MATERIALS AND METHODS

Source and Processing of Cassava Peel
This study was conducted at the Ahmadu Bello University Farm, Zaria-Kaduna State, Nigeria. The cassava peels used in this study were collected from garri grating depots and heavily sun dried to about 10% moisture content. The peels were then grounded in to meal before incorporation into the experimental diets.

Experimental Animals
Twenty weaner pigs were used in this study. The experimental animals were obtained from 2 sows that farrowed about the same time and had the same level of management. The weaner pigs (Large White X Land race) were weaned the same day with an average initial live weight of 7.63±0.21 kg.

The pigs were randomly allotted to 5 dietary treatments on the basis of sex and initial live weights in a randomized block design. There were 4 pigs per treatment with each treatment comprising of 2 boars and 2 gilts. All the experimental animals were held individually in standard open sided concrete floor equipped with feeding and watering troughs. The composition and calculated analysis of the test diets are presented on Table 1.

CPM and maize were used as main energy sources in formulating 5 isonitrogenous test diets. The level of CPM and maize-soyabean were varied to determine the optimum level at which CPM could substitute for maize in weaner pig rations. The dietary treatments were:

Diet 1: A 20% CP basal maize-soyabean diet (control)
Diet 2: 14.22% CPM inclusion (replaces 25% of maize in the basal diet).
Diet 3: 28.44% CPM inclusion (replaces 50% of maize in the basal diet).
Diet 4: 42.65% CPM inclusion (replaces 75% of maize in the basal diet).
Diet 5: 56.87% CPM inclusion (replaces 100% of maize in the basal diet).

All the dietary treatments were balanced for minerals and vitamins as recommended by (AOAC., 1990).

Management of the Animals and Data Collection
The experimental animals were held in quarantine a week to the commencement of the experiment during which they were treated against intestinal and external parasite. The animals were all subjected to same feeding and management treatments and then allowed an adjustment period of seven days on their test diets. Thereafter they were weighed to mark the beginning of the experiment. Feed and water were provided ad libitum. Measures were also taken to prevent wastage. At the end of every week, performance data such as average daily gains and cost were computed.

Analytical Framework
At the end of the 42 days trial, the pigs from each treatment were evaluated on the basis of carcass and average live weight. Regression analysis was employed to analyze the effect of the various levels CPM on the performance parameters. The gross Margin analysis was employed to assess the profitability of the various dietary treatments. The Gross Margin analysis according to (Olukosi and Erhabour, 1988) is given by,

Table 1:	Experimental diets compositions

RESULTS AND DISCUSSIONS

The regressions between levels of inclusion of CPM and feed intake, weight gain and crude fibre digestibility were statistically significant at the 5% level (Table 2). There was an observed depression in feed intake as the level of CPM increased in the diets (Table 3). This could be attributed to the poor palatability of cassava peels compared to maize, the dustiness associated with the use of CPM (Oke, 1978; Muller and Nah, 1974; Amaefule et al., 2006) and the increase in the level of dietary cyanide with increase in the amount of feed consumed.

The weight gain pattern obtained from this study closely followed that of the feed intake. The final and daily weight gain results indicated a linear decrease as the level of CPM in diets rises (Table 3). The net effect of reduced feed intake coupled with low energy density as the level of CPM increased in the diets might probably be responsible for the depressed weight gain observed in pigs fed high levels of CPM diets. It is also likely that the high fibre content associated with increased levels of CPM in the diets contributed to the depressed weight gains.

The gross margins for the dietary treatments are 1923.80, 1904.10, 1906.00, 1773.00 and 1623.90 for diets 1, 2, 3, 4 and 5, respectively. The maize-soyabean basal (control) diet has the highest gross margin of 1923.80. This was followed by diet 3, 1906.00 and diet 5 had the least gross margin of 1623.90 (Table 4).

Table 2:	Regression equations relating the different CPM diets to the performance of the weaner pigs
X denotes levels of CPM, *significant at 5%, NSnot significant

Table 3:	Performance of weaner pigs fed CPM supplemented diets

Table 4:	Estimated average costs and returns for the dietary treatments

CONCLUSION

Though the maize-soyabean basal diet gave the best result in terms of weight gains and total revenue accrued than the experimental dietary treatments, a complete (100%) substitution of CPM for maize in the diets would lower the cost from 333.20 to 159.10 and still reward the farmer with a gross margin of 1623.90 for his efforts (Table 4). Where CPM is to be incorporated in pig diets, diet 3 option could be adopted since it gave the best economic experimental dietary result. However in the face of excess demand for maize and the high cost of conventional feed, the substitution of CPM for maize could be considered as it is quite economical. It will afford the farmer to be in business and still earn a reasonable reward for his labour rather than go out to business due to high feed cost and feed scarcity. Furthermore, cassava peels as a waste product constitute environmental nuisance. The large scale utilization would therefore help in recycling the waste.