Egg-laying features, weight and size of germinative duck chimeras eggs

Abstract

The consequences of chimerization and its possible influence on the productivity of chimera offspring remain poorly understood. The objects of research were ducks (Anas platyrhynchos) of the Shanma (Shan partridge duck) and Shaoxing breeds kept at the Zhuji Guowei Poultry Development Co, Ltd, P.R.China. The study was conducted in the poultry genetics laboratory of the Zhejiang Academy of Agricultural Sciences on a duck farm of Zhejiang Generation Biological Science and Technology Co., Ltd. (Zhejiang Province, PRC). To create chimeras of ducks, the method described by Aige-Gil, Simkiss, 1991; M.T. Tagirov, 2010 was used. Blastodiscs have been isolated from freshly hatched fertilized  eggs using a filter paper ring. Shanma duck embryos have been used as recipients, and Shaoxing duck embryos, homozygous for plumage color gene allele (wild type), have been used as donors. Busulfan (SigmaAldrich, United States) have been used as a chemical agent that suppresses a division of primary germ cells (PGC) of recipient embryos. A hole in an eggshell (window) of  recipients (Shanma breed) have been made between a blunt and sharp ends of eggs. (This reduced a distance between an injector and an embryo needle). The recipients havebeen incubated for 8–10 hours at a temperature of 38 °C. After recipient eggs incubation for 8 hours, the windows were opened in them. Busulfan was injected into the subgerminal cavity of the embryo with a micropipette (1.5–3 μl of liquid). After busulfan injection, the empty cavity was filled with culture medium (RPMI-1640) supplemented with antibiotics (ampicillin, streptomycin), the hole was closed by plastic wrap and adhesive tape. The eggs have been incubated at a reduced temperature (+32 °C) for 24 hours with the aim of prolong the duration of busulfan action on the PGC (primary germ cells). More than 50% of embryos have been died in the first 2–3 days (after an  incubation start). Head and neck disorders have been observed in the 1.2% of embryos. Busulfan injection  at a concentration of 300 ng per egg have been leads to 95.0–96.3% mortality of duck embryos, concentration of 150 ng per egg, a mortality rate of 33.3–75.3% have been observed, concentration to 75 ng led to 18.75–38.5% of embryonic mortality. Analysis of the age of puberty (laying of the first egg) indicates that the chimeras matured later. If in the control group the average age of puberty was 139 ± 9 days, in the group of chimeras - 148 ± 13 days. Thus, we can attest that in our experiment, the chimeras matured later than the control animals, which may be due to the effect of busulfan in the sterilization of recipient embryos. The average weight of ducks in the control group was lower, and the group itself was more consolidated. Thus, in the control ducks weighed 1422.40 ± 57.00 g, the chimeras 1608.80 ± 94.76 g. The advantage of live weight chimeras over the control group may be due to the fact that the control group consisted of recipients served by Shanma animals. Egg production of ducks for the entire study period was   87.5 ± 0.05 % (control) 79.5±0.12 % (busulfan). The weight of eggs of ducks of two groups for the entire period was 70.62±0.199 g (control) and 71.15±0.157 g (p˂0.001). The eggs morphometric parameters of the studied ducks groups were: the average values of egg length were 6.056±0.0564 cm (control) and 6.269±0.1341cm (busulfan); egg breadth were 4.520±0.0053 cm (control) and 4.529±0.004 cm (busulfan). There were no statistical intergroup differences in the morphometric parameters of the eggs of the studied groups. In fact, we obtained results similar to the previous ones, which concerned the egg production of daughters of drake chimeras.