摘要
This study evaluated heifer postweaning residual feed intake (RFI) classification on reproductive and performance measurements of first-, second-, and third-parity Angus beef females. We analyzed the annual, as well as, cumulative production of 347 Angus females from birth through weaning of their third calf. Heifer postweaning RFI was calculated as the actual dry matter intake minus the predicted dry matter intake based on the average daily gain of the contemporary group on an annual basis. Heifers were categorized based on RFI as either low ( +0.50 SD from the mean) within year. There was no RFI × Parity interaction (P ≥ 0.14) observed for all production/reproduction traits except for conception rates (P = 0.02). Julian birth date of cows was influenced by RFI classification (P P = 0.02) effect with high RFI cows being born earlier in the calving season than average RFI cows (71.2 vs. 75.3 d), but did not differ from low RFI cows (74.0 vs. 75.3 d). Cow birth weight, weaning weight, as well as all other cow weight and body condition measurements were not influenced by RFI classification (P ≥ 0.14). As expected, there was a linear increase in cow body weight at weaning with increasing parity (P P ≥ 0.15). Calf birth weights displayed a quadratic parity effect (P P = 0.01) with first calf heifers weaning lighter calves than second- and third-parity cows. Weaning weight ratio displayed a linear decrease with increasing parity (P P = 0.09), and a quadratic tendency for pregnancy 4 (P = 0.07) as a function of RFI classification, but no effects were observed for pregnancy 1 and 3. Cow artificial insemination conception rates differed by year of pregnancy (P P = 0.81). In summary, heifer postweaning RFI classification had minimal effects on beef cattle production and reproductive efficiency.
摘要译文
这项研究评估了Wweaning后剩余的饲料摄入量（RFI）分类，该分类是对第一，第二和第三次Angus牛肉女性的生殖和性能测量。我们分析了从出生到他们的第三只小腿断奶，分析了347位安格斯女性的年度生产。Weaning后RFI被计算为实际的干物质摄入量减去预测的干物质摄入，该干物质摄入量基于当代组的平均每日增益。一年内，根据RFI将小母牛分为低（+0.50 SD）。除了构思率（p = 0.02）外，所有生产/繁殖性状均未观察到所有生产/繁殖性状的RFI×均衡相互作用（P≥0.14）。朱利安奶牛的出生日期受RFI分类的影响（P p = 0.02）效应，高RFI母牛在产犊季节的出生比平均RFI母牛早（71.2 vs. 75.3 d），但与低RFI母牛没有区别（74.0 VS（74.0 VS）。75.3d）。牛出生体重，断奶体重以及所有其他牛体重和身体状况测量不受RFI分类的影响（P≥0.14）。不出所料，断奶时牛体重随着平价的增加而有线性增加（p≥0.15）。小腿出生体重表现出比第二和第三牛母牛的第一小牛牛奶的二次奇偶校验效应（p p = 0.01）。断奶重量比表现出随着平等性的增加（p = 0.09）的线性降低，妊娠4（p = 0.07）的二次趋势是RFI分类的函数，但没有观察到怀孕1和3的影响。妊娠年的比率有所不同（p p = 0.81）。总而言之，Weaning后RFI分类对牛牛的生产和生殖效率的影响很小。
Cory T Parsons; Julia M Dafoe; Samuel A Wyffels; Megan Van Emon; Timothy DelCurto. Impacts of heifer postweaning residual feed intake classification on reproductive and performance measurements of first-, second-, and third-parity Angus beef females[J]. Translational Animal Science, 2021,5(2)