Pushing The Weaning Envelope

June 24, 2011

7 Min Read
Pushing The Weaning Envelope

 It seems so simple. Just increase the weaning rate – the percentage of calves weaned per cow exposed – within a cowherd and production increases, thereby diluting costs.

From an industry standpoint, based on the Jan. 1 beef cow inventory of 30.864 million head, an increased weaning weight of every additional percent means the equivalent of 308,640 additional calves. Though possible, like so many other simple goals in the cow business, doing so is less than straightforward.

“I think we’re bumping up against the limit of what is economically practical,” says Clay Mathis, director of the King Ranch Institute for Ranch Management at Texas A&M University-Kingsville. “We have to be very careful we don’t throw a lot of money at something trying to pick up a marginal increase.”

According to data from Southwest Standardized Performance Analysis (SPA), Mathis says the weaning rate in the region is 82%-84%, year in and year out.

Likewise, Greg Lardy, a beef specialist and head of North Dakota State University’s Animal Science Department, says there’s always room for improvement. “But with any biological function, there’s a point of diminishing returns where the production maximum may not represent the economic optimum.”

According to data from the Cow Herd Appraisal Performance Software (CHAPS) program for 2006-2010, the average weaning rate for participants was 90.6%. “For the most part it’s stable,” Lardy says. “We see year-to-year variation based on our winters.”

Similarly the weaning rate in Nebraska ranges from the high 80s to low 90s, says Rick Funston, University of Nebraska beef reproductive physiology specialist. Though weaning rates remain confined to a narrow range, Funston says the trend toward less crossbreeding hasn’t helped. “Heterosis is extremely important to fertility in cattle,” he explains.

Although several factors influence weaning rate, including calf survivability and breeding systems, reproductive rate drives it.

Consider the most recent statistics from USDA’s National Animal Health Monitoring Service. Only 3.6% of calves born alive either died or were lost prior to weaning.

Environment drives limitations

In some parts of the world, the environment constrains the opportunity to an even greater degree.

Consider Montgomery County, TN, where John Bartee, University of Tennessee Extension beef cattle specialist, says the weaning rate is 78%, similar to the state average.

This part of the world is deficient in copper and selenium. That was compounded starting 15 years ago when coal-powered, steam-generation electric plants switched to coal with a high sulfur content. Smoke from those plants elevated sulfur content in the forage; sulfur ties up copper and selenium. Producers here are also utilizing more lower cost distillers grains and other grain co-products that are higher in sulfur content. Moreover, fescue is a primary forage source in the state, serving up accompanying challenges with fescue toxicosis.

Supplemental mineral programs are an obvious management strategy, but Bartee says there’s an economic limit to how much producers are willing or able to do.

In Florida, it’s not the environment as much as the evolution to using cows less suited to the environment, says Todd Thrift, University of Florida beef cattle management specialist.

This part of the world used to be ruled by crossbred Bos indicus (eared) cows that thrived amid the heat, humidity, dense parasite populations and the lush but poor quality forage. For various reasons, the state’s cowherd has become straighter bred with more Bos taurus influence.

“Can we increase the weaning rate here? Probably. Would it make us more money? Probably not,” Thrift says. “Our margins are about the same now that calves are worth $650 as they were when calves were worth $350.”

Mike Hall, Cal Poly State University senior beef cattle specialist, says California producers have also diluted heterosis with more straight breeding.

“A weaning rate of 85% here would be huge,” Hall says. “In the West, it often makes more sense to calve later, wean a lighter calf, and then market them as yearlings.”

Practical approaches

Bumping up against economic and environmental optimums across states and regions is one thing. Individual herds can make cost-effective improvements, though the practicality often depends on geography.

All those lending their expertise to this article emphasized managing maternal heterosis in the cowherd as one of the most universal and cost-effective ways to increase weaning rate, as well as gaining increased production performance and efficiency. All say, too, that any improvement strategy must begin with a foundation grounded in the basics – adequate nutrition, vaccinating against reproductive diseases, fertility testing bulls, effective overall health and parasite control programs.

Next, Lardy says, “You need to have a good enough handle on costs to know what incremental improvement is worth.” In other words, what is the cost and return of improving factors that influence weaning rate, such as cow conception rate and neonatal health care?

After that, Mathis suggests, “Look at which females are at the greatest risk of breeding late or not at all. We know it’s the heifers breeding back for their second calf, sometimes for their third calf, as well as the older cows. So the question becomes how to strategically provide the most vulnerable cows with supplemental nutrition in order to get them bred cost-effectively.”

“Pay attention to anything that improves reproduction, starting with the tried and true basics,” Thrift says. “For instance, sort cows based on body condition and target supplementation based on that. Manage heifers separately. Keep records so you know if a particular cow is always late calving and weans a calf below the herd average, rather than just eyeballing them.”

Incidentally, Thrift reminds that the target Body Condition Score (BCS) for mature cows entering calving is 5; 6 for heifers.

“I think there are optimums in all regions. Here, I believe it’s around 85%, maybe 87%, when prices are higher.” Beyond the aforementioned basics, he believes the practical, cost-effective way for producers in Florida to increase weaning rate is to shorten the calving season.

“Shorten the calving season from 120-180 days and get rid of the sub-fertile females. If you’re weaning rate is 82% today that would get you to 85% in three years,” Thrift says.

In California, though, Hall believes that strategy would leave too much potential revenue on the table.

“You can shorten the calving season, put pressure on them to calve in 60 days, but a bred cow is worth a lot more than an open one,” Hall says. “If a later calving cow won’t fit my operation, she’ll fit someone else’s.”

Understand that Foothills Abortion, anaplasmosis and trichmoniasis are ongoing challenges that make producers in California reluctant to impose any other constraints such as fewer breeding days.

Funston adds that, for folks in Nebraska, “now is not the time to shorten the calving season.” He explains that bred pairs from one of the university’s research herds were bringing $1,700-$2,000 this spring.

Rather, getting more cows bred earlier in the breeding season is the most practical, cost-effective way to increase weaning rate. Keeping other factors constant, such as genetics, dam age and nutrition, Funston says cows conceiving early in the breeding season also wean older, heavier calves.

Settle them earlier

Funston says the factors influencing how soon a cow cycles after calving include nutrition, body condition, ionophore feed additives, calf removal, estrus synchronization and bull presence:

  • Nutrition demands increase significantly in late gestation, even more in early lactation. Reproduction is a low priority when nutrient partitioning is considered. That’s why cows in thin body condition often don’t rebreed.

  • Body condition is potentially related to several reproductive events such as postpartum interval, services per conception, calving interval, milk production, weaning weight, calving difficulty and calf survival. Cows should be sorted by condition score and fed accordingly to maintain a moderate body condition of 5-6 on a scale of 1-9.

  • Cows and first-calf heifers fed ionophores (such as Rumensin and Bovatec) exhibit a shorter postpartum interval, provided adequate energy is supplied in the diet. Heifers fed an ionophore reach puberty at an earlier age and a lighter weight.

  • Calf removal, either temporary or permanent, can increase the number of cows that return to estrus during the breeding season. Response can be variable and management of this option can be difficult.

  • Estrus synchronization with progestins can bring cows into heat but will not solve fertility problems. These products may shorten the postpartum interval, provided all other management practices such as nutrition and body condition are optimum.

  • Bull presence post-calving has been shown to cause cows to cycle earlier.

No matter the strategy considered, Lardy emphasizes, “The challenge is trying to understand what you can do from the standpoint of economic optimums rather than biological maximums.”

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