@conference {3672, title = {Intramuscular fat content of New Zealand lamb M. longissimus lumborum}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {189-193}, address = {Rotorua}, abstract = {

The content of intramuscular fat (IMF\%) in lamb is an important trait for the lamb-meat value chain. Not only is IMF\% an import-ant energy reserve for replacement stock, IMF\% is an important driver of lamb-meat eating quality. A growing body of research shows an antagonistic relationship between muscle growth traits and fat content across the lamb carcass (including IMF\%). The New Zealand sheep industry has selected for muscle growth traits for decades to improve production efficiency and reduce extremes of carcass fatness historically observed, but the impacts on IMF\% levels in New Zealand lamb have not been widely investigated.

This paper aims to stimulate discussion on lamb IMF\% by reporting on levels of IMF\% observed in the M. longissimus lumborum (LL) of 1,705 progeny test lambs raised under extensive, pasture-based production systems across New Zealand, and investigates the relationship between IMF\% and carcass weight, VIAscan{\textregistered}-predicted GR (VSGR) and lean-meat-yield percentage (VSYLD).

The average IMF\% was 2.69\%, (SD = 0.83\%, and ranged between 0.91-6.42\%). IMF\% is positively correlated with carcass weight and VSGR and negatively correlated with VSYLD. Considerable variation exists in lamb IMF\%, highlighting the opportunity to manage IMF\% through genetic improvement and optimised on-farm management.

}, issn = {1176-5283}, author = {Craigie CR and Agnew MP and Stuart AD and Shorten PR and Reis MM and Taukiri KR and PL Johnson} } @conference {69502, title = {Crossing Angus cattle with Limousin as a method of increasing meat yield}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {189-193}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {The myostatin mutation in Limousin cattle affects both dressing percent and meat yield, without a negative impact on calving difficulty. A trial was designed to introgress this mutation into Angus cattle, using double-copy Limousin bulls to produce F1 Limousin x Angus. Crossing the F1 individuals would produce F2 individuals with a quarter carrying two copies of the mutation. A pure-bred Angus herd was maintained as a Control, for breed and genotype comparisons. A total of 269 F1, 34 F2 and 129 Angus calves were born in the first four years of this trial, before a lack of funding led to early closure. A total of 112 surplus bulls were slaughtered, and measurements taken over three years, including a {\textquotedblleft}butchers{\textquoteright} dissection{\textquotedblright} into saleable meat, fat and bone of one hind-quarter per animal. Limousin crosses were 9\% heavier as yearlings, 7\% heavier at slaughter and had 2.3\% higher dressing percent (55.3\% vs. 53.0\%) than Angus. Hindquarters from Limousin crosses were 14\% heavier than from Angus, and their meat yields were greater by 1.8\% (77.0\% vs.75.2\%), due mainly to breed differences in bone weight. Overall, the Limousin-cross advantage was 6.5 kg (17\%) of saleable meat per hind-quarter, with most of the extra meat in high-value cuts.}, issn = {1176-5283}, author = {Cullen NG and Morris CA and Taukiri KR and Hill SW} }