Luebbe Kelsey M, Stalker Leslie A, Klopfenstein Terry J, Funston Richard N
Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE.
West Central Research and Extension Center, University of Nebraska-Lincoln, North Platte, NE.
Transl Anim Sci. 2019 Jul 12;3(4):1492-1501. doi: 10.1093/tas/txz116. eCollection 2019 Jul.
A 4-yr experiment examined how weaning date and prepartum nutrition affected productivity in a spring (March and April) calving system. Crossbred beef cows (479 ± 59 kg, = 144) were used in a completely randomized design with a 2 × 4 factorial treatment arrangement: 1) cows were weaned in early October or early December; and 2) during late gestation cows were fed on a dry matter basis a 32% crude protein supplement at 0, 0.41, or 0.82 kg/cow/d on dormant upland range or grazed corn residue without supplement. Cow body condition score (BCS) was affected ( ≤ 0.01) by treatment prior to parturition and breeding but was similar ( > 0.27) among all treatments in October. Dams on a higher nutritional plane during winter treatment had greater ( < 0.01) BCS and body weight (BW) prior to parturition and breeding. Subsequent pregnancy rates (88% to 97%) were not influenced ( > 0.76) by weaning date, but tended ( = 0.10) to be lower for cows grazing winter range without supplement. Calves born to dams grazing winter range without supplement had lower ( < 0.01) BW in October and adjusted weaning BW. Pre-breeding BW of heifers weaned in December born to cows grazing winter range without supplement was lower ( < 0.01) than contemporaries born to cows in all other treatment combinations. However, postweaning (0.48 kg/d) and postbreeding (0.42 kg/d) average daily gain, percentage cycling before breeding (33%), and pregnancy rate (81%) was similar ( > 0.12). Within weaning date, steers born to cows grazing winter range without supplement had lower ( < 0.05) hot carcass weight (HCW) than contemporaries born to cows grazing corn residue. Cows weaned in December had decreased BW and BCS but similar pregnancy rates as cows weaned in October. Weaning date and dam maternal nutrition had minimal impact on heifer progeny pregnancy rate. Steer progeny born to dams on a higher nutritional plane had similar HCW at slaughter when adjusted to equal fat thickness.
一项为期4年的试验研究了断奶日期和产前营养如何影响春季（3月和4月）产犊系统的生产性能。采用完全随机设计，选用杂交肉牛母牛（体重479±59千克，n = 144），采用2×4析因处理安排：1）母牛在10月初或12月初断奶；2）在妊娠后期，母牛在休耕的高地牧场按干物质基础饲喂粗蛋白含量为32%的补充料，每头母牛每天分别为0、0.41或0.82千克，或放牧玉米秸秆而不补充饲料。产前和配种前，母牛的体况评分（BCS）受处理影响（P≤0.01），但10月份所有处理间相似（P>0.27）。冬季处理时营养水平较高的母牛在产前和配种前具有更高（P<0.01）的BCS和体重（BW）。随后的妊娠率（88%至97%）不受断奶日期影响（P>0.76），但未补充饲料放牧冬季牧场的母牛妊娠率有降低趋势（P = 0.10）。未补充饲料放牧冬季牧场的母牛所产犊牛在10月份和校正断奶体重时体重较低（P<0.01）。12月断奶的小母牛，其母亲在未补充饲料放牧冬季牧场的情况下所产的小母牛，配种前体重低于（P<0.01）所有其他处理组合的母牛所产的同期小母牛。然而，断奶后（0.48千克/天）和配种后（0.42千克/天）的平均日增重、配种前发情比例（33%）和妊娠率（81%）相似（P>0.12）。在同一断奶日期内，未补充饲料放牧冬季牧场的母牛所产公牛犊的热胴体重（HCW）低于（P<0.05）放牧玉米秸秆的母牛所产的同期公牛犊。12月断奶的母牛体重和BCS下降，但妊娠率与10月断奶的母牛相似。断奶日期和母牛母体营养对小母牛后代妊娠率影响极小。营养水平较高的母牛所产公牛犊在屠宰时，调整到相同脂肪厚度后，热胴体重相似。
