[Effects of 24 Years Different Straw Return on Soil Carbon, Nitrogen, Phosphorus, and Extracellular Enzymatic Stoichiometry in Dryland of the Loess Plateau, China].

Exploring the biogeochemical cycle characteristics of soil carbon, nitrogen, and phosphorus in farmland in the dryland of the loess plateau can provide scientific basis and technical support for efficient crop production and sustainable land use. Here, based on a long-term (24 year) straw return field experiment in Shouyang, Shanxi province, the effects of different straw return regimes, i.e., straw mulching (SM), direct straw return (DS), animal-digested straw return (AS), and non-straw return (CK), on the stoichiometric ratio of soil elements and extracellular enzyme activities were studied. The vector angle and length were calculated to indicate the resource constraints faced by microorganisms. The vector angle was greater than 45° and less than 45°, indicating that microorganisms were limited by phosphorus and nitrogen, respectively. The greater the deviation from 45°, the greater the degree of limitation, and the longer the vector length, the more severely limited by carbon. The results showed that ① the soil C/N and C/P of long-term straw returning ranged from 9.81 to 14.28 and from 14.58 to 21.92, with the mean values of 12.36 and 17.51, respectively, which were 6.0% and 4.2% lower than that at the initial stage of the experiment. The soil N/P was distributed between 1.27 and 1.57, with an average of 1.42, which was 2.2% higher than that in the initial stage. The soil C/N and C/P ratios showed a trend of first decreasing and then increasing, the soil N/P ratio basically showed a flat trend, and there was no significant difference in soil element metering ratios between different straw returning treatments. ② Compared with the 24-year long-term non-straw return treatment, the activities of ß-1,4-glucosidase (BG) and ß-1,4-N-acetylglucosaminidase (NAG) in the soil of the long-term straw mulching treatment increased by 134.4% and 107.5% (P<0.05), the activities of BG and alkaline phosphatase (AP) in the soil of the long-term straw mulching treatment decreased by 59.3% and 59.5% (P<0.05), respectively, and the activities of NAG in the soil of the long-term straw mulching treatment increased by 102.8% (P<0.05). Under the long-term straw returning treatment, soil microorganisms were faced with carbon and phosphorus limitation as a whole. Long-term straw mulching aggravated microbial carbon limitation, and animal-digested straw return could alleviate the degree of carbon limitation. Compared with that in the 24-year long-term non-straw return treatment, soil EEAC/N could be significantly reduced by the animal-digested straw return treatment, and soil EEAC/P could be increased by the direct straw return treatment. The three straw returning methods had no significant indigenous effect on soil EEAN/P. The overall vector angle was greater than 45°, and the vector length increased by 3.8%-20.1% compared with that in the initial stage. ③ Correlation analysis showed that C and N inputs were significantly negatively correlated with BG activity; available nitrogen was significantly correlated with NAG activity, AP activity, and EEAC/N; C/P was significantly positively correlated with EEAC/N; there were significant correlations between N/P and NAG activity, AP activity, EEAC/N, and EEAC/P; and there was no significant correlation between EEAN/P and any environmental factors. In conclusion, the availability of soil nitrogen and phosphorus elements and N/P ratio had significant effects on soil extracellular enzyme activity and stoichiometric characteristics under different long-term straw returning treatments. In the future, more attention should be paid to the improvement of organic carbon and the promotion of nitrogen and phosphorus availability in farmland soil in soil-efficient cultivation and agricultural production activities.

Dietary supplementation with pioglitazone hydrochloride improves intramuscular fat, fatty acid profile, and antioxidant ability of thigh muscle in yellow-feathered chickens.

