Influence of the reproductive season on the sperm production of the germline chimeras of drakes

Abstract

The reproductive potential of males is determined by the quality of sperm and is crucial for successful reproduction. The quality of the ejaculate is associated with many factors: species and breed-specific features of reproductive characteristics, age of drakes, climate, reproductive season, conditions of retention and feeding. Studies on sperm production are made on meat breeds; however, egg breeds have not been studied sufficiently; therefore, the purpose of this research was to study the effects of the reproductive season on the quality and quantity of sperma of Shaoxing (Shaoxing), Shan Partridge Duck (shanma) and their germline chimeras.

The research was conducted from March to June 2017 at the Zhejiang Generation Biological Science and Technology Co., Ltd. Laboratory of the Zhejiang Academy of Sciences Institute of Ducks. In Zhuji City, Zhejiang Province, in the southeast of China. The eggs of Shaoxing and Shan Partridge Duck were used to create chimera animals. The Shaoxing breed was used as a donor and had a recessive feature - a dark brown feather, the Shanma breed was a dominant feature – a white-brown feather and used as a recipient. Before the experiment, the spleen was accustomed to the technique of taking sperm for 15 days. Qualitative evaluation of fresh spermatozoa was carried out immediately after taking it. In the first place, the color of sperm seedlings, the presence of contamination by fecal masses and the homogeneity of the consistency were estimated. Samples, contaminated by fecal masses, were discarded. The assessment of sperm quality was carried out in accordance with the Instruction on artificial insemination.

For the experiment, 3 groups of spleens of the 7th-month-old drakes of Shaoxing, Shanma and their chimeras were formed for 6 animals in each group, where each group received a manual dorso-abdominal massage method used to collect semen. Animals conformed to the standard for breed by live weight and exterior. Sperm from the pedigree was obtained by massaging the lumbar spleen's back.

In March, the maximum average value of volume of ejaculate was splenic 3 groups with a significant difference compared with 1 (P < 0.01) and 2 (P < 0.05) groups. The average sperm concentration varied from 3.619 in group 1 to 4.060 bln / ml in the group. In April, the scabies of the 3 groups in comparison with 1 (P < 0.001) and 2 (P < 0.05) groups also had the maximum value of indicators of ejaculate volume. The concentration of spermatozoa varied from 3.67 (1 group) to 4.77 billion / ml (group 3), the average values of which were within the error.

In May, the sperm studied in all three groups had different tendencies in terms of changes in qualitative and quantitative indicators. The maximum average value of the volume of ejaculate was 3 group, but the probable difference between these groups was only in group 1 (P < 0.01). The average sperm concentration was in the range from 4.141 (group 1) to 4.914 bln / ml (group 3). The spleens of the first group observed sperm from clear-white to milky-white color of medium consistency. The sperm of the splenics of the second and third groups was characterized by milk-white or pearl-white color, and a cream-like consistency.

At the beginning of the study, the volume of ejaculate in the first group of spleens was the lowest (0.08 ± 0.014 ml) among the three groups (2 gp – 0.12, 3 gp – 0.18 ml). However, during the first month, group I tended to increase the average volume of sperm (0.12 and 0.14 ml), whereas groups 2 and 3 showed a peak period, followed by a decline (2 gp – 0.19, – 0.17, 3 g –0.26,–0.24 ml).

The variance analysis of our data suggests that the proportion of the impact of breed on the volume of ejaculate is 25%, and the reproductive season – 13%.

In the selection of 6 times a week in our studies, the concentration of spleen sperm was lower compared to the frequency of selection in a day in all three groups. The highest concentration of sperm was in group 1 – 4.141 × 109 / ml, in group 2 – 4.712 x 109 / ml, group 3 – 4.914 x 109 / ml.

Indicators of sperm production of the obtained germeline chimeras indicate that they are suitable for use in biotechnological procedures for the production of transgenic animals of this species.