For wether sheep given 300 g hay and 800 g concentrates the addition of fat (beef tallow:palm kernel oil 9:1) to concentrates at 7 or 12% tended to decrease crude fibre digestibility and increased crude fat digestibility. For 2 rumen-fistulated cows given concentrates containing 7% fat, or 12% fat free or adsorbed on carrier, and 2 cows with fistulae and reentrant duodenal cannulae given concentrates with 12% fat in rations with hay:concentrate 1:2, there were no significant differences between diets in the digestibility of any nutrient; fat digestibility was decreased at feed intakes above maintenance, particularly with the 12% fat concentrates. The use of a carrier in the 12% fat concentrates did not affect nutrient digestibilities for sheep or cows. Inclusion of fat in concentrates increased the metabolizability of sheep diets but there were no significant differences among cattle diets, although methane losses tended to decrease as fat content increased. Additional energy from fat tended to be retained rather than used for milk yield. ME utilization for milk, storage and maintenance was 61-62.5%, tending to be highest with the 12% adsorbed fat. [See DSA 45, 5398 for part I.] (Abstract retrieved from CAB Abstracts by CABI’s permission)

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)