Nutritive value for broilers of meals derived from newly developed varieties of yellow-seeded canola

This study was conducted to determine the nutritive value of the meals derived from recently developed lines/varieties of canola. The samples included the yellow-seeded Brassica napus, B. juncea and B. rapa and the brown-seeded B. napus canola. Two commercial meals from yellow-seeded B. rapa and brown-seeded B. napus canola served as control samples. All samples were of canola quality and contained between 11.4 and 21.7 μmol g−1 of glucosinolate in the oil free meal. The evaluation involved chemical analyses of protein, amino acids, carbohydrates, dietary fibre, ash and ether extract, in vitro protein digestibility and true availability of energy (TMEn) and amino acids. The overall feeding quality was evaluated in a 2-week growth trial with 4-day-old broiler chickens. There were no major differences among the meals with regard to amino acid content when expressed in g per 16 g N. The levels of amino acids reflected quantitative differences in the content of protein which for yellow-seeded B. napus and B. juncea and brown-seeded B. napus canola approached or exceeded 460 g kg−1 DM. Dietary fibre content varied from 271 to 352 g kg−1 DM with the lowest value representing the yellow-seeded B. napus and the highest the commercial meal from brown-seeded B. napus canola. In vitro protein digestibility values showed minor differences among the samples. True digestibility of amino acids averaged 84.1% with only minor differences among the samples. True metabolizable energy content was highest in the yellow-seeded B. napus sample (9.71 MJ kg−1 DM). There were no differences in weight gain of broiler chickens fed the commercial or laboratory prepared B. rapa and the yellow- and brown-seeded B. napus meals. Chickens fed B. juncea meal showed significantly lower feed intake and body weight gain which appeared to be attributed to a relatively high content of aliphatic glucosinolates in this particular meal (i.e., 21.7 μmol/g DM). Birds fed the yellow-seeded B. napus canola showed the lowest feed to gain ratio which averaged 1.51 and differed significantly from that of 1.59 and 1.61 for the commercial yellow-seeded B. rapa and the laboratory prepared brown-seeded B. napus canola, respectively.