Dairy heifer growth curves traditionally have been based on breed standards. Unfortunately, those standards do not accommodate for genetic variation and goals in individual herds, nor do they apply to crossbred animals.
That"s why dairy consultant Jim Barmore was excited to find a new spreadsheet from Penn State University that customizes heifer growth charts to specific herd goals. Barmore, with GPS Dairy Consulting, Verona, Wis., says the new tool can help his clients adapt nutritional strategies to achieve growth goals tailored to their own herds.
"Herds have become very specialized in their approach to retaining and growing the best-quality replacement heifers," says Barmore. "This tool allows us to plug in a herd"s desired age at first calving and mature size of animals in the herd, and then generates a curve that shows the target size according to age from birth to calving. It is much more valuable than measuring growth at first calving, which is too late to make a difference for those animals."
Developed by Jud Heinrichs and his colleagues at Penn State, the spreadsheet assumes a target body weight of 55 percent of mature weight at first conception and 85 percent of mature weight after first calving. The height target is 55 percent of mature height at birth, and 96 percent of mature height at calving. Either wither height or hip height can be used to assess height, as long as the same measurement is used for heifers and mature cows. Mature size of cows can be entered as a herd average, or individually for each heifer"s dam.
The spreadsheet can be accessed here.
A metric version also is available.