Evidence for the Association of a Deleted Variant in the 5′-Flanking Region of the Chicken serotonin transporter (5-HTT) Gene with a Temporary Increase in Feed Intake and Growth Rate

SIMPLE SUMMARY: The serotonergic system has been shown to be implicated in the regulation of mood and feeding behavior. Previous studies have identified a polymorphism in the 5′-flanking region of the serotonin transporter (5-HTT) gene of Lohmann Brown (LB) laying hens. In this study, the impact of three genotypes (W/W, W/D, and D/D) at the 5-HTT gene on feed intake and body weight was investigated. After hatching, hens of the three genotypes were kept under ad libitum feeding conditions, and their feed intake and body weight were recorded weekly. From 5 weeks of age, D/D and W/D hens were significantly heavier than wild-type W/W hens. Further, it is found that D/D hens had a temporarily higher feed intake and growth rate than W/W hens between 4 and 7 weeks. We suggest that the increased body weight is due to a transiently increased appetite of D/D hens. ABSTRACT: The serotonergic system has been shown to be implicated in the regulation of mood and feeding behavior. Previous studies have identified a polymorphism in the 5′-flanking region of the serotonin transporter (5-HTT) gene of Lohmann Brown (LB) laying hens. The deleted variant D was found to be associated with increased body weight. The objective of this study was to address whether the increased body weight may be due to an increased feed intake. After hatching, hens were kept under ad libitum feeding conditions, and their body weight and feed intake were weekly determined. From 5 weeks of age, the body weight of hens with the D/D and W/D genotypes was significantly greater than that of W/W carrying hens. Interestingly, we found that the feed intake of D/D carrying hens, relative to body weight, was transiently increased only between 4 and 7 weeks of age (p < 0.05), leading to a higher growth rate (p < 0.05), compared with that of W/W carrying hens. These results suggest that the presence of variant D may be correlated with a transiently increased appetite of D/D carrying hens.