摘要
This study aimed to quantify the relationship between residual feed intake (RFI) measured in 500 heifers and subsequently as mid-gestation cows at the Roy Berg Kinsella Research Station (KIN;n= 227) and Lacombe Research and Development Centre (LRDC;n= 273). Heifers were initially tested for RFI adjusted for end of test rib fat (RFIfat) at 8–12 months of age and then again as 3-year-old first-calf heifers at KIN and as 4–13-year-old cows at LRDC. Heifer RFIfatmeasured in drylot on a forage diet was associated (R2> 0.53;P< 0.001) with RFIfatmeasured again as older cows. Each 1 kg DM day−1change in heifer RFIfatequaled 0.48 ± 0.10 and 0.75 ± 0.19 kg DM day−1change in cow RFIfatfor KIN and LRDC, respectively. Linear effects were also reported for RFIfatcomponent traits, where DMI (P< 0.001), ADG (P< 0.060), mid-test metabolic weight (P< 0.001), and end of test rib fat (P< 0.001) measured as heifers were related when measured again as older cows. In addition, the linear effects of heifer RFIfaton cow RFIfatwere constant across cow age groups from 4–10 years of age. These results show that selection for RFI in heifers will result in cows that are also more feed efficient.
摘要译文
本研究旨在量化在Roy Berg Kinsella研究站（KIN；n=227）和Lacombe研发中心（LRDC；n=273）测量的500头小母牛和随后作为中期妊娠母牛的剩余摄食量（RFI）之间的关系。 在8-12月龄时，最初检测小母牛的RFI（根据试验结束肋骨脂肪（RFIfat）进行调整），然后在KIN作为3岁初犊小母牛和4-13岁母牛在LRDC再次检测。 饲喂饲料的干奶牛群中测定的小母牛RFIfat与年龄较大的奶牛再次测定的RFIfat相关（R2>0.53；P<0.001）。 对于KIN和LRDC,小母牛RFI中每1 kg DM第1天变化分别相当于0.48±0.10和0.75±0.19 kg DM第1天变化。 还报告了RFI组分性状的线性效应，其中DMI（P< 0.001）、ADG（P< 0.060）、试验中期代谢重量（P< 0.001）和试验结束肋骨脂肪（P< 0.001）作为小母牛再次测量时相关。 此外，小母牛RFIfaton奶牛RFIfat的线性效应在4-10岁奶牛年龄组中保持恒定。 这些结果表明，在小母牛中选择RFI将导致奶牛的饲料效率更高。
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