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):1704. doi: 10.3390/ani12131704.
Heifer post-weaning intake classification was utilized to evaluate subsequent intake and performance measurements of 2-, 5-, and 8-year-old lactating and non-lactating Angus females. For both studies, heifers were categorized based on voluntary feed intake (expressed as 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 one year. Intake and production data of pregnant, non-lactating (n = 59; Study 1) and lactating, non-pregnant (n = 54; Study 2) females were evaluated. Heifer post-weaning voluntary feed intake was calculated over 80 test days post-weaning using GrowSafe feed intake units. Cow body-weight (BW) for non-lactating cows showed a tendency for age × intake interaction (p = 0.10), with older cows weighing more than younger cows. Milk production expressed as kilograms and g/kg BW of the cow had an age × intake (p < 0.001) effect. Two-year-old cows with low- and average-intake classifications had greater milk production (p < 0.001) and milk produced expressed as g/kg BW (p < 0.001) than 2-year-old cows with high-intake classifications. Additionally, 5-year-old cows with average and high-intake classifications had greater milk production (p < 0.001) and g/kg BW (p < 0.001) compared to 5-year-old cows classified as low-intake. In summary, heifer post-weaning intake classification had minor impacts on performance measurements in the three age classes of beef females at two different production levels.
利用断奶后小母牛的采食量分类来评估2岁、5岁和8岁泌乳及非泌乳安格斯母牛随后的采食量和生产性能指标。在两项研究中，小母牛根据自愿采食量（以克/千克体重表示）在一年内分为低采食组（低于平均值−0.50标准差）、中等采食组（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）。对怀孕非泌乳（n = 59；研究1）和泌乳未怀孕（n = 54；研究2）母牛的采食量和生产数据进行了评估。断奶后小母牛的自愿采食量是在断奶后的80个测试日使用GrowSafe采食量测定装置计算得出的。非泌乳母牛的体重显示出年龄×采食量交互作用的趋势（p = 0.10），年龄较大的母牛比年龄较小的母牛体重更重。以千克和克/千克体重表示的母牛产奶量存在年龄×采食量（p < 0.001）效应。低采食组和中等采食组的2岁母牛比高采食组的2岁母牛产奶量更高（p < 0.001），且以克/千克体重表示的产奶量也更高（p < 0.001）。此外，中等采食组和高采食组的5岁母牛比低采食组的5岁母牛产奶量更高（p < 0.001），且克/千克体重产奶量也更高（p < 0.001）。总之，断奶后小母牛的采食量分类对处于两种不同生产水平的三个年龄组肉牛母牛的生产性能指标影响较小。
