Perinatal adrenocortical function in relation to the growth rate and immunoglobulin acquisition of goat kids

Abstract

Serum cortisol concentration at birth can reflect the prenatal adrenocortical function of young animals. Its relation with the growth rate and serum γ-globulin levels during the first 5 days of post-natal life was studied in full-term and eutocial goat kids. Two groups of kids born with high ( n = 14, 10.59 ± 0.43 μg/dl) or low ( n = 15, 5.09 ± 0.28 μg/dl) serum cortisol levels had similar ( p> 0.05) mean birth weight, serum glucose and γ-globulin concentrations at birth. Post-natal profiles of serum cortisol for kids of both groups declined to a similar ( p > 0.05) level by 2 days of age. The ACTH responsiveness of serum cortisol at 5 days of age was not different ( p > 0.05) between groups. The kids with higher serum cortisol levels at birth gained about 33% more weight ( p < 0.05) during the 5-day period than those with lower serum cortisol levels. Serum glucose levels after birth remained normal at all time intervals measured and were higher ( p < 0.05) for kids born with high serum cortisol levels. The peak serum γ-globulin level reached at about 18 h after the first colostrum feeding was greater in kids of `high' cortisol group, and a consistently greater level of serum γ-globulin was maintained throughout the study compared to the kids of the `low' cortisol group. The results suggest that there does not appear to be a relationship between serum cortisol levels at birth and birth weight or post-natal adrenocortical function of normal kids. High serum cortisol levels at birth are desirable for growth and immunoglobulin acquisition of neonatal kids. The possible mechanisms were discussed.