Search

Data for individual feed intake, liveweight, and egg production were recorded for five genetically different groups of 40 pullets each during 10 test periods of 28-days each. Average ambient temperature at cage level varied from 6.7 C during January to 21.1 C during June. A 2890 kcal/kg metabolizable energy (ME) diet with 16% crude protein (CP) was fed ad lib. Average egg production for the Small Leghorns (SL) was about 60%, for white-egg hybrids (WL) about 75%, for brown-egg hybrids (BL) about 72%, for female line broiler breeders (BB) about 48%, and for broiler-cross pullets (B) about 51%. Average grams liveweight and grams feed intake per hen day were: SL, 1426 and 83.7; WL, 1809 and 104.9; BL, 2610 and 122.9: BB, 4197 and 156.2; and B, 4158 and 167.7. Partition equations which describe the data for SL, WL, BL, and BB, assuming 70% efficiency of use of feed ME for maintenance, tissue formation, and egg formation were: F = (.534 − .004T)W .653 + 2.76ΔW + .80EM and F = (.259 −.00259T)W.75 + 2.76ΔW + .80EM. Similar equations for B, assuming 65% efficiency use of ME, are: F = (.589 − .0044T)W.653 + 2.9ΔW + .85EM and F = (.275 − .00275T)W.75 + 2.9ΔW + .85EM. The terms are: F = grams feed/hen day; T = ambient temperature in °C; W = grams liveweight; ΔW = grams daily change in liveweight; EM = grams egg mass per hen day. Equations which assume 70% efficiency of use of ME are shown to predict feed intake of a diet containing 2890 kcal of apparent ME per kilogram for white and brown-egg layers and broiler-breeder pullets varying in individual body weights from about 1 to 5 kg. Equations, assuming 65% energetic efficiency, describe feed intake for a group of broiler-cross pullets.

INTRODUCTION BROODINESS has been greatly reduced in all strains of chickens bred for egg production. There is general agreement that elimination of this inherited trait is one of the quickest and surest steps in increasing annual production. Hays and Sanborn (1928) reported that during the pullet year relatively fewer Rhode Island Reds broody before July 1 died after that date than birds not broody before July 1. Further evidence that the elimination of this natural phase of the reproductive cycle may result in decreased vigor was presented by Hogsett (1941). He reported that among his 1939 flock of 1,896 pullets, 105 were broody one or more times during their first laying year. Survival through the first laying year among these broody pullets was 87.6 percent while survival among the 1,791 nonbroody pullets was 74.2 percent. Now it may be reasoned that some of the so-called nonbroody pullets which died would . . .

Summary and ConclusionsAbnormal embryos and chicks, with relatively short bones, were frequently produced in eggs laid by birds which received diets lacking in some factor or factors present in wheat germ, liver, and whey. The activity, amount or utilization of this factor or these factors was augmented by permitting the birds access to direct sunlight and green range.

IN A PREVIOUS paper (Byerly and Quinn, 1936) it was shown that 47.5 percent of 1,102 Rhode Island Red chicks hatched at the National Agricultural Research Center, Beltsville, Maryland, carried black spotting on the head or black striping on either head or body, also that 42.1 percent of 663 chicks from an excellent standard bred flock carried spotting or striping, indicating that these characteristics may be rather widely distributed among Rhode Island Red flocks. It was further shown that 84.9 percent of the striped or spotted Beltsville chicks were females, whereas 77.8 percent of the non-spotted, non-striped chicks were males. Several breeders and hatcherymen have questioned the extent of the distribution of the characteristics mentioned above. They have also pointed out that little melanic pigment (black spotting and striping) appears in the Rhode Island Red Chicks shown in commercial and standard bred exhibition classes. It was the opinion of the . . .

