Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of ...Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of records of 2496 Chinese Holsteins first lactation cows collected from 1989 to 2000.The model included 21 herd effects,four calving season effects,nine age at first calving effects,6697 animal effects.(Co)variance components of milk yield,fat yield and age at first calving were estimated with the software package for variance component estimation(VCE) by an animal model. The heritabilities were 0.14,0.21,0.38 for milk yield,fat yield and age at first calving,respectively.The estimates of genetic correlation between milk yield and fat yield,age at first calving were 0.96,-0.29,respectively.The estimate of genetic correlation between fat yield and age at first calving was -0.28.展开更多
A massive iceberg, named A-68 by National Ice Center （NIC） officially, calved away from the Larsen C Ice Shelf in Antarctica on luly 12, 2017. The iceberg A-68 is about 5 800 km2, weighs more than a trillion tons an...A massive iceberg, named A-68 by National Ice Center （NIC） officially, calved away from the Larsen C Ice Shelf in Antarctica on luly 12, 2017. The iceberg A-68 is about 5 800 km2, weighs more than a trillion tons and it is one of the biggest ever recorded icebergs. Chinese satellites Gaofen-1 （GF-1） and Gaofen-3 （GF-3） data was used to monitoring the propagation of the rift and the iceberg by National Satellite Ocean Application Service （NSOAS）.展开更多
Age at first calving (AFC) affects the profitability of dairy enterprises. This study examined the relationships between AFC and subsequent fertility, milk production and survival up to third calving in UK Holstein-Fr...Age at first calving (AFC) affects the profitability of dairy enterprises. This study examined the relationships between AFC and subsequent fertility, milk production and survival up to third calving in UK Holstein-Friesian heifers;Study 1 comprised 134 consecutively born heifers from the same herd (AFC 764 ± 8 days) and Study 2 contained 445 heifers born on 17 farms (AFC 796 ± 6 days). Growth rates and fertility during rearing were monitored and animals were subsequently divided into four AFC groups for analysis: <23 months, 23 - 25 months, 26 - 30 months and >30 months. The actual AFC reflected both growth rate and heifer fertility, with later calving heifers already lighter by 6 months of age. The proportion conceiving to first service was highest (93% and 84% for Studies 1 and 2, respectively) for the youngest AFC group. Fertility in the first lactation was best in cows calving at 23 - 25 months and worst in the oldest AFC group. Milk production parameters in the first and second lactations were broadly similar between AFC groups but significantly more heifers with an AFC < 26 months calved for a third time. These younger calving animals therefore achieved more days in milk over 5 years, with >44% of their days alive spent in milk production compared with only 18% - 40% in cows calving at ≥26 months. Hence cows with an AFC < 26 months produced the most milk in their first 5 years of life. These results indicate that an AFC of 0.75 kg/d up to 15 months and good heifer fertility and resulted in the best subsequent performance.展开更多
Mass loss caused by glacier calving is one of the direct contributors to global sea level rise.Reliable calving laws are required for accurate modelling of ice sheet mass balance.Both continuous and discontinuous meth...Mass loss caused by glacier calving is one of the direct contributors to global sea level rise.Reliable calving laws are required for accurate modelling of ice sheet mass balance.Both continuous and discontinuous methods have been used for glacial calving simulations.In this study,the discrete element method(DEM)based on dilated polyhedral elements is introduced to simulate the calving process of a tidewater glacier.Dilated polyhedrons can be obtained from the Minkowski sum of a sphere and a core polyhedron.These elements can be utilized to generate a continuum ice material,where the interaction force between adjacent elements is modeled by constructing bonds at the joints of the common faces.A hybrid fracture model considering fracture energy is introduced.The viscous creep behavior of glaciers on long-term scales is not considered.By applying buoyancy and gravity to the modelled glacier,DEM results show that the calving process is caused by cracks which are initialized at the top of the glacier and spread to the bottom.The results demonstrate the feasibility of using the dilated polyhedral DEM method in glacier simulations,additionally allowing the fragment size of the breaking fragments to be counted.The relationship between crack propagation and internal stress in the glacier is analyzed during calving process.Through the analysis of the Mises stress and the normal stress between the elements,it is found that geometric changes caused by the glacier calving lead to the redistribution of the stress.The tensile stress between the elements is the main influencing factor of glacier ice failure.In addition,the element shape,glacier base friction and buoyancy are studied,the results show that the glacier model based on the dilated polyhedral DEM is sensitive to the above conditions.展开更多
This study was conducted to estimate variance components and genetic parameters for 305 days mature equivalent milk yields (MEM) and calving interval (CAI) of registered Xinjiang Brown cattle. The total records were 3...This study was conducted to estimate variance components and genetic parameters for 305 days mature equivalent milk yields (MEM) and calving interval (CAI) of registered Xinjiang Brown cattle. The total records were 3940 including 2579 for 305-day MEM and 1970 for CAI, which were collected from Xinjiang Urumqi Cattle Breeding farm in China with calving records from 1990 to 2008. Genetic parameters were obtained by multiple trait derivative-free restricted maximum likelihood (MTDFREML) using animal model. The model included year, season, parity and calving interval of calving for 305 days MEM, and year, season and parity of birth for CAI as fixed effects. Heritability for 305 days MEM was moderate (0.39) and in the same range of parameters estimated in management systems with medium production levels. Heritability of calving interval was small (0.02) as fertility traits for Xinjiang Brown cattle. Estimates of genetic and environmental correlations between 305 days MEM and CAI were 0.47 and 0.37, respectively. Estimates of genetic variation and heritability indicated that selection would result in genetic improvement of production traits. Estimates of both heritability and genetic variation for CAI were small, which indicates that genetic improvement would be difficult.展开更多
