Fecundity Genes in Sheep and Goat for the Improvement of Livestock

Pakistan is endowed with a wide diversity of sheep and goat genetic resources, which form the backbone of its rural livelihood security systems. The purpose of small ruminant raising is to produce quality meat to fulfill the demand of meat consumption. At present, there are 61.5 million goats and 28.1 million sheep in Pakistan, together they account for over 616 thousand tones of mutton and 795 thousand tones of milk production annually in the country. Small ruminants rearing now faces a dilemma to produce more mutton and wool for the growing human population against the reality of shrinking grazing resources, which are creating a major constraint to the further growth of the sheep and goat population. In the present scenario the demand for meat in Pakistan has increased rapidly, and the emphasis has shifted from wool/hair towards mutton as the main produce from sheep and goat rearing. There is an acute shortage of meat for domestic needs, apart from the huge demand in the international market. The gap between demand and production of mutton could be bridged by augmenting the reproductive rate of low-producing sheep and goat breeds. The importance of small ruminants in general and high prolific animals in particular, is greatly increased in Pakistan due to ever increase in the population growth rate during the last decade. Low production and high demand have double the price of mutton in the last 7 years. Due to bird flu, there is severe crisis in poultry industry and the entire load is shifted to red meat. As a result the price of mutton went out of reach of poor or middle class community. In order to decrease the gap of demand and supply, there is dire need to work on small ruminants particularly in identifying genes responsible for more birth per conception and also in life time of the animal. Such kinds of studies have produced good results through better production of prolific breeds. It is an established fact that an animal producing twins or triplet contributes more than 1.5 times toward meat than the animals producing single offspring per lambing. Among the indigenous goat breeds, Teddy goats are more prolific than other breeds of goats found in Pakistan. Twining percentage in goat breeds is 56.4, 26.5, 27.5 and 22.5 in Taddy, Beetal, Nachi and Dera Din Pannah respectively, where as in some breeds of sheep, the twinning percentage in Rambouillet, Hissardale, and Awasi are 25.5, 24.5, and 18.25 respectively in Pakistan. However twinning percentage in Lohi sheep is 32.72%. In fat tailed sheep breeds Balochi and Rakhshani had the fertility rate as 70-75%. Increasing prolificacy (number of lambs born) in the commercial flock in the past was primarily limited. Selection can also play a part, but is considerably slower.

Research shows it will take 10 years or more to make, at best, only a 20% improvement in lambing percent. Today the Booroola (Fecundity gene) offers a new option that can allow the commercial producer to create a high level of prolificacy and still retain the important other traits desired in the flock. The term "Booroola" was taken from the name of the ranch in Australia where sheep carrying the single gene for prolificacy were first discovered.  Booroola was the first major gene to enhance ovulation rate. There are three genes have been expressed in the ovary of sheep.  The two genes Growth differential factors-9 (GDF-9) and Bone morphogenetic protein-15 (BMP-15) have made their sources in oocytes, the BMPR-1B receptor of BMP is expressed by granulosa cells and the oocytes from the early to the late antral follicle stages and to a slighter amount by theca layer of ovine and bovine antral follicles.  Genetics of prolificacy in sheep and goat emphasize the importance of main genes which have been made known to affect litter size and rate of ovulation through various mechanisms. Keeping in view the importance of prolificacy in sheep and goat, a research project was planned in university of Veterinary and Animal Sciences Lahore, Pakistan to identify the polymorphism, its association with fecundity and uncovering the nucleotide picture of fecundity genes (BMP15) in sheep and goat breeds of Pakistan. Research work was carried out under the supervision of Prof. Dr. Masroor Ellahi Babar at Molecular Biology and Genomics Lab, Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences Lahore Pakistan. This is the first report of the whole nucleotide of BMP15 gene in the sheep. A lot of work has been reported on these genes but total nucleotide picture in the sheep is not reported. Sequences of BMP15 gene from goat breeds of Pakistan has been submitted to the NCBI GenBank database libraries,USA under accession numbers JN655669 and JN655670. Sequences of same gene from Pakistani sheep breeds have also been submitted to the NCBI GenBank under accession # JN655671 and JN655672. Now this information is also available online (http://www.ncbi.nlm.nih.gov/ ).

In the research finding, various polymorphism, insertion and deletion of nucleotides in goat and sheep breeds of Pakistan were identified and associated with fecundity and secondly some novel polymorphism in Pakistani goat and sheep breeds were identified which are different from the goat and sheep breeds of the world. Theses novel polymorphism will be helpful to identify the region of the goat and sheep breeds of the world. Now it had made so easy to identify high prolific animals at an early stage of life because of the identification of molecular marker. It will result in fast vertical expansion of small ruminants to increase the mutton production and uplift the socio economic condition of small ruminant’s farmers in the country.