r 



1917] ANIMAL PRODUCTION. 65 



calcium balance. No effect was produced on the calcium output by the addi- 

 tion of sodium bicarbonate to either of these diets. The addition of hydrochloric 

 acid to the raeat-craclier diet produced a prompt increase in the excretion of 

 calcium by way of the kidneys, and the addition of the acid to the dried-sklm- 

 milk diet produced an increased urinary excretion of calcium, thoiigh not at the 

 expense of the fecal output. 



The active constituent of the thyroid: Its isolation, chemical properties, 

 and physiological action, E. C. Kendall (Jour. Biol. Chem.., 29 {1917), No. 2, 

 pp. XXIX, XXX). — The active constituent separates in microscopic needles. 

 It may be precipitated as free base or in salt form. Its chemical properties 

 depend upon the degree of purification and the presence of other substances, 

 and its physiological activity depends upon the amount administered and the 

 susceptibility of the individual. 



The use of pancreatic vitamin in cases of malnutrition, W. H. Eddy (Jour. 

 Biol. Chem., 29 (1917), No. 2, pp. XVI, XVII).— A report of a preliminary study 

 which suggests the possibility of stimulating assimilation by the artificial feed- 

 lug of pancreatic vitamins. 



ANIMAL PRODUCTION. 



The associative digestibility of com silage and cottonseed meal in steer 

 rations, II, P. V. Ewing, C. A. Wells, and F. H. Smith (Georgia Sta. Bui. 125 

 (1917), pp. 1.^9-164, fig. 1). — This is the second progress report of an investi- 

 gation at the station on the associative action of feeds, or the influence of one 

 ingredient of a ration on the digestibility of the nutrients of the other ingredient 

 (E. S. R., 34, p. 169). The feeds used were silage made from corn from which 

 the ears had been removed, and screened choice cottonseed meal. Of the six 

 rations involved in the experiments two were silage alone, two silage and cot- 

 tonseed meal, and two cottonseed meal alone. Only one of the two rations 

 of cottonseed meal gave satisfactory digestive trials. High-grade two-year-old 

 Shorthorn steers were used. 



In the digestive trials, which lasted ten days each, the feces composite only 

 were collected. An improved form of feces duct, which is described, was used. 

 The feces sample was divided into three fractional parts by a method which 

 is described, one fraction being assumed to represent the corn silage residue. 

 Data are tabulated showing the feed schedule, analyses of feeds used, a general 

 summary of the digestion trials, analyses of the different fractional parts of 

 the feces, the utilization of the nutrients consumed, and gains and losses in 

 digestibility due to food combination. 



In general, it was found that with the feeds used there were no appreciable 

 differences in the digestibilities of the nitrogen and fats as a result of the com- 

 bination of the two feeds. When silage and cottonseed meal were fed together 

 in the proportion of 3.4:1, the digestibility of the total dry matter was 4.62 

 per cent below the theoretical standard ; and when these feeds were combined 

 in the proportion of 7.7 : 1 the digestibility of the total dry matter exceeded 

 the theoretical standard by 1.1 per cent. There was an appreciable gain in di- 

 gestibility of the ash and nitrogen-free extract in both rations in which the 

 feeds were combined, but an appreciable loss in the digestibility of crude fiber. 

 In attempting to ascertain the cause of these gains and losses of digestibility 

 by an examination of the fractions of the feces, it was concluded that a steer 

 macerates his food approximately four times as well when fed silage alone as 

 when fed silage and cottonseed meal in the proportion of 3.4 : 1, and twice as 

 well when fed silage alone as when fed the mixture in the proportion of 

 7.7 : 1. The digestibility of the dry matter and crude fiber of silage seemed 



