Effect of active dry yeast on lactation performance, methane production, and ruminal fermentation patterns in early-lactating Holstein cows.

This study was conducted to examine the effect of active dry yeast (ADY) supplementation on lactation performance, ruminal fermentation patterns, and CH4 emissions and to determine an optimal ADY dose. Sixty Holstein dairy cows in early lactation (52 ± 1.2 DIM) were used in a randomized complete design. Cows were blocked by parity (2.1 ± 0.2), milk production (35 ± 4.6 kg/d), and body weight (642 ± 53 kg) and assigned to 1 of 4 treatments. Cows were fed ADY at doses of 0, 10, 20, or 30 g/d per head for 91 d, with 84 d for adaptation and 7 d for sampling. Although dry matter intake was not affected by ADY supplementation, the yield of actual milk, 4% fat-corrected milk, milk fat yield, and feed efficiency increased quadratically with increasing ADY supplementation. Yields of milk protein and lactose increased linearly with increasing ADY doses, whereas milk urea nitrogen concentration and somatic cell count decreased quadratically. Ruminal pH and ammonia concentration were not affected by ADY supplementation, whereas ruminal concentration of total volatile fatty acid increased quadratically. Digestibility of dry matter, organic matter, neutral detergent fiber, acid detergent fiber, nonfiber carbohydrate, and crude protein increased quadratically with increasing ADY supplementation. Supplementation of ADY did not affect blood concentration of total protein, triglyceride, aspartate aminotransferase, and alanine aminotransferase, whereas blood urea nitrogen, cholesterol, and nonesterified fatty acid concentrations decreased quadratically with increasing ADY supplementation. Methane production was not affected by ADY supplementation when expressed as grams per day or per kilogram of actual milk yield, dry matter intake, digested organic matter, and digested nonfiber carbohydrate, whereas a trend of linear and quadratic decrease of CH4 production was observed when expressed as grams per kilogram of fat-corrected milk and digested neutral detergent fiber. In conclusion, feeding ADY to early-lactating cows improved lactation performance by increasing nutrient digestibility. The optimal ADY dose should be 20 g/d per head.

Abscisic acid treatment alleviates cadmium toxicity in purple flowering stalk (Brassica campestris L. ssp. chinensis var. purpurea Hort.) seedlings.

The aim of this research was to investigate how exogenous abscisic acid (ABA) alleviates cadmium (Cd) toxicity in purple flowering stalk (Brassica campestris L. ssp. chinensis) and evaluate whether it could be a potential choice for phytoremediation. Purple flowering stalk seedlings were cultivated in a hydroponic system with Cd at various concentrations (0-100 µmol L-1) as controls and Cd plus ABA as the treatment in the growth media. The soluble proteins, chlorophyll contents and the activity of the antioxidant enzyme system were determined by previously established biochemical methods. The contents of soluble protein and chlorophyll, and the activities of superoxide dismutase (SOD, EC 1. 15.1.1), peroxidase (POD, EC 1.11.1.7), ascorbic peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.8.1.7) and superoxide anion (O2·-) increased with the increase of external Cd concentrations, and then decreased in both Cd and Cd+ABA treatments, with higher activities of enzymes but lower level of O2·- in Cd+ABA than those in Cdonly treatments. It indicated that a stress adaptation mechanism was employed at lower Cd concentrations. The contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), increased with the increase of Cd concentrations in the growth medium, with the highest levels in the treatment of 100 µmol L-1 Cd with lower levels in respective Cd+ABAtreatments than the Cd only treatmetns. Plants treated with 100 µmol L-1 Cd plus ABA showed a 60% decrease in Cd content in the leaves but a 259% increase in Cd content in the roots. In summary, exogenous ABA might alleviate Cd toxicity in purple flowering stalk mainly by reducing the reactive oxygen species (ROS) though activing the antioxidant enzyme system and accumulating more Cd in roots.

Oxalate accumulation and regulation is independent of glycolate oxidase in rice leaves.

Cellular oxalate, widely distributed in many plants, is implicated to play important roles in various functions and is also known to affect food qualities adversely in fruits and vegetables. How oxalate is regulated in plants is currently not well understood. Glycolate oxidase (GLO) has long been considered as an important player in oxalate accumulation in plants. To gain further insight into the biochemical and molecular mechanisms, the possible roles of GLO in the process were studied. Drastically different levels of oxalate could be achieved by treating rice with various nitrogen forms (nitrate versus ammonium). While nitrate stimulated oxalate accumulation, ammonium reduced its level. Such treatments resulted in similar pattern changes for some other related organic acids, such as glycolate, oxaloacetate, and malate. By feeding plants with exogenous glycolate it was possible almost completely to restore the ammonium-decreased oxalate level. Under the two treatments few differences were observed for GLO mRNA levels, protein levels, and in vitro activities. Both K(m) for glycolate/glyoxylate and K(i) for oxalate remained almost the same for GLO purified from either nitrate- or ammonium-fed leaves. A further in vivo study, with transgenic plants carrying an estradiol-inducible GLO antisense gene, showed that, while the estradiol-induced antisense expression remarkably reduced both GLO protein levels and activities, oxalate levels were not significantly altered in the estradiol-treated transgenic plants. Taken together, it is suggested that oxalate accumulation and regulation is independent of GLO in rice leaves.