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.
The following table illustrates the difference in the cost of feed and labor for weaning a calf at 5 or 8 weeks of age. This example represents estimated prices for a good quality milk replacer and calf starter. Under these circumstances, weaning a calf at 5 weeks instead of 8 weeks saves $26.89 per calf.