Seaward migration of pink salmon Oncorhynchus gorbuscha (Walbaum) fry in the Malaya Khuzi River (North-Eastern Sakhalin) in 2018

Counting pink salmon Oncorhynchus gorbuscha fry, migrating seaward in the Malaya Khuzi River (NorthEastern Sakhalin), revealed the total half-million stock of the migrants in 2018. Forming such generation from extremely poor parental stock, entered the river in 2017 had been possible due to a high survival rate in the course of incubation. Seaward migration was about 1.5 month long and finished 7–10 days earlier than in previous years. Major part of the fry stock emigrated during the I decade of June. Dense aggregations of ice on the seashores during the mass seaward migration could bring negative effects on survival of the fry. Migration occurred at night. Day time migration was observed in case of decreasing water transparency on flooding. The migrants in most cases did not have yolk sack residuals. Mean values of the body length and weight of the migrants did not exhibit extensive changes for the period of migration.

ISSR polymorphism of laying hens of broiler parental stock distinguished by rates of growth and productivity indicators

Searching for biomarkers of high productivity in chickens is currently one of the relevant tasks facing poultry farming. Thus, the research was aimed at studying genetic traits of laying hens. The hens belonged to parental stock of the «Arbor Acres Plus» hybrid cross and varied according to the productivity abilities. The study was carried out in 2018-2019 at the PRODO Tyumen Broiler factory located in Tyumen, Tyumen region on three groups of chickens numbering from 6000 to 6085 bird units. Raising and evaluation of laying hens were carried out in accordance with the «Arbor Acres Plus» guidelines and standards for breeding of the parental generation and the regulations for the technology of the parent stoсk management and bird weighing which were developed on the basis of those guidelines and standards and adopted at the factory. The practice of raising the «Arbor Acres Plus» hybrid cross revealed a distinct differentiation of laying hens by body weight during the growth period. There were distinguished fast-growing «large» individuals, «small» individuals and «medium» individuals occupying an intermediate position. At the beginning of the experiment, during the 18th week of age the average mass of «small» chickens was 106 g less than that of chickens from the «medium» group. The average mass of chickens from the «medium» group was 139 g less than the indications in the «large» group, and the differences between the «large» and the «small» hens amounted to 245 g. Such differences remained until the 35th week, and then they leveled out substantially. The differences between groups of chickens were observed also in egg production rates, which decreased with increasing the age of laying hens (by 31-33 weeks). The amount of eggs per layer per week averaged out at 71.1 % for “small” hens, 72.8 % for the «medium», and 74.4 % for the «large» ones. To assess the genetic polymorphism of chickens the ISSR-PCR method was applied. Seven primers were used to study the genetic polymorphism of laying hens: (AG)8G, (AG)8T, (CA)8G, (GT)8C, (AC)8T, (TC)8C, (TG)8A. The experimental groups of laying hens differed both in the frequencies of ISSR bands and in the average indicators of polymorphism. Higher parameters of the proportion of polymorphic bands (P), genetic diversity (h), apparent (ne) and effective number of alleles (na) were observed in the group of «large» laying hens, while the «medium» and «small» groups had lower rates and did not significantly differ in the level of polymorphism among themselves. Higher rates of ISSR polymorphism observed in the group of fast-growing («large») laying hens could be a marker of a higher level of genetic diversity in this group compared to chickens from the other two groups. The conducted studies showed that ISSR markers can be recommended as a simple tool for monitoring the genetic diversity of stocks of laying hens.

Influence of rearing course of chicken broiler parent stock on selected reproductive parameters

The aim of study was to analyse the rearing of the Ross 308 parental stock in the context of hatching results. The study was carried out in production conditions. The body weight of birds was monitored using the JOTAFAN automatic weighing system during whole rearing and production period. Reproductive indicators were determined based on the results of eggs fertilization and hatchability. There was found that the body weight during rearing and production was in line with the standards for this breed. Moreover obtained reproductive indicators (fertilization of eggs and hatchability of fertilized eggs were higher than 90% between 28 and 56 week of parental stock life) indicate that environmental and nutritional conditions were proper.

