No abstract

Non-conventional feed ingredients are receiving more interest in their ability to increase farming efficiency, sustainability and animal performance. The objective of this study was to determine the optimal rate of inclusion level of the full-fat black soldier fly larvae (BSFL) in broiler diets and to evaluate their impact on performance, nutrient digestibility, and the immune system (blood cells and intraepithelial lymphocytes). A total of 400 male day-old Ross 308 broilers were randomly assigned to 5 treatment groups with 8 replicates each. Five inclusion levels of full-fat BSFL were investigated across starter (0, 2.5%, 5%, 7.5% and 10%), grower and finisher diets (0, 5%, 10%, 15% and 20%). All diets were formulated based on digestible amino acid values according to the Aviagen (2016) recommendations. A polynomial regression at different degrees was performed to analyse broiler performance parameters (body weight, body weight gain, feed intake, and feed conversion ratio), nutrient digestibility, and blood cell count. Intraepithelial lymphocyte population data was analysed performing univariate linear regression. During the entire experimental period (from 2 to 42 d), BSFL inclusion levels decreased the feed conversion ratio by 10% in broilers that received 20% BSFL in their diets ( P < 0.05). Lymphocytes and white blood cell count decreased linearly by 47.7% and 35.9%, respectively, with up to 20% BSFL inclusion ( P < 0.001) . A 4-fold decrease in CD3+ T lymphocytes and a 9.7-fold decrease of CD3+CD8+ intestinal cytotoxic T lymphocytes occurred in broilers fed 20% BSFL compared to the control group. These findings suggest that the inclusion of BSFL can improve broiler performance and potentially reduce immune response energy expenditure in birds fed 20% BSFL for 42 d.

Reducing dietary CP can reduce N pollution. Much research has been reported in corn-based diets; however, the amino acid ( AA ) profiles of wheat-based diets differ. Poor performance as a result of reduced protein ( RP ) has been overcome in corn-based diets with essential AA and glycine ( Gly ) supplementation. The current study examined RP levels and Gly in wheat-based diets. An industry standard protein ( SP ) diet plus 3 RP diets with and without Gly supplementation, to match the SP treatment at 0.713 and 0.648% digestible Gly for the grower and finisher periods respectively, were fed to male broilers from day 10 of age. Grower CP included 22.5, 20.6, 18.3, and 17.7% (days 10–21) and finisher CP included 19.7, 17.8, 16.2, and 15.5% (days 21–35). Performance, meat yield, N efficiency, water intake, and apparent ileal digestibility of N and AA were measured. No difference in body weight gain ( BWG ), feed intake, or feed conversion ratio ( FCR ) were observed at 20% CP compared to the SP treatment. However, further reducing protein reduced BWG ( P < 0.001), feed intake ( P < 0.001), and increased FCR ( P < 0.001). Supplementation of 0.713% Gly in the grower period increased BWG ( P < 0.001) and reduced FCR ( P < 0.001). Relative meat yield was not affected by dietary protein, however reducing CP increased relative fat pad weight ( P < 0.001). Nitrogen efficiency increased with decreased CP in both grower (R 2 = 0.69) and finisher (R 2 = 0.80) treatments. Water intake decreased (R 2 = 0.83) with decreasing CP intake. Apparent ileal digestibility of AA and N were higher in RP diets ( P < 0.05). The benefits of reduced water intake and increased N efficiency and the disadvantages of poor performance and increased body fat in RP corn-based diets have been identified in RP wheat-based diets. Furthermore, at 18.5% CP the supplementation of crystalline AA and Gly can maintain BWG and FCR observed in SP diets.