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 foundation for each vaccination approach discussed below is the administration a 7- or 8-way clostridial vaccine at 2 to 3 months of age (branding), plus a modified-live virus (MLV) vaccine given at the same time for viruses commonly associated with bovine respiratory disease (BRD) complex.ption B is designed for calves processed 3 to 4 weeks before weaning, then shipped the day of weaning. This option is preferable to Option C because it allows time for the calves to maximize immunity in response to the booster vaccinations they received 3 to 4 weeks before weaning.