Science of the Total Environment 665 (2019) 18–22 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Short Communication Effects of boom and bust grazing management on vegetation and health of beef cattle used for wildfire prevention in a Mediterranean forest Miguel Teruel-Coll a, Javier Pareja b, Jordi Bartolomé b, Emmanuel Serrano a, Gregorio Mentaberre a, Rafaela Cuenca a, Johan Espunyes a, Ferran Pauné e, Juan Antonio Calleja c,d,⁎ a Wildlife Ecology & Health Group (WE&H), Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Universidad Autónoma de Barcelona (UAB), Bellaterra, 08193 Barcelona, Spain b Ruminant Research Group, Universidad Autónoma de Barcelona (UAB), Bellaterra, 08193 Barcelona, Spain c Departamento de Biología Animal, Biología Vegetal y Ecología, Botánica, Universidad Autónoma de Barcelona (UAB), Bellaterra, 08193 Barcelona, Spain d CREAF, Cerdanyola del Vallès, 08193 Barcelona, Spain e Apartado de Correos 5, 08500 Vic, Spain H I G H L I G H T S G R A P H I C A L A B S T R A C T • The manipulative field study points toward new European Agro- environmental policies. • The “boom and bust grazing” manage- ment may affect Mediterranean vegeta- tion structure. • Cattle feed on flammable plant taxa. • Mediterranean forest fails to provide the energetic requirements of cattle. • The “boom and bust grazing” manage- ment needs further research. a r t i c l e i n f o a b s t r a c t Article history: Humans and wildfires have historically driven landscape structure in the Mediterranean basin. The Iberian Peninsula Received 29 December 2018 is not an exception to that rule, and therefore, farmers, researchers, and governments seek alternative tools to min- Received in revised form 2 February 2019 imize the loss of biodiversity and wildfire risks. Extensive livestock including beef cattle is currently promoted as a Accepted 2 February 2019 suitable management tool by European agro-environmental policies yet pieces of evidence exist regarding the recip- Available online 4 February 2019 rocal effects between cows and Mediterranean woody vegetation. In this work, we performed a field manipulation Editor: Paulo Pereira to evaluate whether free-ranging beef cattle without supplementary feeding, at high density (2 livestock units (LU)/ ha) for a short period of time i.e. “boom and bust grazing” management, are able to adapt their grazing preferences Keywords: to the Mediterranean woody vegetation without health impairment, and prevent from bush encroachment and Agro-environmental policies wildfires. For our purposes, a native herd of 14 adult cows was kept captive without supplementary feeding in a Diet 14 ha enclosure covered by Mediterranean vegetation for two months (April–June 2016). Plant and cattle fecal Encroachment and blood samples were collected to assess diet composition (plant cuticle microhistological analysis), fecal nitrogen Microhistology and protein contents of consumed plants, and the nutritional status (non-esterified fatty acids) of cattle. Our results Silvopastoral showed that cattle adapted their feeding habits toward a more woody diet including potentially flammable taxa but with some detrimental effects on health status. Hence, cattle cannot control woody vegetation for long periods of time without supplementary feeding. Further research should be oriented to explore other alternative approaches to minimize the health impairment of cattle used for control flammable vegetation in Mediterranean regions. © 2019 Published by Elsevier B.V. ⁎ Corresponding author at: Calleja, Universidad Autónoma de Barcelona (UAB), E-08193, Bellaterra, Barcelona, Spain. E-mail address: juan.calleja@gmail.com (J.A. Calleja). https://doi.org/10.1016/j.scitotenv.2019.02.037 0048-9697/© 2019 Published by Elsevier B.V. M. Teruel-Coll et al. / Science of the Total Environment 665 (2019) 18–22 19 1. Introduction around 600 kg.) was introduced in the fenced area at the beginning of April. Then, the herd was monitored from the 19th of April (mid-spring) In the late 1990s, there has been a growing interest for the use of to the 21st of June of 2016 (early summer). Animals were kept with free-ranging livestock for the management of vegetation structure to water supply but without supplementary feeding, and under high den- prevent bush encroachment and halt the loss of biodiversity and wild- sity: 2 livestock units (LU)/ha. Diet composition and quality including fire risk in the Mediterranean basin (Etienne et al., 1996). Although bromatological analyses of plants as well as nutritional and energy sta- cows are considered grass feeders (Hofmann, 1989), some research tus of cattle were studied by collecting plant, fecal and blood samples at has indicated its ability to feed on Mediterranean woody plants, in par- the onset (19th of April) and at the end of the experiment (21st of June). ticular at moderate to high densities (e.g. Henkin et al., 