Improving the performance of dairy cattle with a xylanase-rich exogenous enzyme preparation.

Autor:	Romero JJ; Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32608., Macias EG; Departamento de Zootecnia, Universidad Nacional Agraria La Molina, Lima, Lima 12, Peru., Ma ZX; Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32608., Martins RM; Departamento de Zootecnia, Universidade Federal de Viçosa, Viçosa, 36570, Brazil., Staples CR; Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32608., Beauchemin KA; Agriculture and Agri-Food Canada, Lethbridge Research Center, Lethbridge, AB T1J 4B1, Canada., Adesogan AT; Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville 32608. Electronic address: adesogan@ufl.edu.
Jazyk:	angličtina
Zdroj:	Journal of dairy science [J Dairy Sci] 2016 May; Vol. 99 (5), pp. 3486-3496.
DOI:	10.3168/jds.2015-10082
Abstrakt:	The objective of this experiment was to examine effects of adding 2 exogenous fibrolytic enzymes (EFE) to the total mixed ration (TMR) on the performance of lactating dairy cows (experiment 1) and the kinetics of ruminal degradation of the diet (experiment 2). Twelve EFE had been screened in a series of in vitro assays that identified the most potent EFE and their optimal doses for increasing the digestibility of bermudagrass. In experiment 1, 66 Holstein cows (21±5 d in milk) were grouped by previous milk production and parity (45 multiparous and 21 primiparous) and assigned randomly to 1 of the following 3 treatments: (1) control (CON, untreated), (2) Xylanase Plus [2A, 1mL/kg of TMR dry matter (DM); Dyadic International, Jupiter, FL], and (3) a 75:25 (vol/vol) mixture of Cellulase Plus and Xylanase Plus EFE (3A, 3.4mL/kg of TMR DM; Dyadic International). The EFE were sprayed twice daily onto a TMR (10% bermudagrass silage, 35% corn silage, 5% alfalfa-orchardgrass hay mixture, and 50% concentrates; DM basis) and fed for a 14-d training and covariate period and a 70-d measurement period. Experiment 2 aimed to examine the in situ DM ruminal degradability and ruminal fermentation measurements of the diets fed in experiment 1. Three ruminally fistulated lactating Holstein cows were assigned to the diets. The experiment had a 3×3 Latin square design with 23-d periods. In experiment 1, application of 2A increased intakes (kg/d) of DM (23.5 vs. 22.6), organic matter (21.9 vs. 20.9), and crude protein (3.9 vs. 3.7) and tended to increase yields (kg/d) of fat-corrected milk (41.8 vs. 40.7) and milk fat (1.48 vs. 1.44). In particular, 2A increased milk yield (kg/d) during wk 3 (41.2 vs. 39.8, tendency), 6 (41.9 vs. 40.1), and 7 (42.1 vs. 40.4), whereas 3A increased milk yield (kg/d) during wk 6 (41.5 vs. 40.1, tendency), 8 (41.8 vs. 40.0), and 9 (40.9 vs. 39.5, tendency). In experiment 2, EFE treatment did not affect ruminal DM degradation kinetics or ruminal pH, ammonia-N, and volatile fatty acid concentration. Application of 2A to the bermudagrass-based TMR increased DM intake and milk production, implying that this EFE could be used to increase the performance of lactating dairy cows fed diets containing up to 10% bermudagrass. (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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