356 POULTRY PRODUCTION 



PaA'iic,' Ii(i\ve\er, notes tliiit when salt was iiscil iiitcr- 

 (■lia,nn'('al)l>' in four dift'crcnt inashes it did not a])])i'ar to 

 iiillucni'c llu'ir ]>;il.'ital)ilit>' as indicated ]>\ the relati\e 

 a.inouiils (•oii^iiincd. 



Shell {Oyster). — Tlic necessity of a sui)pl\' of lime or calcium 

 for the formation of cKij shells is shown hy ^Vieke (as reported 

 l>y II. .]. ^VIleeler-) in the followinji; analysis of e^^g shells: 



Per cent. 

 Caiijon:itc of lime ....... .93.71 



Carbonate of majjriesia .... ... 1.39 



Phosphate of Hmc ........ 0.76 



Organic substance . . .... . 4.24 



AV. P. Wheeler' found that where oyster shell was the only 

 mineral feed given hens, aside from tliat contained in the 

 grains, in one case 84 per cent, and in another over 88 per 

 cent of the lime of the egg shell was tuiaccounted for by 

 any feed given aside from the oyster shell. When broken 

 glass was substituted for the oyster shell, fewer eggs were laid 

 and the shells were thinner. 



CanP has shown that the correlation between the mmd)er 

 of eggs liiid and the amount of oyster shell consumed is \'ery 

 high i.N7L'f ± .IKIT'.I). Tliat is to say, the consumption of 

 shell iiicreascil or decrciiscd directly as egg ]>roduction in- 

 eiX'ased or decreascil. 



Oyster shell contains 95 per cent carbonate i)f lime. One 

 poimd of oyster shell contains lime enough for the shells of 

 sc\'en to eight do/.cn eggs. Like grit, shell should be fed in 

 sizes to suit tlie size of the ^toc'k. ( 'lam sliell is not so highly 

 esteemed b\' ])o\dtryiiien as oyster shell. Hart an<l Iial])in-'' 

 foimd that when the exact calcium t'(iTU\alent was furnished 

 from o} stt'r shell and chini shell the former was considerably 

 more elhcicut for egg jiroduction, iiiid both were superior 

 to lime roc]<, calcnun carbonate and bone. 



I .[.iUr. .\)ii. .\s-ii Iii-I. an. I ln\r,l. in I'muI Mu-I.. \>,\. ili, Xc. ,3. 



- Rhode Ishand Bulletin No. S4. 



■' Twenty-sixth Annual Report, New York I'^.xpcriment Station. 



< .Jonr ,\ni, ,\ssn. InsI and ln\.-st. in \\,m\ lln-l.., vol li, N(.. 0. 



6 Wis.'onsin lluUrtin No. 31!). 



