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Effects of Rapeseed Meal Supplementation in Gestation Diets on Reproductive Performance and Thyroid Hormones in Sows
The utilization of rapeseed meal (RSM) has been limited as an ingredient for swine diet because it contains anti-nutritional factors such as glucosinolates (GSLs) and erucic acid. However, RSM has a competitive price and there is limited research to determine supplementation level. Therefore the aim of this study was to evaluate the effect of RSM levels in sow diet on reproductive performance, thyroid hormones of sows and performance of their progeny. A total of 55 mixed-parity (average = 3.82) sows (F1, Yorkshire x Landrace) with an initial body weight (BW) of 193 ± 1.22 kg were used in this trial and sows were allotted to 1 of 5 treatments based on BW and backfat thickness with 11 replicates in a completely randomized design. The experimental treatments were divided by dietary supplementation level of RSM (0%, 3%, 6%, 9% or 12%) in gestation diets, and sows were provided one diet without RSM during lactation. The content of GSLs in RSM was 16.6 umol∙g-1 (DM basis). Body weight, backfat thickness at 110 d of pregnancy and weaning to estrus interval after weaning were not affected by dietary RSM levels. Sows fed diets containing RSM had decreased litter and piglet weight at birth (P<0.05), but litter size, total born alive and weight gain of progeny were not affected by RSM supplementation. In addition, no difference was observed in average daily feed intake of sows among dietary treatments. Serum triiodothyronine (T3) concentration of sows at 110 d of pregnancy was affected by supplementation level of RSM, resulting in quadratic RSM level response (P<0.05). Serum thyroxine (T4) concentration was clearly higher (P<0.01), when sows were fed diets contained 12% RSM at 110 d of pregnancy. However, concentrations of serum T3 and T4 in lactating sows and their piglets were not affected by RSM supplementation. In summary, sows fed diets containing RSM had decreased litter weight at birth and increased serum concentrations of T3 and T4 prior to farrowing, but there were no detrimental effects on the growth performance of nursing pigs and BW, backfat thickness, and litter size of sows when up to 12% RSM was fed.
Keywords: Rapeseed Meal; Reproductive Performance; Sow; Triiodothyronine; Thyroxine