Pig fattening : a survey of the effects of high levels of moist maize in the diet of growing-fattening pigs on the quality of fat tissues

Maize contains high levels of linoleic aicd C18:2 (17.8 g/kg of C18:2 at 86% DM). It has been established that the maximum amount of C18:2 in pig diets is 1.7% on a dry matter basis (14.8 g/kg at 87 % DM), in order to maintain the C18:2 level in fatty tissues lower than 15%, beyond which problems of technological quality of fat tissues can occur.A survey has been undertaken in 12 farms using between 65% and 77% of moist maize in pig diets, to evaluate the fatty acid composition of pig back fat and the C18:2 level in the maize.A total of 144 fat tissue samples, taken from 12 female pigs per farm (including 6 pigs showing a low back fat thickness), were analysed. The average C18:2 level in pig back fat was 11.8% and thus lower than the 15% threshold. In eight fat tissues samples, out of which 4 were from the same farm, the C18:2 was highter than 15%. In average, the stearic acid (C18 :0) content was of 14.8% and higher than the minimum threshold of 12%. Our study confirms that the proportion of maize in the diet, the pig back fat thickness, the lean meat content and the carcass eihgt influence the C18:2 level in pig fat tissues. Finally, this survey demonstrates that the use of 65% up to 77% of moist maize in the diet of fattening pig produces pig fat tissues that meet the requirements of pork industry.