In December of 3 years, 87 beef cows with nursing calves （.594 ± 9.8 kg; calving season, September to November） at side were stratified by body condition score, body weight, cow age, and calf gender and divided...In December of 3 years, 87 beef cows with nursing calves （.594 ± 9.8 kg; calving season, September to November） at side were stratified by body condition score, body weight, cow age, and calf gender and divided randomly into 6 groups assigned to 1 of 6 cool-season annual pastures （0.45 ha/cow） that had been interseeded into a dormant common bermudagrass （Cynodon dactylon [L.] Pers.）/bahiagrass （Paspalum notatum Flugge） sod. Pastures contained 1 of the following 3 seeding mixtures （2 pastures/mixture）： 1） wheat （Triticum aestivurn L.） and ryegrass （Lofium multiflorum Lain., WRG）, 2） wheat and ryegrass plus red clover （Trifolium pretense L, WRR）, or 3） wheat and ryegrass plus white （Trifofium repens L.） and crimson clovers （Trifolium incarnatum L., WRW）. All groups had ad libitum access to grass hay （12% crude protein; 58% total digestible nutrients）. The second week in December, cow estrous cycles were synchronized and artificially inseminated. In late December, a bull was placed with each group for 60-d. Data were analyzed with an analysis of variance using a mixed model containing treatment as the fixed effect and year as the random effect. Body weight and condition scores did not differ （P ≥ 0.27） among cows between February and June. Calf birth weights or average daily gain did not differ （P≥ 0.17） among treatments; however, calves grazing pastures with clovers did tend （P= 0.06） to weigh more than calves grazing grass only. Weaning weight per cow exposed to a bull was greater （P= 0.02） for WRR and WRW than WRG. Cows grazing winter-annual pastures containing clovers tended to wean more calf body weight per cow exposed to a bull than cows grazing the grass only pastures.展开更多
Two hundred and seventy multiparous Chinese Yellow cattle (beef) were selected at 1 to 3 months postpartum and divided into three groups (90 cows for each). Animals were given both a primary and booster immunizations ...Two hundred and seventy multiparous Chinese Yellow cattle (beef) were selected at 1 to 3 months postpartum and divided into three groups (90 cows for each). Animals were given both a primary and booster immunizations with a total dose of 3 mg (Group Th) or 1.5 mg (Group Tl) of seminal preparation containing inhibin activity, emulsified with Freund's complete adjuvant and incomplete adjuvant (for booster) , at 3 or 4-week intervals. Other cows were treated with the same volume of seminal preparation without inhibin activity as procedures mentioned above to serve as a control (Group C). Artificial inseminations were given twice at 8 - 12 h intervals when the cow was in heat. Jugular venous blood samples were collected from each cow and used to assay the presence of antibody against seminal preparation by double-diffusion in agar precipitation test and to detect the titer of inhibin antibody by an ELISA method. Data from 247 cows showed that 83.9% (73/87) of cows were in estrus and ovulated 89 ova altogether, of which 19 cows ovulated twin ova and 15 cows produced twins in Group Th (n = 87). However, only 61.1% (44/72) of cows in Group TI (n = 72) and 62.5% (55/88) of cows in Group C were in estrus and ovulated 46 and 52 ova altogether respectively. The ovulation rate (1.27 ± 0.03), calving rate (126.3%) and twinning rate (26.3%) in Group Th were greater than those in Groups Tl or C (P<0.01). Furthermore, the ovulation rate was associated with antibody titer in sera of immunized animals (r = 0.7507, P<0.01). These results indicate that active immunization of postpartum cows against inhibin purified from porcine seminal plasma may increase the ovulation rate and induce twinning, suggesting the potential to develop a method to improve fertility in cows.展开更多
Global livestock production is a major driver of climate change.Lumping beef and pork together as red meat masks important differences in their carbon footprints,land uses,and social status.These two red meat choices ...Global livestock production is a major driver of climate change.Lumping beef and pork together as red meat masks important differences in their carbon footprints,land uses,and social status.These two red meat choices in Canada were compared by using a meta-model of the Unified Livestock Industry and Crop Emissions Estimation System(ULICEES).ULICEES calculated fossil CO_(2),N_(2)O and CH_(4) emissions for beef,dairy,pork,poultry,and sheep production in Canada,based on both the livestock and their supporting land base in 2001.The dynamic drivers of the meta-model were crop yields,breeding female populations,tillage practices,nitrogen fertilizer use,and the crop complex of each livestock industry.When the potential carbon sequestration in the land growing harvested perennial forage is credited to beef production,the CO_(2)e emissions offset does not reduce the carbon footprint of beef enough to match the lower carbon footprint of pork.Most of the land required to grow hay for beef would not be needed to feed a protein-equivalent pig population.In a hypothetical conversion of all beef production to pork production for 2021,4.5 Mha of land under perennial forage was freed and 10.0 MtCO_(2)e per year was mitigated when that area was re-cultivated for annual crops—a GHG mitigation equal to 12%of the GHG emissions budget of Canadian agriculture.Leaving that area under a perennial ground cover mitigated 19.8 MtCO_(2)e per year,the equivalent of 23%of the sector’s GHG emissions budget.展开更多
