Lactation length in Venezuelan dual-purpose cows

Short lactations are frequently excluded from the analyses of milk records of tropical cattle. The practice leads to overestimates of milk yield and lactation length and decreases the accuracy of selection procedures. The objectives of this paper are to quantify lactation length using unselected records from a sample of Venezuelan dual-purpose cows, evaluate some of the sources of variation and discuss suitable editing procedures for milk production records in these populations.