Exigências nutricionais de ruminantes em ambiente climático tropical
Resumo
O diagnóstico de problemas relacionados ao desempenho animal e a tomada de decisões em sistemas de produção, requerem quantificação mais acurada dos efeitos do ambiente sobre a produção de leite ou taxa de crescimento. Tanto os efeitos diretos do ambiente quanto os indiretos demonstram grande impacto no consumo de nutrientes, exigências e utilização metabólica destes, tornando válido se considerar o papel do ambiente no manejo nutricional dos ruminantes.
Assume-se que os efeitos do ambiente são inicialmente refletidos em mudanças nas exigências de energia para mantença e no consumo de matéria seca, enquanto os impactos sobre as exigências para prenhez, crescimento e lactação são secundários, após atendimento as exigências energéticas para mantença.
A primeira parte desta obra proporciona uma fundamentação de informações que relacionam tanto os fundamentos da nutrição quanto o próprio animal ao ambiente, no sentido de esclarecer terminologias e conceitos adotados.
Na segunda parte, estão apresentadas discussões que descrevem o impacto do ambiente climático tropical sobre diversas espécies de ruminantes e são sugeridas técnicas de manejo nutricional.
As exigências nutricionais têm sido comumente estabelecidas em ambientes protegidos de extremos climáticos. Por esta razão, tais exigências são mais relevantes durante condições ambientais ótimas e menos apropriadas para animais expostos a ambientes estressantes.
Estresse é referido como uma condição ambiental adversa ao bem-estar animal, destacando-se que o estresse ambiental, em sentido mais amplo, inclui tanto aspectos físicos quanto psicológicos dos animais, embora dados relativos ao ambiente e à nutrição envolvam o ambiente climático e, em particular, o efeito do estresse térmico.
Diante do exposto, a partir de revisão relativa aos efeitos do estresse ambiental sobre as exigências nutricionais de ruminantes sob condições climáticas tropicais, identificou-se que há uma lacuna de informações relacionadas ao tema, o que torna esta obra uma sistematização de resultados de pesquisas e teorias apresentadas, com grande potencial de uso por aqueles que praticam a produção de ruminantes na faixa tropical.
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Referências
AGRICULTURAL AND FOOD RESEARCH COUNCIL. AFRC. Energy and protein requirements of ruminants. Wallingford, UK: CAB INTERNATIONAL, 1993. 159p.
AGRICULTURAL RESEARCH COUNCIL. ARC. The nutrient requirements of ruminant livestock. Slough, England: Commonwealth Agricultural Bureaux, 1980. 351p.
ALLEN, M.S. Effects of diet on short-term regulation of feed intake by lactating dairy cattle. Journal of Dairy Science, v.83, n.7, p.1598-1624, 2000.
ALVES, A.A.; SALES, R.O. Aspectos do manejo nutricional de bubalinos para abate: uma revisão. Revista Científica de Produção Animal, v.2, n.2, p.233-248, 2000.
AMES, D.R.; BRINK, D.R. Effect of temperature on lamb performance and protein efficiency ratio. Journal of Animal Science, v.44, n.1, p.136-140, 1977.
AMES, D.R.; BRINK, D.R.; SCHALLES, R.R. Relationship of temperature and ADG. Journal of Animal Science, v.41, n.1, p.262-263, 1975. (Abstr.).
AMES, D.R.; BRINK, D.R.; WILLMS, C.L. Adjusting protein in feedlot diets during thermal stress. Journal of Animal Science, v.50, n.1, p.1-6, 1980.
AMES, D.R.; NELLOR, J.E.; ADAMS, T. Energy balance during heat stress in sheep. Journal of Animal Science, v.32, n.4, p.784-788, 1971.
ARMSTRONG, D.V. Heat stress interaction with shade and cooling. Journal of Dairy Science, v.77, n.7, p.2044-2050, 1994.
ATTEBERY, J.T.; JOHNSON, H.D. Effect of environmental temperature, controlled feeding and fasting on rumen motility. Journal of Animal Science, v.29, n.5, p.734-737, 1969.
BACCARI JR., F.; JOHNSON, H.D.; HAHN, G.L. Compensatory growth of young dairy heifers subjected to heat stress. Journal of Animal Science, v.51, (Suppl. 1), p.4, 1980. (Abstr.).
