Effect of vitamin B12 (A.P.F.) on the growth of calves weaned from milk at an early age.

V ITAMIN B12 per se or animal protein factor containing B12 concentrate has been shown to have growth-promoting activity for poultry (Johnson, 1949; Richardson et al., 1949) and swine (Catron and Culbertson, 1949; Catron and Wallace, 1949; Hogan and Anderson, 1949), and increased feed efficiency for these species. I t is well known that cow manure (Whitson et al., 1945; Rubin and Bird, 1946; Lillie et al., 1949) and sheep feces (Abelson and Darby, 1949) are potent sources of the A.P.F. or vitamin B~2 in growth-promoting activity for poultry. Ruminants probably obtain this factor either by rumen or intestinal symbiosis or from their ration. However, no research has been reported in the literature as to its growth-promoting effect on calves weaned from milk at an early age. Johnson (1950) in a preliminary report stated that the calf requires vitamin B12. According to Hartman, Dryden and Cary (1949), milk contains a growth-promoting factor "Factor X" which is related to vitamin B12. Collins, Dietrich and Elvehjem (1950) have reported that cow's milk contains 2-3 t~g. of vitamin B12 per liter. Thus, vitamin B12 is supplied by the diet of young calves since they consume milk or milk products during their first few weeks of life. After weaning from milk at a very early age it is possible that a vitamin B12 supplement may be necessary in the calf starter until the calf rumen has developed and is functioning normally so that rumen synthesis of vitamin B12 occurs. This research was conducted to determine whether the addition of a vitamin Blz concentrate (A.P.F. No. 3) to an all-plant protein calf starter is of value in increased growth "activity and ,increased feed efficiency when calves are weaned from milk at 28 days of age.