A total of 5852 records concerning daily milk yield, content of protein and fat, and somatic cell count was recorded in two farms (organic and conventional). Somatic cell count was log10- transformed before analysis b...A total of 5852 records concerning daily milk yield, content of protein and fat, and somatic cell count was recorded in two farms (organic and conventional). Somatic cell count was log10- transformed before analysis because was not normally distributed. The mixed model methodology was used according to a repeated-measures scheme, as the restricted maximum likelihood method to estimate lactation curves at different season of calving and at different calving order. Calving order affected milk yield only in the first three calving order with the lowest production levels in the first six months of the year for both farm;no effect could be observed on fat and protein contents. The organic farm shows the minor milk production (7.77 vs8.10 kg/day/head organic and traditional respectively), but good qualitative characteristics of milk, and minor content of Somatic Cell Count. The milk production is major, in traditional farm, in summer respect the winter (10.4 vs6.34 kgof milk/day/ head). In biological farm no difference between seasons were observed. Peak milk yield occurs, for both farms, at around the 6th - 7th wk of lactation.展开更多
The SNIT theory proposes the effects of exploding stars,supernova and nova,on the biosphere of Earth.The feature on our planet that is most sensitive to the incoming energy of an exploding star is sea ice at the poles...The SNIT theory proposes the effects of exploding stars,supernova and nova,on the biosphere of Earth.The feature on our planet that is most sensitive to the incoming energy of an exploding star is sea ice at the poles and this brings in the concept of global warming.The incoming particle streams for SN 1054,SN 1006,and Nova WZ Sagittae have left easily interpreted data noted as calving under the Antarctic ice cap that matches previously predicted longitude locations for the local heat input of the particle streams of the exploding stars.Animal die offs are also caused by the incoming particle streams.The deflection area longitude range for SN 1054 calving produces the correct longitude range for the moose die off beginning in the northern USA in 2006.Some Martian dust storms are created by the wave front of the exploding star debris streams.The explanation of these exploding stars effects using the SNIT theory is the object of this work.展开更多
Good management of the pregnant heifer is crucial to ensure that she is well grown and healthy and calves down easily before joining the milking herd. This study collected primary data on all aspects of heifer managem...Good management of the pregnant heifer is crucial to ensure that she is well grown and healthy and calves down easily before joining the milking herd. This study collected primary data on all aspects of heifer management on 101 UK farms during heifer pregnancy from conception to calving including farm factors and associated costs of system inputs. A cost analysis workbook was developed to calculate the cost of rearing per heifer for each of the study farms. Associations between cost of rearing and farms factors were determined using linear regression and analysis of variance. Heifers had a mean age of conception of 509 d (range 365 - 700 d) and an age at first calving of 784 d (range 639 - 973 d). The mean total cost of rearing during pregnancy was ￡450.36 (range ￡153.11 to ￡784.00) with a mean daily cost of ￡1.64 (range ￡0.56 to ￡2.86). The inputs contributing the most to cost were feed (32.7%), labour (23.8%) and slurry disposal (11.2%). Total purchased and homegrown feed and grazing contributed between 25.5% and 65.4% of total costs with a mean contribution of 43.6%. The cost of rearing was lowest in spring calving herds and highest in all year round calving herds with intermediate values in autumn and multi block calving herds. The main variables influencing the cost were the number of days spent at grass, age at first calving, calving pattern, breed, herd size and region. Each extra day in age at first calving increased the mean cost of rearing during pregnancy by ￡0.33/d whereas every extra day at grass reduced the cost by ￡1.75/d.展开更多
The objective of this study was to evaluate the relationship of the calving number with productive indicators in Nelore cows in a grazing system in the Bolivian tropics.Retrospective data,corresponding to the period b...The objective of this study was to evaluate the relationship of the calving number with productive indicators in Nelore cows in a grazing system in the Bolivian tropics.Retrospective data,corresponding to the period between 1991 and 2019 referred to 1,566 primiparous and multiparous Nelore breed cows were used.A decrease in the total number of animals was observed from the first to the fifth calving,it was also observed that the age of the first calving was similar in all cows without significant differences,showing that longevity is not associated with the age at the first calving.Live weight presented significant differences(p≤0.05),according to the number of calvings;the fourth and fifth calving cows are the heaviest.Weight of calf at birth did not show a relationship with the number of calvings either.However,it does so in the weight of calf at weaning,which increases from the first to the fifth calving with significant differences(p≤0.05).There were significant differences(p≤0.05)for the interval between calvings,decreasing as the calvings progressed.It is concluded that there is a relationship between the number of calving with productive indicators in Nelore cows in a grazing system in the Bolivian tropics,fundamentally those efficiency variables where longevity is important.展开更多
