Effects of electrical field on hatchability performance of eggs from a layer-type breeder

1. Eggs from a layer-type breeder flock (Baladi, King Saud University) between 50 and 63 weeks of age were used in three trials to study the effects of electrical field (EF) during incubation on albumen and yolk heights, incubation temperature, egg weight loss and hatchability traits. The effects of egg size and eggshell characteristics on hatchability traits of eggs incubated under EF were investigated. 2. Eggs were weighed and graded into three weight classes (small, medium, and large). The physical dimensions, eggshell characteristics, and conductance of eggs were examined. The incubator was divided into two compartments for the control and EF treatments. Two aluminium plates were fitted on the inside walls of the EF compartment, face to face, and connected to a step up electric transformer. Eggs were exposed constantly to the EF during the first 18 d of incubation at the level of 30 kV/m, 60 Hz. 3. Egg size influenced the physical dimensions and eggshell characteristics of eggs. Large eggs had higher egg weight, egg surface area, egg volume, eggshell conductance, and eggshell weight and lower yolk weight percentage than medium or small size eggs. Small eggs had lower egg length and higher egg density than large or medium size eggs. Large eggs had higher eggshell thickness than small size eggs. 4. EF incubation of eggs raised incubation temperature by 0.06 degrees C, and increased the percentage of egg weight loss, hatchability, and weight of hatching chicks and reduced the early embryo deaths, and length of incubation by approximately 9.8, 19.6, 1.7, 62.1 and 2.1%, respectively. 5. There was no significant difference between the two incubation treatments in the heights of albumen and yolk of incubated eggs, percentages of late embryo deaths, and pips with live and dead embryos. Hatchability traits were not significantly influenced by egg size. 6. It was concluded that EF incubation of eggs increased hatchability, chick-hatching weight, and reduced the length of incubation of Baladi eggs. Differences in the physical dimensions and eggshell characteristics of eggs did not influence hatchability traits of eggs under EF incubation.     

Inter-relationship between egg weight, parental age and embryonic development

A clear positive correlation was evident between egg weight at setting and embryo weight at 18 d of incubation for eggs laid at or after 32 weeks of age. The weight of embryos from the same size eggs were found to depend upon a curvilinear function of the age of parent flock, with the largest increase in embryo weight occurring between 28 and 32 weeks of age. Hatching weight was highly correlated with egg size at setting. Flock age had no effect on hatching weight from a particular sized egg. Within any of the five ages studied, chicks from smaller eggs tended to hatch slightly (but not significantly) earlier than those from larger eggs.     

种蛋孵化期失水率及蛋壳气孔密度与孵化率的关系

测定了海佩科和罗斯种蛋孵化期间失水率及蛋壳气孔密度,研究其与出雏之间的关系。结果表明:未出雏的种蛋失水率较高,且蛋重愈大,失水愈多。罗斯科蛋失水率较高。蛋壳气孔密度影响胚胎气体交换,未出雏的死胚蛋壳气孔密度显著较低。     

长鬣蜥繁殖生态的研究

2004～2005年,对人工饲养的长鬣蜥繁殖行为和生态习性进行了研究,结果表明：3～7月为长鬣蜥的繁殖期,繁殖行为主要表现为发情求偶、交配和产卵,5～6月为产卵高峰期,每条成熟的雌蜥年产卵2～3窝,平均窝卵数12（7～18）枚;雌蜥每窝产卵间隔33～45 d不等;平均单卵重3.06（2.80～3.50）g;卵径2.63 cm×1.18cm。在自然孵化温度和90%～95%的湿度下孵化期为60～98 d,孵化率52.34%,长鬣蜥幼体初生个体重2.50 g,体全长（头体＋尾）14（4＋10）cm。     

孵化期间鹅种蛋失重及其孵化效果的研究

本试验通过对不同品种鹅种蛋在孵化过程中的失重及孵化效果进行研究。结果表明,种蛋1 d~28 d平均失重率以莱茵鹅最高,与豁鹅、籽鹅比较差异显著(p<0.05),而豁鹅与籽鹅比较,差异不显著(p>0.05)。受精率以莱茵鹅最高,与豁鹅比较差异达到了显著水平(p<0.05),与籽鹅比差异极显著(p<0.01)。受精孵化率籽鹅与豁鹅、莱茵鹅比较,差异分别达到了极显著水平(p<0.01)和显著水平(p<0.05)。入孵蛋重与28d胚蛋重呈强正相关,失重率随蛋重增加而降低;蛋重越大,初生重也随之增大。     

