Influence of spermatozoa numbers and insemination frequency on fertility in dwarf broiler breeder hens.

The effects of hen age (28 to 31 vs. 49 to 52 weeks of age), sperm concentration (dose used for artificial insemination), and frequency of insemination on fertility and embryonic survival of dwarf broiler breeder hens were examined. Hens in Groups 1 and 2 were inseminated weekly with single doses of either 250 million (Group 1) or 125 million (Group 2) sperm during the 4 weeks of each period. Hens in Groups 3 and 4 were inseminated every other week with duplicate doses on 2 consecutive days, with 250 million sperm/dose in Group 3 and 125 million/dose in Group 4. Hens in Groups 5 and 6 were inseminated weekly with either 250 million (Group 5) or 125 million (Group 6) sperm dose, except the 1st week of each period when they received duplicate doses as in Groups 3 and 4. In Groups 1 and 2, insemination with weekly single doses of semen (250 or 125 million sperm) had no significant effect on fertility of young or old hens. Percent fertility during the 2nd week after artificial insemination was lower in Group 4 than in Group 3 (73.0 vs. 82.9 in young hens and 70.4 vs. 80.7 in old hens). There were no significant differences in fertility between semen doses or age periods in Groups 5 and 6. In these two groups, overall fertility ranged from 94.3 to 95.9%. Complementary studies on individual fertility and embryonic survival showed the beneficial effects of duplicate followed by single inseminations of moderate doses (125 million sperm) practiced at weekly intervals in old hens. This method should be of practical application in commercial practice.