Most probable producing ability （MPPA） is the one factor used to compare the performance potential of dam based on the data of their progeny. The purpose of the research was to study the genetic ability of weaning w...Most probable producing ability （MPPA） is the one factor used to compare the performance potential of dam based on the data of their progeny. The purpose of the research was to study the genetic ability of weaning weight, yearling weight and calving interval of Bali cows. The weaning weight data of 296 cows derived from 99 dams, yearling weight data of 245 cows derived from 86 dams and cabAng interval data of 194 cows from 63 dams were used to estimate repeatability and MPPA of Bali cows in a herd for the three traits. Repeatability of three traits was estimated by analysis of intra-class correlation, and these in turn were used for calculating the estimated MPPA of cows. The results showed that the means of weaning weight of males and females were 95.56 ± 17.25 kg and 87.57 ± 18.45 kg, respectively; means of yearling weight were 143.39 ±25.78 kg and 136.90 ± 22.01 kg, respectively; and mean calving interval was 391.62±22.59 d. The estimated repeatability of weaning weight, yearling weight and calving interval were 0.006 ±0.059, 0.022 ± 0.068 and 0.115 ± 0.078, respectively. The best 10 dams in the herd based on the estimates of MPPA for weaning weight, yearling weight and calving interval were not the same for the three traits.展开更多
The stability of the Larsen C Ice Shelf(LIS)has been widely studied due to its surface lowering,calving,and warming.In this study,we combined multisource remote-sensing data,calculated the long-term series of surface ...The stability of the Larsen C Ice Shelf(LIS)has been widely studied due to its surface lowering,calving,and warming.In this study,we combined multisource remote-sensing data,calculated the long-term series of surface elevation above basal channels and basal melt rate,and analyzed the dynamic changes in the LIS before and after calving in 2017.We found that the basal channels were mainly concentrated in the southern LIS,and the basal melt rate was higher in the south.The Weddell Sea warm water mass entered the bottom of the LIS through the sea trough and promoted basal melting.There was an abnormal basal channel where changes in sea ice concentrations caused by wind-driven currents led to abnormal development.We did not observe significant changes in ice thickness,ice velocity and strain rate in the short term before and after the great calving in 2017.However,the basal melt rate was mainly influenced by the sea ice extent in front of the LIS from 2010 to 2020.Changes in the sea ice extent indirectly altered the proportion of High Salinity Shelf Water(HSSW)entering the ice shelf bottom water mass,which in turn promoted(or inhibited)basal melting of the LIS.In other words,we found no evidence for any dynamic changes in the LIS before and after the great calving in 2017.Since the calving area was within the Passive Shelf Ice(PSI),we have also provided additional evidence for the existence of the PSI.In addition,we speculate that the impact of calving on the LIS will not be visible in the short term,so we need to continuously observe the subsequent dynamic changes in the LIS.展开更多
The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Al...The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Although slaughtering a great number of calves during the late September and early October do bring about relatively higher calving rate that is mos yak cowst can give 3,4,5 and 6calves during 4,5,6 and 7 years old respectively. This makes major calving months shift from April or May to June.展开更多
Basal melting and calving are the main pathways for mass loss in Antarctic ice shelves.Basal channels,as detailed variations in basal melting,mutually promote basal melting and calving,thereby weakening the stability ...Basal melting and calving are the main pathways for mass loss in Antarctic ice shelves.Basal channels,as detailed variations in basal melting,mutually promote basal melting and calving,thereby weakening the stability of ice shelves.Therefore,it is necessary to calculate and statistically analyze basal melting,basal channels,and calving events across all Antarctic ice shelves and examine the correlation among these three factors.This study utilizes various data sources to calculate the Basal Channel Density(BCD)and average basal melt rate of all Antarctic ice shelves during 2010-2020,as well as the spatial correlation between basal melting,basal channels,and calving.We found that ice shelves along the Amundsen Sea and Bellingshausen Sea have higher basal melt rates and basal channel densities,while other sea areas have lower values.This is mainly influenced by seabed topography and Circumpolar Deep Water.Excluding(CDW)extreme calving events,there is a positive correlation among basal melting,basal channels,and calving in coastal ice shelves across different sea areas,with a correlation coefficient exceeding 0.67.This indicates that basal melting and basal channels are major factors causing ice shelf calving.Our results emphasize the importance of the impact of basal melting,basal channels,and calving on ice shelf stability,and they provide a significant reference for further research on ice shelf-ocean interactions.展开更多
