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.
In a severe drought calves can be weaned as early as six weeks if they are placed on a high protein (18 per cent) concentrate diet and carefully managed. Weaning at this stage will conserve the body condition of the cows, stimulate oestrus activity, ovulation and ensure reasonable conception rates at joining.alves are generally weaned between 8-10 months of age. The actual age depends on several factors: 1  Feed availability-cows can continue lactation without losing condition in good years, but early weaning should be considered in drier years.