Inter- and intra-rater reliability of linear scoring in warmblood breeding.

Comparative analysis of methods for assessing the breeding value of stud bulls

In the context of restructuring the dairy cattle breed composition in the Russian Federation and the ongoing Holsteinization of populations, an accurate assessment of the breeding value of stud bulls is a crucial task for effective selection. The BLUP (Best Linear Unbiased Prediction) method, while being the international standard, requires adaptation and comparative assessment with traditional methods in domestic practice. The aim of this study is to conduct a comparative assessment of Holstein bulls used in the Vologda Region population based on offspring quality, using the BLUP method and the traditional “daughter-peer” method. The study was carried out on data from 6,760 first-calf heifers sired by 283 bulls from 25 breeding farms in the Vologda Region. A mixed-type biometric model was used to predict breeding value (EBV) and calculate its reliability (R²). A comparative analysis of the methods was performed using correlation (r) and Spearman rank correlation analysis (ρ). The BLUP method assessed all 283 bulls, of which 115 were identified as improvers for milk yield, 60 as neutral, and 108 as deteriorators. Reliability of the estimate (R² ≥ 0.5) was obtained for 125 animals (44.2%). Only a few bulls simultaneously improved two traits, and none improved all three. The “daughter-peer” method allowed for the assessment of only 88 bulls (31.1%). A moderate positive correlation was found between the results of the two methods (r = 0.33–0.43; p < 0.001). The BLUP method demonstrates an advantage in terms of assessment coverage and provides a more accurate accounting of genetic and paratypic factors. However, for practical breeding, it is necessary to establish clear threshold values for assessment reliability (R²). The correlation identified between the methods confirms the overall consistency of the results, indicating the potential for implementing BLUP in the breeding system, provided that the criteria for bull selection based on prediction reliability are standardized.

Updated approaches to assessing breeding value in purebred arabian horses: evaluation of individual racing performance and sire progeny quality

Improving the methodology for assessing the breeding value of horses based on racing performance is a relevant task in modern horse breeding. The aim of the study was to develop such a system for purebred Arabian horses based on the results of racetrack trials. The research material consisted of records from 3,690 starts of 621 horses from 2020 to 2024. Two key indicators based on the placing and the category (complexity) of the race were used to characterize performance: the R2024 rating and the Adjusted Transformed Rank (ATR). Statistical analysis included the calculation of correlations, repeatability, heritability (h²), as well as the assessment of the breeding value (BV) of horses and sires based on progeny quality, with the calculation of Absolute (ABV) and Relative (RBV) breeding value indices. An extremely high correlation was established between the R2024 and ATR indicators (r = 0.98). The ATR indicator demonstrated higher predictive reliability: the repeatability coefficient of results from two to three years of age was 0.24 compared to 0.16 for R2024. The heritability of racing performance was moderate: 0.18 for two-year-olds and 0.40 for three-year-olds. Based on the calculation of breeding value, statistically significant “improver” and “deteriorator” sires were identified. The effectiveness of early evaluation was confirmed: horses with low results at two years of age maintained low productivity at three years. The developed system allows for an objective assessment of the racing qualities of horses and the breeding potential of sires. The ATR indicator has been recognized as more preferable for use in breeding practice due to its stability and high repeatability. For integration into the existing grading system, it is recommended to develop a scale for converting ATR values into standard grading scores, taking into account age characteristics.

Heat-load-dependent inbreeding depression for production traits in Italian Holstein cattle

The objective of this study was to test whether the negative effects of inbreeding on production traits varied according to the level of environmental load. Traits analyzed were milk, fat, and protein yields, and somatic cell score (SCS). Environmental conditions were described using temperature (TEMP), relative humidity (RH), and the temperature–humidity index (THI), each divided into five equally sized classes. For each trait, the environmental variable with the largest impact was used to evaluate inbreeding effects across its classes. Inbreeding was measured using pedigree (FPED), the diagonal of the genomic relationship matrix (FGRM), and runs of homozygosity (FROH). Genomic-based inbreeding measures resulted in larger estimated inbreeding effects, compared to pedigree measures, with FGRM and FROH showing similar results. RH most affected milk yield, with losses of ~ 600 g/day in the highest RH class. Inbreeding led to losses of ~ 100 g/day per 1% increase, with genomic measures scaled to match FPED. For milk yield, losses were ~ 20% greater under higher environmental stress. THI was the most impactful variable for fat yield, with losses of ~ 90 g/day in the highest THI category. Inbreeding-related losses increased in more stressful environments, with average reductions of 3 g/day per 1% inbreeding, reaching 4 g/day in the highest THI class. Protein yield and SCS were mainly influenced by TEMP, with losses of ~ 70 g/day of protein and increases of 0.06 SCS units. Inbreeding caused losses of ~ 3.5 g/day in protein yield and increases of ~ 0.006 SCS units per 1% inbreeding. For these two traits, the relationship between inbreeding effects and environmental stress was less clear. For milk and fat yields, there was a significant interaction between environmental and inbreeding effects, suggesting that inbreeding depression influences heat tolerance in dairy cows. For milk and fat yields, there was a significant interaction between environmental and inbreeding effects, indicating that environmental conditions modulate the expression of inbreeding depression. These findings suggest that inbreeding depression influences heat tolerance in dairy cows.

Evaluation of Intermethod Reliability Between Online and In-Person Fitness Assessments Among Physically Inactive Adults.

Utility of Bland-Altman Plot in the Assessment of Inter-observer Variability for Internal Quality Control in Semen Analysis: A Cross-sectional Study

In a low throughout laboratory, fresh semen is a useful sample for daily quality control and Bland-Altman plot is an easy and effective tool for monitoring internal quality control when there are two assessors, obviating the need for complex statistical tests.

Genetic Analysis of Biometric Traits in Moghani Sheep Breed