The bovine embryos used for nonsurgical transfer should be morulae or blastocysts which are generally obtained from donor cow through superovulation and insemination. Due to the high cost of the embryos, the spread of...The bovine embryos used for nonsurgical transfer should be morulae or blastocysts which are generally obtained from donor cow through superovulation and insemination. Due to the high cost of the embryos, the spread of embryo transfer is influenced to certain extent. In recent years, in vitro fertilization (IVF)technique has been adopted abroad to expand the source of embryos. The methods employed normally were culturing the embryos in rabbit’s or sheep’s oviducts (in vivo culture) to overcome '8—16-cell block', the morula or blastocyst developed in vivo was recovered and then transferred to recipients. However, the research concerning in vitro culture of IVF ova to the morula-blastocvst stage was展开更多
Geographical barriers and distance can reduce gene exchange among animals,resulting in genetic divergence of geographically isolated populations.The Tibetan antelope(Pantholops hodgsonii)has a geographical range of ap...Geographical barriers and distance can reduce gene exchange among animals,resulting in genetic divergence of geographically isolated populations.The Tibetan antelope(Pantholops hodgsonii)has a geographical range of approximately 1600 km across the Qinghai-Tibet Plateau,which comprises a series of tall mountains and big rivers.However,previous studies indicate that there is little genetic differentiation among their geographically delineated populations.To better understand the genetic structure of P.hodgsonii populations,we collected 145 samples from the 3 major calving regions,taking into consideration their various calving grounds and migration routes.We used a combination of mitochondrial sequences(Cyt b,ATPase,D-loop and COX I)to investigate the genetic structure and the evolutionary divergence of the populations.Significant,albeit weak,genetic differentiation was detected among the 3 geographical populations.Analysis of the genetic divergence process revealed that the animals gradually entered a period of rapid genetic differentiation approximately 60000 years ago.The calving migration of P.hodgsonii cannot be the main cause of their weak genetic structure because this cannot fully homogenize the genetic pool.Instead,the geological and climatic events as well as the coupling vegetation succession process during this period have been suggested to greatly contribute to the genetic structure and the expansion of genetic diversity.展开更多
Group living is widespread across diverse taxa,and the mechanisms underlying collective decision-making in contexts of variable role division are critical for understanding the dynamics of group stability.While studie...Group living is widespread across diverse taxa,and the mechanisms underlying collective decision-making in contexts of variable role division are critical for understanding the dynamics of group stability.While studies on collective behavior in small animals such as fish and insects are well-established,similar research on large wild animals remains challenging due to the limited availability of sufficient and systematic field data.Here,we aimed to explore the collective decision-making pattern and its sexual difference for the dimorphic Tibetan antelopes Pantholops hodgsonii(chiru)in Xizang Autonomous Region,China,by analyzing individual leadership distribution,as well as the joining process,considering factors such as calving stages and joining ranks.The distinct correlations of decision participants’ratio with group size and decision duration underscore the trade-off between accuracy and speed in decision-making.Male antelopes display a more democratic decision-making pattern,while females exhibit more prompt responses after calving at an early stage.This study uncovers a partially shared decision-making strategy among Tibetan antelopes,suggesting flexible self-organization in group decision processes aligned with animal life cycle progression.展开更多
Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue ...Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue by ～ 27 km.Further,in July 2012,another 10 km was lost through calving.In order to understand these events in perspective,here the authors perform a long-term data analysis of Petermann Glacier calving-front variability and ice velocity for each year in the 1990s-2000s,supplemented by available observations from the previous three decades.Five major （on the order of 100 krm2） calving events are identified,with ～ 153 km2 calved from 1959 to 1961,～ 168 km2 in 1991,～ 71 km2 in 2001,～ 270 km2 in 2010,and ～ 130 km2 in 2012-as well as ～ 31 k m2 calved in 2008.The increased frequency of major calving events in recent years has left the front terminus position retreated nearly 25 km beyond the range of observed in previous decades.In contrast,stable ice-dynamics are suggested from ice-velocity measurements made each year between 1993-2012,which are on average 1063 m yr-1,with limited interannual variability and no significant trend; moreover,there is no apparent relationship between ice-velocity variability and calving events.The degree to which the massive calving events in 2010 and 2012 represent natural episodic variability or a response to atmospheric and/or oceanic changes remains speculative; however,melt-induced weakening of the floating ice tongue in recent years is strongly suggested.展开更多
The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 t...The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk （DIM） of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies.展开更多
文摘Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of records of 2496 Chinese Holsteins first lactation cows collected from 1989 to 2000.The model included 21 herd effects,four calving season effects,nine age at first calving effects,6697 animal effects.(Co)variance components of milk yield,fat yield and age at first calving were estimated with the software package for variance component estimation(VCE) by an animal model. The heritabilities were 0.14,0.21,0.38 for milk yield,fat yield and age at first calving,respectively.The estimates of genetic correlation between milk yield and fat yield,age at first calving were 0.96,-0.29,respectively.The estimate of genetic correlation between fat yield and age at first calving was -0.28.
