IMPACT OF SELENIUM FERTILIZATION ON GLUCOSINOLATE CONCENTRATION IN ARABIDOPSIS THALIANA AND RAPID CYCLING BRASSICA OLERACEA

Brassica vegetables are a significant source of glucosinolates (GSs), which are sulfur (S)-containing phytonutrients exhibiting, upon hydrolysis by endogenous myrosinase, antioxidant and anti-carcinogenic activity. Selenium (Se) is an essential micronutrient in mammalian health exhibiting antioxidant activity by inhibiting experimental carcinogenesis in animal models and reducing cancer incidence in human clinical trials. Selenium is readily accumulated in both Brassica species and Arabidopsis thaliana, a model species with similar S-metabolism. The research objectives for this project were to: 1) compare the impact of Se fertilization on GS concentrations between Arabidopsis thaliana and rapid cycling Brassica oleracea; and 2) determine the level of Se fertilization needed to optimize plant tissue Se concentration to maximize potential human health benefits. Both S and Se concentrations increased in A. thaliana and B. oleracea tissues in response to increasing Se treatments. Concentrations of glucoiberin, glucoraphanin, aliphatic, and total GS differed significantly between A. thaliana and B. oleracea. Data demonstrates that anti-carcinogenic GSs can be modified through changes in Se treatment concentrations, yet high levels of anti-carcinogenic GSs can be maintained while increasing Se concentration to 0.8 mg Se L^-1. Thus, it is feasible to increase Se to beneficial dietary levels without compromising GS concentrations.     

沙棘果实中的植物营养物及抗氧化作用

本文测定了沙棘果实在不同成熟期中抗坏血酸，类胡萝卜素，莰非醇，豕草花粉苷和总酚化合物的含量。抗坏血酸和豕草花粉苷的含量随着成熟时间的增加而减少，而莰非醇含量随着成熟时间的增加而增加。并对沙棘提取物对脂质过氧化反应的抑制和自由基清除作用进行了评价。     

Collard landraces are novel sources of glucoraphanin and other aliphatic glucosinolates

The glucosinolate make‐up of the edible parts of some Brassica oleracea L. crops has been investigated previously, but the leafy‐green collard (B. oleracea var. viridis) remains relatively unstudied on this topic. Due to this lack of information, a collection of US landraces was examined for glucosinolate content of leaves. The specific objectives of this examination were to compare levels of certain glucosinolates among the conserved collard landraces, identify any individuals with a distinct glucosinolate profile and determine the potential of collard as a target for chemoprotective‐based plant breeding. During winter 2010/2011, 81 collard landraces, four other viridis and four collard cultivars were evaluated in the field and harvested leaves were assayed for glucosinolates. In a subsequent study, 19 selected landraces plus the cultivars were included in a repeat trial in 2012/2013. Eighteen collard landraces contained relatively high levels of glucoraphanin in leaves in both years, and three (designated G 32575, G 32580, G 32586 in the US National Plant Germplasm System) were found to contain glucoraphanin in excess of 9.5 μmol/g DM. The examined landraces are rich sources of important aliphatic glucosinolates, previously thought to be most abundant in other B. oleracea vegetables.     

Mitigating rumen methane and enhancing fermentation using rambutan fruit peel powder and urea in lactating dairy cows

The experiment was designed to study the use of rambutan (Nephelium lappaceum) fruit peel powder (RP) with urea (U) supplementation on rumen fermentation, digestibility, methane (CH₄) production, milk production and composition in lactating dairy cows. Four Holstein crossbred lactating dairy cows, with starting liveweight of 450 ± 15 kg with 130 ± 10 DIM (days-in-milk), were randomly allocated to respective treatments: without supplementation (control; T1), supplementation of urea (U) at 90 g/hd/day (T2), supplementation of RP at 450 g/hd/day (T3) and supplementation of RPU (RP at 450 g/hd/day and U 90 g/hd/day) (T4), respectively, using a 4 × 4 Latin square design. The results showed that the U, RP and RPU supplementation did not change feed intakes (p > 0.05) and digestibilities of DM and OM were similar. However, digestibilities of CP and NDF were increased in the U and RPU groups (p < 0.05). Acetate production was decreased, while propionate production was dramatically increased (p < 0.05) in both the RP and RPU groups respectively. Notably, the ratio of C₂:C₃, protozoal population and CH₄ production was reduced in both the RP and RPU groups. In addition, nitrogen intake and nitrogen excretion were significantly higher while nitrogen retention was increased in the U and RPU groups. Allantoin excretion and absorption, microbial protein synthesis and efficiency of microbial N supply were increased in the U and RPU supplementation groups (p < 0.05). Furthermore, milk yield, milk fat and total solids were significantly enhanced in the U and RPU groups (p < 0.05). Moreover, the 3.5% FCM was increased (p < 0.05) while milk protein, lactose, solids-not-fat and milk urea nitrogen were not altered (p > 0.05). Supplementation of either U or RPU significantly improved fibre digestibilities, rumen fermentation, microbial protein synthesis, reduced protozoal population, mitigated CH₄ production and enhanced milk yield and milk composition.