Effects of lactation number and litter size on the chemical composition and immune components of goat colostrum

This study aimed to evaluate the effect of the number of lactations and litter size on the chemical composition, immunoglobulins, and cytokines of goat colostrum. The experiment was conducted at the Animal Research Base, Mianyang Academy of Agricultural Sciences, from February to March 2021. After delivery, 48 colostrum samples were obtained every 24 h by manual milking from both udders. The contents of colostrum proteins, IgA, and IgM increased markedly up to 48 h postpartum, reaching 250 and 1250 mu g/mL, respectively (p < 0.01 compared with 0 h). However, the total Ig and IgG contents dropped quickly at 48 h postpartum to around 4.5 and 6 mg/mL, respectively, and continued to do so until 96 h postpartum (p < 0.01). As for litter size, the colostrum DM, fat, total Ig, IgG, INF-gamma, and IL-2 of twin-birth goats were higher than those of single-birth goats at 0 h postpartum. Moreover, the colostrum of multiparous goats contained higher total Ig, IgA, IgG, and INF-gamma concentrations than that of primiparous goats at 0 h postpartum (p < 0.01). However, the colostrum INF-alpha and IL-5 contents of multiparous goats were lower than those of primiparous goats at 0 h postpartum (p < 0.05). Available information indicates that colostrum secretion takes place until 48 h postpartum and that the effect of litter size and lactation number on colostrum quality is observed at 0 h postpartum.