Veterinary World, EISSN: 2231-0916 RESEARCH ARTICLE Available at www.veterinaryworld.org/Vol.13/July-2020/1.pdf Open Access Effect of soybean expeller supplementation during the final phase of sow gestation on litter birth weight Santiago Masi Mignaco1, Ana Alba-Casals2,3, Alicia Carranza1 and Julián Parada1,4 1. Departamento de Patología Animal, Facultad de Agronomía y Veterinaria, Universidad Nacional de Río Cuarto, Río Cuarto, Argentina; 2. IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, Barcelona, Spain; 3. The OIE Collaborating Centre for the Research and Control of Emerging and Re-emerging Diseases in Europe (IRTA-CReSA), Barcelona, Spain; 4. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina. Corresponding author: Julián Parada, e-mail: jparada@ayv.unrc.edu.ar Co-authors: SMM: santimasi@hotmail.com; AA: ana.alba@irta.cat; AC: acarranza@ayv.unrc.edu.ar Received: 22-11-2019, Accepted: 11-05-2020, Published online: 02-07-2020 doi: www.doi.org/10.14202/vetworld.2020.1245-1250 How to cite this article: Masi Mignaco S, Alba-Casals A, Carranza A, Parada J (2020) Effect of soybean expeller supplementation during the final phase of sow gestation on litter birth weight, Veterinary World, 13(7): 1245-1250. Abstract Aim: Nutrition plays a key role in the production of pigs, especially in pregnant sows, where modifications in nutritional requirements can affect their productive performance. The aim of this study was to evaluate nutritional supplementation with soybean expeller in sows during the last third of the gestation period and its effect on litter birth weight. Materials and Methods: A quasi-experimental study was conducted on a farrow-to-finish farm, where 192 sows were equally assigned to treatment and control groups. Several variables were recorded at both the sow and piglet level. The treatment group consisted of piglets from 95 sows supplemented with soybean expeller during the final phase of gestation (20 days), and the comparison group consisted of piglets from 97 sows fed only with a commercial balanced ration (control group). Results: Soybean expeller supplementation increased individual piglet weight by 190-270 g, and the increased number of live piglets could decrease the weight of each piglet. Moreover, the number of piglets weighing <900 g decreased by 10% as compared to the control group, indicating that supplementation could improve pre-weaning mortality. Conclusion: Our results suggest that soybean expeller supplementation in sows during the last third of the gestation period could improve production performance, especially on organic farms. Keywords: organic farms, piglet weight, production performance, sow nutrition. Introduction relationship between increased feed supply during this Nutrition plays a key role in the production of all period and improved embryo viability and even peri- animal species. The nutritional management of preg- partum variables [6]. However, this theory remains nant sows on traditional and organic farms is usually controversial. Other studies debate its usefulness limited to supplying the same feed throughout the and have even demonstrated an opposite effect [7,8]. whole period of gestation and adjusting the amount These differences in results can be explained by the provided based on the week of pregnancy. However, variability of factors such as sow parity, gestation this method does not take into account that the expo- time, and food nutrients and their effect on muscular nential growth of piglets during the last third of gesta- and nervous tissue growth in piglets [9]. The impor- tion modifies the nutritional requirements of sows [1]. tance of piglet weight at birth and its effect on mortal- An important relationship between nutrition at this ity and performance during fattening has been broadly stage and litter performance at farrowing has been demonstrated by several authors [10,11]. proposed by several researchers [2,3], even account- A wide variety of nutrients and food compo- ing for variation due to the number of parities (NP) nents have been proposed as limiting factors for piglet of the sow [4]. However, in some studies [5], varia- development and female productivity during the final tions in feed intake during gestation were more bene- phase of gestation [1]. Among these, levels of essential ficial for sows than for piglets. With regard to the last amino acids [12,13] and energy [14] have been most third of gestation, a previous study demonstrates the frequently studied. However, micronutrient-specific supplementation is often difficult to apply and is not Copyright: Masi Mignaco, et al. Open Access. This article is permitted on organic farms; thus, an alternative feed distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/ strategy, such as the use of soybean expeller, could by/4.0/), which permits unrestricted use, distribution, and improve productive performance in these situations. reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the The aim of this study was to evaluate nutritional Creative Commons license, and indicate if changes were made. supplementation with soybean