THE FEEDING VALUE OF TOWER RAPESEED FOR EARLY-WEANED PIGS II. EFFECTS OF SUPPLEMENTATION OF COOKED SEED WITH IODINATED CASEIN AND PEA PROTEIN CONCENTRATE

Abstract

Ninety-nine pigs, fed ad libitum from 6.8 to 14.0 kg liveweight, were used to examine the effects of including iodinated casein (44 mg/kg diet) in an early weaning diet containing 20% of a low glucosinolate, low erucic acid rapeseed (Brassica napus L. ’Tower’). The rapeseed (RS) was prepared commercially by flaking and then cooking, but the enzyme myrosinase was not completely inactivated. Iodinated casein supplementation significantly increased growth rate, feed efficiency, the blood circulating levels of thyroxine and protein-bound iodine but produced no significant effect on feed intake or blood cholesterol values. Iodinated casein largely prevented thyroid englargement and the thyroids appeared histologically normal. There were no effects due to iodinated casein on livers, hearts or kidneys. These results indicate that iodinated casein is beneficial for growth and thyroid function of young pigs between 6.8 and 14.0 kg liveweight fed diets containing 20% ground, cooked Tower rapeseed and in which myrosinase is not completely deactivated. A second experiment with 48 pigs fed four diets (control; RS and pea protein concentrate PPC; RS and rapeseed meal RSM, and PPC) resulted in superior growth on the control diet and poorest feed conversion on the PPC diet. The same level (18.9%) of PPC, fed with RS, resulted in better feed utilization.