The need to produce food especially animal protein to feed the ever increasing human population is a major problem in developing countries. Livestock account for one third of Nigeria’s agricultural GDP, providing income, employment, food, fiber, manure and transport. They are also a major source of government revenue (Babatunde, 1998). Livestock especially ruminants, are the most efficient users of uncultivated land and can contribute substantially to crop production. Proteins are very essential for the continued existence of man and there is a strong agreement that animal protein products such as meat, egg and milk etc are very crucial to man. This is because of the ability of these products to furnish excellent balance of essential amino acids necessary for normal growth and development. The proteins of animal origin are good sources of lysine and sulphur amino acids, which are low in proteins of plant origin (Omole, 1991). The demand for animal protein in the tropics, for example, Nigeria has been on the increase because of the rise in human population within the region.
Intake of animal protein at present is 4.82g/head/day (Tewe, 1999) as against a minimum required 35g recommended by Food and Agricultural Organization (F.A.O.) (Tewe, 1999). In Europe the actual average consumptions is put at 45g/head/day and in North America it is 70g/head/day (Tewe, 1999). The task facing any animal scientist in Nigeria is to increase the production of livestock products to make animal products available to our people especially the rural populace.
Maynard and Loosli (2002), noted that it is important to recognize that ruminants increase the supply of food for humans by consuming materials that otherwise could contribute little or nothing to feeding people. These include forages from rangelands, plant by-products and crop residues from which humans are unable to derive any useful energy. Nutrition is by far the most important environmental factor affecting livestock production and feed cost represents 75% or more of the total cost of animal production (Cordiez et al., 2001). Good nutrition is required if healthy animals are to give maximum yield of meat and milk. Well nourished animals are better able to withstand the incidence of diseases which may claim up to 50% of the flock (Devandra, 2003).
Nutrition plays a major role in the overall production, health and wellbeing of sheep flock in particular and animals in general. This implies that sheep producers should consider nutrition management a top priority. According to Stevens (2009), nutrient requirement of sheep varies with difference in age, body weight and stage of production. Insufficient energy limits the performance of sheep probably more than other nutritional deficiencies. An energy deficiency may result from inadequate amount of feed or from feeds (generally forages) that do not contain enough protein to “unlock” the energy in the feedstuff. In sheep rations, the amount of protein is more important than quality of protein. Sheep are 26% more efficient than cattle in converting pastures and forages into marketable products (Outhouse et al., 2010). Thus, sheep becomes more attractive economically as grain production cost rises. Forages supply approximately 80% of the yearly nutrient requirement of sheep. During the grazing season sheep are able to meet other nutrient requirement from pasture, salt and mineral supplement. Practically, all tropical sheep are maintained on unimproved grazing. They are grazed extensively often together with cattle and/or goats and in some more arid areas they are sometimes grazed together with camels. Occasionally, they are tethered on the roadside or managed indoors and fed cut forage. The sheep grazes the pasture herbage down to the soil level aided by its split upper lip. Its daily capacity for food intake in relation to its size is smaller than that of goats and cattle. So it is more selective in its grazing habits. Sheep generally avoid coarser vegetation but exercise some control over established shrubs by nipping out the softer growing points.
In Nigeria as in most developing countries, the inadequate supply of feed to ruminant livestock is a major cause of low level of productivity in the animal industry. The rainfall seasonality and poor distribution pose serious forage management and animal feeding problems during the dry season (Hagger, 1998). This made it necessary to exploit the potentialities of bambara nut waste and brewers spent grain as dry season feed supplements for West African dwarf sheep. The result will help to alleviate the loss of weight of sheep during the dry season. According to Shaw and Colville (1999), the main problem of livestock improvement in Nigeria is not fundamentally for the geneticists, but for the animal nutritionists. They stated that the nutrition of the existing breeds of cattle, sheep and goats should first be put on a higher plane before the geneticist and animal breeders can either select from and/or improve on them. The majority of livestock in Nigeria with the exception of those on experimental stations and government farms are reared on low plane of nutrition.
1.2 STATEMENT OF PROBLEM
Under natural grazing, ruminants suffer serious seasonality in feed supply both in quality and quantity. The rainfall seasonality and poor distribution pose serious forage management and animal feeding problems during the dry season (Hagger, 1998). According to Obioha and Ndukwe (1992), there is a general decline in crude protein, ether extract and ash, and a progressive increase in crude fiber, N-free extract and dry matter content of forage from the onset of the dry season in early November to the first rain in March of the next season. The effect of this on the animal is a general set back in performance, and specifically, the loss of weight gained during the wet season. The seasonality of these conventional ruminant feed made it imperative to exploit alternative and cheap sources of feed for ruminants especially during dry season. Bambara nut waste is the portion discarded as waste after the processing of bambara nut. Brewers spent grain is the material that is remaining after grains have fermented during the beer making process.
The evaluation of feed used for the nutrition of domestic animals is of paramount importance. The potential value of a feed for supplying a particular nutrient can be determined by chemical analysis. The value of a feed does not depend entirely upon the amount of nutrient it contains but, more correctly upon the amount of nutrients the animal can digest and use. Digestibility of a feed is that proportion which is not excreted in the faeces and is therefore, assumed to be absorbed by the animal (McDonald et al., 2002).
1.3 OBJECTIVES OF THE STUDY
The research was aimed at determining the growth and physiological response of sheep fed forage with or without supplementary Bambara nut waste and Brewers spent grain.
The specific objectives of the study were as follows:
- To investigate the effects of dry season supplementation of bambara nut waste and dried brewers spent grain on growth performance of West African Dwarf sheep.
- To determine the cost implication of feeding bambara nut waste and brewers spent grain to West African Dwarf sheep.
- To determine the effect of grazing with or without supplementary bambara nut waste and dried brewers spent grain on the blood metabolites (blood plasma ammonia and urea) of West African Dwarf sheep.
- To determine the digestibility of bambara nut waste and dried brewers spent grain by growing West African Dwarf sheep.
1.4 JUSTIFICATION OF THE STUDY
Tropical pastures are known for rapid decline in nutritional quality and this decline is at the peak during the dry season. As a result, there is the need to exploit cheap sources of feedstuff which will be used as supplements during dry season. This will alleviate the loss of weight associated with the feeding of sheep during dry season. The availability of bambara nut waste and brewers spent grain justifies their choice in this research work. Bambara nut is processed into flour and prepared in the form of ‘okpa’ which remains a common protein meal consumed by the people of the Eastern Nigeria. Beer industries are springing up in many places these days. There is a gigantic plant at 9th mile corner of Enugu State of Eastern Nigeria and this assures the availability of Brewers spent grain all year round. The result of the work will assist in providing animal protein to feed the increasing population in the developing countries especially the rural populace.
Chemical composition alone of any feeding stuff is a very imperfect standard to judge its nutritive value. This made it necessary to determine the digestibility of Bambara nut waste and dried Brewers spent grain in order to ascertain their proximate composition vis-a-vis their nutritive value. The determination of blood plasma metabolites concentration will help to estimate the proportion of dietary nutrients utilizable by ruminants. Blood plasma ammonia, urea and amino acids among others are indicative of the nutritional status of the animals.