More than two-thirds of calf deaths occur within the first 96 hours of life.
At least two-thirds of these mortalities can be attributable to calving difficulties or dystocia.
Calves that are born to a cow or heifer suffering from calving difficulties are about 2.5 times more likely to get sick in the first 45 days. A sobering statistic reveals that calves that experience dystocia are 13 times more likely to die within 12 hours of birth.
Most producers have successfully reduced the number of heifers and cows that suffer from calving difficulties, mainly by selecting for easy calving bulls with low birth weights. Birth weights have a dramatic impact on calving difficulty and account for 30 to 50 percent of the variability in dystocia rates.
Producers have also improved their heifer replacement rearing programs and have made sure heifers are of adequate size to limit dystocia problems.
However, despite lowering the incidence of dystocia, we will always have heifers and cows that occasionally require assistance at calving.
Breech births, backward calving, twins and calves with a leg back or other abnormal presentations are beyond the control of the producer. Recognizing these cases at an early stage can mean the difference between a live calf and a dead calf.
It would be ideal if more of our cows would give birth during daylight hours. Calving difficulties are easier to detect in the light of day, and more help is often available if a cow needs assistance.
It would also definitely improve our own sleep patterns.
However, can we influence this?
Studies have looked at the timing of calving and whether we can influence this by modifying feeding time.
Researchers at Kansas State University, South Dakota State University and Oregon State University attempted to look at some of the factors that affected the timing of calving in beef cows. The study was published in the Professional Animal Scientist Journal in 2008.
The researchers had records from the University of Idaho beef research herd, which recorded calving times of individual cows for more than 15 years. In this herd, cows were fed forage based rations daily between 6 and 8 a.m. beginning two months before calving.
The other experiment followed beef cows at the Kansas State beef herd, where timing of births were similarly recorded. In this herd, the forage based ration was fed daily between 4 and 6 p.m. beginning two weeks before calving season.
A greater proportion of cows gave birth during daylight hours in the herd that fed in the late afternoon or evening. In this herd, 85 percent of the cows gave birth between 6 a.m. and 6 p.m.
Only 52 percent of the cows in the herd that was fed in the morning calved between 6 a.m. and 6 p.m.
This finding has been shown in a number of other studies. For example, a study in 1981 showed similar results with 79 percent of cows calving during the day if fed in the evening compared to 57 percent of cows calving in the day if fed in the morning.
It would appear that the timing of feeding does affect the timing of calving.
The other interesting finding was that cows tend to give birth at about the same time of day from year to year.
Researchers analyzing the 15 years of data could show that regardless of when feed is provided, the time of day a cow will give birth could be predicted within 4.25 hours of the previous calving time.
If cows were fed in the evening, the variability of calving time became even less and could be predicted within three hours of the previous year’s calving time.
As well, it appeared that heifers tended to follow the same pattern of calving as their dams.
However, I am sure there are exceptions to these broad generalizations, and you should not count on predicting the time of day or night that a particular cow will calve from year to year.
John Campbell is head of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.