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The Cow-Calf Manager
Livestock Update, March 2005
John B. Hall, Extension Animal Scientist, Beef, Virginia Tech
Calving Management Reduces Calf Losses
Calf losses at calving time are very distressing for cattle producers, and hard on profits. Data from various IRM programs indicates that 2.0% to 5.0% of the calf crop is lost at calving time. Except in years of extreme disease outbreaks or blizzards, this makes calf losses within 24-48 hours of birth the number two cause of reduced calf crop after open cows. Quite often what appears as a stillbirth or a mysterious calf death can be prevented by management at calving time.
Preventable losses include dystocia (calving difficulty), prolonged labor, weak calves, calves failing to nurse, and hypothermia. In other Cow-Calf Manager articles, we have discussed the importance of nutrition in late gestation on calf vigor and future cow reproduction. However, let's concentrate on management aspects at calving.
Check cows often because labor is over sooner than you think
It is recommended that cows be observed 3 times per day and heifers 4 to 5 times per day. Understanding the duration and signs of labor is important to identifying calving problems and intervening in a timely manner. Frequent observation will prevent calf losses due to dystocia and prolonged labor as well as failure to nurse.
Labor and delivery usually lasts less than 8 hours. Labor is divided into three stages with all three stages only lasting 6-12 hours. Cows and heifers can attempt to calve and fail in the time it takes us to perform our off-farm job or other tasks around the farm. Tasks like planting and harvest often occupy 10-12 hours of the day. Understanding the stages of labor will help you in making decisions on assisting during delivery. Table 1 details the three stages of labor.
The first stage of labor we'll call the Preparation stage. During this stage contractions begin, but they are mild and spaced fairly far apart. The contractions become more coordinated and stronger as the first stage progresses. The primary purpose of the first stage is to force the calf and fetal membranes toward the birth canal and dilate the cervix. Cows and heifers will often appear nervous and isolate themselves from the rest of the cowherd during this stage. These expectant dams can often be observed lying down and getting up often. They are obviously uncomfortable. The preparation stage ends with the emergence (and sometimes breaking) of the fetal membranes or Òwater bagÓ. This stage will last 2 to 6 hours.
The second stage of labor is Delivery or "hard labor". During this stage contractions are strong and coordinated. The fetal membranes and then the calf are forced into the cervix or birth canal. During this stage cows and heifers will often lie on their side and will be visibly straining. Calves are born with the dam either lying or standing. Normal presentation is the front feet first with the head between the knees and shoulders. Any other presentation is a signal that assistance is needed. It is not unusual for the feet to appear and disappear several times during the early part of delivery. However, definite progress towards delivery should be made within 1/2 hour from appearance of the feet or cows should be checked. The second stage ends with the delivery of the calf. Normally this stage should last 1 to 2 hours in heifers and 1/2 to 1.5 hours in cows. If the second stage lasts longer than 2-3 hours, cows should be checked.
The final stage of labor is Cleaning or passing of the afterbirth. The continued contractions of the uterus expel the remaining fetal membranes. The third stage of labor lasts 1 to 8 hours. Cows not cleaning within 12 hours of birth of the calf are considered to have retained placenta. Cows with retained placenta should be treated with antibiotics as suggested by your veterinarian.
Table 1. Stages of Calving
| Stage and time | Events |
|---|---|
| Preparatory Ð Stage 1 (2 to 6 hours) | 1.Calf rotates to upright position. 2.Uterine contractions begin. 3.Water sac expelled |
| Delivery Ð Stage 2 (1 hour or less) | 1.Cow usually lying down. 2.Fetus enters birth canal. 3.Front feet and head protrude first. 4.Calf delivery completed. |
| Cleaning Ð Stage 3 (2 to 8 hours) | 1.caruncle-cotyledon (button) attachments relax. 2.Uterine contractions expel membranes. |
Total impact of calving difficulty greater than imagined
Incidence of calving problems. In most herds that choose moderate to low birth weight EPD bulls for their cows, calving problems (dystocia) run about 1 to 5%. However, in first-calf heifers, dystocia runs 5 to 20% even in herds that use low birth weight EPD bulls. Incidence of dystocia in herds that don't pay attention to birth weight EPD's of sires can run as high as 50 to 75%. That's why heifers need extra observation. In addition, heifers don't necessarily give as good an indication that they are beginning the calving process.
