No abstract

Day-old Lohman broiler chicks (n = 120) were fed on five starting diets for 4 weeks in groups of 24 birds. The starting diets contained 0%, 9%, 18%, 27% and 36% sweet potato tuber as a replacement for maize. From the fifth week, the 120 birds were tested in groups of 30 on four finishing diets containing 0%, 15%, 30% and 45% sweet potato tuber as a replacement for maize. The carcass quality was significantly (p < 0.05) improved due to a significant (p < 0.05) reduction of abdominal fat in the birds fed on the 45% sweet potato finisher diets. However, the birds on the sweet potato diet continually passed wet droppings, resulting in a significant (p < 0.05) reduction in body weight and feed conversion efficiency. The optimum levels of inclusion of sweet potato in the diets were considered to be 27% and 30% for starting and finishing broiler chickens, respectively. Sweet potato diets may be a remedy for fatty broilers.

Sixty weanling Large White x Duroc pigs were allocated to five groups of 12 pigs per group and fed on one of five diets. The five diets comprised 0, 50% and 100% unboiled, sun-dried taro cocoyam cormels (Colocasia esculenta) and 50% and 100% boiled, sun-dried taro cocoyam cormels as replacements for maize. The levels of some antinutritional factors were also determined in both boiled and unboiled, sun-dried taro cocoyam. Boiling reduced (p < 0.05) the amounts of the antinutritional factors in the taro cocoyam cormels. There were no significant differences (p > 0.05) in feed intake, weight gain or feed efficiency between the diets containing boiled taro cocoyam cormels. However, for unboiled, sun-dried taro cocoyam cormels, there were significant differences (p < 0.05) in weight gain and feed efficiency, these being depressed at more than 50% replacement of maize. This may be due to the relatively high amounts of antinutritional factors in the unboiled, sun-dried taro cormels. Boiled taro cocoyam cormels were comparable to maize as an energy source in the diets of weanling pigs.

No abstract

One hundred and twenty-six point-of-lay birds were randomly alloted into six groups of 21 birds each and fed six diets containing 0%, 10%, 20%, 30%, 40% or 50% of Dioscorea alata meal as a replacement for maize, corresponding to 0%, 20%, 40%, 60%, 80% and 100% maize replacement. There were no significant differences (p > 0.05) in feed intake, egg weight or feed efficiency between the control diet and the test diets. However, the daily egg production per 100 birds (hen day production), differed significantly (p < 0.05) among the treatments. The birds on the control diet and diets with substitution rates of up to 80% laid significantly (p < 0.05) more eggs than those on the 100% substitution rate. This shows that D. alata can replace up to 80% of maize or constitute 40% of a laying chicken diet, provided the rations are isocaloric and isonitrogenous. For this to be achieved, more soybean and/or more fish scraps, and more palm oil are needed in the diets containing D. alata than in diets based on maize.