Fecha/hora: 15/06/2024 23:57:49

Biblioteca(s): 	INIA La Estanzuela.	
Fecha corriente: 	03/09/2019	
Fecha de la última actualización: 	28/04/2021	
Autoria: 	RABAZA, A.; BANCHERO, G.; CAJARVILLE,C.; ZUNINO, P.; BRITO, A.; REPETTO, J.; FRAGA, M.	
Afiliación: 	ANA VIRGINIA RABAZA MARTINEZ, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay; GEORGGET ELIZABETH BANCHERO HUNZIKER, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay; CECILIA CAJARVILLE, Departamento de Nutrición Animal, Facultad de Veterinaria, Universidad de la República, San José, Uruguay; PABLO ZUNINO, MEC/ IIBCE (Instituto de Investigaciones de Ciencias Biológicas "Clemente Estable"), Montevideo, Uruguay.; Departamento de Nutriciion Animal, Instituto de Produccion  Animal, Facultad de Veterinaria, Universidad de la República, Ruta 1 km 42.5, San José 80100, Uruguay.; JOSE LUIS REPETTO CAPELLO, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay.//Departamento de Bovinos, Instituto de Producción Animal, Facultad de Veterinaria, Universidad de la República, Ruta 1 km 42, CP 80100 San José, Uruguay.; MARTIN FRAGA COTELO, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay.	
Título: 	Effects of feed withdrawal duration on animal behaviour, rumen microbiota and blood chemistry in feedlot cattle: implications for rumen acidosis.	
Año de publicación: 	2019	
Fuente/Imprenta: 	Animal,  Volume 14 , Issue 1 , January 2020 , pp. 66 - 77. DOI: https://doi.org/10.1017/S1751731119001538	
DOI: 	10.1017/S1751731119001538	
Idioma: 	Inglés	
Notas: 	Article history: Received 22 October 2018 // Accepted 13 June 2019.	
Contenido: 	Abstracts: Feed withdrawal ( FW ) is a frequent issue in open outdoor feedlot systems, where unexpected circumstances can limit the animals? access to food. The relationship among fasting period, animal behaviour during feed reintroduction ( FR ) and acidosis occurrence has not been completely elucidated. Twenty steers fitted with rumen catheters were fed a high-concentrate diet (concentrate : forage ratio 85 : 15) and were challenged by a protocol of FW followed by FR. The animals were randomly assigned to one of the four treatments: FW for 12 h ( T12 ), 24 h ( T24 ), 36 h ( T36 ) or no FW (control group) followed by FR. The steers? behaviour, ruminal chemistry, structure of the ruminal microbial community, blood enzymes and metabolites and ruminal acidosis status were assessed. Animal behaviour was affected by the FW?FR challenge (P<0.05). Steers from the T12, T24 and T36 treatments showed a higher ingestion rate and a lower frequency of rumination. Although all animals were suspected to have sub-acute ruminal acidosis ( SARA ) prior to treatment, a severe case of transient SARA arose after FR in the T12, T24 and T36 groups. The ruminal pH remained below the threshold adopted for SARA diagnosis (pH value=5.6) for more than three consecutive hours (24, 7 and 19 h in the T12, T24 and T36 treatments, respectively). The FW?FR challenge did not induce clinical acute ruminal acidosis even though steers from the T36 treatment presented ruminal pH values that were consistent with this metabolic disorder (pH threshold for acute acidosis=5.2). Total mixed ration reintroduction after the withdrawal period reactivated ruminal fermentation as reflected by changes in the fermentation end-products. Ruminal lactic acid accumulation in steers from the T24 and T36 treatments probably led to the reduction of pH in these groups. Both the FW and the FR phases may have altered the structure of the ruminal microbiota community. Whereas fibrolytic bacterial groups decreased relative abundance in the restricted animals, both lactic acid producer and utiliser bacterial groups increased (P<0.05). The results demonstrated a synchronisation between Streptococcus (lactate producer) and Megasphaera (lactate utiliser), as the relative abundance of both groups increased, suggesting that bacterial resilience may be central for preventing the onset of metabolic disturbances such as ruminal acidosis. A long-FW period (36 h) produced rumen pH reductions well below and lactic acid concentration increased well above the accepted thresholds for acute acidosis without any perceptible clinical signs.	
Palabras-Clave: 	ACIDOSIS RUMINAL; ENGORDE DE BOVINOS; FATTENING; FOOD RESTRICTION; LIVESTOCK; PLATAFORMA DE SALUD ANIMAL; RESTRICCIÓN NUTRICIONAL; RUMINAL ENVIRONMENT; SUB-ACUTE RUMINAL ACIDOSIS.	
Thesagro: 	COMPORTAMIENTO ANIMAL; GANADO BOVINO.	
Categoría del tema: 	L02 Alimentación animal	
Registro original: 	INIA La Estanzuela (LE)	
Ejemplares: 	LE - (102975-1) - PXI - AP - DD - PP/ANIMAL/2020 -  -  - DIS