基金The National Key Research and Development Program of China under contract Nos 2016YFC1402704 and2016YFC1401007the International Science and Technology Cooperation Project of China under contract No.2011DFA22260
文摘A massive iceberg, named A-68 by National Ice Center （NIC） officially, calved away from the Larsen C Ice Shelf in Antarctica on luly 12, 2017. The iceberg A-68 is about 5 800 km2, weighs more than a trillion tons and it is one of the biggest ever recorded icebergs. Chinese satellites Gaofen-1 （GF-1） and Gaofen-3 （GF-3） data was used to monitoring the propagation of the rift and the iceberg by National Satellite Ocean Application Service （NSOAS）.
文摘Age at first calving (AFC) affects the profitability of dairy enterprises. This study examined the relationships between AFC and subsequent fertility, milk production and survival up to third calving in UK Holstein-Friesian heifers;Study 1 comprised 134 consecutively born heifers from the same herd (AFC 764 ± 8 days) and Study 2 contained 445 heifers born on 17 farms (AFC 796 ± 6 days). Growth rates and fertility during rearing were monitored and animals were subsequently divided into four AFC groups for analysis: <23 months, 23 - 25 months, 26 - 30 months and >30 months. The actual AFC reflected both growth rate and heifer fertility, with later calving heifers already lighter by 6 months of age. The proportion conceiving to first service was highest (93% and 84% for Studies 1 and 2, respectively) for the youngest AFC group. Fertility in the first lactation was best in cows calving at 23 - 25 months and worst in the oldest AFC group. Milk production parameters in the first and second lactations were broadly similar between AFC groups but significantly more heifers with an AFC < 26 months calved for a third time. These younger calving animals therefore achieved more days in milk over 5 years, with >44% of their days alive spent in milk production compared with only 18% - 40% in cows calving at ≥26 months. Hence cows with an AFC < 26 months produced the most milk in their first 5 years of life. These results indicate that an AFC of 0.75 kg/d up to 15 months and good heifer fertility and resulted in the best subsequent performance.
基金The National Key R&D Program of China under contract Nos 2018YFA0605902,2016YFC1402705,2016YFC1402706 and 2016YFC1401505the National Natural Science Foundation of China under contract Nos 41576179 and 51639004+1 种基金the fund of Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership under contract No.SR140300001the China Postdoctoral Science Foundation under contract No.2020M670746.
文摘Mass loss caused by glacier calving is one of the direct contributors to global sea level rise.Reliable calving laws are required for accurate modelling of ice sheet mass balance.Both continuous and discontinuous methods have been used for glacial calving simulations.In this study,the discrete element method(DEM)based on dilated polyhedral elements is introduced to simulate the calving process of a tidewater glacier.Dilated polyhedrons can be obtained from the Minkowski sum of a sphere and a core polyhedron.These elements can be utilized to generate a continuum ice material,where the interaction force between adjacent elements is modeled by constructing bonds at the joints of the common faces.A hybrid fracture model considering fracture energy is introduced.The viscous creep behavior of glaciers on long-term scales is not considered.By applying buoyancy and gravity to the modelled glacier,DEM results show that the calving process is caused by cracks which are initialized at the top of the glacier and spread to the bottom.The results demonstrate the feasibility of using the dilated polyhedral DEM method in glacier simulations,additionally allowing the fragment size of the breaking fragments to be counted.The relationship between crack propagation and internal stress in the glacier is analyzed during calving process.Through the analysis of the Mises stress and the normal stress between the elements,it is found that geometric changes caused by the glacier calving lead to the redistribution of the stress.The tensile stress between the elements is the main influencing factor of glacier ice failure.In addition,the element shape,glacier base friction and buoyancy are studied,the results show that the glacier model based on the dilated polyhedral DEM is sensitive to the above conditions.
