For the farmers and hatcheries of keeping parent stock of broiler, the establishment of techniques to keep them with less expenses of feed and obtain more hatching eggs per bird is extremely important. For this purpose, sexual maturity should be delayed artificially to get larger eggs from the beginning of the lay.
Feed restriction during growing period is a useful and most commonly used technique to delay onset of lay. Another method using a drug effective to block release of gonadotrophic hormone from anterior pituitary is also often used experimentally. The drug, I.C.I. 33, 828, is produced by Imperial Chemical Industry in England.
The present report is the result of three comparable methods of treating growing pullets of breeders with restricted feeding, fasting and administration of I.C.I. 33, 828. The experiment was carried out with 201 pullets of New Hampshire _??__??_ × Rhode Island Red _??__??_ hatched on December 16, 1966. Feed restricted group was divided into three sub-groups:
Treatment No. 1 (Skip-a-day)-fed every other days for 88 days from 60 to 147 days of age.
Treatment No. 2 (Fasting A)-fasted for 6 days from 120 to 125 days of age.
Treatment No. 3 (Fasting B)-fasted for 6 days from 134 to 139 days of age.
Three other groups were treated with I.C.I. 33, 828. They received the compound of I.C.I. 33, 828 at 0.002%, 0.004% and 0.008% levels in the feed for 30 days from 134 days of age when 10 birds of 151 pullets started to lay. The birds belong to control group were fed ad libitum without the drug.
1) Average body weight of skip-a-day group was 77% of that of control at the time the treatment terminated, and after that it recovered slowly until 230 days of age when there was no significant difference between them. Whereas in Fasting A and B groups, the body weight at the end of the treatments were 79% and 87%, of that control and once they were returned to full feeding, they recovered to the level of control immediately within 2 and 1 weeks, respectively.
2) Feed consumption of skip-a-day was 73.4% of the control during the treatment period. However, no difference was observed in the consumption from 148 to 182 days of age. After release from fasting at Fasting A & B, there was no significant difference in feed intake from the control group. The groups treated with I.C.I. 33, 828 consumed 73-79% of the control during the treated period and the more the amount of the drug in feed, the more reduced feed consumption.
3) Sexual maturity of pullets was significantly delayed by feed restriction and the administration of I.C.I. 33, 828. Mean ages at the first egg of the control was 149.2 days and experimental groups were delayed 6-22 days from the control. Fasting A & B showed almost same sexual maturity and the difference in age of fasting did not affect on the age of the maturity. The groups treated with I.C.I. 33, 828 showed delayed sexual maturity and the more the dose the later the maturity. 0.002% and 0.004% of I.C.I. 33, 828 could not depress to become the maturity completely even during the treatment period, and some of the birds started to lay before the treatment finished. Especially in the group of 0.002%, 15 birds out of 25 laid during the treatment, although the production during the period was as low as 1-3 eggs per bird in 10 days. Only 0.008% level could prevent onset of lay perfectly during the period of medication.
4) Feed restriction and treatment with I.C.I. 33, 828 had marked effects upon enlarging egg size. Significantly larger egg sizes, 0.8-5.7gr. larger than the control, were obtained in the treated groups except in Fasting A. Those significantly large egg sizes could not be maintained until 230 days of age when there was no difference in the size between the groups.
5) There was no significant difference between the groups in egg productions until 500 days of age and during 365 days of laying period after 1st egg.

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One hundred and twenty White Plymouth Rock female chicks each, hatched in either March or June, 1968, were separated into 4 duplicated lots of 15 chicks each at 8 weeks of age. Control replacer diet was given to 2 duplicated lots of the chicks, who reared on control starter and grower diets. High energy-low lysine replacer diet was given to the rest, who reared on low lysine starter and grower diets. Conventional layer diet were given to all of the pullets after 24 weeks of age. Chicks in one duplicated lots out of 2 on each of the replacer diets were fed ad libitum and those in the other lots were fed alternatively throughout the experimental period from 8 to 60 weeks of age.
Alternative feeding of conventional replacer and layer diets retarded growth rate of pullets hatched in March by 14% and sexual maturity for 13 days, but showed actually no effect on the growth rate of pullets hatched in June. Average feed consumption in layer house was 12% less than that of the control, making final average body weight 460g lighter. No difference was observed on egg production, egg weight, mortality and other laying performance.
The feeding program of high energy-low lysine replacer diet resulted in severe growth retardation by 27% in average and 28% decrease in feed consumption, regardless to the hatching month. However, the program gave favorable results on the performance in laying period, such as delayed maturity, lighter final body weight. Egg weight of pullets hatched in March was significantly heavier and their hatching egg production was more on this feeding program than those on the control ad libitum feeding program. No significant difference on egg weight and hatching egg production of pullets hatched in June were observed between two programs.
The severest growth retardation and feed consumption was observed in alternative feeding program of high energy-low lysine replacer diet and conventional layer diet. The feeding program gave favorable results on the performance in laying period, such as delayed maturity, 637g lighter final body weight. Egg weight of pullets hatched in March was again significantly heavier and hatching egg production was more on the program than those on the control program, but no significant difference on egg weight and hatching egg production of pullets hatched in June were observed between two programs.

