Passive immunity in lambs: Serum lactoferrin concentrations as a predictor of IgG concentration and its relation to health status from birth to 12 weeks of life

This study was designed to evaluate the potential of lactoferrin (Lf) as predictor of passive immunity by establishing correlation between serum Lf and IgG concentration determined by ELISA in healthy lambs before and after colostrum intake at various days of neonatal period, to determine the presumptive effect of serum Lf along with serum IgG levels on lamb health through comparison of values measured for healthy and diseased lambs and to evaluate the impact of colostral Lf concentrations on passive immunity and lamb health. For this purpose, blood samples were obtained from the fifty healthy lambs at birth and 1, 2, 4, 7, 14 and 28 days after birth. Additionally first day blood samples were also collected from 286 lambs. Health status of all lambs (n = 336) was monitored from birth to 12 weeks of life. Colostrum samples were obtained within 0–4 h of parturition from 193 the ewes related to the lambs tested in this study. Serum Lf and IgG concentrations of day 1, 2, 4, 7, 14 and 28 were significantly higher than the values of pre-suckling time in healthy lambs. There was a weak linear relationship between serum Lf and IgG concentrations in only 1, 2, 4 and 7 day-old healthy lambs (R2 = 0.073–0.079) except for the first day (R2 = 0.213). The multiple linear regression model moderately (R2 = 0.375) estimated the serum IgG concentration as a function of the serum Lf concentration and of the age of lambs at the time of sampling [day 1, 2, 4, 7, 14 and 28] in healthy lambs during the neonatal period. The healthy lambs had significantly higher Lf concentration at 24th hour after the birth (SLfC-24) than ill lambs in the neonatal period (P < 0.01) and the period covering 5–12 weeks of life (P < 0.01). Similar results were found for SIgGC-24. The morbidity rate of lambs with SLfC-24 <800 ng/mL was 3.2 times higher in neonatal period and 1.7 times higher in the period covering 5–12 weeks of life when compared with lambs having SLfC-24 above 800 ng/mL. There was a significant (P < 0.01) and positive (R = 0.261) correlation between CIgGC and CLfC. In conclusion, our study revealed the importance of serum Lf in prevention of disease development in lambs and in prediction of passive immunity. In addition, the positive correlation between colostral Lf and IgG values may be of use in evaluation of colostrum quality.