ANALYSIS OF POULTRY FERTILITY DATA .3. ANALYSIS OF THE DURATION OF FERTILITY IN NATURALLY MATING JAPANESE-QUAIL

The purpose of the present study was to test the appropriateness of it erative least squares regression for the evaluation of fertility data in naturally mating quail. In each of four trials, 20 male and 200 fem ale randombred Japanese quail were housed in stacked breeder cages. Pa ired females were exposed to their assigned male for a single 48-h per iod. Eggs were collected for 2 wk following removal of the male, incub ated, and fertility determined by visual inspection at egg breakout. I n Trials 1 and 3, sexually experienced males were placed with experien ced and inexperienced females, respectively. In Trials 2 and 4, inexpe rienced males were placed with experienced and inexperienced females, respectively. Duration of fertility, by male, was analyzed by iterativ e least squares, using the model y(x) = gamma/(1 + e(beta(r-x))). Over all fertility was analyzed with a log odds model following transformat ion to logits. Iterative least squares provided estimates of fertility duration of 3.75 to 9.18 d, with significant (P < 0.05) differences i n the duration of fertility observed between individual males as well as between the trials. Differences (P < 0.05) in overall fertility (17 .7 to 58.3%) were also observed, with inexperienced males paired with experienced females exhibiting the lowest overall means. Taken togethe r, these results suggest that iterative least squares may be used to e valuate fertility in naturally mating populations and that reproductiv e experience can have a profound effect on the interpretation of ferti lity in naturally mating quail.