09 0.06 0.14 Entry backfat, mm All 13.91 13.38 13.46 0.30 0.67 0.37 0.46 0.23 0.16 Y 13.53 13.75 13.23 0.35 < 0.01 0.55 0.39 0.51 0.22 M 13.39 13.04 13.62 0.60 0.09 0.71 0.61 0.56 0.39 e Wean backfat, mm All 10.33 9.82 10.26 0.24 < 0.01 0.23 0.74 0.09 0.24 Y 9.43 9.51 9.50 0.30 < 0.01 0.97 0.89 0.84 0.16 M 10.65 10.17 10.89 0.53 0.38 0.49 0.50 0.37 0.58 Backfat loss, mme All −3.73 −3.56 −3.36 0.31 < 0.01 0.48 0.25 0.73 0.86 Y −4.04 −4.02 −3.67 0.37 0.04 0.57 0.29 0.88 0.48 M −2.79 −2.95 −2.78 0.44 0.10 0.91 0.88 0.71 0.51 Sows to breeding, % All 94.4 92.8 97.8 2.05 0.23 0.20 0.12 0.37 0.69 Y 92.6 92.8 95.6 2.60 0.76 0.65 0.36 0.90 0.34 M 97.3 93.8 100.0 3.55 0.88 0.32 0.34 0.32 0.87 Wean-to-first-estrus, d All 8.63 8.65 8.96 0.64 0.92 0.92 0.68 0.96 0.36 Y 8.47 8.04 9.59 0.84 0.15 0.38 0.22 0.53 0.26 M 9.83 8.96 8.51 0.98 0.23 0.59 0.34 0.59 0.03 Wean-to-final-service, d All 11.43 10.97 10.69 1.00 0.88 0.87 0.64 0.80 0.76 Y 10.77 10.84 11.14 1.27 0.23 0.98 0.82 0.99 0.03 M 12.63 10.86 10.02 1.73 0.53 0.51 0.30 0.53 0.52 a Results for group All included data of all sows, group Y included data only for young (parity 1 and parity 2) sows and group M included data only for mature sows (parity 3 to 8) b Values are least squares means (LSM) and the pooled standard error of the mean (SEM) for peripartum diets by sow group c Each sow group was analyzed using a mixed model for the effects of PR (sow parity), D (peripartum diet), L (linear contrast of % SDPP in diet), Q (quadratic contrast of % SDPP in diet) and INT (interaction of parity and diet) d Included the covariance of total days the peripartum diet was fed in the mixed model for the All and Y sow group e Included the covariance of days from entry to weaning in the mixed model the manufacturer protocol and readings were performed procedure of SAS (Statistical Analysis System, version using the Multiskan Sky (ThermoFisher Scientific, Wal- 9.4, SAS Inst. Inc., Cary, NC). Linear (L) and quadratic tham, MA, USA). (Q) contrasts were included in the model to test the sig- nificance of SDPP level used in the peripartum diet. A Statistical analysis covariant was included in the mixed model for some All production data with sow as the experimental unit variables to further evaluate the significance of diet or were statistically analyzed for the effects of sow parity, diet and parity interactions. The least squares mean peripartum diet, and interaction of parity and peripar- (LSM) and pooled standard error of the mean (SEM) for tum diet (INT) using a mixed model (PROC MIXED) diet effects are reported. In addition, Pearson correlation Crenshaw et al. Porcine Health Management (2021) 7:11 Page 6 of 16 coefficients (r) and T-test probability for select variables second parturition was included in the model for the were determined using the PROC CORR procedure of number and percentage of stillborn and mummified pigs SAS. (Table 5). Pearson correlation coefficients for select litter Parity of sows used in this study ranged from 1 to 8 size variables are presented in Table 6. with parity 1 defined as a gilt having her first litter. Serology results were analyzed using a mixed model However, parity distribution across dietary treatments procedure (PROC MIXED) of SAS for the effects of was not evenly distributed, especially for parity 3 to 8 sampling period (2 days before expected parturition at sows which represented only about 35% of the sows in 115 days of gestation and 4 days after parturition), peri- the study (Table 1). Unequal parity distribution across partum diet (0, 0.5 and 2.5% SDPP), and the interaction dietary treatments can significantly skew calculated LSM of sampling period and peripartum diet. The LSM and when using sow parity in the model. Therefore, due to SEM for peripartum diet by sampling period for cytokine the unequal diet by parity distribution, parity 1 (n = 147) and oxidation status markers are presented in Table 7. and parity 2 sows (n = 148 sows) were designated as par- Pearson correlation coefficients of serological variables ity group Y (n = 295) and parity 3 to 8 sows (n = 151 with litter size variables are presented in Table 8. total sows) were designated as parity group M to in- Differences in results were considered significant at crease the statistical power of a F-test to detect potential P < 0.05 and a tendency for differences in results are re- effects of diet, parity group, and interactions of diet and ported for probabilities between P > 0.05 and P < 0.10. parity group on economically important variables such as litter size. A post hoc calculated sample size of 291 Results was estimated for detecting a 0.4 difference in a fixed ef- Production data results fect using a power calculator (G*Power 3.1.2; https:// Results of peripartum feed intake, sow backfat depth and gpower.software.informer.com/3.1/) for the above model postweaning sow performance variables by peripartum of fixed effects and interactions using a F-test (P = 0.05). diet and sow group are presented in Table 3. Using all The designated parity Y or M group was used in the sows, the average days from entry in maternity to the statistical model to test the significance of these desig- day of the initial parturition differed for the effect of par- nated parity groups, diet, and the interaction of desig- ity and the interaction of diet and parity, with a quad- nated parity group and diet for all sows. Furthermore, ratic tendency (P = 0.06) for SDPP level in the diet. In due to detection of the designated parity group and diet the Y group, entry to farrow days was significant for diet interactions for some of the litter size variables, datasets and increased linearly with level of SDPP in the diet. For using only the group Y sows or the group M sows were the M group the effect of diet was significant and tended analyzed separately so that the original parity of the sows (P = 0.06) to increase linearly with SDPP level in the diet. within each subset of data could be evaluated using the The average days of the peripartum feeding period for mixed model with the actual parity, diet, and interaction the All, Y and M sow groups presented the same parity, of parity and diet. diet, or parity and diet interaction significant differences In Tables 3, 4 and 5 production data results of all sows or trends as for the average days from entry to are listed under group All. Results of the combined par- farrowing. ity 1 and 2 sows are listed under group Y with select var- The covariance of total peripartum feed days was in- iables also showing the LSM of the interaction