The Influence of Pasture and Early Rumen Development on the Changes in the Plasma Carotenoids, Vitamin A and Ascorbic Acid and the Liver Storage of Carotenoids and Vitamin A of Young Dairy Calves

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Abstract
The favorable results obtained from feeding relatively large amounts of good quality hay, coupled with rumen inoculations, as a means of initiating early rumen function and meeting some of the vitamin needs of young calves, suggested the feasibility of utilizing pasture, when available, in young calf feeding. In an earlier communication (2), the changes in the blood plasma carotenoids, vitamin A and ascorbic acid during the first 6 wk. in calves fed milk and alfalfa hay with and without grain concentrates and with and without rumen inocu- lations with cud material from older cattle were presented. Calves fed on a ration consisting of whole milk and alfalfa hay had a much higher blood plasma carotenoid level than calves fed the same ration plus grain concentrates free choice. Little, if any, difference in plasma vitamin A was shown between the two groups. No effect from rumen inoculations could be detected in either the plasma carotenoids or vitamin A. However, a higher, more uniform level of ascorbic acid was maintained in inoculated calves fed only milk and alfalfa hay than in the uninoculated calves fed the same ration. In accompanying reports (5, 6), the influence of the ration, including vari- ous proportions of grain concentrates to roughage ingestion, on the establishment of certain rumen microorganisms was shown. This report presents the results obtained from feeding young calves on pasture with variations in supplemental hay and grain feeding and rumen in- oculations. The changes in the blood plasma carotenoids, vitamin A and as- corbic acid, liver storage of carotenoids and vitamin A and the gain in body weight are included. The influence of pasture and rumen inoculations on the establishment of certain rumen microorganisms in the same calves is pre- sented in an accompanying paper (7). EXPERIMENTAL
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