expeller in sows during The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data the last third of the gestation period and its effect on made available in this article, unless otherwise stated. litter birth weight. Veterinary World, EISSN: 2231-0916 1245 Available at www.veterinaryworld.org/Vol.13/July-2020/1.pdf Materials and Methods Table-1: Daily nutritional intake for each sow from the 90th day of gestation either from the control group (base diet) Ethical approval or the soybean expeller supplemented group (treatment). The study was carried out in accordance with the guidelines laid down by the Research Ethics Feed Composition Base diet Treatment Committee of the National University of Río Cuarto. Protein (g) 404 546 Metabolizable energy (kcal) 8859 10,196 Study design, location and period Digestible lysine (g) 16.8 25.6 To evaluate the effect of the nutritional supplement Digestible arginine 22.4 33.8 on the performance of the piglets, a ­quasi-experimental Calcium 24.1 24.9 study was conducted on a commercial farm located in Phosphorus available 11.2 12.0 Córdoba with 220 sows between May and September of 2016. This site is a fully confined farrow-to-finish were collected: Individual identification of the sow, farm with a known history of good production perfor- type of nutritional treatment (NT) administered, NP, mance and health status. litter weight on average, and number of live-born and Data collection stillborn piglets within the litter. At the piglet level, We recorded data on litter performance from two the variables collected were individual identification different groups of sows over 20 consecutive weeks. of the piglet, type of NT administered to the mother, The treatment group consisted of piglets from 95 individual weight of the piglet at birth, number of pig- sows supplemented with soybean expeller during the lets born alive (BA) and stillborn within the same lit- final phase of gestation (20 days), and the compari- ter, and NP in which the piglet was born. son group consisted of piglets coming from 97 sows Statistical analysis fed only with a commercial balanced ration (control The process of analysis was comprised of differ- group). To control for confounding extraneous fac- ent steps. Initially, to detect and correct possible errors tors, each weekly breeding group was assigned to the in the raw data, the data were pre-processed. Then, control or treatment group. an exploratory descriptive analysis was carried out All females belonged to the same genetic line to summarize the main traits of each variable, assess and were considered for this study at the 90th day of gestation. The sows were housed in a barn with natu- their distribution, formulate hypotheses, identify ral ventilation in individual stalls (2 m × 0.6 m). The potential confounders, and design appropriate models feeding system was fully automated with individual to assess the influence of the soybean expeller supple- stall regulators. All sows were fed twice a day with a ment administered to the sows on the piglet perfor- gestation-balanced ration. Beginning on the 90th day mance at the litter and piglet level. With this goal, the of gestation, the amount of feed offered in both groups normality of each variable was assessed visually and was increased to 2.8 kg/day, and in the treatment tested using a Shapiro-Wilk test. Finally, to quantify group, 400 g of extruded and pressed soybean expeller the influence of the NT in sows on the performance (of known nutritional composition) was added once a of the piglets, parametric and non-parametric bivari- day with the morning feeding. ate analyses were conducted according to the distri- The feed was produced on the farm and was bution of each variable, and two explicative models stored in a silo outside the gestation barn. Maize was were proposed. First, the influence of feeding this produced on the farm and was analyzed for nutritional supplementary diet was analyzed by average weight control, as well as for mycotoxin levels, which were at the litter level. Here, a multiple linear regression acceptably low. was used, taking into account the initial explanatory During the study period, the soybean expeller variables “the group of nutritional treatment,” “the came from the same supplier. Its nutritional composi- number of parities,” and “the number of piglets born tion was analyzed by wet chemistry and n­ ear-infrared alive,” along with their possible interactions. The spectroscopy, which allowed us to determine the variables included in the final model were selected nutritional composition of the base diet and the soy- based on a manual stepwise procedure using the low- bean expeller supplemented diet (Table-1). est Akaike Information Criteria (AIC). To validate the At farrowing, live-born and stillborn piglets were model, a diagnostic checking of its residuals was con- counted to determine the total number of animals per ducted to guarantee heteroscedasticity and normality litter. In the calculation of the number of stillborn pig- and to identify possible influential observations. lets, the number of live-born animals that