Egg Production Curves Research Articles

乳牛の泌乳曲線および鶏の産卵曲線あてはめにおける重みつき最小二乗法

乳牛の泌乳曲線および鶏の産卵曲線あてはめにおける重みつき最小二乗法

Effects of Intermittent Watering on the Performance of White Leghorn Hens

Three experiments were designed and conducted to study the effects of intermittent watering on the performance of laying hens. A total of nine intermittent watering treatments were evaluated in the experiments. Providing water on an intermittent basis had no statistically significant effect on hen-housed egg production, hen-day egg production, egg weight, feed per dozen eggs, egg specific gravity or average body weight. In experiment 3, the hens receiving water ad lib. had significantly (P<.05) lower mortality than hens on the intermittent watering treatments. The egg production curves do not indicate that intermittent watering during times of high temperature and peak egg production had any detrimental effects on egg production.

Seasonal Commercial Egg Production Curve Differences

The statistical and economic significance of seasonal differences in commercial egg production curves were assessed. The time profile of both the number and weight of eggs laid by White Leghorn pullets was found to differ significantly statistically between housing seasons. Imputed differences in the value of gross egg receipts suggest that seasonal production differences as well as seasonal egg price patterns should be considered in formulating commercial layer flock replacement plans.

Effects of electromagnetic fields on fecundity in the chicken.

Egg production was reduced when young laying hens were kept in contact with metal cages while being continuously exposed to the following cw fields: a vhf field at a frequency of 260 MHz, with an incident power that decreased from 100 to 4mW during the experiment; a uhf field at a frequency of 915 MHz, with an incident power of 800 mW during the first 2.5 weeks, zero during the following week, and 200 mW for the remainder of the experiment; a uhf field at 2.435 GHz, with an incident power of 800 mW; an elf electric field at a frequency of 60 Hz, with a calculated value of field strength of 1600 V/m; an elf magnetic field at 60 Hz, with a value of magnetic flux density of 1.4G. With the exception of the hens exposed to the uhf field at 915 MHz, all other treated groups laid significantly less eggs than the controls (p smaller than or equal to 0.01). This reduction (similar 15% less than the controls) began with the first 4-week production period. The egg production curves for the hens exposed to the vhf field at 260 MHz and to the uhf field at 2.435 GHz were approximately the same beginning with the sixth week of production, and they maintained comparable production levels for the remainder of the experiment. An 8% total drop in production also was experienced in the group of birds exposed to the 915-MHz field, which pulsed because of equipment failure. Egg production rate curves for the birds in the elf electric and magnetic fields were substantially different from those exhibited by birds in the other electromagnetic fields. The birds in the E-field regained a production level comparable to the controls after 11 weeks production, whereas those in the B-field dropped to 31% production, which was approximately 40% poorer than the controls by the twelfth week of production. Fertility of cocks and hens was not affected by continuous low-power vhf and uhf near-zone electromagnetic exposure or elf electric or magnetic field treatment. Fertility was exceptionally good, except for the controls and the hens exposed to the elf electric field. The hatchs of fertile and of total eggs were not significantly influenced by exposure to any of the five fields. A considerably lower incidence of male chicks was noted in the elf magnetic field treatment (32.3%). The sex ratio in the other groups appeared to be relatively normal. No macroscopic abnormalities attributable to treatments were noted in the chicks hatched or in the dead embryos.

Lack of mutagenicity of hycanthone in Habrobracon serinopae females

The pattern of egg production by females fed the hycanthone indicates that there was no detrimental effect on the ability of these females to produce eggs. This indicates that no change was induced in the general physiology of this insect. The absence of the typical depression in the egg production curve, like that seen after x irradiation of virgin females, and the high hatchability of haploid eggs show that the feeding of hycanthone does not induce dominant or recessive lethal mutations in meiotically or mitotically active cells. (auth)

QUANTITATIVE GENETICS OF FERTILITY. III. A NEW MODEL FOR INTERSTRAIN LIFETIME EGG PRODUCTION COMPARISONS

A new model for use in theoretical and practical studies of egg production is derived: N(t) = (1−e−ξ(t–to))e−α(t–tq), where N(t) is the number of eggs laid on day t; ξ is the rate of increase in egg production; α is the rate of decrease in egg production; tois the day of initiation of egg-laying; tqis the day of cessation of egg-laying. Egg production curves for Drosophila melanogaster strains were fitted using non-linear least squares regression analyses such that all parameters in the model and their errors were generated simultaneously. The goodness-of-fit of the model to the observed data was precise. The experimental evidence showed that parameters α and tqwere basically describing the genetic components of egg production in females whereas parameters ξ and toexhibited additional components, the interactions between males and females. Expressions derived from the model, tmax, the time of maximum production, N(tmax), the maximum production at this time and T(to,tq), the production over lifetime, gave results consistent with the observations.

Breeding

The Seasonal Distribution of Egg-Production: The normal Egg-Production Curve. F. M. Fronda. The Philippine Agriculturist, Vol. XVII, No. 1. College of Agriculture, University of the Philippines.Summary and Conclusions:1.The monthly percentages of egg production of Cantonese, Native, White, Leghorn, and Barred Plymouth Rock breeds of chickens for five years, 1922 to 1927, and of Rhode Island Red for four years, 1922 to 1926, are presented in this paper.2.A comparison of the egg production curve of the Cantonese breed is made with that of the Black Orpington in Australia and of the Barred Plymouth Rock in the United States.3.The data presented show conclusively that there is a definite type of egg production curve in this country.4.The egg production curve in this country is very similar to those of the United States and Australia, although they do not exactly coincide as to the time of the year.5.There is sufficient reason to believe that the egg production curve of chickens in this country is perhaps more nearly like the normal egg production curve of the primitive kinds of fowls than curves of egg production observed in the temperate countries.6.The laying year may be roughly divided into two periods, the reproductive period, January to June, and the rest period, July to December.7.The reproductive life of a chicken is a succession of the reproductive period and of the rest period, which correspond very closely to the two distinct dry and wet seasons of the year.8.The annual molt coincides in general with the gradual drop of egg production which begins about July and ends about December.9.If fowls start in their reproductive processes early in the season, a second or even a third clutch of eggs may be laid during the favorable period of the year.10.The number of eggs laid by the hens during each of these periods depends upon the age and individuality of the birds, the amount of care given them in feeding, housing, and management, and upon other conditions of the environment.