Poultry semen is highly concentrated, containing 4-6 billion spermatozoa /ml in cock and has a low volume. Diluents are essential for poultry semen:
i) increase semen volume
ii) Increase in number of birds that can be inseminated by per unit volume of semen
iii) uniformly distribute the spermatozoa in the diluent making artificial insemination (AI) easy in hens
iv) and to prolong the sperm survival for both short and long term preservation of semen in vitro.
Using the poultry semen diluent, the services of superior male can be used maximally by artificial insemination (AI) technique which is not possible under natural mating. Therefore, the ultimate goal of the diluent is to improve the reproductive efficiency of male and to reduce the cost of poultry production.
Suitable and simple CARI semen diluents was developed for some poultry species ( layer, broiler, desi chicken, turkey, duck and guinea fowl).
Commonly available chicken semen extenders (dilutors) are complex in composition, need the adjustment of pH and osmotic pressure, thereby taking more time in preparation, and are expensive.
Owing to these problems, such dilutors are not feasible under the field conditions. Keeping in view these problems, a diluent was developed, which successfully preserves chicken semen at low temperature for 24 hr and does not require the adjustment of pH and osmotic pressure. Semen–diluent ratio can be kept 1:2 to 1:3 depending upon the number of spermatozoa in freshly ejaculated semen and duration of storage. This semen diluent gives very good fertility (above 80 %) even after 24 hr of storage at low temperature under test conditions and its fertilising ability is comparable to the freshly ejaculated semen of chicken. CARI poultry semen diluent was tested in more than 2000 birds in the institute and studies indicated that this diluent even works well up to 48 hrs. Large scale studies on this aspect are in progress.
As per our estimate if a broiler is donating nearly 0.5ml semen (sperm conc. 5.34 billion/ml) it can be inseminated into 110 hens/ male after dilution with CARI diluent (1:10) having 24 million sperm /dose of AI (0.05ml diluted semen). Nearly 90 % fertility can be achieved using freshly diluted semen. Comparable fertility can be obtained using 24/ 48 hr. stored semen in which nearly 30 hens /male can be inseminated with a per hen dose of 0.05ml diluted (1:2) semen containing nearly 89 million sperm. This study indicated that CARI poultry semen diluent is highly economical for poultry production.
(Source: ICAR-Central Avian Research Institute, Izatnagar)