Analysis of Frieswal cattle for survival pattern, herd structure and expected herd life

Abstract

Records of 1 024 Frieswal cows maintained at Military Dairy Farm, Meerut, during 1987–2007 were used to study
the lactation specific survival pattern, herd structure, expected herd life and overall life time statistics. Study revealed
that 76% of the total cows at first lactation were survived for next lactation and vis-à-vis 24% cows left the herd after
completion of first lactation. The probability of a cow to survive in the herd decreased along with the lactation number.
Herd structure showed that about 37% of the herd comprised first calvers and about 80% of the total females present in
the herd belonged to first 3 lactations only. The expected herd life at first lactation was 2.05 lactations more and follows
a decreasing trend along with the increase in lactation. Average net reproductive rate was 0.86, which indicated that
each cow produced less than one female calf. It was observed that the proportion of cows being lost from the herd was
0.24 in first lactation. This is the equilibrium replacement rate required to maintain the herd size.