Dietary ascorbic acid and chromium supplementation for broilers reared under thermoneutral conditions vs. high heat stress

Abstract

The present study evaluates the effect of dietary ascorbic acid and chromium (AACr) on performance and microflora balance of broiler reared under thermoneutral conditions (TN) vs. high heat stress (HS). Two experiments were conducted on 112 Cobb 500 broilers, assigned in two experimental groups (28 chickens/group) and housed in an environmental controlled hall. Two groups (C-TN and AACr-TN) were kept in thermoneutral conditions. In the second experiment, other two groups were kept (C-HS and AACr-HS) in high heat stress (32° C). The structure of diets was the same in both experiments. Compared with the control diet (C), the experimental diet included the addition of a premix with 25 g ascorbic acid / kg premix + 20 mg chromium picolinate/ kg premix (AACr). At the end of the experiment, 8 broilers / group were slaughtered and samples of intestinal and caecal content were collected for bacteriological assessment. Dietary AACr did not affect (p>0.05) body weight, daily feed intake, feed conversion rate neither under TN nor under HS condition. The use of AACr in broiler diet led to a significantly reduction of staphylococci in the caecum. Both in caecum and intestinal content of AACr broilers, irrespective the temperature conditions the number of lactobacilli was significantly higher than in the C broilers. Combination of ascorbic acid and Cr (AACr) has a positive effect in limiting the development of the pathogenic bacteria colonizing the intestine and caecum during the heat stress.