文摘This study was conducted to estimate variance components and genetic parameters for 305 days mature equivalent milk yields (MEM) and calving interval (CAI) of registered Xinjiang Brown cattle. The total records were 3940 including 2579 for 305-day MEM and 1970 for CAI, which were collected from Xinjiang Urumqi Cattle Breeding farm in China with calving records from 1990 to 2008. Genetic parameters were obtained by multiple trait derivative-free restricted maximum likelihood (MTDFREML) using animal model. The model included year, season, parity and calving interval of calving for 305 days MEM, and year, season and parity of birth for CAI as fixed effects. Heritability for 305 days MEM was moderate (0.39) and in the same range of parameters estimated in management systems with medium production levels. Heritability of calving interval was small (0.02) as fertility traits for Xinjiang Brown cattle. Estimates of genetic and environmental correlations between 305 days MEM and CAI were 0.47 and 0.37, respectively. Estimates of genetic variation and heritability indicated that selection would result in genetic improvement of production traits. Estimates of both heritability and genetic variation for CAI were small, which indicates that genetic improvement would be difficult.
文摘A total of 5852 records concerning daily milk yield, content of protein and fat, and somatic cell count was recorded in two farms (organic and conventional). Somatic cell count was log10- transformed before analysis because was not normally distributed. The mixed model methodology was used according to a repeated-measures scheme, as the restricted maximum likelihood method to estimate lactation curves at different season of calving and at different calving order. Calving order affected milk yield only in the first three calving order with the lowest production levels in the first six months of the year for both farm;no effect could be observed on fat and protein contents. The organic farm shows the minor milk production (7.77 vs8.10 kg/day/head organic and traditional respectively), but good qualitative characteristics of milk, and minor content of Somatic Cell Count. The milk production is major, in traditional farm, in summer respect the winter (10.4 vs6.34 kgof milk/day/ head). In biological farm no difference between seasons were observed. Peak milk yield occurs, for both farms, at around the 6th - 7th wk of lactation.
文摘The SNIT theory proposes the effects of exploding stars,supernova and nova,on the biosphere of Earth.The feature on our planet that is most sensitive to the incoming energy of an exploding star is sea ice at the poles and this brings in the concept of global warming.The incoming particle streams for SN 1054,SN 1006,and Nova WZ Sagittae have left easily interpreted data noted as calving under the Antarctic ice cap that matches previously predicted longitude locations for the local heat input of the particle streams of the exploding stars.Animal die offs are also caused by the incoming particle streams.The deflection area longitude range for SN 1054 calving produces the correct longitude range for the moose die off beginning in the northern USA in 2006.Some Martian dust storms are created by the wave front of the exploding star debris streams.The explanation of these exploding stars effects using the SNIT theory is the object of this work.
文摘Good management of the pregnant heifer is crucial to ensure that she is well grown and healthy and calves down easily before joining the milking herd. This study collected primary data on all aspects of heifer management on 101 UK farms during heifer pregnancy from conception to calving including farm factors and associated costs of system inputs. A cost analysis workbook was developed to calculate the cost of rearing per heifer for each of the study farms. Associations between cost of rearing and farms factors were determined using linear regression and analysis of variance. Heifers had a mean age of conception of 509 d (range 365 - 700 d) and an age at first calving of 784 d (range 639 - 973 d). The mean total cost of rearing during pregnancy was ￡450.36 (range ￡153.11 to ￡784.00) with a mean daily cost of ￡1.64 (range ￡0.56 to ￡2.86). The inputs contributing the most to cost were feed (32.7%), labour (23.8%) and slurry disposal (11.2%). Total purchased and homegrown feed and grazing contributed between 25.5% and 65.4% of total costs with a mean contribution of 43.6%. The cost of rearing was lowest in spring calving herds and highest in all year round calving herds with intermediate values in autumn and multi block calving herds. The main variables influencing the cost were the number of days spent at grass, age at first calving, calving pattern, breed, herd size and region. Each extra day in age at first calving increased the mean cost of rearing during pregnancy by ￡0.33/d whereas every extra day at grass reduced the cost by ￡1.75/d.
文摘The objective of this study was to evaluate the relationship of the calving number with productive indicators in Nelore cows in a grazing system in the Bolivian tropics.Retrospective data,corresponding to the period between 1991 and 2019 referred to 1,566 primiparous and multiparous Nelore breed cows were used.A decrease in the total number of animals was observed from the first to the fifth calving,it was also observed that the age of the first calving was similar in all cows without significant differences,showing that longevity is not associated with the age at the first calving.Live weight presented significant differences(p≤0.05),according to the number of calvings;the fourth and fifth calving cows are the heaviest.Weight of calf at birth did not show a relationship with the number of calvings either.However,it does so in the weight of calf at weaning,which increases from the first to the fifth calving with significant differences(p≤0.05).There were significant differences(p≤0.05)for the interval between calvings,decreasing as the calvings progressed.It is concluded that there is a relationship between the number of calving with productive indicators in Nelore cows in a grazing system in the Bolivian tropics,fundamentally those efficiency variables where longevity is important.
