EVALUATION OF LOW GLUCOSINOLATE — LOW ERUCIC ACID RAPESEED MEALS AS PROTEIN SUPPLEMENTS FOR YOUNG GROWING PIGS, INCLUDING EFFECTS ON BLOOD SERUM CONSTITUENTS

Abstract

Forty-nine 4- to 5-wk-old pigs, averaging 7 kg in weight, were allotted to seven treatment groups. Rapeseed meals (RSM) from two cultivars of double-low (low glucosinolate-low erucic acid) Brassica napus rapeseed processed at one plant, one of the same cultivars processed at a second plant, and a low erucic acid B. campestris cv. Span were compared as partial or complete replacements (up to 22% of the diet) for soybean meal (SBM) in diets of starting–growing pigs. Overall results for feed intake, daily gain and efficiency of feed conversion indicated that RSM from a double-low cultivar (now licensed as Tower) may completely replace SBM in diets for starting–growing pigs with no depression in performance. Results from un unlicensed cultivar (1788) were inconsistent, with differences possibly associated with residual hexane in one sample of meal. Digestible energy and nitrogen, metabolizable energy and nitrogen retention did not differ between treatments. A profile of 14 blood serum constituents was obtained from individual pigs 3 and 9 wk after the start of the experiment. Thyroxine (T4) values were lower (P < 0.05) for all treatments when RSM was completely substituted for SBM. Protein-bound iodine values did not differ significantly between treatments but followed the same trends as T4. Results suggest that all RSM samples were goitrogenic to some degree. Blood serum constituents that correlated with average daily gain at [Formula: see text] were calcium, total protein, albumin, albumin:globulin ratio and lactate dehydrogenase. The results suggest that RSM from low glucosinolate–low erucic acid rapeseed, when it becomes commercially available, may be fed at higher levels than currently recommended.