3QO NUTRITION OF FARM ANIMALS 



Interesting data pointing in the same direction are contained 

 in the investigation by Just, in which the nutritive value of 

 non-protein for lambs was compared with that of protein. 

 Estimating the maintenance requirement at 0.5 per thousand 

 and computing the results of the protein periods as in Finger- 

 ling's experiments, it appears that in nearly every case the 

 actual gain of protein was only slightly less than the surplus of 

 digestible crude protein above the maintenance requirement, 

 while in many cases it was distinctly greater than the digestible 

 true protein available. Apparently the non-protein must at 

 least have contributed to the maintenance of the animal if not 

 to its growth, while the utilization of the digestible true protein 

 must have been very high (Table 88). 



Neither Fingerling's nor Just's investigations are adequate 

 to solve the general problem of the maximum possible utiliza- 

 tion of protein in growth, but their results indicate that it may 

 be very high and should lead to caution in the interpretation of 

 experiments upon the protein requirements for growth. 



Utilization of energy net energy values for growth 



472. General conception. The conception of net energy 

 values for growth is entirely analogous to that of net energy 

 values for maintenance or for fattening. They represent that 

 portion of the feed energy supplied in excess of the maintenance 

 requirement which the animal is able to store up in the gain 

 made. It is important to keep this conception clearly in mind 

 when considering the utilization of feed in growth and not to 

 be misled by the greater economic efficiency of the young animal 

 as a producer of live weight increase. 



It is a familiar fact that the young animal gains in weight 

 relatively much faster than when more mature and this has 

 led to the general impression that the young animal utilizes its 

 feed more perfectly than the older animal, or in other words, 

 that the net energy value of a feeding stuff for growth is greater 

 than that for maintenance or for fattening. It is true that the 

 gain in live weight is different in character in the young animal, 

 containing more water and protein and less fat and therefore 

 less energy (458, 459) , but on the other hand the results recorded 

 in i show a greater rate of growth as regards both protein and 



