The effect of different dietary levels of rapeseed meal on growth performance, carcass traits, and meat quality in turkeys

The objective of this study was to determine the effect of different dietary levels of low-glucosinolate rapeseed meal (RSM) on growth performance, blood thyroid hormone concentration, carcass traits, and chemical composition, physicochemical properties, and fatty acid profile of breast meat in growing turkeys. The experiment lasted for 21 wk. Large White BIG-6 turkeys were fed isoenergetic and isonitrogenous diets containing 0, 60, 120, and 180 g/kg of RSM. Each experimental group was comprised of 7 replicates/pen of 28 birds each. There was no effect of graded levels of RSM on final BW. An increase in the inclusion rate of RSM was followed by a linear increase in feed conversion ratio, which was significantly higher (P < 0.05) in the group fed 180 g/kg of RSM. The blood levels of free triiodothyronine decreased significantly (P < 0.05) regardless of the dietary level of RSM. No significant changes in the carcass dressing percentage or the meat fat content were observed. Significant differences were found in the fatty acid composition and physicochemical properties of breast meat. The concentrations of margaroleic acid and saturated fatty acids, including myristic and palmitic acid, in meat from male turkeys fed 120 and 180 g/kg of RSM decreased linearly; whereas the levels of oleic acid and polyunsaturated fatty acids, including linoleic and linolenic acid (an n-3 fatty acid), increased linearly. An increase in RSM content of the diets was accompanied by the unfavorable changes in selected functional properties of meat, including a significant increase in drip loss in groups fed 120 g/kg of RSM (from 1.85 to 2.38%) and 180 g/kg of RSM (from 1.85 to 3.02%) and a decrease in Warner-Bratzler shear force values in turkeys fed 180 g/kg of RSM (from 19.1 to 15.8 N). The results suggest that the quality of turkey meat could be affected by impaired triiodothyronine secretion caused by dietary RSM.