2005; The fecal samples from ten (out of 14) different individuals were Schoenbaum et al., 2017). The European agro-environmental policies taken and kept in sealed plastic bags and then frozen until analysis. have promoted the use of beef cattle to reconcile agricultural land use The diet composition was analyzed by microscopic identification of and wildfire prevention (Bernués et al., 2011). However, the toxicity 200–240 vegetal epidermic fragments per fecal sample, using the cuticle and poor quality of the edible phytomass of many Mediterranean microhistological analysis (Stewart, 1967). The total 4800 fragments woody plants, along with the low productivity of some Mediterranean were classified into four major groups: 1. Graminoids (Poaceae, grasslands, encourage farmers to use supplementary feeding and recur- Cyperaceae, Juncaceae, etc.), 2. Woody plants, 3. Forbs and 4. rent technological intervention (Brosh et al., 2006; Bartolomé et al., Bryophytes. 2011). Previous studies appointed that these management practices Diet quality and nutritional status of different cows (n = 10) were minimize the ability of cattle to control woody vegetation in Mediterra- assessed by fecal nitrogen (FN) (Villamuelas et al., 2017). The percent- nean landscapes (Provenza et al., 2003; Schoenbaum et al., 2017). age of FN was estimated using Near-Infrared Reflection Spectroscopy Some authors (e.g. Provenza et al., 2003) have suggested the use of (Lyons and Stuth, 1992) implemented in NIRSystem 5000® by Foss Elec- short-duration grazing at high stock densities, called “boom and bust tric A/S. Fecal samples were air-dried at 65 °C, milled to 0.5 mm, and grazing”, with limited or no use of supplementary feeding to force cattle scanned from 1100 to 2500 nm. Reflectance was recorded at 2-nm in- to feed on a broad array of plants including more woody plants. How- tervals and the fecal nitrogen percentage was predicted from the resul- ever, we currently lack empirical comprehensive data on the impact of tant reflectance pattern. The energy status (i.e., energy status = energy browsing in Mediterranean scrublands on diet quality and health status intake − energy requirement) of the same ten individuals was assessed of these large ruminants (Casasús et al., 2005), and hence support for by nonesterified fatty acids (NEFA) (Rudik et al., 2004) that has largely the current European agro-environmental policies. We, therefore, em- been used for monitoring the energetic status of cows (Adewuyi et al., pirically study by using a multidisciplinary approach, some specific 2005). Blood samples were collected into Vacutainer tubes with short-term effects of the “boom and bust grazing” management on cat- C2K2O4 and NaF as a glycolytic inhibitor. At the lab, samples were centri- tle health and consumption of Mediterranean woody vegetation. We fuged (915 ×g) for 5 min immediately after collection; plasma was aim to provide relevant insights to evaluate the environmental utility decanted and stored at −20 °C until analysis. NEFA assessment was per- of this management and eventually help to design more efficient mon- formed by a WAKO NEFA C Kit (Wako Chemicals GmbH, Germany). itoring protocols and agro-environmental policies focused on halt bush Bromatological analyses were performed to determine the quality of encroachment and wildfire risk in Mediterranean forested areas. seven browsed and grazed taxa: four shrubs (Erica multiflora, Rhamnus In this work, we took advantage of a field manipulative experiment alaternus L., Rosmarinus officinalis, Rubus ulmifolius Schott) and three to study the short-term effects of the “boom and bust grazing” manage- graminoids (Brachypodium retusum, B. phoenicoides, and Carex sp.). All ment in a beef cattle herd fenced in a Mediterranean woody environ- these taxa were selected on the basis of previous studies (e.g. ment. We specifically evaluated: (I) the ability of beef cattle to adapt Bartolomé et al., 2011) and direct observations. Ten samples (200 g in their typical grasser behaviour to a more woody vegetation in a Medi- total) from different sites and individuals within the fenced area were terranean forest at a high livestock rate and without supplementary collected and mixed for each plant taxa and date (April and June). feeding for two months; (II) the impact of the new feeding habits on Then, three subsamples of each plant taxa and date were used to obtain diet quality; and (III) the impact on the nutritional status of beef cattle. the percentage of the protein content following the procedures of Helrick (1990) and Van Soest et al. (1991). 