Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-15T13:26:09.511Z Has data issue: false hasContentIssue false
  • English
  • Français

Links between ruminants’ food preference and their welfare

Published online by Cambridge University Press:  10 March 2010

J. J. Villalba ,
F. D. Provenza  and
X. Manteca
J. J. Villalba*
Affiliation:
Department of Wildland Resources, Utah State University, 5230 Old Main Hill, Logan, UT 84322-5230, USA
F. D. Provenza
Affiliation:
Department of Wildland Resources, Utah State University, 5230 Old Main Hill, Logan, UT 84322-5230, USA
X. Manteca
Affiliation:
Unit of Animal Physiology, School of Veterinary Science, 08193 Bellaterra, Spain
*
†E-mail: [email protected]
Get access

Abstract

Nutrition is an important aspect of welfare, and in most recommendations for the welfare of animals adequate nutrition is a primary requirement. However, in intensive livestock production systems the decision for adequate nutrition is made based on traditional paradigms of feeding monotonous rations or plant monocultures, frequently with excesses or imbalances of nutrients relative to the individuals’ physiology, which can compromise welfare. Individual ruminants can better meet their needs for nutrients and regulate their intake of secondary compounds when offered a variety of foods than when constrained to a single food, even if the food is nutritionally balanced. The concept of food variety is central because monotonous flavors and feeds and excess nutrients all cause animals to satiate, which in turn causes animals to eat a variety of foods. When offered a variety of foods, satiety for single foods stimulates the selection of a diverse diet and thus food intake, but when restricted to a monotonous diet satiety is aversive and limits food intake. Moreover, if a monotonous diet is aversive to animals then this could be stressful, even if monotony implies consuming a balanced diet. A diverse diet may also increase resistance to disease in ruminants, by allowing consumption of small amounts of compounds with antimicrobial/antiparasitic effects and immunity-enhancing properties. Herbivores also experience the benefits of ingesting compounds with medicinal (i.e. antiparasitic) benefits and they learn to prefer foods containing such compounds as their preferences are associatively conditioned by the food’s homeostatic utility to the body. Such learned patterns of behavior begin in utero and feeding experiences early in life cause changes – neurological, morphological and physiological – in animals, which influence on their subsequent behavior and welfare. Such experiences with the environment enable animals to adapt to local diets and stressors and reduce the levels of fear. Finally, feeding behavior in farm animals could be an aid in the early detection and mitigation of pain or sickness, and as such become an important tool in the identification of welfare and health of animals before the appearance of clinical signs. Management strategies in ruminant production systems could benefit by allowing animals to manifest their feeding preferences, thereby acknowledging the animals’ role as active players in feeding systems, instead of regarding them as passive entities that just respond to prescriptions and formulations.

Keywords

foragingwell-beingfood selectionearly experiencenutrients
Type
Full Paper
Information
animal , Volume 4 , Issue 7: XIth International Symposium on Ruminant Physiology (ISRP), 6–9 September, 2009 Clermont-Ferrand (France) , July 2010 , pp. 1240 - 1247
Copyright
Copyright © The Animal Consortium 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Atwood, SB, Provenza, FD, Wiedmeier, RD, Banner, RE 2001a. Changes in preferences of gestating heifers fed untreated or ammoniated straw in different flavors. Journal of Animal Science 79, 3027–3033.Google Scholar
Atwood, SB, Provenza, FD, Wiedmeier, RD, Banner, RE 2001b. Influence of free-choice versus mixed-ration diets on food intake and performance of fattening calves. Journal of Animal Science 79, 3034–3040.Google Scholar
