Effects of dietary crude protein concentration on late-lactation dairy cow performance and indicators of nitrogen utilization

Journal of Dairy Science
T BarrosM A Wattiaux

Abstract

The objectives of this study were to measure performance responses and to evaluate indictors of N utilization in late-lactation cows fed diets with incremental reductions in crude protein (CP) concentration. Holstein cows (n = 128; 224 ± 54 d in milk) were stratified by parity and days pregnant (86 ± 25 d) and randomly assigned to 1 of 16 pens in a randomized complete block design. For 3 wk, all cows received a covariate diet containing 16.9% CP [dry matter (DM) basis]. For the subsequent 12 wk, pens were randomly assigned to 1 of 4 treatments that contained 16.2, 14.4, 13.1, or 11.8% CP (DM basis). Diets were offered once daily and contained 32.5% corn silage, 32.5% alfalfa silage, 13.5% high-moisture corn, and 21.5% concentrate mix. A reduction in dietary CP was achieved by replacing soybean meal with soy hulls in the concentrate mix (DM basis). Dry matter intake, milk urea N (MUN; mg/dL), and the yield of milk urea N (g/d) decreased linearly with dietary CP. Compared with a 16.2% CP diet, a 14.4% CP diet did not alter milk yield throughout the study, but the 13.1 and 11.8% CP diets reduced milk yield after 4 and 1 wk, respectively. Furthermore, milk protein percentage was reduced for all dietary CP less than 16.2%, but this ...Continue Reading

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Citations

Nov 6, 2018·Journal of Dairy Science·T Amirabadi FarahaniM Kazemi-Bonchenari
Jul 4, 2019·Anais Da Academia Brasileira De Ciências·Patrícia CeolinNair H Kawashita
Sep 18, 2020·Tropical Animal Health and Production·Sirley Carrillo-HernándezCarlos Manuel Arriaga-Jordán
Aug 22, 2021·Tropical Animal Health and Production·Muhammad Uzair AkhtarMuhammad Naveed-Ul-Haque
Nov 12, 2021·Tropical Animal Health and Production·Dixan Pozo-LeyvaCarlos Manuel Arriaga-Jordán

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