Studies on ticks of veterinary importance in Nigeria. VI. Comparisons of oviposition and the hatching of eggs of Hyalomma species

Fully engorged Hyalomma spp. in Nigeria oviposited greater numbers of eggs than those partially engorged. Hyalomma impressum was a more prolific egg layer than H. rufipes, H. impeltatum and H. truncatum. The variations in the egg output as well as the recognizable peaks in the number of eggs during oviposition were described for each species. No species of Hyalomma below the engorged weight of 0.2 g oviposited; oviposition started with ticks of weight 0.3 g. Eggs produced by ticks weighing below 0.3 g did not hatch; the highest percent egg eclosion occurred with ticks of weight 0.6 g (H. rufipes) and 0.7 g (other Hyalomma species). The pre-oviposition, oviposition and eclosion periods were shortened when eggs were laid and incubated at high temperatures, although the number of oviposited eggs did not increase significantly. At the standard temperature of 24 degrees C, the longest eclosion period was seen in the eggs of H. rufipes (41 days) while those of H. truncatum, H. impressum and H. impeltatum were similar to each other (29 days). Only eggs of H. rufipes hatched at an incubation temperature of 15 degrees C. Eggs of Hyalomma species laid at the same time hatched over a 2--4 day period, except at 15 degrees C when the hatching period of H. rufipes lasted 10 days. The eclosion period was longest in the earlier ovipositions and shorter in the later ones. It is suggested that some intrauterine larval development might have started in the eggs before they were released at a later oviposition period. The percentage mortality of eggs at various temperatures showed that eggs of H. rufipes were more tolerant of low temperatures than those of H. impressum, H. truncatum and H. impeltatum, while the eggs of the latter 3 species were more tolerant of high temperatures than those of H. rufipes. The relevance of these results of the distribution and abundance of the Hyalomma species in Nigeria was discussed.     

Factors affecting the weight and water status of the chick at hatch

1. Variation in chick weight at the moment of escape from the shell is accounted for by the fresh weight of the egg, the weight lost from the egg during the incubation period and the weight of the shell and residues at hatch.

2. Over 97% of the variation in chick weight at hatch can be explained by two factors, fresh egg weight and weight loss during incubation. These two factors still account for a high (87%) proportion of the variation in chick weight at 21 d after setting when chicks would normally be removed from the hatcher.

3. The water content of the true chick and the residual yolk sac are both affected by water loss from the egg during incubation and account for the differences in the weight of the whole chick at hatch from eggs of the same size.

4. When the fluid reserves within the egg become exhausted in the few days before hatch, the water: dry weight ratio of the yolk rather than embryo is maintained despite variation in water losses between eggs.     

蛋重和蛋形指数对拉萨白鸡种蛋孵化效果的研究

为研究拉萨白鸡种蛋蛋重和蛋形指数（纵径/横径）对孵化效果的影响,在相同孵化条件下,选用3世代47周龄拉萨白鸡种蛋,按蛋重分组进行孵化,Ⅰ组（≤45.0 g）蛋形指数为（1.27±0.05）,Ⅱ组（45.1-50.0 g）蛋形指数为（1.27±0.05）,Ⅲ组（50.1-55.0 g）蛋形指数为（1.27±0.05）,Ⅳ组（55.1-60.0 g）蛋形指数为（1.28±0.05）,Ⅴ组（〉60.0 g）蛋形指数为（1.31±0.05）。结果表明,种蛋的蛋重越大,其纵径均值、横径均值、蛋形指数均值、受精率、入孵蛋孵化率、受精蛋孵化率和雏鸡初生重越大,即Ⅴ组（〉60.0 g）种蛋的蛋重均值、纵径均值、横径均值、蛋形指数均值、受精率、入孵蛋孵化率、受精蛋孵化率和雏鸡初生重均最大,分别为（61.03±0.82）g、（58.13±1.68）mm、（44.59±0.79）mm、（1.31±0.05）、98.15%、85.19%、86.79%和（42.48±1.98）g;Ⅱ组（45.1-50.0 g）的健雏率最高,为96.09%;Ⅰ组（≤45.0 g）的雏鸡初生重占入孵蛋重的百分比最大,为（69.91±2.71）%;蛋重与纵径、横径、蛋形指数呈极显著正相关（P〈0.01）。因此,蛋重和蛋形指数对拉萨白鸡种蛋的孵化率影响较大,应选择较大种蛋（〉45.0 g）,蛋形指数的范围则较宽,在≥1.27时即可以达到较理想的孵化效果。     

