A large portion of the U.S. has been in a drought for a number of years and the effects on an affected cowherd can be far-reaching. Cows that enter the winter in poor body condition not only have lower survivability themselves, but they also have a greater chance to:
Have a weak or stillborn calf.
Produce an inadequate quality and quantity of colostrum for their calves.
Have a calf with a reduced weaning weight.
Fail to rebreed the next breeding season.
Numerous studies point to precalving nutrition as the key to calf survivability and reproductive success. The 60 days before calving begins is surely no time to “starve the profit” out of your cows.
To prevent potential problems, herds with limited winter feed resources should:
Wean calves earlier than seven months of age.
Explore the purchase of by-product feeds to feed to calves during their 30- to 45-day preconditioning period (then sell calves or retain ownership into a feedlot).
Pregnancy check and sell open and late-calving cows.
Sell any problem cows (see “Does she stay or does she go?” September BEEF, page 10).
Sell low-indexing cows.
Look into selling all your bred heifers to another producer as they need additional nutrition compared to adult cows.
Contact your state's beef cattle association to see if they know of producers in other parts of the U.S. that would be interested in wintering cows on shares.
Analyze the cost-effectiveness of purchasing by-product feeds for winter feeding.
Look At By-Product Feeds
If by-product feeds are available at a reasonable cost, visit with your veterinarian, nutritionist or Extension specialist to assist you in formulating cost-effective rations. Just because it's tradition to feed hay to cows in the winter doesn't mean there aren't more cost-effective alternatives. I recently visited a herd in which the cost was 60¢/cow/day for a winter ration made primarily of by-products.
Condition Score Is So Important
Adult cows need to calve in a body condition score (BCS) of 5.5-6.0. Adding weight earlier in the winter is much more efficient than a month or two prior to calving.
If cows haven't been dewormed and treated for lice, now is the ideal time to do so. We would like to have a cow go into the winter without the extra burden of feeding internal and external parasites.
Bred heifers need to be in even better condition than adult cows. Average milking heifers should calve at a BCS 6.0-6.5, but if the heifer has the genetics to be a superior producer, she should calve in a BCS 6.5-7.0. Heifers are still growing and need the added condition to “bounce back” more quickly after calving so they can be rebred on time.
|BCS 4||BCS 5||BCS 6|
|Body weight at calving||744||825||933|
|Calf birth weight||64||67||71|
|Percent bred back by days in rebreeding season|
|BCS = body condition score|
|References: Spitzer, JC, Morrison, DG, Wettemann, RP, Faulkner, LC. Reproductive Responses and Calf Birth Weight and Weaning Weight as Affected by Body Condition Score at Parturition and Postpartum Weight Gain in Primiparous Beef Cows. J. Animal Science. 1995. 73:1251-1257.|
Many producers worry about increased dystocia rates when we suggest that heifers calve in a BCS 6.5-7.0. But numerous studies show that while birth weight may increase 0 to 7 lbs. if a heifer improves in BCS from 4.0 to 7.0, the rate of calving difficulty does not increase. (See Table 1.)
In fact, extremely thin heifers — a BCS of less than 4.0 — can have an increased rate of dystocia because they are so thin. They just don't have the muscle and stamina to expel the calf.
Having heifers calve in a BCS of less than 5 to decrease dystocia rate is one of the most widespread fallacies in the beef industry. Too many times, we see a group of heifers that calve too thin and then fail to conceive the following breeding season.
We simply can't afford to have these “one-hit wonders” in our herds. Calve heifers in great shape and watch them cycle right on time for the following year. As you can see in the study by Spitzer et. al., in Table 1, having heifers in a BCS 6 did not increase dystocia score and did have a tremendous positive effect on subsequent fertility.
Drought conditions can be trying times for cattle producers. But with limited feed, you need to put what you do have to the best possible use on the farm or ranch. Be sure the cows you are feeding are the most productive ones you have.
Mike Apley, DVM, PhD, is an associate professor of beef production medicine at Iowa State University in Ames. W. Mark Hilton, DVM, is a clinical assistant professor of beef production medicine at Purdue University in West Lafayette, IN.