[Objective]This experiment was conducted to investigate the effects of heat stress on microbial numbers in rumen fluid of dairy cows during different lactating periods by real-time PCR.[Methods]A 2 ×3 crossover d...[Objective]This experiment was conducted to investigate the effects of heat stress on microbial numbers in rumen fluid of dairy cows during different lactating periods by real-time PCR.[Methods]A 2 ×3 crossover design was used and eighteen healthy Chinese Holstein cows were selected.The cows were allocated into three periods based on their parity,average days in milk,and milk yield：early lactation（postpartum 15 to 100 days）,mid-lactation（postpartum 112 to 175 days）and late lactation（postpartum 200 to 230 days）,and six cows in each period.A self-control trial between heat stress period and non-heat stress period was used based on temperature and humidity index（THI）measurement on site.[Results]The results showed as follows：compared with non-heat stress period,heat stress significantly increased the microbial numbers in early lactation,the Ruminococcus flavefaciens number in different lactation and Bacteroides succinogenes number in early and mid-lactation（P 〈0.01）.The total bacteria and Ruminococcus albus numbers in mid-and late lactation and Bacteroides succinogenes number in late lactation were decreased significantly by heat stress（P 〈0.01）.There were strong correlation between THI and the numbers of total bacteria（P 〈0.01）,anaerobic fungi（P 〈0.05）,Ruminococcus albus（P 〈0.01）and Ruminococcus flavefaciens（P 〈0.05）in rumen fluid of dairy cows in early lactation,but the correlation between THI and these indexes in mid-and late lactation were poor.[Conclusion]It is indicated that the rumen microbial numbers in early lactation are more sensitive to heat stress.展开更多
An experimental study of the rhizosphere effect on phytoremediation of petroleum polluted soil was carried out with three species of grasses, namely Pannicum, Eleusine indica （L.） Gaerth, and Tall Fescue. After a pe...An experimental study of the rhizosphere effect on phytoremediation of petroleum polluted soil was carried out with three species of grasses, namely Pannicum, Eleusine indica （L.） Gaerth, and Tall Fescue. After a period of 150 days, this pot experiment showed that the rhizosphere of these three species accelerated the degradation of petroleum hydrocarbons to different extents. The results showed that the number of microorganisms in the rhizosphere increased by three orders of magnitude. The induction of the plant rhizosphere and the coercion influence of petroleum changed the species and activity of microorganisms. The degradation of petroleum hydrocarbons in the rhizosphere was 3-4 times that in unplanted soil. The dehydrogenase activity in the rhizosphere was 1.61-2.20 times that in unplanted soil, but the catalase activity was 0.90-0.93 times that in unplanted soil, and soil moisture content increased by 5% compared with the unplanted soil.展开更多
基金funded by Nonprofit sector (agriculture) research projects (200903003)
文摘[Objective]This experiment was conducted to investigate the effects of heat stress on microbial numbers in rumen fluid of dairy cows during different lactating periods by real-time PCR.[Methods]A 2 ×3 crossover design was used and eighteen healthy Chinese Holstein cows were selected.The cows were allocated into three periods based on their parity,average days in milk,and milk yield：early lactation（postpartum 15 to 100 days）,mid-lactation（postpartum 112 to 175 days）and late lactation（postpartum 200 to 230 days）,and six cows in each period.A self-control trial between heat stress period and non-heat stress period was used based on temperature and humidity index（THI）measurement on site.[Results]The results showed as follows：compared with non-heat stress period,heat stress significantly increased the microbial numbers in early lactation,the Ruminococcus flavefaciens number in different lactation and Bacteroides succinogenes number in early and mid-lactation（P 〈0.01）.The total bacteria and Ruminococcus albus numbers in mid-and late lactation and Bacteroides succinogenes number in late lactation were decreased significantly by heat stress（P 〈0.01）.There were strong correlation between THI and the numbers of total bacteria（P 〈0.01）,anaerobic fungi（P 〈0.05）,Ruminococcus albus（P 〈0.01）and Ruminococcus flavefaciens（P 〈0.05）in rumen fluid of dairy cows in early lactation,but the correlation between THI and these indexes in mid-and late lactation were poor.[Conclusion]It is indicated that the rumen microbial numbers in early lactation are more sensitive to heat stress.
基金This work was supported by the National Natural Science Foundation of China under grant No.40672211.
文摘An experimental study of the rhizosphere effect on phytoremediation of petroleum polluted soil was carried out with three species of grasses, namely Pannicum, Eleusine indica （L.） Gaerth, and Tall Fescue. After a period of 150 days, this pot experiment showed that the rhizosphere of these three species accelerated the degradation of petroleum hydrocarbons to different extents. The results showed that the number of microorganisms in the rhizosphere increased by three orders of magnitude. The induction of the plant rhizosphere and the coercion influence of petroleum changed the species and activity of microorganisms. The degradation of petroleum hydrocarbons in the rhizosphere was 3-4 times that in unplanted soil. The dehydrogenase activity in the rhizosphere was 1.61-2.20 times that in unplanted soil, but the catalase activity was 0.90-0.93 times that in unplanted soil, and soil moisture content increased by 5% compared with the unplanted soil.