Balleine, BW, Dickinson, A 1998. The role of incentive learning in instrumental outcome revaluation by sensory-specific satiety. Learning & Behavior 26, 46–59.Google Scholar
Barry, TN, McNeill, DM, McNabb, WC 2001. Plant secondary compounds; their impact on nutritive value and upon animal production. Proc. XIX Int. Grass. Conf., SaoPaulo, Brazil. 19, 445–452.Google Scholar
Bechara, A, Tranel, D, Damasio, H, Adolph, R, Rockland, C, Damasio, AR 1995. Double dissociation of conditioning and declarative knowledge relative to the amygdale and hippocampus in humans. Science 269, 1115–1118.CrossRefGoogle Scholar
Berman, DG, Johnson, DE, Phillips, RW, Barry, BP 1980. Physiological and urinary metabolite responses to cold shock and confinement of sheep. Journal of Animal Science 50, 713–722.CrossRefGoogle ScholarPubMed
Berridge, KC, Robinson, TE 1998. What is the role of dopamine in reward: hedonic impact, reward learning, or incentive salience? Brain Research Reviews 28, 309–369.CrossRefGoogle ScholarPubMed
Bevans, DW, Beauchemin, KA, Schwartzkopf-Genswein, KS, McKinnon, JJ, McAllister, TA 2005. Effect of rapid or gradual grain adaptation on subacute acidosis and feed intake by feedlot cattle. Journal of Animal Science 83, 1116–1132.Google Scholar
Boissy, A 1998. Fear and fearfulness in determining behavior. In Genetics and the behavior of domestic animals (ed. T Grandin), pp. 67–111. Academic Press, San Diego, USA.Google Scholar
Boissy, A, Le Neindre, P 1997. Behavioral, cardiac and cortisol responses to brief peer separation and reunion in cattle. Physiology & Behaviour 61, 693–699.CrossRefGoogle ScholarPubMed
Broom, DM 1986. Indicators of poor welfare. The British Veterinary Journal 142, 524–526.Google Scholar
Burritt, EA, Provenza, FD 1997. Effect of an unfamiliar location on the consumption of novel and familiar foods by sheep. Applied Animal Behaviour Science 54, 317–325.Google Scholar
Carlstead, K, Shepherdson, D 2000. Alleviating stress in zoo animals with environmental enrichment. In The biology of animal stress. Basic principles and implications for animal welfare (ed. GP Moberg and JA Mench), pp. 337–354. CAB International, Wallingford.CrossRefGoogle Scholar
Chapple, RS, Lynch, JJ 1986. Behavioural factors modifying acceptance of supplementary foods by sheep. Research and Development in Agriculture 3, 113–123.Google Scholar
Coetzee, JF, Gehring, R, Bettenhausen, AC, Lubbers, BV, Toerber, SE, Thomson, DU, Kukanich, B, Apley, MD 2007. Attenuation of acute plasma cortisol response in calves following intravenous sodium salicylate administration prior to castration. Journal of Veterinary Pharmacology and Therapeutics 30, 305–313.CrossRefGoogle ScholarPubMed
Colpaert, FC, De Witte, P, Mondi, AN, Awouters, F, Niemegeers, CJE, Jansen, PAJ 1980. Self-administration of the analgesic suprofen in arthritic rats: evidence of mycobacterium butyricum-induced arthritis as an experimental model of chronic pain. Life Sciences 27, 921–928.CrossRefGoogle ScholarPubMed
Cooper, SD, Kyriazakis, I, Oldham, JD 1996. The effects of physical form of feed, carbohydrate source, and inclusion of sodium bicarbonate on the diet selections of sheep. Journal of Animal Science 74, 1240–1251.CrossRefGoogle ScholarPubMed
Cozier, A, Clifford, MN, Ashihara, H 2006. Plant secondary metabolites: occurrence, structure and role in the human diet. Blackwell Publishing, Oxford, UK.CrossRefGoogle Scholar
Critchley, HD, Rolls, ET 1996. Hunger and satiety modify the responses of olfactory and visual neurons in the primate orbitofrontal cortex. Journal of Neurophysiology 75, 1673–1686.Google Scholar
Danbury, TC, Weeks, CA, Chambers, JP, Waterman-Pearson, AE, Kestin, SC 2000. Self-selection of the analgesic drug carprofen by lame broiler chickens. The Veterinary Record 146, 307–311.Google Scholar
Dantzer, R, Arnone, M, Mormède, P 1980. Effects of frustration on behaviour and plasma corticosteroid levels in pigs. Physiology & Behavior 24, 1–4.CrossRefGoogle ScholarPubMed