Calves that experience calving difficulty are less healthy. Delay during delivery cause calves to be more susceptible to illness or death shortly after birth. Researchers from Nebraska and Colorado indicated that mortality is increased by 15 to 30% in calves that experience calving difficulty. In addition, calves will take longer to get up and nurse if they experience a difficult birth.
Cows and heifers that experience calving difficulty will be delayed in rebreeding. Two studies with 220 cows in Montana examined the effects of assisting cows at the first sign of calving problems with letting cows struggle before assisting. In these studies, calf growth rate was not affected by duration of labor. However, cows and heifers, that were assisted early, bred back earlier (Table 2.). In addition, overall pregnancy rates were decreased by 13-14% percent by allowing cows to struggle.
Table 2. Effects of duration of labor on subsequent reproduction and calf growth
| Duration of Labor | No. Cows | Services per conception | Pregnancy rate | Calf Gain Birth to Weaning |
|---|---|---|---|---|
| Short | 117 | 1.15 | 91.4% | 1.68 lbs/day |
| Prolonged | 103 | 1.24 | 77.7% | 1.75 lbs/day |
Cold stress kills calves quickly
Cold stress on calves has more lethal consequences than cows. Newborn calves are the most susceptible cattle to cold stress and hypothermia. Calves less than 2 weeks old and sick calves are also at risk. The figure below illustrates the dramatic effect cold and/or precipitation has on calf survival. The lower critical temperature (LCT; temperature when animals burn energy to keep warm) for calves is close to 60¡F with calf mortality increasing exponentially as temperatures move below 50¡F. Add a little rain or snow and the LCT moves closer to 70¡F. As little as 1/10 of an inch of rain on the day the calf is born can increase calf losses by 2 to 4%.
Strategies to reduce this stress start with keeping the cows well fed and in good body condition. Cows that calve in good body condition (BCS 5-6) have stronger calves with greater energy reserves. These cows are also less likely to run out of energy during calving and will be up drying off the calf sooner than underfed cows.
Extra diligence in checking cows for signs of calving during extreme weather conditions is also important. Calves need to nurse within 2 to 4 hours of birth or sooner during cold or wet conditions. Feeding cold-stressed calves 2 quarts of warm colostrum with an esophageal feeder (calf tube feeder) will help reduce calf losses, and give calves enough energy to nurse on their own.
A clean, well-drained calving location with windbreaks or woods will help decrease the impacts of poor weather on calves. In some cases, cows and calves may need to be moved to sheds or barns for the first day or two of the calf's life. However, cows and calves should be moved to pastures as soon as the calf is strong and eating well, usually 1 to 2 days after calving. Due to health considerations, cows should be calved out on clean pastures whenever possible; calving in barns should be avoided.
Commercial calf blankets such as the Woolover¨ blanket can increase calf survivability and gain. Research from North Dakota State demonstrated a 0.3 lbs increase in average daily gain for beef calves wearing blankets for the first 3 weeks of life. In Virginia's environment, there may not be an advantage to having calves wear the blankets for several weeks, but weak or chilled calves may benefit from wearing the blankets for a few days.
Colostrum within four hours of birth is key
Calves need to nurse within 4 hours of birth. In order for calves to absorb antibodies from colostrum, they need to nurse within 12 hours of birth. However, research from Colorado State demonstrated that calves that nurse within 4 hours of birth have higher antibody levels and a lower incidence of scours and respiratory disease. In addition, calves that get sick early in life have lower weaning weights and decreased performance in the feedlot. So calves need to be checked to insure they have nursed.
Calves that have not nursed should be fed one to two quarts of colostrum through a tube or esophageal feeder. Colostrum needs to be warmed to at least 98¡ F, but should not be over 102¡ F. If colostrum is too cold it will decrease calf body temperature.
Weak calves can be a result of poor pre-calving nutrition of the dam, hypothermia, dystocia or prolonged labor. These calves don't have enough energy reserves to get up and nurse. If not tube fed and assisted these calves usually die within a day of birth. After the initial feeding, weak calves need to be monitored to make sure they continue to nurse every 2 to 4 hours. These calves my need assistance to stand and nurse their dams for the first one or two days of life.
Hints for easier calving checks and calving assistance