Comparative Intestinal Histological Features Observed in 1940 Leghorn vs. 2016 Leghorn-Based Commercial Laying Hens Fed Representative Diets

Author(s): Dannica C Wall, Ramon D. Malheiros, Kenneth (Ken) Anderson, Nick Anthony

Nutrient absorption is essential for all stages of life and production in Leghorn hens. The selection for production traits, specifically linked to promoting digestive utilization of feed, has resulted in improved feed efficiency and ultimately increased egg production. Digestion of ingested feed and nutrient absorption takes place within the small intestine by the crypts and villi of the absorptive epithelium, specifically in the crypts and microvilli. Understanding the absorptive epithelium and its structural changes, related to genetic selection and improved feed efficiency, is important for continued efforts to improve egg production. The objective of this study was to determine and compare the histological changes in the duodenum, jejunum, and ileum of the 1940 Leghorn vs. the 2016 Leghornbased commercial laying hens fed diets representative of those fed by the industry during the respective years of production.

In order to compare the effect of dietary regimen on intestinal histology, a total of 320 White Leghorn laying hens of two different strains were distributed into a 2 × 2 factorial arrangement. The factors were diet and strain: 1940 diet, 2016 diet, 1940 layer, and 2016 layer. The 4 experimental treatment groups: 1). 2016 hen on 1940 diet, 2). 2016 hen on 2016 diet, 3). 1940 hen on 1940 diet, and 4). 1940 hen on 2016 diet with 8 replicates per treatment. Five villi samples for histological analysis were taken from the three segments of the small intestine: the duodenum, jejunum, and ileum, and analyzed from 12 birds representing each treatment. Histologically the villus height, epithelium height, crypt depth, mucosal enlargement factor, and the tunica muscularis thickness were measured in the duodenum, jejunum, and ileum. The experiment was a completely randomized design, and all data were analyzed with a one-way analysis of variance (ANOVA). Tukey’s test was applied to compare the significance of differences between the means. Statistical significance was considered at P< 0.05. Significant differences were demonstrated among all treatment groups for the duodenum, jejunum, and ileum. Results from this data suggest that the functionality of the small intestines possibly influences response to dietary manipulations. Further studies are necessary to evaluate the effects of diet on intestinal functionality and nutrient digestibility.