Factors affecting calving difficulty
Cattle producers take great care in their herds and want to achieve a high percentage of live births during calving season. Every live birth that ends with a marketable feeder calf can help during these difficult times. Today’s article will center on factors that affect potential calving difficulty during calving season. I will be sharing information from an original UGA publication by former UGA Extension Animal Scientists, Tim Wilson and Johnny Rossi.
The technical term for calving difficulty in cattle is dystocia. In simple terms, cattle producers want a cow or first-time calving heifer to have a live birth unassisted. When you have calving difficulty issues with a cow, it can lead to chain reaction of negative impact for the reproductive efficiency of that animal. The worst case scenario is the death of not only the calf, but in some cases the mother. A problem calving situation can lead to a calf that even though born alive will be an animal that just will not perform well.
A dystocia situation can also lead to a cow that will be delayed in conceiving in breeding season. Most cattle operations have a controlled breeding season that will lead to a controlled calving season. Cattle that cycle later will calve later than the other cows thus affecting the uniformity of a calf crop. The best option for a cattle producer is to try to keep calving difficulty to a minimum on their farms. I will add that with our drought and limited feed supplies, this can be a tough year to get cattle breed back in the first place.
One factor to consider in calving difficulty is sire selection. Years ago, there were some breeds that were blamed for being associated with more calving problems. In our time, there are sires within all breeds that can cause calving difficulty when bred to certain females. This makes taking the time to match sires to the correct females important. Most cattle producers are quite aware of the importance of breeding heifers to known low birth weight bulls for that first calving season. When those heifers mature into older cows, they should be able to deliver larger, heavier calves. One management tool is the use of EPDs or Expected Progeny Differences in matching sires to their cows.
Note that EPDs have accuracy values that can be used in evaluating the accuracy of a certain EPD. Older bulls where progeny data has been returned to breed associations should have a higher EPD accuracy than a young bull that is on the market when using artificial insemination. Take EPDs into consideration also when you are purchasing bulls private treaty or at live auctions. I will add that a lot of time is put in to select low birth weight calving sires when we are artificially breeding heifers in our UGA HERD program annually.
Another factor to consider is temperature in calving difficulty. Note that environmental factors are responsible for almost 55 percent of the calving difficulty according to our publication. Birth weights have been known to vary greatly from year to year even when the same genetics and farm management is the same. I will add that several studies have shown that calves born in the fall will weigh less than calves born in winter and spring. This can be attributed to increased feed supplementation to the mother in cold winter months which can result in larger calf size.
I know this may sound off to the previous paragraph, but one study showed that high feeding levels pre-calving did not show a significant impact on birth weight or dystocia as compared to lower feeding rates. Do note that lower feeding levels can result in lower cow weight gain, less milk production in lactation, more situations of scours in the calves and a reduced pregnancy rate in breeding season. Finally, abnormal deliveries at birth are also a big factor in calving difficulty. For more information, contact UGA Extension- Gordon County at 706-629-8685 or email gbowman@uga.edu.