Artificial insemination (AI) is widely used to overcome low fertility in turkeys, which results from unsuccessful mating as a consequence of large, heavily muscled birds or of reduced libido. This is a serious and costly problem in the production of hatching eggs. AI has not found wide application in commercial chicken production but is routinely used in special breeding work and research.
Collecting semen from a chicken or turkey is done by stimulating the copulatory organ to protrude by massaging the abdomen and the back over the testes. This is followed quickly by pushing the tail forward with one hand and, at the same time, using the thumb and forefinger of the same hand to “milk” semen from the ducts of this organ. Semen flow response is quicker and easier to stimulate in chickens than in turkeys. The semen may be collected with an aspirator (turkeys) or in a small tube or any cup-like container. In turkeys, the volume averages ∼0.35–0.5 mL, with a spermatozoon concentration of 6 to >8 billion/mL. In chickens, volume is 1–2 times that of turkeys, but the concentration is about one-half. Collected semen is usually pooled and diluted with an extender prior to use.
Chicken and turkey semen begins to lose fertilizing ability when stored >1 hr. Liquid cold (4°C) storage of turkey and chicken semen can be used to transport semen and maintain spermatozoal viability for ∼6–12 hr. This short-term storage of semen is common in turkeys, while not as common in chickens. When using liquid cold storage for >1 hr, turkey semen must be diluted with a semen extender at least 1:1 and then agitated slowly (150 rpm) to facilitate oxygenation; chicken semen should be diluted and then cooled—agitation is not necessary. Chicken and turkey semen may be frozen, but reduced fertility limits usage to special breeding projects. Under experimental conditions, fertility levels of 90% have been obtained in hens inseminated at 3-day intervals with 400–500 million frozen-thawed chicken spermatozoa.
Several commercial semen extenders are available and are routinely used, particularly for turkeys. Extenders enable more precise control over inseminating dose and facilitate filling of tubes. Results may be comparable to those using undiluted semen when product directions are followed. Dilution should result in an insemination dose containing ∼300 million viable spermatozoa for turkeys. However, the number of spermatozoa inseminated will range from 150–300 million viable cells depending on the age of the turkey hens inseminated. In chickens, the number of diluted semen inseminated will range from ~100–200 million sperm cells. Producers will usually determine the spermatozoa concentration and dilute the semen to obtain the appropriate sperm cell concentration for either the turkey or chicken.
For insemination, pressure is applied to the left side of the abdomen around the vent. This causes the cloaca to evert and the oviduct to protrude so that a syringe or plastic straw can be inserted ∼1 in. (2.5 cm) into the oviduct and the appropriate amount of semen delivered. As the semen is expelled by the inseminator, pressure around the vent is released, which assists the hen in retaining sperm in the vagina or oviduct. When inseminating undiluted turkey semen, the high sperm cell concentration allows for 0.025 mL (∼2 billion spermatozoa) to be inseminated at regular intervals of 10–14 days, yielding optimal fertility. In chickens, due to the lower spermatozoon concentration and shorter duration of fertility, 0.05 mL of undiluted pooled semen, at intervals of 7 days, is required. The hen's squatting behavior indicates receptivity and the time for the first insemination. For maximal fertility, inseminations may be started before the initial oviposition in turkeys, while this is not necessary in chickens. Fertility tends to decrease later in the season; therefore, it may be justified to inseminate more frequently or use more cells per insemination dose as hens age.
Last full review/revision March 2012 by R. Keith Bramwell, BS, MS, PhD