Efficiency of use of metabolisable energy (ME) from fat

The efficiency of conversion of ME to net energy (NE) is not 100% efficient, resulting in loss of energy as heat during mastication of feed and digestion and metabolism of nutrients. However, fat is a very simple nutrient which is not fermented in the rumen and is more efficiently metabolised as a source of energy than other nutrient sources, such that NE value of fats is higher than for other ingredients.

Research work has determined the NE value of Megalac rumen-protected fat to be 27.3 MJ/kg DM based on in vivo studies with dairy cows. This indicates that ME in Megalac is converted to NE with similar efficiency to that generally accepted for utilisation of mobilised body energy in lactating cows (82%). This is substantially above the typical efficiency of energy use of common diets (around 64%), such that heat production associated with digestion and metabolism of Megalac is considerably less than with other dietary ingredients – inefficiencies in energy utilisation result in production of heat.