Dairy heifers only start to produce a return on investment at first calving. The length of the non-productive rearing period is largely governed by farmer decisions on plane of nutrition and reproduction management. P...Dairy heifers only start to produce a return on investment at first calving. The length of the non-productive rearing period is largely governed by farmer decisions on plane of nutrition and reproduction management. Primary data were collected from 101 dairy farms and a cost analysis workbook developed to calculate individual inputs in each of three periods to determine which management decisions and farm factors have the greatest influence on the total costs associated with rearing. This paper covers weaning until conception. Heifers were weaned at 62 d (range 42 - 112 d) and conceived by 509 d (range 365 - 700 d) giving an average weaning to conception period of 447 ± 60 d (range 253 to 630 d). The mean daily cost of rearing during this period was ￡1.65 (range ￡0.75 to ￡2.97 on different farms) giving a mean total cost of ￡745.94 per heifer (range ￡295.32 to ￡1745.85). This large variation was mostly due to the duration, which was mainly determined by age at first breeding (mean 476 days, range 365 - 700 d). The main contributors to total costs were feed (35.6%), labour (24.7%) and bedding (8.9%). The variables most strongly associated with the total costs were age at conception, calving pattern and breed. A multivariable model predicted an increase in mean cost of ￡2.26 for each extra day in age at conception. The total cost was highest in herds with all year round calving, intermediate in multi-block and lowest in spring and autumn calving herds, with Friesian x and Jersey herds having the lowest cost of rearing.展开更多
[Objectives]This study was conducted to develop a molecular marker immunomagnetic bead sorting technology method that can specifically identify dead spermatozoa.[Methods]This study first confirmed the specific binding...[Objectives]This study was conducted to develop a molecular marker immunomagnetic bead sorting technology method that can specifically identify dead spermatozoa.[Methods]This study first confirmed the specific binding of Annexin V to dead bovine spermatozoa,and tried to remove dead spermatozoa in semen combining with the immunomagnetic bead technology,so as to improve the separation efficiency of target spermatozoa in the process of sex-controlled semen preparation on a flow cytometer.[Results]The spermatozoon motility,membrane integrity and mitochondrial activity after sorting and the rate of dead spermatozoa during the on-machine X/Y separation were all improved to different degrees(P<0.05),indicating that the technical process design could effectively remove some dead spermatozoa,and there was no significant effect on frozen sexed semen prepared from the separated X or Y spermatozoa(P>0.05),indicating that the technical process did not cause additional damage to the spermatozoa.[Conclusions]Combining the specificity of Annexin V with the immunomagnetic bead method could effectively remove dead spermatozoa from bovine spermatozoa,and significantly reduce the rate of dead spermatozoa in bovine permatozoa during sex-controlled separation(P<0.05).The method developed can effectively improve the production efficiency of frozen sexed semen of dairy cows,reduce the production cost,and promote the industrial application of the product.展开更多
Livestock production impacts food security of developing countries, especially where efficiency of production is compromised by environmental stressors. In South Africa, breeding with indigenous Afrikaner cattle that ...Livestock production impacts food security of developing countries, especially where efficiency of production is compromised by environmental stressors. In South Africa, breeding with indigenous Afrikaner cattle that are genetically well adapted to subtropical environments is considered an essential strategy for sustainable beef production. Today, there is a potential for farmers to participate in commercial systems that join adapted Afrikaner germplasm, used in a specialized maternal role, with exotic terminal sires to optimize production. The objective of this study was to assess productivity of five simulated production systems: 1) straightbred Afrikaner mated naturally, 2) a straight-bred Afrikaner cow herd with two sections;one section to produce replacement females and the other to cross with Charolais terminal sires, both using natural mating, 3) similar to 2, but applying sexed semen to produce replacement females, 4) similar to 2, but using a multi-breed composite dam line with a breed combination of 50% Afrikaner, 25% Hereford and 25% Simmental, and 5) similar to 4, but again applying sexed semen to produce replacement females. Parameter estimates needed to compare these systems were extracted from the scientific literature. Relative to straightbred Afrikaner dams, the simulated composite dams were more fit producing 7.8% more calves and their progeny performance was improved by reducing feed intake (-24.4%) and increasing meat production (+11.7%). The potential benefit of allocating more cows to the terminal sire was insufficient to offset the reduction in pregnancy rate that results with the use of sexed semen. Thus, system 4 had the greatest productivity (+23.1%) while requiring 22.8% less feed for finishing the progeny to be harvested relative to the purebred Afrikaner system. The combination of increased productivity and reduced feed requirement made use of a Charolais terminal sire in conjunction with multi-breed composite females bred by natural service the most efficient system among those studi展开更多
