Nucleus Breeding Research Articles

Genotype-by-environment interactions for the growth and survival of Litopenaeus vannamei under normal and low-salinity environments

Litopenaeus vannamei is the primary shrimp species farmed worldwide, as it can tolerate salinities ranging from near freshwater to hypersaline seawater. Inland shrimp farming in low-salinity waters expanded in the Americas and Asia following the domestication of L. vannamei and may be primed for further growth. Salinity is a key production parameter affecting the growth and survival of shrimp and varies between seasons and locations. This study aimed to compare the growth and survival rates of L. vannamei under normal (NS; 30–32 ppt) and low-salinity (LS; 10 ppt) environments and estimate genetic parameters and genotype-by-environment interactions (G x E) between growth or survival rates and salinity. Over approximately seven generations, 1028 full-sib shrimp families were evaluated for growth (ADG) and survival in a nucleus breeding center under NS and LS environments. Parental models were used for single and multi-environment trial (MET) analyses to estimate genetic parameters and G x E. Growth (ADG) (0.32 ± 0.05 g vs. 0.29 ± 0.05 g) and survival (82.6 ± 10.8 % vs. 72.2 ± 19.1 %) were significantly better under the NS versus LS environment, respectively. Heritability estimates were low for growth (0.04–0.14) and low to moderate for survival (0.09–0.23). Genetic correlations (rg) between salinity environments were strong (0.87 ± 0.07) for growth and moderate (0.66 ± 0.14) for survival, indicating weak G x E for growth and moderate G x E for survival.

Heritability and correlations for honey yield, handling ease, brood quantity, and traits related to resilience in a French honeybee population

There is growing interest in selective breeding of the honeybee, resulting in the emergence of new breeding projects, often with an emphasis on improving resilience traits, in particular toward brood diseases. Lately, feed autonomy is also gaining importance. Here, we use data from a small breeding nucleus in France to estimate genetic parameters for common bee breeding traits and a novel trait reflecting honey reserves in the brood chamber. Open-mated queens were produced each year from inseminated dams between 2019 and 2021, and ~330 colonies were phenotyped each following year at three periods during the entire beekeeping season. Genetic parameters were estimated using ReML with an animal model. Narrow-sense heritability estimates ranged from low (around 0.15) for calmness and total capped brood surface both measured in early summer, to moderate (0.30 to 0.40) for hygienic behavior in spring, honey yield, and phoretic V. destructor load in early summer. Honey reserves in the brood chamber showed an intermediate heritability throughout the season (around 0.25). Gentleness had a null heritability. Most correlations between phenotypes adjusted for environmental fixed effects were close to zero. Among exceptions, there were honey reserves in the brood chamber in early summer with honey yield (around −0.2) and with the total capped brood surface in early summer (around −0.3). These estimates, although uncertain due to the dataset size, suggest that selection for production and resilience will be effective, even though simultaneous selection for honey yield and feed reserves might be difficult due to a possible genetic antagonism between both traits.

Validation of the Indigenous Technical Knowledge of Cattle Pastoralists of Andhra Pradesh and Telangana, India

Indigenous technical knowledge (ITK) of livestock breeding is often tacit and not necessarily expressed in conventional forms of scientific research and documentation. Indigenous livestock breeding systems rely mostly on qualitative traits than pure quantitative qualities. Qualitative traits are difficult to measure and most of the indigenous knowledge systems are in forms of qualitative traits. The lack of documentation and predominant qualitative nature makes it difficult to validate the ITK related to livestock breeding. In this context a study was conducted to examine the traditional breeding practices associated with two heritage cattle breeds of the Deccan Plateau region of India. The study examines the criteria used for selection of the breeding bulls of the indigenous Poda Thurpu and Nallmala-Pasa/Kamma, cattle breeds native to the study area. Results of the study identifies fourteen traits specific to breeding bulls and four traits that are generic to the breeding stock/cows. These traits/characteristics are ‘deemed desirable’ by the local cattle breeders for the ‘heritage breeds’, believed to have been bred and managed by them for generations. Observations of the present study supports the notion that traditional breeders of heritage breeds lay more emphasis on qualitative traits (ability to warding-off predators, fending off-springs, coat colour and texture, gait of the animal, temperament, and response and obedience to instructions of the master) than quantitative traits. It was found that local breeders give significant importance to the fertility of bovine bulls than cows. Breeding bulls are meticulously chosen with extreme caution and care, following a very long and meticulous selection process that could last for four years. Traditionally local cattle breeders of the study follow open nucleus breeding system for breeding and are strictly against promotion of inbreeding among their cattle herds. Only men are involved in cattle breeding in the study area and women usually stay away.

