ANNUAL REPORT, 1942 43 



of experiments but was conducted with single hens, not with groups. The rations 

 and the droppings were analyzed and the balance of manganese calculated. 



One hen on the low-manganese ration retained approximately one half of the 

 total available manganese daily. This suggests that even 21 p. p.m. manganese 

 in the ration was sufficient not only to keep the hen in a positive manganese 

 balance but also to provide a surplus so that it was not necessary to store all the 

 amount available. The hens fed for some months on the high-manganese ration 

 did not store any manganese, and the daily output was almost exactly' the total 

 amount of the daily intake. This means that the hens were in a complete man- 

 ganese balance and that the whole surplus of manganese added to this ration 

 was voided by the hens. 



Manganese and Reproduction of Birds . (Marie S. Gutowska.) Three series 

 of experiments were conducted to observe the effects of different manganese in- 

 takes by poultry on reproduction. In the first series, there was no significant 

 difference in the fertility and hatchabilityofegg5fromhensfedatthelow(17p.p.m.) 

 and the high (61 p. p.m.) manganese rations. In the second series, it was found 

 that the hatchability and fertility of the eggs dropped significantly when the birds 

 were fed a ration containing 14 p. p.m. of manganese; but the differences were not 

 significant in the groups fed the rations containing 17 p. p.m. and 61 p. p.m. of 

 manganese, and the hatchability of eggs in these groups was normal. 



It was concluded that 14 p. p.m. of manganese in a laying ration is a sub- 

 minimum quantity which affects reproduction unfavorably; but 17 p. p.m. is 

 probably not far from the threshold value needed, and 61 p. p.m. is ample. Be- 

 cause normal commercial rations usually contain over 40 p. p.m. of manganese, 

 they do not need, in most cases, to be supplemented with this element. 



In a third series, there was a highh' significant increase in the volume of sperm 

 produced by cocks fed the high-manganese ration as compared with cocks fed the 

 low-manganese ration. The sperm count varied considerably in the two groups 

 of cocks and also in individual cocks on different days. However, no significant 

 difference between the sperm count of the two groups was found. Consequently 

 the increase in the volume of the semen in the group was due not to a change in 

 the density of the sperm but to improved functioning of the testes. 



Effect of Dietary Manganese on the Mineral Content of Some Organs of the 



Hens. (Marie S. Gutowska and Lewis L. Glow, of the Chemistr\- Department 

 cooperating.) An investigation was conducted to determine whether the manga- 

 nese content of the diet would influence the mineral contents of the bones, the 

 livers and the kidneys of the hens. One group received a high-manganese ration 

 (61 p. p.m.); the other, a low-manganese ration (17 p.p.m.). 



The ability of individual hens to store or retain minerals in their bones, liver, 

 and kidneys varied considerabh^; therefore large groups of birds are needed in 

 this kind cf experiment. The ash content of the bones varied more between 

 individuals of the same group than between the averages of the two groups. 



However, the hens on the high-manganese diet had a larger amount of man- 

 ganese in their bones and in their livers than did the hens of the low-manganese 

 diet; but there was no evidence that manganese could be stored in the kidneys. 



The calcium and phosphorus content of the ash of the tibias and sternums of 

 the hens was almost the same for the two groups. 



It was concluded that differences in the manganese content of the diet do not 

 influence the calcium and phosphorus content of the bones and the liver but do 

 influence the amount of manganese in these organs. The amounts of manganese 

 found in the bones and livers, after twelve months on a ration lower in manganese 

 than the average commercial ration for laying hens were considered subnormal. 



