Two trials were carried out to evaluate the effect of inclusion level of canola meal derived from Brassica (B.) napus and B. juncea on cattle performance and nutrient utilization. Trial 1 consisted of backgrounding (54 d) and finishing (153 d) phases. The control diet for the backgounding (BK) phase consisted of 39% barley silage, 30.4% barley grain, 22.8% brome grass hay and 7.8% supplement (DM). Treatments consisted of B. napus or B. juncea at 15 or 30% (DM) inclusion, replacing barley grain. The finishing control diet consisted of 88.3% barley grain, 4.4% barley silage and 7.3% supplement (DM). Treatments consisted of B. napus or B. juncea at 10 or 20% (DM) inclusion, replacing barley grain. During BK, dry matter intake (DMI), average daily gain (ADG), gain: feed (G:F) increased linearly (P < 0.01) as the level of inclusion of B. juncea meal increased. Cattle fed B. napus meal showed a quadratic response (P = 0.05) in DMI and linear increase (P = 0.02) in ADG with increasing inclusion. During finishing, DMI increased linearly (P = 0.05) for cattle fed B. juncea meal while a quadratic response (P = 0.02) was seen with B. napus meal. Feed efficiency and NEg content of the diet (P ≤ 0.02) decreased linearly with increasing inclusion of both meals. Trial 2 evaluated dietary rumen fermentation and total tract digestibility characteristics in a 5 x 5 Latin Square Design. Diets were similar to finishing phase of Trial 1. There was no effect of treatment on rumen pH, however a linear increase in acetate (P ≤ 0.01), ammonia (P < 0.01) and decrease (P < 0.01) in propionate was seen with both meal types. Crude protein and acid detergent fiber digestibility increased (P = 0.03) linearly with increasing inclusion of B. juncea meal. The results indicate that canola meal derived from B. napus and B. juncea is not suitable as a supplemental energy source replacing for barley grain in finishing diets but canola meal from B. juncea can be fed at levels up to 30% of the DM in backgrounding diets if priced appropriately.

The phytopathogenic fungus <i>Leptosphaeria maculans</i> can cause blackleg disease on crucifers, which results in significant yield losses. Fungal diseases involve interactions between pathogenic fungi and host plants. One aspect of these interactions is mediated by secondary metabolites produced by both fungi and host plants. Phytotoxins and elicitors as well as phytoanticipins and phytoalexins are metabolites produced by fungi and plants, respectively. This thesis describes and discusses the isolation, structure, biological activity and biosynthesis of the secondary metabolites produced by L. maculans.<p> The elicitor-toxin activity bioassay guided isolation of elicitors and phytotoxins produced by <i>L. maculans</i> in a chemically defined medium lead to the isolation of general elicitors, <i>sirodesmin PL</i> (165) and <i>deacetylsirodesmin PL</i> (166), and specific elicitors, <i>cerebrosides C</i> (14) and D (31) from minimum medium (MM) culture under standard conditions. The known phytotoxins sirodesmin PL (165) and deacetylsirodesmin PL (166) induced the production of <i>phytoalexin spirobrassinin</i> (122) in both resistant plant species (brown mustard, <i>Brassica juncea</i> cv. Cutlass) and susceptible plant species (canola, B. napus cv. Westar). A mixture of cerebrosides C (14) and D (31) induced the production of the phytoalexin rutalexin (127) in resistant plant species (brown mustard, B. juncea cv. Cutlass) but not in susceptible plant species (canola, B. napus cv. Westar). New metabolites leptomaculins A-E (267-269, 272 and 274) and deacetylleptomaculins C-E (270, 273 and 275) were isolated from elicitor-phytotoxin active fractions but did not display detectable elicitor activity or phytotoxicity after purification.<p> New metabolites maculansins A (299) and B (300), which were not detected in cultures of L. maculans incubated in MM, were isolated from cultures of <i>L. maculans</i> incubated in potato dextrose broth (PDB). Maculansins A (299) and B (300) displayed higher phytotoxicity on brown mustard than on canola and white mustard (<i>Sinapis alba cv. Ochre</i>) but did not elicit detectable production of phytoalexins in either brown mustard or canola. Metabolite 2,4-dihydroxy-3,6-dimethylbenzaldehyde (212) was produced in higher amount in cultures of L. maculans incubated in PDB than in MM and displayed strong inhibition effect on the root growth of brown mustard and canola. <i>L. maculans</i> incubated in MM amended with high concentration of NaCl produced a new metabolite, 8-hydroxynaphthalene-1-sulfate (293), and a known metabolite, bulgarein (294), which are likely involved in the self-protection. The potential intermediates involved in the biosynthesis of sirodesmin PL (165) were investigated using deuterium labeled precursors: [3,3-2H2]-L-tyrosine (251a), [3,3-2H2]O-prenyl-L-tyrosine (312a), E-[3,3,5,5,5-2H5]O-prenyl-L-tyrosine (312b), [5,5-2H2]phomamide (171a), [2,3,3-2H3]-L-serine (233d) and [5,5-2H2]cyclo-L-tyr-L-ser (252a). Intact incorporation of [5,5-2H2]phomamide (171a) into sirodesmin PL (165) suggested that leptomaculin D (272) and E (274), and deacetylleptomaculin D (273) and E (275) are not intermediates in the biosynthesis of sirodesmin PL (165). They are more likely the catabolic metabolites of sirodesmin PL (165). Phomamide (171), the intermediate in the biosynthetic pathway of sirodesmin PL (165), is likely biosynthesized by coupling of prenyl tyrosine (312) with serine (233) rather than prenylation of cyclo-L-tyr-L-ser (252). When [3,3-2H2]-L-tyrosine (251a), [3,3-2H2]O-prenyl-L-tyrosine (312a), and E-[3,3,5,5,5-2H5]O-prenyl-L-tyrosine (312b) were fed into cultures of L. maculans, a â proton exchange was detected by 1H NMR through intrinsic steric isotope effect, which occurs before the formation of phomamide (171). The biosynthesis and catabolism of sirodesmin PL (165) were proposed based on the results obtained in this work.

