Agriculture News: Hay not enough to keep cattle healthy in winter

By Keenan Bishop, Published:

Every fall I get up on my soap box and talk about how you should test your hay so you know exactly what you have, or more importantly, don’t have. It looks like this was the winter that it really paid off to do so.

Some farmers will feed only hay to their cattle, forcing them to use up fat reserves over the winter in order to meet their needs. They can usually get away with this during our relative mild winters even though the cow may lose a body condition score or two. But this makes it harder for them to gain it back in time to rebreed in the spring.

Dr. Michelle Arnold, ruminant extension veterinarian and Dr. Louis L. ‘Lucky’ Pittman Jr., veterinary pathologist/section head (Breathitt Veterinary Center) have an article in this months’ “Off the Hoof” (which is put out by UK’s beef specialists) titled “Recent Winter Weather Conditions Impact Kentucky Cow/Calf Herds and Producers.”

They are reporting high numbers of adult cattle that have died, basically of starvation, with their bellies full of hay. Even with plenty of free choice hay, they succumbed to malnutrition.

They point out that the lower critical temperature for cows with dry, heavy winter coat is 18 degrees. If cows are wet, the lower critical temperature is surprisingly high, at 59 degrees. For every degree that the environmental temperature drops below the low critical temperature, a cow must expend 2 percent more calories in order to maintain body heat and condition.

Hay not enough

During extended periods of cold, if producers are not supplementing cattle with adequate energy and protein sources, hay alone may not provide sufficient nutrition to meet the animals’ needs.  This will result in depletion of body fat stores, breakdown of muscle protein and death due to insufficient nutrition.  

They go on to explain that in the last 60 days of gestation, an adult cow (1,200 pounds eating 2 percent of her body weight) requires at least 54-56 percent TDN and 8-9 percent available crude protein while an adult beef cow in the first 60 days of gestation requires 59-60 percent TDN and 9-10.5 percent available crude protein. I’ve seen many hay tests from here come back below 9 and even 8 percent crude protein.

They’ve also received numerous calls and diagnostic submissions associated with “weak calf syndrome” or full-term calves which were presumed to have been born dead. Almost without exception, these calves were born alive, but never stood or nursed, and there were no infectious cause of mortality.

Calves born to protein-deficient dams are less able to generate body heat and are slower to stand and nurse compared to calves whose dams had received adequate dietary protein during the last 100 days of pregnancy.

Risk of death

Calves born during unseasonably cold weather, with ice or snow on the ground, are at risk of chilling and death if they do not stand and nurse soon after birth. Inadequate energy and protein nutrition in the dam often leads to higher calf mortality in these conditions.  Additionally, colostrum quality and quantity from protein and energy deficient dams may be less than optimal for best calf survival and performance.

The article goes on to say that some producers in Kentucky have not provided adequate mineral supplementation to their cattle this winter, as copper and selenium levels in liver samples analyzed from a number of animals have been far below acceptable levels. We’ve had several cases of this here in the county.

Many of these cases have died of malnutrition and/or herd-wide outbreaks of respiratory disease (including pneumonia in pre-weaned calves). They are also seeing cases of grass tetany cases in early lactation cattle consuming only hay, which suggests that 2013 hay may be low in magnesium content.

To read the whole article or the newsletter call the Franklin County Extension Office and ask for a copy at 502-695-9035 or email me at kbishop@uky.edu.

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