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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

2020 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
Research to demonstrate possible migration and deposition sites of in ovo-injected bioluminescent bacteria within the chicken embryo was completed and indicated that eggs injected into the amnion had significantly high numbers of E. coli cells in all tissues compared to air cell injected and control treatments 2 h post-injection (P < 0.0001). E. coli was also found on the lungs, spleen, and bursa of eggs injected either in the amnion or air cell (P < 0.05). Results indicated that in ovo injection into the amnion was more efficient than air cell injection, yielding a higher bacterial concentration in the evaluated tissues, specifically the ileum and ceca. Research to determine the impacts of the injection of probiotic bacteria individually or combined into fertile broiler hatching eggs on hatch and live performance characteristics showed no impact on hatchability, body weight gain, or mortality of injected embryos, but injections affected gastrointestinal tissue length, weight, and pH. This resulted in all in ovo injected probiotic treatments increasing feed conversion ratio (FCR) from days 7 to 14 as compared to the control (P = 0.01). Differences in FCR were not observed in any other week of data collection (days 0 to 7, 14 to 21, or 0 to 21; P > 0.05). Although probiotics altered live performance from days 7 to 14, these data suggest that in ovo inoculations of L. animalis and E. faecium in combination are viable probiotic administration practices that potentially improve hatch characteristics and gastrointestinal tract development.