Fuerniss Luke K, Young J Daniel, Hall Jerica R, Wesley Kaitlyn R, Benitez Oscar J, Corah Larry R, Rathmann Ryan J, Johnson Bradley J
Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX 79409, USA.
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66502, USA.
Transl Anim Sci. 2023 Aug 14;7(1):txad096. doi: 10.1093/tas/txad096. eCollection 2023.
Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to characterize the effects of beef or dairy maternal genetics and the dairy management system on calf growth. Pregnancies were created with a 2 × 2 factorial arrangement of dam breed (Holstein or Jersey) and mating type (artificial insemination or implantation of an in vitro produced embryo from a commercial beef cow oocyte). Resulting calves were reared in a calf ranch. Additionally, commercial beef cows were inseminated and reared resulting calves on range. Therefore, the five treatments were Angus × Holstein (A × H; = 19), Angus × Jersey (A × J; = 22), Angus × beef gestated by Holstein (H ET; = 18), Angus × beef gestated by Jersey (J ET; = 8), and Angus × beef raised by beef (A × B; = 20). Beginning at birth, calf body weight, cannon circumference, forearm circumference, top width, hip width, and hip height were measured approximately every 28 d until ~196 d of age. At birth, A × J calves weighed the least (< 0.01). At 150 d of age, body weight was greatest (< 0.05) among A × B calves, intermediate among H ET and A × H calves, and least among J ET and A × J calves (< 0.05). Morphometric differences were detected between treatments (multivariate analysis of variance, < 0.01). Primary discriminant function scores identified A × B calves having lesser values than A × J or A × H calves (analysis of variance [], < 0.01); A × B calves had greater cannon circumference, greater top width, and less hip height (standardized loadings of -0.47, -0.48, and 0.63, respectively). Secondary discriminant function scores identified J ET and H ET to have greater forearm circumference-a key indicator of muscling-than A × J or A × H (ANOVA, < 0.01; standardized loading of 0.99). The dairy management system limited growth rate of beef genetics compared to the beef management system. In addition, Holstein dams transmitted greater growth potential than Jersey dams. Replacing maternal dairy genetics with beef genetics moderated frame size and created a more muscular phenotype.
改良的繁殖管理已使奶牛妊娠能针对肉牛生产进行优化。这项由父本控制的研究目的是描述肉牛或奶牛母本遗传因素以及奶牛养殖系统对犊牛生长的影响。妊娠通过母本品种（荷斯坦牛或泽西牛）与配种类型（人工授精或植入来自商业肉牛母牛卵母细胞的体外生产胚胎）的2×2析因设计来实现。所产犊牛在犊牛养殖场饲养。此外，对商业肉牛母牛进行授精，并在牧场饲养所产犊牛。因此，有五种处理方式：安格斯×荷斯坦（A×H；n = 19）、安格斯×泽西（A×J；n = 22）、由荷斯坦牛孕育的安格斯×肉牛（H ET；n = 18）、由泽西牛孕育的安格斯×肉牛（J ET；n = 8）以及由肉牛饲养的安格斯×肉牛（A×B；n = 20）。从出生开始，大约每隔28天测量犊牛体重、管围、前臂围、顶宽、臀宽和臀高，直至约196日龄。出生时，A×J犊牛体重最轻（P<0.01）。在150日龄时，A×B犊牛体重最大（P<0.05），H ET和A×H犊牛体重居中，J ET和A×J犊牛体重最轻（P<0.05）。各处理组之间检测到形态测量差异（多变量方差分析，P<0.01）。主判别函数得分显示，A×B犊牛的值低于A×J或A×H犊牛（方差分析[F值]，P<0.01）；A×B犊牛管围更大、顶宽更大且臀高更小（标准化载荷分别为 -0.47、-0.48和0.63）。次判别函数得分显示，J ET和H ET的前臂围（肌肉发育的关键指标）大于A×J或A×H（方差分析，P<0.01；标准化载荷为0.99）。与肉牛养殖系统相比，奶牛养殖系统限制了肉牛遗传因素的生长速度。此外，荷斯坦牛母本传递的生长潜力大于泽西牛母本。用肉牛遗传因素取代母本奶牛遗传因素可适度减小体格大小并形成更具肌肉的表型。