文摘Dairy heifers only start to produce a return on investment at first calving. The length of the non-productive rearing period is largely governed by farmer decisions on plane of nutrition and reproduction management. Primary data were collected from 101 dairy farms and a cost analysis workbook developed to calculate individual inputs in each of three periods to determine which management decisions and farm factors have the greatest influence on the total costs associated with rearing. This paper covers weaning until conception. Heifers were weaned at 62 d (range 42 - 112 d) and conceived by 509 d (range 365 - 700 d) giving an average weaning to conception period of 447 ± 60 d (range 253 to 630 d). The mean daily cost of rearing during this period was ￡1.65 (range ￡0.75 to ￡2.97 on different farms) giving a mean total cost of ￡745.94 per heifer (range ￡295.32 to ￡1745.85). This large variation was mostly due to the duration, which was mainly determined by age at first breeding (mean 476 days, range 365 - 700 d). The main contributors to total costs were feed (35.6%), labour (24.7%) and bedding (8.9%). The variables most strongly associated with the total costs were age at conception, calving pattern and breed. A multivariable model predicted an increase in mean cost of ￡2.26 for each extra day in age at conception. The total cost was highest in herds with all year round calving, intermediate in multi-block and lowest in spring and autumn calving herds, with Friesian x and Jersey herds having the lowest cost of rearing.
基金Supported by Targeted Poverty Alleviation Special Project of Hetao College(HYZX201955)Introduced Talent Scientific Research Start-up Fund of Hetao College(HYRC2019002)。
文摘[Objectives]This study was conducted to develop a molecular marker immunomagnetic bead sorting technology method that can specifically identify dead spermatozoa.[Methods]This study first confirmed the specific binding of Annexin V to dead bovine spermatozoa,and tried to remove dead spermatozoa in semen combining with the immunomagnetic bead technology,so as to improve the separation efficiency of target spermatozoa in the process of sex-controlled semen preparation on a flow cytometer.[Results]The spermatozoon motility,membrane integrity and mitochondrial activity after sorting and the rate of dead spermatozoa during the on-machine X/Y separation were all improved to different degrees(P<0.05),indicating that the technical process design could effectively remove some dead spermatozoa,and there was no significant effect on frozen sexed semen prepared from the separated X or Y spermatozoa(P>0.05),indicating that the technical process did not cause additional damage to the spermatozoa.[Conclusions]Combining the specificity of Annexin V with the immunomagnetic bead method could effectively remove dead spermatozoa from bovine spermatozoa,and significantly reduce the rate of dead spermatozoa in bovine permatozoa during sex-controlled separation(P<0.05).The method developed can effectively improve the production efficiency of frozen sexed semen of dairy cows,reduce the production cost,and promote the industrial application of the product.
文摘Livestock production impacts food security of developing countries, especially where efficiency of production is compromised by environmental stressors. In South Africa, breeding with indigenous Afrikaner cattle that are genetically well adapted to subtropical environments is considered an essential strategy for sustainable beef production. Today, there is a potential for farmers to participate in commercial systems that join adapted Afrikaner germplasm, used in a specialized maternal role, with exotic terminal sires to optimize production. The objective of this study was to assess productivity of five simulated production systems: 1) straightbred Afrikaner mated naturally, 2) a straight-bred Afrikaner cow herd with two sections;one section to produce replacement females and the other to cross with Charolais terminal sires, both using natural mating, 3) similar to 2, but applying sexed semen to produce replacement females, 4) similar to 2, but using a multi-breed composite dam line with a breed combination of 50% Afrikaner, 25% Hereford and 25% Simmental, and 5) similar to 4, but again applying sexed semen to produce replacement females. Parameter estimates needed to compare these systems were extracted from the scientific literature. Relative to straightbred Afrikaner dams, the simulated composite dams were more fit producing 7.8% more calves and their progeny performance was improved by reducing feed intake (-24.4%) and increasing meat production (+11.7%). The potential benefit of allocating more cows to the terminal sire was insufficient to offset the reduction in pregnancy rate that results with the use of sexed semen. Thus, system 4 had the greatest productivity (+23.1%) while requiring 22.8% less feed for finishing the progeny to be harvested relative to the purebred Afrikaner system. The combination of increased productivity and reduced feed requirement made use of a Charolais terminal sire in conjunction with multi-breed composite females bred by natural service the most efficient system among those studi