Distel, RA, Villalba, JJ, Laborde, HE 1994. Effects of early experience on voluntary intake of low-quality roughage by sheep. Journal of Animal Science 72, 1191–1195.Google Scholar
Distel, RA, Villalba, JJ, Laborde, HE, Burgos, MA 1996. Persistence of the effects of early experience on consumption of low-quality roughage by sheep. Journal of Animal Science 74, 965–968.CrossRefGoogle ScholarPubMed
Dumont, B, D’hour, P, Petit, M 1995. The usefulness of grazing tests for studying the ability of sheep and cattle to exploit reproductive patches of pastures. Applied Animal Behaviour Science 45, 79–88.CrossRefGoogle Scholar
Dumont, B, Dutronc, A, Petit, M 1998. How readily will sheep walk for a preferred forage? Journal of Animal Science 76, 965–971.Google Scholar
Duncan, AJ, Elwert, C, Villalba, JJ, Yearsley, J, Pouloupoulou, I, Gordon, IJ 2007. How does pattern of feeding and rate of nutrient delivery influence conditioned food preferences? Oecologia 153, 617–624.Google Scholar
Early, D, Provenza, FD 1998. Food flavor and nutritional characteristics alter dynamics of food preference in lambs. Journal of Animal Science 76, 728–734.CrossRefGoogle ScholarPubMed
Engel, C 2002. Wild Health. Houghton Mifflin Co, Boston.Google Scholar
Ewing, SA, Lay, DC Jr, von Borell, E 1999. Farm animal well-being. Stress physiology, animal behavior and environmental design. Prentice Hall, New Jersey, NY, USA.Google Scholar
FAWC 1993. Second report on priorities for research and development in farm animal welfare. Farm animal welfare council. MAFF Tolworth, UK.Google Scholar
Fell, LR, Shutt, DA 1986. Use of salivary cortisol as an indicator of stress due to management practices in sheep and calves. Proceedings of the Australian Society of Animal Production 16, 203–206.Google Scholar
Fish, EW, Shahrokh, D, Bagot, R, Caldji, C, Bredy, T, Szyf, M, Meaney, MJ 2004. Epigenetic programming of stress responses through variations in maternal care. Annals of the NewYork Academy of Sciences 1036, 167–180.Google Scholar
Forbes, JM 2003. The multifactorial nature of food intake control. Journal of Animal Science 81, E139–E144.Google Scholar
Fraser, AF, Broom, DM 1997. Farm animal behaviour and welfare. CAB International, New York, NY, USA.Google Scholar
Freeland, W, Janzen, DH 1974. Strategies in herbivory by mammals: the role of plant secondary compounds. American Naturalist 108, 269–286.CrossRefGoogle Scholar
Gluckman, PD, Hanson, MA, Spencer, HG 2005. Predictive adaptive responses and human evolution. Trends in Ecology & Evolution 20, 527–533.CrossRefGoogle ScholarPubMed
Gordon, IJ, Illius, AW, Milne, JD 1996. Sources of variation in the foraging efficiency of grazing ruminants. Functional Ecology 10, 219–226.Google Scholar
Grade, JT, Tabuti, JRS, Van Damme, P, Arble, BL 2007. Deworming efficacy of Albizia anthelmintica in uganda: preliminary findings. African Journal of Ecology 45, 18–20.Google Scholar
Grade, JT, Tabuti, JRS, Van Damme, P 2009. Four footed pharmacists: indications of self-medicating livestock in karamoja, uganda. Economic Botany 63, 29–42.Google Scholar
Gregory, NG 2004. Physiology and behaviour of animal suffering. UFAW Animal Welfare Series. Blackwell Publishing, Oxford, UK.CrossRefGoogle Scholar
Hill, J, Chapman, DF, Cosgrove, GP, Parsons, AJ 2009. Do ruminants alter 1 their preference for pasture species in response to the synchronisation of delivery and release of nutrients? Rangeland Ecology & Management In Press.CrossRefGoogle Scholar
Hocquemiller, R, Cortes, D, Arango, GJ, Myint, SH, Cave, A, Angelo, A, Munoz, VFournet, A 1991. Isolation and synthesis of espintanol, a new antiparasitic monoterpenes. Journal of Natural Products 54, 445–452.CrossRefGoogle Scholar
Huber, TL 1976. Physiological effects of acidosis on feedlot cattle. Journal of Animal Science 43, 902–909.CrossRefGoogle ScholarPubMed
Huffman, MA 2003. Animal self-medication and ethno-medicine: exploration and exploitation of the medicinal properties of plants. Proceedings of the Nutrition Society 62, 371–381.CrossRefGoogle ScholarPubMed
