Effects of Mating Ratio, Cock Number in the Flock and Breeder Age on Fertility in Thai Native Chicken Flock

Abstract

Trials were conducted to determine general semen characteristics of the male native chicken and effects of mating ratio, cock number in the flock, and breeder age on fertility in the native chicken flock. The results revealed that the mature native male had the semen volume of about 0.4 ml/bird/ejaculation, spermatocrit value of about 13.86-15.60%, semen concentration of about 7031-8001 million cells/ml, and total sperm of about 2870-3200 million cells/ejaculation. The motility score and pH value were around 4-5 and 7.7-8.4, respectively. The effect of mating ratios on fertility of the flock was not significantly different (P>0.05). The mean fertility rates measured during 35-44 weeks of (hen) age of the mating ratios of 1:7,
1:10, 1:13, and 1:16 were 88.21, 91.20, 88.20 and 79.82% ; and during 34-44 weeks of age of the mating ratios of 1:8, 1:12, and 1:16 were 84.31, 90.84, and 81.76% , respectively. The evidence which the lower trend of fertility rate occurring in the 1:16 flock disappeared after the exchange of cocks between the flocks indicated that sexual competency of the male played a major role in fertility of the breeding flock. Continuous surveillance on egg incubation results and immediate replacement of the ill with the healthy cocks wherever needed were suggested. Housing two cocks within
a flock showed ambiguous influence. While it caused a decrease in fertility percentage on the 1:8 flock, it showed no ill effect at all on the 1:16 flock. Furthermore, the incidence of low fertility observed in the 1:12 flock when its sole male was ill confirmed that the high fertility of the flock depended heavily on sexual competency of the male and it could possibly have been secured if there were two cocks in the flock. The results revealed more of the benefit of housing two cocks within the same flock. The declining fertility rate of the old hens in their third year of age was greatly improved from the mean value of 58.32% for the flock with one cock to 81.20% for the flock with two cocks. For the effect of breeder age on fertility, the overall
results of these experiments indicated that the native cocks aged from nine months to two years had similar fertilizing ability of about 80-90% whereas the native hens had their fertilizing ability decreased annually from about 80-90% in the first year, to about 70-80% in the second year, and 60-70% in the third year.