The retina is a light-sensitive tissue at the back of the eye and is crucial for vision. As RP progresses, the field of vision narrows, a condition known as tunnel vision until only central vision (the ability to see straight ahead) remains. Many people with Usher syndrome also have severe balance problems.
Calves can be ready for weaning by 3 to 4 weeks of age; however, in Penn State studies calves weaned at 3 weeks required extra attention. The increased time and labor required to get these calves eating starter suggest that waiting until 4 weeks of age would be prudent.
Most calves are weaned between 120 and 290 days (3 to 10 months) after birth, but most producers like to wean their calves when they're around 205 (6 months) of age.Weight is also a factor, with the minimum being generally around 132lb (60kg). Calves may have to be weaned when they are at least 120 days of age, early enough so they don't pull their dams down too much. 2  Kick the cows out to rougher pasture (or supplement them with grass hay or more marginal feeds) while you keep the calves on better pasture until sale time.