In geography and fluvial geomorphology, a thalweg or talweg (/ËtÉËlvÉÉ¡/) is the line of lowest elevation within a valley or watercourse. Under international law, thalwegs can acquire special significance because disputed river borders are often deemed to run along the river's thalweg. 1 Etymology.
However, when they are 3 to 4 months old, they become susceptible to the disease, so all calves should be vaccinated for blackleg by 4 months of age. A revaccination 3 to 6 weeks later according to product label directions is necessary to provide the best protec-tion.lackleg seldom affects cattle older than 2 years of age, most likely due to immunity induced by vaccines or natural exposure. However, sporadic cases do occur in cattle older than 2 years and are often associated with the reuse of needles for multiple injections.
The effects of exposure can be minimized if care is taken to ensure calves nurse soon after birth. In addition, during extremely cold or wet conditions calves may need shelter for the first 24-48 hours of life.Chilled calves should be brought in for warming and assisted in nursing if necessary.ll calves should be checked to see if they have nursed within 2 to 4 hours of birth. Calves that have not nursed should be assisted or tube fed colostrum with a special calf feeder. Calves need 1 to 2 quarts of colostrum.