Munene Kithama

Alternative feed additives are being investigated due to the restriction of antibiotics use to decrease antimicrobial resistance (AMR) in food-producing animals. This study investigated the effects of dietary American cranberry (Vaccinium macrocarpon) and wild blueberry (V. angustifolium) pomaces on the cecal microbiota and resistome profiles as well as the short-chain fatty acid levels. Male broiler chickens Cobb500 were fed a basal diet with either 55 ppm bacitracin methylene disalicylate (BMD); 0.5% (CRP0.5) and 1% (CRP1) cranberry pomace; and 0.5% (LBP0.5) and 1% (LBP1) lowbush blueberry pomace with or without a multienzyme mixture (ENZ). The results showed that at 21 days of age, the total coliform counts decreased in the CRP0.5-fed birds compared to BMD (p < 0.05). The use of pomace significantly increased the abundance of Lactobacillus and Bacteroides regardless of ENZ, while CRP decreased the Proteobacteria phylum abundance. In-feed ENZ tended to increase the relative abundance of genes conferring aminoglycoside resistance. Treatment with CRP0.5 decreased the abundance of cepA genes encoding for macrolide (MACROLIDE) and lincomycin (InuD) resistance while increasing those for tetracycline (tetO and tetX) resistance. These results showed, for the first time, the potential of the studied enzymes in influencing berry pomace’s effects on antimicrobial resistance gene profiles in broilers.

We previously reported that high levels (≥50%) of black soldier fly larvae meal (BSFLM) reduced growth and altered organs morphology in broiler chickens. Herein we further examined gastrointestinal, breast, bone, plasma, and litter attributes in broiler chickens fed partial to complete replacement of soybean meal (SBM) with BSFLM. A total of 1152 day-old Ross × Ross 708 male chicks ( n = 8) were allocated to 48 pens and assigned one of six diets: a basal corn-SBM diet (0BSFLM), four diets in which SBM in 0BSFLM was replaced with BSFLM at 12.5%, 25%, 50%, and 100% (12.5BSFLM, 25BSFLM, 50BSFLM, and 100BSFLM) and a final diet (0 + AGP) in which 0BSFLM was fed with coccidiostat and antibiotic. Birds were bled for plasma and necropsied for samples. Litter samples were collected on days 45 to 47. Breast weight, woody breast, and hardness scores and tibia morphometry reduced linearly in response to BSFLM inclusion ( P < 0.001). BSFLM linearly increased plasma Lys, Met, Thr, uric acid, creatine kinase and decreased Arg and potassium ( P < 0.05). Litter ammonium nitrogen and potassium decreased linearly in response to BSFLM ( P < 0.001). In conclusion, the data suggested physiological and metabolic inefficiencies in broiler chickens fed isocaloric and isonitrogenous diets with ≥50% BSFLM replacement of SBM.