died shortly Next, the influence of the NT was assessed based after birth was not considered. Each piglet was weighed on the weight of each individual piglet using a mixed using a calibrated electronic scale with a maximum of linear model. This model included NT, NP, and BA 15 kg and an error of 0.005 kg after being attended by as fixed factors, with possible interactions between a midwife. Adequate measures were taken to minimize these factors and “the mother sow” as a random effect. pain or discomfort during the procedure. The variables included in the final model were also Diverse variables were recorded at the sow and selected based on a manual stepwise procedure using piglet level. At the sow level, the following variables the lowest AIC. Veterinary World, EISSN: 2231-0916 1246 Available at www.veterinaryworld.org/Vol.13/July-2020/1.pdf All statistical analyses and visual methods were performed using the base R program (R Development Core Team, 2015) and the lattice [15], ggplot2 [16], and lme4 [17] complementary packages. Results During the study, 192 farrowing sows were ana- lyzed: 97 in the control group and 95 in the treatment group. A total of 2142 live-born piglets were analyzed during the study: 1039 in the control group and 1103 in the treatment group. The number of piglets BA fol- lowed a normal distribution in both groups (Figure-1), Figure-1: Distribution of live-born piglets according to the with a mean of 10.7 piglets (SD 3.3) in the control group of nutritional treatment. group and 11.6 (SD 3.5) in the treatment group. However, the difference between the two groups was not statistically significant (Welch two-sample t-test with t=−1.79 and p=0.075). Seventy-two stillborn piglets were recovered from the 97 farrowing sows in the control group, representing an average of 5.75% of the litter, and a median of 0 (interquartile range [IQR] 1) piglet. In the treatment group, 94 stillborn piglets were recorded from the 95 farrowing sows, for an average of 7.35% of the litter and a median of 1 (IQR 1) stillborn piglet. Figure-2: Density plot of the average litter weight from treated and untreated (control) sows. The distribution of this variable was not normal, and the differences between the medians were slightly sig- nificant using a Mann–Whitney U-test, non-paramet- Weight pigletij = Intercept + βtNTj + βpNP*BAj ric test (p=0.042). + 1 | Sowi +ϵij The “individual piglet weight” did not follow a Here, the results showed that the soybean expel- normal distribution. In the control group, the median ler supplementation increased the individual piglet was 1.2 kg, with a minimum of 0.75 kg and a maxi- weight by 0.19-0.27 kg and that the higher number of mum of 2 kg. In the piglets from the treatment group, live piglets could decrease the weight of each piglet. the median was 1.4 kg, the minimum 0.8 kg, and the In addition, the results show that weight of each piglet maximum 2.5 kg. Using a Mann–Whitney U-test, was significantly influenced by the effect of each sow. statistically significant differences were observed Discussion between piglets from sows fed with or without soy- bean expeller supplementation (p<0.01). Similar Soybean expeller supplementation in sows results were obtained by comparing the average litter during the last third of gestation increased the weight weight (Figure-2). of live piglets from treated sows by more than 200 g The final model proposed included the NT and as compared to the control group. According to a pre- the interaction between BA and NP as explanatory vious study [1], this difference could be due to the variables (Table-2) and could be expressed as follows: increase in the supply of essential amino acids such Average weight litterj = Intercept + βtNTj + as arginine in the diet. Other possible explanations in βtpBA: NPj + ϵj, the literature point to lysine as being responsible for with ϵj being the model error for the subject j, this improvement in weight since it is a strictly essen- where ϵj ~ N(0,σ2). tial amino acid not synthesized by pigs [12] and is of The confidence intervals of this model indicated great importance for the development of both primary that the soybean expeller supplementation in sows was and secondary muscle fibers [7,18]. This was demon- associated with an increase in average weight between strated by a previous study [19], which reported that 180 and 270 g. In addition, the number of piglets BA under a diet with high inclusion of lysine, sows pre- had a slight influence on the average weight of the lit- sented higher piglet at weaning and better nutritional ter. Figure-3 shows the diagnostic plots of the residual composition of colostrum and milk, especially with checks. No statistical differences were observed in the regard to the amount of fat and protein. weight of live-born piglets among the different parity Although this study did not use synthetic argi- numbers of sows from the studied groups (Figure-4). nine or lysine but opted for cheaper and easier to apply To assess the effect of the soybean expeller sup- supplementation, which makes it difficult to compare plementation in sows