VARYING LEVELS OF STARCH IN CALF MILK REPLACERS

Starch replaced varying amounts of lactose 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. Amylopectin comprised 0, 9, 18, and 27% of solids in the replacer. Daily gains (3 to 45 days) for the respective treatments averaged 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 amylopectin 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 compared the same rations as Trial 1 in a digestion and nitrogen balance study with 16 bulls. Collections were made at 10, 24, 38, 52, and 80 days of age. Significant decreases (P < .01) in dry matter, carbohydrate, and protein digestibilities were noted as dietary starch increased. Starch digestibilities averaged 79% compared to 98% for lactose in the control diet. Starch digestibilities increased markedly between 10 and 24 days of age; whereas, a linear increase with age to 80 days was noted for protein digestibilities. © 1968, American Dairy Science Association. All rights reserved.