Physiological response in rats consuming crude cowpea, Vigna unguiculata, grains as substitute for commercial soybean cake: Morphometry and histological analysis of the digestive organs

Abstract

Thirty-six Sprague-Dawley rats of 100 +/- 5 g liveweight were used according to a random block design with three replications. Six rats per treatment were used to study the effect of the intake of crude grains of Vigna unguicuhata (van INIFAT 93) as substitute for commercial soybean cake on the morphometry and histology of the main organs related to protein metabolism. Five levels of substitution (20, 40, 60, 80 and 100%) were studied from a basal diet of soybean-maize. There was no changes due to the treatments in the stomach, small intestine, large intestine and pancreas. Only a small decrease in absolute weight of liver and kidneys was found not in weight relative to liveweight or metabolic weight, which was explained by a decline in animal weight. Histologically, no differences were observed between treatments in the cuts from the duodenum, the jejunum, the ilcum and the kidneys. Some anomalies were reported in the cuts from the liver and the kidneys in the animals consuming more than 80% cowpea (congestion, hemorrhage and turbid tumefaction in the former and vacuolar degeneration and degenerative processes in the renal tubes). It is concluded that it is physiologically possible to substitute up to 60% the commercial soybean cake by meal of crude cowpea grains, without affecting the main organs related to protein metabolism in rats.