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.
novyi, infrequently called Black disease, in cattle, occur sporadically in cow-calf operations as they are more often seen under feedlot conditions. The route of infection and transmission are not known, however, it is thought to gain entrance into the body by a wound infection, or possibly taken in orally.any of the organisms in this group are also normally present in the intestines of man and animals. Black Leg Blackleg is a disease caused by Clostridium chauvoei and primarily affects cattle under two years of age and is usually seen in the better doing calves. The organism is taken in by mouth.