Riboflavin and Bacillus subtilis effects on growth performance and woody-breast of Ross 708 broilers with or without Eimeria spp. challenge
This study was conducted to assess the effects of the dietary supplementation of riboflavin (as a bile salt hydrolase (<strong>BSH</strong>) inhibitor) and <italic>Bacillus subtilis </italic>on growth performance and woody breast of male broilers challenged with <italic>Eimeria </italic>spp. Intestinal bacteria, including supplemented probiotics, can produce BSH enzymes that deconjugate conjugated bile salts and reduce fat digestion. A 3 × 2 × 2 (riboflavin ×<italic>Bacillus subtilis </italic>× <italic>Eimeria </italic>spp. challenge) factorial arrangement of treatments in randomized complete block design was used. On d 14, birds were gavaged with 20× doses of commercial cocci vaccine (Coccivac<sup>R</sup>-B52, Merck Animal Health, Omaha, NE). Dietary treatment of riboflavin and <italic>B. subtilis</italic> did not affect body weight (<strong>BW</strong>), body weight gain (<strong>BWG</strong>), and feed conversion (<strong>FCR</strong>) d 0 to 14 and overall d 0 to 41. <italic>Eimeria</italic> spp challenge reduced BWG, FI, and increased FCR between d 14 to 28, but increased BWG and lowered FCR between d 28 to 35. There were no effects of the <italic>Eimeria </italic>spp<italic>.</italic> challenge on the overall d 0 to 41 FCR and FI, but BWG was reduced. <italic>Eimeria spp.</italic> challenge increased the abdominal fat pad weight and slight woody breast incidences on processed birds on d 42. Dietary inclusion of <italic>B. subtilis</italic> and riboflavin at tested levels did not help birds to mitigate the negative impact of <italic>Eimeria</italic> spp. challenge to enhance the growth performance.