of diet cluded in the model for each sow group to evaluate dif- and parity by parity 1 (P1) or parity 2 (P2) sows. Results ferences in average daily peripartum feed intake from the combined data of parity 3 to 8 sows are listed corrected for feed refusals. For all sows, parity differed, under group M. The covariance of total days the peri- but there were no significant effects of diet or inter- partum diets were fed was included in the model for action of diet and parity for peripartum feed intake. average daily feed intake of the diets, and the days from There were no differences of parity, diet, or the inter- entry in maternity to weaning was included in the model action of parity and diet for the Y group. When using for backfat depth loss and backfat depth at weaning total peripartum feed days in the model for the M sow (Table 3). In Table 4, the model to evaluate total born group, the convergence criteria for this covariant could litter size at the first parturition included the covariance not be met, therefore it was excluded from the model to of sow age at the initial parturition for the Y group of evaluate feed intake for the mature sow group. Feed in- sows. Also, in Table 4 the total born litter size at the take for the M group of sows was significant for diet first parturition was included in the model for the num- with a quadratic tendency (P = 0.06) for SDPP level with ber and percentage of stillborn and mummified pigs. 0.5% SDPP having the lower feed intake. The covariance of total born litter size of the first par- Average backfat depth at weaning and backfat loss turition was used in the model for total born in the sec- from entry to weaning were evaluated with the covari- ond parturition, and the covariance of total born in the ance of days from entry in maternity to weaning Crenshaw et al. Porcine Health Management (2021) 7:11 Page 7 of 16 Table 4 Litter size during the first parturition by sow group and peripartum diet Peripartum diet, % SDPPb Statistics (F-test, P =)c a Variable Group 0 0.5 2.5 SEM PR D L Q INT Sows, n All 147 167 138 – – – – – – Y 94 111 90 – – – – – – P1 47 55 45 – – – – – – P2 47 56 45 – – – – – – M 53 56 48 – – – – – – d Total born pigs All 14.68 14.69 13.82 0.30 < 0.01 0.06 0.02 0.62 0.42 Y 14.23 14.10 12.83 0.36 0.11 < 0.01 < 0.01 0.73 0.33 P1 13.65 14.17 12.37 0.50 P2 14.81 14.02 13.29 0.50 M 15.10 15.29 15.00 0.64 0.59 0.93 0.82 0.78 0.42 Live born pigs All 12.65 13.12 12.28 0.29 0.07 0.10 0.14 0.12 0.16 Y 12.68 12.93 11.56 0.34 0.02 < 0.01 < 0.01 0.26 0.21 P1 11.83 12.89 11.13 0.49 P2 13.53 12.96 11.98 0.49 M 12.76 13.37 13.13 0.58 0.41 0.72 0.80 0.43 0.55 e Stillborn pigs All 1.84 1.40 1.34 0.17 < 0.01 0.06 0.08 0.09 0.71 Y 1.41 1.05 1.16 0.18 0.18 0.22 0.49 0.10 0.25 P1 1.72 1.16 1.09 0.24 P2 1.11 0.93 1.22 0.24 M 2.07 1.61 1.59 0.43 0.84 0.65 0.50 0.46 0.71 Stillborn, %e All 11.78 8.77 9.29 1.01 0.03 0.06 0.23 0.04 0.46 Y 9.98 7.04 9.04 1.14 0.20 0.14 0.98 0.04 0.12 P1 12.25 8.19 8.05 1.61 P2 7.71 5.88 10.04 1.61 M 12.83 9.98 9.78 2.25 0.73 0.53 0.41 0.38 0.82 e Mummies All 0.19 0.17 0.21 0.05 0.02 0.87 0.75 0.67 0.92 Y 0.11 0.11 0.14 0.05 0.66 0.84 0.56 0.92 0.57 M 0.26 0.31 0.28 0.14 0.29 0.96 0.99 0.77 0.54 Mummified, %e All 1.22 1.11 1.46 0.39 0.07 0.80 0.56 0.74 0.94 Y 0.75 0.68 1.18 0.44 0.44 0.66 0.40 0.76 0.30 M 1.58 2.13 1.82 0.87 0.28 0.88 0.96 0.61 0.36 a Results for group All included data of all sows, group Y included data only for young (parity 1 and parity 2) sows and group M included data only for mature sows (parity 3 to 8) b Values are least squares means (LSM) and pooled standard error of the mean (SEM) for peripartum diets by sow group. The interaction of diet and parity LSM and SEM are shown for some variables in the Y group as P1 (parity 1 sows) or P2 (parity 2 sows) c Each sow group was analyzed using a mixed model for the effects of PR (sow parity), D (peripartum diet), L (linear contrast of % SDPP in diet), Q (quadratic contrast of % SDPP in diet) and INT (interaction of parity and diet) d Included the covariance of sow age at the initial parturition in the mixed model used for Y group sows only e Included the covariance of total born pigs in the mixed model for each sow group (30.42 ± 0.09) in the model (Table 3). There were no sig- depth at entry for the Y group and differed for backfat nificant effects of diet or interaction of parity and diet depth at weaning and for backfat loss from entry to for average backfat depth at entry, at weaning, or for weaning for the All and Y group of sows. backfat loss from entry to weaning for each of the sow During the initial parturition which used 452 sows, 20 groups, with the exception that there was a downward died and 5 were culled postweaning. There were no sig- quadratic trend (P = 0.09) for sows fed 0.5% SDPP to nificant effects of parity or diet on the percentage of have a lower backfat depth at weaning in the All sow sows that were moved to breeding for any of the sow group. The effect of parity differed (P < 0.05) for backfat groups. One serviced sow previously fed the peripartum Crenshaw et al. Porcine Health Management (2021) 7:11 Page 8 of 16 Table 5 Litter size of sows that farrowed a second litter by sow group and diet Peripartum diet, % SDPPb Statistics (F-test, P =)c a Variable Group 0 0.5 2.5 SEM PR D L Q INT Sows, n All 138 155 133 – – – – – – Y 87 103 85 – – – – – – P1 45 50 43 – – – – – – P2 42 53 42 – – – – – – M 51 52 48 – – – – – – d Total born pigs All 14.17 14.42 14.46 0.34 < 0.01 0.75 0.56 0.61 0.03 Y 14.14 15.09 15.49 0.36 0.11 0.02 0.02 0.12 0.82 P1 13.78 14.94 15.05 0.50 P2 14.50 15.25 15.93 0.51 M 14.46 13.50 13.32 0.56 < 0.01 0.26 0.19 0.25 0.50 Live born pigs All 12.85 12.92 13.08 0.30 < 0.01 0.86 0.58 0.94 0.21 Y 13.02 13.55 13.97 0.36 0.36 0.18 0.09 0.44 0.72 P1 12.80 13.58 13.60 0.51 P2 13.24 13.53 14.33 0.52 M 13.05 11.99 11.83 0.55 < 0.01 0.20 0.16 0.20 0.79 e Stillborn pigs All 0.96 1.24 0.98 0.13 0.19 0.09 0.55 0.03 0.54 Y 0.78 1.17 1.00 0.13 0.17 0.06 0.53 0.02 0.84 M 0.96 1.14 1.01 0.22 0.20 0.78 0.97 0.48 0.13 Stillborn, %e All 6.81 8.05 6.93 0.74 0.16 0.40 0.75 0.19 0.87 Y 6.06 7.83 7.09 0.98 0.37 0.32 0.69 0.14 0.57 M 6.76 7.94 7.79 1.53 0.09 0.82 0.71 0.58 0.32 e Mummified pigs All 0.44 0.40 0.49 0.05 0.66 0.44 0.33 0.41 0.14 Y 0.37 0.40 0.54 0.06 0.26 0.09 0.03 0.99 0.42 M 0.45 0.37 0.48 0.10 0.40 0.60 0.60 0.43 0.43 Mummified, %e All 3.01 2.73 3.61 0.36 0.21 0.20 0.12 0.37 0.37 Y 2.38 2.71 3.55 0.42 0.26 0.12 0.04 0.86 0.35 M 3.10 2.64 4.24 0.80 0.54 0.22 0.15 0.45 0.31 Total born change f All −0.53 −0.30 0.61 0.42 < 0.01 