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.
Thatâs especially true when it comes to the leg labeled health, and thatâs reason enough, Baker says, to consider vaccinating your calves at branding or turnout. Traditionally, the recommendation has been to wait until calves are at least four months old before administering any vaccines. That way, goes the conventional wisdom, thereâs a reduced chance that the antibodies in the colostrum will cancel the effects of the vaccine.