Use of a sperm analyzer for evaluating broiler breeder males. 2. Selectionof young broiler breeder roosters for the sperm quality index increases fertile egg production

Previous research has shown that the sperm quality index (SQI) of rooster s emen is indicative of overall semen quality. The objectives of the present experiments were to determine the correlation of the SQI with semen charact eristics and fertility and to determine if selection of young males for the SQI would improve fertility. In Experiment 1 semen was collected from 35 P eterson males and was analyzed individually for sperm concentration and via bility. To determine fertility, 100 mu L of diluted semen was inseminated i nto 10 hens for each rooster. Positive correlations of the SQI with total a nd live sperm concentrations as well as fertility were found. A negative co rrelation of the SQI with the percentage of dead sperm was observed. Ln Exp eriment 2, four semen samples were collected at 2- to 3-d intervals from ea ch of 142, 27-wk-old Peterson roosters to determine their SQI. Males were t hen allocated to six treatment groups based on their average SQI readings a s follows: 0 to 150, 151 to 200, 201 to 250, 251 to 300, 301 to 350, and >3 50. For each SQI group, semen was collected weekly for 8 wk, pooled, and us ed at a rate of 50 mu L/hen to inseminate 40 hens. The percentage of fertil ized eggs increased linearly across the SQI groups, from a minimum of 65% f or the 0 to 150 SQI group to a maximum of 98% for the >350 SQI group. The S QI groups of 301 to 350 and >350 produced the slowest decline in fertility over days postinsemination. Therefore, selection of males for the SQI at an early age appears to improve flock fertility.