Selection response for part period egg number and egg mass in chickens — a comparison

Abstract

Two sublines from each of four flocks of White Leghorn were subjected to two cycles of selection for part year egg number and part year egg mass. A family index (combined selection) was the selection criterion for each of the two traits. The generation means of an unselected pedigreed randombred control, bred and maintained along with the selected sub-lines, were used for correcting short term environmental trends. The sublines selected for a common selection criterion were considered as replicates. The control corrected generation means, when averaged over replicates, gave the mean direct and correlated responses for the selected and different unselected traits. The average genetic change per generation was 2.16 eggs in egg number selected sublines and 146 g of egg mass in egg mass selected sublines. The direct response marginally exceeded the correlated response for both part period egg number and egg mass seen in the corresponding sublines. Except for egg weight the correlated responses for different unselected traits were in the same direction in both egg number and egg mass selected sublines. While the egg weight in egg number lines did not change, its response was positive in egg mass selected lines. A comparison between the lines revealed that the egg mass selected lines matured later and laid heavier but slightly less numerous eggs than the egg number selected sub-lines.

Effect of Early Selection for Body Weight, Keel Length and Breast Circumference on Egg Production Traits in Inshas Strain of Chickens

“…Responses observed in most selection experiments with egg mass as selection criterion suggested a slightly increased of direct response than correlated response. The same findings had seen in the corresponding selected sub-line of White Leghorn (Venktramaiah et al, 1986) they also reported that the egg mass selected sub-line matured later and lay heavier but slightly less numerous eggs. However, egg mass is estimated to be a low heritable trait ranged from 0.05 to 0.16 (Quadeer et al, 1977 andVenktramaiah et al, 1986).…”

“…The same findings had seen in the corresponding selected sub-line of White Leghorn (Venktramaiah et al, 1986) they also reported that the egg mass selected sub-line matured later and lay heavier but slightly less numerous eggs. However, egg mass is estimated to be a low heritable trait ranged from 0.05 to 0.16 (Quadeer et al, 1977 andVenktramaiah et al, 1986). The objective of this study is to use the best linear unbiased prediction method (BLUP) in predicting the breeding values of body weight, keel length and breast circumference and to use this information for increasing the selection response of egg mass in Inshas strain of chicken.…”

Response to Selection of Indigenous Chicken in Rwanda Using Within-Breed Selection Strategy

“…Genetic gain realised for individual traits differed between CBS and GBS (Table 3), and also between nucleus and commercial. Genetic gain per generation for BW observed in this study was positive and higher than 69.92g of IC in Tanzania [37] Tanzanian medium IC [37], 2.6 eggs for the Indian chicken ecotype [75] and 3.10 eggs for chicken in Nigeria [59]. These dissimilarities could be attributed to either population size considered, selection procedure used, or selection intensities employed [71].…”

Genetic Analysis of Egg Production and Allied Characters in Two Long Term Selected Strains of White Leghorn

“…Other traits however had inconsistent trends. Venkatramaiah et al, (1986) have reported a genetic response of 2.16 eggs per generation in White Leghorn.…”