Improved productivity, profitability and sustainability of sheep production in Maharashtra, India through genetically enhanced prolificacy, growth and parasite resistance

• Nimbkar Agricultural Research Institute, India
• National Chemical Laboratory, India
• University of Melbourne, Australia

A high priority of the state and national Governments of India is to increase production of sheep meat and other livestock products to meet the growing demand for meat by the Indian population. Another priority is to increase supply of meat at reasonable prices in the rural, less affluent sections of society. This project aimed to consolidate and field-test, under shepherd management, the improved reproductive rate and parasite resistance of Deccani sheep, derived through earlier ACIAR-funded research by introducing genes from other Indian breeds.
A major finding of the earlier project was that the Australian Booroola fecundity (prolific) gene seems to have originated in the Garole sheep from the Sundabans in eastern India. The Garole also has considerable resistance to Haemonchus contortus, the predominant parasite of sheep in India and Australia. Specifically the project objectives were: a) to develop and multiply at NARI promising sheep genotypes for testing in shepherds' flocks; b) test their performance in shepherds' flocks in the Phaltan region, and to develop appropriate management technologies; c) to investigate the regulation of expression of FecB in Indian and Australian breeds of sheep; d) to develop extension and genetic models for the dissemination of proven genotypes within and beyond the local project area.

This project, with extensions, ran from 2003 to 2008 and involved collaboration between three lead institutions: the Nimbkar Agricultural Research Institute (NARI - an NGO in Phaltanin rural Maharashtra), the National Chemical Laboratory (NCL - a CSIR institute in Pune, Maharashtra) and the University of New England (UNE - Armidale, NSW Australia). The main thrust of the project was to test, under normal shepherding conditions, the performance of improved genotypes carrying the FecB (fecundity) mutation, and based on the results to develop recommendations regarding the wider dissemination of the gene.
The project team successfully implemented a complex breeding program at NARI, based on artificial insemination, full pedigree recording, determination of estimated breeding values and mate selection based on TGRM software. The program was designed to allow valid breed and FecB genotype comparisons.
The scientists genotyped the animals for FecB at a young age, using a DNA test to identify those carrying no copy of the gene (WW), one copy (BW) or two copies (BB). At the end of the project there were 45 BB rams and 123 BB ewes and 35 BW rams and 322 BW ewes at NARI. Distribution of FecB carrier ewes, rams and semen to 26 participating shepherds' flocks commenced in 2003 and by the end of the project these flocks contained 13 BB and 240 BW adult ewes. Although shepherds exhibited resistance to the undesirable features of the Garole breed in first-cross progeny with the Deccani, backcrossed ewes and rams (25% Garole or less) had greater acceptability.
One copy of the FecB gene was shown to increase litter size from 1.03 to 1.58 in the NARI flock and from 1.03 to 1.35 in the shepherds' flocks, a moderate and manageable increase. Two copies of the FecB gene increased litter size to 1.65 at NARI, a similar increase to that seen with one copy. By sale age of 3 months surviving litter sizes at NARI and smallholders respectively were 0.95 each for WW ewes, 1.35 and 1.21 for BW ewes and 1.34 for BB ewes (NARI only).
Overall BW ewes produced 27% greater weight of 3-month lamb than non-carriers, and twin-bearing ewes produced 42% more. Economic analysis revealed that twin bearing ewes had a gross margin 30% greater than that of single bearing ewes.
In commercial Merino sheep in Australia, FecB conferred higher increases in litter size than in India, but under Australia's extensive management system lamb mortality limited the utility of FecB carrier ewes. While the heterozygote exhibited superior overall productivity, homozygous ewes had significantly depressed fertility and lamb survival. This homozygote problem has not been seen to date in India, but will need to be monitored.
In India it is recommended that wider introgression of the FecB gene continue. To maximise the success of introgression, FecB-carrier animals for dissemination into local flocks should have a phenotype similar to the local breed and be selected and superior for other economically important traits. As introgression is a process requiring at least three generations of backcrossing, it will need excellent institutional infrastructure including a network and extension program among local sheep owners.
The project concluded with a successful 'International workshop on using the FecB gene in sheep-breeding programs', and the workshop proceedings are published as No. 133 in the ACIAR Proceedings Series.