FERTILITY

Evening Post, Volume CXIX, Issue 104, 4 May 1935, Page 32

FERTILITY

Heavy breed hatching eggs are liable to prove rather disappointing early in ♦he season. At the best of times the percentage of infertile eggs ranges from 15 per cent, to 30 per cent., and with inclement weather and short days due

allowance must be made for a higher percentage of infertile eggs. White Leghorng give a better hatchability than the dual purpose breeds, since they are far more active.

It is very seldom that a male bird proves incapable of fertilising es?gs. and if the fertility is below normal a careful inspection of all the breeding birds should be made. Over-fatness and body lice will often lower fertility, but above all unlimited free range in sheltered yards will give the best results. Aged male birds should not be used in the breeding pens until their health is fully recovered after the natural moulting period. If crossbreds are used, then the male should be of a light breed and the females of a dual I purpose breed, not vice versa.

Good hatchability is affected by other points than the actual management of the incubator. Extremely low or high temperatures will lower the hatching power of eggs in that the quality of the , eggs is lowered before they are set for , incubation. As a general rule high egg producing hens give better hatchability than low producers, and pullet eggs will nearly always hatch better than hen eggs. This does not imply that it is advisable to incubate pullet | eggs, as the practice of breeding from pullets cannot be too keenly condemned. Extra large eggs do not a? a rule hatch as well as standard-sized eggs, whilst any eggs held more than ten days before incubation definitely show poorer hatchability than fresh eggs. 7?he first chicks hatched are usually the strongest in a clutch, whilst the last to hatch usually have a higher mortality rate. Shell texture quality does not appear to affect hatchability, but it is most desirable that only wellshelled eggs be used ■ for incubation purposes, as it has definitely been shown that this characteristic is hereditary. Those eggs with ridges, and those of abnormal shape, should never be used for hatching purposes.

One of the best ways of sorting out undesirable "eggers" is to use trapnests on the breeding pens for a fortnight. Unless it is intended to continue

trapping there is no need to identify every bird, but when a hen lavs an inferior egg she should be rung with a coloured leg band and as soon as she wears three of these rings she should be culled out as an undesirable breeder. Working along these lines almost every egg collected from a special mating will then be fit for incubation, thus getting the maximum use out of a special male bird.

If it is necessary to hold eggs for

more than a few days before incubation they should be kept out of a current of air and turned twice daily. One of the best ways to keep a few is to place them on a tray of bran and cover them with a sack; more should be packed in an egg crate and the whole crate tipped up each day so as to turn all the eggs at once. If possible incubate stale eggs in one machine and

fresh eggs in another, as it has been

proved that stale eggs take from twelve to thirty-six hours longer to

hatch than very fresh eggs. There is little evidence to show that the mixing

of brown-shelled eggs with white eggs gives lower hatchability, though many poultrymen prefer to incubate them separately.