- Background of the study
Turkey, a large poultry bird, is fast gaining popularity among peasant farmers in the country to the extent that they are produced throughout the year for commercial purpose. All over the world Turkey is produced by breeders due to its body size, comformation and edible meat yield. Reproductive traits like its oviparous nature and low to medium fertility have not prevented a reasonable rate of improvement under natural condition even in developing countries (Esminger, 1977).Following the quest for massive production of animals like pigs, rabbit and poultry with short reproduction cycle as a major remedy to acute animal protein shortage in Nigeria, emphasis is placed on poultry and its products because they are acceptable to almost all peoples, religions and communities. Among all the species of poultry in Nigeria, turkeys appear to be the less distributed with a population of (0.2 million) (FDLPCS, 1992).
However, it is highly cherished due to its large body size and high meat quality. In Nigeria, about 90% of turkeys are produced for Christmas market mainly for these reasons (Smith, 1990; Veg.Soc.2007).
Although this may be the case, the scanty distribution of turkey in the peri-urban and rural areas of the country calls for serious concern. A notable reason for low distribution of turkey could be its reduced fertility compared to chicken, which factor places serious constraints to its rapid development especially under peasant farming conditions. The natural characteristic of male turkey (large body size) often results to reduced libido and low fertility which discrepancies cause toms not to mate frequently thereby resulting to low reproductive efficiency in turkeys under natural mating conditions.
The development of artificial insemination technology over the past decades has resulted in some significant advances in Turkey breeding. The objective of turkey artificial insemination programme is however not to produce fertile eggs but to produce viable poults (Murray, 1993). The US turkey industry relies on artificial insemination for the production of 300 million turkey annually (William, 2003). In developed world where artificial insemination is exclusively used to achieve acceptable level of fertility, donor toms as a rule are subjected to semen quality evaluation for fertility prediction (Donoghue, 1998). This idea coupled with the improvements on the technique of avian semen storage at ambient temperature, has led to increased multiplication of turkey in developed parts of the world. The situation is rather different in developing countries where these techniques are not adopted and producers have to rely on natural mating and egg hatching techniques to produce poults. Nigeria is one of such developing countries where the use of Artificial Insemination (AI) is still at the experimental stage such that turkey poults are imported for rearing and natural methods are applied on existing local stock to produce poults for turkey meat production.
1.2 Statement of the problem
It is well known that male breeders (stags) are usually bred for large body size and become too broad breasted and heavy to mate naturally with the comparatively smaller hen. The accompanying results in the inability of males to complete mating sessions successfully, causing low fertility under natural mating condition. Apart from this, ejaculated turkey spermatozoa is reported to perish after several minutes outside its own seminal fluid (Free potent soline.com 2001) and rapidly lose viability and fertilizing capacity when stored either undiluted or diluted at physiological temperatures (Leighton et. al., 1969; Lake and Ravie, 1982). AX et al. (2000) also reported that the survival of turkey ejaculated sperm in seminal plasma alone is limited to a few hours. As such its fertilizing ability is impaired or hampered and this often results to low production of poults.
In turkey breeding there is need to prolong the viability and duration of the fertilizing capacity of turkey sperm for genetic improvement and economic advantage. There is also the need to have repeatable techniques necessary to maintain the fertilizing potential of ejaculates from 6 to 24 hours under field condition. It is necessary to develop effective techniques for semen collection, dilution and insemination in the field to solve the problem of infertile mating under natural conditions for the benefit of small and large scale turkey producers in the country.
The use of Artificial Insemination technique in commercial poultry production is relatively recent compared to its use in cattle production. It has been applied mainly in turkey breeding and used to a lesser extent in chicken (Sexton, 1979).
The gap created by minimum use of this technique in the poultry industry in the tropical environment must be breached for maximum productivity especially in the turkey species.
The present study is therefore designed to test the survivability and fertility of turkey sperm stored under ambient temperature in different dilution media containing different types of metabolizable substrates including tropical coconut milk and citrus juice without antibiotics.
Objective of the study
This research project is designed to study the survivability of turkey sperm preserved in different diluents and to determine the fertility of ejaculates using different insemination doses.
The specific objectives of the study are:
- To determine the effect of different diluents on survivability of ejaculated turkey sperm.
- To determine the effect of insemination doses on fertility and hatchability of turkey eggs.
1.3 Justification of the study
Low fertility in turkeys, due to unsuccessful mating caused by large body size of the tom and reduced libido is a serious and costly problem in the production of hatching turkey eggs (Merck pub., 2008).
Burke (1984) observed that modern toms lack the coordination and dexterity to complete mating to assure high fertility. In most cases partial completion of mating act even without transfer of semen to the female results in variable periods of sexual refractoriness during which time hens normally will not remate.
Apart from this, lack of efficient storage or dilution media is a contributory factor since low number of spermatozoa from superior sires can be propagated if ejaculates are properly extended in good diluents. Similarly, lack of adequate knowledge on usage of natural substrates like orange juice, coconut milk and inclusion of antibiotics during semen preservation has added depletion value to semen storage as well as relegated genetic potentials of toms. These inadequacies have adversely affected poult production and economic viability of turkey industry.
In this country, different natural metabolizable substrates like orange juice, coconut milk, tomato juice are available at low cost to assist turkey farmers in preserving semen under ambient temperature. To save our turkey industry from collapse, efficient semen dilution and preservation technique must be employed to facilitate high fertility of turkey semen in the field. In the same vein, improvements leading to long-term storage of turkey semen are important especially now that the commercial production of domestic turkey rely almost entirely on artificial insemination.
The present study is aimed at facilitating effective large scale production of turkeys by artificial insemination to improve the low per capita protein intake in the country boost the economic viability of turkey farming.