2. Material and methods To explore whether cattle modified their feeding habits during the study period, we used Generalized Linear Mixed Models (GLMM) in- The study was conducted within the Montserrat range, in NE of cluding the proportion of plants consumed (assessed by fecal cuticle Spain (central point 41°40′09″N, 01°46′38″E) in 2016. The study area microhistological analysis), as response variable and plant type was fenced and consisted of 14 ha at 370–440 m a.s.l. with a mild topog- (i.e., graminoids, woods and forbs), sampling period (onset vs end) raphy (slopes b15%) integrated by small hills and valleys with multiple and their two-way interaction as fixed explanatory variables. To control aspects except East. Soils are poorly developed (haplic regosols), de- for individual effects, cow identification was included as a random inter- rived from calcareous conglomerates, sandstone, and marls (Icgc.cat, cept in our GLMM (Zuur et al., 2009). Model selection was based on the 2018; IUSS, 2015). The climate is typically Mediterranean with a long- Akaike information criterion (lowest AIC) and the Akaike differences term (1955–1999) average annual mean temperature of 13.3 °C, and (Δi) with respect to the best model. When the Δi wasb2 units, we ap- an annual rainfall of 610 mm distributed from autumn to spring, with plied the principle of parsimony to select the simplest model scattered summer storms (Ninyerola et al., 2000). The vegetation com- (Burnham and Anderson, 2002). We then estimated the Akaike weight prises 10 ha of a dense planted forest of Pinus halepensis Mill., with the (Wi), that is, the relative likelihood of the model given the data avail- understory saturated with Mediterranean woody plants (e.g. Erica able. Previous to any model interpretation, we checked for evidence multiflora L., Pistacia lentiscus L., Rosmarinus officinalis L.), and 4 ha of of overdispersion of residuals. Our response variable (plant frag- shrubby patches dominated by the same woody species growing in ments in %) were log transformed to achieve the GLMM assumptions the pinewoods. Among herbaceous plants, Poaceae species predomi- (Zuur and Leno, 2016). Pseudo R2 for our set of GLMM was estimated nate (Brachypodium retusum (Pers.) Beauv., and B. phoenicoides (L.) following Nakagawa and Schielzeth (2013). Finally, mean FN and Roem. et Schultes), plus underlying bryophytes carpets (Pleurochaete NEFA concentrations, as well as percentages of protein content squarrosa (Brid.) Lindb., Homalothecium sp.) on northern or shady from comparisons between the onset and the end of our experiment, slopes. were performed using Student's t-tests. However, due to the reduced A herd of 14 adult (N4 years old) cows of the native breed Bruna dels sample size for protein content, the t-test was based on 1000 Pirineus (130 cm tall to the withers and the top of the hips, and weighing bootstrapped replications. 20 M. Teruel-Coll et al. / Science of the Total Environment 665 (2019) 18–22 Table 2 1.5 Period Percentage of protein (mean ± standard deviation) obtained at the bromatological analy- Onset sis of three samples per taxa and date. Significant differences (p b 0.05, bootstrapped t-stu- dent test) in protein content between dates were observed in all plant taxa. End Taxa Woody/herbaceous Protein (%) 19th April 21st June Brachypodium phoenicoides Herbaceous 7.6 ± 1.01 5.0 ± 0.84 Brachypodium retusum Herbaceous 7.6 ± 0.46 5.1 ± 0.47 1.0 Carex sp. Herbaceous 10.3 ± 0.64 8.2 ± 47 Erica multiflora Woody 5.2 ± 0.56 5.1 ± 0.49 log(Plant consume) Rhamnus alaternus Woody 12.8 ± 0.63 11.5 ± 0.55 Rosmarinus officinalis Woody 9.7 ± 0.50 6.0 ± 53 Rubus ulmifolius Woody 15.7 ± 0.27 11.4 ± 0.35 Phillyrea angustifolia L., Pistacia lentiscus and Viburnum tinus L.) were 0.5 also consumed yet mainly at the end of the study period. The bromatological analysis by bootstrapped t-test showed a signif- icant (p b 0.01) decreasing tendency in the percentage of protein in every analyzed planta taxa but Erica multiflora (Table 2, Appendix B). Likewise, at the end of the field experiment, the FN of cows decreased by 1.6 times (t = −3.5, p-value = 0.006) confirming the consumption of less nutritious plants (Table 3). Along the same lines, NEFA concen- 0.0 trations in the herd increased two-fold (t = −3.5, p-value = 0.006) Graminoids Forbs Woody plants after two months without supplementary feeding (Table 3). Plant groups Fig. 1. Feeding habits of a herd of ten adult cows. Percentage of fragments summarised into 4. Discussion three informal groups. Bars and whiskers represent mean and standard deviation values, respectively. We confirm the prediction regarding the implementation of the “boom-bust grazing” management (Provenza et al., 2003). Cattle, with- GLMM were performed using the “lme4” package 1.1–17 version out supplementary feeding and under high density, increased the con- (Bates et al., 2015), pseudo R2 using “MuMIn” package 1.40.4 version sumption of sclerophyllous woody plants over two months while (Barton, 2018), and bootstrapping using the “boot” package 1.3–20 ver- fenced in a Mediterranean forest. As expected in grazing animals sion (Canty and Ripley, 2017) of the R software 