BARBOSA, O.R.; CARDOSO, R.M.; COELHO DA SILVA, J.F. et al. Influência da temperatura da água de beber no desempenho de animais 7/8 Holandês-Zebu, na época do verão. I. Temperatura retal, ritmo respiratório e ingestão de água. Revista da Sociedade Brasileira de Zootecnia, v.12, n.1, p.86-96, 1983.
BARBOSA, O.R.; CARDOSO, R.M.; COELHO DA SILVA, J.F. Influência da temperatura da água de beber no desempenho de animais 7/8 Holandês-Zebu, na época do verão. II. Consumo de alimento, ganho de peso e produção de ácidos graxos voláteis. Revista da Sociedade Brasileira de Zootecnia, v.12, n.1, p.97-114, 1983.
BEEDE, D.K.; COLLIER, R.J. Potential nutritional strategies for intensively managed cattle during thermal stress. Journal of Animal Science, v.62, n.2, p.543-554, 1986.
BERMAN, A.; FOLMAN, Y.; KAIM, M. et al. Upper critical temperatures and forced ventilation effects for high-yielding dairy cows in a subtropical climate. Journal of Dairy Science, v.68, n.6, p.1488-1495, 1985.
BESSE, J. La alimentacion del ganado. Madrid: Mundi-Prensa, 1986. 379p.
BHATTACHARYA, A.N.; HUSSAIN, F. Intake and utilization of nutrients in sheep fed different levels of roughage under heat stress. Journal of Animal Science, v.38, n.4, p.877-886, 1974.
BHATTACHARYA, A.N.; UWAYJAN, M. Effect of high ambient temperature and low humidity on nutrient utilization and on some physiological responses in Awasi sheep fed different levels of roughage. Journal of Animal Science, v.40, n.2, p.320-328, 1975.
BRINK, D.R.; AMES, D.R. Effect of ambient temperature on lamb performance. Journal of Animal Science, v.41, n.1, p.264, 1975. (Abstract).
BROUWER, E. Report of subcommittee on constants and factors. Proc. of 3rd. International Symposium on Energy Metabolism, European Association of Animal Production. Publ. No. 11, p.441, 1965.
CHURCH, D.C.; POND, K.R.; POND, W.G. Basic animal nutrition and feeding. 4.ed., New York: John Wiley & Sons, 1995. 624p.
CUMMINS, K.A. Effect of dietary acid detergent fiber on responses to high environmental temperature. Journal of Dairy Science, v.75, n.6, p.1465-1471, 1992.
CUNNINGHAM, M.D.; MARTZ, F.A.; MERILAN, C.P. Effect of drinking-water temperature upon ruminant digestion, intraruminal temperature, and water consumption of nonlactating dairy cows. Journal of Dairy Science, v.47, n. , p.382-385, 1964.
DAWS, G.T.; SQUIRES, V.R. Observations on the effects of temperature and distance to water on the behaviour of Merino and Border Leicester sheep. Journal of Agricultural Science, v.82, n.3, p.383-390, 1974.
DEVENDRA, C.; BURNS, M. Goat production in the tropics. UK: Commonwealth Agricultural Bureaux, 1983. 183p.
EASTRIDGE, M.L.; BUCHOLTZ, H.F.; SLATER, A.L. et al. Nutrient requirements for dairy cattle of the National Research Council versus some commonly used ration software. Journal of Dairy Science, v.81, n.11, p.3049-3062, 1998.
ELAM, C.J. Problems related to intensive indoor and outdoor beef production systems. Journal of Animal Science, v.32, n.3, p.554-559, 1971.
FINCH, V.A. Body temperature in beef cattle: its control and relevance to production in the tropics. Journal of Animal Science, v.62, n.2, p.531-542, 1986.
FINCH, V.A.; BENNETT, I.L.; HOLMES, C.R. Sweating responses in cattle and its relation to rectal temperature, tolerance of sun and metabolic rate. Journal of Agricultural Science, v.99, p.479-487, 1982.
FORBES, J. Water intake of ewes. British Journal Nutrition, v.22, p.33, 1968.
FOX, D.G.; BLACK, J.R. A system for predicting body composition and performance of growing cattle. Journal of Animal Science, v.58, n.3, p.725-739, 1984.
FOX, D.G.; TYLUTKI, T.P. Accounting for the effects of environment on the nutrient requirements of dairy cattle. Journal of Dairy Science, v.81, n.11, p.3085-3095, 1998.
