EVALUATION OF THE NUTRIENT CONSTITUENTS OF FRESH FORAGES AND FORMULATED DIETS
1.1 BACKGROUND INFORMATION
Ruminant animals are mainly dependent on forages as these are essential to maintain their health and production at various stages of their development and growth. In developed countries, sufficient grazing land is available so ruminants can get adequate amount of green grasses during grazing seasons and when it is not possible in other season they are supplied with silage and other high quality conserved forages. Conversely, green forages are not abundantly available in some developing countries, so ruminants are mainly supplied with low quality forages (LQF) like cereal straws. The longevity and production are adversely affected when ruminants are reared with poor quality forage. To get more production from these ruminants it is necessary to enhance the utilization of these low quality forages. It may be possible to increase the nutritive value of these low quality forages through either biological or chemical procedures (Chaudhry, 1998). During the last five decades many studies were done to improve the quality of these forages by using different biochemical treatments. But improving the quality of forages by using these treatments was not always successful. Supplementation is another tool to improve the quality of low quality forages by adding nutrients that otherwise are low in these forages (Khandaker et al., 1998; Muetzel et al., 2003; Chaudhry, 2008). Supplements increase the utilization of low quality forages, but the requirement for these supplements is more than their availability in many developing countries (Devendra and Sevilla, 2002).
The Nigerian livestock sector has been characterized by shortage in meat and other livestock products supply, hence this has led to a decline in animal protein intake in recent years, partly due to high cost of feeds and feedstuffs (Ekenyem, 2006). This high cost of feeds materials is as a result of the population for grains between man, livestock and industry (Tegbe et al., 1994), brought about by shortage in crop production to sustain both human and livestock (Ekenyem and onyeagoro, 2006). Ruminants depend solely on forages for their nutrient requirement in general and energy in particular, and forage have been reported to contribute about 75% of the dietary needs of ruminants (Das and Gosh, 2001). But the tropics is characterized with seasonal shortage in quantity and quality of forage from natural pasture, which continuously lead to low productivity in the livestock industry.
Historically, the term forage has meant only plant eaten by animal directly as pasture, crop residue or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animal especially as hay or silage (Karpouzi et al .,2006). Forage over the years have assisted ruminant farmers in achieving production targets, such as growth or weight gain in production, and also make up for seasonal shortfall between feed demand and supply. But the nutritional values of forage species are low in the dry seasons compared to the wet seasons (Buxton, 1996), and this seasonal variations affect the availability of nutrient, from the soil to forage to forage species (Ajayi, 2012). This is as a result of the dependence of forage nutrient contents on the amount of moisture found in the soil in which the forage plants grow McDowell et al., (1983) in forage plants are dependent upon the interaction of a number of factors which include plant species, soil type plant age, pasture management and climate and ruminant animals rely more essentially on forage for their nutrient requirement than any other feed resources.
Balanced diet is essential for normal physiological functions of ruminant animals (McDonald et al., 1995). It has also been shown that when balanced diet are fed to animals, their performance or productivity is enhanced and they are better equipped to fight diseases as a result of improved immune system (McDonald et al .,1995). In Nigeria, forage species still serve as a source of essential elements for grazing animals. Pennisetum purpureum also known Naiper grass or elephant grass are perennial grass in Poaceae family. It is an important fodder crop for livestock farmers because they have dry matter yield especially with frequent cutting (Farrel et al., 2002). Pennisetum purpureum grows in almost all the regions of Nigeria (Kallah, 1999). It grows under natural conditions and contributes excellently to livestock forage in great part of the year. Asaolu et al .,(2010) reported that native pastures such as pennisetum purpureum are the mostly widely available low cost feed for ruminants in the tropics, and are highly palatable to farm animals at leafy stage (Strezov et al .,2008). Pennisetum purpureum is a very important forage in the tropics due to its high productivity. It is particularly suited to feed livestock through cut and carry systems (zero grazing), fed in stalls, or made into silage or hay. Pennisetum purpureum can be grazed, provided it can be kept at the lush vegetative stage, because livestock tend to feed only the younger leaves (FAO, 2015).
