Effect of Supplementing Grazing N’dama Calves with Urea Treated Maize Stover and Centrosema pubescens

Maize stover consists of the leaves and stalks of maize plants left in a field after harvest and it makes up about half of the yield and is similar to straw. Ensiling maize stover with urea makes it a urea treated maize stover. Centrosema pubescens is a legume in the family Fabaceae, subfamily Faboideae and tribe Phaseolae. It is native to Central and South America and cultivated in other tropical areas as forage for livestock. An experiment was conducted to investigate the effects of urea treatment on chemical composition; feed intake, blood urea and ammonia of maize stover. The potential of such a stover for growth performance of calves were investigated using 8 N’dama calves of 5 to 8 months of age and an average initial live weight of 92.5 kg. The animals were divided into two groups each of which were individually fed to appetite on basal diets of either untreated maize stover and Centrosema pubescens (Diet T1) or 5 % urea treated maize stover and Centrosema pubescens (Diet T2) for 90 days. In addition all the calves were allowed free access to mineral/vitamin blocks and ample drinking water ad libitum. Urea treatment increased the crude protein (CP) content of maize stover in Diet T2 by 22.12% and also a highly significant difference (p<0.01) in the crude fibre (CF) content over the untreated stover in Diet T1. Besides, compared with the untreated stover, urea treatment brought an improvement of 28% in daily feed intake. These improvements in terms of chemical composition, daily feed intake and dry matter intake led to a highly significant (p<0.01) live weight gain of animals fed on the urea treated stover diet compared with those fed on the untreated stover diet. However, there was no significant difference (p>0.05) in blood urea levels but significant existed in feed cost/kg gain and linear body measurements between the animals fed on Diet T1 and those fed on Diet T2. Generally, with the added advantage of Diet T2 being more cost effective than Diet T1, feeding urea treated maize stover may be considered as one of the strategies that bring about an efficient utilization of crop residues for livestock feeding in Eastern part of Nigeria.However, its economic advantage over other alternatives must carefully be examined under the prevailing price conditions before it is implemented in an area. © 2015 Elixir All rights reserved. Elixir Agriculture 89 (2015) 37043-37048 Agriculture Available online at www.elixirpublishers. com (Elixir International Journal) Tele: +2348106482972 E-mail addresses: chiemelapeters@gmail.com © 2015 Elixir All rights reserved Egbu C.F et al./ Elixir Agriculture 89 (2015) 37043-37048 37044 chemical method (treating with Sodium hydroxide, wood ash, ammonia) and biological method (using fungi to degrade lignin in crop residue and using solid state fermentation system). Efforts to improve the nutritive value of the cereals residues through treatment with urea and other chemicals have not been very popular because technologies are often high for application by small holder subsistence farmers (Owen and Jayasuriya, 1989). Large quantities of crop residues produced on private and government farms in Nigeria are wasted year after year. Some are left to rot in the field, which may improve soil fertility but most are burned (Onyeonagu and Njoku, 2010). The abundant supply of crop residues and agro-industrial by-products at reasonable prices could enhance production and reduce cost of compounded feeds without adversely affecting the performance of the animals. Therefore, because of increases in human population and consequent high cost and demand for conventional feedstuffs such as groundnut cake and soya bean meal, it has become increasingly necessary that alternative feed ingredients are found to reduce the competition between, man and livestock (Iyeghe-Erakpotobor et al., 2002). There is evidence that livestock fed with crop residues and agroindustrial by-products could achieve substantial weight gains (O’Donovah, 1979). The trend has changed from the situation in which maize stovers were considered as waste and are now being converted to animal protein for human consumption (Singh et al., 2004 and Singh et al., 2011). Recently there has been growing policy recognition of the role of non-conventional feed resources in livestock production (FAO, 1999). All ruminants depend on crop residues and agro-industrial by-products which play a significant role in the nutrition of ruminant animals (Agarwal and Verma, 1983). There is very little information on the actual availability and usage of crop residues and agro-industrial by-products in the eastern part of Nigeria compared to the northern part (Onyeonagu and Njoku, 2010). Therefore, the objectives of this study were to determine the improvement in chemical composition, growth performances, economics of feeding and blood urea and ammonia levels of N’dama calves fed urea treatment of maize stover as compared with the untreated stover and Centrosema pubescens. Materials and Methods Location and Duration of Study The study was carried out in the Cattle unit of the Department of Animal Science Teaching and Research Farm, University of Nigeria, Nsukka. Nsukka lies on the geographical coordinates of 6 0 52 ’ 0 ” N, 7 0 23 ’ 0 ” E and on the altitude 447m above sea level (Offomata, 1975). The climate of the study area is typically tropical, with relative humidity ranging from 65-80% and mean daily temperature of 26.8 0 C (Agbagha, et al., 2000). The rainy season of Nsukka is between April to October and dry season between November to March with annual rainfall range of 1680-1700mm (Breinholt et al., 1981). The experiment lasted for 14 days adaptation and 90 days experimental periods. Feed Preparation Maize stover of an improved sweet variety (Zea mays) was collected from the Department of Crop Science Farm, University of Nigeria, Nsukka after the maize cobs had been harvested. The maize stover was allowed to dry in the sun at constant moisture level. Both the maize stover and the fresh leaves of Centrosema pubescens was chopped to 6-8mm, then the maize stover was treated with 5% urea (5kg urea dissolved in 50 litter of water for every 100kg of maize stover) and ensiled in 0.2mm thick polyethylene bags of dimensions 112 x 76cm for three weeks. The maize stover was thoroughly hand mixed so that the urea solution was uniformly mixed with the maize stover. 50% untreated maize stover plus 50% Centrosema pubescens served as the control Diet A while 50% treated maize stover plus 50% Centrosema pubescens served as the Diet B. Experimental Animals and Management Eight N’dama calves of about 8 months old were randomly allocated to two treatments with four calves per treatment. They were housed in individual compartment in the Cattle unit of the Department of Animal Science, University of Nigeria, Nsukka Teaching and Research Farm. Treatment one was fed Diet A while treatment two was fed Diet B in the morning before they are allowed to go about their normal grazing and after grazing they are returned back to their individual compartment to continue feeding on the experimental diets. All the calves were allowed free access to mineral/vitamin blocks and ample drinking water ad libitum. Cleaning of the compartments, removal and weighing of leftovers from previous day were done daily before supplying each day’s diet. The animals were weighed monthly. Parameters The daily feed intake and monthly body weight gain were measured using weighing balance. The feed conversion ratio and dry matter intake were calculated as follows: Feed conversion ratio: feed intake (kg)/Weight gain (kg) Dry matter intake (g/day): %dry matter/100 x feed intake Blood samples were also collected from the calves before and after the experiment to determine their blood urea and ammonia levels. The blood urea was determined by Randox kit as described by Weatherburn (1967). The proximate composition of the experimental diets was carried out using A.O. A.C (2000) methods. Statistical Analysis and Design The effects of dietary treatments on different parameters and means were analyzed using the Students T-test, for a completely randomized design with two treatments. Results and Discussion