NUTRITIVE VALUE OF MALTED SORGHUM SPROUT IN BROILER CHICKEN DIETS

CHAPTER ONE

1.0         INTRODUCTION

The poultry industry has suffered more than any other livestock industry as a result of inadequate supply and high cost of feed (Hill, 1989; Mtimuni, 1995; Leplaideur, 2004). Cereal grains constitute the major sources of energy in poultry diets in the tropics (Oluyemi and Roberts, 2000). However, maize has remained the chief energy source in compounded diets and constitutes about 50% of poultry ration (Ajaja et al., 2002). Pressure on maize, wheat and recently cassava has been on the increase worldwide with emphasis being placed on export and other diversified uses mostly in flour based foods and ethanol production as an alternative source of fuel (Doki, 2007; Thornton, 2007). According to Etuk (2008), these trends require serious diversification of energy and protein feedstuffs for poultry, because the availability of cheap and good quality protein and energy sources remain the single most important limiting factor in poultry production in Nigeria (Bawa et al., 2003; Abeke et al., 2008). The fact that feed alone accounts for 70–80% of the recurrent production input in intensive monogastric animal production makes the utilization of multiple feed ingredients expedient (Mtimuni, 1995; Marie-Agnés, 2004). Field observations in Nigeria revealed the inclusion of sorghum and possibly wheat in poultry and rabbit diets (Ojo et al., 2005a; Abubakar et al., 2006; Etuk and Ukaejiofo, 2007) as alternatives.

Sorghum bicolor (L) Moench is widely grown in the semi-arid and arid savannah regions of Nigeria. Maunder (2002) reported that sorghum is a traditional crop in Africa and Asia and an introduced or hybridized crop in the western hemisphere. Sorghum is the world’s fifth most important cereal and is grown in semi-arid regions of Africa being well adapted to the harsh climate and naturally resistant to many pests (Belton et al., 2003).

It benefits from an ability to tolerate drought, soil toxicities and temperature extremes effectively than other cereals. In terms of the nutritive value, cost and availability, sorghum grain is the next alternative to maize in poultry feed (Subramanian and Metta, 2000). Several varieties of sorghum have been developed and introduced in Nigeria (IAR, 1999). However, the diversity of chemical composition and anti-nutritional factors, mainly tannin resulting in variability in digestibility from 35 – 60% or more have been reported (Becker, 1992). Varieties of sorghum, climatic and soil conditions, fertilizer types are listed among the factors responsible for the variations in chemical composition of sorghum (Aduku, 1993; Tacon, 1995; Ngoka, 1997; Etuk and Ukaejiofo, 2007; Etuk, 2008). The usefulness of sorghum by-products has been reported world-wide (Mosimanyana and Kiflewahid, 1987; Mahabile et al., 1990; Dowling et al., 2003; Macedo and Aguilar, 2005; Nyannor et al., 2007). Some varieties of sorghum have phenols concentrated in the outer layers of the kernel which serves as natural source of antioxidants for foods (Awika et al., 2001). Taylor and Da Silva (2004) reported that sorghum bran could be a source of protein for industrial uses. Apart from serving as a staple food in Nigeria, sorghum grain is used for the production of beverages.

Malting of sorghum, like barley, involves steeping or soaking, germination, drying and curing in Kiln and polishing. The resultant malt extract is a useful inp ut in breweries and food processing companies where it is utilized for the manufacture of malt drinks, syrups, beverages, baby foods, microbiological media and other useful products. Malted sorghum sprout (MSS) is a by-product of sorghum malting. The separated roots and shoots which are left after malt extraction from the young germinating sorghum seedlings are collectively called sorghum sprout (Aletor et al., 1998). Malted sorghum sprout has a lot of prospect as a feed stuff of the livestock industry. It is rich in organic nitrogen (Ikediobi, 1989). Malted sorghum sprout contains (g/kg); 226 crude protein, 48 crude fibre, 33 ether extract, 16 ash, 522 nitrogen free extract and 16.26 MJ/kg DM gross energy (Aning et al., 1998). Aning et al. (1998) reported that magnesium was the most abundant mineral while potassium was the least in MSS. Among the trace minerals, Zinc is the most abundant while copper is the least. Sorghum sprout is reported to contain a considerable number of amino acids with low level of methionine, lysine and threonine (Aning et al., 1998).

The anti- nutritional factors in MSS are tannin and hydrogen cyanide (Omogbai and Ojeaburu, 2010). Van Buren and Robinson (1969) reported that tannins affect the growth of animals in three main ways: they have an astringent taste, which affects palatability and decreases feed consumption; they form complexes with proteins which reduce its digestibility and they act as enzyme inactivators. Processing of Malted sorghum sprout was shown to have no significant (P>0.05) effect on growth (Fanimo and Akinola, 2006) but inclusion of enzymes in feed have shown positive results in counteracting the effects of anti- nutritional factors. This study was conducted to determine inclusion level of malted sorghum sprout on its utilization by broiler chickens and subsequent effect of enzyme treatment.

1.3         Objectives

Objectives of the study were to;