CIRCULATORY INSULIN LIKE GROWTH FACTOR-I (IGF-I) CONCENTRATION IN DICTATING COWS

摘要

To investigate the circulatory levels of IGF-I in lactating crossbred cows a total of 37 blood samples were collected from the jugular vein at 8.30 AM before offering feed. Simultaneously milk samples were also collected on the day of blood collection. The radioimmuno assay of IGF-I was standardized and the plasma levels of IGF-I were measured. The samples were grouped based on stages of lactation at 60 day intervals on milk production basis i. e., upto 5kg and above 5to 10 kg and with increasing number of lactation i. e., I, II, III., IV & V and above. The IGF -I levels varied during different stages of lactation (P< 0.01) along with milk yield (P<0.01). The IGF-I levels also varied (P<0.05 ) during different parity, however, there was no correlation between milk yield and IGF -I concentrations during different parity and stages of lactation. IGF-I levels were higher (P<0.01) in animal producing milk yield between 6 -10 kg as compared to low producers (1-5 kg),and were positively correlated with milk yield (P<0.05).