The legumes are the third largest of flowering plants comprising of over 18000 species in 650 genera, which are well distributed in most environment throughout the world. Legumes have become important as high quality forage for livestock both in cultivated pasture and in natural occurring association (Brewbaker, 1986).They have high quality nutrient, higher digestibility and their nutrient value tends to remain higher et al as plant manures. Centrosema pubescens commonly known as centro or butter pea is a perennial herb in the family Fabaceae and originated in central and south America ,and it has been cultivated in both tropical and temperate areas as forage for livestock .It is a good source of protein, calcium and phosphorus to livestock. They are promising forage in regions looking for an alternative to enhance the protein content of livestock (Costa, 2009). Calopogonium mucunoides a genus of flowering plant in the legume family also serves as a source of feed to livestock. They are vigorous creeping twinning and hairy herbs that forms a tangle mass of foliage 30 to 40 cm deep and they are a good source of protein (Pizzaro,2001).The major contribution of C. mucunoids is to increase the crude protein content of animal diet and consequently increasing animal production both during dry period and wet season. Legumes are been fed to animals to yield increased growth rates (Arigbede et al., 2005). To maintain good health and proper growth rate, ruminants should be fed a balanced diet based on requirement defined by the National Research council (1981) and to reduce cost, forages such as hay, silage and pasture should constitute a majority of the daily diet, also supplementing the diet with grain mixes is important in order to provide additional energy and protein especially during lactation.
The concept of a complete diet comprising of forage and concentrates arose as a result of the shortfall in the productivity of dairy cows fed hopper. Owen, (1975) observed that allowing dairy cows continuous and simultaneous access to roughage and concentrates, but on separate hoppers led to inefficient over consumption of concentrate, leading to impaired rumen function and predisposition to digestive upset. So a mixed diet containing an optimum proportion of forage and concentrate according to production function of the ruminant is therefore an essential basis for sound feeding system. The study intends to investigate chemical composition and nutrient status of three forages Centrosema pubescens, Pennisetum purpureum, Calopogonium mucuniodes and concentrates mixture (Maize offal, Brewers Dried Grains, Molasses, Bone meal, salt).
1.2 OBJECTIVE OF THE STUDY
The general objective of this study is to determine the proximate composition of total diets comprising of forage-concentrate mixture in ruminant nutrition for improved ruminant production.
The specific objectives of this research work are:
. To determine the proximate composition of the forages
. To formulate and compound a total diet comprising the three forages (Pennisetum purpureum, Calopogomium mucunoides and Centrosema pubescens and concentrates.
. To determine the nutrient constituents of the total diets.
1.3 STATEMENT OF PROBLEM
Ruminants usually face feed scarcity during the dry season. Their natural grazing sites are being reduced due to urbanization and land fragmentation in Nigeria as a result of reduced productivity of our indigenous animals. Animal’s requirements for efficient production cannot be met without adequate intake of good quality feed at all times. The main source of these nutrients are forages, sourced from unimproved pastures in various areas this animals are kept, these source cannot guarantee all year round feed provision for efficient animal production. Conventional feedstuffs such as grains, groundnut cake, soya beans are very expensive and not readily available because man utilize them as food. This has increased cost of livestock production with the subsequent high cost of animal product such as meat, milk, and leather (Esonu et al., 2003).
Shortage of feed during the dry season, and sometimes during the wet season, put a constraint to livestock production in almost every production system in Nigeria. Where feeds are found in abundance, they may be low in nutritive value which may manifest themselves in form of nutritional deficiencies when fed to animals. However, in the tropics, the nutritive characteristics of forages fluctuate throughout the year. This is likely to result in an increase in cost of feeding and reduced profitability, as farmers revert to supplementary feeds to offset herbage deficit. Failure to supplement animal feeds leads to sharp decline in animal performance. Therefore optimum production responses from pasture regimes intimates’ knowledge of forage nutritive value combined with appropriate management strategies for its exploitation.
Nutrition is the most important consideration in ruminant animal production. Supply of feed in inadequate amount and quality is responsible to a large extent for low livestock productivity in the tropics. Ruminant animals depend solely on plants for their nutrient requirement in general and energy in particular, and forage have been reported to contribute about 75% of the dietary needs of ruminants. The feeding value of any forage is a function of characteristics of the species, such as its availability, acceptability, and nutrient availability. But during the dry season, ruminant diets are limited by shortages in amount and quality of available forage (Shelton, 2004). Crop residues or by products (Babayemi et al., 2004) which result in reduced livestock productivity in the tropical countries (Odenyo et al., 1997). Forages has always been a cheap source of animal feed but has poor nutrient profile especially during the dry season, so the feeding value of forages depends on the balance between available nutrient and quantity of nutrient ingested by the animals (Matlebyne, 2005). Through successful investigation forages can be preserved in raining season, either through hay or silage making and be utilized in dry season in order to improve livestock production all year round.