191C] ANIMAL PRODUCTION. 561 



pp. 51-129. pis. 2, figs. 3).— In this report the work of other investigators on the 

 subject is briefly reviewed, and a short summary of the present-day linowledge 

 of the chemical constituents of the nervous system is given. The analytical 

 methods employed are described in detail. A comparison of the chemical 

 analysis of the central nervous system in five cases of uncomplicated pellagra, 

 as compared with the chemical analysis of normal controls, showed that in 

 pellagra the central nervous system is subject to a series of chemical changes 

 involving, principally, certain lipoids. 



ANIMAL PRODUCTION. 



The production coeflacients of feeds, G. S. Feaps (Texas Sta. Bui. 185 

 (1916), pp. 5-16). — It is stated that the value of a feeding stuff consists in its 

 volume, which satisfies the appetite of the animal, its digestible protein, which 

 furnishes material for muscular and other similar tissue, and its productive 

 value, which represents its value for the purpose of supplying energy for work, 

 or bodily activities, heat, or material for the production of fat, etc. This bulle- 

 tin describes a method of calculating the productive values of feeds from their 

 chemical composition. 



The productive value of a feed is defined as the amount of fat that the 

 feed will produce upon a fattening animal, when it is fed in addition to a 

 basal ration already sufficient for the bodily needs of the animal. The author 

 prefers to express the productive value in terms of fat for the reason that it 

 represents as nearly as is possible the exact substance measured in the ex- 

 periments, and does not involve any assumption as to the quantity of produc- 

 tive energy consumed in forming fat, or other similar assumptions. Knowing 

 the composition and coefficients of digestibility the productive value in terms 

 of fat of a given feeding stuff may be calculated, but in order to simplify tlie 

 calculation it is proposed to use a factor to be known as the production coefli- 

 cient. This is defined as the factor which, multiplied by the percentage of 

 the nutrient, gives the productive value of that nutrient in terms of fat. 



As the production coefficient is calculated from the coefficient of digestibility, 

 anything that will affect the digestion will also affect the production coeflBcient. 

 Also, some feeds may be regarded as mixtures of two or more constituents 

 which have diff'erent coefficients of digestibility and different production values. 

 Cotton-seed meal, for example, may be considered as composed of cotton-seed 

 kernel residue and cotton-seed hulls, and the amount of cotton-seed hulls may 

 be calculated from the amount of crude fiber present. Since cotton-seed kernels 

 and cotton-seed hulls have different production coefficients, the quantity of 

 crude fiber will thus affect the production coefficient of the feeding stuff. 



There are similar variations in the composition of other feeding stuffs which 

 are related to different constituents having different digestive coefficients and 

 different productive values. These are problems which are under study. 



A table is given which shows the production coefficients of a number of feeds, 

 based upon the average coefficients of digestibility. A column is included which 

 shows the method of correction used for the crude fiber, or nitrogen-free ex- 

 tract, or both, as the case may be. 



[Feeding stuffs], F. A. Clowes (Hawaii Sta. Rpt. 1915, pp. 51-53). — 

 Honohono (Commelina nudiflora) is described as an extremely succulent feed, 

 much relished by cattle. Cattle fatten and produce an abundance of milk when 

 pastured where it is plentiful. The total yield of green feed per acre, cal- 

 culated from an experimental plat 10 ft. square, was 223.G tons. Per acre pro- 

 duction it compares very favorably with green alfalfa both in protein and in 

 other food constituents. 



