Factors affecting performance of Nili-Ravi buffaloes in Pakistan.

Effects of herd, year, age, season, and lactation length on milk yield and reproductive efficiency for the Nili-Ravi breed of buffalo were determined by analysis of variance of 5,716 lactation records from two herds in Pakistan. Herds differed in all traits. Herd average milk yields were 1,702 and 2,064 kg. Year, season, herd, parity number, days in milk, days open, age, and sire all influenced milk yield. Herd, year, season, and parity number also had significant effects on days open and calving interval. Month of calving was important for time until return to estrus. Percentages of variance in milk yield attributed to herd, year, sire, cow, and residual were 20.3, 11.4, 4.3, 17.0, and 47.0. Classification of lactation length (greater than 60, greater than 250, or at least 305 days) markedly influenced the sire component of variance suggesting some interdependence of milk yield and lactation length. Total variance for milk yield was 466,911 kg2. Within herd heritability for milk yield was .25, and repeatability was low (.31). Predicted breeding values for sires for 250 to 305-day milk ranged from -172 kg to +260. Cows in Herd 1 completed 5.58 lactations with an average herd life of 12.3 yr; Herd 2 cows completed 4.52 lactations with culling at 10.6 yr. Frequency of termination of lactations because of mastitis, reproductive problems, or health was similar to frequencies for cattle. Factors affecting milk yield in buffaloes are similar to those of cattle.