0.13 0.04 0.99 0.05 Y −0.13 1.01 2.45 0.51 0.76 < 0.01 < 0.01 0.32 0.93 P1 0.07 0.96 2.56 0.72 P2 −0.33 1.06 2.33 0.72 M −0.70 − 2.03 −1.68 0.86 0.05 0.48 0.57 0.25 0.83 Live born changef All 0.16 −0.31 0.68 0.41 < 0.01 0.22 0.18 0.26 0.06 Y 0.26 0.66 2.17 0.50 0.26 0.02 < 0.01 0.96 0.79 P1 0.84 0.88 2.33 0.71 P2 −0.33 0.45 2.02 0.71 M 0.27 −1.58 −1.31 0.82 0.04 0.19 0.30 0.11 0.95 a Results for group All included data of all sows, group Y included data only for young (parity 1 and parity 2) sows and group M included data only for mature sows (parity 3 to 8). The interaction of diet and parity LSM and SEM are shown for some variables in the Y group as P1 (parity 1 sows) or P2 (parity 2 sows) b Values are least squares means (LSM) and pooled standard error of the mean (SEM) for peripartum diets by sow group c Each sow group was analyzed using a mixed model for the effects of PR (sow parity), D (peripartum diet), L (linear contrast of % SDPP in diet), Q (quadratic contrast of % SDPP in diet) and INT (interaction of parity and diet) d Included the covariance of total born pigs of the initial parturition in the mixed model used for each sow group e Included the covariance of total born pigs of the next parturition in the mixed model for each sow group f Total born change is total born litter size of subsequent parturition minus total born litter size of previous parturition. Live born change is live born litter size of subsequent parturition minus live born litter size of previous parturition Crenshaw et al. Porcine Health Management (2021) 7:11 Page 9 of 16 Table 6 Correlation coefficients for select variables related to litter size by sow group First parturition Second parturition Total borna Total bornb Variable Group c r P= n Variable Group r P= n Stillborna, n All 0.3698 < 0.0001 452 Stillbornb, n All 0.1746 0.0003 426 M 0.4577 < 0.0001 157 M 0.2739 0.0007 151 Y 0.2746 < 0.0001 295 Y 0.1329 0.0276 275 Dietd 0 0.3020 0.0031 94 Diet d 0 −0.0296 0.7857 87 0.5 0.3212 0.0006 111 0.5 0.2306 0.0191 103 2.5 0.1881 0.0758 90 2.5 0.0842 0.4437 85 Sow agea Y 0.0909 0.1216 295 Sow ageb Y 0.0914 0.1306 275 d d Diet 0 0.1755 0.0906 94 Diet 0 0.0893 0.4107 87 0.5 −0.0013 0.9889 111 0.5 0.0572 0.5658 103 2.5 0.1150 0.2806 90 2.5 0.1512 0.1673 85 Total bornb All −0.0356 0.4635 426 M −0.0020 0.9808 151 Y −0.0129 0.8314 275 d Diet 0 0.0194 0.8588 87 0.5 −0.1419 0.1527 103 2.5 0.1589 0.1462 85 a Designates variable of the first parturition b Designates variable of the second parturition c Values are Pearson correlation (r) coefficients, T-test probability (P) and number (n) of sows per groups All (all sows), Y (parity 1 and 2 sows) and M (parity 3 to 8 sows) during initial and next parturition d Values are r, P, and n by diet containing 0, 0.5 or 2.5% SDPP within the Y group of sows diet with 0% SDPP in the first parturition failed to far- level of SDPP in the diet. The total born litter size for row the next litter. the Y group of sows was evaluated using the covariance Average wean-to-first-estrus interval and average of sow age in the model, however sow age did not wean-to-final-service interval did not significantly differ change the significance of the differences for the diet ef- by diet or parity for the All sow group, however there fect. The correlation coefficient (r = 0.0909) was low be- was a significant parity by diet interaction for wean-to- tween sow age and total born litter size of the Y sow first-estrus interval for the M sow group and a signifi- group (Table 6). cant parity by diet interaction for wean-to-final-service There was a tendency (P = 0.07) for an effect of parity interval for the Y sow group. on live born pigs for the All sow group. Live born pigs The results for litter size variables during the first par- per litter in the Y group was significant by parity, diet, turition by sow group and peripartum diet are presented and presented a linear reduction in litter size as SDPP in Table 4. When analyzing data from all sows, there level increased. There were no significant effects of par- was a significant effect of parity and a significant linear ity or diet for live born pigs in the M sow group. effect of diet for total born pigs per litter (sum of still- The model used to analyze the number of stillborn born, mummified, and live born pigs) for sows allotted and mummified pigs included total born pigs per litter to the 2.5% SDPP diet, which had the lowest number of due to the allotment differences in total born by diet. total born pigs per litter. The linear effect of SDPP level The number of stillborn pigs per litter differed by parity in the peripartum diet for total born pigs per litter was with a downward linear tendency (P = 0.06) as SDPP also significant for the Y group of sows but did not differ level increased in peripartum diets for the all sow group. for the M group of sows. The farm was able to provide There were no significant parity or diet effects on num- records for the age of the parity 1 and 2 sows at the ini- ber of stillborn pigs for Y or M group sows, however tial parturition to evaluate if sow age was a factor associ- there was a tendency (P = 0.10) for a downward quad- ated with the variable total born litter size by allotted ratic response to increasing dietary SDPP in the Y group diet. Average sow age at the initial parturition for parity of sows. Within the Y group of sows there was an indi- 1 sows was 51.5, 51.1 and 51.0 weeks and 72.1, 71.8 and cation (P = 0.12) of a parity and diet interaction; parity 1 71.8 weeks for parity 2 sows per respective increasing sows presented a pattern of decline in number of Crenshaw et al. Porcine Health Management (2021) 7:11 Page 10 of 16 Table 7 Serum cytokine and oxidation status of prepartum and postpartum sows fed peripartum diets with SDPP Peripartum diet, % SDPPa Statistics (F-test, P =)b Variable Period 0 0.5 2.5 SEM SP D L Q INT Sows, nc −2 d 11 13 11 – – – – – – +4 d 14 9 14 – – – – – – IFN-α, pg/mL −2 d 0.97 (10) 0.49 (9) 0.58 (9) 0.38 0.80 0.17 0.30 0.14 0.88 +4 d 1.27 (13) 0.45 (6) 0.55 (11) 0.47 IFN-γ, pg/mL −2 d 1.67 (10) 1.60 (9) 1.69 (9) 0.06 0.73 0.72 0.86 0.44 0.63 +4 d 1.71 (13) 1.67 (6) 1.63 (12) 0.08 IL-10, pg/mL −2 d 3.16 (10) 3.43 (9) 3.45 (9) 1.79 0.25 0.70 0.52 0.63 0.81 +4 d 3.61 (13) 5.51 (6) 5.95 (12) 2.20 IL-1β, pg/mL −2 d 82.7 (10) 24.5 (9) 8.98 (9) 45.2 0.88 0.23 0.18 0.35 0.99 +4 d 82.1 (13) 31.6 (6) 18.9 (12) 55.4 IL-4, pg/mL −2 d 1.68 (10) 1.30 (9) 1.25 (9) 0.29 0.81 0.19 0.18 0.27 0.99 +4 d 1.77 (13) 1.36 (6) 1.28 (12) 0.35 IL-6, pg/mL −2 d 32.5 (10) 15.6 (9) 8.46 (9) 14.1 0.81 