Heterosis effect in hybrid laying hens

The new original egg laying lines T, P and N selected at the Institute of Agriculture - Stara Zagora were used. Hybrid Т♂ × Р♀, Р♂ × Т♀ crosses were obtained and used for paternal line. Thereafter, the following breeding schedule of paternal and maternal lines was applied: Group I - (Р♂×Т♀)♂ ×N♀; group ІІ - (Т♂×Р♀)♂ ×N♀; group ІІІ - Т♂×N♀; and group ІV - Р♂×N♀. 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♂×Р♀) ♂ ×N♀ (162.08 days of age) and Р♂×N♀ (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♂×N♀ hybrids - 142 eggs. The heterosis effect for egg production in hybrids was significant

Effect of sex-linked dwarf gene on exterior appearance, productive performance and egg characteristics in a colored broiler dam line

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

Economic efficiency of fattening on different genotypes of slow-growing and fast-growing broiler chickens

Abstract. In the present study six lines from the National Gene Pool (Bulgaria) were used, four of which – line NG (New Hampshire G), line E (Barred Plymouth Rock), line Ss (Sussex) and line F (NG x Red Rhode Island) as maternal forms in the crossing schedule and two sire lines, meat type – line L (White Plymouth Rock) and line M (Cornish), for production of slow-growing broilers. The effect of genotype on meat quality traits was studied with 5 groups of 150 unsexed day-old chicks from each genotype, and after the manifestation of sexual dimorphism – male and female chickens at 70 and 84 days of age. In valuation on revenues and costs of the fattening of the compared groups current prices at the time of the experiment were used. Cost of feed is determined according to the actual feed. In determining the economic efficiency of fattening, three variants of sales prices per kg of meat – 3.60 BGN/kg, 4.65 BGN/kg and 5.30 BGN/ kg have been analysed. The rate of profitability is a synthetic indicator for economic efficiency, calculated by the formula: NP = (Profitability / Production costs) * 100, %. Feed expenses for experimental group I were lowered by 22.8%, while in groups II, III, and IV- by 13.48%, 9.42% and 9.05%, respectively, compared to group V, which registered the highest consumption of feed in the amount of 5.52 BGN. The share of feed expenses in group I was 53.45% of total expenses, and in groups II, III, and IV group they were 59.88%, 56.30%, 57.50%, and 56.87%, respectively. The highest profits per the accepted sale prices were observed in group V- 10.71 BGN, 13.68 BGN and 15.52 BGN, respectively, followed by group IV with 8.56 BGN, 10.92 BGN, and 12.38 BGN, respectively. At a level of sale prices of 3.60 BGN/kg a positive value of profitability was registered for the fattening of chickens from group V – 16.03%. In all other groups, the profitability norm was negative. At a level of sale prices of 4.65 BGN/kg, the highest profitability was observed in the chickens of group V – 48.21%, followed by group IV – 25.37%, while the lowest cost efficiency was in group III – 4.24%. In the variant with a sale price of 5.30 BGN/kg, the profitability norm was the highest in group V – 68.14%, followed by group IV – 42.13% and group II – 40.98%, while the lowest level was in group III – 18.21%

Estimation of heterosis, direct and maternal additive effects from crossbreeding experiment involving two White Plymouth Rock lines of chickens

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

Carcass traits and meat quality of different slow growing and fast growing broiler chickens

