Relationship Between Dietary Protein Source (Soybean Meal vs. Canola Meal) and Meat Quality Traits in Feedlot-Fattened Indigenous Dairy Lambs

Although soybean meal (SBM) is generally used as the main protein source in livestock diets, canola meal (CM) appears as a sustainable alternative, since it lowers diet cost, especially when regionally produced, while still meeting animal nutritional needs. The objective of this study was therefore to assess the effects of dietary protein source (SBM vs. CM) on carcass traits and meat quality characteristics of feedlot-fattened dairy lambs. A total of 193 weaned lambs, approximately 3 months of age, from two indigenous Greek dairy breeds (75 Chios and 118 Serres), were used. Lambs were randomly assigned to one of two isocaloric and isonitrogenous dietary treatments: a control ration containing SBM as the primary protein source, and an alternative ration in which SBM was completely replaced by CM. After a fattening period of 13 weeks for Chios lambs and 15 weeks for Serres lambs, animals were slaughtered upon reaching a live weight of 35–40 kg, and hot and cold carcass weights were recorded. After 24 h of carcass storage at 4 °C, Longissimus lumborum muscle was sampled and used for the measurement of pH, colour attributes, cooking loss, shear force, and intramuscular fat content. Lipid oxidation was evaluated on days 1, 3, 6, and 9 of refrigerated storage at 4 °C. The substitution of SBM by CM as the main dietary protein source did not affect carcass traits in Serres lambs, whereas CM- treated Chios lambs showed an increased hot and cold carcass weight (p < 0.05). Meat quality characteristics were not affected by the dietary treatment in either Chios or Serres lambs, with the exception of meat oxidative stability that was deteriorated in CM compared to SBM Serres lambs (p < 0.001). In conclusion, the utilization of canola instead of soybean meal did not negatively influence carcass traits or meat quality characteristics in either Chios or Serres lambs, with the exception of lipid oxidation which was significantly higher in CM supplemented Serres lambs.