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.
Solid feed intake should be gradually increased as the calf grows so that the weaning process becomes much more straightforward. Bucket fed calves can be weaned abruptly provided they are at least 5 weeks of age and consuming a minimum of 1kg (2lb) of concentrates per day.