Lactational performance of dairy cows in response to supplementing N-acetyl-l-methionine as source of rumen-protected methionine.

Autor:	Amaro FX; Department of Animal Sciences, University of Florida, Gainesville 32611., Kim D; Department of Animal Sciences, University of Florida, Gainesville 32611., Restelatto R; Department of Animal Sciences, University of Florida, Gainesville 32611; Universidade Federal do Parana, Curitiba, PR, 80060, Brazil., Carvalho P; Department of Animal Sciences, University of Florida, Gainesville 32611; Institute of Agriculture and Environmental Sciences, Federal University of Mato Grosso, Sinop, MT, 78557, Brazil., Arriola K; Department of Animal Sciences, University of Florida, Gainesville 32611., Duvalsaint EJC; Department of Animal Sciences, University of Florida, Gainesville 32611., Cervantes AP; Department of Animal Sciences, University of Florida, Gainesville 32611., Jiang Y; Department of Animal Sciences, University of Florida, Gainesville 32611., Agarussi MCN; Department of Animal Sciences, University of Florida, Gainesville 32611; Universidade Federal de Vicosa, Vicosa, MG, 36570, Brazil., Silva VP; Department of Animal Sciences, University of Florida, Gainesville 32611; Universidade Federal de Vicosa, Vicosa, MG, 36570, Brazil., Adesogan AT; Department of Animal Sciences, University of Florida, Gainesville 32611., Ferraretto LF; Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison 53706., Staples CR; Department of Animal Sciences, University of Florida, Gainesville 32611., Eun JS; BIO Research Institute, CJ CheilJedang, Suwon, 04560, South Korea., Moon JO; BIO Research Institute, CJ CheilJedang, Suwon, 04560, South Korea., Vyas D; Department of Animal Sciences, University of Florida, Gainesville 32611. Electronic address: diwakarvyas@ufl.edu.
Jazyk:	angličtina
Zdroj:	Journal of dairy science [J Dairy Sci] 2022 Mar; Vol. 105 (3), pp. 2301-2314. Date of Electronic Publication: 2021 Dec 23.
DOI:	10.3168/jds.2021-21068
Abstrakt:	The objective of this experiment was to evaluate the effects of supplementing a rumen-protected source of Met, N-acetyl-l-methionine (NALM), on lactational performance and nitrogen metabolism in early- to mid-lactation dairy cows. Sixty multiparous Holstein dairy cows in early lactation (27 ± 4.3 d in milk, SD) were assigned to 4 treatments in a randomized complete block design. Cows were blocked by actual milk yield. Treatments were as follows: (1) no NALM (control); (2) 15 g/d of NALM (NALM15); (3) 30 g/d of NALM (NALM30); and (4) 45 g/d of NALM (NALM45). Diets were formulated using a Cornell Net Carbohydrate and Protein System (CNCPS) v.6.5 model software to meet or exceed nutritional requirements of lactating dairy cows producing 42 kg/d of milk and to undersupply metabolizable Met (control) or supply incremental amounts of NALM. The digestible Met (dMet) supply for control, NALM15, NALM30, and NALM45 were 54.7, 59.8, 64.7, and 72.2 g/d, respectively. The supply of dMet was 88, 94, 104, and 115% of dMet requirement for control, NALM15, NALM30, and NALM45, respectively. Milk yield data were collected, dry matter intake (DMI) was measured daily, and milk samples were collected twice per week for 22 wk. Blood, ruminal fluid, urine, and fecal samples were collected during the covariate period and during wk 4, 8, and 16. Data were analyzed using the GLIMMIX procedure of SAS (SAS Institute) using covariates in the model for all variables except body weight. Linear, quadratic, and cubic contrasts were also tested. Treatments did not affect DMI, milk yield, and milk component concentration and yield; however, feed efficiency expressed as milk yield per DMI and 3.5% fat-corrected milk per DMI were quadratically affected, with greater response observed for NALM15 and NALM30 compared with control. Acetate proportion linearly increased, whereas propionate proportion linearly decreased with NALM supplementation. Blood urea nitrogen linearly decreased with NALM supplementation. Total plasma essential AA concentrations were quadratically affected, as greater values were observed for control and NALM45 than other treatments. Plasma Met concentration was quadratically affected as lower levels were observed with NALM15, whereas Met concentrations increased with NALM45 compared with control. Nitrogen utilization efficiency and apparent total-tract nutrient digestibility were not affected by treatment. Supplementation of NALM at 15 or 30 g/head per day resulted in the greatest improvements in feed efficiency without affecting N metabolism of early- to mid-lactation dairy cows. (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
Databáze:	MEDLINE
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