Timing and Interval Effects of Repeated Inseminations by Roosters on the Fathering of Chicks.

The present study investigated the effects of timing and intervals between repeated inseminations by different rooster breeds on the fathering of chicks. The semen from Barred Plymouth Rock (BP), Japanese Silkie White (JS), and White Plymouth Rock (WP) males were used. Eighteen hens (7-month-old BP) were divided into four Groups (A-D). In all groups, the hens were first inseminated with the semen from BP males at 3 pm on day 0. The hens in Group A (=3) were inseminated with the semen from JS and WP males at 3 pm on days 5 and 10, respectively. Those in Group B (=3) were inseminated with the semen from JS and WP males at 3 pm on days 5 and 15, respectively. The hens in Group C (=6) were inseminated with the semen from JS and WP males at 6 am on days 5 and 10, respectively. Lastly, those in Group D (=6) were inseminated with the semen from JS and WP males at 6 am on days 10 and 20, respectively. The chicks obtained were classified on the basis of their phenotype matching with the breeding male phenotype. The majority of chicks (82.4% to 100% in Groups A and B) were fathered by the sperm from the subsequent insemination when repeated insemination was performed in the afternoon. Moreover, the chicks produced by the most recent insemination in the groups that were subjected to morning insemination could be obtained the next day after insemination (Groups C and D). The percentage of chicks fathered by the sperm from the subsequent insemination was 95.2% to 100% when the inter-insemination interval was 10 days (Groups B and D); these percentages decreased when the duration of the interval between inseminations was decreased to 5 days in Groups A, B, and C.