IMPROVED SELECTION AND BREEDING PARAMETERS OF THE OBROSHYN GRAY BREED GROUP OF GEESE

The results of the improvement of the selection and genetic parameters of the goose population obtained by purebred linear breeding and geese with blood transfusion of the large gray breed (IV generation) of Obroshyn breeding are given. The research was conducted on geese of the Obroshyn gray breed group with the aim of increasing the selection and breeding nucleus of geese with high-performance indicators. As a result of the selection and breeding work carried out in 2022, the effectiveness of the introductory crossbreeding of Obroshyn gray geese with great gray geese was proven. Improvement of productive qualities of Obroshyn gray geese was achieved with the infusion of large gray breed blood (IV generation) and preservation of the main qualities of this breed group: good adaptability to local conditions of feeding and maintenance, exterior, quality of meat and feather and down raw materials. Productivity indicators of Obroshyn gray geese (I group) were: laying capacity – 38,4 pcs.; egg weight – 164,0 g; fertilization of eggs – 86,3 %; hatching of goslings – 76,4 %; live weight of geese at the age of 9 weeks - males 4310 g, females - 3800 g; preservation – 95,0 %. Obroshyn gray geese of the 4th generation obtained by transfusion of large gray breed blood (group II) were characterized by correspondingly higher indicators: in terms of laying by 3,1 %, however, fertilization was lower by 5,8 % and hatching was lower by 4.4%. The preservation of geese in this group was higher by 3,2 %, and the live weight at the age of 9 weeks was 4.4% higher in males and 3.2% higher in females. The geese of the II experimental group were superior to their peers from the I group in terms of meat quality, in terms of the weight of the uncut and cut carcass, and the yield of edible parts. Geese of experimental group II were also characterized by better meat productivity at the age of 9 weeks, in which the mass of pectoral muscles was 7.0% higher in males and 1,4 % higher in females, and the mass of thigh muscles was higher in males and females - by 4,0 and 4,8 %, respectively, than in geese of the I group. Geese of experimental group II were also characterized by better meat productivity at the age of 9 weeks, in which the mass of pectoral muscles was 7.0% higher in males and 1.4% higher in females, and the mass of thigh muscles was higher in males and females - by 4.0 and 4.8%, respectively, than in geese of the I group.

The genetics of resilience and its relationships with egg production traits and antibody traits in chickens

BackgroundResilience is the capacity of an animal to be minimally affected by disturbances or to rapidly return to its initial state before exposure to a disturbance. Resilient livestock are desired because of their improved health and increased economic profit. Genetic improvement of resilience may also lead to trade-offs with production traits. Recently, resilience indicators based on longitudinal data have been suggested, but they need further evaluation to determine whether they are indeed predictive of improved resilience, such as disease resilience. This study investigated different resilience indicators based on deviations between expected and observed egg production (EP) by exploring their genetic parameters, their possible trade-offs with production traits, and their relationships with antibody traits in chickens.MethodsEgg production in a nucleus breeding herd environment based on 1-week-, 2-week-, or 3-week-intervals of two purebred chicken lines, a white egg-laying (33,825 chickens) and a brown egg-laying line (34,397 chickens), were used to determine deviations between observed EP and expected average batch EP, and between observed EP and expected individual EP. These deviations were used to calculate three types of resilience indicators for two life periods of each individual: natural logarithm-transformed variance (ln(variance)), skewness, and lag-one autocorrelation (autocorrelation) of deviations from 25 to 83 weeks of age and from 83 weeks of age to end of life. Then, we estimated their genetic correlations with EP traits and with two antibody traits.ResultsThe most promising resilience indicators were those based on 1-week-intervals, as they had the highest heritability estimates (0.02–0.12) and high genetic correlations (above 0.60) with the same resilience indicators based on longer intervals. The three types of resilience indicators differed genetically from each other, which indicates that they possibly capture different aspects of resilience. Genetic correlations of the resilience indicator traits based on 1-week-intervals with EP traits were favorable or zero, which means that trade-off effects were marginal. The resilience indicator traits based on 1-week-intervals also showed no genetic correlations with the antibody traits, which suggests that they are not informative for improved immunity or vice versa in the nucleus environment.ConclusionsThis paper gives direction towards the evaluation and implementation of resilience indicators, i.e. to further investigate resilience indicator traits based on 1-week-intervals, in breeding programs for selecting genetically more resilient layer chickens.

