Amino Acids, Fatty Acids, and Fat Sources for Calf Milk Replacers

Three trials were conducted to examine the effect of including specific amino acids, fatty acids, and fat sources in 20 and 22% CP and 20% fat milk replacers (MR; as-fed) fed at 454 g daily. Trial 1 measured selected blood constituents in calves fed a 20% CP, 20% fat MR including all added fat from lard and no added synthetic amino acids (CON20); a MR with added butyrate (BUT20); a MR with added coconut plus canola oil (FB20); and a MR with added L-Lys plus DL-Met (LM20). Trial 2 compared CON20, LM20, and a MR with 22% CP (CON22). Trial 3 compared CON22, a MR with 20% CP with added Lys and Met, 20% lard, coconut, and canola fat with sodium butyrate (MOD20), and pasteurized whole milk at the equal rates of DM. Compared with calves fed CON20 in Trial 1, amylase increased (P < 0.05) and urea-N decreased (P < 0.05) in calves fed BUT20; alkaline phosphatase increased (P < 0.05), creatinine tended to increase (P < 0.10), and urea-N decreased (P < 0.05) in calves fed FB20; and urea-N decreased (P < 0.05) in calves fed LM20. Calves fed LM20 in Trial 2 grew faster (P < 0.05) than calves fed CON20. In Trial 3, the calves fed MOD20 grew faster (P < 0.05) than calves fed CON22 or whole milk and had fewer abnormal fecal score days (P < 0.05) than calves fed CON22. Calves fed 20% CP MR formulated with considerations for fatty acids and amino acids grew faster than calves fed either 20% CP MR or pasteurized whole milk.