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American and Canadian studies have found that up to 5.6 % of all calves born alive die before weaning.
Dystocia is a major cause of death, but diarrhea and respiratory disease together rank second.
Thirty-six percent of Canadian herd owners reported problems with calf pneumonia, which shows it is a major concern among producers.
Though suckling claves suffer fewer cases of pneumonia than feeder calves, it still has a significant economic impact. Sale at weaning is the primary source of income for cow-calf operations, and pneumonia negatively affects the number of calves and final weight of calves sold.
The key is to identify the risk factors that can promote pre-weaning respiratory disease. On significant risk is dystocia.
Offspring that have undergone a dystocia have 13 times greater odds of dying than calves born without difficulty. Preventing dystocia significantly reduces the risk of pre-weaning disease and death.
Age segregation and adjusting the timing of calving season are two basic management techniques for controlling pre-weaning pneumonia.
The temperatures and weather conditions that predominate when calves are born influence mortality. Low temperatures tend to increase pre-weaning mortality while warmer temperatures decrease it. Timing the calving season to match milder weather helps boost calf survival.
However, the timing of a calf’s birth with in the calving season also plays a role.
Probability of death from diarrhea increases for calves born at the end of the calving period, presumably because of increased exposure to pathogens.
The same reasoning explains why we see more respiratory disease late in the calving season.
Segregating calves so they are housed with calves their own age helps limit this exposure. As well, feeding so that adult cows don’t congregate in small areas for long periods of time helps decrease a calf’s exposure to high pathogen loads and increase calf survival.
Diarrhea and pneumonia affect different ages of calves.
Diarrhea caused by E. coli tends to strike in the first week while viruses and cryptosporidium afflict calves up to a month old. Pneumonia, on the other hand, peaks in calves 70 to 170 days old.
This means the focus on respiratory disease must continue right through to post-weaning and not just early in life.
Because calves are so dependent on antibodies obtained from colostrum, producers can help decrease illness from respiratory disease and other ailments by ensuring adequate and early consumption.
A further challenge in pre-weaning management is vaccination timing. You don’t want to vaccinate too early because antibodies obtained from colostrum can interfere and prevent an immune response. Conversely, a delay in vaccination means the calf has a period of susceptibility to the disease.
The type of vaccine also plays a role. Vaccines given intranasally have been found to protect against clinical challenge better than injected vaccines when studying BHV-1, the cause of infectious bovine rhinotracheitis.
Calves receiving an intranasal vaccine did not become febrile, were not dyspneic (laboured breathing), did not cough and had no nasal discharge, while calves receiving the injected product had at least on clinical sign when challenged.
Calves given an intranasal vaccine do not produce an antibody response detectable in the bloodstream, which is the standard way to measure a vaccine response. Blood antibody levels obviously do not give a complete picture of immunity.
Jeff Grognet is president of the British Columbia Veterinary Medical Assoc. and is practicing in Qualicum Beach, B.C.
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Congratulations to Lee Stringer who was presented the 2008 Robert Owen Memorial Award. For over 20 years, Lee and his wife Bonnie have supported and dedicated their time to the Alberta Texas Longhorn Association in raising and promoting Texas Longhorn cattle. 
For this years 4-H project Kelsy Hepfner continues with another Longhorn Angus heifer. During her Beef Achievement day on May 27, Kelsy placed 3rd in the heifer conformation class. The judge commented that she has an outstanding heifer with many good qualities that will go on to make a good cow. Kelsy was also awarded the top Female Record Book for the Telford 4-H Beef Club. Keep up the good work and we hope you continue to show how wonderful the Texas Longhorns cross with other breeds of cattle.
