A protein produced by cells after they have been exposed to a virus. Interferon prevents the virus from reproducing within the infected cells and can also induce resistance to the virus in other cells.
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.
RESEARCH RESULTS An important reason for weaning calves early is to allow the cow to build body reserves for the winter. Cows nursing calves that were weaned late gained 66 pounds between July 15 and September 15 (Table 1), but their gain was 31 pounds less than that of cows from which calves were already weaned.