School of Agriculture (Contribution to the Discussion on the Food Value o f the Egg held at a meeting o f the Food Group, Nutrition Panel, on April 24, 1940) 2'lie cgicieircy of the lieti as a pliysiologicnl niac1iitic.-
The original jungle fowl laid only 20 to 26 eggs n year, but by sclcctivc brccding wc linvc becn able to obtain niucli liiglicr lcvcls of productivity, nnd hcns laying 150 cggs n ycnr nrc now quitc conimon. The lien has thcrcforc bccomc n liiglily spccinlizcd nincliiiic for thc convcrsion of rinv mntcrials into human foodstuffs, and licr cfficicncy in this respect is grcntcr tlinn thnt of any othcr farm animal cxccpt the milch cow. A lien hying 250 cggs a year will inanufncturc and pack 31 lb. of a finished product, though shc hcrsclf inny w i g h only 4 lb. This product mill contain, in addition to vitamins and mincrnls, 4.1 Ib. of protein and 3.3 lb. of fat, whilc tlic pncking consists of about 3 Ib. of cnlcium carljonntc in tlic form of shell. As an cfficicnt producer of onc of our most vnluablc " protective " foods, thc hcn dcscrvcs nn importnnt plncc in our agricultural cconomy a t tlic present timc.
Sizc am1 relatice coniposiliou of the yg.-Eggs vary considcrnbly in sizc, depending in lnrgc iiicasurc on tlic brccd of the hen, thc licnvicr brccds tcndiug to lay the larger cgge. A smnll egg niny wcigli as littlc as 406. ; a large one ns much ns 70 6. An avcrngccl-sized cgg wcighs ti6 g., i.e., approxiiiintcly 2 oz., of aliicli the shcll constitutcs 11%, tlic whitc asyo, and tlic yolk 31%.
Thcse proportions do not w r y to nny grcat cstcnt, no mnttcr what thc siec of egg. Tlic pcrccntngc c o w position of tlic edible portion of the cgg is ns follows :
Whole egg : cdibk portion