THE POULTRY INDUSTRY

Wairarapa Times-Age, 14 July 1938, Page 9

THE POULTRY INDUSTRY

EGGS FOR HATCHING. EXPERT ADVICE. The chief Government poultry instructor (Mr C. Cussen) recommends as follows in connection with selecting eggs for hatching:— In selecting eggs for incubation breeders will not go far wrong if they select just that type of egg they would like to market. Avoid the abnormal in size, shape, shell texture and internal quality as revealed by the candling lamp. No abnormal egg should be incubated, for it usually produces an abnormal chick, if it produces one at' all. Well-shaped eggs should be chosen, avoiding long; pointed or round eggs. Eggs of good average size for the breed will give the best results. From 2oz to 2|oz is generally considered ideal. However, allowance must be made for certain strains and breeds which are large egg layers, in which case eggs up to 2|oz should not be rejected. For obvious reasons it is undesirable to incubate eggs below the 2oz standard. It is hardly possible to over-estimate the importance of shell texture. First, it forms a protective covering; secondly, it controls the passage of watervapour and gases of vital importance to the developing embryo; thirdly, the shell plays some part in building up the skeleton of the chick, and, finally, shell texture may be an inherited character. There are, therefore, very good reasons for using only those eggs having strong, smooth shells. A thinshelled egg will either fail to hatch or produce a weakly chicken, arid in any event no poultrykeeper should ever breed from a hen- which does not lay a well-shelled egg. Other defects in shell sufficient serious to justify rejection are hair cracks and mottling. The former can be detected by lightly tapping the egg with a pencil. A cracked shell gives a characteristic dull sound, quite distinct from that of one undamaged. Mottling can be readily seen with the aid of a candling lamp. According to several investigators, this peculiar appearance is due to an uneven distribution of moisture in the shell. It is said that these eggs behave normally when stored, but they do not hatch well. Two conditions which can be detected with the candling lamp, and which are definitely opposed to good hatchability, are blood-spots and watery whites or tremulous air-cells. Eggs having these defects may hatch, though hatchability is low, particularly with watery whites, and as the percentage in the daily collections will be low, it is far wiser to reject them at the outset. Knox and Olson, in studying the effect of tremulous aircells on hatchability, found that both fresh eggs and those stored for three weeks having tremulous aircells gave much lower hatchability than normal eggs for the same age. They showed, further, that jarring eggs with the large end downward readily produced tremulous aircells, while jarring the other way up did not do so. Jarring did not affect hatchability unless it caused tremulous aircells. It is, therefore, inadvisable to keep hatching eggs with the broad end down. They should be stored on their sides or with the broad end up, and if transported should be packed with the broad end up and in such a manner as to reduce jarring to the very minimum.