Powdered maize cobs were tested as an alternative for pesticide use in stored maize. Five doses (2, 4, 6, 8 and 10 g/250 g seed) of powdered maize cobs applied at particle sizes of 1.4 and 0.4 mm diameter were compared with actellic powder against Sitophilus zeamais Motschulsky for 120 days. Mortality and survival data showed that cob powders did not act as fumigant but exerted a potent inhibition of progeny on direct contact with S. zeamais adults. The particle size of powdered cobs had no effect on maize damage and losses. At doses equal to or higher than 6 g powdered maize cobs/250 g grain maize, i.e. 2.4% (w/w), damage to grain was < 5% and weight losses < 1%. The protection offered at the highest dose was comparable to the pesticide control. The use of powdered maize cobs is discussed as a natural alternative to synthetic pesticides for protection of maize against S. zeamais.

A study was conducted to compare the performance of Mukota, Large White (LW) and LW ✕ Mukota F1 pigs given increasing levels of maize cob meal. Sixteen female weaners of each genotype were given, ad libitum, diets containing 0, 100, 200 and 300 g maize cob meal per kg of diet for 14 weeks. The diets were designed to contain similar levels of protein (ca. 160 g crude protein per kg) and energy (ca. 9 MJ metabolizable energy per kg). Average daily food intake per unit metabolic body weight (ADFI per kg M0·75), average daily gain (ADG) and food conversion ratio (FCR) were determined. The pigs were slaughtered and cold dressed mass (CDM) and backfat thickness were determined for each pig. The ADFI per kg M0·75 was similar among the four diets for the three genotypes. The rate of decline in ADG was higher (P < 0·05) in the LW than in the other two genotypes. The FCR in the Mukota was poorer (P < 0·05) than that in the LW and the F1 crosses. The Mukota had the highest (P < 0·05) backfat thickness (K5 and K7·5) values of the three genotypes across the four diets, followed by the F1 crosses. The CDM values for the LW and the F1 crosses were similar and were higher (P < 0·05) than those for the Mukota. The findings indicate that F1 crosses and the Mukota were better able to utilize diets containing high levels of maize cob meal than LW pigs.

A study was conducted to compare the digestibility of organic matter (OM), neutral-detergent fibre (NDF), acid-detergent fibre (ADF), hemicellulose and nitrogen (N) and N balance in Mukota (M), Large White (LW) and the LW × M F1 pigs. Four male pigs of each breed, at proportionately 0·3 of their mature body weights, were randomly allocated to each of four diets in a cross-over design. The diets, which were formulated to contain similar levels of protein (ca. 160 g crude protein per kg) and energy (ca. 9 MJ metabolizable energy per kg), contained 0, 100, 200 and 300 g maize cob meal per kg, which corresponded to NDF levels of 276·4, 360·3, 402·9 and 523·5 g/kg dry matter, respectively. There was a negative correlation (P < 0·001) between the digestibility of OM, NDF, ADF and hemicellulose and the level of NDF in the diet. The digestibility of OM, NDF, ADF and hemicellulose decreased linearly (P < 0·05) with increase in the level of NDF among all three genotypes. There was a genotype × diet interaction on NDF and ADF digestibilities with digestibility in the LW decreasing faster (P < 0·05) than in the Mukota and LW × M F1 cross with increasing NDF. Both breed and level of maize cob meal affected N digestibility (P < 0·001), whilst the N retained per unit metabolic body weight was only affected by diet (P < 0·01). Increasing the level of maize cob meal beyond 100 g/kg, however, did not reduce N digestibility (P < 0·05). There was neither genotype nor dietary effect (P > 0·05) on N retained per unit N intake. These findings showed that the Mukota and the LW × M F1 cross were better able to digest the fibrous components than the LW. In addition, the Mukota and the LW × M F1 cross displayed an ability to retain protein to the same extent as the LW.