Fecha/hora: 03/06/2024 05:43:40

Biblioteca(s): 	INIA Las Brujas.	
Fecha corriente: 	19/07/2023	
Fecha de la última actualización: 	19/07/2023	
Autoria: 	SANTANA, A.; CAJARVILLE, C.; MENDOZA, A.; REPETTO, J.L.	
Afiliación: 	A. SANTANA, Departamento de Producción Animal y Salud de los Sistemas Productivos (IPAV), Facultad de Veterinaria, Universidad de la República, San José, 801000, Uruguay; CECILIA CAJARVILLE, Departamento de Producción Animal y Salud de los Sistemas Productivos (IPAV), Facultad de Veterinaria, Universidad de la República, San José, 801000, Uruguay; ALEJANDRO FRANCISCO MENDOZA AGUIAR, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay; JOSÉ LUIS REPETTO, Departamento de Producción Animal y Salud de los Sistemas Productivos (IPAV), Facultad de Veterinaria, Universidad de la República, San José, 801000, Uruguay.	
Título: 	Including 8 hours of access to alfalfa in 1 or 2 grazing sessions in dairy cows fed a partial mixed ration: Effects on intake, behavior, digestion, and milk production and composition.	
Año de publicación: 	2023	
Fuente/Imprenta: 	Journal of Dairy Science. 2023, https://doi.org/10.3168/jds.2022-22743  --- [In Press, Corrected Proof]. OPEN ACCESS.	
ISSN: 	0022-0302	
DOI: 	10.3168/jds.2022-22743	
Idioma: 	Inglés	
Notas: 	Article history: Received 8 September 2022; Accepted 3 March 2023; Available online 18 July 2023. -- Correspondence author: : joselorepetto@gmail.com -- LICENSE: This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). -- FUNDING: This experiment was partially supported by the Agencia Nacional de Innovación e Investigación of Uruguay (Grant FMV_3-2018-1-148846 to A. Santana). --	
Contenido: 	The aim of this study was to evaluate the inclusion of alfalfa grazing during 8 h continuous or partitioned in 2 separated sessions of 4 h after each milking, on nutrient intake, digestibility, ruminal fermentation, feeding behavior, milk production, milk composition, and milk fatty acid profile, in late-lactation cows fed a partial mixed ration (PMR). Twelve dairy cows (193 ± 83 d in milk, 584 ± 71 kg of body weight) were housed in individual outdoor pens and assigned to treatments according to a 3 × 3 Latin square design replicated 4 times. The treatments were as follows: (1) control (T0), cows were fed a total mixed ration (TMR) provided ad libitum 20.0% crude protein (CP), 32.2% neutral detergent fiber (NDF); (2) fed a diet combining a PMR which had the same ingredient composition as the TMR (60% of ad libitum intake) + 1 session of 8 h of pasture (T8), continuous grazing alfalfa (Medicago sativa; 20.6% CP, 35.8% NDF) after the p.m. milking; and (3) PMR (60% of ad libitum intake) + 2 daily sessions of 4 h of access to pasture after each milking (T4+4). The experiment lasted 57 d and was divided into 3 periods of 19 d each. The first 12 d of each period was used for diet adaptation, and the last 7 d was used for data collection. No differences among treatments were observed for any of the productive variables, feeding efficiency, or purine derivatives excretion. Cows in T0 had greater intake and apparent digestibility of dry matter, organic matter, and nonfibrous carbohydrates compared with T4+4 and T8. Compared with T0, alfalfa grazing increased the concentration of C18:1 trans-11 and decreased those of C16:0 and C17:0 in milk fat. Cows in T4+4 consumed 1.1 more kg DM/d of alfalfa and N provided by alfalfa in the diet was 3 percentage points higher compared with T8 cows (266 vs. 229 g/d, respectively). In addition, T4+4 cows had a greater daily range of ruminal pH than T8 (0.73 vs. 0.93), and the highest concentrations of NH3-N were recorded during the a.m. grazing session while in T8 cows it occurred during the night. In conclusion, including 8 h of alfalfa grazing in T8 and T4+4 treatments allowed the substitution between 35.8 and 38.7% of the total dry matter intake (DMI) of a PMR (with a similar CP concentration to alfalfa) for pasture, maintaining milk solids production and increasing the C18:1 trans-11 of milk fat compared with a TMR in mid late-lactation cows. In an herbage plus PMR diet, splitting the 1 continuous grazing session of 8 h into 2 sessions of 4 h increased the proportion of energy and N provided by alfalfa pasture and reduced PMR intake, without modifying the total nutrient intake or productive performance of cows. © 2023, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®	
Palabras-Clave: 	Fresh forage; Partial mixed ration; Ruminal fermentation.	
Thesagro: 	ALFALFA.	
Categoría del tema: 	L02 Alimentación animal	
URL: 	https://www.sciencedirect.com/science/article/pii/S0022030223003740/pdf	
Registro original: 	INIA Las Brujas (LB)	
Ejemplares: 	LB - (103605-1) - PXI - AP - DD - Journal of Dairy Science/2023 -  -  - DIS