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.
Many producers don't give clostridial vaccines to calves until they are at least 3 to 4 months of age, and then we try to make sure they get a booster after that. If a herd has a history of problems in young calves, we recommend clostridial vaccines be given soon after birth, Alley says.accinating with these antigens should be discussed with your veterinarian before using them in young calves. As long as the passive transfer is still strong, the calf may not build its own immunity. Some vaccines have been shown to provide some immunity at an early age, even in the presence of maternal antibodies.