Data/hora: 21/09/2024 13:35:23

Biblioteca(s): 	Embrapa Gado de Leite.	
Data corrente: 	21/08/2023	
Data da última atualização: 	21/08/2023	
Autoria: 	MAIA, G. G.; SIQUEIRA, L. G. B.; VASCONCELOS, C. O. de P.; TOMICH, T. R.; CAMARGO, L. S. de A.; RODRIGUES, J. P. P.; MENEZES, R. A. de; GONÇALVES, L. C.; TEIXEIRA, B. F.; GRANDO, R. de O.; NOGUEIRA, L. A. G.; PEREIRA, L. G. R.	
Afiliação: 	GILSON GONÇALVES MAIA, Universidade Federal Fluminense; LUIZ GUSTAVO BRUNO SIQUEIRA, CNPGL; CARLOS OTÁVIO DE PAULA VASCONCELOS, Universidade Federal Fluminense; THIERRY RIBEIRO TOMICH, CNPGL; LUIZ SERGIO DE ALMEIDA CAMARGO, CNPGL; JOÃO PAULO PACHECO RODRIGUES, Universidade Federal do Sul e Sudeste do Pará; RAFAEL ARAÚJO DE MENEZES, Universidade Federal de Minas Gerais; LÚCIO CARLOS GONÇALVES, Universidade Federal de Minas Gerais; BRIDA FAGGION TEIXEIRA, Instituto de Desenvolvimento do Alto Uruguai; RODRIGO DE OLIVEIRA GRANDO, Instituto de Desenvolvimento do Alto Uruguai; LUIZ ALTAMIRO GARCIA NOGUEIRA, Universidade Federal Fluminense; LUIZ GUSTAVO RIBEIRO PEREIRA, CNPGL.	
Título: 	Effects of heat stress on rumination activity in Holstein-Gyr dry cows.	
Ano de publicação: 	2020	
Fonte/Imprenta: 	Livestock Science, v. 239, 104092, 2020.	
DOI: 	https://doi.org/10.1016/j.livsci.2020.104092	
Idioma: 	Inglês	
Conteúdo: 	The objective of this study was to evaluate the effects of heat stress (HS) on: i) time and daily pattern of rumination and ii) in situ degradability in Holstein-Gyr crossbred dry cows. Nine cows, weighing 556.2 ± 97.1 kg were housed in a climate chamber (average THI=83.1) or a freestall barn (average THI=66.5) randomly assigned to treatments in a crossover design. Cows were fed corn silage ad libitum and 1 kg of concentrate as a maintenance diet. To measure rumination, we used a sensor attached to a collar. The in situ ruminal degradability was evaluated by incubation of concentrate, silage, and diet samples into the rumen of a fistulated cow for 6, 24, 48 and 96 h. The RT was affected by HS (P<0.001) and time of the day (P<0.001). The rumination pattern for control and HS cows had a first peak at approximately 04:00h and the magnitude of this peak in HS was 22.9% less than controls. The second RT peak occurred in the evening (~20:00h), when RT in HS was 27.8% less compared with controls. We observed a reduction in dry matter digestibility (DMD) of concentrate (85.1% vs 77.8%, control and HS, respectively; P<0,05) and also in the slow-degradable fraction of concentrate (93.9% vs 85.1%, respectively; P<0,05). Finally, DMD of the diet reduced from 73% to 70% for animals exposed to HS compared to controls. In conclusion, HS negatively affected e rumination time and in situ ruminal degradability in dry dairy cows.	
Palavras-Chave: 	Câmara climatizada; Cinética ruminal; THI.	
Thesagro: 	Bovino; Digestibilidade; Gado Gir; Gado Holandês; Vaca Leiteira.	
Categoria do assunto: 	L Ciência Animal e Produtos de Origem Animal	
Registro original: 	Embrapa Gado de Leite (CNPGL)	
Exemplares: 	CNPGL - (26076-1) - UPC - AP - DD -  -  -  - DIS