BACKGROUND: Muscle fat content and fatty acid composition play an important role in poultry flavor and taste. To investigate the effects of pioglitazone hydrochloride (PGZ) on growth performance and thigh muscle quality in yellow-feathered chickens, 360 female chickens were randomly divided into three groups and treated with three doses of PGZ (0, 7.5, and 15 mg kg-1 ) for 28 days. Each group had six replicates of 20 chickens. RESULTS: The results showed that dietary supplementation with 15 mg kg-1 PGZ increased average daily feed intake (ADFI) and the average daily gain (ADG) from 0 to 14 days. Furthermore, the triglyceride (TG) level was decreased by 15 mg kg-1 PGZ, whereas the eviscerated yield was increased. The relative weight of the heart and kidneys showed a linear increase with dietary PGZ supplementation, and the drip loss of the thigh muscle was significantly decreased by 15 mg kg-1 PGZ supplementation. Moreover, a* value, intramuscular fat (IMF), and polyunsaturated fatty acids (PUFAs) showed a linear increase, and pH24 h and drip loss showed a quadratic influence with the levels of PGZ supplementation. In particular, the PUFA proportion was increased by 7.63% and 9.14% in the 7.5 mg kg-1 PGZ and 15 mg kg-1 PGZ groups, respectively. Additionally, 15 mg kg-1 of PGZ increased the total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-PX ) activity. CONCLUSION: In summary, 15 mg kg-1 PGZ has substantial effects on growth performance and meat quality, particularly by decreasing drip loss and increasing IMF content, PUFA proportions, and antioxidant ability. © 2019 Society of Chemical Industry.

[Reducing oxidative DNA damage by adding antioxidants in human semen samples undergoing cryopreservation procedure].

OBJECTIVE: To evaluate the protective effects of oxidative DNA damage by adding antioxidants: ascorbate, catalase (CAT), and superoxide dismutase (SOD) in human semen samples undergoing cryopreservation procedure. METHODS: Semen sample form 30 fertile men were mixed with modified cryoprotectant and divided into six groups according to the category and concentration of antioxidants: ascorbate 300 micromol/L, ascorbate 600 micromol/L, CAT 200 U/ml, CAT 400 U/ml, SOD 200 U/ml, and SOD 400 U/ml. Comet assay was conducted to measure the percentage of comet cells, and the nuclear DNA damaged parameters: tail DNA percentage (TD%) and Olive tail moment (OTM). Flow cytometry was used to detect the reactive oxidative species (ROS). The motility (a + b grade), viable recovery rate, nuclear DNA integrity and reactive oxidative species (ROS) of all groups were analyzed before and/or after freeze-thawing. RESULTS: (After cryopreservation, compared with the control group, the a + b grade sperm rates of the ascorbate 300 micromol/L, CAT 200 U, and CAT 400 U groups were all higher than that of the control group (all P < 0.05), however, the levels of reactive oxygen species (ROS) of the ascorbate 300 micromol/L, CAT 200 U, and CAT 400 U groups were 30 +/- 13, 30 +/- 11, and 30 +/- 11 respectively, all significantly lower than that of the control group (37 +/- 17 , all P < 0.05). The viable recovery rates of the ascorbate 300 micromol/L , CAT 200 U, and CAT 400 U groups were 67% +/- 14%, 68% +/- 14%, and 69% -/+ 15% respectively, all significantly higher than that of the control group (59% +/- 10%, all P < 0.05). (2) The TD% levels of the ascorbate 300 micromol/L, CAT 200 U, and CAT 400 U groups were 41% +/- 4%, 40% +/- 7%, 40% +/- 6%, all similar to that of the raw semen (all P > 0.05), but significantly lower than that of the control group (46% +/- 6%, all P < 0.01). The OTM levels of the ascorbate 300 micromol/ L, CAT 200 U, and CAT 400 U groups were 7.7 +/- 1.2, 7.5 +/- 1.6, and 7.8 +/- 1.9, all similar to that of the raw semen (all P > 0.05), but significantly lower than that of the control group (10.1 +/- 3.1, all P < 0.01) too. The TD% and OTM levels of the other groups were all significantly higher than that of the raw semen (all P < 0.01), but not significantly different from those of the control group (all P > 0.05). (3) ROS was significantly negatively correlated with the motility in all groups (P < 0.05 or P < 0.01). Apart from the ascorbate 600 micromol/L group, the TD% and OTM of the other groups were all significantly positively correlated with the ROS (P < 0.05 or P < 0.01). CONCLUSION: Supplementation of ascorbate or CAT reduces the level of ROS that induces sperm nuclear DNA damage, and improves the human sperm quality in the process of freeze-thawing.