High carotenoid maize is an ideal source of high value dietary carotenoids, especially lutein and zeaxanthin, in human and animal feed and has been proposed as a feedstock for high carotenoid egg production. A modified analytical method was demonstrated to have reliability, reproducibility, and improved run-time and separation of xanthophylls. This method was used to confirm the localization of carotenoids in endosperm and to determine the effects of drying and storage on carotenoid levels in maize grain. A preliminary trial using room temperature drying indicated that while carotenoid profiles remain stable during storage, carotenoid levels decrease significantly from initial levels between 3 and 6 months of storage, but then remain stable for another year. A more rigorous trial using three drying and storage regimes (freeze-drying and storage at -80 degrees C; room temperature drying and storage; 90 degrees C drying and room temperature storage) indicated that extreme caution is needed to maintain carotenoid levels in maize during handling and storage, but in situations where freeze-drying is not possible, high heat drying is no more detrimental than low heat drying.

Lutein and zeaxanthin are commonly referred to as the macular carotenoids, as they are localized to ocular tissues and their loss is associated with age-related macular degeneration. Thirty-four high-carotenoid (HiC) lines exhibiting uniquely high concentrations of carotenoids resulted from alíele mining of the Orange Flint race using traditional breeding techniques and visual selection for deep orange endosperm color. Total carotenoid concentrations of the HiC lines ranged from 50 to 101 pg g"^ dry weight (DW) with iutein and zeaxanthin concentrations as high as 66 and 65 pg g'' DW, respectively, levels higher than reported in previous germplasm surveys. The HiC lines fall into three classes based on the accumulation of the major carotenoid: "high-lutein," "high-zeaxanthin," and "balanced." Significant year effects were observed for carotenoid concentrations but not for profiles. During kernel development the pattern of carotenoid accumulation in the HiC lines did not appear to be different than in yellow corn belt dent lines. Collectively, the HiC lines represented only one yi haplotype, 10 unique haplotypes of IcyE, and two unique haplotypes at crtRBL Interestingly, previously identified diagnostic polymorphisms within IcyE did not appear to be useful in distinguishing between high-lutein and high-zeaxanthin HiC lines, and high .i-carotene levels were achieved despite the presence of a suboptimal crtRBi alíele. The HiC lines illustrate the utility of mining allelic variation from exotic sources coupled with the power of simple visual selection and the potential limitations of diagnostic polymorphisms.

Two experiments were carried out to measure effects of body condition at calving and different levels of feeding after calving on milk and subsequent reproduction.In experiment 1, which was conducted in two consecutive years, 162 cows (77 in year 1 and 85 in year 2) were group feed so as to reach a target body condition (condition scores ranging from 3-6) four weeks before calving. During the last four weeks before calving, all cows were managed so as to maintain their individual condition scores. At calving, cows in similar condition of similar breed and with similar previous milk production were allocated to high and low levels of feeding at pasture for the first five weeks of lactation. Mean pasture intakes were 13.0 and 7.0kg dry matter (DM)/cow.d in year 1 and 15.0 and 8.5 kg DM/cow.d in year 2In experiment 2, 40 cows were offered pasture and hay from 20 weeks before calving to achieve a body condition score of either 4 or 6 by two weeks before calving. During the first five weeks of lactation, cows were individually fed in stalls on freshly cut pasture at one of three levels of intake, 7 or 10 kg DM/cow.d or .In both experiments cows were grazed as one group from week 6 to 20 of lactation.Improved body condition at calving resulted in an extra 4.0, 11.0 and 7.4 kg milk fat per unit condition score over 20 weeks of lactation, for year 1 and 2 of experiment 1, and experiment 2, respectively. Cows in poorer condition partitioned a higher proportion of feed energy to liveweight at the expense of milk production than did the cows in better condition. However, increasing the plane of nutrition in early lactation resulted in higher levels of milk production and reduced the need for cows to mobilize bodyreserves. Improved body condition at calving had a positive effect on milk fat percentage, particularly in early lactation, but did not affect milk protein percentage. Input-output relations calculated from the experimental data showed that the benefit sf to improve body condition before calving was less than that of additional feeding after calvin changes in the condition of the cows were taken into consideration (25.8 vs 1 4.6 kg DM to yi kilogram of milkfat). Improvements in condition and feeding in early lactation reduced the anoestrus interval after calving by 5.7 d for each additional condition score at calving and 1. d for each additional kgDM/cow.d fed over weeks 1-5 of lactation. The input-output relations resented will enable farmers to assess the likely consequenes of changes in their feeding management in the crucial peripartum period with a greater degree of confidence than in the past.

Glyphosate-resistant populations ofConyza canadensishave been spreading at a rapid rate in Ontario, Canada, since first being documented in 2010. Determining the genetic relationship among existing Ontario populations is necessary to understand the spread and selection of the resistant biotypes. The objectives of this study were to: (1) characterize the genetic variation ofC. canadensisaccessions from the province of Ontario using simple sequence repeat (SSR) markers and (2) investigate the molecular mechanism (s) conferring resistance in these accessions. Ninety-eightC. canadensisaccessions were genotyped using 8 SSR markers. Germinable accessions were challenged with glyphosate to determine their dose response, and the sequences of 5-enolpyruvylshikimate-3-phosphate synthase genes 1 and 2 were obtained. Results indicate that a majority of glyphosate-resistant accessions from Ontario possessed a proline to serine substitution at position 106, which has previously been reported to confer glyphosate resistance in other crop and weed species. Accessions possessing this substitution demonstrated notably higher levels of resistance than non–target site resistant (NTSR) accessions from within or outside the growing region and were observed to form a subpopulation genetically distinct from geographically proximate glyphosate-susceptible and NTSR accessions. Although it is unclear whether other non–target site resistance mechanisms are contributing to the levels of resistance observed in target-site resistant accessions, these results indicate that, at a minimum, selection for Pro-106-Ser has occurred in addition to selection for non–target site resistance and has significantly enhanced the levels of resistance to glyphosate inC. canadensisaccessions from Ontario.

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