3.5.1 version (R Core (Hofmann, 1989), cattle initially focused on herbaceous plants and Team, 2018). some shrubs with high protein content (e.g. Rhamnus alaternus and Rubus ulmifolius). Moreover, cattle also browsed a large series of 3. Results woody plants including taxa avoided in similar Mediterranean environ- ments under similar or even higher livestock rates but with supplemen- The model including the interaction between plant type and the pe- tary feeding (Bartolomé et al., 2011). In fact, after two months, cattle riod best explained the feeding habits of our herd of cows (Wi Period increased the consumption of several woody taxa (e.g. Erica multiflora, ∗ Plant type = 1, R2 = 25.8, Table 1 and Fig. 1). Plant type explained Olea europaea, Pistacia lentiscus) despite their low quality (Silanikove most (13.1%) of the observed variability in the feeding habits whereas et al., 1996 and references therein). Cattle only seemed to avoid the changes between sampling periods explained 3.5%. That indicates that dominant tree species (Pinus halepensis) probably due to the scarcity changes in the plant consume between periods significantly varied of saplings (i.e. young Pinus individuals with accessible branches), among all the plant types (p b 0.05). For example, cattle increased the which otherwise are consumed in other Mediterranean areas (Pfister consumption of woody plants and forbs (by 15.5 and 4.4% in the use re- et al., 2008). Cattle also consumed bryophytes, not by chance, given spectively) whereas the use of graminoid plants decreased (by 19%) that mosses grow close to the ground (b3 cm height) and possess deter- over time (Appendix A). Overall, cattle consumed a wide array of spe- rent chemical components that exert detrimental effects on nitrogen cies common to the understory layers including bryophytes (Appendix absorption (Ihl and Barboza, 2007 and references therein). This result A). In detail, the first target plants in spring were three graminoids, might reveal the lack of optimal resources or overgrazing (Ihl and Brachypodium phoenicoides, B. retusum, and Carex sp. Secondarily, two Barboza, 2007). Thus, without supplementary feeding, cattle might ef- woody plants, Rhamnus alaternus L. and Rubus ulmifolius, which doubled fectively modify forest structure by changing, in the short-term, the the percentage of protein of the graminoids (Table 2, Appendix A). Sev- density of different understory vegetation strata including woody and eral sclerophyllous shrubs (e.g. Erica multiflora, Olea europaea L., mossy vegetation. Table 1 Model selection for exploring changes in the feeding habits of ten different adult cows by analysing vegetal fragments grouped into three plant types (Woody plants, Forbs and Graminoids) from their respective 20 fecal samples collected in two periods: 10 in April and 10 in June. The Null model only included the intercepts as explanatory fixed variable. K = de- grees of freedom of the models, AIC = Akaike Information Criterion, Δi = difference of AIC respect to the best model, Wi = Akaike weight. The percentage of the observed feeding patterns variability explained by both the fixed and random terms (Conditional), by the fix (Marginal) and the random term are also provided. The best model is shown in bold. Biological model K AIC Δi Wi Conditional R2 Marginal R2 Random factor R2 Period ∗ plant type 8 262.01 0 1 25.8 16.7 9.1 Plant type 5 268.15 6.14 0.05 20.3 13.2 7.1 Period + plant type 6 269.13 7.12 0.03 20.7 13.4 7.3 Null model 3 304.08 42.07 b 0.01 – – – Period 4 305.71 43.71 b 0.01 0.2 0.1 0.1 M. Teruel-Coll et al. / Science of the Total Environment 665 (2019) 18–22 21 Table 3 Acknowledgments Mean ± standard deviation of ten fecal nitrogen (FN) and non-esterified fatty acid (NEFA) concentrations recorded in ten different adult cows at the onset (19th of April) and at the end of the experiment (21st of June). This project and manuscript were partially supported by Universidad Autonóma de Barcelona (UAB), Spanish Ministerio de Economia y Period FN (%) NEFA (mmol/L) Competitividad (MINECO) through a Ramon y Cajal agreement (RYC- Onset 2.76 ± 0.320 0.14 ± 0.03 2016-21120), Cienciactiva-CONCYTEC (concession contract number End 1.67 ± 0.31 0.28 ± 0.13 236-2015-FONDECYT), and the Life project “LIFE13 BIO/ES/000094”. Our thanks also to Andreu Colom, María Puig, Santiago Lavín, and “El Brunet” farm for their collaboration in laboratory and field works. In the spring (April), at the beginning of the study, all the studied plants, except Erica multiflora, showed higher protein values than References those needed for cattle maintenance, considering that the protein re- Adewuyi, A.A., Gruys, E., van Eerdenburg, F.J.C.M., 2005. Non esterified fatty acids (NEFA) quirement for cattle is around 14% for production and 7% for basal main- in dairy cattle. A review. Vet. 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