| 저자(한글) |
Sung, Mu-Kyung,Lee, Soo-Chan,Jeong, Jae-Kwan,Choi, In-Soo,Moon, Sung-Ho,Kang, Hyun-Gu,Kim, Ill-Hwa |
| 초록 |
This retrospective study evaluated the effect of age at first calving on the productive and reproductive performance in Holstein dairy cattle. Data were collected on 2,297 lactations from 19 dairy farms, including dates of birth, insemination, pregnancy, calving, and lactation and milk production (305-day milk yield at first lactation and lifetime milk yield). Lactation data were grouped based on age at first calving into the early ( ${ leq}$ and ${ leq}$ 28 months, n = 1,268), and late ( gt; 28 months, n = 615) groups. The 305-day milk yield at first lactation was higher (p |
