“Weak Calf Syndrome” is a term applied to a calf born alive but lacks vigor, is slow to stand, and may not attempt to nurse. Affected herds may also see an increase in stillborn calves. The known factors contributing to the development of weak calves include inadequate nutrition for the dam during pregnancy, difficult calving (known as “dystocia”) and infectious diseases, especially BVD virus. With excellent management, some weak calves will survive but most will die shortly after birth. Those that survive are prone to develop scours or pneumonia, grow slowly and have lower weaning weights. Although this situation is difficult to correct during calving season, identification and correction of the underlying problems will help prevent this syndrome down the road.

1. Inadequate Pre-Partum Nutrition

Nutrition for the dam is key to preparing a calf for life outside the cow. Not only does the pregnant cow’s diet need to meet her own maintenance needs but, in the last 50-60 days of gestation, approximately 80% of fetal growth occurs requiring additional nutrients to support this tremendous growth and to develop the fetal brown fat needed to supply energy to the newborn until adequate colostrum is ingested.

The two most important cow nutritional requirements are protein and energy, the exact amounts of each depend on stage of production, environment, and mature cow size. Research has shown that calves born to cows on inadequate diets have less vigor, less brown fat stores, less ability to warm themselves, and it takes a much longer time for them to stand after birth. Heifers and old or thin cows are more likely to have weak calves as they simply cannot compete for hay and feed and should be fed separately to allow them access to the nutrients they need.

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Vitamin and trace mineral deficiencies have also been associated with weak calves. If cows are not supplemented with adequate amounts of selenium during gestation, the calf will be born with a severe selenium deficiency. This deficiency results in “white muscle disease”, a condition where calves are born with weak heart and skeletal muscles and frequently die soon after birth. In addition, both vitamins A and E are vital nutrients for cows to pass to the fetus but may not be adequate in poor quality forage. Always keep a good trace mineral mix with vitamins in front of the cows or mix it in supplemental feed to ensure calves are born with sufficient amounts.

2. Dystocia (Difficult Birth)

A calf involved in a difficult birth will have decreased vigor and take longer to stand and nurse. A prolonged labor and difficult calving often results in a newborn calf with a swollen head or tongue, bruising, fractures, and excessive fluid in the trachea or lungs. Low blood oxygen in the calf (“hypoxia”) from prolonged labor will also impair the function of the central nervous system (brain and spinal cord). Additionally, a calf may have broken ribs that affect its ability to breathe. An easily observed sign of a difficult birth is brown or yellow staining of the calf’s hair coat from the meconium.

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If a calf does not stand and nurse within one hour of birth, the calf must be fed colostrum either milked from the dam or use a commercial colostrum replacement. Colostrum should be given as soon after birth as possible, preferably within 1-2 hours, and repeated at no later than 6 hours after birth. Weak calves born during cold, wet weather with little brown fat can quickly develop hypothermia (low body temperature) and are unable to stand or nurse until warmed. A warm water bath, blow dryer, heat lamp or floorboard heat can quickly warm a cold calf. Beware of heating pads as they can cause burns.

3. Infectious Causes-Bovine Viral Diarrhea (BVD) Virus and Leptospirosis

Both the BVD virus and the spirochete Leptospira interrogans serovar Hardjo infections have been diagnosed in weak calves. If an unvaccinated or poorly vaccinated cow is infected with the BVD virus during gestation, there are no good outcomes. The calf may be born weak or born with congenital defects such as a domed head, cleft palate, cataracts and other eye defects, or the calf may be born as a PI (persistently infected) calf. The other possible infectious cause of weak calf syndrome, Leptospirosis, is not fully understood but studies are on-going to determine its importance.

If pregnant cows in the herd have been losing weight, especially in late gestation, it is best to prepare for the birth of weak calves. Several measures should be instituted immediately to save as many calves as possible:

1. Check heifers and cows in labor frequently (at least 2-3 times daily) – Although producers are accustomed to watching heifers closely for calving difficulty, this recommendation should be extended to all late gestation cows. Once the water bag or hooves appear, the calf should be born within an hour to hour and a half. If the cow is not making progress, call your veterinarian for help. If early signs of labor are observed for several hours but the water bag does not appear, the calf may be breech (tail first) or abnormally positioned. Again, call for help quickly for a better chance to have a live calf.

2. Address nutritional needs and account for increased needs during severe weather. Test your hay then evaluate the protein and energy in the ration and address any deficiencies. Body condition score the cows and heifers due to calve in the next 60 days to evaluate their needs. In addition, remember that lactating cows have the greatest need for energy because they are producing milk. If you observe a young calf frequently attempting to nurse, it is unlikely to be getting enough milk from the dam and may need milk supplementation. If possible, separate cows according to their nutritional needs and feed them accordingly. Creep feeding calves will help the older calves continue to grow and lessen the burden on the lactating dams.

3. Identify the weak calves and institute special care – Normal calves should stand within 30 minutes of delivery and nurse within 30 minutes of standing. If the calf is slow to stand and nurse, intervention is necessary. It is important to dry the calf off, dip or spray the navel with disinfectant, warm the calf, and feed colostrum with an esophageal feeder to ensure it gets enough. Have a good quality commercial colostrum replacement (NOT supplement) on hand and ready to mix and feed. Do not delay because the longer the interval from birth to feeding, the fewer antibodies absorbed into the blood stream of the calf.

4. Provide shelter during harsh winter weather – Unrolling hay on the ground where there are windbreaks or in wooded areas provides some protection during times of intense rain and cold. A shed or barn can be beneficial but remember organisms that cause calf diarrhea build up very quickly in areas that stay moist and without sunlight. Barns should be clean, dry, and well-bedded if used for calving. If cows were not vaccinated with scours vaccine prior to calving, there are products available to give the calf by mouth at birth to aid in scours prevention.

5. Do your best to feed in different spots to avoid creating areas of deep mud. Calves and weak cows will get stuck in deep mud and die. Mud is very sticky and will trap weaker animals until they die of exhaustion, hypothermia or fall prey to a predator. Fields can be fixed when winter is over.

6. Diagnose the cause of unexpected death in newborn calves. Contact your local veterinarian and submit any calves that die due to unknown causes to the UK Veterinary Diagnostic Lab or Breathitt Laboratory in Hopkinsville.
The best strategies to prevent weak calves next calving season are a solid vaccination and deworming program, proper nutritional management, and avoiding dystocia. Not only will calf survival improve but pregnancy rates will increase as well. Keep the following points in mind:

Source: Dr.Michelle Arnold, University of Kentucky which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.