GENGLER, W.R.; MARTZ, F.A.; JOHNSON, H.D. et al. Effect of temperature on food and water intake and rumen fermentation. Journal of Dairy Science, v.53, p.434-437, 1970.
GUIMARÃES, C.M.C. Termorregulação e digestibilidade em bubalinos submetidos a duas temperaturas do ar e duas proporções de volumoso:concentrado. Lavras, MG: Universidade Federal de Lavras - UFLA, 1998. 64p. Dissertação (Mestrado em Zootecnia) - Universidade Federal de Lavras, 1998.
HAALAND, G.L., TYRRELL, H.F.; MOE, P.W. The effect of dietary protein level and cattle breed on energy utilization of corn-corn silage diets for growth assessed by respiration calorimetry. Journal of Animal Science, v.52, (Suppl. 1), p.403, 1981. (Abstr.).
HAALAND, G.L.; TYRRELL, H.F.; MOE, P.W. The effect of dietary protein and cattle breed on energy utilization for growth. Journal of Animal Science, v.51, (Suppl. 1), p.365, 1980. (Abstr.).
HAHN, G.L. Housing and management to reduce climatic impacts on livestock. Journal of Animal Science, v.52, n.1, p.175-186, 1981.
HARRIS, R.R.; YATES, H.F.; BARNETT JR., J.E. Refrigerated water for fattening steers. Journal of Animal Science, v.26, n.1, p.207-208, 1967.
HIGGINBOTHAM, G.E.; TORABI, M.; HUBER, J.T. Influence of dietary protein concentration and degradability on performance of lactating cows during hot environmental temperatures. Journal of Dairy Science, v.72, n.10, p.2554-2564, 1989.
HOFFMAN, P.C.; BREHM, N.M.; HOWARD, W.T. et al. The influence of nutrition and environment on growth of Holstein replacement heifers in commercial dairy herds. Professional Animal Science, v.10, p.59-65, 1994.
HOLTER, J.B.; WEST, J.W.; McGILLARD, M.L. Predicting ad libitum dry matter intake and yield of Holstein cows. Journal of Dairy Science, v.80, n.9, p.2188-2199, 1997.
HOLTER, J.B.; URBAN JR., W.E. Water partitioning and intake prediction in dry and lactating Holstein cows. Journal of Dairy Science, v.75, n.6, p.1472–1479, 1992.
HUBER, J.T.; HIGGINBOTHAM, G.; GOMEZ-ALARCON, R.A. et al. Heat stress interactions with protein, supplemental fat, and fungal cultures. Journal of Dairy Science, v.77, n.7, p.2080-2090, 1994.
HUBER, J.T.; HIGGINBOTHAM, G.; GOMEZ-ALARCON, R.A. et al. Heat stress interactions with protein, supplemental fat, and fungal cultures. Journal of Dairy Science, v.77, n.7, p.2080-2090, 1994.
HUERTAS, A.A.G.; COELHO DA SILVA, J.F.; CAMPOS, O.F. et al. Efeito da temperatura ambiente sobre o consumo, a digestibilidade e a retenção de nutrientes em ovinos. Revista da Sociedade Brasileira de Zootecnia, v.3, n.2, p.245-266, 1974.
ITTNER, N., KELLY, C., GUILBERT, H. Water consumption of Hereford and Brahman cattle and the effect of cooled drinking water in a hot climate. Journal of Animal Science, v.10, p.742, 1951.
JOHNSON, H.D.; VANJONACK, W.J. Effects of environmental and other stressors on blood hormone patterns in lactating cows. Journal of Dairy Science, v.59, p.1603, 1976.
JOHNSON, J.C., SOUTHWELL, B.L., GIVENS, R.L. et al. Interrelationships of certain climatic conditions and productive responses of lactating dairy cows. Journal of Dairy Science, v.45, p.695, 1962.
JOHNSTON, J.E.; HINDERY, G.A.; HILL, D.H. et al. Factors concerned in hot weather effects on growth and feed efficiency of dairy heifers. Journal of Dairy Science, v.44, n.5, p.976, 1961.
KENNEDY, P.M.; YOUNG, B.A.; CHRISTOPHERSON, R.J. Studies on the relationship between thyroid function, cold acclimation and retention time of digesta in sheep. Journal of Animal Science, v.45, n.5, p.1084-1090, 1977.
