@conference {3672, title = {BRIEF COMMUNICATION: High ultimate pH in short-scrotum male lambs processed during the breeding season}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {194-196}, address = {Rotorua}, abstract = {

Historically in New Zealand male lambs were castrated at the time of docking, however, there has been a move to instead create short-scrotum males, in which the testes are pushed within the body cavity and the scrotum removed (Johnson et al. 2007). This results in short- scrotum males, having similar physiological characteristics to entire ram lambs, except that they are almost always infertile and, therefore, do not present a management risk if they are accidently mixed with ewes or ewe lambs during the mating season. The normal ultimate pH of lamb meat is considered to be 5.50 to 5.80, with values above 5.8 and in particular above 6.0 considered high, and resulting in negative meat quality outcomes. There have been a number of studies that have investigated whether or not sex differences in the ultimate pH of lamb exist. The results are not always consistent with some studies reporting elevated ultimate pH in non-castrated male lambs (Johnson et al. 2005; Bain et al. 2009), whilst others have shown no differences (Kerslake et al. 2012; Schreurs 2013). In commercial farming operations there is a mix as to how farmers manage their lambs of different sexes during the finishing period prior to slaughter, and in many farming operations this period coincides with the on-set of the breeding season.

Given the most recent papers in this area have concluded that there is no sex-effect on ultimate pH, the purpose of this paper is to report on data collected from a trial that set out to invoke high ultimate pH (to investigate potential live-animal predictors of high ultimate pH) in short-scrotum male lambs during the breeding season.

}, issn = {1176-5283}, author = {PL Johnson and Stuart AD and Mackie A} } @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 {79005, title = {Impacts of different forages and packaging conditions on colour and lipid oxidation stability of lamb loins}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {147-149}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Fresh meat colour is one of the most important quality attributes that affects the consumer{\textquoteright}s meat purchasing decisions (Renerre \& Labas 1987). A number of factors such as feed type, animal breed, age, sex, display and packaging conditions influence the rate of metmyoglobin formation. Metmyoglobin is the pigment responsible for brown colour on meat surface during retail display ... continued}, issn = {1176-5283}, author = {Kim YHB and Stuart AD and Rosenvold K and Maclennan G} }