AS-405 • Rev. 1975
animal sciences beef
W. L. Singleton and L. A. Nelson, Animal Sciences Department
In the U.S., 6 to 10 percent of all calves born in beef cow herds die at or soon after birth. Approximately half of those deaths are due to calving difficulty (dystocia). This multi-million dollar annual loss is three times that resulting from abortions and second only to losses from cows failing to conceive.
Calving difficulty has received much attention in recent years, largely because of the mating of larger European breeds of bulls to British breeds of cows. Increased calving problems are also being encountered within purebred breeds, because genetically large bulls are often mated to cows of only average size.
The purpose of this publication is to acquaint cattle producers with calving management principles that will help minimize calf loss in their herds. Discussed are: causes of calving difficulty, stages in the birth process, the problems that can crop up in each stage and howto handle them, and an outline of basic steps in calving assistance.
FACTORS CAUSING CALVING DIFFICULTY
About 80 percent of all calves lost at birth are anatomically normal. Most of them die because of injuries or suffocation resulting from difficult or delayed
A profitable cow herd begins with a live call from every cow.
parturition (calving). Factors contributing to calving problems fall into these three main categories—calf effects, dam effects and fetal position.
Calf Effects
Heavy birth weights account for most of the problems related to the calf. Birth weights are influenced by: breed of the sire, bull within a breed, sex of the calf, age of the dam and, to a slight degree, nutrition of the dam.
Dam Effects
Several factors associated with the cow influence dystocia, the major ones being her age and pelvic size.
Age. Two-year-old heifers require more assistance in calving than do cows, because they are usually structurally smaller.
Pelvic area. Pelvic area (birth canal) increases as the female develops to sexual maturity. Thus, a higher proportion of calving difficulty in 2- or 3-year-old dams is due to smaller pelvic openings. Heifers and mature cows with small pelvic areas are likely to require assistance at calving. However, even heifers with large pelvic areas may need help.
The calf’s birth weight and cow's pelvic area have a combined effect on dystocia. Many heifers giving birth to calves weighing over 80 pounds will have difficulty, even if they have large pelvic areas. Two-year-old heifers tend to have either a pelvis too small ora calf too large to allow them to deliver without assistance. Therefore, calving problems could be reduced by decreasing birth weight through bull selection or increasing pelvic area by selecting the larger, more growthy heifers.
Fetal Position at Birth
About 5 percent of calves are in abnormal positions at birth, such as foreleg or head turned back, breech or rear end position, sidewise or rotated, etc. (Figure 1). It requires the assistance of a veterinarian or experienced herdsman to position the fetus correctly prior to delivery.
If fetal position cannot be corrected, the veterinarian may have to perform a caesarean section.
Assisting the Beef cow at Calving Time