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Weak Calf Syndrome

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Grant Dewell, DVM, Reneé Dewell, DVM, and Terry Engelken, DVM
Veterinary Diagnostic and Production Animal Medicine
Iowa State University

Weak Calf Syndrome (WCS) typically describes calves that are born alive, but lack normal vigor. Many of these calves die shortly after birth. Often, affected calves cannot stand and nurse by themselves. If they do stand, they are very slow in getting up and often adopt a hunched posture. Herds affected with WCS may also have stillborn calves. With intensive management, some weak calves may survive. The Iowa State University Veterinary Diagnostic Laboratory has received reports of weak calves from producers and veterinarians. Unfortunately, it is difficult to correct a WCS problem in a herd after it has been identified with the birth of one or more weak calves. There are multiple factors that may contribute to WCS during gestation including suboptimal dam nutrition, mineral deficiencies, and infectious diseases. Unfortunately, the inciting cause of WCS is not always diagnosed.

Ultimately, optimal dam nutrition is the best management intervention to prevent WCS. Pre-partum nutrition is key for preparing the calf for life outside the uterus. Up to 80% of fetal growth occurs in the last 50 days of gestation. Therefore the dam needs adequate nutrition to support the tremendous growth of the fetus while supplying enough additional nutrients to the calf so that it has enough reserves to be able to stand and nurse after birth.

Producers should have their winter hay evaluated to determine the nutritional quality- especially since summer 2009 conditions resulted in poorer quality hay compared to a typical year.  Feeding the same amount of poorer quality forage means that cows may not be getting adequate nutrition.  Also severe cold will increase cow maintenance requirements as they burn calories to keep warm. A good rule of thumb is to manage the feeding program so that cows are at a Body Condition Score (BCS) of 5 (6 for heifers) prior to calving.  Heifers are more prone to producing weak calves and their BCS should be carefully monitored.

Protein is one of the biggest nutritional components necessary for fetal development. Calves born from protein restricted dams have decreased calf vigor, decreased thermal heat production, and increased time from birth to standing. Early research in Idaho indicated that adequate protein during gestation would decrease the incidence of weak calf syndrome.  Late gestation cows need 2 lbs of protein per day. 

Energy is also important for the fetal calf. Fetal brown fat supplies the energy needed for the calf to survive until adequate colostrum and subsequently milk is ingested. Cows need at least 11 Mcal of energy per day. However, producers should consider increasing energy intake because of this year’s extreme cold weather. Producers need to adapt and feed their cows to fit the environmental conditions. It is important to recognize that although pregnant cows can be roughed through much of the winter, this practice should not include late gestation. Calves born to cows that were losing weight during late gestation will have lower energy stores and longer interval from birth to standing. Additionally, these cows will take longer to breed back.

Selenium and Iodine deficiency may also be associated with WCS.  If you are in area where selenium is deficient supplemental sources may be necessary.  Once supplementation starts, it will take approximately 4-6 weeks to build adequate selenium levels in the liver of the cow. However, weak calves can still be observed when selenium is adequate and supplemental selenium in these instances is not beneficial.

Infectious causes of WCS include Bovine Viral Diarrhea Virus (BVDV) and leptospirosis. BVDV is capable of causing multiple congenital problems in calves.  The particular problem seen in calves will depend on the stage of gestation the cow was in at the time of infection. Calves infected in-utero may show signs of hydrocephalous, immaturity,” dummies”, or generalized weakness. Stillborn calves that are found dead without evidence of dystocia should be investigated by you and your veterinarian. If any of these organisms are suspected contact your veterinarian to ensure that the correct diagnostic samples are submitted and the test results are used to re-evaluate your herd health program

Weak Calf Syndrome

Producers should also focus on good management practices during calving. In general, birth is a traumatic event for the calf and dystocia can further exacerbate problems. Dystocia calves will usually have decreased calf vigor, appear weaker at birth, and take longer to stand up and nurse.  Additionally, excessive hypoxia (low blood oxygen) during the birthing process can cause temporary or permanent injury to the central nervous system. As always, a clean dry calving environment helps the calf get off to a good start. A calf that is born into a cold wet environment is going to have to spend more energy keeping itself warm before it ever has a chance to stand and nurse. If calves have not stood and nursed within 4 hours the dam should be restrained, milked out and the colostrum fed to the calf.

Weak calf syndrome needs to be addressed well in advance of the calving season. Factors such as cow herd nutrition, micromineral balance, dystocia levels, and various disease organisms can all play a role in producing this condition. Unfortunately, the cold weather has already had a negative impact on the cow herd and the nutritional program during late gestation has already determined the BCS for those cows calving now. A solid herd health program and proper nutritional management are two critical components that impact both calf survival and subsequent pregnancy rates. Now is the time to pay close attention to female body condition score and calf vigor. Then work with your veterinarian and extension specialists to put a plan together to minimize losses now and prevent losses in the future.  


 Dr. Grant Dewell

Dr. Grant Dewell

Veterinary Diagnostic and Production Animal Medicine
2412 Lloyd Vet Med
Iowa State University
Ames, IA  50011

Ph: 515-294-2822
Fax: 515-294-1072