CHAPTER ONE
INTRODUCTION
Sheep are important part of the global agricultural economy
and they play a major role in many local economies (Weaver, 2005). Njidda and
Kibon (2004) stated that sheep are multipurpose animals, but they are primarily
kept for the production of meat (mutton), and they account for about 11% of the
total meat supply in Nigeria. The authors further stated that the inclusion of
animals slaughtered in the rural areas outside the slaughter
houses would have made this figure higher. Afolayan (1996)
reported that Yankasa sheep is very popular among sheep farmers, most
especially in northern Nigeria. Their high productivity in terms of growth
performance and prolificacy are paramount to the farmer (Akpa et al., 2006).
Inadequate and poor quality of feed, especially during the long dry
season is one of the major factors militating against
livestock production in Nigeria. The seasonality of feed supply in northern
Nigeria has affected animal production adversely (FDLPCS, 1992).
According to Rumirez-Orduna et al. (2005), due to high cost,
most smallholder livestock farmers cannot afford to supplement the diet of
their animals with expensive feed ingredients. Production of livestock and
their productivity are far below the population’s requirement for animal
protein. This under-production and low productivity are attributed
mainly to inadequate year-round availability of feed and
water, coupled with poor management (Abbey et al., 2001). In the Savannah zone
of Nigeria the basal diets of most ruminants in the dry season is based on crop
residues and dry standing grasses, and most of these feed resources are
imbalanced in nutritional value and vary from year to year (Zemmelink, 1999).
The natural rangeland serves as the major sources of forages
for ruminants in Nigeria. Rangeland forages, however, decline in both quality
and quantity during the dry season, resulting in low productivity of animals.
Gamba (Andropogon gayanus) is a tropical grass which is widely distributed
throughout the savanna ecology of Nigeria and forms the bulk
of feed available to ruminants grazing on rangelands
(Fitzhugh, 1978). Gamba grass is usually established as permanent pasture in
most commercial ranches or smallholder farms. It can be cut as fresh feed or
conserved as hay. The crude protein content of gamba grass is moderate in young
growth (7 – 10%) but declines rapidly with maturity (2 – 5%)
(Leeuw, 1979; Agishi, 1985). Alli-Balogun (2010) reported
CP, NDF and ADF contents of gamba hay as 3.76, 76.4 and 56.2%, respectively.
Rice straw, like other cereal crop residues is a potential
source of energy for ruminants. However, its potential as an energy source is
limited because it is high in dietary fibre (>50%) and low in crude protein
(2 – 7%) and mineral contents (0.02 – 0.16%) (Sundstol and Owen, 1984; Jung et
al., 1993). One way in which, the low nutritive value of rice straws could be
improved, is through treatment with urea. In feeding trial strategies for
improving milk production by Ehoche (2002), urea treatment
of crop residues is acknowledged to improve nutritional value of crop residues
and other fibrous by-products and reduce feed cost and wastages with practical
application at the smallholder level in developing countries. The author
further stated that in the tropics, cereal crop residues such as maize,
sorghum, millet stover and rice straw were produced in large quantities and
could be used as ruminant livestock feeds. Akande (2001) reported that in
Nigeria, rice is cultivated in virtually all agro-ecological zones and the
residue (straw) can be obtained or purchased at relatively cheap or free of
charge from all rice farms. According to FAO (2012), Nigeria is the second
largest producer of rice in Africa after Egypt and the largest in West Africa.
FAO (2013) reported that Nigeria production of paddy rice was estimated at
4,700,000 tonnes. This gives rise to increase in rice straw output in the
country which could be harnessed for ruminant livestock feeding. It was also
reported by Parnich (1983) that, information on the utilization of rice straw
in the diets of sheep is scanty. The use of rice straws could help improve
ruminant livestock production, if its nutritive value is enhanced.