Path analysis of lifetime milk yield in Sahiwal cattle

The path analysis for life time milk yield revealed that longevity (63.3%) was the most important contributing factor, followed by number of lactations (36.1%), first lactation milk yield (25.88%), first lactation length (16.97%) and first calving interval (5.3%). Age at first calving contributed practically nil. Longevity mainly contributed by its direct effect (40.26%), whereas number of lactations other than its direct effect (7.76%) contributed through longevity (7.49%). The first lactation milk yield had contributed mainly by its direct effect (12.92%). The first lactation length mostly contributed through the first lactation milk yield (10.25%). First calving interval influenced the lifetime milk yield through longevity (2.77%) and number of lactations (1.46%) other than its direct effect (1.47%). The model explained 77 per cent of the total variation of lifetime milk yield by these causal factors.