Annual variation in semen characteristics of pigeons (Columba livia)

The purpose of this study was to evaluate annual semen characteristics of pigeons (Columba livia). Ten selected male pigeons, aged 2 to 5 yr were housed under natural environmental conditions, and semen collection was conducted via a digital massage twice weekly throughout the year. The success rate of semen collection in a total of 920 attempts was 40% (371/920) over the whole year. The highest success rate was 69% (55/80) in March followed by 66% (53/80) in November, whereas the lowest rates were in August (13%,10/80) and September (13%, 8/60) (P < 0.01). Volume of the ejaculate averaged 11.0 +/- 0.9 microL (mean +/- SEM). The greatest volume was obtained in November (13.5 +/- 1.0 microL), whereas the least was obtained in August (7.0 +/- 1.0 microL). The average sperm motility was 72 +/- 2% of all ejaculates, of which the highest motility (82 +/- 2%) was observed in March, whereas the least motility (48 +/- 3%) was in August. Sperm viability and sperm motility were positively correlated (r = 0.91; P < 0.01). Maximum sperm concentration was 4.9 +/- 0.4 x 10(9) sperm/mL noted in March, whereas the minimum was 3.8 +/- 0.2 x 10(9) sperm/mL observed in October. Donors generally exhibited susceptible (54%) or dull submission (43%), whereas resistance to handling was rarely observed (3%). During collections, a red (47%) or pink (44%) cloacal membrane was often observed, whereas during only 9% of the collections, the cloacal membrane was pale. When the ambient temperature decreased below 15 C, semen could not be obtained (0/80). A high amount of semen (>10 microL) was obtained when the temperature ranged between 19 and 24 C. Optimal sperm motility (approximately 80%) and viability (>85%) was observed when the temperature was between 18 and 24 C. At temperatures greater than 28 C, sperm motility and viability decreased. Sperm concentration was not significantly influenced by temperature fluctuations. In summary, annual variation in semen characteristics exhibited two peaks per year with mean motility and viability reaching peak annual values in March and November. Both of these months had mean ambient temperatures between 19 and 24 C, a range associated with maximal ejaculatory volumes.