Optimal open nucleus breeding system for long-term genetic gain in the Pacific white shrimp using genomic selection

The open nucleus breeding system (ONBS) has been widely employed in livestock breeding and has demonstrated a desirable genetic gain compared to the traditional closed nucleus breeding system (CNBS). However, no related study and application for ONBS exist on aquatic animal breeding. The present investigation simulates the family-based ONBS with different proportions of introduced multiplier individuals used as parents of the nucleus population (NP) and CNBS schemes for the harvest body weight of the Pacific white shrimp (Litopenaeus vannamei). The multiplier population (MP) comprised progenies from eight families with high estimated breeding value (EBV) or genomic EBV (GEBV) of NP of the previous generation. ONBS was assigned three proportions (10%, 30%, and 50%) of the introduced MP individuals. The short-term selection (G0 to G10) and long-term selection (G0 to G20) were performed for CNBS and ONBS schemes using pedigree-based best linear unbiased prediction (PBLUP) with the A relationship matrix from the pedigree or single-step genomic BLUP (ssGBLUP) with the H relationship matrix integrating SNP markers and pedigree. The genetic gain of body weight and inbreeding coefficient of NP for eight breeding schemes with CNBS_PBLUP (CP), CNBS_ssGLUP (CS), ONBS_PBLUP (OP10, OP30, OP50), and ONBS_ssGBLUP (OS10, OS30, OS50) with three proportions of the introduced MP individuals were calculated. Compared to CP, genetic gains for the three OP schemes increased by 7.68 to 11.27% after short-term selection, and by 2.51 to 5.79% after long-term selection. In comparison to CS, genetic gains for the three OS schemes increased by 8.21 to 8.96% after short-term selection, and from 4.46 to 5.87% after long-term selection. The ONBS schemes achieved higher genetic gains than the corresponding CNBS schemes whether using genomic or pedigree information. The advantage of ONBS over CNBS is reduced after long-term selection. Genetic gains for the three OS schemes increased by 9.77 to 14.06% after long-term selection compared with the corresponding OP schemes. Furthermore, no significant difference (P > 0.05) in genetic gain was revealed among the ONBS schemes after either pedigree-based or genomic selection. Inbreeding coefficients for the three OP schemes increased from 59.45 to 70.98% compared with CP, whereas inbreeding coefficients for the three OS schemes increased from 24.72 to 32.22% compared with CS. Besides, after long-term selection, inbreeding coefficients for the three OS schemes decreased from 13.13 to 14.79% compared with the corresponding OP schemes. In a nutshell, ONBS using introduced MP individuals has great promise in the selective breeding program of L. vannamei. Genomic information has more potential to improve selection response and control inbreeding level than pedigree information when applying ONBS.

Modelling the lactation curve in Alpine × Beetal crossbred dairy goats using random regression models fitted with Legendre polynomial and B-spline functions.

The current study sought to genetically assess the lactation curve of Alpine × Beetal crossbred goats through the application of random regression models (RRM). The objective was to estimate genetic parameters of the first lactation test-day milk yield (TDMY) for devising a practical breeding strategy within the nucleus breeding programme. In order to model variations in lactation curves, 25,998 TDMY records were used in this study. For the purpose of estimating genetic parameters, orthogonal Legendre polynomials (LEG) and B-splines (BS) were examined in order to generate suitable and parsimonious models. A single-trait RRM technique was used for the analysis. The average first lactation TDMY was 1.22 ± 0.03 kg and peak yield (1.35 ± 0.02 kg) was achieved around the 7th test day (TD). The present investigation has demonstrated the superiority of the B-spline model for the genetic evaluation of Alpine × Beetal dairy goats. The optimal random regression model was identified as a quadratic B-spline function, characterized by six knots to represent the central trend. This model effectively captured the patterns of additive genetic influences, animal-specific permanent environmental effects (c2 ) and 22 distinct classes of (heterogeneous) residual variance. Additive variances and heritability (h2 ) estimates were lower in the early lactation, however, moderate across most parts of the lactation studied, ranging from 0.09 ± 0.04 to 0.33 ± 0.06. The moderate heritability estimates indicate the potential for selection using favourable combinations of test days throughout the lactation period. It was also observed that a high proportion of total variance was attributed to the animal's permanent environment. Positive genetic correlations were observed for adjacent TDMY values, while the correlations became less pronounced for more distant TDMY values. Considering better fitting of the lactation curve, the use of B-spline functions for genetic evaluation of Alpine × Beetal goats using RRM is recommended.

