Short-term selection for body weight and growth rate in japanese quail 2. Correlated responses

Abstract EN

Three quail lines were used in this work to evaluate the correlated responses of growth and some fitness traits in Japanese quail after mass selection for increased either weight or growth rate : HBW42 line was selected for high body weight at 42 days of age, HGR1-42 line was selected for high growth rate during the period from one-day to 42 days of age and random bred control line RBC was used as non-selected pedigreed population.

The results obtained can be summarized as follows : The highest correlated responses of body weights were attained in the 1st generation for BW1 and BW35 associated with faster GR21-42.

The highest fertility and hatchability percentages either calculated from total egg set (HTE% ) or fertile eggs (HFE%) were obtained after one generation of selection.

Asymmetrical correlated responses between the two sexes were found and were not stable throughout the three generations.

Selection for HBW42 resulted in increases in body weights at 14, 21, 28 and 35 days of age and faster growth rate during the period from 1-21 days than other lines.

However, the HGR1-42 line had heavier body weights at 7 and 42 days of age than other lines.

Significant line differences favoring HGR1-42 followed by HBW42 were attained for fertility%, HTE% and HFE%.

Correlated responses in the line HGR1-42 were higher but insignificant than that for the HBW42 line for males and females.

However, females had higher correlated response in BW7 with significant sex differences in the HBW42 and HGR1-42 lines.

Generally, the realized correlated responses of all studied growth traits in males were positive and higher than their expected correlated responses.

The highest realized correlated responses were 4.97 in BW35 of the HBW42 line and 4.76 in BW42 of the HGR1-42 line.

Realized correlated responses in all body weights from 7 up to 42 days of age for the HGR1-42 line, except BW1 were significantly higher and positive than their expected estimates, whereas the realized correlated responses in growth rate traits of this line were insignificantly different than their expected estimates.

The highest correlated responses for females were 7.21 and 5.86 for BW21 in the HBW42 and HGR1-42 lines, respectively.

The realized correlated responses were insignificantly lower than expected estimates for all fitness traits in the line selected for HBW42.

Similar trend was observed for fitness traits except HTE%, which indicated highly significant differences favoring realized correlated responses as a result of selection for HGR1-42 .

It can be concluded that selection for high growth rate is more effective than selection for body weight because both insignificantly differed from each other for all growth traits and the survivability during the periods from 1-21 and 1-42 days of age.

Besides, there are significant differences favoring HGR1-42 line for fertility% and hatchability% which calculated as a percentage of total eggs or as a percentage of fertile eggs, which can be used as additional indirect goals from selection in that line.