KETELAARS, J.J.M.H; TOLKAMP, B.J. Toward a new theory of feed intake regulation in ruminants. 1. Causes of differences in voluntary intake: critique of current views. Livestock Production Science, v.30, p.269-296, 1992.
KLEIBER, M. The fire of life. New York: John Wiley and Sons Inc., 1961. 428p.
LANHAM, J.K.; COPPOCK, C.E.; MILAM, K.Z. et al. Effects of drinking water temperature on physiological responses of lactating Holstein cows in summer. Journal of Dairy Science, v.69, n.4, p.1004–1012, 1986.
LAREDO, M.A.; MINSON, D.J. The voluntary intake, digestibility and retention time by sheep of leaf and stem fractions of five grasses. Australian Journal of Agricultural Research, v.24, n.6, p.875-888, 1973.
LOFGREEN, G.P.; GARRETT, W.W. A system for expressing net energy requirements and feed values for growing and finishing beef cattle. Journal of Animal Science, v.27, n.3, p.793-806, 1968.
MALOIY, G.M.O.; TAYLOR, C.R. Water requirements of African goats and haired sheep. Journal of Agricultural Science, v.77, p.203-208, 1971.
MAUST, L.E.; McDOWELL, R.E.; HOOVEN, N.W. Effect of summer weather on performance of Holstein cows in three stages of lactation. Journal of Dairy Science, v.55, n.8, p.1133-1139, 1972.
McDOWELL, R.E. HOOVEN, N.W., CAMOENS, J.K. Effect of climate on performance of Holsteins in first lactation. Journal of Dairy Science, v.59, p.956, 1976.
McDOWELL, R.E.; HERNANDEZ-URDANETA, A. Intensive systems for beef production in the tropics. Journal of Animal Science, v.41, p.1228, 1975.
McDOWELL, R.E.; LEE, D.H.K.; FOHRMAN, M.H. The measurement of water evaporation from limited areas of a normal body surface. Journal of Animal Science, v.13, p.405, 1954.
McDOWELL, R.E.; MOODY, E.G.; VAN SOEST, P.J. et al. Effect of heat stress on energy and water utilization of lactating cows. Journal of Dairy Science, v.52, n.2, p.188-194, 1969.
MERTENS, D.R.; ELY, L.O. A dynamic model of fiber digestion and passage in the ruminant for evaluating forage quality. Journal of Animal Science, v.49, n.4, p.1085-1095, 1979.
MILAM, K.Z.; COPPOCK, C.E.; WEST, J.W. et al. Effects of drinking water temperature on production responses in lactating Holstein cows in summer. Journal of Dairy Science, v.69, n.4, p.1013–1019, 1986.
MILLER, J.K.; SWANSON, E.W.; LYKE, W.A. et al. Effect of thyroid status on digestive tract fill and flow rate of undigested residues in cattle. Journal of Dairy Science, v.57, n.2, p.193-197, 1974.
MOODY, E.G.; VAN SOEST, P.J.; McDOWELL, R.E. et al. Effect of high temperature and dietary fat on performance of lactating cows. Journal of Dairy Science, v.50, n.12, p.1909-1916, 1967.
MOOSE, M.G.; ROSS, C.V.; PFANDER, W.H. Nutritional and environmental relationships with lambs. Journal of Animal Science, v.29, n.4, p.619-627, 1969.
MOUNT, L.E. Concepts of thermal neutrality. In: Heat loss from animals and man. MONTEITH, J.L., MOUNT, L.E. eds. Butterworth, London, 1974.
MURPHY, M.R.; DAVIS, C.L.; McCOY, G.C. Factors affecting water consumption by Holstein cows in early lactation. Journal of Dairy Science, v.66, n.1, p.35–38, 1983.
NATIONAL RESEARCH COUNCIL. NRC. Effect of environment on nutrient requirements of domestic animals. Washington D.C.: National Academy Press, 1981a. 152p.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient requirements of beef cattle. 4th ed. Washington, D.C.: National Academy Press, 1970. 55p.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient requirements of beef cattle. 6th ed. Rev., Washington, D.C.: National Academy Press, 2000. 232p.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient requirements of beef cattle. 5th ed., Washington, D.C.: National Academy Press, 1976.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient Requirements of Dairy Cattle. 6th.ed. Washington, D.C.: National Academy Press, 1989. 157p.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient requirements of dairy cattle. Washington, D.C.: National Academy Press, 2001. 381p.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient requirements of goats: angora, dairy, and meat goats in temperate and tropical countries. Washington, D.C.: National Academy Press, 1981b. 91p.
