形態・生理

[VII-20-06] Effect of milking time on yield, composition and antimicrobial component in milk of lactating goats

*Zi-Long Liang¹, Naoki Suzuki¹, Takahiro Nii¹, Naoki Isobe¹ (1. Hiroshima Univ.)

[Objectives] Various studies have attempted to improve the milk yield and composition in dairy cows. However, no study has examined the effects of milking at different times on the yield and composition of milk. Therefore, the present study was conducted to compare yield, composition and antimicrobial component of milk among milking at different time in lactating goats. [Methods] Eight goats were milked at different times for three weeks (1st wk: 6:00, 2nd wk: 9:00, 3rd wk: 12:00). The light ranged from 6:30 to 19:00. Milk and blood samples were collected. [Results] Milking at 9:00 showed a significantly higher milk yield than that at 6:00 and 12:00. The prolactin levels in plasma and fat, Na⁺, and S100A7 (antimicrobial component) in milk were lowest when milking at 9:00. There was a significant negative correlation between prolactin concentration and milk yield. These results indicate that milk yield, composition, and antimicrobial components can be affected by milking time, which may be related to the altered concentration of prolactin in the blood.