296 FEEDING EXPEEIMENTS 



of ambiguity, however, has always enveloped this ratio, some writers 

 considering " crude protein," i.e., total nitrogen x 6*25, others being 

 careful to restrict the term albuminoid to the true proteids present. 



From a careful study of all the published accounts of feeding ex- 

 periments conducted in Britain with cattle and sheep 1 the author 

 found that there was little correlation between the true albuminoid 

 ratios of the food supplied and the average gain in live weight and 

 came to the conclusion that too much importance has been attached 

 to this ratio. Provided the animals received sufficient proteid to meet 

 their requirements, the gain in live weight then depended mainly 

 upon the amount of digestible non-albuminoids they consumed. 



The writer deduced from a consideration of the results that for 

 cattle of over 900 Ib. live weight, a daily supply of TO to 1'2 Ib. of 

 digestible proteid (i.e., real albuminoids) per 1000 Ib. live weight was 

 sufficient for the animals' requirements and that the average daily gain 

 in live weight per 1000 Ib., then depended mainly upon the supply of 

 non-albuminoids. Expressing these in starch equivalent, about 15 or 

 16 Ib per 1000 Ib. live weight, per day, seemed to be capable of 

 yielding about the maximum daily average gain 1-8 Ib. per 1000 Ib. 

 per day. These figures were derived from results obtained with about 

 750 animals. 



With sheep, the results obtained with over 2000 animals led to the 

 conclusion that about 1-75 Ib. digestible real albuminoids per day per 

 1000 Ib. live weight was the most suitable amount, while for non- 

 albuminoids expressed as starch, about 18 Ib. per 1000 Ib. per day gave 

 the maximum average daily gain in live weight, viz., about 3 Ib. per 

 1000 Ib. This applies to adult sheep of live weight of 100 Ib. or 

 upwards. 



Experiments with animals are subject to many disturbing circum- 

 stances and even where every care has been taken, contradictory results 

 are often obtained when the experiments are repeated. The effects of 

 accidental differences, individual peculiarities of the animals used, and 

 other circumstances difficult or impossible to control, are often very 

 great and sometimes entirely overshadow and conceal those of the 

 nature of the feeding which the experiment was designed to determine. 

 The larger the number of animals used in the experiment, other things 

 being equal, the greater is the reliance that can be placed upon the 

 results. Though the experiments reviewed by the writer in the papers 

 just cited, were directed to very diverse objects, it is probable that the 

 general principles deducible from the results are freer from the dis- 

 turbing influences of individual peculiarities of the animals, than any 

 single experiment could be. 



Fig. 8 shows the averages of the daily supply of real albuminoids 

 per 1000 Ib. live weight, plotted against daily increase in live weight 

 per 1000 Ib., with cattle exceeding 900 Ib. live weight. Each small 

 black column at the base of the diagram indicates, by its height, the 

 number of animals which received per day an amount of real al- 

 buminoids intermediate between the quantities represented by the 



1 Vide Trans. High, and Agric. Soc., Scotland, 1909, 196 ; 1910, 168 and 178. 



