41 6 Journal of Agricultural Research voi. iv, no.s 



RELATIVE NUTRITIVE VALUE OP THE FEEDS 



The following calculations show the method employed in estimating 

 the relative nutritive values. To obtain the number of pounds of feed 

 required to produce one pound of fat, the total number of pounds of feed 

 was divided by the total fat production. The quantity of prickly-pear 

 used to replace the hay or other feed was considered equal in value 

 for fat production to the amount of feed which it replaced. The same 

 method was followed in estimating the relative values of the different 

 feeds on the bases of nutrients digested and energy values. The results 

 are given in Table VII. 



Table VIII contains different methods for comparing the relative nutri- 

 tive value of the feeds tested, estimated from their chemical composition 

 and digestibility. If the digestible nutrients or therms furnished an 

 accurate means of estimating the relative values of different kinds of 

 feeds, I pound of digestible nutrients or i therm in one kind of feed would 

 be equivalent in producing power to i pound of digestible nutrients or i 

 therm in another kind of feed. Thus, while 1.40 pounds of digestible 

 nutrients in prickly-pear are equivalent to i pound of digestible nutri- 

 ents in sorghum hay, o.go of a pound in the prickly-pear is equal to i 

 pound in the cottonseed hulls, and while 1.61 therms in the prickly-pear 

 are equal to i therm in the hay, 3.03 therms are required to equal i therm 

 in cottonseed hulls. The digestible-nutrients method shows less variation 

 than the energy-value method and for this reason is more accurate, in 

 this investigation at least, but both show such wide variations as to make 

 them of doubtful value in estimating the nutritive values. 



On account of the variation in the water content of prickly-pear and 

 sorghum hay, it was thought best to reduce them all to a dry-matter 

 content that would be near the average for the particular feed. The 

 relative values were estimated by using the following percentages of 

 dry matter for the various feeds: Prickly-pear, 10 per cent; sorghum 

 hay, 80 per cent; cottonseed hulls, 90 per cent; silage, 25 per cent. 

 Calculated in this way, the relative values on the basis of feed consumed 

 are as follows : 



Medium prickly-pear and sorghum 

 hay versus heavy prickly-pear 



and sorghum hay i pound of sorghum hay equals 15.9 



pounds of prickly-pear: 

 Medium rations of prickly-pear 



versus sorghum hay i pound of sorghum hay equals 10. i 



poTUids of prickly-pear. 

 Medium rations of prickly-pear 



versus sorghum silage i pound of sorghum silage equals 2.6 



pounds of prickly-pear. 

 Medium rations of prickly-pear 



versus cottonseed hulls i pound of cottonseed hulls equals 



5.8 pounds of prickly-pear. 



