A FIVE-DECADE SYSTEMATIC REVIEW OF RESEARCH PROGRESS ON PRODUCTION AND MANAGEMENT OF SMALL RUMINANTS IN BANGLADESH

Abstract

Background: Small ruminant animals (SRA) have been associated with humans since their domestication are of world significance as socioeconomic animals providing products (meat, milk, wool, hair) that are in growing demand and sustainability of rural economics and many ecosystems with poverty elevation and food security in rural people in developing world including Bangladesh. People clearly want the benefit of SRA with the application of knowledge of science and technological research. Some research progress on production and management of SRA has been made during the past five decades in Bangladesh. However, such research information is often fragmented and not easily accessible, although these research findings are essential for further research and effective SRA development planning. Objective: This review aimed to improve the information based on various aspects of production and management of SRA by compiling and reviewing published research findings to identify constraints of their production for practical and sustainable solutions. Materials and Methods: A systematic literature of review of research articles on production and management of SRA published mainly in journals from 1968 to early 2021 of Bangladesh has been reviewed. A total of 332 inland research articles on these aspects supported with 19 foreign related articles have been reviewed and analyzed. Results: Bangladesh has approximately 26.435 million goats and 3.607 million sheep. Among goat population, 90% Black Bengal goat (BBG), 8.0% Jamunapari (JP) and 2.0% crossbred goats. Ten phenotypic coat color characteristics of BBG with high performance with solid black color goats documented. Sheep and goats are considered polyestrous species, and the average gestation length lasts for 150 days and give birth twice a year under good management and nutrition. Most of the smallholder farmers (80.5-95%) are raised their goats in semi-intensive system and 47% rural women are involved in goat rearing. Approximately 96% goat farmers and 60% sheep farmers used roadside grass and tree leaves and only 4.0% goat farmers used cultivated fodder whereas 40% sheep farmers used cultivated and road side grass to feed their sheep. Daily supplement of 100-300g concentrate to grazing SRA improved the growth and carcass gain, productive and reproductive performances. Castrated goats at eight weeks of age showed a much higher growth rate (76.33g/day) than un-castrated (62.72g/day) goats. The productive and reproductive performances of SRA have been reviewed and discussed. The BBG has excellent reproductive efficiency but its lower live weight and milk yield encouraged for crossbreeding with exotic bucks. The meat and milk yield traits of crossbred improved but reproductive efficiency decreased in comparison to BBG. Selection breeding of BBG not only increased live weight but also improved carcass value and preserves the indigenous genetic resources from extinction of unplanned breeding. Similarly, the crossbreds between native ewes  exotic rams resulted positive effect on wool quality and live weight but a negative effect on prolificacy and lambing interval. Almost all SRA farmers depended on natural breeding system with some research data on the uses of AI and more than 70% farmers are being faced breeding service shortages. Major advances in methods of semen collection and evaluation, evaluation of male fertility, cryopreservation of sperm and estrous cycle control have been reported in both the goat and sheep in Bangladesh. In addition, knowledge of ovulation control, timing of insemination, gamete biology has also been reported in inland literature. The average slaughtering age of BBG reported to be approximately 12 months whereas in native Bengal sheep has been suggested to be 6 to 9 with an average of 8 months to get maximum return. The major challenges for SRA production are breeds, poor management, inadequate feeds, breeding bucks and rams and high neonatal mortality (kids 25.2%) and lambs (12.4%) in Bangladesh. Conclusions: The SRA rearing as smallholder farmers managed mostly semi-intensive system and requires improved feeding, provision of veterinary medical services, financial assistance, improve natural breeding and/or AI services and extension services to encourage and enhance production of sheep and goat at rural levels in Bangladesh. An improvement in the performance of SRA would directly improve the diet and standard of living of rural smallholder farmers in Bangladesh. Keywords: Systematic review, Five decades, Small ruminants, Production, Management, Bangladesh