Effect of replacing dried brewer's grain with 'sorghum rootlets' on growth, nutrient utilisation and some blood constituents in the rat

Sorghum rootlets (SR), a novel feed resource, and a byproduct of sorghum malting, was characterised with respect to the proximate, mineral, energy and amino acid profile. Thirty six (36) weanling rats were subsequently used to compare the nutritive value with that of brewer's dried grain (BDG) in a 2 X 3 factorial experiment combining the two ingredients at three levels: 100, 200 and 300 g kg(-1). The six trial diets were fed to the rats for a 28-day period. The results showed that the crude protein, crude fibre, gross energy (GE) and hydrocyanic acid (HCN) content of SR averaged 242.0 +/- 41.0 g kg(-1) are 64.0 +/- 14.0 g kg(-1), 3880 kcal kg(-1) and 225 mg kg(-1), respectively. Of the major minerals analysed, Mg was the most abundant (12.0 g kg(-1)) while P was the least (1.0 g kg(-1)). Among the trace minerals, Zn was the most abundant (150 mg kg(-1)) while Cu was the least (10 mg kg(-1)). The amino acids varied from 0.17 g(100 g)(-1) methionine to 1.16 g(100 g)(-1) glutamic acid. Rats fed BDG diets had better (P < 0.05) average daily weight gain, feed intake, feed conversion ratio, protein efficiency ratio, and nitrogen retention than the SR-fed groups. Haematological indices were unaffected (P > 0.05) by the sources or levels of inclusion of the test ingredients except, the white blood cell counts (WBC) which was higher (P < 0.05) in the BDG-fed rats. Serum aspartate aminotransferase (AST; EC 2.6.1.1) activities were generally unaffected, but alanine aminotransferase (ALT; EC 2.6.1.2) activities increased progressively (P < 0.05) with SR levels. Liver weights were bigger (P < 0.05) and kidneys smaller P < 0.05) in rats fed SR. The results suggest that SR is nutritionally inferior to BDG. (C) 1998 Elsevier Science B.V.