FEEDING HIGH LEVELS OF RAPESEED MEAL TO PREGNANT GILTS

Abstract

Eleven crossbred gilts were allotted at random to two dietary treatments containing either 0% or 12% solvent-extracted rapeseed meal (RSM) of Chilean origin as the main source of supplemental protein in the diet. The RSM, of Brassica napus type, contained 4.1 mg isothiocyanates per g meal. The experiment, which covered the periods of pregnancy and lactation, was started immediately after mating and terminated 3 weeks after birth. Results indicated that gilts fed 12% RSM during pregnancy gained significantly less with the same feed allowance (2 kg per day) than the fish meal (FM) group. Total litter size and weight at birth were similar for both treatments. However, only 49% of the piglets were born alive from the gilts fed the 12% RSM diet; thyroid glands of live and stillborn piglets were markedly enlarged and symptoms of iodine deficiency were clearly manifested. Most pigs died within 72 hours after birth and four of the seven gilts lost their whole litter during this period. Of total pigs born to RSM-fed gilts only 13.4% survived to 3 weeks, although these individual pigs attained weaning weights similar to those of FM-fed gilts. It is concluded that RSM of the type fed when used as the main source of supplemental protein for gilts may result in a severe iodine deficiency syndrome in litters when non-iodized sodium chloride is used in the diet.