Nutritional evaluation of dehulled and yellow seeded canola meals in poultry

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Simbaya, Joseph
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The study was conducted to evaluate the nutritive value of dehulled (DCM) (Brassica napus L, cv. Westar) and yellow seeded (YSM) (Brassica compestris L, cv. Parkland) canola meals in poultry. Meals of commercial (CCM) and brown seeded (BSM) (Brassia napus L, cv. Westar) canola were used as controls. The CCM and DCM were obtained from Can Amera Foods, Altona and POS Pilot plant, Saskatoon, respectively while those of BSM and YSM were prepared in the laboratory. Compared to the the other meals, DCM had significantly higher and lower levels of protein and glucosinolates, respectively while BSM was higher in the content of total dietary fibre (TDF) and neutral detergent fibre (NDF). The levels of non-starch polysaccharides (NSP) were highest and lowest in YSM and DCM, respectively. However, both meals had similar NDF values. The protein composition of amino acids were similar in all the meals apart from DCM which had slightly higher values. There were no major differences among meals when amino acids were evaluated as percentage of protein in the meal. A study with precision-fed cockerels showed true metabolizable energy (TMEn) values to be higher in DCM and CCM than in YSM and BSM which had similar levels. There was generally low NSP availability in all the meals and comparison among meals showed DCM to have a lower value than the other meals. True amino acid availabilities (TAAA) were slightly higher in DCM and CCM though there were no significant differences among meals. A one week digestibility study with intact and cecectomised laying hens fed semi-purified diets containing 45% canola meal indicated no major differences in the digestibility of lipids, energy, NSP and amino acids between intact and cecectomised hens. In contrast to the precision fed cockerel assay, the laying hen digestibility study showed BSM to have relatively better amino acid digestibilities than the other meals while YSM tended to have the lower values. Based on glucosinolate content and color of the meal, the data indicate that DCM was subjected to excessive heat treatment during processing which may have influenced nutrient availability in this meal. The results on a two week growth trial with one week old cockerels indicated no major differences between meals in supporting chick performance. However, there were trends to indicate CCM to be of better feeding quality than the other meals.