Artificial insemination in the hen. Physiological basis and control of the fertilizing rate of eggs

Abstract

In the hen, artificial insemination (A.I.) may incur twice the labour cost than natural mating and 10-25 % more investment in cages, but the cost of chicks is reduced (- 10 %). Furthermore they are of better breeding value, more vigorous and heavier at hatching, and having a higher growth rate (+ 50 g at 41 days old). The poultry industry is therefore becoming more and more interested in A.I. In fact, the benefits of A.I. are : a) the number of cockerels can be reduced to 1-3 per 100 hens, instead of 8-12 with natural mating ; b) the fertilizing rate of eggs is improved (particularly during the second half of the reproductive period) ; c) males and females can be raised separately (under conditions of lighting and feed specifically adapted to each sex) and in cages (better sanitary conditions, better control of food consumption, possibility of culling low performing breeders). To succeed with A.I., semen collections must be performed frequently (5 times a week) ; and the number of inseminated sperm (100 to 200 million per A.I. dosis) and the frequency of insemination (1 per week, on average) must be adjusted according to the age and the breed of females. Furthermore, the inseminations must never be performed 4 hours before or 4 hours after oviposition, this period being a time of high uterovaginal motricity which is liable to expel most of the inseminated sperm. One of the most important elements is a well-trained A.I. staff, able to work carefully at a high rate over long periods (for instance, 1,500 A.I. a day for 40 consecutive weeks). Producers have been able to meet these working criteria in other avian species (turkeys, guinea-fowl and ducks).