目的是评估单独提供饲料原料(SF)和浓缩物喂养频率与提供TMR的影响,关于泌乳性能,瘤胃发酵,肠道CH4排放,营养素消化率,N使用效率,牛奶脂肪酸简介,和泌乳中期奶牛的血液变量。在研究开始时,将24头荷斯坦奶牛(12头初生和12个多胎)平均(±SD)141±35DIM和43±6kg/d的产奶量(MY)用于重复的3×3拉丁方设计实验,每个实验3个周期28d,由7天组成,用于适应饮食,11d用于估计净能量和可代谢蛋白质需求,10d用于数据和样本收集。奶牛根据奇偶校验进行分组,DIM,和我成4个拉丁方块。治疗分配平衡了遗留效应,将正方形内的奶牛分配到(1)随意饲喂TMR的基础日粮;(2)以SF饲喂随意饲喂的牧草和以3×/d(SF×3)喂养的浓缩物;(3)以SF饲喂的基础日粮,以随意饲喂的牧草和以6×/d(SF×6)饲喂的浓缩物。与TMR相比,SF使总QI降低1.2kg/d。治疗没有影响我的,牛奶成分,或ECM产量,与TMR相比,除了牛奶脂肪浓度降低和牛奶尿素N增加SF×3外。在SF中,饲料效率(MY/DMIkg)提高了7%,与TMR相比。乙酸盐的瘤胃摩尔比例和乙酸盐与丙酸盐的比例降低,与TMR和SF×6相比,SF×3增加了丙酸的摩尔比例。SF的每日CH4产量下降了9%,与TMR相比。在本研究中,肠溶CH4产量(每千克的DMI)不受处理的影响。在SF中,每公斤MY的甲烷强度倾向于降低10%,与TMR相比。奇数和支链的总和,奇数链,和安替苏牛奶脂肪酸倾向于或被SF增加,与TMR相比。营养素的摄入量倾向于或被SF减少,与TMR相比。在SF中,淀粉酶处理的NDF的消化率趋于降低,ADF的消化率降低了3%,与TMR相比。尿液和粪便N排泄物不受治疗影响。占总氮摄入量的百分比,单独提供饲料原料增加了牛奶N的分泌,表明SF提高了N的使用效率,与TMR相比。相对于TMR,SF降低了血液总脂肪酸浓度。与TMR和SF×6相比,SF×3增加了血尿素氮浓度。总的来说,通过单独提供饲料原料,提高了饲料和氮素的利用效率,并且增加浓缩物饲喂的频率可促进与通过饲喂TMR获得的效果相似的瘤胃发酵效果。
The objective was to evaluate the effects of separate offering of feed ingredients (SF) and frequency of concentrate feeding versus offering a TMR, on lactational performance, ruminal fermentation, enteric CH4 emissions, nutrient digestibility, N use efficiency, milk fatty acid profile, and blood variables in mid-lactation dairy cows. Twenty-four Holstein cows (12 primi- and 12 multiparous) averaging (±SD) 141 ± 35 DIM and 43 ± 6 kg/d of milk yield (MY) at the beginning of the study were used in a replicated 3 × 3 Latin square design experiment with 3 periods of 28 d each, composed of 7 d for adaptation to the diets, 11 d for estimation of net energy and metabolizable protein requirements, and 10 d for data and samples collection. Cows were grouped based on parity, DIM, and MY into 4 Latin squares. Treatment allocation was balanced for carryover effects, and cows within square were assigned to (1) basal
diet fed ad libitum as TMR; (2) basal
diet fed as SF with forages fed ad libitum and concentrates fed 3×/d (SF×3); or (3) basal
diet fed as SF with forages fed ad libitum and concentrates fed 6×/d (SF×6). Compared with TMR, SF decreased total DMI by 1.2 kg/d. Treatments did not affect MY, milk components, or ECM yield, except for a decrease in milk fat concentration and an increase in milk urea N by SF×3, compared with TMR. Feed efficiency (kg of MY/kg of DMI) was increased by 7% in SF, compared with TMR. Ruminal molar proportion of acetate and acetate-to-propionate ratio were decreased, whereas molar proportion of propionate was increased by SF×3, compared with TMR and SF×6. There was a 9% decrease in daily CH4 production by SF, compared with TMR. Enteric CH4 yield (per kg of DMI) was not affected by treatments in the current study. Methane intensity per kilogram of MY tended to be decreased by 10% in SF, compared with TMR. The sums of odd- and branched-chain, odd-chain, and anteiso milk fatty acids tended to be or were increased by SF, compared with TMR. Intake of nutrients tended to be or were decreased by SF, compared with TMR. The digestibility of amylase-treated NDF tended to be decreased and ADF digestibility was decreased by 3% in SF, compared with TMR. Urinary and fecal N excretions were not affected by treatments. As a percentage of total N intake, separate offering of feed ingredients increased milk N secretion, indicating an increased N use efficiency by SF, compared with TMR. Blood total fatty acid concentration was decreased by SF relative to TMR. Compared with both TMR and SF×6, SF×3 increased blood urea N concentration. Overall, feed and N use efficiencies were increased by separate offering of feed ingredients, and increasing the frequency of concentrate feeding promoted ruminal fermentation effects similar to those obtained by feeding a TMR.