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Chicken plasma esterases were examined by starch gel electrophoresis. Starch gel was prepared by Lush's alkalin buffer system with a slight modification of the addition of eserine sulfate at the concentration of 10^-5M. Esterases were detected by dye-coupling method, using alpha-naphthyl butyrate as the substrate and fast blue RR salt as the dye coupler.
The Band VII is the eserine resistant esterase and the results of matings show that the activity of Band VII is controlled genetically by two alleles at a single autosomal locus. The author proposes to nominate the locus as Es-2 and the alleles as Es-2^A and Es-2^a, respectively. Es-2^A is dominant to Es-2^a and the bird of genotype Es-2^a/Es-2^a lacks Band VII.

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Using the White Leghorn hens of 205, 270 and 305 days of age respectively, three experiments were carried out to study the influence on egg performence of laying hens of various amounts of amino acids supplemented to the negative control corn-soya diet containing 11% of crude proteins. In each experiment, 50 hens were randomly assigned to five diet groups. Except for methionine which was of DL-form, all of the amino acids used were of L-form and had more than 98% purity. A corn-soya diet containing 16% of crude proteins served as positive control.
In all experiments, the negative control diet administered singly was found to be unsatisfactory in maintaining a high rate of egg production. On the other hand, a diet to which the essential amino acids were supplemented (15% N equivalents) at the level twice as much as the N.R.C. or Johnson and Fisher Standard was as effective as the positive control diet. A diet to which the essential amino acids were supplemented (12.7% N equivalents) at the level 1.5 times as much as the Standard also worked fairly well, although egg production on this diet was 5% lower than that on the positive control diet. Even the addition of certain kinds of non-essential amino acids, such as glutamic acid and asparatic acid, proline and serine as well as essential methionine and lysine, to this diet (15% N equivalents) failed to improve the egg production rate. However, a diet containing six non-essential amino acids in the same ratio to the positive control diet was found to be as effective as the positive control diet.
It is concluded that not only the balance of the essential amino acids but that of the non-essential amino acids in diet are important for the maintenance of high rate of egg production of laying hens.

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Available energy of 6 samples of dehulled rice stored for 1, 2 or 3 years was estimated by bioassay procedure, using 270 male and 270 female meat-type chicks. Ten percent of yellow corn out of 50% and 57.1% in corn-soy type chick starter and broiler finisher, respectively, were replaced with either cellulose alone or a mixture of soybean oil and cellulose (7:3), to prepare 3 standard diets, containing 2.49, 2.84 and 3.14kcal metabolizable energy per kg diet. All of yellow corn in basal chick starter and broiler finisher, containing 2.84kcal/g, was replaced with dehulled rice to prepare test diet.
Body weight gain per unit of feed, i.e. feed efficiency g/kg, on 3 standard diets was in proportion to dietary energy level at 4 and 7 weeks of age. Using this linear relationship between dietary energy and body weight gain per unit of feed, available energy of 6 samples of rice was estimated as described previously3, 4). At 3 weeks of age, excreta of chicks on all of experimental diet for 48 hours were collected and analyzed chemically to estimate nitrogen collected metabolizable energy, using chromic oxide as an indicator.
Chicks fed 6 samples of rice grew almost as fast and as normal as chicks on the standard diet of 2.84kcal/g, except that skin and shank of them faded in color due to lack of pigment in rice. No significant difference was observed among rices of different strain, croped at different place in this country and stored for different period. Average and standard deviation of available energy estimated at 4 and 7 weeks of age and those of metabolizable energy estimated at 3 weeks of age were 3.45±0.07, 3.57±0.08 and 3.54±0.05kcal/g air-dry matter, respectively. Crude protein content of dehulled rice was 8.0±0.76%.

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Plasma samples of the pea fowl were examined by starch-gel electrophoresis. Two types of prealbumins were observed. One type of bird possessed one band and another type of bird possessed two bands in the prealbumin region. The two bands were stained by nigrosine more faintly than the one band of another type of the birds. Genetical studies on the prealbumins are in progress.

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Nitrogen corrected metabolizable energy of 7 samples of feed ingredient was determined by growing male chicks of 3-week-old, laying hens of 2-year-old and Japanese quails of older than 24 weeks.
Metabolizable energy of a diet fed at level of 80 or 60% of full-feeding was confirmed to be actually equal to that estimated on full-feeding program. Accordingly, the estimation of metabolizable energy of various feed ingredients was carried out on full-feeding program.
The tendency was observed that metabolizable energy of high protein feed, i.e. soybean meal, fish meal and petroleum yeast, estimated by quails was slightly lower than those estimated by chicks and laying hens, as shown in Table 3. However, the difference was not significant statistically, therefore, metabolizable energy estimated by chickens could be used as an estimate of metabolizable energy by quail.

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