Shifts in Rumen Fermentation and Microbiota Are Associated with Dissolved Ruminal Hydrogen Concentrations in Lactating Dairy Cows Fed Different Types of Carbohydrates.

BACKGROUND: Different carbohydrates ingested greatly influence rumen fermentation and microbiota and gaseous methane emissions. Dissolved hydrogen concentration is related to rumen fermentation and methane production. OBJECTIVES: We tested the hypothesis that carbohydrates ingested greatly alter the rumen environment in dairy cows, and that dissolved hydrogen concentration is associated with these changes in rumen fermentation and microbiota. METHODS: Twenty-eight lactating Chinese Holstein dairy cows [aged 4-5 y, body weight 480 ± 37 kg (mean ± SD)] were used in a randomized complete block design to investigate effects of 4 diets differing in forage content (45% compared with 35%) and source (rice straw compared with a mixture of rice straw and corn silage) on feed intake, rumen fermentation, and microbial populations. RESULTS: Feed intake (10.7-12.6 kg/d) and fiber degradation (0.584-0.692) greatly differed (P ≤ 0.05) between cows fed the 4 diets, leading to large differences (P ≤ 0.05) in gaseous methane yield (27.2-37.3 g/kg organic matter digested), dissolved hydrogen (0.258-1.64 µmol/L), rumen fermentation products, and microbiota. Ruminal dissolved hydrogen was negatively correlated (r < -0.40; P < 0.05) with molar proportion of acetate, numbers of fungi, abundance of Fibrobacter succinogenes, and methane yield, but positively correlated (r > 0.40; P < 0.05) with molar proportions of propionate and n-butyrate, numbers of methanogens, and abundance of Selenomonas ruminantium and Prevotella spp. Ruminal dissolved hydrogen was positively correlated (r = 0.93; P < 0.001) with Gibbs free energy changes of reactions producing greater acetate and hydrogen, but not correlated with those reactions producing more propionate without hydrogen. CONCLUSIONS: Changes in fermentation pathways from acetate toward propionate production and in microbiota from fibrolytic toward amylolytic species were closely associated with ruminal dissolved hydrogen in lactating dairy cows. An unresolved paradox was that greater dissolved hydrogen was associated with greater numbers of methanogens but with lower gaseous methane emissions.

[Effects of carbaryl production exposure on the sperm and semen quality of occupational male workers].

OBJECTIVE: To analyse the male reproductive toxicity of carbaryl. METHODS: Thirty-one male carbaryl exposure workers and 46 male administrators in the office in a pesticide factory were selected as the exposure group and internal control group respectively, and 22 male administrators in a center for disease control and prevention were served as the external control group. In order to evaluate the exposure levels, the concentrations of carbaryl, methyl isocyanate, ammonia and phenol in the ambient air of the work place in these three groups were monitored simultaneously for three consecutive days. Moreover, three workers in the exposure group and the external control group were selected to evaluate the amount of carbaryl of individual and dermal contamination for three consecutive days. After the semen were collected according to the standard method, the workers'semen qualities were analysed with WHO method, the sperm morphology and the sperm motility were evaluated using micro-cell slide spectrum technology and computer assisted sperm analysis (CASA) respectively. RESULTS: In the exposure group, the concentrations of carbaryl and phenol (52.41 mg/m(3) and 0.08 mg/m(3) respectively) were significantly higher than those in the internal and external control group (P < 0.01 or P < 0.05). Furthermore, in the carbaryl exposure area the geometric mean concentration of carbaryl with the individual sampling was 7.38 mg/m(3), and the geometric mean of dermal contamination detected in the carbaryl exposure area was 862.47 mg/m(2). Carbaryl was not found in the external control area (P < 0.01). The seminal volume [(2.39 +/- 1.44) ml] and the sperm motility [(1.77 +/- 0.61) grade] were significantly lower than those in the external control group (P < 0.05), and sperm motion parameters such as linearity (LIN, 39.89% +/- 6.00%), straightness (STR, 71.51% +/- 11.22%), straight line velocity [VSL, (26.29 +/- 7.84) microm/s] and beat cross frequency [BCF, (3.99 +/- 1.55) Hz] were lower than those in the internal and external control group (P < 0.05), while the abnormal rates of viscidity, sperm motility and total aberration rate were higher than those in the external control group (P < 0.05). CONCLUSION: Occupational exposure to carbaryl production can affect the workers'sperm and semen quality to certain extent.

[Effects of fenvalerate exposure on the semen quality of occupational workers].

OBJECTIVES: To study the effects of fenvalerate exposure on the semen quality of occupational workers in order to find out the early effective biomarkers. METHODS: Thirty-two male workers who exposed to fenvalerate and 46 male administrators in the office in a pesticide factory were selected as the exposure group and internal control group, respectively, and 22 male administrators in a center for disease control were served as the external control group. In order to evaluate the exposed levels, the concentration of fenvalerate, toluene and xylene in the ambient air of working place in these three groups were monitored simultaneously for three consecutive days. After the semen were collected according to the standard method, the workers' semen qualities were analysed with University of California at Davis (UCDavis) method and the sperm motility were evaluated using computer assisted sperm analysis(CASA). RESULTS: In the exposure group, the concentrations of fenvalerate were significantly higher than those in the internal and external control group (P < 0.01), while no significant difference of the concentration on toluene or xylene was found (P > 0.05). Sperm motion parameters in the exposure group such as linearity(LIN), straightness(STR), and the sperm count were decreased significantly, and the abnormality rate of viscidity, coagulation and sperm count were increased significantly as compared with the internal and the external control groups(P < 0.05). Furthermore, the sperm progression and beat cross frequency (BCF) in the exposure group were also lower significantly than those in the external control group(P < 0.05), while the abnormality rate of sperm progression was increased significantly. CONCLUSIONS: In such a low concentration, occupational exposure to fenvalerate can affect workers' semen quality, especially the sperm count and sperm movement ability.