Differences in growth and fat deposition between White Plymouth Rock and Nagoya breeds as a tool for QTL analysis

Abstract

Two breeds of chickens were used in this study White Plymouth Rock(WPR( and Nagoya (NAG) in addition to tracking of their crossbred (♀WPR Χ ♂ NAG) of two generations (F1and F2) for evaluating thedifferences in growth characteristics and fat deposition. Body weights weremeasured weekly from the first day (hatch day) till 4 weeks of age anddifferent weight gains were also calculated. In addition to feed intake (forthe period of 3-4 weeks of age) and feed conversion ratio were estimated.At four weeks of age, birds were dissected and the major internal organsincluding liver and gizzard were weighed, moreover the parts of breastmuscle were also recorded. The results showed that, WPR wassignificantly higher in body weights, body weight gains and feed intakethan NAG chicken. Also, WPR showed significantly larger sizes for liver,gizzard, pectoral muscles, abdominal fat (AF), ventriculus fat (VF),subcutaneous fat (SF) and total fat weight than NAG chicken. Thecorrelation analysis showed that body weight at one week of age and bodyweight gain of the first week of age were found to have positive correlationwith liver triglycerides and serum triglycerides levels in WPR while it wasassociated with decreasing of level of total cholesterol in serum in NAG.These results served as evidence for elucidating the major differencesobserved between the two breeds concerning growth and fat deposition. Inaddition to the relationship between increasing body weight and fatdeposition was established. Thus, future QTL analysis can be performedfor identification of chromosomal regions controlling growth and fatnesstraits and subsequently candidate gene influencing these traits could berevealed in further investigations.