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The effect of sex-linked dwarf gene was investigated through comparison of dwarf hens with their full-sib normal sisters obtained by mating heterozygous males (DW/dw) to normal females (DW/_) from line F (used as maternal form for production of slow-growing colored chickens) with respect to the following traits: body weight, shank and keel length at 40 weeks of age, age of sexual maturity (at 50 % production), egg production, egg weight, feed intake, feed utilization, livability, fertility, hatchability and egg quality characteristics. The results demonstrated that the dw gene caused statistically significant reduction of body weight by 29.15 %, shank length by 20.17 %, keel length by 7 % and egg weight by 5.72 % (p<0.001). The hens with normal genotype attained sexual maturity 7 days earlier (p<0.001), but nevertheless, rate of lay was similar to that of mini forms. There were no considerable differences between both genetic groups with respect to livability percentage over the production cycle. Dwarf hens consumed by 23.38 % less feed (p<0.01) than normal sized hens and converted nutrients more efficiently by 12.69 % (p<0.05). The presence of dw gene in hen genotype increased the eggshell percentage, reduced egg yolk and albumen weights and had no effect on their quality. The positive effect of the sex-linked dwarf gene on economically important traits--feed intake and feed conversion, hatchability of eggs set, is a prerequisite for the development of more efficient broiler breeder hens for production of slow-growing chickens. [ABSTRACT FROM AUTHOR]

The new original egg laying lines T, P and N selected at the Institute of Agriculture -- Stara Zagora were used. Hybrid T♂ x P♀, P♂ x T♀ crosses were obtained and used for paternal line. Thereafter, the following breeding schedule of paternal and maternal lines was applied: Group I - (P♂xT♀)♂ xN♀; group II -- (T♂xP♀)♂ xN♀; group III -- T♂xN♀; and group IV -- P♂xN♀. The production traits of original and hybrid birds were recorded: live weight at the age of 8 and 18 weeks, age of sexual maturity in days, 150 days egg production, average egg weight -- at 2-week intervals until end of lay; livability, heterosis effect. The live weights of hybrids at 8 and 18 weeks of age were statistically significantly lower compared to original lines. The values of heterosis for this parameter were negative for all four hybrid combinations. The earliest beginning of egg lay occurred in (T♂xP♀) ♂ xN♀ (162.08 days of age) and P♂xN♀ (163.11 days of age). The relative (%) heterosis for age of sexual maturity of studied hybrid combinations had moderate to low negative values. Average egg weights of hybrids were higher and the values of heterosis -- positive for all four groups varying from 0.97% to 1.63%. The average 150 days egg production was lower in purebred lines compared to hybrids. The highest average 150 days egg production was determined in P♂xN♀ hybrids -- 142 eggs. The heterosis effect for egg production in hybrids was significant. [ABSTRACT FROM AUTHOR]

Eight hundred one-day-old female chickens from two White Plymouth Rock lines (line L and line K) and their reciprocal crosses obtained from 40 male and 480 females were used to form four genetic groups (LxL, KxK, LxK and KxL). Differences among genotypes, the direct and maternal additive effects, and the heterosis were investigated with regard to the following traits: body weight from 2 to 10 weeks of age and at 18, 26 and 30 weeks of age, age at sexual maturity, egg production per hen-day until 46 weeks of age, average egg weight (between 32 and 46 weeks of age), liveability during the production period, egg fertility, hatchability of set and fertile eggs. The results demonstrated a statistically significant effect of the genotype on body weight during the different age periods (p<0.001), age at sexual maturity (p<0.001), egg production (p<0.01) and livability (p<0.05). On the basis of analysis of direct additive effects, it could be concluded that line L was superior for obtaining combinations with more intensive growth rate. Although the lack of direct additive effect with respect to the other traits studied, there was a positive tendency favouring line K. Maternal additive effects had a substantial effect on body weight in most studied periods and livability, favouring line L. The heterosis was important for body weights at different periods of life (3.76-22.33 %), age at sexual maturity (-8.32 %) and egg production (8.25 %) with positive effects on these traits. The results pointed at a mutual complementary effect between both lines as a result of crossbreeding. [ABSTRACT FROM AUTHOR]

The issue of avian gene pool preservation should be linked to the development of a new trend in selection allowing rational use of the diversity of breeds and lines. Ten original chickens lines are reared in the Poultry Breeding Unit at the Institute of Agriculture, Stara Zagora: ?Z-80 B, ?Z-80 ?, Line ?, Line D, Line G, Line NG, Line ?, Line Ss, Line ChS, Line StR controlling their productivity through reproductive traits, live body weight at the age of 1 day, 5 months and 10 months, egg production and survival rate for the production period. The reproductive traits of chickens from the gene pool are characterized with high egg fertility - from 96.56% for Line NG t? 86.98% of Plymouth Rock Line G. Among the egg-type chicken lines, the highest hatchability rate from fertile eggs was observed in Line D - 89.05%. Chickens of all lines studied exhibited low death rates. The highest egg mass was that of chickens from Line G - 63.10 g and Line ? - 61.73 g The highest egg production over the 180-day period was that of the egg-type Line ? - 146 eggs, and Line ?Z-80 B - 145.67. [ABSTRACT FROM AUTHOR]

The experiment was performed in the Poultry Breeding Unit at the Institute of Agriculture, Stara Zagora, in 2009-2010. Three different chicken genotypes obtained by a specific plan were used: line R and line T from the Rhode Island Red breed and line N from the Rhode Island White breed. For each line, 20 selection nests with 12 hens and 2 cockerels (one principal and one spare) were formed. On the basis of observed zootechnological parameters, the line T was found to be superior to the other two lines with the highest live body weight of hens and cockerels and the lowest feed consumption per egg. Line N exhibited the highest hen-housed egg production rate, the intensity of egg laying, the age of egg laying's start and hatchability. The fertility or eggs produced from this line was higher than that of Line N by 7.94%, whereas the hatchability of fertile eggs was by 2.19% higher than that of Line P. The egg mass for Line P and Line T with 60.90 g and 60.24 g (?< 0.01) was superior to Line N. [ABSTRACT FROM AUTHOR]

The experiment was performed in 2011 in the breeder farm of the Hybrid Poultry Centre at the Institute of agriculture - Stara Zagora in order to determine the effect of the different preincubation storage periods on hatchability traits of turkey eggs and the changes in egg components. Eggs from light layer (LL) line of turkeys at the age of 38 weeks used as maternal side for turkey-broilers production were used. They were divided into the following groups: eggs stored for 14, 10, and 4 days as well as fresh eggs (without storage). The storage of eggs took place in an egg storehouse with constant air temperature and humidity (17°C and 72%). The loss of weight during the storage increased as the storage duration prolonged (ᵖ<0.001). During incubation, the highest weight loss percentage was exhibited by eggs stored for 10 days (14.29%) that was statistically significantly (ᵖ<0.001) different from weight loss of fresh eggs. which lost weight. The highest fertility (92.42%) was noted in fresh eggs. A very high early embryonic death rate was observed in eggs stored for 14 days (13.63%). The hatchability of fertile eggs was the highest in fresh eggs (90.77%) and the lowest in eggs stored for 14 days (71.45%) (ᵖ<0.001). The albumen percentage of total egg weight was the highest in fresh eggs (59.09%). The albumen pH increased with the storage duration and was the highest in eggs stored for 14 days (9.25). Albumen's height decreased as storage duration became longer. For incubation to be use turkeys eggs from LL line stored at least time at 72% humidity and 17°C, because hatchability decreases with increasing duration of storage. [ABSTRACT FROM AUTHOR]