A study of growth in calves III. Energy and nitrogen efficiencies of growth of carcass tissues

The gross energy and nitrogen contents of muscle, fat, and connective tissue of calves were determined, and from these data and feed analyses the gross energetic (GEE) and nitrogen efficiency (GNE) of growth, and the gross efficiencies of accretion since birth (GEA, GNA) were calculated. The percentage range of actual efficiency values for calves were GEE 55.3-7.7, GEA 18.1-1.4, GNE 58.1-22.8, and GNA 28.1-7.3. Within each treatment group these values were higher in the heavier calves. An hypothesis for the apparent temporary rise in these values in the heavier calves is that a compensatory mechanism acts in calves on low energy and possibly low N intake to enable them better to utilize their food. The results were obtained in calves whose diet was comprised of a reconstituted milk of low-solid content which led to low growth rates