ALTHOUGH many phases of the calcium metabolism of the chicken have been studied, very little attention has been given to the effect of the calcium and phosphorus content of the diet of laying pullets and hens on the production and hatchability of eggs. The purpose of this paper is to present data on this phase of the calcium and phosphorus metabolism of the chicken. These data demonstrate the deleterious effect, hitherto unsuspected, of a high level of calcium intake of laying chickens on the ability of their eggs to hatch, and they suggest that in practical poultry husbandry it is very desirable to control the calcium intake of laying chickens. LITERATURE Wheeler (1919) made many inorganic analyses of the shells of eggs and of the carcasses of chickens and ducks that had received calcium, magnesium, and strontium from several sources as supplements to their diet. He found that the diets . . .

THE data presented by Byerly and Olsen (1931) indicated that from 2 to 3.5 percent of all fertile eggs incubated contain at hatching time dead chicks with their heads in the small instead of the large end of the shell. In order to save the poultry industry the very large sums lost through this means, it is necessary to know the causes for this malposition and the portion of the incubation period during which those causes act. Byerly and Olsen (loc cit.) demonstrated that gravity is a very important factor in determining the hatching position of the chick embryo. The present experiments were designed to give information about the time of determination of the malposition head-in-small-end-of-egg and the mechanism of its determination. Data have been gathered coincidentally on the lethality of this malposition. MATERIAL AND METHOD Several lots of eggs were incubated for various periods in some one of the . . .

POULTRYMEN have long recognized that egg production can be increased during the fall and winter months by artificially lengthening the daily light period. Whetham (1933) correlated the seasonal rates of egg production of hens kept in latitudes throughout the world with the seasonal variations in length of daylight for these same latitudes. It was concluded that the light supply is an important factor in the seasonal distribution of egg production. It is only within recent years that the factors responsible for the striking physiological effect of increased light have been subjected to experimental investigation. It has been quite convincingly established that light stimulates the anterior pituitary gland which in turn releases the hormones necessary for gonadal development and functions. The extensive literature pertaining to this subject has been reviewed by Rowan (1938) and Bissonnette (1936). Penquite and Thompson (1933) reported the use of continuous lights on Leghorns and emphasized the . . .

Sanctuary, (1925), Hutt (1929), Smith (1930), Hale (1930), and Byerly (1930), have reported and discussed data on malposition in the chick embryo, but no experimental work on the cause of malposition has come to the author’s attention. The present paper is presented as a contribution to the solution of the causes of malposition and to our knowledge of its importance as a factor in hatchability. During the earlier portion of the incubation period the embryo floats freely on the upper surface of the yolk. As incubation proceeds, the embryo turns to a new position relative to the overlying shell whenever the egg is turned. If the egg stands on end, this statement must be somewhat qualified because the ehalazae prevent the embryo from reaching the middle of the upper yolksurface. Since the position of the embryo in the egg is at first determined by gravity, it is reasonable to suppose . . .

MANUFACTURERS of some forced draft incubators recommend that turkey eggs be removed from the incubator to a separate hatcher at 24 days’ incubation. This change involves a drop in incubation temperature from 99¾ to 97°F., cessation of turning, and a change in position from an angle of 45 degrees from horizontal to a horizontal position in which the eggs lie on their sides. The experiments reported herein were undertaken to determine the effects of transfer to the hatcher and to each of the hatcher conditions at 12, 15, 18, 21, 24, and 25 days’ incubation, respectively. The effects of hatcher temperatures of 93, 95, 97, 98, 99¾ and 102°F. were also determined. Egg length was measured prior to incubation so that its relation to hatchability under the various experimental conditions might be determined. Romanoff (1935) reported experiments in which turkey eggs were incubated for three weeks in a forced draft . . .

The rate of growth of the chick embryo depends upon an inherent growth rate, probably identical for all breeds. This rate is modified during incubation in direct proportion to a function of egg size. The increments in wet weight of the embryo are proportional to a function of the weight of the yolk sac, from the time of establishment of the circulation to the time of the changes preparatory to hatching. Both function and proportionality are probably identical for all breeds of chicken, regardless of egg size. The growth in weight of the allantois and the yolk sac have been measured quantitatively for the first time. The weight of the allantois in eggs of different sizes is roughly proportional to the two-thirds power of egg weight after the first three or four days of its growth. During the initial period of its development the relative size is apparently independent of breed, egg size, or embryo weight. The yolk-sac weight in eggs of different sizes is roughly proportional to the circumference of the yolk after a similar initial period of independent growth. Inclusion of the living material in the embryonic membranes in calculations of the rate of physiological processes of the embryo indicates that they are probably of the same order of magnitude throughout the incubation period rather than of sharply decreasing magnitude as supposed by some previous workers.