The phytopathogenic fungus <i>Leptosphaeria maculans</i> can cause blackleg disease on crucifers, which results in significant yield losses. Fungal diseases involve interactions between pathogenic fungi and host plants. One aspect of these interactions is mediated by secondary metabolites produced by both fungi and host plants. Phytotoxins and elicitors as well as phytoanticipins and phytoalexins are metabolites produced by fungi and plants, respectively. This thesis describes and discusses the isolation, structure, biological activity and biosynthesis of the secondary metabolites produced by L. maculans.<p> The elicitor-toxin activity bioassay guided isolation of elicitors and phytotoxins produced by <i>L. maculans</i> in a chemically defined medium lead to the isolation of general elicitors, <i>sirodesmin PL</i> (165) and <i>deacetylsirodesmin PL</i> (166), and specific elicitors, <i>cerebrosides C</i> (14) and D (31) from minimum medium (MM) culture under standard conditions. The known phytotoxins sirodesmin PL (165) and deacetylsirodesmin PL (166) induced the production of <i>phytoalexin spirobrassinin</i> (122) in both resistant plant species (brown mustard, <i>Brassica juncea</i> cv. Cutlass) and susceptible plant species (canola, B. napus cv. Westar). A mixture of cerebrosides C (14) and D (31) induced the production of the phytoalexin rutalexin (127) in resistant plant species (brown mustard, B. juncea cv. Cutlass) but not in susceptible plant species (canola, B. napus cv. Westar). New metabolites leptomaculins A-E (267-269, 272 and 274) and deacetylleptomaculins C-E (270, 273 and 275) were isolated from elicitor-phytotoxin active fractions but did not display detectable elicitor activity or phytotoxicity after purification.<p> New metabolites maculansins A (299) and B (300), which were not detected in cultures of L. maculans incubated in MM, were isolated from cultures of <i>L. maculans</i> incubated in potato dextrose broth (PDB). Maculansins A (299) and B (300) displayed higher phytotoxicity on brown mustard than on canola and white mustard (<i>Sinapis alba cv. Ochre</i>) but did not elicit detectable production of phytoalexins in either brown mustard or canola. Metabolite 2,4-dihydroxy-3,6-dimethylbenzaldehyde (212) was produced in higher amount in cultures of L. maculans incubated in PDB than in MM and displayed strong inhibition effect on the root growth of brown mustard and canola. <i>L. maculans</i> incubated in MM amended with high concentration of NaCl produced a new metabolite, 8-hydroxynaphthalene-1-sulfate (293), and a known metabolite, bulgarein (294), which are likely involved in the self-protection. The potential intermediates involved in the biosynthesis of sirodesmin PL (165) were investigated using deuterium labeled precursors: [3,3-2H2]-L-tyrosine (251a), [3,3-2H2]O-prenyl-L-tyrosine (312a), E-[3,3,5,5,5-2H5]O-prenyl-L-tyrosine (312b), [5,5-2H2]phomamide (171a), [2,3,3-2H3]-L-serine (233d) and [5,5-2H2]cyclo-L-tyr-L-ser (252a). Intact incorporation of [5,5-2H2]phomamide (171a) into sirodesmin PL (165) suggested that leptomaculin D (272) and E (274), and deacetylleptomaculin D (273) and E (275) are not intermediates in the biosynthesis of sirodesmin PL (165). They are more likely the catabolic metabolites of sirodesmin PL (165). Phomamide (171), the intermediate in the biosynthetic pathway of sirodesmin PL (165), is likely biosynthesized by coupling of prenyl tyrosine (312) with serine (233) rather than prenylation of cyclo-L-tyr-L-ser (252). When [3,3-2H2]-L-tyrosine (251a), [3,3-2H2]O-prenyl-L-tyrosine (312a), and E-[3,3,5,5,5-2H5]O-prenyl-L-tyrosine (312b) were fed into cultures of L. maculans, a â proton exchange was detected by 1H NMR through intrinsic steric isotope effect, which occurs before the formation of phomamide (171). The biosynthesis and catabolism of sirodesmin PL (165) were proposed based on the results obtained in this work.

No description available.