Dystocia is expected to occur in ~10–15% of first-calf heifers and in 3–5% of mature cattle. Although dystocia cannot be eliminated from a herd, the incidence can be greatly reduced by management decisions made before the breeding season and during gestation.
Heifers and cows should be gaining weight before calving, but overconditioning causes excess fat deposition in the udder and results in lower milk production. Excessive fat deposition in the pelvis also may result in dystocia. Good body condition aids in calving and also milk production. If cows are placed on a ration to maintain or increase body weight after calving, breeding will be more uniform and the breeding season shorter.
Calving facilities may be needed in certain areas. They should be in good repair and functional before the calving season starts. Weather conditions, geographic differences, and local experience usually dictate how much attention and individual care calves will need immediately after birth. The calving environment (eg, calving sheds, small pastures) must be clean, dry, and protected from the weather. A clean area to handle dystocia problems is also needed. Calving in a clean area, separated from the rest of the herd, helps to reduce calfhood diseases, particularly scours. In large herds, several small calving pastures allow regular rotation to avoid buildup of disease-causing organisms. When calving stalls are used during inclement weather, they should be cleaned and disinfected between calvings.
Close observation of labor is necessary to determine when a delivery should be assisted. Labor is divided into 3 stages. Stage 1 begins with uterine contractions and dilation of the cervix and ends with passage of the amnion and part of the fetus into the vagina. Stage 1 may last 1–24 hr, with 1–4 hr being normal. Stage 2 is characterized by abdominal contractions due to the fetus in the vaginal canal and ends with the expulsion of the fetus through the vulva. Birth should be expected within 1–4 hr for heifers. A mature cow should calve in <3 hr if the presentation of the calf is normal; if no progress is seen within 1 hr, assistance may be required. Stage 3 is expulsion of the fetal membranes and the initiation of uterine involution. Expulsion of the fetal membranes normally occurs within 12 hr after parturition.
Feeding preparturient cows in the late morning (11:00 am–12:00 noon) and again at night (9:30–10:00 pm) encourages cows to calve during the day (7:00 am–7:00 pm), when a problem is more likely to be identified and assistance more likely to be available.
Parturition is often difficult for both fetus and dam. Many factors influence the degree of difficulty, including breed, age, nutrition, and pelvic area of the dam; breed and genotype of the sire; gestation length; and sex, size, position, and presentation of the fetus. Some, though not all, of these factors are directly influenced by management.
When dystocia (see Management of Reproduction: Cattle: Dystocia Management) develops, survival of both dam and calf depends on proper assistance. This requires identification of the problem, proper facilities, and adequate help. A delay in assisting may mean the loss of the calf or injury and even death of the cow. However, it is important to allow sufficient time for the dam to dilate before applying traction. Before assisting the delivery, the position of the fetus must be determined accurately, and any abnormal presentation corrected. If the calf is simply too large to pass through the birth canal without danger to the cow or calf, a cesarean section or other surgical assistance may be necessary.
Management After Calving
Muddy lots, crowding, filth, chilling, and inclement weather make the calf more vulnerable to disease organisms and may result in sickness and possibly death for both dam and calf. (Also see Health-Management Interaction: Cattle and see Management of the Neonate.)
Calves receive immunity passively from the dam through the ingestion of colostrum. The calf's immune system is immature at birth and depends on acquisition of passive immunity for disease protection in early life. Immunoglobulins (IgG and IgM) and lymphocytes are absorbed directly across the gut into the calf's circulation to provide immunity. The ability of the gut to absorb these large molecules and cells is a transient phenomenon; gut closure is complete by 24 hr, and absorption has decreased significantly by 6–8 hr of age. Ingestion of adequate amounts of quality colostrum as early as possible after birth is important for calf survival and growth. Calves with failure of passive transfer (FPT) are 3–9 times more likely to become sick before weaning, and 5 times more likely to die before weaning than calves with adequate passive transfer.
Minimizing the incidence of FPT should emphasize dystocia management, proper nutrition, and intervention for calves at high risk of FPT. Cows that have dystocia should be milked out immediately and the calf force-fed colostrum to ensure ingestion. Cows with poor udder conformation or mastitis should be milked and the colostrum fed to the calf to ensure timely intake. Colostrum supplements have not proved useful in controlled clinical trials in elevating serum IgG levels. Vaccination of the cow before calving with pathogens causing enteric disease in calves may be a useful adjunct to good overall management in reducing morbidity.
Last full review/revision July 2011 by Carlos A. Risco, DVM, DACT