Effect of intensity of eggshell pigment and illuminated incubation on hatchability of brown eggs

The effects of intensity of brown eggshell pigment (light (LBP), medium (MBP) and dark (DBP)) and light intensity during incubation (low and high, 900 to 1380 and 1430 to 2080 lux, respectively) on eggshell characteristics, embryonic growth, hatchability traits, chick hatching weight and hatching time were investigated using eggs from a meat-type breeder (Hybro) flock at 32, 36 and 41 weeks of age in three trials. With eggs of similar weights the intensity of brown pigment was not associated with eggshell weight and thickness, and did not influence embryo weight and egg weight loss during incubation. The shade of brown pigment of eggs laid by young hens influenced the percentage hatchability (HP) of eggs incubated under light. Illuminated incubation improved HP of LBP eggs (compared with MBP and DBP eggs) from 32- and 36-week-old hens, but had no significant effect on HP of eggs from 41-week-old hens. Light intensity during incubation did not influence egg weight loss. High intensity of light during incubation reduced HP and increased early death percentage (EDP) in the LBP and MBP groups, and did not influence HP and EDP in the DBP group. Brown eggshell pigment and intensity of light during incubation did not influence hatching time. It is concluded that the shade of brown pigment, intensity of light during incubation and age of the breeder hens influenced the hatchability performance of embryos from brown eggs. Light during incubation improved the hatchability of embryos in light brown eggs laid by young hens and the shade of brown pigment of eggs laid by older hens did not influence hatchability under illuminated incubation. High intensity of light during incubation reduced hatchability of light and medium brown eggs, but not the dark brown eggs.     

Effects of high concentrations of dietary vitamin E and ethoxyquin on the performance of laying hens

1. Three experiments were carried out with light strain laying hens to evaluate the effects of relatively high doses of dietary vitamin E (125 mg/kg food) or ethoxyquin (EQ) (250 mg/kg food) on their laying performance. The control diet contained 5 and 125 mg/kg vitamin E and EQ, respectively. The experimental diets were fed either from one or 32 weeks until 88 or 89 weeks of age. 2. The two antioxidants did not affect the growth of the pullets, age at first egg, final body weight, average egg weight or relative abdominal fat pad size and liver weight at the termination of the experiments. In two out of three experiments, vitamin E and EQ did not affect egg production, food efficiency or mortality; in the third experiment vitamin E significantly (P less than 0.05) improved egg production and food efficiency after an outbreak of Newcastle disease which occurred at 34 weeks of age. EQ significantly reduced mortality during the course of this experiment, but did affect the variables of performance. In two experiments vitamin E consistently improved shell density, although a significant effect was observed in only one of the eight determinations carried out. EQ did not affect this variable. 3. The uterine muscle was more susceptible to oxidation than the drumstick meat, as evaluated by TBA values. In both tissues, vitamin E significantly and consistently decreased TBA values and restricted their increase during incubation, while EQ was less effective, particularly in the drumstick meat. 4. It is concluded that increasing vitamin E and EQ concentrations in diets of laying hens have no effect on the decrease in egg production due to aging. However, vitamin E may minimize the decline in egg production and food efficiency following the outbreaks of some diseases and slightly improve--under certain yet undefined conditions--shell density.     

Failure to turn eggs during incubation: effects on embryo weight, development of the chorioallantois and absorption of albumen

Turning eggs during incubation is essential for good hatchability. In the present paper additional effects on the development of the chorioallantois, absorption of albumen and growth of the embryo are recorded. The ability of an unturned egg to hatch was not affected by egg weight, egg shell porosity or water loss during incubation. The ability of the chorioallantois to spread around the inner surface of the inner shell membrane and the degree of absorption of the residual albumen affected the growth of the embryo and its ability to hatch. Unturned eggs hatched later than eggs which were turned throughout incubation.     

