Effects of Raw and Fermented Rapeseed Cake on Growth Performance, Methane Production, and Breast Meat Fatty Acid Composition in Broiler Chickens

SIMPLE SUMMARY: The addition of raw rapeseed cake (RRC) to broiler feed may avoid the negative effects of soybean meal (SBM), including its genetically modified origin, environmental impact, and nonprospective flexible price. Processing RRC through fermentation has also been shown to be beneficial: adding fermented rapeseed cake (FRC) to the broiler diet is a nutritional approach that addresses both the environmental issue of broiler enteric methane emission and the economic issues of soybean meal. The aim of this study was to assess the effects of partial replacement of soybean meal by a 15% addition of RRC or FRC to the diets of broiler chickens on methane emission, nitrogen retention, ether extract digestibility, growth performance, and breast muscle fatty acid composition. The FRC did not show any unfavorable effects on growth performance or nutrient utilization, and it improved the fatty acid profile of the breast muscle; additionally, both methanogens and methane emission from the fermentation of cecal contents were significantly limited. In conclusion, FRC as a partial substituent may be a valuable alternative to soybean meal in broiler chicken nutrition. ABSTRACT: The study was conducted to evaluate the effects of partial replacement of soybean meal (SBM) by 15% raw or fermented rapeseed cake (RRC or FRC) to broilers’ diets on growth performance, nutrient utilization, methane emission, and breast muscle fatty acid (FA) composition. A total of 420 one-day-old female Ros 308 broilers were used in three independent experiments (300 birds in the first experiment and 60 in the second and third experiments). In each trial, three treatments were set up: a control group (without rapeseed), and diets replaced soybean meal with 15% addition of RRC or FRC. Birds fed the FRC diet experienced no effect (p > 0.05) on performance or nutrients utilization. Methane emission and total methanogen population in the ceca was decreased (p < 0.05) with the FRC diet. The concentrations of n-3 and n-6 FAs in the breast tissue of fourteen-day-old birds were not affected (p > 0.05) by FRC. However, the n-6/n-3 ratio in the breast muscle of 28-day-old birds was reduced (p < 0.001). In conclusion, the replacement of SBM by FRC in the broiler diets did not show any unfavorable effects on performance or nutrient utilization. Furthermore, the breast meat FA profile was improved, methanogen counts significantly decreased, and methane emission was limited.