124 Disease Resilience Indicators Based on Phagocytosis Assays on Blood from Young Healthy Pigs

Abstract Infectious diseases impact the swine industry through increased morbidity and mortality, leading to large economic losses and reduced animal welfare. Disease resilience is the ability of an animal to maintain production performance under pathogen exposure and has gained traction as an approach to help reduce the impact of infectious disease. For this purpose, a wean-to-finish polymicrobial natural disease challenge model was set up, in which, using a continuous flow system, batches of 60 or 75 young healthy Landrace × Yorkshire barrows from one of seven breeding companies of PigGen Canada were entered into a quarantine nursery before their entry in a nursery/finisher that was seeded with multiple pathogens. The objective of this study was to evaluate phagocytosis assays that can be conducted on blood from young healthy pigs as potential indicator traits to select for disease resilience in high-health nucleus breeding herds. Immune cell proportions and their phagocytic activity were evaluated in blood collected at ~26 days of age in the quarantine nursery on 985 pigs. Genetic parameters, including heritabilities and genetic correlations with disease resilience phenotypes collected on these pigs and an additional 2,220 pigs from the same companies in the polymicrobial challenge were estimated using GBLUP in ASReml 4.2, with the fixed effect of batch, the covariate of entry age, and random effects of pen by batch, litter, and additive genetics, using a genomic relationship matrix derived from genotypes of 650K single nucleotide polymorphisms. Results showed moderate heritability estimates for immune cell proportions (average = 0.36; range = 0.22-0.42) and the % of phagocytizing cells for each cell type (0.32; 0.19-0.48), but low estimates for mean fluorescence intensity (MFI) of the phagocytizing cells of each type (0.2; 0.05-0.3). Estimates of genetic correlations with disease resilience traits ranged from -0.93 to 0.72, but had substantial standard errors. Granulocyte % had a high positive genetic correlation with number of health treatments across the challenge nursery and finisher (0.72 ± 0.5), while a greater % phagocytizing eosinophils was genetically correlated with decreased growth rate in the challenge nursery (-0.26 ± 0.2) but greater growth rate (0.33 ± 0.2) and reduced mortality in the finisher (-0.78 ± 0.6) and across the challenge nursery and finisher (-0.50 ± 0.4). Greater MFI of phagocytizing eosinophils was also genetically correlated with reduced mortality across the challenge nursery and finisher (-0.93 ± 0.5). These results provide insights into potential indicator traits that can be used to select for disease resilience without the need to subject animals to disease, with the overall aim to improve animal welfare and increase production performance in herds that are subject to hard-to-manage infectious pathogens. This project was supported by Genome Canada, Genome Alberta, PigGen Canada, and USDA-NIFA grant #2017-67007-26144.

Cytogenetic screening of a Canadian swine breeding nucleus using a newly developed karyotyping method named oligo-banding

BackgroundThe frequency of chromosomal rearrangements in Canadian breeding boars has been estimated at 0.91 to 1.64%. These abnormalities are widely recognized as a potential cause of subfertility in livestock production. Since artificial insemination is practiced in almost all intensive pig production systems, the use of elite boars carrying cytogenetic defects that have an impact on fertility can lead to major economic losses. To avoid keeping subfertile boars in artificial insemination centres and spreading chromosomal defects within populations, cytogenetic screening of boars is crucial. Different techniques are used for this purpose, but several issues are frequently encountered, i.e. environmental factors can influence the quality of results, the lack of genomic information outputted by these techniques, and the need for prior cytogenetic skills. The aim of this study was to develop a new pig karyotyping method based on fluorescent banding patterns.ResultsThe use of 207,847 specific oligonucleotides generated 96 fluorescent bands that are distributed across the 18 autosomes and the sex chromosomes. Tested alongside conventional G-banding, this oligo-banding method allowed us to identify four chromosomal translocations and a rare unbalanced chromosomal rearrangement that was not detected by conventional banding. In addition, this method allowed us to investigate chromosomal imbalance in spermatozoa.ConclusionsThe use of oligo-banding was found to be appropriate for detecting chromosomal aberrations in a Canadian pig nucleus and its convenient design and use make it an interesting tool for livestock karyotyping and cytogenetic studies.