赤麻鸭（Tadorna ferruginea）的人工孵化初探

2011年4—5月,对徐州金桥禽业发展有限公司养殖的赤麻鸭所产的44枚卵进行了人工孵化研究。其中43枚卵受精,出雏35枚,4枚在孵化中期死胚,5枚为27d落盘后啄壳困难而死亡,受精卵的孵化率为81．40％。孵化温度前期为38．5℃;中期为38．2℃;后期为37．8℃,落盘后温度降为37．5℃。赤麻鸭卵鲜重为（79．80±6．72）g,长径为（66．10±2．53）mnq,短径为（46．40±1．45）／mm,卵形指数为1．43±0．06,出雏后的卵壳等剩余物质重（12．60±1．07）g,新生雏鸟重占鲜卵重的（67．20±3．71）％。卵总失重率为17％。孵化期间的卵重（Y）与孵化天数（x）之间的线性方程为Y=一0．9071x＋81．019（R2=0．9997,P〈0．01）,根据卵失重方程可以比较准确地推算出赤麻鸭卵的孵化天数。     

The effects of dietary fat and bird age on the weights of eggs and egg components in the laying hen

1. A low-fat diet or an isoenergetic and isonitrogenous high-fat diet containing 55 g maize oil/kg were fed to laying hens at different stages during the laying year in two experiments. 2. Feeding the high-fat diet to young hens resulted in a rapid increase of 2.5 g in egg weight, made up of increases in both yolk and albumen weights. 3. Switching the diets at 50 weeks caused changes in egg weight that were accounted for entirely by changes in egg albumen weight. 4. Feeding the high-fat diet from 46 weeks in a second experiment increased egg and egg albumen weights by 1.26 and 1.34 g respectively. 5. The increase in egg weight with age was associated with a greater increase in the proportion of yolk, at the expense of albumen, compared to egg weight increases related to dietary fat. 6. It is concluded that dietary fatty acids increase egg weight by a mechanism different from that causing age-related increases in weight and that the mechanism involves a stimulation of oviduct protein synthesis.     

Effects of photoperiod during incubation on embryonic and post-embryonic development of quail and chickens

The effect of light during incubation on embryonic and post‐embryonic development of White Leghorn chickens and Northern Bobwhite quail was determined. The treatments were: (a) 12 h light followed by 12 h dark (12L—12D), (b) 24 h light (24L—0D) and (c) 24 h dark (0L—24D) per day throughout incubation.

The development of the embryos of both species was accelerated by increasing the length of exposure to light during incubation. There were no differences in hatchability, weight at hatching, or at 4, 8, 12, 16 or 20 weeks of age. The incidence of healed navels was increased with greater length of exposure to light during incubation. No differences in egg production due to treatment were detected.     

蛋重对孵化失重、羊水及尿囊液量、雏鸡初生重影响的研究

通过孵化实验,研究了蛋重对孵化失重、羊水及尿囊液量、雏鸡初生重的影响.结果表明,蛋越重,失重越大,羊水及尿囊液的量越多,雏鸡初生重也越大;蛋重在60.0～64.9 g范围时,失重率最大;蛋重与雏鸡初生重呈强正相关,相关系数为0.868.     

Latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (Sceloporus undulatus)

Geographic variation in life‐history traits among populations of wide‐ranging species is influenced by both spatial and temporal aspects of the environment. Rarely, however, are the effects of both aspects examined concurrently. We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi) and southern (Florida) populations, spanning nearly the full latitudinal range of the species, to examine amongpopulation differences in strategies of reproductive energy allocation. Adult females from the southern population were smaller, and produced fewer and smaller eggs in their first clutches than did females from the more northern populations. Southern females were more likely to produce a second clutch, and second clutches were smaller than first clutches for females from the 2 northern populations. Together these trends eliminated population differences in overall reproductive output after accounting for body size. The trend for greater reproductive energy to be allocated to first clutches at higher latitudes, and to later clutches at lower latitudes is corroborated by published data from field studies on multiple populations. Distributing reproductive effort by producing more clutches of smaller eggs may be an adaptive response to the long season available for egg incubation and lizard activity in sub‐tropical southern environments. In contrast, allocating greater resources to early reproduction may enhance maternal fitness in the relatively short activity seasons that characterize more northern sites.     

