Wellnitz Krista R, Parsons Cory T, Dafoe Julia M, Boss Darrin L, Wyffels Samuel A, DelCurto Timothy, Van Emon Megan L
Department of Animal and Range Sciences, Montana State University, Bozeman, MT 59717, USA.
Northern Agricultural Research Center, Montana State University, Havre, MT 59501, USA.
Animals (Basel). 2022 Jun 30;12(13):1687. doi: 10.3390/ani12131687.
This study evaluated heifer post-weaning voluntary feed intake (g/kg BW) classification on performance and reproductive measures, as well as impacts on lifetime productivity of 519 commercial Angus beef females. Heifer post-weaning voluntary feed intake (g/kg BW) was calculated over 80 test days following weaning using GrowSafe units. Heifers were categorized based on voluntary feed intake (g/kg BW) as either low (<−0.50 SD from the mean), average (±0.50 SD from the mean), or high (>0.50 SD from the mean) within year. Cow body weight (BW) and body condition score (BCS) at breeding displayed an age effect (p < 0.001), with 2- and 3-year-old cows having lighter BW and lower BCS than 4-yr-old and older cows. Cow BW at weaning showed significance for age and intake (p < 0.001) with younger cows being lighter than older cows, while low intake classified females had greater BW at weaning compared to average and high intake females. Additionally, calf 205-d weights and calf weaning weights (p < 0.01) were significant for age with calves born from older cows weighing more than younger cows. Weaning weight ratio displayed a linear increase with increasing intake classification (p < 0.01). Heifer yearling BW was significant for intake (p < 0.01) with low and average intake heifer classifications having greater heifer yearling BW than cows that had high intake classification as a heifer. Age and intake classification did not impact (p ≥ 0.22) pregnancy status or AI conception. In summary, heifer post-weaning feed intake classification had only minor impacts compared to age effects on lifetime productivity of Angus beef females.
本研究评估了519头商业化安格斯肉牛小母牛断奶后自愿采食量（克/千克体重）分类对生产性能和繁殖指标的影响，以及对其终生生产力的影响。断奶后，使用GrowSafe设备在80个测试日内计算小母牛的断奶后自愿采食量（克/千克体重）。根据年内自愿采食量（克/千克体重），小母牛被分为低采食组（低于平均值-0.50标准差）、平均采食组（在平均值±0.50标准差范围内）或高采食组（高于平均值0.50标准差）。配种时母牛的体重（BW）和体况评分（BCS）呈现年龄效应（p<0.001），2岁和3岁的母牛体重比4岁及以上的母牛轻，体况评分也更低。断奶时母牛的体重在年龄和采食量方面具有显著差异（p<0.001），年轻母牛比年长母牛轻，而低采食组的母牛断奶时体重高于平均采食组和高采食组的母牛。此外，犊牛205日龄体重和断奶体重（p<0.01）在年龄方面具有显著差异，年长母牛所生犊牛比年轻母牛所生犊牛体重更重。断奶体重比随采食分类增加呈线性增加（p<0.01）。小母牛周岁体重在采食量方面具有显著差异（p<0.01），低采食组和平均采食组的小母牛周岁体重高于高采食组的小母牛。年龄和采食分类对妊娠状态或人工授精受孕率没有影响（p≥0.22）。总之，与年龄对安格斯肉牛小母牛终生生产力的影响相比，断奶后采食量分类的影响较小。
