The effect of fat supplementation of concentrates on digestion and utilization of energy by productive dairy cows.

Abstract

Two energy balance experiments each used 6 high-yielding dairy cows. In the first, a 3 X 3 Latin square with one replicate, rations were of 7 kg hay and 11 to 14 kg of concentrates having crude protein 251 g and gross energy 17.9 MJ/kg, given alone or with 5% tallow or 5% soya bean oil. Three weeks of adaptation were followed by 10 to 12 days when excreta were collected and gas exchange estimated. Digestibility and metabolizable energy of concentrates and hay were also assessed using wethers fed to maintenance only. Intakes of DM and digestibility of nutrients other than lipid did not differ among treatments with either sheep or cows. There were no apparent differences in rumen fermentation in the one cannulated cow used, and energy loss in urine was also unaffected. Lipid supplement reduced methane loss. Milk yield and milk energy were increased with tallow, with a simultaneous reduction of milk fat and percentage of protein. Soya bean oil reduced the percentage of milk fat and milk energy produced. The second trial, using similar animals and with similar management had a change-over design in which the concentrate was given alone or with 7% tallow. Results confirmed those of trial 1. The effect of level of feeding on the efficiency of utilization of energy is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)