0.24 0.25 0.26 0.91 +4 d 28.5 (13) 7.36 (6) 12.6 (12) 17.2 IL-8, pg/mL −2 d 26.0 (10) 27.9 (9) 13.5 (9) 15.0 < 0.01 0.35 0.21 0.38 0.84 +4 d 60.6 (13) 78.7 (6) 48.5 (12) 18.4 TNF-α, pg/mL −2 d 31.0 (10) 44.6 (9) 19.9 (9) 18.4 0.50 0.83 0.55 0.86 0.72 +4 d 47.9 (13) 36.8 (6) 41.3 (12) 22.5 IL-12, pg/mL −2 d 146.2 (10) 89.9 (9) 63.9 (9) 33.5 0.91 0.15 0.22 0.17 0.59 +4 d 122.6 (13) 69.4 (6) 98.9 (12) 41.1 MDA, μM −2 d 13.4 (11) 11.2 (13) 12.2 (11) 2.48 < 0.01 0.61 0.49 0.46 0.66 +4 d 17.7 (12) 16.8 (8) 20.8 (13) 2.91 SOD, U/mL −2 d 0.97 (11) 0.62 (13) 0.75 (11) 0.15 0.07 0.12 0.20 0.11 0.75 +4 d 1.17 (14) 0.97 (8) 0.87 (12) 0.18 TAS, mmole/L −2 d 0.47 (10) 0.61 (13) 0.65 (11) 0.07 0.57 0.15 0.13 0.23 0.66 +4 d 0.56 (11) 0.63 (6) 0.63 (13) 0.09 GPx, U/L −2 d 7382 (11) 8188 (13) 9055 (11) 496 0.92 0.01 < 0.01 0.28 0.87 +4 d 7599 (14) 8340 (9) 8806 (14) 548 a Values are least squares diet means, pooled standard error of the mean (SEM) and number (n) of serum samples analyzed by sampling period, 2 d before expected parturition at day 115 of gestation (−2 d) and 4 d after parturition (+ 4 d) b Probability values for SP (sampling period), D (diet), L (linear contrast of % SDPP in diet), Q (quadratic contrast of % SDPP in diet), and INT (interaction of SP and D) c Number of sows sampled by period and diet; number of samples analyzed per cytokine or oxidation status marker varied due to discarded samples affected by hemolysis stillborn pigs with increasing SDPP level, while parity 2 sow group there were no significant effects of parity or sows presented a quadratic pattern to SDPP level with diet for percentage of stillborn pigs. parity 2 sows fed 0.5% SDPP having the lowest average Mummified pigs per litter significantly differed by par- number of stillborn pigs. ity and mummified pigs as a percentage of total born When stillborn pigs were expressed as a percentage of tended (P = 0.07) to differ by parity for the All sow total born pigs in the All sow group, there were signifi- group, however there were no significant effects of parity cant effects of parity, and a quadratic reduction of per- or diet for number or percentage of mummified pigs per cent stillborn pigs as SDPP level increased. Similarly, for litter for Y or M group sows. the Y sow group there was a significant quadratic reduc- Results of litter size parameters in the second partur- tion of percent stillborn pigs as SDPP level increased ition are presented in Table 5. The total born pigs in the and an indication (P = 0.12) of a parity and diet inter- next litter were analyzed with the covariance of total action like that for number of stillborn pigs. For the M born pigs in the first parturition. Total born pigs per lit- ter in the second parturition for the All sow group was Crenshaw et al. Porcine Health Management (2021) 7:11 Page 11 of 16 Table 8 Correlation coefficients of serology variables with litter number and percentage of stillborn and mummified pigs size variables in the second parturition. Parity or parity by diet interac- First parturition Second parturition tions were not significant for number or percentage of Stillborn a Total bornb stillborn or mummified pigs per litter in the second par- Variable r P= n Variable r P= n turition for any sow group, except for a tendency (P = Total borna 0.4874 0.0003 50 Total borna −0.0078 0.9584 47 0.09) for a parity effect on percentage stillborn pigs in the M group of sows. However, number of stillborn pigs IFN-αa −0.1202 0.5503 27 IFN-αb 0.0236 0.9033 29 increased quadratically with SDPP level for all sows and IFN-γ −0.2280 0.2528 27 IFN-γ −0.2736 0.1436 30 the Y sow group. There were no parity or parity and diet IL-10 0.1724 0.3898 27 IL-10 0.1549 0.4136 30 interaction for the number or percentage of mummified IL-1β −0.1251 0.5340 27 IL-1β 0.0447 0.8144 30 pigs for any of the sow groups. In the Y sow group there IL-4 −0.0488 0.8090 27 IL-4 0.1746 0.3561 30 was a significant linear increase in number and percent- IL-6 0.0919 0.6486 27 IL-6 0.0207 0.9135 30 age of mummified pigs with increased SDPP level in the peripartum diet. IL-8 −0.0488 0.8395 27 IL-8 0.1175 0.5363 30 The change in total and live born pigs per litter from TNF-α 0.4123 0.0326 27 TNF-α 0.0318 0.8675 30 the previous to the next parturition was calculated con- IL-12 −0.0764 0.7050 27 IL-12 0.0719 0.7059 30 sidering that litter size for total born in the previous par- MDA −0.0276 0.8770 34 MDA −0.0539 0.7734 31 turition was already established before the peripartum SOD −0.0154 0.9311 34 SOD 0.0451 0.8062 32 diet was fed, but that subsequent litter size could poten- TAS 0.1148 0.5249 33 TAS 0.0125 0.9498 28 tially be impacted by feeding SDPP in the peripartum diet. The change in total born pigs per litter for all sows GPx 0.1769 0.3169 34 GPx −0.3581 0.0347 35 was significant for parity and the interaction of parity Values are Pearson correlation (r) coefficients, T-test probability (P =) and number (n) of observations per variable and diet and presented a linear increase (P < 0.05) with a Total born or stillborn results of first parturition were correlated with increasing SDPP level in the peripartum diet. Change in serology variables of sows sampled 2 days prepartum total born for the Y sow group was linearly increased b Total born results of second parturition were correlated with serology variables of sows sampled 4 days postpartum (P < 0.01) with increased SDPP level fed during the first parturition. Within the Y group of sows, the linear pat- significantly affected by parity and there was a significant tern of increased change in total born was similar for parity by diet interaction. Total born pigs in the next lit- parity 1 and parity 2 sows and there was no significant ter was increased linearly (P = 0.02) for Y sows fed in- parity and diet interaction. There were no significant creased SDPP levels in the peripartum diet that was only diet effects on change of total born for the M sow group, fed during the first parturition, but there was no signifi- but the effect of parity differed. cant parity and diet interaction. Both parity 1 and parity Change in live born litter size was significantly affected 2 sows presented a similar linear increase in total born by parity for all sows and the M sow group and there pigs as SDPP level increased in the diet. Sow age at the was a parity by diet interaction for all sows. For the Y second parturition was also evaluated as a covariant in sow group there was a linear increase (P < 0.01) in the model for the Y sow group. Average sow age at the change of live born pigs