TURNING eggs has long been known to be necessary in artificial incubation to secure satisfactory hatches. Until the development of Mammoth incubators, however, little attention was given to the manner of turnings eggs or to the number of times they were turned a day. Eycleshymer (1907) appears to be one of the first to report the effect of not turning eggs. He found that he obtained only a 15 percent hatch when the eggs were not turned as compared to 45 and 58 percent hatches when the eggs were turned two and five times per day, respectively. He further states “that position of egg is a factor of little importance.” Jackson (1912) found that eggs turned twice daily hatched slightly better than those moved only once a day and also that “eggs laid flat and turned twice daily gave better results than those kept in any other position.” Comparisons between . . .

IT IS well known that the rate of egg production in the domestic fowl may be stimulated temporarily during seasons of normally short daylight periods by increasing the length of the daylight period with artificial light. Such stimulation is usually followed by a decline in egg production below the normal rate. Payne and Simmons (1934) presented an excellent paper on this subject and reviewed the literature to that date. Whetham (1933) showed that rate of egg production increases during seasons of increasing daylight in widely separated latitudes. Decline in rate of production begins before maximum daylight period is reached, however. The relationship of light to the ovulation cycle in the fowl is less well understood. Atwood (1929) showed that successive eggs in a clutch are usually laid at successively later hours in the day. An egg laid after 2 p.m. under natural day and night conditions is usually followed by . . .

BYERLY, Titus, and Ellis (1933) found that diets consisting of cereal grains, their by-products, alfalfa leaf meal, minerals, and cod liver oil are deficient in some factor, or factors, necessary for the production of eggs of high hatchability. This deficiency is satisfied by range, milk, and certain protein concentrates of animal origin, but not by certain protein concentrates of vegetable origin. Recent investigations by Halpin, Holmes, and Hart (1933) indicate that many diets for laying hens are deficient in vitamin G, and that the hatchability on such diets is low. Their basal diet, composed of yellow corn, oats, wheat bran, wheat middlings, meat scraps, common salt, and cod liver oil, plus scratch feed, grit, and crushed oyster shell, gave a hatchability of only 11 percent whereas the addition of skimmilk or chopped alfalfa hay to the diet raised the hatchability to over 70 percent. In order to determine if vitamin . . .

THE embryonic chick at the time of the laying of the eggs is usually subjected to the most extreme variations in environment it will have to withstand before hatching. In cold weather it may be quickly chilled, and during hot weather it may continue to develop, without pausing, for several hours before being stored under conditions that stop development while being held before incubation. Patterson (1910) found that the embryos show variation in development at the time of laying and Hutt and Pilkey (1930) have pointed out that some embryonic stages may be especially sensitive to external conditions, which may cause abnormal development or death, but would not affect the embryo at other stages. Hays and Nicolaides (1934) considered the variation, in embryonic development of fresh-laid eggs, among hens to be of primary importance, and stated that high hatching hens laid fertile eggs with more fully developed embryos than low . . .

INTRODUCTION DURING the course of an unpublished study to evaluate environmental factors affecting rate of egg production, it was deduced that age at first egg among genetically similar pullets should be closely related to daily hours of illumination. As a corollary, winter hatched pullets should mature earlier than spring hatched pullets. Evaluation of these relationships may enable poultry breeders to correct their genetic selection for early maturity in accordance with date of hatch or persuade them to limit comparisons to groups of pullets hatched during a very limited period. Selection is effective in proportion to the degree with which it reflects genetic variation rather than variation due to environment. Several studies of the effect of date of hatch on age at first eggs are summarized by Lippincott and Card (1939) and Jull (1940). Conclusions as to the effect of date of hatch on age at first egg drawn from these . . .