文摘In December of 3 years, 87 beef cows with nursing calves （.594 ± 9.8 kg; calving season, September to November） at side were stratified by body condition score, body weight, cow age, and calf gender and divided randomly into 6 groups assigned to 1 of 6 cool-season annual pastures （0.45 ha/cow） that had been interseeded into a dormant common bermudagrass （Cynodon dactylon [L.] Pers.）/bahiagrass （Paspalum notatum Flugge） sod. Pastures contained 1 of the following 3 seeding mixtures （2 pastures/mixture）： 1） wheat （Triticum aestivurn L.） and ryegrass （Lofium multiflorum Lain., WRG）, 2） wheat and ryegrass plus red clover （Trifolium pretense L, WRR）, or 3） wheat and ryegrass plus white （Trifofium repens L.） and crimson clovers （Trifolium incarnatum L., WRW）. All groups had ad libitum access to grass hay （12% crude protein; 58% total digestible nutrients）. The second week in December, cow estrous cycles were synchronized and artificially inseminated. In late December, a bull was placed with each group for 60-d. Data were analyzed with an analysis of variance using a mixed model containing treatment as the fixed effect and year as the random effect. Body weight and condition scores did not differ （P ≥ 0.27） among cows between February and June. Calf birth weights or average daily gain did not differ （P≥ 0.17） among treatments; however, calves grazing pastures with clovers did tend （P= 0.06） to weigh more than calves grazing grass only. Weaning weight per cow exposed to a bull was greater （P= 0.02） for WRR and WRW than WRG. Cows grazing winter-annual pastures containing clovers tended to wean more calf body weight per cow exposed to a bull than cows grazing the grass only pastures.
基金supported by the National Natural Science Foundation of China(No.39370512)the Foundation of Doctor Degree Unit Authorized by China Education Ministry(No.960204)the National Key Research Progress(No.96030311)of Chinese Ministry of Science and Technology,respectively.
文摘Two hundred and seventy multiparous Chinese Yellow cattle (beef) were selected at 1 to 3 months postpartum and divided into three groups (90 cows for each). Animals were given both a primary and booster immunizations with a total dose of 3 mg (Group Th) or 1.5 mg (Group Tl) of seminal preparation containing inhibin activity, emulsified with Freund's complete adjuvant and incomplete adjuvant (for booster) , at 3 or 4-week intervals. Other cows were treated with the same volume of seminal preparation without inhibin activity as procedures mentioned above to serve as a control (Group C). Artificial inseminations were given twice at 8 - 12 h intervals when the cow was in heat. Jugular venous blood samples were collected from each cow and used to assay the presence of antibody against seminal preparation by double-diffusion in agar precipitation test and to detect the titer of inhibin antibody by an ELISA method. Data from 247 cows showed that 83.9% (73/87) of cows were in estrus and ovulated 89 ova altogether, of which 19 cows ovulated twin ova and 15 cows produced twins in Group Th (n = 87). However, only 61.1% (44/72) of cows in Group TI (n = 72) and 62.5% (55/88) of cows in Group C were in estrus and ovulated 46 and 52 ova altogether respectively. The ovulation rate (1.27 ± 0.03), calving rate (126.3%) and twinning rate (26.3%) in Group Th were greater than those in Groups Tl or C (P<0.01). Furthermore, the ovulation rate was associated with antibody titer in sera of immunized animals (r = 0.7507, P<0.01). These results indicate that active immunization of postpartum cows against inhibin purified from porcine seminal plasma may increase the ovulation rate and induce twinning, suggesting the potential to develop a method to improve fertility in cows.
文摘Global livestock production is a major driver of climate change.Lumping beef and pork together as red meat masks important differences in their carbon footprints,land uses,and social status.These two red meat choices in Canada were compared by using a meta-model of the Unified Livestock Industry and Crop Emissions Estimation System(ULICEES).ULICEES calculated fossil CO_(2),N_(2)O and CH_(4) emissions for beef,dairy,pork,poultry,and sheep production in Canada,based on both the livestock and their supporting land base in 2001.The dynamic drivers of the meta-model were crop yields,breeding female populations,tillage practices,nitrogen fertilizer use,and the crop complex of each livestock industry.When the potential carbon sequestration in the land growing harvested perennial forage is credited to beef production,the CO_(2)e emissions offset does not reduce the carbon footprint of beef enough to match the lower carbon footprint of pork.Most of the land required to grow hay for beef would not be needed to feed a protein-equivalent pig population.In a hypothetical conversion of all beef production to pork production for 2021,4.5 Mha of land under perennial forage was freed and 10.0 MtCO_(2)e per year was mitigated when that area was re-cultivated for annual crops—a GHG mitigation equal to 12%of the GHG emissions budget of Canadian agriculture.Leaving that area under a perennial ground cover mitigated 19.8 MtCO_(2)e per year,the equivalent of 23%of the sector’s GHG emissions budget.
