Fertility of broiler breeders following categorization by the OptiBreed sperm quality index when hens are inseminated with a constant number of sperm

Poultry Science Department, Mississippi State University, Mississippi State 39762, USA.

If semen quality was known prior to insemination, sperm doses could possibly be decreased, maximizing the number of hens inseminated. The sperm quality index (SQI), an indicator of overall semen quality, is determined by the number of deflections in a light path due to sperm movement inside a capillary tube. The objectives of this study were 1) to determine the age at which the SQI becomes a static predictor of semen quality and 2) to determine if fertility of males with a higher SQI responds more favorably to insemination dose reduction than that of males with a lower SQI. Weekly from 23 to 32 wk of age, 144 Cobb males were tested for SQI. At 32 wk of age, males were placed into four groups that represented the SQI population quartiles as follows: poor, fair, good, and best. A fifth SQI group, uncategorized, was created to determine fertility of the original population by mixing equal amounts of semen from each of the four groups. Semen was collected weekly from 33 to 40 wk of age from 18 males in each of the four groups, pooled by group, and used to inseminate 30 hens per group with 50 or 100 million sperm. Eggs were collected daily, incubated, and broken out to determine fertility. Correlation coefficients between weekly SQI results and overall averages for individual males indicated that the SQI stabilized after the birds were 28 wk of age. The main effect for SQI selection revealed that the best SQI group had the highest fertility (88%), which did not differ from the good (83%) or fair group (82%) but was greater than the uncategorized group (80%). Fertilities of the top three groups and the uncategorized group were higher than the poor group (63%) (P < 0.0001, SEM 2.18). In addition, there was an interaction between SQI classification and insemination dose. Fertilities of the top three SQI groups were similar at the 50 and 100 million sperm doses. However, the poor and uncategorized SQI groups had lower fertility at the 50 million dose as compared to the 100 million dose. By categorizing males into SQI groups after 28 wk of age, insemination dose can be reduced, maximizing a male's fertilizing potential.

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