Abstract

A sheep breeding experiment at Woodlands Research Station consists of 5 self-contained Romney selection lines (closed in 1973). Four lines are selected respectively for dam's number of lambs born (dam NLB), 100-day weight, hogget fleece weight, and a production index in which all 3 traits are combined, while the fifth line is a randomly selected control. Back fat thickness was measured in the 1982 born ewe lamb progeny at approximately 8 and 14 months of age. Relative to the controls (back fat 6.3 mm) the dam NLB (5.0 mm) and the production index (4.8) lines had 20% lower back fat depths (P<0.01) in May after variance adjustment for live-weight. The differences were slightly lower when measured in November. The fat thickness of the 100-day weight and hogget fleece weight line progeny were similar to the controls. The heritability of back fat depth adjusted for live weight by half-sib analysis was 0.28

JN, Clarke, GL Bennett, and AH Kirton

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 239-242, 1984