Graham Gardner

In this studies a prototype low cost portable handheld microwave system (MiS) designed and tested for back fat depth measurements using non-invasive techniques on lamb carcase in commercial abattoirs. For this application, two different type antennas was designed and tested. These results demonstrate the capacity of this prototype MiS system together with proposed antennas to estimate fat depth at the C site in lamb carcasses non-invasively in commercial abattoir at rate 100 carcase in 30 minutes.

The USA and China are Australia’ s strongest sheep meat export markets , however insights into consumer perceptions of Australian sheep meat are limited . IMF and shear force are good indicators of eating quality for Australian consumers however the relationship for American and Chinese consumers is unknown. Eating quality scores (tenderness, juiciness, liking of flavour, and overall liking) were obtained from American, Australian, and Chinese consumers for Longissimus lumborum and semimembranosus muscles collected from Australian sheep (n=328). Shear force was negatively associated with all sensory traits, consistent for all countries. Whereas, increasing IMF levels had a positive impact on all eating quality scores for all countries, however the most significant change was observed for Australian consumers indicating their higher sensitivity towards IMF differences.

This study tested the palatability of lamb meat derived from pasture versus grain finishing systems. The loin and topside muscles from 105 lambs were collected. Sensory scores were generated using untrained consumers who tasted 5 day aged grilled steaks, scoring tenderness, juiciness, flavour and overall liking. Consumer scores did not differ in female lambs fed grain or pasture diets. However in wether lambs palatability scores for overall liking, tenderness and juiciness were higher for those on grain compared to those on pasture. Correcting for intramuscular fat accounted for most of these differences. These results confirm that Australian consumers do prefer grain-fed lamb meat, but only in wether lambs.

Brown discolouration of lamb meat on retail display reduces consumer appeal, limiting the shelflife and value of the product. The rate of change in colour from red to brown, known as colour stability, is increased in short aged meat with high intramuscular fat (IMF) content (Calnan et al 2014). Therefore genotypic selection for IMF to improve sensory appeal may reduce lamb meat colour stability. Extended aging of lamb meat also reduces colour stability of lamb meat (Jose et al, 2008), a concern for chilled meat shipped for 35 - 70 days to distant markets. High intramuscular vitamin E (a-tocopherol) concentration, achieved by dietary supplementation, slows the loss of redness in lamb aged 5 - I 0 days (Jose et al, 2008). Given that colour stability worsens with aging, the impact of a-tocopherol may be greater in long-aged and high IMF meat. We hypothesised that high muscle a-tocopherol concentration in lambs will retain redness during display of the longissimus, particularly in long-aged and high IMF meat.

Ewes that lose less weight when there is a shortage of paddock feed are potentially more profitable because they require less supplementary feeding or can be grazed at higher stocking rates during autumn/winter (Young et al. 2011). Adams et al. (2006) have shown that sheep genotypes which lose more weight when underfed have lower metabolic reserves including fat. This paper tested the hypothesis that selection for increased fatness would reduce the rate of liveweight loss in adult Merino ewes when nutrition was restricted.

Lean meat yield is a key efficiency and profit driver throughout the supply chain. Lamb is sold in lower yielding formats at a retail level (ie more bone and fat) compared to beef, pork and chicken and is typically more expensive, especially when compared on a $/kg lean at retail (Pethick, Ball et al. 2010). High yielding carcases deliver cuts that have a better shape and ensure retailers do not have to present products of overly fat animals for display and sale. For processors a high yielding animal represents increased efficiency in the boning room. These carcases require less labour to trim fat and there is less carcase wastage. For producers, higher yielding animals can be finished to heavier weights without becoming overly fat and accruing penalties. Additionally, fast growing, high yielding animals can be finished either faster or to heavier weights, in a shorter period of time, offering the producer savings on feed costs. The challenge is to produce a fast growing lamb that can be turned off quickly, that are of favourable conformation, and also gives a satisfactory return to the producer. It is increasingly important that price signals reflect not just more carcase as it may represent increasing amounts of fat. With continued evolution of the payment scheme of lamb there is the potential to improve profitability through the use of genetic selection for increased yield.

The brown discolouration of lamb meat reduces its appeal to consumers, costing the Australian Lamb industry considerably due to the discounting of product. Lamb meat browning is caused by the oxidisation of myoglobin pigments into the brown metmyoglobin form. The rate of this oxidisation is greater in more aerobic muscles (O'Keeffe and Hood 1982), with aerobicity quantified by the measurement of isocitrate dehydrogenase activity (ICDH). High intramuscular fat percentages (IMF) have been associated with high ICDH levels, so if industry moves to increase IMF we can hypothesise that there will be an ICDH linked increase in the brownness of lamb meat after 3 days of retail display..