Huffman, MA, Seifu, M 1989. Observations on the illness and consumption of a possibly medicinal plant Vernonia amygdalina by a wild chimpanzee in the Mahale Mountains National Park, Tanzania. Primates 30, 51–63.CrossRefGoogle Scholar
Huffman, MA, Ohigashi, H, Kawanaka, M, Page, JE, Kirby, GC, Gasquet, M, Murakami, A, Koshimizu, K 1998. African great ape self-medication: a new paradigm for treating parasite disease with natural medicines? In Towards natural medicine research in the 21st century (ed. H Ageta, N Aimi, Y Ebizuka, T Fujita and G Honda), pp. 113–123. Elsevier Science, Amsterdam, The Netherlands.Google Scholar
Jones, RB 1997. Fear and distress. In Animal welfare (ed. MC Appleby, BO Hughes), pp. 75–87. CAB International, Wallingford, UK.Google Scholar
Kayser, O, Kiderlen, AF, Croft, SL 2003. Natural products as antiparasitic drugs. Parasitology Research 90, S55–S62.CrossRefGoogle ScholarPubMed
Kilgour, RJ, Szantar-Coddington, MR 1997. The arena test and cortisol response of sheep as indirect selection criteria for the improvement of lamb survival. Animal Reproduction Science 46, 97–108.Google Scholar
Konarzewski, M, Diamond, J 1994. Peak sustained metabolic rate and its individual variation in cold-stressed mice. Physiological Zoology 67, 1186–1212.Google Scholar
Krachun, C, Rushen, J, de Passille, AM 2010. Play behaviour in dairy calves is reduced by weaning and by a low energy intake. Applied Animal Behaviour Science 122, 71–76.Google Scholar
Kyriazakis, I, Oldham, JD 1993. Diet selection in sheep: the ability of growing lambs to select a diet that meets their crude protein (nitrogen × 6.25) requirements. The British Journal of Nutrition 69, 617–629.CrossRefGoogle ScholarPubMed
Kyriazakis, I, Savory, J 1997. Hunger and thirst. In Animal welfare (ed. MC Appleby and BO Hughes), pp. 49–62. CAB International, Wallingford, UK.Google Scholar
Landgraf, R, Wigger, A, Holsboer, F, Neumann, D 1999. Hyper-reactive hypothalamo-pituitary-adrenocortical axis in rats bred for high-anxiety-related behaviour. Journal of Neuroendocrinology 11, 405–407.Google Scholar
Launchbaugh, KL, Provenza, FD, Werkmeister, MJ 1997. Overcoming food neophobia in domestic ruminants through addition of a familiar flavor and repeated exposure to novel foods. Applied Animal Behaviour Science 54, 327–334.CrossRefGoogle Scholar
LeDoux, J 2002. Synaptic self: how our brains become who we are. Viking Penguin, New York, NY, USA.Google Scholar
Lim, SS, Norman, RJ, Clifton, PM, Noakes, M 2009. Hyperandrogenemia, psychological distress, and food cravings in young women. Physiology & Behavior 98, 276–280.CrossRefGoogle ScholarPubMed
Lisonbee, LD, Villalba, JJ, Provenza, FD, Hall, JO 2009. Tannins and self-medication: implications for sustainable parasite control in herbivores. Behavioural Processes In Press.CrossRefGoogle ScholarPubMed
Lobley, GE, Milano, GD 1997. Regulation of hepatic nitrogen metabolism in ruminants. Proceedings of the Nutrition Society 57, 547–563.Google Scholar
Lozano, GA 1998. Parasitic stress and self-medication in wild animals. In Advances in the study of behavior (ed. AP Moler, M Milinski and PJB Slater), pp. 291–317. Elsevier Science, London, UK.Google Scholar
Manteca, X, Villalba, JJ, Atwood, SB, Dziba, L, Provenza, FD 2008. Is dietary choice important to animal welfare? Journal of Veterinary Behavior: Clinical Applications and Research 3, 229–239.Google Scholar
Matteri, RL, Carroll, JA, Dyer, CJ 2000. Neuroendocrine responses to stress. In The biology of animal stress: basic principles and implications for animal welfare (ed. GP Moberg and JA Mench), pp. 43–76. CAB International, Wallingford, CT, USA.Google Scholar
Meaney, M 2009. Epigenetic programming of behavior and physiology. Journal of Animal Science 87 (E-suppl. 2/J), 365.Google Scholar
Mellor, DJ, Stafford, KJ 2004. Animal welfare implications of neonatal mortality and morbidity in farm animals. Veterinary Journal 168, 118–133.CrossRefGoogle ScholarPubMed
