January 13, 2023 at 8:48 p.m.
Earlier calving does not equal more profit
Milk production ultimately suffers, and it goes deeper than the first lactation alone. Staley has studied production data from 500,000 cows and has discovered a formula that proves the importance of mature heifers.
“I call it the Peter Pan problem, alluding of course to the children’s comic character,” Staley said. “The individual that never grows up.”
Staley is a technical services specialist with Diamond V and a veterinarian who spoke in a Professional Dairy Producers podcast Dec. 28, 2022.
Heifer maturity means the phenotypic characteristics – frame and body weight – that allow full expression of genetic potential over the animal’s lifetime. For a long time, the standard has suggested heifers need to be 85% of the mature body weight post-calving, and close-up heifers should be about 95% of mature body weight.
If an animal does not reach the required level of maturity before calving, she will reach it during lactation at the expense of production, Staley said. She will inevitably reach the benchmark on the lactating ration, ultimately increasing the growing cost.
“It nets out to an 8:1 ratio,” Staley said. “For every 1 pound that she has to mature after calving, it will cost 8 pounds of milk.”
Staley said it also takes longer because the daily growth rate drops significantly after calving. Sometimes it can take up to 500 days, which could be a lactation. Some heifers simply never catch up.
Staley has determined that week 10 of the first lactation approximates the herd annual average milk.
“If you want a 100-pound herd, you’ve got to have a 10-week lactation one that is 100 pounds,” Staley said. “Ninety-two percent of the average annual herd milk variation can be explained in lactation one.”
This predicts the average annual milk for the entire herd from a single value. It also works in reverse, with the first lactation setting the ceiling for the whole herd.
“The herd cannot outperform the production level set by lactation one,” Staley said. “You can’t cull your way there, you can’t repro your way there, and you can’t feed your way there. It’s basically the ace card.”
Staley and colleagues have determined that the age at freshening impacts the second and third lactations also.
“This is unfortunately the gift that keeps on giving,” Staley said. “It leaves an awfully long shadow.”
In order to evaluate a herd and be able to shift the focus to mature heifers, Staley said the third- and fourth-lactation groups of cows need to be weighed in order to determine the herd’s mature body weight. Then, springing heifers and fresh cows need to be weighed. After that, the weight difference between desired and actual weights can be calculated. This way, it is clear what the system is delivering, Staley said. From there, the average daily gain can be calculated to see what the heifer raising system is achieving.
The average daily gain or the age at freshening are the two variables to consider when deciding what to change, Staley said. And, if the average gain cannot be increased, breeding must be delayed until the animal reaches that mature point.
Staley said dairy farmers should set health and growth goals for all key stages of growth from birth to calving. The goal can be to calve heifers as early as possible, but they must be mature at calving.
Staley said there has been a trend over the past 20 years encouraging producers to calve their heifers in at a younger age. The thought was the animal would begin milk production earlier, reduce heifer inventory and lower heifer feed costs. The message that got missed, however, is to manage the heifers to be mature at a younger age.
Staley said calving immature heifers has not been successful because the growth management was not changed.
“I’m not saying you should not breed heifers earlier, but you should get them to maturity earlier,” Staley said. “You can have your cake and eat it too.”
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