Effect of enzymatically treated yeast in early feeding of broiler chickens on growth performance, organ weights, intestinal histomorphology and ceca microbial metabolites

A total of 480 d old (male) Ross x Ross 708 broiler chicks were placed in 24 floor pens (20 birds per pen) to evaluate the effects of feeding enzymatically treated inactivated whole yeast, derived from sugar cane bio-ethanol production, on growth performance and selected physiological responses in broiler chickens. Diets were formulated for a 5-phase feeding program: Pre-starter; d 0-6 Starter; d 7-15, Grower: d 16-28, Finisher 1; d 28-42 and Finisher 2; d 43-56. Yeast (LivaltaCell HY40, Livalta, UK) was applied in pre-starter and starter diets at 0.6 and 0.2%, respectively. Birds received a common diet from d 16 to 56. Feed intake (FI) and body weight (BW) were recorded by phase for calculation of BW gain (BWG) and mortality corrected FCR. On d 10, all birds received an oral dose of 25,000 E. acervullina and 5,000 E. maxima sporulated oocysts in 1 mL of sterile saline. On d 15, one bird per pen was sacrificed for organ weights (gizzard, small intestine, ceca, liver, spleen, liver, bursa), jejunal tissues for histomorphology and ceca digesta for microbial activity. On d 56, one bird per pen was sacrificed for organs and breast weight. In pre-starter phase, yeast fed birds showed better (P<0.05) BWG (10 g) and FCR than control fed birds. Combining pre-starter and starter phases, the FCR of yeast fed birds showed better FCR (1.117 vs. 1.126; P<0.05) than control. Although not statistically different, overall body weight gain (d 0-56) was 3.920 and 3.962 kg/ bird and corresponding values for FCR were, 1.808 and 1.755, for the control and yeast, respectively. Diets had no (P>0.05) effects on physiological responses evaluated on necropsied birds except that yeast fed birds did (P<0.05) have lighter bursa (g/kg BW) than control birds on d 15, indicating immune modulating effects of the yeast. The current data indicate that yeast can support growth in early life of broiler chickens, but these effects were not sustained after the transitioning birds to common grower and finisher diets.

Key Words: Enzymatically treated yeast, growth performance, gastrointestinal development, Broiler chickens.

Presented at the International Poultry Scientific Forum at IPPE 2022 in Atlanta, USA.