Nutritional strategies to mitigate sub-clinical coccidiosis in Eimeria-challenged broilers

Coccidiosis is one of the major enteric diseases in broilers, especially with increasing restrictions on the routine use of dietary coccidiostats. Although vaccines are available, their cost limits widespread use. This study aimed to investigate whether various nutritional strategies could reduce the effects of sub-clinical Eimeria infection in broilers. A total of 576 one-day-old male Ross 308 broilers were randomly assigned to one of eight dietary treatments, with six replicate pens per treatment and 12 birds per pen. The treatments included an unchallenged negative control (NC), a challenged positive control (PC), and six challenged dietary groups named: post-pellet whole wheat (WW), xylo-oligosaccharide (XOS), high fat (HF), high carbohydrate (HC), threonine combined with branched chain amino acids (Thr+BCAAs), and sodium butyrate (SB). On day 14, birds in the challenged groups were orally gavaged with 5,000 oocysts each of Eimeria maxima and E. acervulina in 1 mL of phosphate-buffered saline (PBS) and NC birds received PBS only. Performance data were collected to calculate feed conversion ratio (FCR) for each feeding phase. Fecal samples were collected on days 17-28 to assess oocyst shedding. Mild Eimeria challenge was confirmed by significant differences in lesion scores and oocyst counts (P < 0.05), with no difference in mortality between challenged and unchallenged treatments. Xylo-oligosaccharide, HC, and SB treatments helped to maintain bird's growth performance (P < 0.001) compared to the NC group. High fat and Thr+BCAAs supplementation increased cecal Bacteroides spp. (P = 0.004) compared to PC group on day 35, while XOS and HC supplementation numerically reduced fecal oocyst counts. Overall, dietary supplementation of XOS, HC, and SB showed potential to alleviate negative impacts of coccidiosis in broilers, warranting further investigation.