as SDPP level increased in the next parturition for parity 1 sows was 73.9, 72.6 and diet, whereas there were no significant effects of diet in 72.4 weeks per respective increasing level of SDPP and the M sow group. Within the Y group there was no sig- for parity 2 was 93.4, 93.5 and 93.0 weeks. However, sow nificant diet and parity interaction. Both parity 1 and age did not have any significant influence on the effect parity 2 sows presented an increased linear pattern of of diet for total born pigs. Sow age at the second partur- change in live born pigs as SDPP level increased in the ition had a low correlation (r = 0.0914) with total born peripartum diet. litter size (Table 6). Total born pigs per litter in the sec- Pearson correlation coefficients and probability (T-test) ond parturition for the M sow group was significantly af- for variables related to litter size in the first and second fected by parity but was not significantly affected by diet. parturition are presented by sow group in Table 6. In the Live born pigs per litter in the second parturition for first parturition, the number of stillborn pigs had a signifi- all sows and M sow groups were significantly affected by cant and positive correlation with total born pigs and the parity, but not by diet. Live born pigs in the second par- correlation was higher for the M group (r = 0.4577) rela- turition for the Y sow group tended (P = 0.09) to present tive to the Y group (r = 0.2746). Sow age at the first par- a linear increase in litter size relative to increased SDPP turition had a low correlation (r = 0.0909) with total born level fed in the first parturition. in the Y sow group. The correlation of total born pigs in The covariance of total born litter size in the second the first parturition with total born in the second partur- parturition was used in the model to evaluate the ition was not significant and was slightly negative for each Crenshaw et al. Porcine Health Management (2021) 7:11 Page 12 of 16 sow group. In the second parturition, the number of still- Nutrition studies conducted at commercial farms can born was significant and positively correlated with total provide relevant data with large numbers of sows per born pigs, again with a higher coefficient for the M group diet, but results can sometimes be challenging to inter- (r = 0.2739) relative to the Y group (r = 0.1329). As in the pret. Appropriate statistical models that adjust for vari- first parturition, sow age at the second parturition for the ance associated with physiological, production, and Y group of sows had a low correlation (r = 0.0914) with management factors are needed to best interpret effects total born pigs in the second parturition. of dietary treatments. Parity of sow is an important fixed effect to evaluate in sow studies because physiological variables, such as sow body weight, pig weight at birth Serology results or at weaning, and total born litter size are known to dif- Serology results presented in Table 7 revealed no signifi- fer by parity of the sow, particularly for primiparous cant effect of diet on the various cytokines analyzed. sows compared to multiparous sows. When using a roll- Higher levels of IL-8 were detected (P < 0.05) during the ing allotment of diets to sows by parity over a 4-month postpartum period compared to the prepartum period. interval under a continuous farrowing schedule, it be- There was a linear increase (P < 0.01) for GPx as SDPP comes difficult to maintain a balanced allotment of diets in peripartum feed increased. The other oxidation status to sows by parity. The number of mature (parity 3 to 8) markers were not different among peripartum diets, but sows allotted across dietary treatments in the current sampling period differed (P < 0.05) for MDA and tended study was variable and collectively represented 35% of (P = 0.07) to differ for SOD, both of which were higher the sows used in the study (Table 1). However, the num- in the postpartum period (day 4 of lactation) compared ber of young (parity 1 and 2) sows which collectively to the prepartum period (2 days before expected partur- represented 65% of the sows used in the study, were ition at 115 days of gestation). There were no significant equally allotted by parity 1 or 2 sows within diet but interaction of diet and sampling period for cytokine or there were more young sows allotted to the 0.5% SDPP oxidation status markers. diet compared to the other diets. When using parity of Pearson correlation coefficients of prepartum serology sow in the statistical model, the calculated LSM and variables with stillborn pigs in the first parturition and SEM can become skewed especially with unequal distri- postpartum serology variables with total born pigs in the bution of sows allotted to diet by parity and the effects second parturition are presented in Table 8. The num- of dietary treatments may become less detectable. There- ber of stillborn pigs in the first parturition were signifi- fore, data from sows were grouped as Y (combined par- cantly and positively correlated (r = 0.4874) with total ity 1 and 2 sows) or M (parity 3 to 8 sows) and then born pigs and with serum TNF-α (r = 0.4123) samples analyzed as separate datasets to reduce the skewed ef- collected prepartum. In the second parturition there was fects on LSM and SEM when using the unequal distribu- a significant negative correlation (r = − 0.3581) between tion of parity by diet in the model analysis for all sows. total born pigs and results of GPx samples collected on The results for variables associated with feed intake of day 4 postpartum. the peripartum diets, backfat depth of sows, and post- weaning sow reproduction are presented in Table 3. By Discussion design, the peripartum diets were provided to sows at 3 Previous studies using 0.5% SDP in lactation feed have re- kg per day from entry in maternity (approximately day ported several production improvements including higher 109 of gestation) to the day of parturition, then sows ad libitum lactation feed intake by parity 1 and 2 sows, re- were provided 4.5 kg of the peripartum diet on day 1 to duced wean-to-first-estrus interval for parity 1 sows [20], 5 postpartum. Daily feed refusals of the peripartum diets increased subsequent farrowing rate [21], increased pre- were recorded and average daily feed intake of the peri- wean survival [19, 22, 23], increased litter weight, and in- partum diets were corrected for feed refusals. Feed re- creased average pig weight at weaning [20, 21] with more fusals by individual sows can be common, especially