BEEF COW EFFICIENCY

Authors: JENKINS, THOMAS; FERRELL, CALVIN

Submitted to: Book Chapter
Publication Type: Other
Publication Acceptance Date: 8/1/2003
Publication Date: N/A
Citation: N/A

Interpretive Summary: Variation exists among cattle populations to improve the conversion of feed resources to a final product. A biologically efficient cow is one producing a calf each year she remains in the cowherd. The nutrition-reproduction axis may influence this success. Energy expenditure for maintenance may effect the reproduction of the cow. Energy expenditure for maintenance appears to be correlated to genetic potential for mature size and lactation. At restricted feed availability, an increase in maintenance efficiency among breeds with greater potential for size can be associated with longer postpartum periods for mature cows resulting in lower reproductive rate thus lowering cow efficiency. At lower intakes, variation exists among breeds for expression of milk production among higher milk producing breeds resulting in lowered efficiency of gain for calves with higher growth potential. Sufficient additive variation exists to alter fasting heat production in cattle, and selection criteria are being evaluated that allow "non-productive" energy expenditures to be reduced. More information to clarify the definition of an efficient cow, selection protocol, and potential correlated responses is needed. Genotype by environment interaction (abundant vs sparse nutritional testing environment) potential effects on cow efficiency requires investigations. Rather than seeking to reduce energy requirements for maintenance, perhaps stabilizing these requirements over a wide range of nutritional scenarios is more desirable. Enhancing an animal's genetic potential to conserve energy under sparse energy environments (feed resources and/or body fat) could be counterproductive to developing an efficient cow. Do other approaches to improving cow efficiency exist? With genomic information increasing every day, what phenotypes can we measure to associate with bovine gene map? Using genomics information, will we be able to identify heifers that are well suited to producing a calf every year within a defined production environment? An efficient cow for one producer may be ineffective under a different management program.

Technical Abstract: Variation exists among cattle populations to improve the conversion of feed resources to a final product. A biologically efficient cow is one producing a calf each year she remains in the cowherd. The nutrition-reproduction axis may influence this success. Energy expenditure for maintenance may effect the reproduction of the cow. Energy expenditure for maintenance appears to be correlated to genetic potential for mature size and lactation. At restricted feed availability, an increase in maintenance efficiency among breeds with greater potential for size can be associated with longer postpartum periods for mature cows resulting in lower reproductive rate thus lowering cow efficiency. At lower intakes, variation exists among breeds for expression of milk production among higher milk producing breeds resulting in lowered efficiency of gain for calves with higher growth potential. Sufficient additive variation exists to alter fasting heat production in cattle, and selection criteria are being evaluated that allow "non-productive" energy expenditures to be reduced. More information to clarify the definition of an efficient cow, selection protocol, and potential correlated responses is needed. Genotype by environment interaction (abundant vs sparse nutritional testing environment) potential effects on cow efficiency requires investigations. Rather than seeking to reduce energy requirements for maintenance, perhaps stabilizing these requirements over a wide range of nutritional scenarios is more desirable. Enhancing an animal's genetic potential to conserve energy under sparse energy environments (feed resources and/or body fat) could be counterproductive to developing an efficient cow. Do other approaches to improving cow efficiency exist? With genomic information increasing every day, what phenotypes can we measure to associate with bovine gene map? Using genomics information, will we be able to identify heifers that are well suited to producing a calf every year within a defined production environment? An efficient cow for one producer may be ineffective under a different management program.