ABSTRACT The aim of this study was to compare conformation, age at puberty and subsequent milk production of Holstein–Friesian–Jersey crossbred heifers grown in a linear trajectory (Target; n = 55) between 6- and 15-month target liveweights (LWT), with heifers grown in a seasonal manner (Seasonal; n = 55) of slow over first winter and fast over spring. Heifers that grew to Target attained puberty 38 days earlier than heifers that grew in a seasonal manner; however, no difference between treatments in the date of first calving occurred. Heifers in the seasonal treatment were 1 cm (P = .032) taller than those in the target treatment, but similar in girth and length. There was no effect of treatment on first lactation milk production. These results suggest that provided heifers reached their pre-mating target LWT, the growth trajectory between target LWT at 6 and 15 months of age did not negatively impact frame size or first lactation milk production.

中文翻译：

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奶牛的线性增长与季节性增长降低了青春期的年龄，但不影响第一次泌乳的产奶量

摘要 本研究的目的是比较在 6 个月和 15 个月的目标活重 (LWT) 之间以线性轨迹（目标；n = 55）生长的荷斯坦 - 弗里斯兰 - 泽西杂交小母牛的构象、青春期年龄和随后的产奶量, 小母牛以季节性方式（季节性；n = 55）生长，在第一个冬天缓慢而在春天快速。生长到 Target 的小母牛比季节性生长的小母牛提前 38 天进入青春期；然而，第一次产犊日期的处理之间没有差异。季节性处理中的小母牛比目标处理中的小母牛高 1 厘米 (P = .032)，但周长和长度相似。治疗对第一次泌乳的泌乳量没有影响。这些结果表明，只要小母牛达到交配前的目标 LWT，