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.
If a newborn calf is unable to nurse its dam, use of a surrogate cow may be the best way to raise the calf until weaning. Bottle-fed calves can be weaned after one month of age, while calves nursing cows are weaned between 3 and 8 months of age. It is usually best to wean at the older age.For comparing weight of calves weaned at different ages, a 205-day weaning weight is sometimes calculated.f a newborn calf is unable to nurse its dam, use of a surrogate cow may be the best way to raise the calf until weaning. Bottle-fed calves can be weaned after one month of age, while calves nursing cows are weaned between 3 and 8 months of age. It is usually best to wean at the older age.