FEED CONSUMPTION AND GROWTH OF DAIRY HEIFER AND BULL CALVES FED CALF STARTERS DIFFERING IN PROTEIN CONTENT

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Abstract
Four groups of five Holstein heifer calves were fed calf starter ad libitum from the 5th through the 16th wk. Diets differed in crude protein (CP) content (9.3, 17.8, and 22.2% CP) and were compared to a 21% CP, high-fat milk replacer (HFMR) during 28-day periods. Voluntary intake was not affected by starter CP content. However, increasing dietary CP content increased gains and feed efficiency. Gains were similar between the high-protein starter and the HFMR. When calves in one group received a different starter each day, voluntary consumption of the low-protein starter was reduced. In the second experiment, the HFMR and a starter containing either 10.6, 15.3, or 22.8% CP were fed to Holstein bull calves from wk 2 through 4. The starters were each fed for 21-day periods to each group of calves after weaning from HFMR. A fourth group received a starter of different CP content each day. A fifth group received only HFMR for the entire period. After the 4th wk, calves fed HFMR consumed less dry matter (DM) but gained weight most rapidly. Average daily gains were increased by the medium- and high- over the low-protein calf starter (P < 0.05). Feed efficiency was subsequently reduced by this diet. A ration containing no more than 18% CP was satisfactory for dairy-replacement heifers. However, additional studies should examine the feasibility of marketing 136-kg calves on high-energy calf starters.