Genetic parameters for feed utilization traits in XXXX .

@entity5872 @entity1017 @entity41 @entity2883
Feed costs substantially affect the efficiency of poultry operations, justifying genetic improvement of feed utilization by selection. The current research was conducted to estimate genetic variance for the 4-wk feed conversion ratio (FCR) and its genetic correlations with BW, @entity1017 ( @entity2883 ), feed intake (FI), and @entity41 ( @entity41 ) in @entity5872 . The data analyzed originated from a line selected for low FCR for 3 generations. In each generation, 35 sires and 70 dams were used as parents for the next generation. Body weight and @entity2883 were recorded on a total of 1,226 individuals, whereas FCR, @entity41 , and FI were recorded on 505 family groups. The results showed that heritability estimates (  SE) of BW at 28 d of age and @entity2883 between 7 and 28 d of age were 0.22    0.05 and 0.28    0.06, respectively. For FI, FCR, and @entity41 , significant genetic variances were estimated. Genetic correlations of FCR between 7 and 28 d of age with @entity2883 and FI between 7 and 28 d of age were -0.45    0.09 and 0.24    0.08, respectively. This implies that a low FCR is genetically related to a high @entity2883 and low FI. The genetic correlation between FCR from 7 to 28 d of age and @entity41 from 7 to 28 d of age was 0.26    0.08, indicating that the 2 alternative feed efficiency traits are genetically different traits, and that the correlated genetic response in one of them in response to selection on the other is likely to be only moderate. Genetic correlations of @entity41 from 7 to 28 d of age with @entity2883 and FI between 7 and 28 d of age were 0.08    0.04 and 0.74    0.11, respectively. This reflects the fact that @entity41 is phenotypically independent of @entity2883 , which tends to make the genetic correlation between @entity41 and @entity2883 low as well. In conclusion, all the traits analyzed displayed significant genetic variance, allowing their genetic improvement by selection, yet the alternative feed utilization traits, FCR and @entity41 , displayed different genetic characteristics.
