POULTRY 1003 



was also given a weighed quantit}' of gravel, in portions renewed as and when 

 the birds consumed the contents of their trough, so that during the entire 

 experiment each chicken of group I swallowed about 600 grams of gravel. 

 The weight of the gravel varied from 0.14 to 0.24 gr. per grain ; the width 

 from 1.2 to 7 mm. and the length from i to 10.5 mm. To get rid of soluble 

 parts the gravel was first scorched in a flame, then, before administration, 

 was boiled in dilute hydrochloric acid, and afterwards in water. The 

 average daily ration given per individual was almost equal in both 

 groups: in group I, each subject consumed 73.4 gr. of maize, and in group II, 

 72.4 g. In the course of the experiments the chickens were often weighed 

 {the results are indicated in 2 tables). In both groups there were birds whose 

 weight increased during the 2 14 nionths of experiment, and others whose 

 weight diminished. The latter were the majority', so that at the end of the 

 experiment the weight of the birds of the ist group showed a reduction of 

 314 grams (averaging 52.3 per individual), and that of the 6 birds of group 

 II a reduction of 597 gr. (99.5 gr. average per individual). 



Allowing for the daily ration of group II, which was i gram less, it 

 may be concluded from the above results that the 2 groups assimilated their 

 food in an equal degree, so that from the point of view of grain utilisation it 

 is quite immaterial whether it is administed with or without gravel. In the 

 average change of live weight there was a very small difference between 

 the 2 groups, and it was concluded that the live weight of the birds fed 

 with maize with or without gravel varied uniformly. 



At the end of the experiment, the gizzards of the birds of each of the 

 2 groups were examined, and gravel was found which was carefully clean- 

 ed and then weighed. The gizzards of the birds of group I contained on 

 the average 13 grams of such gravel, while in those of group II there was 

 an average of 6 gr. As however the chickens of group IT received no gravel 

 during the test, it is evident that they kept it in the gizzard for about 2 14 

 months, which suggests that they use it for grinding the grain swallowed, 

 and that the anatomical construction of the gizzard is .such as to render the 

 expulsion of the gravel difficult. (Re;aumur had already recognised the 

 necessity for the presence of gravel in the gizzard of graminivorous birds). 



The 2 757 grains of gravel found in group I weighed together 52.7 gr. 

 (0.019 &^- per grain); in group IT, bbj grains weighed together 29.5 gr. (0.44 

 gr. per grain), which shows that the birds of group II kept bigger grains of 

 gravel. There were also differences in the shape of the gravel ; that of 

 group II was rounder and smoother, which must be attributed to the conti- 

 nuous friction in the gizzard. Finally, the grains of gravel weighing 13 

 grams found in group I prove that the greater part of the gravel was eva- 

 cuated with the excrement, as the birds of this group had still received 60 

 grams of gravel on the average, 10 days before being killed. 



It follows from these observations that gravel may be dispensed with 

 during the short period of fattening of chickens (intensive fattening lasts 

 15 days at most), because in the gizzard of poultry there is always the 

 necessary quantity of gravel for grinding the grain. It still remains to be as- 

 certained, however, whether digestion takes place perfectly in case of com- 



