Influence of diets containing raw or heat processed cowpea on the performance and gut health of broiler chickens

Abstract

An experiment was conducted to determine the influence of diets containing raw or heat processed cowpeas on the performance and gut health of broiler chickens. Forty eight day-old male broiler chicks were used in this study. The birds were randomly assigned to six mobile battery cages with eight birds per cage. The cages were assigned to three isonitrogenous and isocaloric diets in duplicate so that each treatment group had sixteen birds. The birds were fed for nine days on the following diets: T1 (control diet - corn-soy); T2 (20% of raw cowpea) and T3 (20% of roasted cowpea). The results showed no effect of either cowpea treatment versus control diet on weight gain, feed gain or cumulative period performance at day 5. However, by day 9, significantly higher weight gain was observed in chicks fed raw cowpeas compared to either roasted cowpeas or the control diet (P<0.05). Feed conversion and cumulative performance indices did not differ between groups fed the control diet or raw cowpeas, but chicks fed roasted cowpeas performed significantly poorer by day 9 (P<0.05). Although the raw cowpeas supported optimal growth in the chicks, histopathology indicated that the raw cowpeas were associated with inflammation of the duodenum. Gut morphology indicated that on day 5 duodenal crypt depth was significantly greater in birds fed on roasted cowpeas compared with the other two treatments. The differences between treatments in villus length, width, crypt depth, or muscle appearance were not apparent by day 9. Gastrointestinal viscosity was higher in the group fed T3 compared with T1 and T2. Although these results are contrary to expectations, there was no indication of over processing/ overcooking of the cowpeas that may have decreased protein quality. Data suggest that 20% of raw Mozambican cowpeas can be incorporated into broiler starter diets with no negative effects on growth or feed conversion.