SEASONAL variation in the rate of egg production is associated with seasonal variation in length of day. The excellent paper of Whetham (1933) summarized a very large amount of data from a wide range of latitudes, all showing correlated changes in day length and rate of egg production. Kennard and Chamberlin (1931) showed that seasonal variation can be modified by use of supplementary artificial light, confirming the work of several earlier laboratory workers and of many poultrymen. Kennard and Chamberlin also showed the close relationship of body weight and rate of egg production. A good review of the earlier literature is contained in the paper of Callenbach, Nicholas and Murphy (1944). Several analyses of egg production data for the purpose of describing the relation of time in production and rate of production have been made. Harris et al. (1921) reported that annual production within a genetically similar flock maintained under . . .

APPROXIMATELY 50 percent of the cost of producing and marketing poultry meat consists of feed cost. Consequently, if it were possible to reduce, by any amount, the pounds of feed required to produce a pound of meat, it would increase the profits of the industry. If it were possible to obtain these lower feed costs through breeding it would indeed be worth our efforts. Therefore, a study of the efficiency of feed utilization, on a family basis, becomes an extremely practical as well as an interesting academic problem. Feed efficiency is a very complicated phenomenon affected by many physiological as well as environmental factors. There are at least two definite components, maintenance and growth, which enter into the gross efficiency of feed utilization by broilers. Maintenance requirement probably does not vary greatly per pound of chicken regardless of the weight of the broiler, although such factors as a decrease in . . .

EGGS from turkeys whose eggs averaged from 84–89 grams in weight, about the modal egg weight for the material reported, were reported by Marble and Margolf (1936) to have higher hatchability than eggs from females whose eggs averaged less than 84 or more than 89 grams. This finding is in agreement with the concensus of reported work on the effects of egg weight on hatchability of hen’s eggs, as given by Landauer (1937). Data reported in the present paper were collected during the 1937 breeding season at the National Agricultural Research Center, Beltsville, Maryland. The turkey females consisted of 156 birds, chiefly pullets, of several varieties * and crosses * and were mated to unrelated males. All birds were selected for small size, the average weight in January-February being approximately 11 pounds for the young breeding hens and 21 pounds for the young breeding toms. The small size of the breeding . . .

THE ability of the chick embryo to orient itself within the shell prior to hatching time is a subject of dispute. Hutt and Pilkey (1934) stated that if eggs are placed horizontally on a tray on the eighteenth day, and not turned subsequently, all eggs which hatch are pipped on the upper surface. They stated further that eggs turned on the nineteenth and twentieth days are pipped about equally on upper, lower, and intermediate surfaces. They presented no data to support their statements. Waters (1935a) presented data for 225 eggs turned four times daily after the seventeenth day and for 225 controls not turned after the seventeenth day. The turned eggs were pipped about equally on all surfaces, as Hutt and Pilkey stated, but the unturned eggs were also pipped about equally on all surfaces. Byerly and Olsen (1936) reported that about 5 percent of eggs not turned after the . . .

JULL (1932) points out that fertile eggs may be produced shortly after copulation and enumerates the number of hours elapsing from time of copulation to production of the first fertile egg as found by the following investigators: Gilbert (1905), 39 to 65 hours; Pearl and Surface (1909), 72; Coste and Gerk (1910), 28; Philips (1918), 23; Erickson (1924), 72; Fronda (1926), 20; and Dunn (1927), 21. Nicolaides (1934) found that the time elapsing between mating and the laying of the first fertile egg varied with different matings from 19.5 to 238 hours with an average of 66.2 hours. It was concluded that fertilization in the hen may occur in the upper end of the albumen-secreting portion of the oviduct. Waite (1911) secured 50 percent fertility on the third day and 70 percent fertility on the fourth day after mating. Maximum fertility was reported by Crew (1926) to have been reached . . .