Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at...Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at regular intervals.As these processes are affected by the cows’nutritional or metabolic status post-calving,the objective of this study was to evaluate the effect of cow feeding strategies on uterine health,the length of postpartum anestrous interval,and reproductive outcomes.The treatments consisted of two feeding strategies during late-lactation and early dry period(far-off period;starting 4-month pre-calving)and three close-up dry period feeding regimes(1-month pre-calving)in a 2×3 factorial arrangement.We randomly assigned 150 cows to one of two far-off treatments.During late lactation,the herds(n=75 cows per herd)were either control-fed(Controlfed)or over-fed(Overfed)to achieve a low or high body condition score(4-month pre-calving;BCS;~4.25 and^4.75;10-point scale)at cessation of lactation.Within each of these treatments,three feeding levels were applied during the close-up period(1-month pre-calving):~65%(Feed65),~90%(Feed90),or^120%(Feed120)of metabolizable energy(ME)intakes relative to pre-calving requirements.Results:Uterine health improved(i.e.polymorphonucleated(PMN)cells declined)with increased feeding during the close-up period for cows in the Overfed group.The reverse was evident for the Controlfed group with the greatest PMN at the highest intakes during the close-up period.The postpartum anoestrous interval(PPAI)was shorter in cows from the Overfed group when moderately fed(Feed90)during the close-up period;in comparison,the PPAI was shorter in the Controlfed group,when those cows were overfed in the close-up period(Feed120).The cows in the Overfed treatment had greater conception and pregnancy rates if cows had moderate dry matter intakes(Feed90)during the close-up period;these reproductive variables were less under excessive feed intakes(Feed120);yet,close-up dry matter intake had little effect on conception and pregnancy rates for the Controlfed group.Conclusions:The far-off feeding strategies increased early reproductive outcomes at 3 weeks of mating.Additionally,the interaction between far-off and close-up feeding strategies resulted in high six-week pregnancy rate with a slight restriction during the close-up period but only in the far-off Overfed group.Thus,our hypothesis is supported under these conditions.展开更多
Based on our work on single cesium atoms trapped in a large-magnetic-gradient vapour-cell magneto-optical trap （MOT）, the signal-to-noise ratio （SNR） is remarkably improved. Also a far-off-resonance optical dipole...Based on our work on single cesium atoms trapped in a large-magnetic-gradient vapour-cell magneto-optical trap （MOT）, the signal-to-noise ratio （SNR） is remarkably improved. Also a far-off-resonance optical dipole trap （FORT） formed by a strongly-focused 1064 nm single frequency Nd：YVO4 laser beam is introduced. One cesium atom is prepared in the MOT, and then it can transfer successfully between the MOT and the FORT which is overlapped with the MOT. Utilizing the effective transfer, the lifetime of single atoms trapped in the FORT is measured to be 6.9± 0.3 s. Thus we provide a system where the atomic qubit can be coherently manipulated.展开更多
In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The ...In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The efficient transfer of the single atom between the two traps is used to determine the trapping lifetime and the effective temperature of the single atom in FORT. The typical trapping lifetime has been improved from ~ 6.9 s to ~ 130 s by decreasing the background pressure from 1 × 10^-10 Torr to ~ 2 × 10^-11 Torr and applying one-shot 10-ms laser cooling phase. We also theoretically investigate the dependence of trapping lifetimes of a single atom in a FORT on trap parameters based on the FORT beam＇s intensity noise induced heating. Numerical simulations show that the heating depends on the FORT beam＇s waist size and the trap depth. The trapping time can be predicted based on effective temperature measurement of a single atom in the FORT and the intensity noise spectra of the FORT beam. These experimental results are found to be in agreement with the predictions of the heating model.展开更多
基金supported by New Zealand dairy farmers through DairyNZ Inc.(RD1403)the Ministry of Business,Innovation,and Employment(DRCX1201).
