Factors affecting first lactation performance of Sahiwal cattle in Pakistan

Abstract

To study the environmental and genetic factors affecting productive and reproductive traits, data on 5,897 cows from five main recorded herds (for 1964-2004) of Sahiwal cattle in Pakistan were used. A general linear model was applied on the data. The 305-day milk yield, total milk yield, lactation length, age at first calving, dry period, calving interval and service period averaged 1,393 ± 12 kg, 1,429 ± 11 kg, 235 ± 2, 1,390 ± 4, 244 ± 3, 464 ± 3 and 1,78 ± 3 days, respectively. The age at first calving was effected by herd, year and season of birth. The 305-day and total milk yields were affected by herd, year, season of calving, age at first calving, service period and lactation length while all other first lactation traits were affected by herd, year, season of calving and 305-day milk yield. Animal model heritability estimates for these traits were 0.11 ± 0.029, 0.11 ± 0.028, 0.09 ± 0.027, 0.02 ± 0.019, 0.05 ± 0.019, 0.12 ± 0.027 and 0.04 ± 0.020, respectively. Rate of decline in first lactation milk yield was 7 l per year over the last 35 years with genetic trend close to zero. Lactation length and service period decreased and age at first calving increased by 2, 1 and 6 days per year, respectively. Herd differences for most of the traits were significant. Improved feeding and management may improve performance traits of Sahiwal cattle. Accurate recording of pedigrees and performance traits would help improve genetic parameters. Variation among animals suggested that genetic improvement in milk yield is possible in Sahiwal cattle.