摘要
Abstract
Serum immunoglobulin G(IgG)concentration after birth is an important indicator of passive im-munity acquisition in calves and the immune health status of dairy herds.To systematically characterize the variation in serum IgG concentration and identify its influencing factors under large-scale dairy farm condi-tions,this study was conducted on a dairy farm in northern Jiangsu Province.A total of 1 952 serum sam-ples were collected from Holstein calves born from 2021 to 2025,of which 1 098 valid samples were re-tained after quality control.Serum IgG concentration was measured using a handheld refractometer,and multifactorial analysis of variance was performed to evaluate the effects of parity,gestation length,age at IgG measurement,birth weight,maternal dry period length,birth year,and birth season on calf serum IgG concentration.The results showed that the overall concentration of IgG in calf serum was approximately normally distributed,with an average of(6.38±0.53)mg/mL,and mainly concentrated within the range of 6.0-7.0 mg/mL.Both birth year and birth season had highly significant effects on the serum IgG concen-tration of calves(P≤0.01),with calves born in autumn exhibiting relatively higher serum IgG concentra-tions.In contrast,parity,gestation length,age at IgG measurement,birth weight,and maternal dry period length had no significant effects on serum IgG concentration(P＞0.05).However,correlation analysis re-vealed a significant positive correlation between maternal dry period length and calf serum IgG concentra-tion(P ≤ 0.05).These findings provide a scientific basis for the immune health assessment and calf-rearing management of calf breeding in dairy farms.关键词
荷斯坦犊牛/血清IgG/被动免疫/影响因素Key words
Holstein calves/serum IgG/passive immunity/influencing factors分类
农业科技