Идентификация SNP, ассоциированных с воспроизводительной способностью крупного рогатого скота

The problem of reproduction of cattle in the Russian Federation remains relevant from year to year and is characterized by a rather low yield of offspring per 100 queens, which causes significant economic damage. The solution to this problem is associated with an increase in the efficiency of the implementation of the genetically determined reproductive capabilities of animals. Scientific novelty lies in the study of molecular genetic mechanisms of cattle fertility control. The aim of the work was to identify allelic variants of SNPs associated with the reproductive ability of cattle. Whole genome genotyping was performed. Research methods. The studies were carried out on cows of the Holsteinized Black-and-White breed of the Ural type. The genetic profile of Black-and-White animals has been studied, SNP significantly associated with the reproductive qualities of cows have been identified, genetic variants and combinations of DNA markers have been identified that improve the reproductive qualities of cows. Results. In terms of reproduction indicators (multiplicity of insemination, duration of the service period), it was found that the multiplicity of insemination for animals with the genotype ARS-BFGL-NGS-71623GG was 1.33, which is lower compared to the genotypes ARS-BFGL-NGS-71623AA and ARS-BFGL- NGS-71623AG by 0.27 and 0.5 units. Heifers with the ARS-BFGL-NGS-85003AC genotype are inseminated at an earlier age than other animals. A significant difference in live weight at the first insemination was noted only for the ARS-BFGL-NGS-71623 gene. It is recommended to select animals with homozygous genotype ARS-BFGL-NGS-71623GG to improve the reproductive ability of cows in the breeding nucleus.

Changes in genetic diversity of Asian seabass in a 20-year breeding program

Asian seabass (Lates calcarifer) has become a popular aquaculture species. In Singapore, a breeding program of Asian seabass started with 549 brooders in 2004. In the past 20-years, selection within families in each of 105 mass crosses was conducted with the assistance of molecular parentage using DNA markers. Growth, resistance to diseases, and omega-3 content of Asian seabass were improved. In this study, the genetic diversity in breeding nuclei from the founder broodstock (F0) to the fourth selected generation (F4) was estimated using 10 neutral microsatellites. In F0, F1, F2, F3, and F4, the expected and observed heterozygosity were largely maintained, and inbreeding indices were near zero. These data indicate that selection within families in mass–crosses between genetically distantly related broodstocks can avoid inbreeding. The average allele number (A) and effective population size (Ne) decreased from 10.0 to 7.1, and from 79.6 to 30.1 in F0 and in F4. The reasons for the reduction of A and Ne might be the non-contribution, and unequal contribution of broodstock to offspring and/or bottlenecks. Therefore, we recommend introducing some new Asian seabass genetic material to the breeding nucleus and improving the reproductive performance of brooders. Our study provides a better understanding of the changes in genetic diversity in an Asian seabass breeding program and highlights the importance of monitoring genetic diversity in different generations in a breeding program.

Fatty Acid Profiles and Nutritional Indices/Ratios of Colostrum and Transient Milk from Landrace, Large White, and Landrace × Large White Crossbred Sows

Fatty acid (FA) profiles are needed to assess the nutritional quality of sow colostrum and transient milk that may be used in developing milk replacer diets for piglets and their possible use as a functional food or nutraceutical. This study analyzed the FA profiles and compared the FA-based nutritional indices/ratios of colostrum and transient milk from Landrace, Large White, and Landrace × Large White crossbred sows in a swine nucleus breeding farm in the Philippines. Colostrum and transient milk samples were collected by hand within 24 h after parturition and 36–72 h after farrowing, respectively; immediately frozen at –20 °C until analyzed for FA composition by gas chromatography. Among the major FAs with the highest proportions, palmitic acid (C16:0) and linoleic acid LA (C18:2 n-6) were higher in colostrum (20.7% and 25.0%, respectively) than in transient milk (18.7% and 18.8%, respectively). Oleic acid (C18:1 n9c) was higher in transient milk (34.9%) than in colostrum (32.2%). The polyunsaturated FA (PUFA) to saturated FA (SFA) ratio was higher in sow colostrum (0.81:1) than transient milk (0.65:1). However, transient milk had better linoleic acid to α-linolenic acid C18:3 n-3 (LA/ALA) ratio, more balanced omega-6 to omega-3 (n-6/n-3) ratio, slightly lower atherogenicity index (IA= 0.43 vs 0.46) and thrombogenicity index (IT= 0.81 vs 0.85), higher health-promoting index (HPI= 2.33 vs 2.16), and higher hypocholesterolemic/ hypercholesterolemic ratio (h/H= 2.66:1 vs 2.55:1) than colostrum. Both colostrum and transient milk from Large White sows had lower IA and IT values and higher PUFA/SFA ratio, HPI, and h/H ratio compared to Landrace sows. Crossbred sows had colostrum and transient milk with lower average IT than purebred sows. The PUFA/SFA ratio, HPI, and h/H ratio in colostrum were also higher for crossbred sows than for purebred sows. In conclusion, colostrum from crossbred sows may be used in the preparation of milk replacer formulations for piglets, while transient milk, especially from Large White sows, may be considered in the development of sow milk - based supplements in the human diet.