on the weight of each individual with the results obtained by the cited authors, know- piglet (Table-2), the final mixed linear model was as ing the nutritional composition of the soybean expel- follows: ler used can provide a framework for comparison. The Veterinary World, EISSN: 2231-0916 1247 Available at www.veterinaryworld.org/Vol.13/July-2020/1.pdf Table-2: Results of the linear model for average weight litter and weight piglet, in relation with NT, NP, number of BA piglets, and the interaction between BA and NP. Average weight litterj = Intercept + βtNTj + βtpBA : NPj + ϵj Variable β S.E. β 95% CI p Intercept 1.501 0.093 NT 0.227 0.023 0.182/0.273 <0.001 NP 0.041 0.020 −0.0003/0.082 0.051 BA −0.027 0.008 −0.044/−0.011 0.001 NP:BA −0.002 0.001 −0.006/−0.001 0.145 Weight pigletij = Intercept + βtNTj + βpNP*BAj+ 1 | Sowi +ϵij Variables Variance Std. Dev Random effects Sow 0.021 0.145 Variable Variance Std. deviation 95% CI Fixed effects Intercept 1.712 0.095 1.513/1.911 NT. control −0.228 0.022 −0.267/−0.186 NP 0.044 0.021 −0.0004/0.008 BA −0.026 0.008 −0.044/-0.008 NP:BA −0.003 0.001 −0.006/0.0008 NT=Nutritional treatment, NP=Number of parity, BA=Born alive, CI=Confidence interval Figure-3: Diagnostic plots of the residuals checks of l-model for weight of live-born piglets. 400 g of supplement contributed 0.40% more arginine an increase in the amount of gestation balanced ration and 0.31% more lysine to the daily intake as compared in the last third of gestation was more beneficial for to the control group diet, which could explain the the sow than for the piglets since differences were not increases in the performance of piglets from treated observed in the weight of the litter in sows fed more sows in light of the previous studies. than 3 kg compared to sows fed <3 kg. This suggests An increase in piglet weight has also been associ- that an increase in the amount of ration is not suffi- ated with the use of high-energy diets [14], where the cient per se to impact the piglets, but that a change in increase was slightly over 1000 Kcal/day in the sup- the composition of the formula is necessary. plemented sows. However, in other studies [20], the It is important to note that piglets with a birth energy increase in the diet did not necessarily affect weight of less than 900 g have 60% lower rate of sur- the weight of piglets, but did affect the body condi- vival compared to heavier piglets [2]. In the present tion of the sow. According to one previous study [5], study, the percentage of piglets below that weight was Veterinary World, EISSN: 2231-0916 1248 Available at www.veterinaryworld.org/Vol.13/July-2020/1.pdf Figure-4: Average weight of live-born piglets according to number of parity of the sow in treated (T) and control (C) groups. lower in the treatment group (4%) than in the control increase was related to the treatment and the number group (13%). Therefore, although they were not mea- of live piglets in the litter. Our results suggest that sured in the present study, it could be inferred that soybean expeller supplementation in sows might help under these conditions, pre-weaning mortality and to improve production performance, especially on possibly the number of weaned piglets per sow per organic farms. year would improve. This is supported by other stud- Authors’ Contributions ies [21] showing that weight is a determining factor in the survival of piglets at farrowing because it influ- SMM, AC, and JP designed the experiment. ences the vitality of the piglets as well as the ther- SM collected data and performed the experiment. moregulation capacity and growth of the newborns. AA and JP made the statistical analysis. All authors In addition, low birth weight reduces the mobility of were involved in the writing, analysis of the data, and the piglet due to lack of maturation of the nervous tis- reviewed the manuscript, and they approved the final sue, thus compromising suckling and increasing the manuscript. odds of crushing [9]. Moreover, it might improve the Acknowledgments growth performance of the herd because the higher the birth weight, the greater the daily weight gain of This study was financially supported by resources these animals at maternity as well as post-weaning from the Grupo Salud Porcina (GSP), National and during fattening [10]. University of Río Cuarto (CNPP.2018), Argentina. On the other hand, in the present study, the mag- Competing Interests nitude of the weight increases of the piglets at birth The authors declare that they have no competing decreased with each unit of increase in the number of interests. piglets per litter, a result that was supported by the previous studies [10,11,22]. In addition, although the Publisher’s Note treatment increased the average weight of the pig- Veterinary World remains neutral with regard lets, the within-litter birth weight variation was also to jurisdictional claims in published institutional greater. 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Amino Acids, 42(6): of amino acid nutrition on pregnancy outcome in pigs: 2111-2119. ******** Veterinary World, EISSN: 2231-0916 1250