Abstract：
Milk production and overall dairy farm economics depend on rearing dairy heifers. This study investigated the presence of a genotype by environment interaction in Holstein (HOL), Nordic Red Dairy Cattle (RDC), and their F1 crossbreeds (HOLxRDC) when provided different feed rations. The aim of our study was to assess how different energy concentrations in feed rations affect growth, body condition scores, feed intake, and feed efficiency in the 3 groups during the prepubertal period. The 3 breed groups were randomly allocated to receive either a standard or a low energy feed ration. HOL heifers exhibited reduced growth and a lower body condition score when they were fed the low energy feed ration. In contrast, the RDC heifers demonstrated similar growth rates with the different feed rations and maintained similar body condition scores irrespective of feed energy concentration. HOLxRDC crossbred heifers performed as an intermediate between the HOL and RDC groups. There were significant differences in dry matter intake and energy intake in the HOL and HOLxRDC groups depending on feed ration treatment. The RDC heifers had similar feed intake irrespective of treatment. There were no significant differences in the feed conversion ratio between breeds and feed treatments. These results indicate the presence of a genotype by environment interaction in prepubertal HOL and RDC heifers in response to differences in feed ration treatment. Due to the influence of prepubertal growth on future milk production, reproduction, and health status, it is important to be aware of breed-specific requirements during the prepubertal period, particularly in mixed-breed and crossbred groups, to optimize growth rates and production potential.
摘要：
牛奶生产和整个奶牛场经济取决于饲养母牛。这项研究调查了荷斯坦（HOL）中环境相互作用基因型的存在，北欧红奶牛(RDC),和他们的F1杂交品种（HOLxRDC），当提供不同的饲料口粮时。我们研究的目的是评估饲料中不同的能量浓度如何影响生长，身体状况评分,饲料摄入量，青春期前3组的饲料效率。随机分配3个品种组，分别接受标准或低能量饲料定量。HOL小母牛饲喂低能量饲料时，其生长速度降低，身体状况评分降低。相比之下,RDC母牛在不同的饲料配给下表现出相似的生长速率，并且无论饲料能量浓度如何，都保持相似的身体状况评分。HOLxRDC杂交母牛是HOL和RDC组之间的中间体。HOL和HOLxRDC组的干物质摄入量和能量摄入量存在显着差异，具体取决于饲料配给处理。无论处理如何，RDC母牛的采食量都相似。品种和饲料处理之间的饲料转化率没有显着差异。这些结果表明，由于饲料配给处理的差异，青春期前HOL和RDC母牛中环境相互作用存在基因型。由于青春期前生长对未来产奶量的影响，繁殖，和健康状况，重要的是要意识到品种在青春期前的具体要求，特别是在混种和杂交群体中，优化增长率和生产潜力。
