Growth performance and spleen and bursa weight of broilers fed yeast beta-glucan

Abstract

This study evaluated the efficacy of a yeast beta-glucan product (YBG) as a growth-promoting feed ingredient for broilers. Two trials were conducted with day-old chicks assigned to 24 pens (38 birds/pen) and one of three diets: no growth promotant, virginiamycin, or YBG. On days 14 and 38, two birds per pen were euthanized and the spleen and bursa of Fabricius were removed. In the first trial, body weights of birds from each treatment were the same until 38 d, when control birds were smaller (P < 0.05). In the second trial, 38-d body weights were the same for all treatments. A third trial was conducted with half the number of pens per treatment. In the third trial, controls were smaller than YBG at 38 d, but not smaller than virginiamycin. Feed conversion was not affected by diet in trials 2 and 3 but for trial 1 the control birds had poorer conversion than virginiamycin (P < 0.05), but not worse than YBG. Spleen weights were not different between treatment groups. Bursa weights decreased with age for all treatments in trials 2 and 3, but not in trial 1 for controls. These results indicate that YBG is as effective as virginiamycin in promoting growth of broiler chickens. Key words: Broiler chicken, antibiotic, yeast, beta-glucan, growth promotion