Genetic variation in intramuscular fat of prime lamb supplemented with varying concentrations of degummed crude canola oil
Flakemore, AR and Balogun, RO and McEvoy, PD and Malau-Aduli, BS and Nichols, P and Malau-Aduli, AEO, Genetic variation in intramuscular fat of prime lamb supplemented with varying concentrations of degummed crude canola oil, International Journal of Nutrition and Food Sciences, 3, (3) pp. 203-209. ISSN 2327-2694 (2014) [Refereed Article]
The main objective of this study was to quantify the intramuscular fat (IMF) content of Longissimus thoracis et lumborum, biceps femoris and triceps brachii muscles in genetically divergent lambs supplemented with varying levels of degummed crude canola oil (DCCO). Over a nine-week feeding trial, twenty-four first-cross prime lamb progeny from Merino, Dorset and White Suffolk rams mated with purebred Merino ewes under the same nutritional management were supplemented with one of three levels of wheat-based pellets with or without DCCO. The experimental treatments included the Control (1kg of plain wheat-based pellets without DCCO/head/day on dry matter basis), High (1kg of wheat-based pellets containing 50ml of DCCO/kg/head/day on dry matter basis) and Medium (500g of Control + 500g of High wheat-based pellets/head/day on dry matter basis). All lambs had a three-week adjustment period and had ad libitum access to lucerne hay and water. After nine weeks of supplementation, all experimental lambs were slaughtered at a commercial abattoir with the exception of four purebred Merino ewes retained in the flock for breeding purposes. IMF content was analysied in the Longissimus thoracis et lumborum, biceps femoris and triceps brachii muscles using a chloroform/methanol extraction @ 2:1 vol/vol ration and precipitated with a 0.25 volume of 10% potassium chloride solution. IMF content varied significantly with the level of DCCO supplementation (P<0.0125) and muscle type (p<0.0001). There were also significant interactions between sire breed and level of DCCO supplementation (P<0.0016), and muscle type and sex (P<0.0003) in IMF content. Prime lambs in the Control and Medium level of DCCO supplementation had the most IMF (3.18±0.12 and 3.28±0.14% respectively) and the High treatment had the least 2.96±0.10%), suggesting a decrease in IMF as supplementation levels with DCCO increased. Among muscle types, the Longissimus thoracis et lumborum had more IMF (3.69±0.11%) than the biceps femoris (2.87±0.11%) and triceps brachii (2.90±0.12%). It was also evident that in ewes, the biceps femoris had the least IMF (2.4%) compared with Longissimus thoracis et lumborum (3.6%). This result indicates that the supplementation of prime lambs with DCCO can be used as a management tool to vary the levels of IMF content to suit different market specifications dictated by meat consumers. Whereas in themselves, sex and sire breed of lambs used in this study were not the primary drivers of IMF deposition, our results demonstrate that sheep farmers can modify their nutritional management and breed combinations by effectively utilizing appropriate sire breed and supplementation level combinations to manipulate the IMF content of various muscle types in ewe and wether prime lambs.