Herd health: UW specialist discusses ways to maintain herd performance during drought

University of Wyoming (UW) Department of Animal Science Assistant Professor and Extension Beef Specialist Dr. Shelby Rosasco presented during the Progressive Rancher Forum on Dec. 9 at the annual Wyoming Stock Growers Association Winter Roundup Convention and Trade Show held at the Ramkota Hotel and Conference Center in Casper.

Rosasco earned her PhD in animal science from UW, where her research emphasized cattle nutrition and reproduction.

She has worked closely with producers across the state to deliver practical solutions and information for improving beef production. 

During her forum presentation, she discussed the impact of drought and provided information on how to help Wyoming beef producers improve herd management practices and profitability. 

Priority

“We need to think about animals’ requirements throughout the year,” Rosasco stated. “And in a drought situation, we have to think about additional forage intake to meet those requirements, especially if we have lactating cows.”

She mentioned providing high-quality supplemental feed to compensate for the reduced nutritional value of pasture is important to meet the needs of a lactating cow during a drought, but testing forage quality will help make a more informed decision.

“Testing forage quality is important because knowing forage quality will help the producer know what sort of supplementation they will need to add during different points of time,” Rosasco added. 

Estimates of protein, mineral and vitamin content can be made relatively easily through forage testing, but it should be done regularly.

“If an analysis was done last year or two years ago when it was a good year, the results will not be accurate now, and new testing should be done,” she mentioned. “Testing costs a little bit of money, but it will help make better strategic decisions for the future.”

Grouping cows together to improve nutritional efficiency allows each group to be fed a more precisely-tailored diet, minimizing waste and maximizing the utilization of nutrients for optimal milk production and overall herd health.

She continued, “Based on cows’ age and gestation, it’s best to match feed resources with the animals’ requirements to avoid nutritional gaps.”

Splitting cows into groups with tailored feed rations allows for precise nutrient utilization and reduces feed costs while maintaining or even increasing performance.

Protein

“Another thing to think about as we talk about supplementation during a drought is energy – it’s going to be the most limiting nutrient to worry about,” Rosasco said. “Especially in the winter, we need to think about protein requirements.”

Energy and protein limit a cow’s performance, so supplementation should be evaluated when added to a nutrition program.

She added, “The protein level will drive a cow’s forage intake, but during a drought situation where forage is limited, producers will need to add supplements closer to 15 to 20 percent protein to not drive her intake even farther and utilize more forage which is already limited.”

When forage supply is critically low in a drought, meeting the cows’ energy requirements using the most economical feed available is a priority.

Body condition scores

Body condition score (BCS) indicates a cow’s body composition or relative fatness.

“Obviously, we are not all going out and weighing each cow every day, so the easiest way to assess the condition of the animals is to record a herd average,” Rosasco said. “If the BCS decreased from a five to a four, then we know we are not meeting the herd’s nutritional requirement. If the BCS went from a five to seven, we are overfeeding.”

Rosasco noted UW has a three-step BCS guide, which is very useful and easy to use.

“We usually want to see cows somewhere around a BCS five, but what does it take to ensure they stay there during a drought situation and stay productive?” she asked.

In recent research, a cow’s BCS score around calving correlates to the conception and pregnancy rate.

Rosasco stated, “So we know if she is in good condition at calving, we’re going to generally have a good pregnancy rate.”

If a cow has a low BCS at calving, it is extremely hard to get her to gain weight while lactating with a calf by her side.

“There will always be some fluctuation in BCS, so it’s a good idea to keep an eye on BCS as cattle move through the year, as these scores correlate with summer and fall nutrition and stage of gestation,” she added.

Reducing nutritional requirements

“If we think about reducing nutritional requirements, one of the biggest ways is obviously culling, but the second way is early weaning,” Rosasco stated. “There are certainly some pros and cons to early weaning.”

One of the advantages of early weaning is it can improve a cows’ BCS. Recent research prove early weaning reduces a cow’s nutrient demands, as she is no longer lactating and can put some weight on.

She added, “The challenge is what is considered early weaning – 30 days, 60 days or when the calves are six weeks old.”

According to some literature, if the calf is weaned at six months of age – 30 days early – the cow’s daily energy requirement declines by 18 percent.

Other research shows weaning calves as early as 45 days of age has been used by producers to encourage cows to cycle and rebreed while giving them time to increase their BCS.

However, weaning calves at this age may be a viable alternative if forage is scarce in the latter part of the grazing season. 

In this situation, cows usually have better body condition because nutrients are not needed for lactation. 

“It is estimated for every two and half days the calf is removed from the cow, there is an extra one day of forage available for grazing,” she stated. “So, for every 100 calves weaned 60 days early, a producer will save enough forage to maintain six to seven additional cows for one year.”

She reminded the group early weaning is not a fix-all solution, but it can allow cows on the cull list to be removed earlier.

Immunity

“We need to protect our calves and think about their immunity during a drought,” Rosasco said. “The first thing we think about when building their immune system is colostrum.”

The first line of defense for a calf is to make sure it receives colostrum. However, depending on the situation, it could be challenging.

“Colostrum builds the calf’s immune system, and the longer the calf waits for colostrum, its immune system will start to decrease,” she mentioned. “In this case, the producer will need to make sure the calf’s system continues to develop, and vaccination is a great tool to have in the toolbox.”

Managing a drought situation requires implementing multiple practices to reduce stress and improve immunity during and after gestation for both the cow and calf.

Melissa Anderson is the editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.