NATIONAL RESEARCH COUNCIL. NRC. Nutrient requirements of sheep. Washington, D.C.: National Academy Press, 1985. 99p.
NATIONAL RESEARCH COUNCIL. NRC. Nutritional energetics of domestic animals and glossary of energy terms. Washington, D.C.: National Academy Press, 1981c. 54p.
OLDHAM, J.D. Protein-energy interrelationships in dairy cows. Journal of Dairy Science, v.67, p.1090, 1984.
OLIVEIRA NETO, J.B.; MOURA, A.A.A.; NEIVA, J.N.M. et al. Indicadores de estresse térmico e utilização da somatotropina bovina (bST) em vacas leiteiras mestiças (Bos taurus x Bos indicus) no semi-árido do Nordeste. Revista Brasileira de Zootecnia, v.30, n.2, p.360-367, 2001.
OLIVEIRA, E.G.; OLIVEIRA, M.E. Comportamento e dieta de caprinos no período seco em pastagem nativa. In: SIMPÓSIO EM CIÊNCIAS AGRÁRIAS: Pesquisa com Caprinos e Ovinos no CCA, Teresina, 1992. Anais... Teresina: CCA/UFPI, 1992. p.31-39.
OLIVEIRA, J.S.; MILAGRES, J.C.; CARDOSO, R.M. et al. Comportamento de novilhas de três graus de sangue, expostas ao sol e à sombra, em Viçosa, M.G. II. Componentes sangüíneos e ganhos de peso. Revista da Sociedade Brasileira de Zootecnia, v.9, n.1, p.72-89, 1980a.
OLIVEIRA, J.S.; MILAGRES, J.C.; GARCIA, J.A. et al. Comportamento de novilhas de três graus de sangue, expostas ao sol e à sombra, em Viçosa, M.G. I. Temperatura retal e ritmo respiratório. Revista da Sociedade Brasileira de Zootecnia, v.9, n.1, p.46-71, 1980b.
ØRSKOV, E.R.; RYLE, M. Energy nutrition in ruminants. New York: Elsevier Science Publishers, 1990. 149p.
OSBOURN, D.F.; TERRY, R.A.; OUTEN, G.E. et al. The significance of a determination of cell walls as the rational basis for the nutritive evaluation of forages. Proc. 12th International Grassland Congress, v.3, p.374-380, 1974.
PENNINGTON, J.A.; VANDEVENDER, K. Heat stress in dairy cattle. University of Arkansas/Division of Agriculture/Cooperative Extension Service, 2002. 3p. . Acesso em: 6 mar. 2003.
PIRES, M.F.A; CAMPOS, A.T.; FERREIRA, A.M. Importância do conforto, ambiente e instalações no manejo de matrizes leiteiras. In: SIMPÓSIO – O AGRONEGÓCIO DO LEITE NO NORDESTE: ALTERNATIVAS TECNOLÓGIAS E PERSPECTIVAS DE MERCADO, 1988, Natal. Anais.... Natal, 1998. p.266-282.
REA, J. C.; ROSS, C.V. Effect of environmental temperature on gains feed efficiency and digestibility of feed by lambs. Journal of Animal Science, v.20, n.4, p.948-949, 1961. (Abstract).
SCHNEIDER, P.L.; BEEDE, D.K.; WILCOX, C.J. et al. Influence of dietary sodium and potassium bicarbonate and total potassium on heat-stressed lactating dairy cows. Journal of Dairy Science, v.67, n.11, p.2546-2553, 1984.
SCHRAMA, J.W. Energy Metabolism of Young Unadapted Calves. Ph.D. thesis, Department of Animal Husbandry and Department of Animal Nutrition, Wageningen, The Netherlands: Wageningen Agricultural University, 1993. 156p.
SILVA, R.G. Introdução à bioclimatologia animal. São Paulo: Nobel, 2000. 286p.
SODERQUIST, H.G.; KNOX, K.L. Temperature-energy relationships in fattening lambs. Journal of Animal Science, v.26, n.4, p.930, 1967. (Abstr.).
SOUTO, P.R.L.; MILAGRES, J.C.; COELHO DA SILVA, J.F. Consumo, digestibilidade, reações fisiológicas e componentes sangüíneos de ovinos submetidos a diferentes temperaturas e a dietas com diferentes níveis de energia. II. Reações fisiológicas. Pesquisa Agropecuária Brasileira, v.25, n.9, p.1252-1259, 1990a.
