Genetic analysis of milk production traits in Jonica goats

Data from 1009 lactation of 220 Jonica goats, collected over a 5-year period were used to study the effect of different environmental factors on milk production traits and to estimate the heritability for these traits. The considered lactation traits were: milk yield, fat and protein yielded and lactation length. Year of kidding, parity and type of birth were all important sources of variation for milk production traits. In particular, the year of kidding affected all the considered traits; the parity of does influenced milk yield and lactation length, and the type of birth was a significant source of variation only for milk yield. Estimates of heritability obtained in the present study were 0.22, 0.17, 0.25, 0.23 for milk yield, lactation length, fat and protein yielded, respectively. The results obtained in Jonica breed suggest that genetic variability in milk production traits is adequate for selection indicating a good possibility of improvements in Jonica goat population by adopting judicious selection strategies.