The influence of the housing system on selected production features of chickens of Ross 308 parent stock

The aim of the research was to analyse the effect of the housing system on selected reproductive traits of parental stock of Ross 308 meat chickens. The study was conducted on two flocks, one of which was kept in a chicken house on a concrete floor entirely covered with litter, and the second in a chicken house in which one-third of the floor was a plastic slated floor and the other two-thirds was a concrete floor covered with litter. During the 38-week laying period, an average of 179.7 eggs were obtained from laying hens kept in the chicken house with a litter floor, including 168.2 hatching eggs, and 187,4 and 175.6 eggs, respectively, from hens kept in the chicken house with a slatted/litter floor (differences not statistically confirmed). The housing system non-significantly influenced feed intake and the number of eggs laid depending on where they were laid (inside or outside the nest). In the litter system, eggs outside the nest accounted for 3.1% and in litter/slatted floor system 9.8% of the total number of eggs laid; the differences were statistically non-significant.

Shading of stock plants and the use of auxin in red pitaya cuttings

Although there has been a significant expansion of red pitaya cultivation in Brazil and other countries around the world, its cultivation requires scientific expertise to identify the plant production systems best suited to Brazilian soils and climate. Therefore, this study aimed to evaluate the effect of exogenous auxin and shading of the parental stock plants on the subsequent quality of red pitaya cuttings. The use of a commercial rooting auxin (with and without) and five shading levels on stock plants (full sun, 35, 50, 65 and 80% shading) were tested via four randomized blocks in a factorial 2x5 scheme with two plants per plot. After 90 days, the following vegetative characteristics were evaluated: length of the longest root (LR), root dry mass (RDM), root width (RW), shoot fresh weight (SFW) and shoot dry weight (SDW), total dry weight (TDW), number of axillary shoots (NAS), sum of the length of the axillary shoots (SLAS), and shoot:root ratio (SRR). We concluded that for the production of high quality plants, collecting cuttings from stock plants grown in full sun or 80% shade is recommended, eliminating the need to use commercial rooting auxin.

Survival of Kamchatka pink salmon as result of combined influence of density regulation and environmental factors

Dynamics of stock abundance and survival is similar for the pink salmon populations from East Kamchatka and West Kamchatka, obviously because of the same large-scale environmental factors influence, as the Pacific Decadal Oscillation (PDO) and the Western Pacific pattern (WP) that correlate significantly with the pink salmon populations indices for various stages of the life cycle. The survival measured as the recruits number per parental stock (R/S) has a non-linear dependence on this environmental indices described by parabolic equations. These dependencies are used in reproductive models, which simulate observed fluctuations of R/S with high accuracy. Note that these environmental factors influence on the pink salmon survival is opposite for its odd and even generations. For example, high PDO value in November is unfavorable for survival of the pink salmons in East Kamchatka in the first year of their life (incubation) but favorable for survival of the same population in the second year (marine feeding) - that’s why strong and weak year-classes of pink salmon are alternated. Both PDO and WP indices have quasi-biennial periodicity that is a bit longer than the 2-year alternation of the pink salmon generations, hence favorable environments change their correspondence with odd or even generations from time to time, on average in approximately every 8 years. Similar regularities are supposed for other salmon species, as West Kamchatka coho salmon.

Variation in fecundity in the lesser sandeel: implications for regional management

The number of eggs produced by a parental stock is central to fisheries advice on recruitment potential. However, stock based estimates of egg production may give a misleading index of recruitment potential in stocks containing several reproductively isolated populations. This paper examines the ability of length, condition and oocyte developmental stage to predict levels of potential fecundity in the sandeel, Ammodytes marinus, in three important fished areas in the North Sea. Our results indicate that regional variation in this relationship exists, with fecundity in central areas of the North Sea being higher than those found just off the north-east UK. Oocyte diameter was also found to have a significant effect on potential fecundity, suggesting a down-regulation of oocyte numbers arising from pre-ovulatory atresia, however, this effect was not apparent in every model tested. Our findings have relevance to the local sustainability of spawning components and thus the regional management of the North Sea sandeel stock.