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.
Among the various classes of cattle and calves, calves aged from 22 days through weaning were the animals vaccinated most commonly; 62.3 percent of operations vaccinated some calves in this age group for some disease agent.mong the various classes of cattle and calves, calves aged from 22 days through weaning were the animals vaccinated most commonly; 62.3 percent of operations vaccinated some calves in this age group for some disease agent.