Most measurements for beef improvement in South Africa are per individual (weaning weight, calving interval, growth rate, etc.). A measurement that expresses performance per constant unit, e.g. kilogram calf weaned pe...Most measurements for beef improvement in South Africa are per individual (weaning weight, calving interval, growth rate, etc.). A measurement that expresses performance per constant unit, e.g. kilogram calf weaned per Large Stock Unit (LSU) can eventually be translated to kilogram calf produced per kg CO2 equivalent. A LSU is defined as a bovine requiring 75 MJ Metabolisable Energy (ME) per day. If more kilogram weaner calf can be produced per LSU (KgC/LSU), the carbon footprint of beef can be reduced. This study used breed average values to investigate the KgC/LSU for the 30 beef and dual purpose breeds in South Africa. The breeds were categorized in the following breed types: Sanga (indigenous to South Africa) Sanga derived, Zebu, Zebu derived, British and European. No relationship was found between cow weights and KgC/LSU, indicating that it is independent of cow weight between breeds. However, when the data is summarized into breed types, the Sanga and European breed types produce the least KgC/ LSU and Sanga derived breed types the most. This high value of the Sanga derived breeds is probably due to retained heterosis. Composite breeds are mostly intermediate to parental breeds for individual traits but superior for composite traits and KgC/LSU is a composite trait. These calculations were only done on breed averages. A genetic analysis on a breed level to estimate genetic parameters for this trait, and its genetic correlations with other traits now needs to be done before a decision can be taken whether selection for KgC/LSU will be feasible. The ultimate aim with a trait like this is to reduce the carbon footprint of weaner calf production since more kilogram calf will be produced per LSU (constant feed unit).展开更多
Developing countries from the southern hemisphere will be confronted by the same beef production challenges caused by global warming, because these countries are at the same geographical positions in southern latitude...Developing countries from the southern hemisphere will be confronted by the same beef production challenges caused by global warming, because these countries are at the same geographical positions in southern latitudes. Global warming is expected to have a more extreme effect on the southern hemisphere than on other continents and will have a negative effect on the beef production environments in these countries. The negative effects will include high ambient temperatures, nutritional stress and altered patterns of animal diseases. Heat stress in beef cattle on veld/savannah is expected to increase as a result of changing weather patterns on a global and regional scale. This may negatively influence food production from beef cattle for the human food chain. Negative effects of increased temperatures and thus heat stress can include lower reproductive rates and weaning weights. The effect of heat stress can be partly addressed by nutritional strategies, such as replacing rapid fermentable carbohydrates with saturated fatty acids and the feeding of more by-pass protein and dietary electrolytes. Global warming will also alter the distribution pattern of animal diseases and the vectors of some of these diseases. This may even include the spread to South American countries. Likewise the nutritional value of natural pastures may be influenced. The effect of global warming on the quality of pastures will depend on whether the global warming is a result of increased carbon dioxide levels or not. An improved understanding of the adaptation of beef cattle to their production environments is important, but adaptation is complex and thus difficult to measure. Fortunately, several proxy-indicators for adaptation such as reproductive, production and health traits are available. The selection of animals and genotypes that are better adapted to the production system, including heat stress, is possible and should be persuade to ensure sustainable beef production in hotter climates.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 studied.展开更多
文摘Most measurements for beef improvement in South Africa are per individual (weaning weight, calving interval, growth rate, etc.). A measurement that expresses performance per constant unit, e.g. kilogram calf weaned per Large Stock Unit (LSU) can eventually be translated to kilogram calf produced per kg CO2 equivalent. A LSU is defined as a bovine requiring 75 MJ Metabolisable Energy (ME) per day. If more kilogram weaner calf can be produced per LSU (KgC/LSU), the carbon footprint of beef can be reduced. This study used breed average values to investigate the KgC/LSU for the 30 beef and dual purpose breeds in South Africa. The breeds were categorized in the following breed types: Sanga (indigenous to South Africa) Sanga derived, Zebu, Zebu derived, British and European. No relationship was found between cow weights and KgC/LSU, indicating that it is independent of cow weight between breeds. However, when the data is summarized into breed types, the Sanga and European breed types produce the least KgC/ LSU and Sanga derived breed types the most. This high value of the Sanga derived breeds is probably due to retained heterosis. Composite breeds are mostly intermediate to parental breeds for individual traits but superior for composite traits and KgC/LSU is a composite trait. These calculations were only done on breed averages. A genetic analysis on a breed level to estimate genetic parameters for this trait, and its genetic correlations with other traits now needs to be done before a decision can be taken whether selection for KgC/LSU will be feasible. The ultimate aim with a trait like this is to reduce the carbon footprint of weaner calf production since more kilogram calf will be produced per LSU (constant feed unit).
文摘Developing countries from the southern hemisphere will be confronted by the same beef production challenges caused by global warming, because these countries are at the same geographical positions in southern latitudes. Global warming is expected to have a more extreme effect on the southern hemisphere than on other continents and will have a negative effect on the beef production environments in these countries. The negative effects will include high ambient temperatures, nutritional stress and altered patterns of animal diseases. Heat stress in beef cattle on veld/savannah is expected to increase as a result of changing weather patterns on a global and regional scale. This may negatively influence food production from beef cattle for the human food chain. Negative effects of increased temperatures and thus heat stress can include lower reproductive rates and weaning weights. The effect of heat stress can be partly addressed by nutritional strategies, such as replacing rapid fermentable carbohydrates with saturated fatty acids and the feeding of more by-pass protein and dietary electrolytes. Global warming will also alter the distribution pattern of animal diseases and the vectors of some of these diseases. This may even include the spread to South American countries. Likewise the nutritional value of natural pastures may be influenced. The effect of global warming on the quality of pastures will depend on whether the global warming is a result of increased carbon dioxide levels or not. An improved understanding of the adaptation of beef cattle to their production environments is important, but adaptation is complex and thus difficult to measure. Fortunately, several proxy-indicators for adaptation such as reproductive, production and health traits are available. The selection of animals and genotypes that are better adapted to the production system, including heat stress, is possible and should be persuade to ensure sustainable beef production in hotter climates.
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 studied.
