Storey's Guide to Raising Chickens (68 page)

Insufficient

Nutritionally deficient

The main cause of poorly balanced rations is feeding breeders too much scratch grain or other treats. To ensure the proper protein/carbohydrate balance, reduce your flock’s grain ration about a month before the hatching season begins.

See that your breeders get enough to eat for their size, their level of activity, and the time of year. Feed either free choice or often so those lowest on the totem pole will get a turn at the hopper. Examine each bag of feed to make sure it isn’t dusty, moldy, or otherwise unpalatable, which will cause your chickens to eat less.

Periodically weigh a sampling of both cocks and hens — a weight loss of more than 10 percent can affect reproduction. Underfed cocks produce less semen; underfed hens don’t lay well.

A hen’s diet affects the number and vitality of her chicks and the quality of carryover nutrients the chicks continue to absorb for several weeks after they hatch. Nutritional deficiencies that may not produce symptoms in a hen can still be passed on to her chicks. Feeding the breeder hen therefore includes feeding her not-yet-hatched chicks.

The same ration that promotes good egg production won’t necessarily provide embryos and newly hatched chicks with all the elements they need to thrive.
Layer ration
contains little animal protein and too few vitamins and minerals for proper hatching-egg composition and high hatchability. Feeding lay ration to a breeder hen may result in a poor hatch or nutritional deficiencies in her offspring. The older the hen, the worse the problem becomes.

To improve your hatching success, feed your flock a bona fide
breeder ration
, rich in necessary nutrients, starting 2 to 4 weeks before you intend to begin hatching. If you’re lucky, you’ll find breeder ration at your feed store. Be sure it’s fresh, and use it within 2 weeks after it was mixed. Even if you feed your flock the best breeder ration in the world, nutritional deficiencies will result if the feed is stored so long that the fat-soluble vitamins are destroyed by oxidation.

If you can’t find a ready source of breeder ration at your feed store, the closest alternative may be a game-bird ration. If neither is available, 6 weeks before you begin collecting hatching eggs, supplement rations with animal protein as you would for molting (see
page 199
) and add a vitamin/mineral supplement to the drinking water.

Excessive embryo deaths during mid and late hatch may be a sign of low vitamin levels in the breeder ration. If you have reason to question the freshness of the ration you use, feed your flock natural supplements or add vitamins to their drinking water prior to and during the breeding season.

Vitamin A
is essential for good hatchability and chick viability. It comes from green feeds, yellow corn, and cod liver oil. If you use cod liver oil, keep it fresh by mixing it into rations at each feeding.

Vitamin D
is related to the assimilation of calcium and phosphorus needed for egg production. Deficiency causes shells to become thin. Since an embryo takes calcium from the shell, thin-shelled eggs may produce stunted chicks. Two signs of deficiency are a peak in embryo deaths during the nineteenth day of hatch and chicks with rickets. Vitamin D can be supplied by cod liver oil and sunlight.

Vitamin E
affects both fertility and hatchability. It comes from wheat germ oil, whole grains, and many fresh greens.

Riboflavin,
one of the B vitamins, is often deficient in poultry rations, resulting in embryo deaths in early or mid incubation, depending on the degree of deficiency. Chicks that do hatch may have curled toes and may grow slowly. Riboflavin comes from leafy greens, milk products, liver, and yeast.

Calcium deficiency
can cause thin-shelled eggs and reduced laying. Calcium excess can reduce hatchability. Supplying a calcium supplement free choice rather than mixing it into rations allows for differences in the needs of individual hens.

For fast results, use aragonite (calcium carbonate) or agricultural limestone (calcitic limestone, which is mostly calcium carbonate), not dolomitic limestone (which contains a higher percentage of magnesium carbonate), as the latter is detrimental to egg production and hatchability. Crushed oyster shell is a good long-term supplement.

The touchy problem of providing breeders with adequate nutrition will be compounded if you hatch early in the season, before your hens have access to fresh greens. If you live in a northern area, you can measurably improve your hatching success by supplementing with sprouted grains, or alfalfa meal or pellets, or by delaying incubation until your birds have access to fresh forage and plenty of sunlight.

When a cock mates with a hen, sperm travel quickly up the oviduct to fertilize a developing yolk. If the hen laid an egg shortly before, the mating will likely fertilize her next egg. The number of additional eggs that will be fertilized by the mating varies with the hen’s productivity and breed. Highly productive hens generally remain fertile longer than hens that lay at a slower rate, and single-comb breeds remain fertile longer than rose-comb breeds — possibly as long as a month, but that’s pushing your luck. The average duration of fertility is about 10 days.

However, if you switch cocks, the eggs laid after making the switch are more likely (but not guaranteed) to be fertilized by the new cock than by the old one.
To be reasonably certain eggs are fertilized by the new mating, wait at least 2 weeks before collecting them for hatching.

MALE/FEMALE MATING RATIOS

Although an egg must be fertilized to hatch, not all fertilized eggs do hatch. Eggs fail to hatch for a variety of reasons, not all of them easy to determine. One possible reason is that the embryo died before incubation began. This phenomenon, commonly known as
weak fertility
, may have nothing to do with fertility at all but may be due to other deficiencies within the egg.

Like all reproductive qualities, fertility has low heritability. Aside from problems related to inbreeding depression, management factors (rather than inheritance) are more likely to play a significant role. The many possible reasons for low fertility include the following:

The flock is too closely confined.

The weather is too warm.

Breeders (both cocks and hens) get fewer than 14 daylight hours.

The cock has an injured foot or leg.

Breeders are infested with internal or external parasites.