Feed restriction of F1 Holstein × Zebu cows in the final third of lactation modifies intake, nutrient digestibility, feeding behavior, and performance

ABSTRACT The objective of this study was to evaluate the effect of quantitative feed restriction level on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance of F1 Holstein × Zebu cows in late lactation. Sixty F1 Holstein × Zebu cows were used at the stage of late lactation (183.0±17.5 days of lactation) and with initial body weight (BW) of 499±30 kg. The experimental arrangement adopted was the completely randomized design, with five feed restriction levels (3.39, 2.75, 2.50, 2.25, and 2.00% of BW) and twelve cows as replicates for each treatment. The roughage:concentrate ratio was of 75:25 in the total dry matter of the diet. The restriction of dietary supply from 3.39 to 2.0% of BW linearly reduced dry matter intake by 51.74%. The restriction in diet supply linearly increased dry matter digestibility in 13.76%. For each 1% BW restriction in the diet supply for the animals, there was a linear reduction of 3 h in feeding time. Restriction in diet supply of crossbred cows from 3.39 to 2.0% of BW reduced milk production by 24.84%. For each 1% restriction on supply, 2.17 L of milk were not produced. Milk production corrected to 3.5% fat was not altered with the feed restriction. Final BW decreased 41 kg for each percentage unit of diet restriction. Feed efficiency increased 28.72% with feed restriction. For F1 Holstein × Zebu cows in the late lactation, the restriction of dietary supply up to 2.0% of body weight decreases nutrient intake, nitrogen balance, rumination time, and milk production; however, it improves nutrient digestibility and feed efficiency of the animals.

摘要 本研究旨在评估定量饲料限制水平对泌乳后期F1荷斯坦牛×瘤牛（F1 Holstein × Zebu）的营养摄入量与消化率、氮平衡、饲养效率、采食行为及生产性能的影响。本试验选用60头处于泌乳后期（泌乳天数183.0±17.5 d）、初始体重（BW, Body Weight）为499±30 kg的F1荷斯坦牛×瘤牛。试验采用完全随机设计，设置5个饲料限制水平（分别为体重的3.39%、2.75%、2.50%、2.25%及2.00%），每个处理组设置12头试验牛作为重复。试验日粮总干物质（dry matter）中粗精比为75:25。当日粮饲喂量从体重的3.39%降至2.0%时，试验牛的干物质采食量呈线性下降51.74%；干物质消化率则随饲料限制水平提升呈线性增加13.76%。试验动物的日粮饲喂量每降低体重的1%，其采食时间线性减少3 h。F1荷斯坦牛×瘤牛的日粮饲喂量从3.39%体重降至2.0%体重时，产奶量下降24.84%；饲喂量每降低1%，则少产奶2.17 L。乳脂率校正为3.5%的产奶量未受饲料限制的影响。试验牛的最终体重随日粮限制比例每提升1个单位，便降低41 kg。饲料转化效率随饲料限制提升28.72%。综上，对于泌乳后期的F1荷斯坦牛×瘤牛，将日粮饲喂量限制至体重的2.00%及以下，会降低试验牛的营养摄入量、氮平衡、反刍时间及产奶量，但可改善其营养消化率与饲料转化效率。