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 cost of providing minimum vaccination requirements â blackleg, BVD, and bacterial pneumonia â is $15.60 per cow-calf pair. Table 1. Typical herd diseases to vaccinate against & per dose cost Covexin-8 Spring Spring Bacterial Pneumonia a Pour-on rate 1 mL per 22 lb; based on 5 L pour-on for 1200 lb cows.f your farm or area has had anthrax cases, it is recommended that you vaccinate every year for several years. Community Pasture Requirements If you are a community pasture patron, you are required to treat all cattle under two years of age with a blackleg vaccine (SK Ministry of Agriculture 2008).