Vietnam is a tropical country located in Southeast Asia with a total area of 33.2 million hectares and a population of 84 million. There are 52 million farmers, and 67% of the total labour force is working in agriculture. The cultivated area is estimated to be about 11 million ha. The value of the agricultural output accounts for 25% of the GDP, and is made up of 77% of food crops, 20 % of livestock products (mainly pigs, cattle, poultry and goats) and 3% of other products (Vietnam National Statistics, 2004).
Sheep in Vietnam were originally introduced from India, Pakistan and Africa and were concentrated mainly in the Phan Rang area in the central semi-arid part of Vietnam. The breed in this area is commonly called the Phan Rang breed after the province and the sheep are kept with the purpose of producing meat only. There was not much interest in sheep production in Vietnam until 1996 when more than 60 sheep were moved from Phan Rang to the Goat and Rabbit Research Center in northern Vietnam. There were two main reasons related to this: Firstly, mutton was not a common meat in the food culture of the Vietnamese people, and secondly many people, even scientists, believed that sheep could not thrive in a humid climate. This situation had an effect on the distribution of sheep in different areas, and also on the number of sheep, that was low and not increasing. However, the sheep imported to the Goat and Rabbit Research Center adapted successfully to the environment and performed well. Also, in recent years, due to the ongoing problems with Avian flu, poultry production has become increasingly difficult for the farmers and more attention has therefore been paid to small ruminants e.g. sheep production, both by farmers and by government. The focus has been on breeding, nutrition, and disease prevention. Some programs and projects having an impact have been carried out with the support of the government. In the years of 2005 to 2008, The National Sheep Study Program administered by the Goat and Rabbit Research Center is collecting information on indigenous sheep, and this information is being used to develop sheep production in appropriate areas of Vietnam. Another study program, funded by Ninh Thuan Province, in order to classify appearance and productive characteristic of two ancestries of Phan Rang sheep breed (twist and fur) has been realised. It is clear that sheep production can play an important role in the improvement of the incomes of poor farmers and is contributing to poverty and hunger alleviation in Vietnam at present. The population of sheep in Vietnam has increased rapidly from around 3000 in 1996 to more than 21000 in 2002 (Mai, 2003) and 56800 in 2005 (Report of Bureau of Animal Husbandry, 2006). Sheep have also been introduced to other provinces such as Hatay and the Mekong Delta region.
One of the problems when trying to develop sheep production in Vietnam is to provide feed of sufficient quantity and quality all the year around. The feed resources for almost all sheep raised in Vietnam are natural resources and not cultivated feeds making the production unstable and of low efficiency. Using concentrate as supplement to increase sheep performance may, however, not be the best solution, because using concentrate is synonymous with daily cash investment and leads to high cost of the products.
Many studies have been conducted to identify biomass yields of forages and foliage of multipurpose trees to be used as feeds for small ruminants (Mui, 1994; Mui et al., 1997; Tien et al., 1997; Mui et al., 2001) in Vietnam and some have been evaluated and used successfully for goats (Mui et al., 2001; Mui et al., 2002; Van et al., 2002; Dung et al., 2003; Van et al., 2005). However, there is not much information on feeds for sheep.
Objectives:
The general objective of the study was to evaluate some protein rich forages as a replacement for a commercial concentrate in order to improve the performance of sheep and to reduce the price of the products.
The specific objectives were:
· To evaluate the effect of supplementing a basal diet of urea treated rice straw with Cassava, Stylosanthes or Jackfruit on intake, growth rate, digestibility and nitrogen retention of growing lambs.
· To study the effect of secondary compounds (mainly tannins) in the foliages on the number of parasite eggs in the sheep faeces.