productivity, profitabiltiy, longevity, cows
Making sure profitable cows continue to be profitable beyond their second lactation should have a positive economic impact on the net returns of a dairy farm. The rationale behind this statement is that rearing, fixed, and variable costs are spread over three or more lactations. Longevity has been defined as the ability for a cow to delay involuntary culling or to survive to 48 months of age. Productive life could thus be defined as the number of lactations a cow completes, or is expected to complete (death is usually unexpected!), prior to culling. The economic advantage of retaining a profitable cow as long as possible will obviously be influenced by the feed/milk price ratio during her productive life. Increased longevity will have a positive economic impact when feed to milk price ratio is low. If she maintains a reasonable milk yield, it also makes more economic sense not to cull a cow when beef prices are low. Increased longevity will also allow the farmer to focus on voluntary culling for low productivity and to reduce the number of replacements needed every year.
Garcia, Alvaro, "Cow Longevity" (2001). SDSU Extension Extra Archives. 118.