full-value pigs weaned per litter [20, 21]. However, data is around the time of parturition. Due to the variable days lacking to establish the optimum level and feeding dur- from entry to parturition, the covariance of total days ation of SDP in sow diets at strategic periods of the breed- the peripartum diets were fed was used in the model to ing herd lifecycle, especially when using current sow evaluate average daily peripartum feed intake for data- genetics that have been selected to produce larger litter sets including all sows and Y sows, but could not be size than those of the past decade. The current study is used to evaluate feed intake of sows in the M group be- the first known to evaluate the short-term feeding of vari- cause convergence criterion for this covariant was not able levels of SDPP in peripartum feed for sows when pro- met and LSM for diet could not be calculated. Average vided from entry in maternity (109 days of gestation) daily peripartum feed intake corrected for feed refusals through day 5 postpartum. and adjusted by total peripartum feed days did not differ Crenshaw et al. Porcine Health Management (2021) 7:11 Page 13 of 16 for the effect of diet for all sows or the Y sow group. was available for parity 1 and 2 sows and was used as a Without using the covariance of total peripartum feed potential covariant in the model to explain the lower days in the M group of sows, the effect of peripartum total born litter size of the parity 1 and 2 sows allotted diet presented a significant quadratic response to SDPP to the 2.5% SDPP diet. Correlation of sow age and total level in the diet, however only 4 mature sows had any born was very low (Table 6) and the covariance of sow recorded feed refusals so the effect of diet was likely re- age did not change the effect of diet on total born. Sow lated to differences in total peripartum feed days. age of the Y sow group at the second parturition also After ceasing the feeding of the peripartum diets at had a very low correlation with total born of the second day 5 postpartum, sows were provided a common lacta- parturition and did not change the effect of diet on total tion feed ad libitum (3 feedings per day) to weaning and born in the second parturition when used in the model. a common gestation feed to the next parturition. Aver- In the Y group of sows there was a linear decrease in age sow backfat depth at entry and weaning was re- live born as SDPP level increased, but there was an indi- corded and results indicated no significant effects of cation (P = 0.12) of a quadratic effect of SDPP for live peripartum diet on backfat loss from entry in maternity born pigs from all sows during the first parturition. Ob- to weaning. Days from entry to weaning (average 30.42 viously, the difference in live born litter size relative to days) was used as a covariant in the model for evaluating total born is the sum of stillborn and mummified pigs. backfat depth at weaning and backfat depth loss, but this Stillborn pigs per litter was moderately correlated with covariant did not change the effects of diet on these vari- total born litter size in the first parturition, but more so ables. These results suggest that variations in feed re- in the M group (r = 0.4577) compared to the Y group fusals of the peripartum diets had limited impact on sow (r = 0.2746) of sows (Table 6). Using total born litter size backfat loss from entry to weaning. However, the role of as a covariant in the model, the number of stillborn pigs the common lactation feed consumption on backfat loss from all sows had a tendency (P = 0.06) for a diet effect is unknown because feed consumption of the common with a linear decline in stillborn as level of SDPP in- lactation diet was not recorded. In a previous publication creased. Although diet effects on stillborn pigs in the [20] the use of 0.25% SDP in lactation feed for 14 days first parturition were not significant for the Y or M for sows farrowed in summer months reduced (P = 0.06) group of sows, the numerical indication followed a simi- sow body weight loss of parity 1 and 2 sows and in- lar pattern as for all sows with less stillborn pigs per lit- creased (P < 0.01) lactation feed intake, whereas in win- ter for sows fed diets with SDPP. For stillborn pigs as a ter months there was a tendency (P = 0.09) for reduced percentage of total born pigs there was a significant sow body weight loss during a 14 d lactation period with downward quadratic (P = 0.04) response as level of SDPP no significant effect on sow feed intake when primipar- increased for all sows and the Y group of sows. Other ous and multiparous sows were fed 0.25% SDP in lacta- factors such as litter size, birth weight, sow weight, par- tion feed. ity, and assisted births can also impact stillbirths [12], Lactation feed intake of parity 1 and 2 sows during but in our study total born litter size as a covariant in summer months has also been shown to significantly in- the model did not change the significance of the diet crease with 0.5% SDP in sow diets fed during an 18 day effect. lactation with a reduced wean-to-first-estrus interval for The downward quadratic response to SDPP level for parity 1 sows [20]. However, diet effects on the wean-to- percentage of stillborn pigs could reflect a dietary re- first-estrus interval and wean-to-final-service interval for sponse because sows had consumed the peripartum diets sows fed the peripartum diets (Table 3) was not signifi- for an average of 6.1 days prepartum. Other studies have cantly different for all sows or the Y or M sow groups demonstrated reduced parturition time and stillbirths when analyzed with or without the covariance of the are associated with a higher energy status of the sow interval of days from entry in maternity to weaning [32] and use of fiber in sow diets [33]. However, still- (average 30.42 days). The effects of dietary SDP on births were not affected by increased feeding levels in wean-to-first-estrus interval may differ based on dietary late gestation [4], but gilts with lower feed intake had a level and duration of the lactation period, along with lower percentage of stillbirths than gilts fed higher feed seasonal effects on sow feed intake during lactation. intake in late gestation [5]. Stillbirths occur during par- The total born litter size at the first parturition (Table turition and are highly associated with a prolonged par- 4) was significantly lower for sows allotted to the 2.5% turition time [16]. In our study, parturition duration was SDPP diet. Although total