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Levels and degradability of crude protein in digestive metabolism and performance of dairy cows

Alves, Bruna Gomes and de Magalhães Rodrigues Martins, Cristian Marlon and Oliveira De Sousa, Dannylo and Arcari, Marcos André and Rennó, Francisco Palma and Santos, Marcos Veiga (2020). Levels and degradability of crude protein in digestive metabolism and performance of dairy cows. Brazilian journal of veterinary research and animal science. 57 , e168157
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Abstract

Two experiments were conducted to evaluate the effect of the level and degradability of crude protein (CP) on the digestive metabolism and productive performance of dairy cows. In both experiments, 15 Holstein cows with 585 ± 40 kg of body weight were distributed in a Latin square design with five contemporary squares, three periods of 21 days and three treatments. In experiment 1, treatments consisted of three CP levels (130, 160 or 180 g CP/kg DM), while in experiment 2, the treatments consisted of three levels of rumen degradable protein (RDP; 80, 100 or 120 g RDP/kg DM) in diets with average of 163 g CP/kg DM. Variables evaluated in both experiments were dry matter intake (DMI), total apparent digestibility, milk yield (MY) and composition, ruminal fermentation and N balance. In experiment 1, the increase of CP from 130 to 180 linearly increased the organic matter, CP, neutral detergent fiber (NDF) and acid detergent fiber (ADF) intake (kg) and the apparent total digestibility coefficient of DM and CP. In addition, a linear increase of MY, fat corrected milk (FCM) and daily production of fat, protein, lactose, casein and total solids was observed. A linear increase in ruminal ammoniacal nitrogen (NH 3 -N) concentration and nitrogen excretion in milk, feces and urine was also observed. However, there was no observed effect on SCFA concentration. In experiment 2, the increase of the RDP from 80 to 120 increased the DMI, MY, FCM, milk protein content and digestibility coefficient of the NDF, ADF and ethereal extract. Additionally, there was an increase in NH 3 -N concentration and milk nitrogen excretion. The studies indicated that the increase of CP content up to 100 g RDP/kg DM increased the DMI and the productive performance of the cows, but also increased urine N. Thus, it is desirable that the increase of the CP through the increase of the RDP is carried out up to 100 g of RDP/kg DM, since there is elimination of nitrogen, decrease of milk yield and decrease of propionic acid in values above that level.

Authors/Creators:Alves, Bruna Gomes and de Magalhães Rodrigues Martins, Cristian Marlon and Oliveira De Sousa, Dannylo and Arcari, Marcos André and Rennó, Francisco Palma and Santos, Marcos Veiga
Title:Levels and degradability of crude protein in digestive metabolism and performance of dairy cows
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Dois experimentos foram realizados com o objetivo de avaliar o efeito do nível e da degradabilidade da proteína bruta (PB) no metabolismo digestivo e no desempenho produtivo de vacas leiteiras. Nos dois experimentos, 15 vacas da raça Holandesa com 585 ± 40 kg de peso corporal foram distribuídas em delineamento do tipo quadrado latino com cinco quadrados contemporâneos, sendo três períodos de 21 dias e três tratamentos. No experimento 1, os tratamentos consistiram de três níveis de PB (130, 160 ou 180 g CP/kg de MS), enquanto que no experimento 2, os tratamentos consistiram de três níveis de proteína degradável no rúmen (PDR; 80, 100 ou 120 g de PDR/kg MS) em dietas com média de 163 g CP/kg MS. As variáveis avaliadas nos dois experimentos foram: consumo de matéria seca (CMS), digestibilidade aparente total, produção e composição do leite (PL), fermentação ruminal e balanço de N. No experimento 1, o aumento da PB de 130 para 180 aumentou linearmente o consumo de matéria orgânica, PB, fibra detergente neutro (FDN), fibra em detergente ácido (ADF) (kg) e o aparente coeficiente de digestibilidade total de MS e PB. Além disso, foi observado um aumento linear da PL, leite corrigido para gordura (LCG) e produção diária de gordura, proteína, lactose, caseína e sólidos totais. Também foi observado aumento linear na concentração de nitrogênio amoniacal ruminal (N-NH 3 ) e excreção de nitrogênio no leite, fezes e urina. No entanto, não foi observado efeito na concentração de ácidos graxos de cadeia curta. No experimento 2, o aumento do PDR de 80 para 120 aumentou o CMS, PL, LCG, teor de proteína do leite e o coeficiente de digestibilidade do FDN, FDA e extrato etéreo. Além disso, houve aumento na concentração de N-NH 3 e excreção de nitrogênio no leite. Os estudos indicaram que o aumento do teor de PB em até 100 g RDP/kg de MS aumentou o CMS e o desempenho produtivo das vacas, mas também aumentou o N urinário. Assim, é desejável que o aumento da PB através do aumento da PDR seja realizado até 100 g de PDR/kg de MS, uma vez que há eliminação de nitrogênio, diminuição da produção de leite e diminuição do ácido propiônico em valores acima desse nível. Palavras-chave: Digestibilidade. Balanço de N. Proteína. Proteína degradável no rúmen. Fermentação ruminal.

Series Name/Journal:Brazilian journal of veterinary research and animal science
Year of publishing :2020
Volume:57
Article number:e168157
Number of Pages:11
Publisher:Faculdade de Medicina Veterinaria e Zootecnia, USP
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial-Share Alike 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Food Science
Keywords:Digestibility, N balance, Protein, Rumen-degradable protein, Ruminal fermentation
URN:NBN:urn:nbn:se:slu:epsilon-p-109625
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-109625
Additional ID:
Type of IDID
DOI10.11606/issn.1678-4456.bjvras.2020.168157
ID Code:21245
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Animal Environment and Health
Deposited By: SLUpub Connector
Deposited On:15 Jan 2021 13:03
Metadata Last Modified:18 Feb 2021 08:26

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