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Stayability: Difference between revisions
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Stayability is generally defined as the probability of surviving to a specific age, given the opportunity to reach that age. Adapted to beef cows, the general definition of stayability is the probability of a cow surviving to her breakeven age, given the opportunity to reach that age. Cows usually need five consecutive calves by six years of age to generate enough income to pay their development and maintenance costs, so the age of six is was established as the target age for satiability. Without records of which females were retained for breeding and every calf they raised, cows with at least one calf before age six were considered to have opportunity, and successful cows had a calf at age 6 or older. Annual production records required by [[ Whole Herd Reporting | whole-herd reporting ]]systems enable more rigorous definitions of stayability. Calving first as a two-year-old can indicate opportunity, and a calf every year through age six may be required for success. | Stayability is generally defined as the probability of surviving to a specific age, given the opportunity to reach that age. Adapted to beef cows, the general definition of stayability is the probability of a cow surviving to her breakeven age, given the opportunity to reach that age. Cows usually need five consecutive calves by six years of age to generate enough income to pay their development and maintenance costs, so the age of six is was established as the target age for satiability. Without records of which females were retained for breeding and every calf they raised, cows with at least one calf before age six were considered to have opportunity, and successful cows had a calf at age 6 or older. Annual production records required by [[ Whole Herd Reporting | whole-herd reporting ]] systems enable more rigorous definitions of stayability. Calving first as a two-year-old can indicate opportunity, and a calf every year through age six may be required for success. | ||
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Contemporary groups for stayability should include all females entering the breeding herd with the same opportunity to stay. Basically, heifers | |||
===Genetic Evaluation=== | ===Genetic Evaluation=== | ||
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Revision as of 14:01, 31 October 2019
Stayability is generally defined as the probability of surviving to a specific age, given the opportunity to reach that age. Adapted to beef cows, the general definition of stayability is the probability of a cow surviving to her breakeven age, given the opportunity to reach that age. Cows usually need five consecutive calves by six years of age to generate enough income to pay their development and maintenance costs, so the age of six is was established as the target age for satiability. Without records of which females were retained for breeding and every calf they raised, cows with at least one calf before age six were considered to have opportunity, and successful cows had a calf at age 6 or older. Annual production records required by whole-herd reporting systems enable more rigorous definitions of stayability. Calving first as a two-year-old can indicate opportunity, and a calf every year through age six may be required for success.
Phenotype
Observations of stayability are binary, either success (1) or failure (0). An observation should be assigned to all females who are old enough and are considered to have had an opportunity to succeed. Missing values should be assigned to females who are too young or otherwise did not have an opportunity to succeed. That may include cows culled for reasons other than reproductive failure, breeding females sold before the target age, and females used as donors or recipients in embryo transfer and in vitro fertilization programs.
Adjusted Value
There is no adjustment to the binary (0,1) stayability observations.
Contempory Group
Contemporary groups for stayability should include all females entering the breeding herd with the same opportunity to stay. Basically, heifers
