Planning through breeding
The dams you breed today will influence the herd you own in the future. Daryl Nydam, DVM, Ph.D., and Julie Adamchick, DVM, Ph.D., presented “Breeding Today for the Herd You Want Tomorrow: Tools to Support Semen Choice Tradeoffs” as a webinar in Cornell’s College of Veterinary Medicine’s “Boots in the Barn” series.
Knowing which cow to replace and which cow to keep can dramatically affect herd dynamics. Nydam presented a hypothetical situation of Cow #1492.
“We want to know if she should stay or be replaced with an average springing heifer,” Nydam said. “She has four good legs, two good eyes, eats and makes her appointments to be milked. She is not a welfare or behavioral concern.”
On her third lactation, she is 120 days in milk. But #1492 has one blind quarter from a previous bout of mastitis. Occasionally, she has high BHB and sometimes a floating DA. She began two of her lactations with metritis.
“Every day, we want to know if she should keep her place or be replaced,” Nydam said. “She’s been bred, but we don’t know if she’s pregnant. Yesterday she made 120 lbs. of milk and yesterday she did. What if she’s making 50 lbs. yesterday, today and likely tomorrow? Does she stay or go?”
Many operators would allow her to stay if they had a ready replacement and would remove her from the herd if they didn’t.
“Involuntary culls are due to things like lightning strikes, cattle rustling and maybe she kicks you every day,” Nydam said. “Marketing a cow is an economic decision. Sell her when her net present value is less than that of an available average replacement heifer. She’s got to go. Sometimes, [it’s] a conscious decision to ignore economics – for example, she was your child’s 4-H cow or the cutest cow on the farm.”
Producers must look at “cow longevity” – the productive life of an individual animal from first calving until leaving the herd, along with herd longevity (the average productive life of the animals within the herd). The replacement rate is the inverse of productive life. It is the percent of the adult herd that is replaced by an income animal each year, similar to a cull rate or turnover rate.
“We try to make that example with Cow #1492 – includes ‘risky behavior’ and milk productivity and calving productivity,” Nydam said.
Herd longevity is also driven by herd level breeding and youngstock rearing decisions. Nydam views the average herd longevity as a “push” and not a “pull” decision. A “pull” is a cow that gets mastitis for the second time, prompting a replacement. A “push” is a heifer calving, allowing the farmer to market a cow getting mastitis for the second time. Of course, the healthiest, most productive cows are the animals any operator wants since there are a finite number of spots in any given herd.
“Having an older herd is not undeniable proof of the ‘healthiest, most productive cows,’” Nyman said. “Remember, the average herd ‘age’ is a push situation, not a pull. We are not proponents of ‘breaking cows,’ nor are we proponents of keeping cows around longer than we should. If management doesn’t improve, and we keep cows longer, we will probably see less milk per cow and an increase of disease.”
Nydam compared two herds: #2066 and #3388. Herd #2066 has a replacement rate of 20%. The average daily milk production is 66 lbs. Over 15 years, the farm has sold two mature market cows, replaced those cows (incurring replacement costs) and sold 13 crossbred calves.
In Herd #3388, the replacement rate was higher at 33%. Average daily milk production was 88 lbs. The farm sold twice as many mature market cows (four) and made the same number of replacements. The farm also sold 11 crossbred calves.
After 15 years, the farms’ profitability differed. The average annual marginal cash flow for Herd #3388 was 26% greater. Herd #3388 also had lower enteric methane intensity.
“Turning the herd over with a higher milk production is a little better environmentally,” Nyman said. “Heifers are less costly, environmentally and economically, than good lactating cows.”
The breakeven analysis revealed that Herd #2066 must make 84 lbs. of milk to meet the marginal cashflow of Herd #3388 and it must make 74 lbs. of milk to break even with the enteric methane intensity.
“We should focus less on replacement rate and more on the decisions and factors that lead to that replacement rate,” Nydam said.
Looking at disease rates and how to lower them; improving cow comfort; and breeding for the number of heifers the farm anticipates needing are strategies that can affect replacement rate.
The number of replacement heifers a farm has can be the limiting factor to keeping those spots filled with the healthiest and most productive cows. It’s determined by the number of dairy females born two years earlier and conceived nine months before that. The farm’s replacement heifers come at the cost of not producing and selling beef-on-dairy calves.
“The decisions we make today are a three-year decision in what our herd will look like,” Nydam said.
Adamchick encouraged farmers to check out SemenSolver v. 2.0 available at hdl.handle.net/1813/117694. Developed by Cornell, the free spreadsheet can help farmers plan their breeding program.
By using SemenSolver logic, “you know how many replacement heifers you want in a given year, three years down the road,” Adamchick said.
This assumes that a farmer is breeding animals to sexed semen to cover replacement needs and wants crossbred beef calves for all the rest.
“There’s another option if you want to stratify these inputs by lactation among cows,” Adamchick said. “It gives you the resulting semen mix as percent. It breaks it down into the number of breedings to sexed semen that you’d need to use per week and month passed on the parameters you put in.”
She added that the spreadsheet can be adjusted to farm-specific inputs and assumes steady state (a herd that’s not growing) and that the farmer wants next year to look like this year. But SemenSolver does not recommend the best replacement rate.
Growing the herd isn’t only about the cost of replacements. Adamchick said that as farmers consider scaling their herds, they should also take into account additional investments such as labor, animal housing and equipment, and compare at what point the production of the additional animals will result in profitability.
“What is the amount of milk they would need to produce to offset their additional cost?” she asked. “One way to think of this is the average increase per head, per day of production. Or thinking of the replacements and how much additional milk she’d have to replace above what the cow she replaced would have made.”
Adamchick said farmers can also raise heifers and, if needed, sell them as springers instead of introducing them to the herd as a sort of “insurance policy.”
“There’s clearly no one-size-fits-all answer,” she added. “It’s influenced by milk production spread; reproductive performance; youngstock costs, losses and capacity; other farm bottlenecks; and risk and cash flow preferences. Use the data, do the math and you don’t have to guess.”
