Nutrition and LMY Research Project

Summary

Project title: Nutrition & LMY Project - The effects of ewe gestational condition, genetic potential for lean meat yield and finishing nutrition on the body composition, lean meat yield and meat quality of male second cross prime lambs.
The prime lamb industry is seeking to increase lean meat yield (LMY) whilst maintaining meat eating quality. This project investigated the impact of gestational condition score, sire breeding values for LMY and finishing diet on the body composition, lean meat yield and eating quality of prime lambs. Adult maternal ewes were artificially inseminated to 9 sires selected on research breeding values for high, medium and low LMY. Subsequently, 648 pregnant ewes were randomly allocated and managed towards three different condition score (CS) targets of 2.5, 3.0 and 3.5 at lambing. Ewes at lambing were different by an average of 0.7 CS and 13kg liveweight between the CS2.5 and CS3.5 treatments. There were very few significant interactions between CS treatment, finishing diet and sire group. The CS 2.5 treatment resulted in lower birth, marking, weaning, finishing, pre-slaughter and carcass weight in multiple lambs. These lambs were also chemically leaner (by approximately 1% unit) than lambs born to CS 3.0 and CS 3.5 treatments. The difference in fatness appeared to be due to differences inter-muscular fat (and possibly intra-muscular fat). However, there were no significant differences in lean meat yield measured by either partial or full bone out.  The finishing diet affected growth rate, food conversion ratio and pre-slaughter weight but not leanness or fatness.  Progeny from high LMY sires were leaner, with less subcutaneous and intramuscular fat and had a high shear force.  The results indicate producers will gain more from improved CS management for lamb survival and weight benefits and this may also result in improvements in fresh and retail meat colour.