Increasing dietary concentrate levels for Nellore of three sexual categories: intake, partial and total tract digestibility, microbial protein synthesis and ruminal metabolism

Revista Brasileira de Zootecnia

Paulino, Pedro Veiga Rodrigues¹  Azevêdo, José Augusto Gomes²  Valadares Filho, Sebastião de Campos³  Véras, Robson Magno Liberal¹  Detmann, Edenio³  Marcondes, Marcos Inácio¹  Barbosa, Analívia Martins¹ 

[1] UFV;Universidade Estadual de Santa Cruz, Ilhéus;Universidade Federal de Viçosa

关键词: bull;    heifer;    ruminal ammonia;    ruminal pH;    steer   Introdução O rebanho bovino nacional é composto aproximadamente por 165 milhões de cabeças;    dos quais 33;    5 milhões são novilhas e 31;    5 milhões;    novilhos de 1 a 3 anos (Anualpec;    2005);   

DOI  :  10.1590/S1516-35982008000500025

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

Twelve Nellore of three sexual categories (four heifers, four bulls and four steers) averaging 15 months of age and body weight of 235, 249, and 239 kg, respectively, were assigned to a completely randomized design with a 2 × 3 factorial arrangement (two levels of concentrate –25 or 50% and three sexual categories) to evaluate intake, partial and total digestibility of nutrients, microbial protein synthesis and ruminal metabolism. The collection of ruminal fluid was done before and at 2, 4, and 6 hours post-feeding to determine pH and ammonia concentration. With the exception of EE, no other significant effect of concentrate levels and sexual categories was observed on intake and partial or total tract digestibility of nutrients. The intakes of DM, OM, EE, CP, NFC, and TDN (kg/day) and DM (% BW or g/kg0.75) were affected neither by the concentrate levels nor by sexual category. Increasing dietary concentrate levels decreased NDF digestibility. Average bacterial N contents ranged from 6.91 to 7.39. No significant effect of concentrate levels and sexual category was observed on duodenal flow of nutrients and microbial efficiency excepted when expressed as gNmic/kgOMDR. Maximum ruminal NH3 concentration (14.55 mg/dL) was estimated at 1.83 hours after-feeding. It was concluded that increasing dietary concentrate levels did not affect intake, partial and total tract digestibility of most nutrients and microbial protein synthesis.

【 授权许可】

CC BY-NC