ЭФФЕКТ СЕЛЕКЦИИ ПРИ МАССОВОМ ОТБОРЕ КОРОВ-ПЕРВОТЁЛОК ПО МОЛОЧНОЙ ПРОДУКТИВНОСТИ

The paper discusses milk production in a black-and-white herd. The study focuses on the lines the animals belong to and calculates the main breeding and genetic parameters of the herd within the lines and the whole livestock. For a nucleus breeding scheme, cows are selected from highly productive lines with the highest heritability indices. The study has revealed an option to improve the selection efficiency for the studied trait. When selecting cows that have the best milk yields from the lines with high heritability indices for the breeding scheme, the study has established genetic progress in such indices as milk yield and fat content. When selecting 50 % of cows for the breeding scheme, genetic progress is significantly higher than when selecting 70 % of cows.

Does the Release of Bonelli’s Eagles from Captive Breeding Nucleus Contribute to Population Rehabilitation?

During the late 1960s, the Bonelli’s Eagle (Aquila fasciata) population in Israel was brought to the brink of extinction, due to a combination of factors. A rehabilitation program set in 2000 included few measures, among them the release of eaglets from a captive breeding nucleus, producing two to seven eaglets yearly. In recent years there is an apparent increase in the number of Bonelli’s Eagle pairs breeding in the wild, including the reoccupation of territories that were abandoned for many years. Yet, there is only little evidence for the recruitment of captive-born eagles into the wild population, and their contribution to its growth is unclear. These subjects are now being examined by a telemetry study, comparing dispersal patterns and survival rates of captive versus nature hatched eagles. The results from the first five years of study show significant differences between these two groups, with captive hatched eagles dispersing much farther away from their natal site compared to the dispersal of wild eagles. The different dispersal patterns may be the reason for the lower survival rates exhibited by the captive hatched eagles, as many of them wander to neighboring countries where they are subjected to shooting and trapping. Moreover, these birds also have a higher tendency to being electrocuted on power lines. Genetic analysis and alteration of the releasing methods are being used in order to check whether the different movement and behavior attributes of the captive-hatched eagles are linked to genetic properties or behaviorally mechanisms during their growth.

Additive and Dominance Effects of MC4R and PIT1 Polymorphisms on Production and Carcass Traits in Duroc Pigs

This study aimed to estimate the allelic and genotypic frequencies of single nucleotide polymorphisms (SNPs) of MC4R (melanocortin-4-receptor gene) and PIT1 (pituitary specific transcription factor-1) genes, and their additive dominance genetic effects on production and carcass traits in Duroc pigs. A total of 2170 tail tissue samples (1728 gilts and 442 male pigs) were collected from Dabaco Nucleus Breeding Pig Company, Bac Ninh province, Vietnam from January 2017 to June 2020. Polymorphisms in the MC4R and PIT1 genes were detected using the PCR-RFLP method. For MC4R, the frequencies of alleles A and G were 0.430 and 0.570, respectively. For PIT1, the frequencies of alleles A and B were 0.460 and 0.540, respectively. The genotype frequency distribution of the MC4R gene was in Hardy-Weinberg equilibrium (P = 0.375), but the genotype frequency distribution of PIT1 (P <0.001) was not. The MC4R and PIT1 polymorphisms were significantly associated with final body weight and average daily gain (P <0.001). Significant additive effects were also found (P <0.05) for the two traits. The selection of individuals with the MC4R genotype AA and PIT1 genotype AA could improve final body weight and average daily gain in Duroc pigs.

