In contemplating a change in calving season, the health considerations for young, newborn calves are paramount. After all, weather is the principle factor affecting calf health.
If you're constantly fighting muddy, cold conditions due to snow or rainy weather, then you may want to opt to calve in the late spring, summer or fall. The risk of wet, muddy conditions is typically less during these times than in early spring. Consider these points:
Calves born in a dry, clean environment are less likely to scour and have respiratory problems. One report found calf death loss at or shortly after birth to be 1.2% for fall calves versus 5.6% for early spring calves.
Fall-calving cows have fewer calving difficulties than early spring-calving cows; calves born unassisted are more vigorous at birth and stand to nurse more quickly.
In nearly every study to determine the most common causes of neonatal calf death, the majority were caused by dystocia and poor weather at or near calving. In Plains states, a late spring snowstorm can spell disaster for the calf crop. In the southern Midwest and northern part of the Southeast, the worst-case scenario is a heavy, wet March snow on top of existing muddy conditions that chills calves and kills them due to exposure or inability to nurse.
There are two peaks for morbidity in calves. The first comes in the first weeks of life; the second is in the first 30 days after weaning.
While it may appear that the calving season would have little effect on bovine respiratory disease (BRD) at 6-8 months of age, studies show calves weaned at a time of wide temperature fluctuations experience greater sickness in the feedlot. One of fall calving's real health benefits is that calves are weaned in late March through April versus October-November weaning for spring-born calves.
A better alternative for early spring calves is to wean in mid-August to September when weather is less volatile.
Also, fall-born calves have more likely been exposed to creep feed, thus easing their nutritional transition at weaning.
No matter the calving season, there are three reasons to separate heifers from cows during the period 60 days pre-calving until the start of rebreeding:
Heifers need more feed. Not having to compete with older animals allows them to get their fair share.
Heifers tend to have more calving problems. Heifers in a small group are easier to examine and take less labor.
Calves born to heifers are more susceptible to disease than calves from older cows. Keeping cows and heifers separate until their calves are 30-90 days of age will pay huge dividends.
Calving heifers 21 days ahead of the cows is often recommended. This is a positive suggestion in regard to future conception rate, but it can negatively impact calf health.
A herd calving from March 1 to April 30 would have the earliest calving heifers dropping calves the first week of February. If that thought makes you cringe, the plan may not work for you. Obviously, if you have only a few heifers and have adequate shelter in case of heavy snow, extreme cold or an abundance of mud, this plan could still work for you.
Still, the aforementioned weather concerns may be a reason to stop fighting Mother Nature and switch to a more reasonable calving season. Beef cattle are supposed to be low labor, low input (but high profit) livestock that work hard for you.
Herd Health Programs
Vaccination programs for cows and calves are similar for fall and spring calving herds. General vaccination recommendations for cows and bulls include leptospirosis, infectious bovine rhinotraecheitis (IBR) and bovine viral diarrhea (BVD).
Meanwhile, calves should be vaccinated for the clostridials, IBR, BVD, parainfluenza3 (PI3) and bovine respiratory syncitial virus (BRSV).
For vaccination recommendations specific to your location, work with your local herd-health veterinarian to tailor a vaccination program to your operation.
Other health management procedures that should be performed include preg-checking the cows and breeding soundness exams (BSE) on the bulls.
Preg-checking time shifts with the breeding season. A benefit to fall calving is that open cows can be sold immediately, at a time when the cull-cow market is typically at its peak.
Have your herd-health veterinarian perform a complete BSE on each bull before each breeding season, even if a bull passed his BSE in the spring.
The physical exam should include eyes and feet, scrotal measurement, testicular palpation, accessory sex gland assessment, and motility and morphology of the semen sample. Observe all bulls passing the BSE to be sure they actually breed cows.
In some cases, bull numbers can be reduced if you have both a fall and spring calving herd, allowing you to more efficiently utilize your bull battery.
Parasite control is important. Generally, deworm after a hard freeze in the fall so that cows are over-wintered free of parasites. They can also be dewormed in the spring, six weeks after pasture turnout.
After deworming, a cow will be clean but will become parasitized again when she grazes an infected pasture. Be sure to use a Type II dewormer, which eliminates all adults and developing stages within the cow. Check with your local herd-health veterinarian on products and to develop a program specific to your environment and operation.
Jerry Rusch, DVM, is a beef cattle practitioner with Spring Mill Veterinary Service in Mitchell, IN. W. Mark Hilton, DVM, is a clinical assistant professor of beef production medicine at Purdue University in West Lafayette, IN.