Effect of selection for fertility of frozen-thawed semen in chickens on the fertility of fresh and stored semen.

Studies were conducted using 68 males from the seventh generation of a line of meat-type breeder chickens selected for increased duration of fertility of frozen-thawed semen and 69 males of the randomly selected control line. These chickens were used to determine the presence or absence of differences between the selected and control lines with respect to fertility and spermatozoal motility when the semen was subjected to the following preinsemination treatments: 1) frozen in a diluent containing 13.6% glycerol; 2) frozen in a diluent containing 1.7% glycerol; 3) fresh undiluted; 4) fresh diluted; 5) diluted and stored for 24 hr; and 6) diluted and stored for 48 hr. Semen from each male was inseminated into 4 to 6 White Leghorn tester hens per experiment. The effects of genotype (line) by preinsemination semen treatment interaction on fertility and spermatozoal motility were also examined. When semen was frozen (Treatments 1 and 2), the selected line had significantly (P less than .01) higher duration of fertility, percent fertility for 7 days postinsemination, and percent fertility for the duration of fertility and spermatozoal motility than the control line. For fresh semen (Treatments 3 and 4), the selected line had significantly (P less than .01) higher fertility estimates and spermatozoal motility than the control line except for percent fertility for the duration of fertility (P greater than .05) of undiluted semen. For stored semen (Treatments 5 and 6), the selected line only had significantly (P less than .05) higher duration of fertility after 24 hr storage and percent fertility for the duration of fertility after 48 hr storage than the control line.(ABSTRACT TRUNCATED AT 250 WORDS)