Varying Levels of Starch in Calf Milk Replacers

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Abstract
Starch replaced varying amounts of lac- tose in milk replacers fed to Holstein calves by nipple pail as the only source of nutrients in three trials. Trial 1 was a growth trial involving 28 heifers. Amylo- pectin comprised 0, 9, 18, and 27% of solids in the replacer. Daily gains (3 to 45 days) for the respective treatments av- eraged 0.50, 0.45, 0.35, and 0.36 kg/day and were significantly lower (P < .05) for the two highest starch levels: In Trial 2, 30 heifers were used to compare two levels (14 and 28%) of amylopeetin or corn starch. Daily gains were lower in all the starch diets than in the control.:' There was little difference due to starch " source or level. In Trials 1 and 2, most of the growth depression due to starch occurred during the first three weeks. Trial 3 com- pared the same rations as Trial I in a di- gestion and nitrogen balance study with 16 bulls. Collections were made at 10, 24, 38, 52, and 80 days of age. Significant de- Greases (P < .01) in dry matter, carbohy- drate, and protein digestibilities were noted as dietary starch increased. Starch di- gestibilities averaged 79% compared to 98% for lactose in the control diet. Starch digestibilities increased markedly between 10 and 24 day s of age; whereas, a linear increase with age to 80 days was noted for protein digestibilities. Poor growth in young calves has resulted from feeding milk replacers containing a high percentage cereal product (3, 5, 12). Even though pancreatic amylase and intestinal mal- tase are present in the postruminal digestive tract of the young calf, low activities of these enzymes have been associated with the inef- ficient gains observed on starch-containing feeds (4, 6). Absorption studies have also in- dicated poor utilization of starch introduced postruminally (7, 8, 11). The objectives of this investigation were to determine the maximum level of starch that tan be incorporated in milk replacers without