Response of Broilers to Dietary Inclusions of Sugarcane Bagasse and Protease in a Reduced Crude Protein Diet
Published:January 10, 2023
By:N.K. SHARMA 1, S. K. KHERAVII 1, K. GURNEY 2, M. CHOCT 1 and S.-B. WU 1 / 1 School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; 2 Redsun Nutrition Pty Ltd, Munruben QLD 4125, Australia.
Nutritional strategies to improve performance of broilers offered reduced crude protein (RCP) diets supplemented with crystalline amino acids are of interest to the poultry industry. We hypothesized that the dietary inclusion of moderate amounts of insoluble fibre would stimulate gizzard function and increase the retention time of digesta in the foregut allowing more time for exogenous protease to act on their substrates leading to greater digestibility of protein/amino acids and better performance of birds offered RCP diets. This study investigated the effectiveness of dietary sugarcane bagasse as an insoluble fibre source with or without an exogenous protease in RCP diets fed to broilers.
A total of 672 d-old Ross 308 male parent-line birds were fed a common starter diet until 10 d of age. On d 10, birds were assigned to 8 treatments, each replicated 6 times with 14 birds per pen in a 2 × 2 × 2 factorial arrangement of treatments with dietary crude protein (CP)- normal (NCP, 213 g/kg CP for 10 to 24 d in grower phase and 195 g/kg CP for 24 to 35 d in finisher phase) or reduced by 25 g/kg CP in both the grower and finisher phases, bagasse included in the diets at 0 or 20 g/kg and protease added over the top of the diets at 0 or 0.2 g/kg. The diets were cold-pelleted and contained wheat, sorghum and soybean meal as major ingredients. All diets were supplemented with xylanase and phytase and were formulated to meet Ross 308 nutrient specifications. Feed intake, weight gain, and FCR were determined from d 10 to 35. Carcass parameters were measured on d 35 and 42. JMP Pro 14 was used to perform analyses of variance and significance was determined at P < 0.05 using Tukey’s HSD test.
The reduction in dietary CP decreased feed intake (P < 0.001) by 3.66% (3361 versus 3238 g), weight gain (P < 0.001) by 5.78% (2284 versus 2152 g) and increased FCR (P < 0.001) by 3.2 points (1.476 versus 1.508) during d 10 to 35. Protease or bagasse had no effect (P > 0.05) on feed intake during the experimental periods. A 3-way CP × bagasse × protease interaction was observed for weight gain during d 10 to 24 (P < 0.05) and for FCR during d 10 to 24 and d 10 to 35 (P < 0.01). During d 10 to 24, weight gain was increased by 4.37% (1030 versus 1075 g) when protease was added to the NCP diet without bagasse but not when it was added to the RCP diet without bagasse. Meanwhile, FCR was decreased by protease in all except when bagasse was added to the NCP diet. On the other hand, dietary inclusion of bagasse only reduced FCR when no protease was added in the NCP diet (1.354 versus 1.327 during d 10 to 24 and 1.476 versus 1.459 during d 10 to 35) but not in any other circumstance. There were no further improvements in weight gain and FCR when bagasse and protease were added in tandem in the NCP diet. Bagasse increased (P < 0.01) relative gizzard weight by 8.47% on d 35 and 9.52% on d 42. Reduction in CP decreased (P < 0.01) relative pancreas weight by 14.01% and tended to decrease (P = 0.057) breast meat yield (181 versus 176 g/kg) on d 42. A 3-way CP × bagasse × protease interaction (P < 0.01) was observed for the relative abdominal fat pad weight on d 42. The relative abdominal fat pad weight decreased when protease or bagasse alone was added to the NCP diet but increased when added to the RCP diet (P < 0.01). No changes were observed when they were added in tandem.
This study showed that dietary supplementation of bagasse or protease alone improved performance of broilers offered a NCP diet. There were no further improvements on performance when they were added in tandem. The addition of protease alone in the RCP diet improved FCR. The RCP diet in this study may have been marginal in some other amino acids, possibly glycine which led to the lack of response of bagasse addition in the RCP treatment.
ACKNOWLEDGEMENTS: This research was funded by the AgriFutures Australia.
Presented at the 32th Annual Australian Poultry Science Symposium 2021. For information on the next edition, click here.
1. The main factor that needs to be considered in the maintenance of poultry is the health management of the digestive tract.
2. The health of the digestive tract in chickens is very important to ensure their health and productivity.
3. Several factors that can affect the health of the digestive tract in chickens are feed, cage management, sanitation, and the environment.
4. Out of all the above factors nutrition / feed plays a very important role in maintaining gut health.
5. Gut health management has gained even more interest in last few years in poultry production due to increasing demands for economic efficiency, animal welfare, food safety, reduction in environmental impacts, and a ban on or avoidance of antibiotic growth promoters (AGPs) use (Morgan, 2017).
6. The common aspects affecting bird gut health are stress, exogenous infection, diet and water, etc.
7. Let us discuss about Protease enzyme.
Proteases:
8. Protease is an important factor in protein digestion as it hydrolyses the less digestible proteins in animal feeds and breaks them down into more usable peptides.
9. Improving dietary protein digestibility with a specific protease inclusion can reduce feed cost by allowing the use of lower crude protein feedstuffs with lesser quality amino acids, effectively lowering protein and digestible amino acids levels required from the feedstuffs up to 10%.
10. Unconventional protein sources, such as Rapeseed meal (RSM), sunflower cake, Guar meal, cotton seed meal (CSM) and Corn Distillers Dried Grains with Solubles (DDGS) etc due to nutrient variability can lower quality protein levels and reduce digestibility in poultry.
11. Supplementing exogenous protease enables poultry that lack adequate levels of endogenous enzymes to digest proteins in the diet, which reduces the flow of undigested protein and other anti-nutritional entering the large intestine.
12. Anti-nutritional factors impair smooth digestion such that significant quantities of undigested starch and/or protein enter the large intestine, stimulating the activity of putrefactive bacteria and pre-disposing the animal to intestinal disorders.
13. As already evident from the studies, the supplementation of exogenous enzymes will improve small intestine digestion and as a result limit substrate availability in the hindgut, therefore mitigating any potential GIT microbial dysfunction.
14. There is enormous scope to explore the effect of supplementation of enzyme combinations targeting feed composition on gut health and ultimately impacting growth and efficiency.
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