Effects of egg mass and percentage mass loss during incubation on hatchability of eggs of the rock partridge (Alectoris graeca)

1. The effects of initial egg mass (IEM) and percentage mass loss during incubation (%ML) on hatchability of rock partridge eggs were investigated. 2. Eggs at the extremes of IEM had lower fertility and embryonic mortality. 3. Eggs at the extremes of %ML also had low fertility and hatchability was disproportionately reduced in eggs that had lost less mass during incubation. 4. Chick mass was a function of both IEM and mass lost during incubation. 5. In these respects rock partridge eggs are similar to that of other domesticated species of poultry.     

Changes in luteinizing hormone-containing gonadotrophs after moulting induced by fasting and zinc in laying hens (Gallus domesticus)

The purpose of the present study was to investigate egg production performance, immunohistochemical (IHC) identification, localization and morphological characterization of moulted hen’s pars distalis luteinizing hormone (LH) gonadotrophs. This system has been validated for chicken LH by immunodetection of purified hormones on dot blots, western blotting and by specific labelling of cells on sagittal sections of chicken pituitaries. This study showed that egg production and egg weight increased significantly after zinc-induced moult when compared with fasting-induced moult. Luteinizing hormone-gonadotrophs are of numerous shapes and distributed throughout the adenohypophysis, with densely populated regions on the margins of pars distalis. Moulting of laying hens was associated with a significant increase in immunoreactive LH gonadotroph cell count and cell size, which peaked at the subsequent production stages. Zinc-induced moulting also caused a significant increase in LH gonadotroph cell size as compared with fasting-induced moulting. The nuclear size of LH-positive cells was distinct during decreased egg production. Our results validate the use of ovine LHβ antibodies for the IHC localization of chicken LH gonadotrophs. This technology was further applied to the characterization of the shape and morphological changes of gonadotrophs as a function of the egg production status of the birds.     

Reduced egg shell permeability affects embryonic development and hatchling traits in Lycodon rufozonatum and Pelodiscus sinensis

The response of embryos to unpredictable hypoxia is critical for successful embryonic development, yet there remain significant gaps in our understanding of such responses in reptiles with different types of egg shell. We experimentally generated external regional hypoxia by sealing either the upper half or bottom half of the surface area of eggs in 2 species of reptiles (snake [Lycodon rufozonatum] with parchment egg shell and Chinese soft‐shelled turtle [Pelodiscus sinensis] with rigid egg shell), then monitored the growth pattern of the opaque white patch in turtle eggs (a membrane that attaches the embryo to the egg shell and plays an important role in gas exchange), the embryonic heart rate, the developmental rate and the hatchling traits in turtle and snake eggs in response to external regional hypoxia. The snake embryos from the hypoxia treatments facultatively increased their heart rate during incubation, and turtle embryos from the upper‐half hypoxia treatment enhanced their growth of the opaque white patch. Furthermore, the incubation period and hatching success of embryos were not affected by the hypoxia treatment in these 2 species. External regional hypoxia significantly affected embryonic yolk utilization and offspring size in the snake and turtle. Compared to sham controls, embryos from the upper‐half hypoxia treatment used less energy from yolk and, therefore, developed into smaller hatchlings, but embryos from the bottom‐half hypoxia treatment did not.     

The effects of a protein deficiency on egg composition

Eggs were collected from groups of pullets receiving 9, 14 or 20 per cent dietary protein and the component parts were separated and weighed. The reduction in egg weight associated with protein deficiency was found to be due to reductions in all components, but yolk and shell weight changed proportionately less than total weight and albumen weight proportionately more. The resulting increase in percentage yolk was found to be of similar magnitude to that expected from a consideration of the relationship between egg size and yolk size in birds receiving adequate protein. In a similar way the increased proportion of shell apparently reflected only the relationship between egg size and surface area in eggs collected when the birds were 52 weeks of age but at 67 weeks a real increase in shell thickness on the deficient diet was also indicated.