SOUTO, P.R.L.; MILAGRES, J.C.; SILVA, M.A. et al. Consumo, digestibilidade, reações fisiológicas e componentes sangüíneos de ovinos submetidos a diferentes temperaturas e a dietas com diferentes níveis de energia. I. Consumo de alimento e ingestão de água. Pesquisa Agropecuária Brasileira, v.25, n.9, p.1247-1251, 1990b.
STERMER, R.A.; BRASINGTON, C.F.; COPPOCK, C.E. et al. Effect of drinking water temperature on heat stress of dairy cows. Journal of Dairy Science, v.69, n.2, p.546–551, 1986.
STOTT, G.H. What is animal stress and how is it measured?. Journal of Animal Science, v.52, n.1, p.150-153, 1981.
TEIXEIRA, J.C.; COELHO DA SILVA, J.F.; GARCIA, J.A. et al. Exigências de energia e proteína, composição e área corporal e principais cortes de carcaça em seis grupos genéticos de bovídeos. II-Exigências de energia e proteína. Revista da Sociedade Brasileira de Zootecnia, v.16, n.2, p.181-192, 1987.
TOLKAMP, B.J.; KETELAARS, J.J.M.H. Toward a new theory of feed intake regulation in ruminants. 2. Costs and benefits of feed consumption: a optimization approach. Livestock Production Science, v.30, p.297-313, 1992.
VAN SOEST, P.J. Nutritional ecology of the ruminant. 2th ed. Ithaca, New York: Cornell University, 1994. 476p.
VON KEYSERLINGK, G.E.M.; MATHISON, G.W. The effect of ruminal escape protein and ambient temperature on the efficiency of utilization of metabolizable energy by lambs. Journal of Animal Science, v.71, n.8, p.2206-2217, 1993.
WALDO, D.R.; MILLER, R.W.; OKAMOTO, M. et al. Ruminant utilization of silage in relation to hay, pellets, and hay plus grain. Il. Rumen content, dry matter passage and water intake. Journal of Dairy Science, v.48, n.11, p.1473-1480, 1965.
WARREN, W.P.; MARTZ, F.A.; ASAY, K.H. et al. Digestibility and rate of passage by steers fed tall fescue, alfalfa and orchardgrass hay in 18 and 32 C ambient temperatures. Journal of Animal Science, v.39, n.1, p.93-96, 1974.
WEETH, H.J.; HAVERLAND, L.H. Tolerance of growing cattle for drinking water containing sodium chloride. Journal of Animal Science, v.20, n.3, p.518-521, 1961.
WELCH, J.G.; SMITH, A.M. Influence of forage quality on rumination time in sheep. Journal of Animal Science, v.28, n.6, p.813-818, 1969.
WEST, J.W. Balancing diets for dairy cattle during heat stress conditions. In: FLORIDA RUMINANT NUTRITION SYMPOSIUM, 1997, Flórida. Proceedings… Flórida: University of Florida, 1997. Disponível em: . Acesso em: 3 mar. 2003.
WEST, J.W. Interactions of energy and bovine somatotropin with heat stress. Journal of Dairy Science, v.77, n.7, p.2091-2102, 1994.
WEST, J.W.; COPPOCK, C.E.; MILAM, K.Z. et al. Potassium carbonate as a potassium source and dietary buffer for lactating Holstein cows during hot weather. Journal of Dairy Science, v.70, n.2, p.309-320, 1987.
WILKS, D.L.; COPPOCK, C.E.; LANHAM, J.K. et al. Responses of lactating Holstein cows to chilled drinking water in high ambient temperatures. J. Dairy Sci., v.73, p.1091–1099, 1990.
WINCHESTER, C.F.; MORRIS, M.J. Water intake rates of cattle. Journal of Animal Science, v.15, n.3, p.722-740, 1956.
YOUNG, B.A. Cold stress as it affects animal production. Journal of Animal Science, v.52, n.1, p.154-163, 1981.
YOUNG, B.A. Effects of winter acclimatization on resting metabolism of beef cows. Canadian Journal of Animal Science, v.55, p.619-625, 1975a.
YOUNG, B.A. Temperature-induced changes in metabolism and body weight of cattle (Bos taurus). Canadian Physiology and Pharmacology, v.53, p.947-953, 1975b.
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