872 EXPERIMENT STATION EECORD. 



weight indicates tliat wliile growth was stunted on the first ration the cliickens 

 still possessed the power to grow rapidly on the ration of lot 1. The difference 

 in the nutrition in these two lots of chicks is deemed due, in all probability, to 

 the difference in the amount of lysin received by the two lots, and possibly 

 to a difference in the quantity and nature of the fats contained in the two 

 rations. The mash fed to the chicks of lot 1 contained 13.08 per cent of fat, 

 and the dry grain mixture 8.21 per cent, whereas the mash fed to the chicks 

 of lot 2 contained only 1.8 per cent of fat and the grain mixture 1 per cent. 



In order to determine to what extent the difference shown by the two 

 lots was due to difference in the protein or fats two lots of chicks were fed for 

 GO days the same rations as in the foregoing experiment except that to the 

 ration supplied to lot 2 there was added sufficient butter fat to bring the 

 fat content up to that of the ration fed to lot 1. The chickens of lot 1 showed 

 an average gain per chick of 277.3 gm. over the chickens of lot 2. The differ- 

 ences shown by these two lots of chicks at the end of the feeding period were 

 very striking. The chickens of lot 1 were strong, growthy, and perfectly 

 feathered in contrast to the chicks of lot 2, which, although in perfect health, 

 were markedly stunted in their growth and showed the feathering character- 

 istics of a much younger chick and the yellow color and appearance of the 

 newly-hatched chick about the head and neck. The external sexual character- 

 istics of these two lots also showed most striking differences. In lot 1 the 

 cockerels were easily distinguished from the hens and both showed well- 

 developed, highly colored gills and combs, whereas tlie chicks of lot 2 showed 

 no well-developed external sexual characteristics whatever, the combs of both 

 sexes being rudimentary and colorless. 



These two lots were reversed, as in the first experiment, and the average 

 percentage gains of lot 1 were 5.1 against 28.9 for lot 2. Withiu one week 

 after reversing the rations fed to lots 1 and 2 the external sexual character- 

 istics of the chicks of lot 2 became noticeable, and at the end of three weeks 

 were very pronounced. 



It is deemed evident from these results that the marked differences sht-wn 

 by these two lots of chicks in the rate of growth and development can not 

 be ascribed to the fat content of the two rations, but rather to differences in 

 the amino-acid content of the two rations and in all probability to differences 

 in the lysin content. 



When to feed the baby chick, B. F. Kax.tp (North Carolina Sta. Bui. 235 

 (1916), pp. 13-1.5, figs. 7). — Studies were made to determine how much of the 

 abdominal yolk was absorbed in the embryonic stage in the shell, or in other 

 words, to determine how much food was left in the abdominal yolk at hatching. 



The weights were taken of 1,4.54 White Leghorn eggs, the average being 57.7 

 gm. By boiling the egg and weighing it was found that the average weight 

 of 10 yolks was 17.78 gm. In a study of ten baliy chicks that had started to 

 pip out of the shell but had died, it was found that the unabsorbed yolk 

 weighed, on an average, 8.5 gm., or 47 per cent unabsorbeil. Tliere appeared- 

 to be no constant definite weight of the amount of yolk left in the yolk sac 

 unabsorbed at this period of the chick's life. The weights varied from 8 to 

 10 gm., and it was found that the rate of absorption of the yolk varied in dif- 

 ferent individuals. 



Forty chicks were killed by the aid of chloroform at different ages, skinned, 

 and the carcasses immediately placed in a 10 per cent solution of formaldehyde. 

 Later these carcasses were sectioned longitudinally for the purpose of making 

 a study of the relation of visceral organs with respect to the abdominal 

 yolk sac. 