文摘Most probable producing ability （MPPA） is the one factor used to compare the performance potential of dam based on the data of their progeny. The purpose of the research was to study the genetic ability of weaning weight, yearling weight and calving interval of Bali cows. The weaning weight data of 296 cows derived from 99 dams, yearling weight data of 245 cows derived from 86 dams and cabAng interval data of 194 cows from 63 dams were used to estimate repeatability and MPPA of Bali cows in a herd for the three traits. Repeatability of three traits was estimated by analysis of intra-class correlation, and these in turn were used for calculating the estimated MPPA of cows. The results showed that the means of weaning weight of males and females were 95.56 ± 17.25 kg and 87.57 ± 18.45 kg, respectively; means of yearling weight were 143.39 ±25.78 kg and 136.90 ± 22.01 kg, respectively; and mean calving interval was 391.62±22.59 d. The estimated repeatability of weaning weight, yearling weight and calving interval were 0.006 ±0.059, 0.022 ± 0.068 and 0.115 ± 0.078, respectively. The best 10 dams in the herd based on the estimates of MPPA for weaning weight, yearling weight and calving interval were not the same for the three traits.
基金supported by The National Natural Science Foundation of China[grant number 41941010 and 42006184]State Key Laboratory of Cryospheric Science,Northwest Institute of Eco-Environment and Resources,Chinese Academy Sciences[grant number SKLCS-OP-2021-07]the Fundamental Research Funds for the Central Universities[grant number 2042022kf1068].We thank S.R.M.Ligtenberg for providing IMAU-FDM.
文摘The stability of the Larsen C Ice Shelf(LIS)has been widely studied due to its surface lowering,calving,and warming.In this study,we combined multisource remote-sensing data,calculated the long-term series of surface elevation above basal channels and basal melt rate,and analyzed the dynamic changes in the LIS before and after calving in 2017.We found that the basal channels were mainly concentrated in the southern LIS,and the basal melt rate was higher in the south.The Weddell Sea warm water mass entered the bottom of the LIS through the sea trough and promoted basal melting.There was an abnormal basal channel where changes in sea ice concentrations caused by wind-driven currents led to abnormal development.We did not observe significant changes in ice thickness,ice velocity and strain rate in the short term before and after the great calving in 2017.However,the basal melt rate was mainly influenced by the sea ice extent in front of the LIS from 2010 to 2020.Changes in the sea ice extent indirectly altered the proportion of High Salinity Shelf Water(HSSW)entering the ice shelf bottom water mass,which in turn promoted(or inhibited)basal melting of the LIS.In other words,we found no evidence for any dynamic changes in the LIS before and after the great calving in 2017.Since the calving area was within the Passive Shelf Ice(PSI),we have also provided additional evidence for the existence of the PSI.In addition,we speculate that the impact of calving on the LIS will not be visible in the short term,so we need to continuously observe the subsequent dynamic changes in the LIS.
文摘The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Although slaughtering a great number of calves during the late September and early October do bring about relatively higher calving rate that is mos yak cowst can give 3,4,5 and 6calves during 4,5,6 and 7 years old respectively. This makes major calving months shift from April or May to June.
基金The National Natural Science Foundation of China No.42406251the Fundamental Research Funds for the Central Universities under contract No.2042025kf0079 and 2042025kf0080+2 种基金the Postdoctoral Fellowship Program of CPSF under contract No.GZC20241257the Postdoctoral Fellowship Program of CPSF under contract No.GZC20241257the Key Laboratory of Polar Environment Monitoring and Public Governance(Wuhan University),the Ministry of Education Open Fund under contract Nos 202403 and 202405.
文摘Basal melting and calving are the main pathways for mass loss in Antarctic ice shelves.Basal channels,as detailed variations in basal melting,mutually promote basal melting and calving,thereby weakening the stability of ice shelves.Therefore,it is necessary to calculate and statistically analyze basal melting,basal channels,and calving events across all Antarctic ice shelves and examine the correlation among these three factors.This study utilizes various data sources to calculate the Basal Channel Density(BCD)and average basal melt rate of all Antarctic ice shelves during 2010-2020,as well as the spatial correlation between basal melting,basal channels,and calving.We found that ice shelves along the Amundsen Sea and Bellingshausen Sea have higher basal melt rates and basal channel densities,while other sea areas have lower values.This is mainly influenced by seabed topography and Circumpolar Deep Water.Excluding(CDW)extreme calving events,there is a positive correlation among basal melting,basal channels,and calving in coastal ice shelves across different sea areas,with a correlation coefficient exceeding 0.67.This indicates that basal melting and basal channels are major factors causing ice shelf calving.Our results emphasize the importance of the impact of basal melting,basal channels,and calving on ice shelf stability,and they provide a significant reference for further research on ice shelf-ocean interactions.
