Gedye Kristene, Notcovich Shirli, Correa-Luna Martin, Ariyarathne Pavithra, Heiser Axel, Lopez-Lozano Raquel, Lopez-Villalobos Nicolas
School of Veterinary Sciences, Massey University, Palmerston North, New Zealand.
School of Agriculture and Environment, Massey University, Palmerston North, New Zealand.
Anim Sci J. 2020 Jan-Dec;91(1):e13331. doi: 10.1111/asj.13331.
This study evaluated the concentration and expression of lactoferrin (LF) in cows selected for once a day (OAD) milking compared to twice a day (TAD) milking. Milk samples were collected from the Massey University TAD and OAD herds. Milk traits and expression of LF and insulin-like growth factor 1 (IGF-1) were analyzed with a general linear model that included the fixed effects of milking frequency, lactation number, interaction between milking frequency and lactation number, and as covariates proportion of F, heterosis F × J and deviation from the herd median calving date. Cows milked OAD produced milk with higher (p < .01) concentrations of protein and lactose than TAD milked cows. Compared to TAD cows, cows milked OAD had higher expression of the LF gene (1.40 vs. 1.29 folds, p = .03) and the IGF-1 gene (1.69 vs. 1.48 folds, p = .007). The correlation between the expression of LF gene and the concentration of LF in milk was strong (r = .66 p < .001), but the correlation between the expression of the IGF-1 gene and LF concentration was stronger (r = .94, p < .001). These results suggest that milking frequency affects the milk composition and expression of milk composition genes at early lactation.
本研究评估了与一天两次挤奶（TAD）的奶牛相比，选择一天一次挤奶（OAD）的奶牛中乳铁蛋白（LF）的浓度和表达情况。从梅西大学的TAD和OAD牛群中采集了牛奶样本。采用一般线性模型分析了牛奶性状以及LF和胰岛素样生长因子1（IGF-1）的表达，该模型包括挤奶频率、泌乳次数、挤奶频率与泌乳次数之间的相互作用等固定效应，以及作为协变量的F比例、杂种优势F×J和与牛群中位数产犊日期的偏差。与TAD挤奶的奶牛相比，OAD挤奶的奶牛所产牛奶的蛋白质和乳糖浓度更高（p <.01）。与TAD奶牛相比，OAD挤奶的奶牛LF基因的表达更高（分别为1.40倍和1.29倍，p = 0.03），IGF-1基因的表达也更高（分别为1.69倍和1.48倍，p = 0.007）。LF基因表达与牛奶中LF浓度之间的相关性很强（r = 0.66，p <.001），但IGF-1基因表达与LF浓度之间的相关性更强（r = 0.94，p <.001）。这些结果表明，挤奶频率会影响泌乳早期的牛奶成分和牛奶成分基因的表达。
