Effects of feeding different levels of cowpea (Vigna unguiculata) on gut morphology and faecal composition in weanling pigs

Author: M.O. Makinde, E. Umapathy, B.T. Akingbemi and K.T. Mandisodza
Year: 1996
Issue: 2
Volume: 26
Page: 42 - 46

The effects of feeding diets containing different levels of raw cowpea on the histomorphometry of the small intestine and faecal composition were investigated in weaned piglets. A total of 100 21-day-old weaners were divided into five equal groups and were assigned to one of the five following meals; 100% soyabean (T1); 25% cowpea (T2); 50% cowpea (T3); 75% cowpea (T4) and 100% cowpea (T5). There were five pens for each group and four piglets per pen. The feeding trial lasted 28 days. Anti-nutritional factor (ANF) assay of the feeds revealed a higher tannin content in the T4 and T5 groups. Live weight gain was lower in the T5 group, as compared to other groups. Those animals which were fed diets T1 to T4 had longer villi, larger villus area and greater villi perimeter than pigs fed T5 diet. Fresh faeces collected daily for up to seven days postweaning, were analysed for their pH and moisture content while osmolarity and the levels of electrolytes, glucose and protein were determined from their extracts. The faecal analysis revealed an increase in the moisture content and a decrease in osmolarity in the T1 and T5 groups. Glucose and electrolyte concentrations were highest in the faeces of T1, T2 and T3 animals. A transient and mild diarrhoea was observed in the T1 group. However, 100% raw cowpea feeding (T5) results in pathophysiological changes in gut morphology leading to impaired absorption of nutrients. ANFs in the raw cowpeas could account for the observed changes in gut morphology and faecal parameters. The diminished growth therefore may be due to reduced digestive and absorptive capacities as a result of intestinal mucosal changes. It is suggested that processing of cowpeas is essential in addition to reducing the percentage composition of cowpeas in the pig ration, if they are to be recommended as a suitable alternative to the soyabeans in stockfeed.

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