Middleton, E Jr, Kandaswami, C, Theoharides, T 2000. The effects of plant flavonoids on mammalian cells: implications for inflammation, heart disease, and cancer. Pharmacological Reviews 52, 673–751.Google ScholarPubMed
Min, BR, Hart, SP 2003. Tannins for suppression of internal parasites. Journal of Animal Science 81 (E-suppl. 2), E102–E109.Google Scholar
Nolte, DL, Provenza, FD 1992a. Food preferences in lambs after exposure to flavors in milk. Applied Animal Behaviour Science 32, 381–389.Google Scholar
Nolte, DL, Provenza, FD 1992b. Food preferences in lambs after exposure to flavors in solid foods. Applied Animal Behaviour Science 32, 337–347.CrossRefGoogle Scholar
Oliver, G, Wardle, J 1999. Perceived effects of stress on food choice. Physiology & Behavior 66, 511–515.Google Scholar
Palme, R, Robia, C, Messmann, S, Hofer, J, Mostl, E 1999. Measurement of faecal cortisol metabolites in ruminants: a non-invasive parameter of adrenocortical function. Wiener Tierarztliche Monatsschrift 86, 237–241.Google Scholar
Picman, AK 1986. Biological activities of sesquiterpene lactones. Biochemical Systematics and Ecology 14, 255–281.Google Scholar
Polivy, JC, Herman, P, Coelho, JS 2008. Caloric restriction in the presence of attractive food cues: external cues, eating, and weight. Physiology & Behavior 94, 729–733.Google Scholar
Provenza, FD 1991. Behavior and nutrition are complementary endeavors. Proceedings 2nd Grazing Livestock Nutrition Conference. Agricultural Experiment Station MP-133. Oklahoma State University, Stillwater, OK, USA, pp. 157–169.Google Scholar
Provenza, FD 1996. Acquired aversions as the basis for varied diets of ruminants foraging on rangelands. Journal of Animal Science 74, 2010–2020.CrossRefGoogle ScholarPubMed
Provenza, FD, Balph, DF 1990. Applicability of five diet-selection models to various foraging challenges ruminants encounters. In Behavioural mechanisms of food selection. NATO ASI Series G: ecological sciences (ed. Hughes RN). vol. 20, pp. 423–459. Springer-Verlag, Berlin, Heildelberg, Germany.Google Scholar
Provenza, FD, Villalba, JJ 2006. Foraging in domestic vertebrates: linking the internal and external milieu. In Feeding in domestic vertebrates: from structure to function (ed. VL Bels), pp. 210–240. CABI Publisher, Oxfordshire, UK.Google Scholar
Provenza, FD, Burritt, EA, Clausen, TP, Bryant, JP, Reichardt, PB, Distel, RA 1990. Conditioned flavor aversion: a mechanism for goats to avoid condensed tannins in blackbrush. American Naturalist 136, 810–828.CrossRefGoogle Scholar
Provenza, FD, Scott, CB, Phy, TS, Lynch, JJ 1996. Preferences of sheep for foods varying in flavors and nutrients. Journal of Animal Science 74, 2355–2361.Google Scholar
Provenza, FD, Villalba, JJ, Dziba, LE, Atwood, SB, Banner, RE 2003. Linking herbivore experience, varied diets, and plant biochemical diversity. Small Ruminant Research 49, 257–274.Google Scholar
Redbo, I, Nordblad, A 1997. Stereotypies in heifers are affected by feeding regime. Applied Animal Behaviour Science 53, 193–202.Google Scholar
Robles, M, Arguellin, M, West, J, Rodriguez, E 1995. Recent studies on zoopharmacognosy, pharmacology and neurotoxicology of sesquiterpene lactones. Planta Medica 61, 199–203.Google Scholar
Rolls, BJ 1986. Sensory-specific satiety. Nutrition Reviews 44, 93–101.Google Scholar
Rolls, BJ, Rolls, ET, Rowe, EA, Sweeney, K 1981. Sensory specific satiety in man. Physiology & Behavior 27, 137–142.CrossRefGoogle ScholarPubMed
Rolls, BJ, van Duijvenvoorde, PM, Rowe, EA 1983. Variety in the diet contributes to the development of obesity in the rat. Physiology & Behavior 30, 21–27.Google Scholar
Rosenthal, GA, Janzen, DH 1979. Herbivores: their interaction with secondary plant metabolites. Academic Press, New York, NY, USA.Google Scholar
Rutter, SM 2006. Diet preference for grass and legumes in free-ranging domestic sheep and cattle: current theory and future application. Applied Animal Behaviour Science 97, 17–35.Google Scholar
Schepetkin, IA, Quinn, MT 2006. Botanical polysaccharides: macrophage immunomodulation and therapeutic potential. International Immunopharmacology 6, 317–333.CrossRefGoogle ScholarPubMed