born litter size had been not recorded, but future studies should be designed to established before sows were provided the peripartum understand if dietary SDPP affects duration of diets, the difference in total born by diet at allotment parturition. made it more difficult to interpret diet effects on other In the second parturition (Table 5) there was a signifi- litter size variables. Age of sow at the first parturition cant linear increase in total born litter size and a similar Crenshaw et al. Porcine Health Management (2021) 7:11 Page 14 of 16 tendency (P = 0.09) for a linear increase in live born litter subsequent litter size and potentially reduce the culling size for the Y group of sows that had been fed increasing rate of young parity sows due to low litter size. SDPP levels in peripartum feed during the first partur- The potential mechanisms of SDPP in peripartum di- ition. The covariance of total born litter size in the first ets that resulted in reduced stillborn pigs in the first par- parturition was used in the model for analysis of total turition and the longer-term increase in litter size in the born litter size in the second parturition because of the second parturition for young parity sows fed peripartum allotted diet differences for total born in the first partur- diets containing SDPP are not clearly understood. In ition. However, correlations of total born in the first par- other studies, during late pregnancy under LPS-induced turition with the second parturition total born litter size inflammation, mice fed diets with 8% SDP had reduced were very low within each sow group (Table 6) and did overstimulation of pro-inflammatory cytokines in uterine not significantly influence the diet effect of total born lit- mucosa and placenta and had lower lethargic reactions ter size in the second parturition. Within the Y sow to LPS [29]. Recently, sows and their weaned progeny group, the linear pattern of response to litter size and had lower serum TNF-α and cortisol when the sows change in litter size was consistent for both parity 1 and were fed 1% SDP in feed during the last trimester of ges- parity 2 sows. The change in litter size from the first tation and during lactation compared to control sows parturition to the second parturiton for the Y group of and their progeny [38, 39]. However, in the current sows resulted in approximately 1 and 2.45 more change in study there were no significant diet effects related to total born pigs per litter for the sows fed peripartum diets serum cytokine profiles of peripartum sows (Table 7) be- with 0.5 and 2.5% SDPP, respectively. In a past study [20] fore or after parturition. Postpartum dysgalactic syn- there was a numerical indication (P = 0.22) for about 0.9 drome sows have more pronounced and significant more live pigs born per litter for gilts in their next partur- changes in some hormone, metabolic and inflammatory ition when previously fed 0.5% SDP in lactation feed dur- serum markers than normal sows before and after par- ing their initial lactation, which averaged about 18 days. turition [14, 15]. The lack of detectable diet differences At the commercial farm for the current study, the average in our study for cytokine profiles may have been due to total born litter size during the previous year of the study variable stress status of the sampled sows near partur- reported a 0.4 pig increase from parity 1 to 2, a 0.2 pig in- ition or insufficient sample size. A post hoc power test crease from parity 2 to 3, and a 0.3 pig increase from par- for a significant F-test probability with a model of fixed ity 3 to 4, then the average total born declined as parity effects and interactions indicated 126 samples were increased beyond parity 4. During the previous year before needed to detect a 0.4 difference of the fixed effects. In the current study was initiated, the farm was transitioning Table 8 there was a significant moderate correlation (r = to a different genetic supplier so the production records of 0.4123) of prepartum TNF-α and number of stillborn in total born litter size changes by parity may not reflect dif- the first parturition suggesting a potential correlation of ferences observed in the current study which only used this inflammatory cytokine with increased stillborn pigs. sows from the current genetic supplier (Naima Choice When postpartum cytokines were correlated with total Genetics). Although it had been over 4 months since born in the second parturition, there were no significant SDPP had been fed in the current study, prior feeding of correlations but an indication (P = 0.1436) of an inverse SDPP during the initial 5 days postpartum of the previous correlation (− 0.2736) with IFN-γ. For oxidation status lactation could have potentially impacted postpartum markers, there was a linear increase in serum GPx as diet- uterus recovery and possibly affected ovarian function. ary SDPP level increased in both sampling periods sug- Small follicles (< 5 mm) are present in the ovaries of lac- gesting an improved antioxidant status of sows fed SDPP tating sows and they undergo atresia or recruitment for around parturition (Table 7). However correlation of pre- further development in later lactation prior to ovulation 4 partum GPx with number of stillborn in the first partur- to 7 days post-weaning [34]. ition was not significant and low (r = 0.1769), while Reproductive performance can vary by individual sow postpartum GPx had a significant and moderate inverse within the same farm, especially in hot climates [35]. correlation (r = − 0.3581) with total born litter size in the However, the number of pigs born alive per litter for par- second parturition. However, these correlations of sero- ity 1 and 2 sows has been considered a good predictor for logical markers with stillborn pigs and litter size include lifetime sow reproductive performance [36, 37]. Young only a subset of 50 or less sows used in the study. parity sows with low litter size are often culled, while those with higher litter size are kept in the herd. In our Conclusions study, the linear increase in total and live born litter size Strategic use of SDPP in peripartum sow feed may have of the next parturition for the young parity sows previ- merit for reducing stillborn pigs and have longer-term ously fed increased levels of SDPP during their initial par- beneficial effects on litter size in the next parturition for turition suggest that SDPP in peripartum feed can benefit parity 1 and parity 2 sows. Crenshaw et al. Porcine Health Management (2021) 7:11 