Detection and incidence of yellow turkey semen on commercial breeder farms.

Seminal plasma from 270 commercial Large White breeder turkeys (30 males from each of nine farms) was evaluated for protein concentration, color, and opacity. Yellow semen syndrome (YSS) was detected by identifying seminal plasma having both a yellow color and a high protein concentration (greater than 20 mg/ml) and was present in 11.8% of the males. Normal white semen males, with seminal plasma protein less than 20 mg/ml and white or slight yellow in color, were found in 85.9%. Using this method only 3.3% of the males did not fit either category. Protein concentrations were clustered near 10 mg/ml but values ranged from 3.7 to 79 mg/ml. A low protein group (less than 8 mg/ml; 13.3% of the males) had 34 white, 2 slight yellow, and 0 yellow samples. A median protein group (10 mg/ml; 74.1%) had 175 white, 21 slight yellow, and 4 yellow. The high protein group (greater than 20 mg/ml; 12.5%) had 2 white, 14 slight yellow, and 18 yellow. There was large variation among farms, ranging from 0% to 23.3% YSS. Protein concentration was not correlated with the age of the males, and opacity of the seminal plasma was lowly correlated with color (r = .17; P less than .01). Refractive index was useful for estimating the seminal plasma protein concentration (r = .87; P less than .0001), which along with color, could be used as a simple method for estimating the quality of turkey semen on the farm.