Schwartzkopf-Genswein, K, González, L, Gibb, D, McAllister, T 2009. Application of feeding behavior as an indicator of pain and morbidity in feedlot cattle. Journal of Animal Science 87 (E-suppl. 2/J), 319.Google Scholar
Scott, LL, Provenza, FD 1998. Variety of foods and flavors affects selection of foraging locations by sheep. Applied Animal Behaviour Science 61, 113–122.CrossRefGoogle Scholar
Scott, LL, Provenza, FD 1999. Variation in food selection among lambs: effects of basal diet and foods offered in a meal. Journal of Animal Science 77, 2391–2397.Google Scholar
Smith, J, Boyd, K 1991. Lives in the Balance. Oxford University Press, Oxford, UK.Google Scholar
Sowell, BF, Bowman, JGP, Branine, ME, Hubbert, ME 1998. Radio frequency technology to measure feeding behavior and health of feedlot steers. Applied Animal Behaviour Science 59, 277–284.Google Scholar
Swithers, SE, Hall, WG 1994. Does oral experience terminate ingestion ? Appetite 23, 113–138.CrossRefGoogle ScholarPubMed
Tizard, IR, Carpenter, RH, McAnalley, BH, Kemp, MC 1989. The biological activities of mannans and related complex carbohydrates. Molecular Biotherapy 1, 290–296.Google ScholarPubMed
Van Roijen, J 1991. Predictability and boredom. Applied Animal Behaviour Science 31, 283–287.CrossRefGoogle Scholar
Van Vuuren, AM, Meijas, JAC 1987. Effects of herbage composition and supplement feeding on the excretion on nitrogen dung and urine by grazing cows. In Animal manure on grassland and forage crops (ed. Van der Meer), pp. 17–25. Martinus Nijhoff, Dordrecht, Netherlands.Google Scholar
Villalba, JJ, Provenza, FD 1996. Preference for flavored wheat straw by lambs conditioned with intraruminal administrations of sodium propionate. Journal of Animal Science 74, 2362–2368.Google Scholar
Villalba, JJ, Provenza, FD 1997a. Preference for wheat straw by lambs conditioned with intraruminal infusions of starch. The British Journal of Nutrition 77, 287–297.Google Scholar
Villalba, JJ, Provenza, FD 1997b. Preference for flavored foods by lambs conditioned with intraruminal administrations of nitrogen. The British Journal of Nutrition 78, 545–561.Google Scholar
Villalba, JJ, Provenza, FD 1999. Nutrient-specific preferences by lambs conditioned with intraruminal infusions of starch, casein, and water. Journal of Animal Science 77, 378–387.CrossRefGoogle ScholarPubMed
Villalba, JJ, Provenza, FD 2007. Self-medication and homeostatic behaviour in herbivores: learning about the benefits of nature’s pharmacy. Animal 1, 1360–1370.Google Scholar
Villalba, JJ, Provenza, FD 2009. Learning and dietary choice in herbivores. Rangeland Ecology & Management In Press.Google Scholar
Villalba, JJ, Provenza, FD, Hall, JO, Lisonbee, LD 2009a. Selection of tannins by sheep in response to gastro-intestinal nematode infections. Journal of Animal Science 87 (E-suppl. 2/J), 494.Google Scholar
Villalba, JJ, Manteca, X, Provenza, FD 2009b. Relationship between reluctance to eat novel foods and open-field behavior in sheep. Physiology & Behavior 96, 276–281.Google Scholar
Waghorn, GC 1990. Beneficial effects of low concentrations of condensed tannins in forages fed to ruminants. In Microbial and plant opportunities to improve lignocellulose utilization by ruminants (ed. DE Akin, LG Ljungdahl, JR Wilson and PJ Harris), pp. 137–247. Elsevier Science Publishing Co., New York, NY, USA.Google Scholar
Westoby, M 1974. An analysis of diet selection by large generalist herbivores. American Naturalist 108, 290–304.Google Scholar
Westoby, M 1978. What are the biological bases of varied diets? American Naturalist 112, 627–631.Google Scholar
Wilmshurst, JF, Fryxell, JM, Hudson, RJ 1995. Forage quality and patch choice by wapiti (Cervus elaphus). Behavioral Ecology 6, 209–217.Google Scholar
Zobel, G, Schwartzkopf-Genswein, KS, Veira, DM, Genswein, BMA, Zobel, AM, Gibb, DJ, von Keyserlingk, MAG 2006. Beef feedlot cattle prefer more forage in their ration when given a choice. Canadian Journal of Animal Science 86, 596–597 (abstract).Google Scholar