The microstructural evolution, mechanical and dielectric properties of BNW/SiO2 ceramics

The boron nitride reinforced fused silica (BN/SiO2) ceramics are excellent high-temperature wave-transparent candidates, but encumbered by the unsatisfactory reliability and economy until now. Herein, promising BN whisker reinforced SiO2 (BNW/SiO2) ceramics are fabricated via hot-pressing, aiming to provide fundamental insight into their microstructural evolution, mechanical and dielectric properties. The densification behaviour and microstructural evolution are characterized by step-testing the sintering temperature and the BNW content, determining that SiO2 matrix undergoes crystal nucleus breeding (≤1300 °C), followed by nucleation and growth (＞1300 °C), and BNW presents a uniform and stable structure (≤1350 °C) and skin-core structure (1450 °C), respectively. The underlying strengthening and toughening mechanisms are elucidated through constructing a multilevel porosity dependence of mechanical behaviour associated with the BNW content. Compared with 5 wt. % BNW/SiO2 ceramic sintered at 1350 °C (S5-1350), the lightweight 20 wt. % BNW/SiO2 ceramic sintered at 1300 °C (S20-1300) exhibits 619.1% higher machinability parameter while maintaining the mechanical properties. Moreover, the lightweight S20-1300 possesses a low dielectric constant (ε) of 3.77, loss tangent (tan δ) of 1.25 × 10-3 and coefficient of thermal expansion (CTE) of 1.34 × 10-6 K-1. The insights obtained from this study would help to advance the application of BN/SiO2 ceramics in high-temperature radome.

Bayesian evaluation of the effect of non-genetic factors on the phenomics for quality-related milk nutrients and yield in Murciano-Granadina goats.

The aim of this study was to evaluate the effect of non-genetic factors on the variability of milk production and composition using Bayesian linear regression. We analyzed 2594 milk records from 159 dairy goats from the breeding nucleus of the Murciano-Granadina breed. Bayesian linear regression was used to determine the effects of non-genetic factors on the phenomics for quality-related milk nutrients and yield. Multivariate regression model significantly explained 21.5%, 40.0%, 41.5%, 44.3%, 44.6%, and 47.5% of the variability in somatic cell count (SCC, sc/mL), lactose (%), protein (%), milk yield (kg), fat (%), and dry matter (%), respectively. Although the aforementioned factor combination significantly conditions milk production and composition, SCC may be particularly affected by collateral factors. Milking routine and drying period factors are reference predictors to be considered in the evaluation of milk production and composition progression. Drying period extensions positively repercussed on milk yield and lactose content, but negatively affected fat, protein, dry matter contents, and somatic cell count. Variability across drying years may depend on the drying season rather than the drying month course, except for milk yield, for which an increasing trend was reported from winter to summer. Including drying period-related non-genetic factors in genetic evaluations improves the accuracy of the regression models and permits to boost the commercial possibilities and profitability of local breeds.

NON-SPECIFIC HETEROSIS ON A COMPLEX OF FEATURES OF ADAPTABILITY ON THE EXAMPLE OF MINI-PIGS

The authors studied the genetic diversity of the reproductive nucleus of mini-pigs at the Institute of Cytology and Genetics (IC&G) of the Siberian Branch of the Russian Academy of Sciences (SB RAS). To do this, the authors used the indicators of individual homo- and heterozygosity, calculated based on the «blood fractions» of large and small forms of domestic pigs, initial for the breeding group. The study showed that the average value of individual heterozygosity (conditionally actual) is 0.800±0.004, while homozygosity for the contribution of large and small forms of the domestic pig is 0.020±0.002 and 0.180±0.010, respectively. The indicator «blood fraction» can have two interpretations: 1) the probability of transmission of the ancestral allele in several generations; 2) the proportion of the genome of the ancestor that is present in the descendant. The authors determined their frequencies, which turned out to be 0.424 and 0.576 as if assuming the presence of a hypothetical locus with different alleles in the large and small forms of the domestic pig (respectively Ak and Am). The authors calculated heterozygosity for the breeding nucleus based on these frequencies while respecting the Hardy-Weinberg law. As a result, it turned out that the unbiased value is 0.493±0.067, which is significantly (P<0.001) less than the observed conditional-actual value. Selection is carried out according to a set of signs of general fitness (state of health, reproductive qualities, the viability of offspring, etc.) during the formation of the reproductive core of the breeding group of mini-pigs of the IC&G SB RAS. Therefore, the authors concluded that the increased heterozygosity of the breeding stock is due to the preferential selection of heterozygotes. But since selection is carried out according to a set of signs of general fitness, it can be stated that in the reproductive core of the selection group there is an effect of nonspecific heterosis due to heterozygosity. As a result, selection into the reproductive nucleus of individuals with high values of individual heterozygosity calculated by the proposed method can provide heterosis based on general adaptiveness.

