Experts target sheep mortality

Respiratory disease and digestive problems account for more than half the overall deaths in sheep flocks.  |  File photo

RED DEER — A long-time cattle veterinarian has learned after a short time working with sheep that the two species are very different.

As an epidemiologist and owner of Alberta Beef Health Services, Joyce Van Donkersgoed has also discovered that the sheep industry does not have many effective treatments for the diseases she sees at a southern Alberta feedlot.

“One of my frustrations as a veterinarian is that there is very limited help out there,” she told the Alberta Sheep Symposium held in Red Deer Oct. 15-16.

Lambs arrive at the feedlot without much health history. They often succumb to disease faster than feedlot cattle, so she conducts necropsies when they die to see what went wrong and learn how to control or prevent future problems.

The industry considers feedlot lamb losses of three percent to be the norm, but she considers that death rate to be high.

Producers finishing their lambs on the farm or at a feedlot need to consider the value of a market animal and determine the cost of saving it.

“If you have a small operation with 36 ewes and you lose half a percent of your feeder lambs, is that something to get excited about? Do you want to do something different to reduce that death rate, and how much is it going to cost you to figure out why they die?” she said.

Van Donkersgoed is working with pathologists at Alberta Agriculture and microbiologists at Prairie Diagnostic Service to determine the causes of death in commercial lambs. This could help reduce mortalities and improve overall health of the flock.

The findings will be shared with the sheep industry and small ruminant veterinarians to help them make better diagnoses of feeder lambs.

A grant from the Alberta Livestock and Meat Agency (ALMA) will fund post mortems over a one year period in a commercial lamb feedlot.

She advises producers to keep written records of treatments, number of deaths, causes and on-farm activities at the time of death.

Van Donkersgoed has determined that pneumonia is a leading cause of death, and lambs die quickly once they are infected. Most forms are acute.

There are no licensed bacterial or viral vaccines in North America to prevent pneumonia in sheep. Using drugs designed for cattle will not work because the bacterial strains are different. As well, withdrawal periods to prevent antibiotic residues are long.

“You as a producer must work with your veterinarians in what is called a patient veterinary relationship to actually use these products. Your veterinarian has to have knowledge of your sheep before they can actually prescribe these products,” she said.

“If you use one of these products without a prescription, you are actually breaking the law.”

Processors may ask for an affidavit to show that the animals have passed the drug withdrawal period to avoid residues in the meat.

Lambs can get serious bacterial infections, but they can also die from an anaphylactic reaction to a drug. The flock veterinarian should be informed if that happens.

Vaccines would be helpful but nothing is approved in North America at this time. As a result, scientists from the Vaccine and Infectious Disease Organization in Saskatoon are using funding from ALMA and national and provincial organizations to develop a respiratory vaccine for sheep. This could take three to five years.

Digestive problems account for one-quarter of the illnesses or deaths, so it is important to work with a nutritionist on ration formulation for sheep.

Frothy bloat is responsible for more than 40 percent of digestion related deaths.

Gas bloat and grain overload also happen, especially when more grain is added to rations.

Frothy bloat is often linked to feeding alfalfa hay. A feedlot does not know the lamb’s history, and some may never have eaten alfalfa.

Lambing mortalities can happen in a feedlot.

“Something that is really hard to deal with is lambing mortalities,” she said.

Some young ewe lambs may arrive pregnant, and a feedlot does not have the facilities to care for them if they survive. Pen checkers may not realize the ewe is pregnant until it is too late, and the young animals may not be monitored at night when lambing may occur.

Uterine or vaginal prolapses may occur after lambing. Animals with these conditions may die of infection or bleed to death.

Producers need to keep male and female feeder lambs separate to avoid unwanted pregnancies.

Rectal prolapses may also occur. Potential causes include cutting tails too short, diarrhea, coccidiosis, worms and feed overload.

Injuries contribute to five percent of deaths seen at the feedlot, including broken legs, toe abscesses, suffocation, bleeding to death from wounds and cellulitis, which is an infection under the skin.

Injury prevention can start at the farm and when animals are shipped to a feedlot or market. Try to use certified livestock transporters who practice low stress handling, do not use electric prods and do not overcrowd trucks.

“We encourage anyone who hauls sheep to take this course.”

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