Over the past decades, genetic improvements have stimulated broiler production resulting in birds weighing ± 3kg in 42 d. To reach this genetic potential, the absorption and digestion of nutrients and according morphological and functional development of the small intestine in the early life must be impeccable. Before hatch, uptake of nutrients by the chicken embryo is limited but rapid increase in villus length and formation of intestinal crypts, have been reported close to hatch and during the first 8 to 10 d of life. Considering the rapid development of the small intestine, it was the objective of this study to evaluate the effect of different concentrations of 2 yeast extracts on gut development in early life. Two thousand three hundred and four (2304) day-of-hatch male broiler chicks (Ross308) were divided into 7 treatment groups with either 6 or 7 replicates of 40 birds each. Broilers were fed at libitum from hatching until 14 d of age, a control diet (non-supplemented control) or the control diet supplemented with either yeast extracts A or B at increasing concentrations (125, 250 and 500 g/ton of feed). At d 6, 2 randomly selected birds per replicate were sacrificed to investigate gut morphology in the duodenum, jejunum and ileum. Cryostatic slides were prepared and treated with periodic acid-Schiff to stain mucus glycoproteins. Villus length and number of goblet cells were measured in micrographs of known magnification. Statistical analysis was performed by Student’s t-test comparing the mean values of the treatments with the non-supplemented control. In the duodenum, supplementation of both yeast extracts at 125 and 250 g/ton, resulted in an increased villus length. Additionally, supplementation of yeast extract A at 250 g/ ton was also able to increase villus length in the jejunum. No difference on either crypt depth or villus/crypt ratio could be found. Goblet cell counts were increased with supplementation of both yeast extracts at 250 and 500 g/ton in both duodenum and ileum. It can be concluded that the inclusion of yeast extracts in the diet have beneficial effects on the gut development by increasing the absorptive area and mucus layer.
Key Words: early gut development, gut morphology, yeast extract.