文摘The bovine embryos used for nonsurgical transfer should be morulae or blastocysts which are generally obtained from donor cow through superovulation and insemination. Due to the high cost of the embryos, the spread of embryo transfer is influenced to certain extent. In recent years, in vitro fertilization (IVF)technique has been adopted abroad to expand the source of embryos. The methods employed normally were culturing the embryos in rabbit’s or sheep’s oviducts (in vivo culture) to overcome '8—16-cell block', the morula or blastocyst developed in vivo was recovered and then transferred to recipients. However, the research concerning in vitro culture of IVF ova to the morula-blastocvst stage was
基金The Strategic Priority Research Program of the Chinese Academy of Sciences(XDA23060602,XDA2002030302)Construction Fund for Qinghai Provincial Key Laboratories(2017-ZJ-Y23).
文摘Geographical barriers and distance can reduce gene exchange among animals,resulting in genetic divergence of geographically isolated populations.The Tibetan antelope(Pantholops hodgsonii)has a geographical range of approximately 1600 km across the Qinghai-Tibet Plateau,which comprises a series of tall mountains and big rivers.However,previous studies indicate that there is little genetic differentiation among their geographically delineated populations.To better understand the genetic structure of P.hodgsonii populations,we collected 145 samples from the 3 major calving regions,taking into consideration their various calving grounds and migration routes.We used a combination of mitochondrial sequences(Cyt b,ATPase,D-loop and COX I)to investigate the genetic structure and the evolutionary divergence of the populations.Significant,albeit weak,genetic differentiation was detected among the 3 geographical populations.Analysis of the genetic divergence process revealed that the animals gradually entered a period of rapid genetic differentiation approximately 60000 years ago.The calving migration of P.hodgsonii cannot be the main cause of their weak genetic structure because this cannot fully homogenize the genetic pool.Instead,the geological and climatic events as well as the coupling vegetation succession process during this period have been suggested to greatly contribute to the genetic structure and the expansion of genetic diversity.
基金supported by the National Natural Science Foundation of China(Grant no.32101237)the China Postdoctoral Science Foundation(Grant no.2021M691522)+1 种基金the National Key Research and Development Program(Grant no.2022YFC3202104)the Tibet Major Science and Technology Project(Grant no.XZ201901-GA-06).
文摘Group living is widespread across diverse taxa,and the mechanisms underlying collective decision-making in contexts of variable role division are critical for understanding the dynamics of group stability.While studies on collective behavior in small animals such as fish and insects are well-established,similar research on large wild animals remains challenging due to the limited availability of sufficient and systematic field data.Here,we aimed to explore the collective decision-making pattern and its sexual difference for the dimorphic Tibetan antelopes Pantholops hodgsonii(chiru)in Xizang Autonomous Region,China,by analyzing individual leadership distribution,as well as the joining process,considering factors such as calving stages and joining ranks.The distinct correlations of decision participants’ratio with group size and decision duration underscore the trade-off between accuracy and speed in decision-making.Male antelopes display a more democratic decision-making pattern,while females exhibit more prompt responses after calving at an early stage.This study uncovers a partially shared decision-making strategy among Tibetan antelopes,suggesting flexible self-organization in group decision processes aligned with animal life cycle progression.
基金supported by the Trond Mohn Donation to the Mohn-Sverdrup Center at the Nansen Center,the Research Council of Norway’s UK/Netherlands/Norway RAPID programthe project AWAKE under the Polish-Norwegian Research Fund(2009–2011)
文摘Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue by ～ 27 km.Further,in July 2012,another 10 km was lost through calving.In order to understand these events in perspective,here the authors perform a long-term data analysis of Petermann Glacier calving-front variability and ice velocity for each year in the 1990s-2000s,supplemented by available observations from the previous three decades.Five major （on the order of 100 krm2） calving events are identified,with ～ 153 km2 calved from 1959 to 1961,～ 168 km2 in 1991,～ 71 km2 in 2001,～ 270 km2 in 2010,and ～ 130 km2 in 2012-as well as ～ 31 k m2 calved in 2008.The increased frequency of major calving events in recent years has left the front terminus position retreated nearly 25 km beyond the range of observed in previous decades.In contrast,stable ice-dynamics are suggested from ice-velocity measurements made each year between 1993-2012,which are on average 1063 m yr-1,with limited interannual variability and no significant trend; moreover,there is no apparent relationship between ice-velocity variability and calving events.The degree to which the massive calving events in 2010 and 2012 represent natural episodic variability or a response to atmospheric and/or oceanic changes remains speculative; however,melt-induced weakening of the floating ice tongue in recent years is strongly suggested.
基金Supported by Science and Technology Open Cooperation Project of Henan Province(162106000017)Science and Technology People-benefiting Plan Project of Henan Province(152207110004)Puyang Science and Technology Plan Project(150109)~~
文摘The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk （DIM） of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies.