High-throughput phenotyping by deep learning to include body shape in the breeding program of pacu (Piaractus mesopotamicus)

Deep learning (DL) is a cutting-edge technology that enables high-throughput phenotyping in aquaculture. The routine application of DL offers new opportunities for the genetic selection of appearance traits, especially those related to body shape. The criteria currently used for the trait selection of commercial interest, such as rapid growth and weight gain, can directly influence the animal's appearance, which is a criterion for sales and profit. Different morphotypes of the pacu Piaractus mesopotamicus (elliptical and rounded) have been described previously and may represent different commercial trends. Therefore, this study aimed to 1) develop a computer vision system (CVS) through deep learning that targets the prediction of morphometric measurements and body shape (morphotypes) in pacu, 2) analyze whether morphotypes vary according to the environment, sex, and/or age, and 3) estimate genetic parameters for body shape, using the condition factor (K) and ellipticity (E) as criteria. Data from 1380 individuals corresponding to 48 full-sib families were evaluated in two distinct environments (breeding nucleus: env1; commercial fish farm: env2). The animals were evaluated based on their weight and morphometric measurements at 15 and 28 months of age (growth stage). We used the mask R-CNN model as a deep-learning algorithm, which was optimized for a ResNet architecture with only 18 layers. This resulted in a faster training period (8GB NVIDIA 2060 RTX in less than a day), which requires less computational effort. The pacu CVS was effectively developed to account for the segmentation of several fish body regions (head, body, fins, and pelvis), as corroborated by the high correlations of measurements predicted manually and automatically. We detected K and E variation at different growth stages and environments, in which fish tend to have rounded shapes in env2 and at 28 months old. The body shape heritability indicates that this trait is under moderate genetic control and should respond to selection. In conclusion, this study established an efficient CVS for pacu that is resilient to field conditions, allowing high-throughput phenotyping for the routine assessment of body shape in breeding programs for this species.

Development and validation of a low-density SNP panel for paternity and kinship analysis and evaluation of genetic variability and structure of commercial Pacific white shrimp (Litopenaeus vannamei) populations from Brazil

Genetic improvement programs of the Pacific white shrimp (Litopenaeus vannamei) have been implemented worldwide aiming to enhance growth, survival and disease resistance traits. The use of low-density SNP panels for performing high-throughput, low-cost paternity assignments, kinship determination and evaluating genetic variability parameters and structure in L. vannamei broodstock lines will help increase observed genetic gains. Samples from four selection lines from a breeding nucleus (N = 167), from seven retail stores in Brazil (N = 191), and from families (offspring, known dams and putative sires) from a commercial breeding nucleus (N = 257) were used in the study. All samples were genotyped with a set of 96 SNP markers mined from a dataset developed locally. Observed minor allele frequencies for 88 quality-controlled SNPs ranged between 0.11 and 0.5 with an average of 0.38. Mean observed population heterozygosity varied from 0.319 to 0.471. Mean estimated population Fis was 0.022 and ranged from −0.075 to 0.109. STRUCTURE and PCA analysis revealed retail store samples to have a mean composition of 85% from a common population, suggesting a common post larvae producer supplied the different grow out farms and/or wholesale merchants from different sampled areas. Overall average estimated probabilities of non-exclusion considering one known parent and one putative parent was 1.1 × 10–6, 7.0 × 10–4 considering no known parents, and 2.6 × 10–10 considering a putative pair of sire and dam. Parentage analysis using CERVUS resulted in correct dam assignments of all tested offspring. Sire assignments with >95% confidence were obtained in all cases. Obtained results indicate the developed SNP panel provides a viable tool for performing large-scale high-throughput kinship and paternity assignments, and population structure and assignment of commercial Pacific white shrimp broodstock. The developed tool can provide pedigree information and improve genetic gains in breeding programs that seek to increase grow-out survival rates and overall productivity in biologically and non-biologically challenging production environments.