The immune response in sheep: analysis of age, sex and genetic effects on the quantitative antibody response to chicken red blood cells.

The purpose of the present work was to investigate the influence of age, sex and genetic factors on the quantitative antibody response of sheep, when environmental conditions were kept under strict control. Data provided by this experiment show that sheep of 3 months old are capable of developing a measureable response to a single intravenous injection of chicken red blood cells, but the average level of haemagglutinins produced by young lambs is significantly lower than that found in adults (2 to 5 years old) of the same sex (p less than 0.001). At 7 to 8 months of age, the antibody response observed in lambs reached the adult level. There is also a tendency for a better response in females than in males, but the observed difference is small (0.6 log2) and statistically not significant. Heritability estimates clearly indicate a genetic influence on the quantitative antibody response of sheep to chicken red blood cells.