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ARS Home » Southeast Area » Mississippi State, Mississippi » Poultry Research » Research » Research Project #433611

Research Project: Improving Efficiency of Growth and Nutrient Utilization in Heavy Broilers Using Alternatives to Antibiotic Growth Promoters

Location: Poultry Research

2022 Annual Report

1. Evaluation of antimicrobial alternatives through dietary inclusion and in-ovo administration on growth performance and production efficiency. 1.1. Determination of the apparent metabolizable energy (AME) of antimicrobial alternatives in broiler diets with or without antibiotic growth promoters (AGP). 1.2. Evaluation of in ovo injection of antimicrobial alternatives. 1.3. Evaluation of antimicrobial alternatives on broiler gut histology and gut microbiome. 2. Effect of alternative diets on early gut development in broilers raised with and without AGP. 2.1. Determination of the AME and amino acid (AA) digestibility of alternative protein supplements used in broiler diets. 2.2. Evaluation of live performance, carcass characteristics, and gut histology of broilers when fed alternative diets with or without when challenged with a coccidiosis vaccine.

At day of hatch, male broilers will be obtained from a commercial hatchery and raised on common diets in common floor pens in an environmentally-controlled building. On d 14, broilers will be randomly allocated to 60 battery cages in groups of 10. Battery cages will be housed in two identical solid sided research rooms, with separate environmental control. For the coccidiosis vaccine challenge, on day 14, half the broilers (30 cages of 10 birds each) will be inoculated with a commercially available coccidiosis vaccine. Methods will be modified from Adedokun et al. (2016). Briefly, birds will be orally gavaged with 12x coccidial vaccine suspended in distilled water. The remaining birds (unchallenged) will receive a sham treatment via oral gavage of 0.6 mL distilled water. A live oocyst vaccine (COCCIVAC®-B52, Merck Animal Health) isolated from chickens and prepared from anticoccidial-sensitive strains of E. acervlulina, E. mivati, E. maxima, and E. Tenella will be used in this trial. On d 17, after an acclimation period, broilers will be fasted overnight to expel all non-experimental feed and then placed on experimental diets (treatments delineated below) for 72 hours. During this collection period, all feed consumed and refused will be measured in addition to total excreta output; excreta from all birds within a cage will be pooled for analysis. Upon completion of the experimental period on d 21, broilers will be transferred to four floor pens until d 35. Challenged and unchallenged birds will be kept separate between the experimental periods. On d 35, birds will be randomly allocated to battery cages in groups of 5. On d 38, after an acclimation period, broilers will be fasted overnight and begin experimental diets for 72 hours. During this collection period, all feed consumed and refused will be measured in addition to total excreta output. Additionally, upon completion of the experimental periods at 21 and 42 d, birds will be weighed to determine body weight (BW) and BW gain (BWG). During the experimental periods, lighting and temperature will be set at average commercial conditions. Temperatures will be set at 32°C from day 1 to 3, 31°C from day 4 to 6, 29°C from day 7 to 13, 27°C from day 14 to 20, 24°C from day 21 to 27, 21°C from day 28 to 34, and 18°C from day 35 to 42. Lighting will be set as following: from 0 to 7 d, light will be set at 23 light: 1 dark at 3 foot candles, from 8 to 11 d, 23L:1D at 3 foot candles, from 12 to 42 d 23L:1D, 1 foot candles.

Progress Report
An experiment was conducted to determine the effects of supplemental biochar on ileal digestible energy and live performance of broilers. Previous research has demonstrated that biochar supplementation may improve performance and nutrient digestibility in pigs and turkeys. The non-nutritive characteristics of this additive, indicate that these responses are likely related to alterations in digestive physiology, but limited research has been conducted in broilers and these effects are likely dose dependent. The results from this experiment demonstrated that biochar supplementation regardless of supplementation concentration did not affect live performance or positively affect ileal digestible energy in growing broilers. Thus, further research should be conducted to determine if the effects of biochar supplementation are more pronounced or necessary when broilers are challenged subclinical enteric infections. Also, an experiment was conducted by stakeholder request to quantify the effects of varying proportions of dietary pellets and fines on broiler growth performance and carcass yield. Improved pellet quality has been observed to improve broiler growth performance, nutrient utilization, and handling characteristics. However, conditioning and pelleting has been reported to increase the cost of diet manufacturing by 4 to 6 dollars per ton. Field evidence has suggested that pellets concentrations above or below 70 and 30%, respectively, can significantly impact broiler production costs, but limited research has determined if beneficial effects can be observed when dietary pellet concentrations fall within that range. The results from this study indicated that increasing proportions of pellets to fines concentrations did not improve the performance and yield of broilers. Therefore, a relaxed emphasis on pellet concentrations as a qualitative measure may be accepted and applied in broiler feed milling, but further research on the interactive effects of pellets concentrations and nutrient levels should be assessed to ensure that these effects are not interdependent.

1. Biochar supplementation in broiler diets. Previous research has demonstrated that biochar supplementation may improve performance and nutrient digestibility in pigs and turkeys, but has not been evaluated in broilers. An experiment was conducted to measure the effects of supplemental biochar in ileal digestible energy and live performance in broilers. Biochar showed no net benefits for digestibility or performance.

2. Feed form effects in broiler diets. Feed manufacturing is a significant cost for broiler integrators and increased focus on pellet content has resulted in increased manufacturing costs. This research shows that reduced pellet content does not affect live performance and carcass yield. Feed manufacturing costs can be reduced through relaxed milling process standards.

Review Publications
Mccafferty, K.W., Morgan, N., Cowieson, A., Choct, M., Moss, A. 2022. Varying apparent metabolizable energy concentrations and protease supplementation affected broiler performance and jejunal and ileal digestibility from 1 to 35 d of age. Poultry Science. 101:101911.
Mccafferty, K.W., Choct, M., Musigwa, S., Morgan, N., Cowieson, A., Moss, A. 2022. Protease supplementation reduced the heat increment of feed and improved energy and nitrogen partitioning in broilers fed maize-based diets with supplemental phytase and xylanase. Animal Nutrition. 10:2022, 19-25.