Soriano F D, Polan C E, Miller C N
Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061-0315, USA.
J Dairy Sci. 2001 Nov;84(11):2460-8. doi: 10.3168/jds.S0022-0302(01)74696-6.
Beginning in September 1997, a 6-week study was conducted to compare performance and income-over-feed cost of lactating Holsteins cows fed either a total mixed ration diet (TMR) only, compared to TMR in the afternoon and pasture in the morning, or TMR in the morning and pasture in the afternoon. Fifty-four Holstein cows in midlactation, averaging 28.1 kg/d of milk, were used in the study. Cows were on pasture for 8 h/d after either the p.m. or the a.m. milking. Predominantly orchardgrass with lesser amounts of white clover and Kentucky bluegrass were grazed. Pasture was sampled once per week, and weekly composites were analyzed. Compressed sward height and herbage dry matter (DM) yield were estimated once per week. Milk yield was electronically recorded and was sampled biweekly. Body condition score and body weight (BW) was recorded at the beginning and end of the study. Income-over-feed cost was calculated for each treatment. Compressed sward height and DM yield averaged 12.7 cm and 1397 kg/ha, respectively. Pasture crude protein, neutral detergent fiber, and acid detergent fiber averaged 27.0, 55.7, and 26.9%, respectively, and net energy-lactation was 1.65 Mcal/kg of dry matter. Milk production was greater for cows on the TMR treatment (29.1 vs. 28.2 and 27.6). No significant difference occurred in percentage of milk fat (3.54, 3.42, and 3.46%), or protein (3.28, 3.20, and 3.22%) for the above respective treatments. The SNF content (8.77 vs. 8.67 and 8.63%) was higher in TMR cows. While BW change did not differ among treatments (23, 32, and 22 kg), body condition score change was greater in cows fed TMR only (0.14 vs. -0.06 and 0.01). As expected, TMR intake was greatest for cows fed TMR only and lowest for cows grazing after the p.m. milking (26.6 vs. 20.3 vs. 17.5 kg/d dry matter). Income-over-feed cost differed between treatments and was approximately 18.6 and 7.5% higher for cows grazing high quality pasture during the afternoon and the morning, respectively, compared with cows on the TMR treatment.
从1997年9月开始，进行了一项为期6周的研究，以比较仅饲喂全混合日粮（TMR）的泌乳荷斯坦奶牛的生产性能和收入与饲料成本，与下午喂TMR且上午放牧、或上午喂TMR且下午放牧的情况进行对比。研究中使用了54头处于泌乳中期的荷斯坦奶牛，平均日产奶量为28.1千克。奶牛在下午或上午挤奶后在牧场放牧8小时。主要放牧果园草，还有少量白三叶和草地早熟禾。每周对牧场进行一次采样，并分析每周的混合样本。每周估计一次压缩草层高度和牧草干物质（DM）产量。通过电子记录产奶量，并每两周进行一次采样。在研究开始和结束时记录体况评分和体重（BW）。计算每种处理的收入与饲料成本。压缩草层高度和DM产量平均分别为12.7厘米和1397千克/公顷。牧场粗蛋白、中性洗涤纤维和酸性洗涤纤维平均分别为27.0%、55.7%和26.9%，泌乳净能为1.65兆卡/千克干物质。TMR处理组的奶牛产奶量更高（29.1千克/天，而另外两组分别为28.2千克/天和27.6千克/天）。上述各处理的乳脂率（分别为3.54%、3.42%和3.46%）或乳蛋白率（分别为3.28%、3.20%和3.22%）没有显著差异。TMR组奶牛的非脂固形物含量更高（分别为8.77%，另外两组为8.67%和8.63%）。虽然各处理间体重变化没有差异（分别为23千克、32千克和22千克），但仅饲喂TMR的奶牛体况评分变化更大（分别为0.14，另外两组为 -0.06和0.01）。正如预期的那样，仅饲喂TMR的奶牛TMR采食量最大，下午挤奶后放牧的奶牛采食量最低（分别为26.