Abstract. The experiment was conducted in the breeder farm of department Population genetics, reproduction and technologies of poultry and rabbits at the Agriculture Institute of Stara Zagora. Five lines from the National Gene Pool of Bulgaria: line Ss (Sussex), line E (Barred Plymouth Rock), line NG (New Hampshire), line F (NG x Red Rhode Island), line L (White Plymouth Rock) were used as maternal forms in the crossing schedule and line M (Cornish) as a paternal form for production of slow-growing broilers. The birds were grown to 84 days. Feeding was done with compound feeds according to the age: starter (1/14 days of age), grower (14/28 days of age), finisher (28/84 days of age). By the end of the experiment, slaughter analysis was performed with 3 female and 3 male broiler chickens per group with live weight corresponding to the average of each genotype. The live weight was determined, as well as the grill weight, the weights of cuts (breast, thighs, wings), edible offal (heart, liver, gizzard) and abdominal fat. On the basis of these data, the slaughter yield and body parts ratios were calculated. The data for the live body weights of birds at slaughtering indicated the highest values for group V – 4040g, followed by groups ІV and ІІ – 3271.67g and 3186.67g, respectively (p<0.05). There was a statistically significant difference between the sexes with superiority of male birds (p<0.001). In the other 3 groups, breast meat percentage ranged from 19.48 to 19.84%. The share of thighs from the grill was the greatest in slow-growing chickens from group II – 33.01%, followed by group І – 32.35%, group IV – 32.18%, and the lowest- in groups ІІІ and V (31.91% and 31.18%, respectively). The analysis of data exhibited a significant effect of the genotype on water content of breast meat (resp. Dry matter), with lower values in slow-growing birds from group III – 73.19% (p<0.05), whereas in the other groups it ranged between 73.44 and 73.62%. The dry matter higher percentage was associated with better lavor of meat. The analysis of the effect of genotype on meat protein content showed that protein content was the highest in the breast of slow-growing chickens from group III- 24.89% and lowest in the breast meat of conventional broilers from group V – 23.86% (p<0.05). In the other 3 groups, it ranged from 24.55 to 24.59%. The protein content of thighs was the lowest in slow-growing birds from group I- 19.49%, and the difference was the highest when compared to groups II and III, also slow-growing (p<0.05). With respect to the thigh fat content, it was the highest in slow-growing chickens from group IV (5.84%), followed by fast-growing from group V (5.33%) and the lowest- in slow-growing birds from group І – 4.12% (p<0.05). The analysis of data showed a statistically significant effect of the sex on water content (p<0.001), fat (p<0.001) and ash (p<0.01). In males, thigh meat contained water and ash and in females more fat. The interaction of genotype and sex effects were important for thigh meat fat content, with highest values in fast-growing females from group V – 5.98% and lowest in slowly growing males from group I – 3.88% (p<0.001). Weak but statistically significant interaction between both factors was found with respect to thigh protein and ash (p<0.05). The highest protein content was established in slow-growing females from group IV (19.81%), whereas thigh ash was with highest percentage in slow-growing males from group II (1.11%

Nanostructures by self-assembly of polyglycidol-derivatized lipids

In this work we report on the self-assembly of five non-phospholipid polyglycidol conjugates in aqueous solution. The polymers are composed of a linear polyglycidol chain (degrees of polymerization, DP, are in the 8–110 range) linked to a strongly hydrophobic lipid-mimetic residue. Their behavior in dilute aqueous solution is investigated by a combination of experimental techniques – UV-vis spectroscopy, static and dynamic light scattering, fluorescence measurements, conventional and cryogenic transmission electron microscopy, and small angle X-ray scattering. The polymers spontaneously self-associate above a certain critical concentration, which depends on polyglycidol DP and temperature. According to the thermodynamic data, the self-assembly is an enthalpically disfavored endothermic process, driven by positive entropy contribution. The polymers with polyglycidol DP of 23 and above form small core–corona micelles. The latter are parameterized and the experimental values are compared to those of micelles of the commercially available poly(ethylene glycol)-derivatized lipids and other related non-phospholipid poly(ethylene glycol) conjugates. The polymer of the lowest polyglycidol DP form lamellar structures of co-existing morphology – spherical vesicles and highly anisotropic, elongated bilayer flakes

Process chain for serial manufacture of 3D micro- and nano-scale structures

This paper presents a cost effective route for serial fabrication of 3D structures and the achievement of function and length scale integration (FLSI) in products. A complex 3D functional pattern was designed and then used to validate this route for serial manufacture of component that integrates micro and nano scale functional features. It employs a viable master-making process chain that integrates, innovatively compatible and at the same time complementary, structuring and replication technologies to fabricate Ni shims. The shims are then utilised for the hot embossing of structures incorporating different 2.5D and 3D length-scale features. The resulting 3D profiles at different stages of the process chain were investigated and the factors affecting its overall performance were analysed