Observed and predicted first lactation milk yield in Surti buffaloes

Abstract

305FLMY was predicted from fortnightly, monthly and bimonthly test day milk yields using 2 sampling schemes (systematic and stratified random sampling) in Surti buffaloes maintained at Network Project on Surti buffaloes, Livestock Research Station, Vallabhnagar. The observed 305 days and total first lactation milk yield were 1,116.97 ± 13.49 and 1,155.16 ± 10.93 kg respectively. The predicted 305 days milk yield was higher than observed 305 days milk yield and showed increasing trend with increasing test day interval in both the sampling schemes. The effect of sire and season of calving was found to be highly significant on observed and predicted 305 days first lactation milk yield based on systematic and stratified sampling schemes with fortnightly, monthly and bimonthly sampling intervals. The heritability estimates for OMY305 and OMYT was high at 0.639 ± 0.181 and 0.669 ± 0.184 respectively. Similarly, the heritability estimates for predicted 305 days first lactation milk yield based on systematic sampling scheme with the interval of fortnightly, monthly and bimonthly were 0.584 ± 0.176, 0.587 ± 0.176 and 0.549 ± 0.172 respectively. The respective estimates based on stratified sampling scheme were 0.582 ± 0.175, 0.601 ± 0.177 and 0.378 ± 0.152. The genetic and phenotypic correlation coefficients of predicted milk yield based on both systematic and stratified random sampling schemes with OMY305 and OMYT were also positive, high and approaching to one. All the 5 measures, viz. average error, per cent average error, average absolute error, per cent average absolute error and variance of error under fortnightly interval were lower than monthly and bimonthly intervals in both the sampling schemes. The above measures of error were slightly lower for systematic sampling scheme as compared to stratified random sampling scheme. Keeping the cost and difficulty in data recording, both systematic and stratified random sampling with monthly interval can be used to predict 305 days first lactation milk yield with fairly accuracy.