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.
All 11â12 year olds should be vaccinated with a quadrivalent (protects against serogroups A, C, W, and Y) meningococcal conjugate vaccine (MenactraÂ® or MenveoÂ®). A booster dose is recommended at age 16 years.For teens who receive the first dose at age 13 through 15 years, a booster dose should be administered, preferably at age 16 through 18 years, before the period of increased risk.he minimum interval between doses is 8 weeks. However, teens who receive their first dose of quadrivalent meningococcal conjugate vaccine at or after age 16 do not need a booster dose.