| Abstract: | Regression analyses had been made to find interrelationships between the crude fibre content and the EFr content of green feeds. Regression equations were obtained from these analyses which were used to calculate the EFr values, with a sufficient degree of accuracy, from data on the crude fibre content. In these equations the b values were found to be by far more clearly differentiated than in the equations used for calculating digestibility values. These are apparently influenced by the composition of the feeds. The range of variations appears to be only slightly affected when we compare the data with those obtained in calculations made to established the total digestibility values. This is a fact that applies to both the green feeds and their conservation products. Studies investigating the relationships between the content of digestible organic matter (VOS) and EFr (as expressed by the conversion factor (see article) showed that the EFr data could be established, with a fair degree of accuracy, from the VOS values. The f values of the different feeds that were classified into particular groups of feeding-stuffs, were shown to agree fairly well; moreover, they were found to be largely independent of exogenic factors (such as vegetation and N fertilizing). Characteristic differences between the f values of the different conservation products and those of the green feeds were observed although these differences remained within narrow limits (1-3%), so that calculations can be made using only a few factors. When starch equivalents were taken into account it was found that the f values used in calculations for starch equivalents were clearly influenced by feed composition, which, in turn, was influenced by the particular effect of crude values in SE calculations. It is at this point that differences between the two systems of Food Evaluation become particularly apparent. The close relations existing between VOS and EFr values apply, first and foremost, to green feeds and their conservation products. Much wider differences in the f values of different feeds may be observed in the case of foodstuffs having a much more extreme composition. The f values of feedingstuffs with high protein content (e.g. blood meal) may be decreased down to a value of 0.7 while those of foodstuffs rich in fat (e.g. oil cakes or foodstuffs of animal origin containing a high percentage of fat) may be increased up to and over 1.4. In these cases, special circumstances have to be taken into consideration. |