文摘Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at regular intervals.As these processes are affected by the cows’nutritional or metabolic status post-calving,the objective of this study was to evaluate the effect of cow feeding strategies on uterine health,the length of postpartum anestrous interval,and reproductive outcomes.The treatments consisted of two feeding strategies during late-lactation and early dry period(far-off period;starting 4-month pre-calving)and three close-up dry period feeding regimes(1-month pre-calving)in a 2×3 factorial arrangement.We randomly assigned 150 cows to one of two far-off treatments.During late lactation,the herds(n=75 cows per herd)were either control-fed(Controlfed)or over-fed(Overfed)to achieve a low or high body condition score(4-month pre-calving;BCS;~4.25 and^4.75;10-point scale)at cessation of lactation.Within each of these treatments,three feeding levels were applied during the close-up period(1-month pre-calving):~65%(Feed65),~90%(Feed90),or^120%(Feed120)of metabolizable energy(ME)intakes relative to pre-calving requirements.Results:Uterine health improved(i.e.polymorphonucleated(PMN)cells declined)with increased feeding during the close-up period for cows in the Overfed group.The reverse was evident for the Controlfed group with the greatest PMN at the highest intakes during the close-up period.The postpartum anoestrous interval(PPAI)was shorter in cows from the Overfed group when moderately fed(Feed90)during the close-up period;in comparison,the PPAI was shorter in the Controlfed group,when those cows were overfed in the close-up period(Feed120).The cows in the Overfed treatment had greater conception and pregnancy rates if cows had moderate dry matter intakes(Feed90)during the close-up period;these reproductive variables were less under excessive feed intakes(Feed120);yet,close-up dry matter intake had little effect on conception and pregnancy rates for the Controlfed group.Conclusions:The far-off feeding strategies increased early reproductive outcomes at 3 weeks of mating.Additionally,the interaction between far-off and close-up feeding strategies resulted in high six-week pregnancy rate with a slight restriction during the close-up period but only in the far-off Overfed group.Thus,our hypothesis is supported under these conditions.
基金supported by the National Natural Science Foundation of China (Grant Nos 60578018 and 10434080)the project for excellent research team from the National Natural Science Foundation of China (Grant No 60821004)+4 种基金the Program for New Century Excellent Talents of the Education Ministry of China (Grant No NCET-07-0524)the State Basic Key Research Program of China (Grant No 2006CB921102)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No 20070108003)the Natural Science Foundation of Shanxi Province,China (Grant No 2007011003)the Scientific Research Funds for Returned Scholars Abroad of Shanxi Province,China
文摘Based on our work on single cesium atoms trapped in a large-magnetic-gradient vapour-cell magneto-optical trap （MOT）, the signal-to-noise ratio （SNR） is remarkably improved. Also a far-off-resonance optical dipole trap （FORT） formed by a strongly-focused 1064 nm single frequency Nd：YVO4 laser beam is introduced. One cesium atom is prepared in the MOT, and then it can transfer successfully between the MOT and the FORT which is overlapped with the MOT. Utilizing the effective transfer, the lifetime of single atoms trapped in the FORT is measured to be 6.9± 0.3 s. Thus we provide a system where the atomic qubit can be coherently manipulated.
基金Acknowledgements This work was supported by the Na- tional Natural Science Foundation of China （Grant Nos. 60978017, 61078051, and 10974125）, the project from excellent research team from the National Natural Science Foundation of China （Grant No. 60821004）, and the NCET Program from the Ministry of Educa- tion of China （Grant No. NCET-07-0524）.
文摘In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The efficient transfer of the single atom between the two traps is used to determine the trapping lifetime and the effective temperature of the single atom in FORT. The typical trapping lifetime has been improved from ~ 6.9 s to ~ 130 s by decreasing the background pressure from 1 × 10^-10 Torr to ~ 2 × 10^-11 Torr and applying one-shot 10-ms laser cooling phase. We also theoretically investigate the dependence of trapping lifetimes of a single atom in a FORT on trap parameters based on the FORT beam＇s intensity noise induced heating. Numerical simulations show that the heating depends on the FORT beam＇s waist size and the trap depth. The trapping time can be predicted based on effective temperature measurement of a single atom in the FORT and the intensity noise spectra of the FORT beam. These experimental results are found to be in agreement with the predictions of the heating model.