Page 15 of 16 Abbreviations Received: 23 July 2020 Accepted: 27 November 2020 SDP: Spray-dried animal plasma; SDPP: Spray dried porcine plasma; SDBP: Spray-dried bovine plasma; GPx: Glutathione peroxidase; SOD: Superoxide dismutase; MDA: Malonaldehyde; TAS: Total antioxidant status; TNF-α: Tumor necrosis factor alpha; IFN-α: Interferon alpha; IFN- References γ: Interferon gamma; IL-1β: Interleukin 1β; IL-4: Interleukin 4; IL-6: Interleukin 1. Gonçalves MAD, Dritz SS, Tokach MD, Piva JH, DeRouchey JM, Woodworth 6; IL-8: Interleukin 8; IL-10: Interleukin 10; IL-12: Interleukin 12; SAS: Statistical JC, et al. Fact sheet – impact of increased feed intake during late gestation Analysis System; PROC MIXED: Mixed model procedure of SAS; PROC on reproductive performance of gilts and sows. J Swine Health Prod. 2016; CORR: Procedure of SAS for calculating Pearson correlation coefficients; 24(5):264–6. https://www.aasv.org/library/swineinfo/Content/SHAP/2016/v24 LSM: Least squares mean for peripartum diet; SEM: Pooled standard error of n5p264.pdf. Accessed 7 Jan 2021 the mean for peripartum diet; r: Pearson correlation coefficient; P: Probability 2. Che L, Hu L, Wu C, Xu Q, Zhou Q, Peng X, et al. Effects of increased energy of F-test or T-test; L: Linear contrast of peripartum diet containing 0, 0.5 or and amino acid intake in late gestation on reproductive performance, milk 2.5% SDPP; Q: Quadratic contrast of peripartum diet containing 0, 0.5 or 2.5% composition, metabolic, and redox status of sows. J Anim Sci. 2019;97:2914– SDPP; PR: Fixed effect of sow parity or designated sow parity; D: Fixed effect 26. https://doi.org/10.1093/jas/skz149. of peripartum diet; INT: Interaction of PR or SP and D; All: Dataset analyzed 3. Gonçalves MA, Gourley KM, Dritz SS, Tokach MD, Bello NM, DeRouchey JM, that included all parity sows; Y: Dataset analyzed using only young sows et al. Effects of amino acids and energy intake during late gestation of (combined data of parity 1 and parity 2 sows); P1: Parity 1 sows (intended as high-performing gilts and sows on litter and reproductive performance gilt having first litter); P2: Parity 2 sows; VTM: Vitamin and trace mineral under commercial conditions. J Anim Sci. 2016;94:1993–2003. https://doi. premix org/10.2527/jas.2015-0087. 4. Mallmann AL, Betiolo FB, Camilloti E, Mellagi APG, Ulguim RR, Wentz I, et al. Two different feeding levels during late gestation in gilts and sows under Acknowledgements commercial conditions: impact on piglet birth weight and female The authors thank the ownership of the commercial farm for housing reproductive performance. J Anim Sci. 2018;96:4209–19. https://doi.org/10. animals and providing production records. 1093/jas/sky297. 5. Mallmann AL, Camilotti E, Fagundes DP, Vier CE, Mellagi APG, Ulguim RR, et al. Impact of feed intake during late gestation on piglet birth weight and Authors’ contributions reproductive performance: a dose-response study performed in gilts. J Anim Joe C, LS, ST, CR, Joy C and JP designed the study; Joe C, LS, Joy C, ST and Sci. 2019;97:1262–72. https://doi.org/10.1093/jas/skz017. JP developed the nutritional strategy provided in this study; LL and LS 6. Samuel RS, Moehn S, Pencharz PB, Ball RO. Dietary lysine requirement of conducted the experiment at the farm and collected the performance data sows increases in late gestation. J Anim Sci. 2012;90:4896–04. https://doi. and serum samples; DS and JG conducted the serum analysis; Joe C, CR, Joy org/10.2527/jas.2011-4583. C and JP provided statistical analysis and co-wrote the paper. All authors 7. Zhang S, Qiao M, Trottier NL. Feeding a reduced protein diet with a near contributed to revisions and read and approved the final manuscript. ideal amino acid profile improves amino acid efficiency and nitrogen utilization for milk production in sows. J Anim Sci. 2019;97:3882–97. https:// doi.org/10.1093/jas/skz220. Funding 8. Quesnel H, Meunier-Salaün MC, Hamard A, Guillemet R, Etienne M, Farmer Funds were provided by APC-Europe, S.L.U. Granollers, Spain for support LL C, et al. Dietary fiber for pregnant sows: influence on sow physiology and and LS who conducted the study and collected data and for serology performance during lactation. J Anim Sci. 2009;87:532–43. https://doi.org/10. analyses expenses by DS and JG. 2527/jas.2008-1231. 9. Loisel F, Farmer C, Ramaekers P, Quesnel H. Effects of high fiber intake Availability of data and materials during late pregnancy on sow physiology, colostrum production, and piglet The data that supports the findings of this study are available from the performance. J Anim Sci. 2013;91:5269–79. https://doi.org/10.2527/jas.2013- corresponding author upon reasonable request. 6526. 10. Jensen MB, Pedersen LJ, Theil PK, Yde CC, Bach-Knudsen KE. Feeding motivation and plasma metabolites in pregnant sows fed diets rich in Ethics approval and consent to participate dietary fiber either once or twice daily. J Anim Sci. 2012;90:1910–9. https:// Animal Care Statement: The experiment was done at a commercial sow farm doi.org/10.2527/jas.2010-3289. that fulfilled animal housing standards and management by farm animal 11. Shang Q, Liu H, Liu S, He T, Piao X. Effects of dietary fiber sources during caretakers, trained to abide by authoritative animal welfare standards late gestation and lactation on sow performance, milk quality, and intestinal established by the Law on Animal Welfare 2/2008 published by Diari Oficial health in piglets. J Anim Sci. 2019:4922–33. https://doi.org/10.1093/jas/ de la Generalitat Catalunya. skz278. 12. Le Cozler YL, Guyomarc’h C, Pichodo X, Quinio PY, Pellois H. Factors associated with stillborn and mummified piglets in high-prolific sows. Anim Consent for publication Res. 2002;51:261–8. https://doi.org/10.1051/animres:2002017. Not Applicable. 13. Farmer C. Nutritional impact on mammary development in pigs: a review. J Anim Sci. 2018;96:3748–56. https://doi.org/10.1093/jas/sky243. 14. Kaiser M, Jacobsen S, Andersen PH, Bækbo P, Cerón JJ, Dahl J, et al. Competing interests Hormonal and metabolic indicators before and after farrowing in sows Javier P, Joy C and Joe C are salaried employees of APC LLC, Ankeny, IA USA affected with postpartum dysgalactia syndrome. BMC Vet Res. 2018;14:334. and Carmen R and Javier P are employed by APC-Europe S.L.U, Granollers, https://doi.org/10.1186/s12917-018-1649-z. Spain. Both companies manufacture and sell spray dried blood products for 15. Kaiser M, Jacobson M, Andersen PH, Bækbo P, Cerón JJ, Dahl J, et al. use in animal feed. 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