Well Mother Nature has started another drought this summer. With this time of the year comes Johnsongrass. I have already had a few calls about turning cattle in to fields with Johnsongrass. The standard answer about turning cattle into a new field is to fill them up with hay and make sure they are full before turning them into the new field. This gives us a dilution factor and will slow them down eating the new forage. If it might be toxic, the dilution factor may save them.
In toxicology everything is dose related. With some toxins a little may kill you and others may take quite a bit. If you dilute the toxin in the big vat of the rumen you shouldn’t have a problem. The only time I worry about Johnsongrass, even when we dilute it, is if we have heavily fertilized the field. The other time is when we have a rain after a drought. The young tender grass growing underneath the older stuff is very toxic. I have always conferred that if Johnsongrass is knee high it is OK.
Another point about toxicology in cattle is that when feed is short, cattle are hungry and will eat things they shouldn’t. If we can rotate pastures and keep them satisfied for feed, we really shouldn’t have a problem. But, then again what do you do when in a drought, except decrease numbers. If we can we need to keep pastures from being eaten off too bad. The more we have as quality feed, the less toxins cows will consume. This will go with eating acorns this fall, also.
Another point to make during the heat is not to get cattle over heated. Due to the thickness of cattle, if we get them overheated during the afternoon, they may not cool down until 4-6 o’clock the next morning. You are taking a chance with heat stroke and could have them die. If we need to work cattle or gather them, I would suggest doing it early in the morning or later in the evening. Temperatures should be cooler these times of the day and allow the cow to cool down easier and not during the hottest part of the day.
If we do have a cow get overheated, we need to get them to the shade and get a breeze blowing or fan on them. We can also start slowly getting them wet with water and let it evaporate. We do want to cool them slowly. Wet them down slowly and let it evaporate, wet down and let it evaporate. The evaporation will actually cool them better than anything. Normally I start wetting them down gently on the back or lower belly. Then I work up until I have the whole body wet.
Tim E. O’Neill, DVM, owns Country Veterinary Service in Farmington, Ark.
