Forcing the Bird Reduces the Vitality of the Egg.
The reason is this: the bird in its natural condition does not produce her eggs in our climate until April. She will lay twenty-five to thirty eggs, then show a desire to incubate, then will recuperate, and set a second time, perhaps giving a total of thirty-five or forty eggs. Now, we have completely reversed nature in this respect. By judicious feeding, good care, warm quarters, and careful breeding, we have induced the bird to produce her eggs in winter instead of summer, and, not only that, we compel her to lay three or four times as many of them; and when the poor bird shows a desire to incubate and recuperate her exhausted frame, we induce a change of mind, as soon as possible, and set her at it again.
As a natural consequence, as the warm season advances many of the birds are off duty, as it were, and the eggs not only decrease in numbers but in size as well, and during the extreme heat of summer, the later part of July and August especially, the eggs show a decided want of vitality. I never expect, at this season, to realize more than one duckling from two eggs. The same machine full of eggs that would give a hatch of 350 ducklings in the early spring, at this season will not give more than 175 to 200. The eggs appear to be as well fertilized during the first two or three days as in the early spring but evidently there is not vitality enough to carry them through, as the germs soon begin to die, and before the hatch is out you have taken nearly one-half of the eggs away as worthless. Nor is this all.
There is always a far greater mortality among the later hatched birds than in those got out earlier. They are more uneven in appearance, and never attain the size of those hatched earlier in the season,—convincing evidence that the old birds have transmitted their enfeebled, debilitated constitutions through the egg to the young ones. The natural laws of cause and effect are plainly represented here. I have tried repeatedly to overcome this difficulty by changing the feed and quarters of the old birds, dividing their numbers, but without effect. This shows the absolute necessity of selecting large, vigorous breeding stock. This principle applies equally to both land and water fowl.