Summertime ills Dr. Doug Mann | Back to Vet Advice
Late spring and early summer is the time for cattle to be turned out to grass to fend for themselves. The cattle producer can relax and admire the growth and quality of their livestock during a weekly visit. Is a once-a-week check on the herd sufficient? Perhaps the cattle should be monitored more often.
Besides the common health problems such as foot rot, pinkeye and pneumonia, there are certain nutritional-related disorders that can occur when grazing forages that producers must be vigilant of. Three such problems are bloat, grass tetany and atypical interstitial pneumonia.
Bloat is characterized by a distention of the rumen when either free gas or a stable foam build up. The gas builds up to the point where pressure is exerted on the lungs and the animal suffocates. Bloat is common when grazing a lush legume (alfalfa or clover) type pasture.
Prevention of bloat can be achieved by management practices such as never placing empty and hungry cattle on lush pastures. Feed additives such as Rumensin or a water additive such as Alfasure are also highly effective. For a more comprehensive prevention and treatment protocol, it is advisable to contact your local veterinarian prior to grazing alfalfa. Alfasure is a new product that is available for the first time this month. It is distributed through veterinarians and so far is only available in Canada. It's a polymer-based product sold in 20-L pails and is administered through a medicator in the water line. The daily dose is set between six and 20 mL per day depending on how much water the cattle are drinking and the condition of the alfalfa they are grazing. For more details contact your local practitioner or the manufacturer Rafter 8 in Calgary at 800-461-8615.
Atypical interstitial pneumonia (AIP) is a respiratory condition that occurs usually seven to 10 days after placing cattle on lush pasture. A chemical reaction occurs in the rumen which then causes the normal transfer of oxygen in the lungs to be impaired. Often, these animals are found dead or panting with the mouth open. Treatment involves changing pasture and using drugs that reverse what is happening in the lungs. It is therefore especially important that your veterinarian examines any sudden deaths at pasture.
Grass tetany occurs most commonly in lactating animals grazing a lush pasture. The condition is caused by a lack of magnesium in the animals. A cow loses magnesium in her milk. Therefore, if inclement weather or transport interrupts her intake of forage, her body is losing magnesium faster than it is taking it in. Another way to get low magnesium is if the cow is grazing on heavily fertilized forages, as magnesium absorption from the rumen is reduced when nitrogen and potassium intakes are high. The cow will show nervous signs such as hyperexcitability, muscular spasms, convulsions, recumbancy and death. Treatment involves intravenous solutions of magnesium. Prevention involves supplementation of the diet with magnesium oxide. Your veterinarian can advise both treatment or prevention programs for you.
In conclusion, once the cows go to pasture, it is still important to check the herd often. Discuss preventative health and management programs with your local veterinarian, as they are the most knowledgeable about your operation and the local environment. Have post-mortems performed on all unexplained deaths, both cows and calves.
