Cassava root peel as a replacement for maize in diets for growing pigs: effects on energy and nutrient digestibility, performance and carcass characteristics

Two experiments were conducted to evaluate cassava root peel (CRP) as diet component for fattening pigs. In the first experiment, ten male pigs were used to investigate the nutrient digestibility and the nutritive value of CRP as replacement for maize in the diet at 0 %, 30 %, 40 %, 50 % and 60 %, while supplementing free amino acids (fAA). During two experimental periods, faeces were quantitatively collected and analysed for chemical composition. In the second experiment, 40 pigs received the same diets as in Experiment 1, and daily feed intake and weekly weight changes were recorded. Four pigs per diet were slaughtered at 70 kg body weight to evaluate carcass traits. Digestibility of dry and organic matter, crude protein, acid detergent fibre and gross energy were depressed (p<0.05) at 60 % CRP; digestible energy content (MJ kg^(−1) DM) was 15.4 at 0 % CRP and 12.7 at 60 % CRP. In the second experiment, CRP inclusion had only a small impact on feed intake, weight gain and feed conversion ratio (p>0.05) as well as on the length of the small intestine and the Longissimus dorsi muscle area. The missing correlation of daily weight gain and feed-to-gain ratio up to a CRP inclusion of 40 % indicates that negative effects of CRP on pig growth can be avoided by respecting upper feeding limits. Hence, a combined use of CRP and fAA can reduce feeding costs for small-scale pig farmers in countries where this crop-by product is available in large amounts.

Utilisation of Giant African snail (Achatina fulica) meal as protein source by laying hens

A 12-week experiment was carried out to investigate the effects of substituting Giant African snail meal for fish meal in laying hens diet. Four diets were formulated to contain snail meal as replacement for fish meal at 0 (control), 33, 67 and 100%. A total of 120 Shaver Brown pullets aged 18 weeks were allocated to the dietary treatments in a randomised design. Each treatment consisted of three replicates and ten birds per replicate. Feed intake increased only for the 33% treatment as compared to the 67% replacement diet but did not differ from the other treatments. There were no significant treatment effects on egg performance parameters observed (egg production, egg weight, total egg mass, feed conversion ratio and percent shell). The overall feed cost of egg production reduced on the snail meal-based diets. The organoleptic evaluation of boiled eggs revealed no difference between the treatments. Based on these results it was concluded that total replacement of fish meal with cooked snail meat meal does not compromise laying performance or egg quality. The substitution is beneficial in terms of production cost reduction and the reduction of snails will have a beneficial impact especially where these snails are a serious agricultural pest. The manual collection and processing of snails can also become a source of rural income.