Selection Criteria In Breeding Programs Research Articles

Genetic study of stress assessed with infrared thermography during dressage competitions in the Pura Raza Español horse

Despite the fact that physiological parameters in dressage are important because of their close connection to human–horse accidents, performance and welfare, these parameters are only rarely included in horse breeding programs. In Spain, the Pura Raza Español horse (PRE) Breeding Program focuses mainly on the selection of horses for satisfactory dressage ability. Studying the genetic parameters of eye temperature (ET) using infrared thermography (IR) as an indicator of stress in horses could highlight the suitability of this parameter to be included as a selection criterion in the PRE Breeding Program. The aim of this study was to investigate the heritability of ET measured with IR in Young Horse Dressage tests (YHDT) from the Breeding Program. Accordingly, 343 PRE were measured during 3 YHDT final competitions held in Spain. From these animals, 1746 ET measurements were taken on 3 different moments during each competition: 3h before the competition (ET_B), just after the competition (<5min after the dressage exercise) (ET_JA), and 3h after the competition, when the animal was resting (ET_A). Moreover, 6 different dressage score records were taken for each animal during the competitions: walk, trot, canter, general impression, submission and total score. The genetic parameters were estimated using a Bayesian procedure. The environmental effects (Age, Stud, Trip, Training, Event-Year and Rider) that were statistically significant (p<0.05) for each temperature trait were used in the genetic models. The pedigree file included a total of 3350 PRE. The correlations between the ET and expected breeding values for dressage (EBV), as well as the coincidence between the animals’ genetic rankings by their EBV, were also studied. Heritabilities for temperature traits ranged from 0.14 (ET_JA) to 0.50 (ET_A), while heritabilities for performance traits ranged from 0.44 (walk) to 0.37 (submission) and repeatability ranged from 0.25 (ET_JA) to 0.79 (walk). The dressage EBV and the ET EBV just after exercise showed statistically significant correlations with r2=0.21. Finally, the range of matching animals was higher (from 17% to 40%) when the top 25% of the animals for both parameters was selected. Our findings indicate that the selection of the best animals for dressage performance would also involve selecting the animals with higher ET values, showing a higher level of physiological stress. Hence, despite selection using ET in horses is achievable, more evidence about its validity, sensitivity and specificity is still needed in order to include ET as an additional selection criteria in Breeding Programs.

Genetic erosion of diversity in cereals

Cereals play an important role in human nutrition. Consequently, one of the main goals in breeding is to obtain varieties with high genetic potential for yield. Modern agricultural production includes the expansion of intensive varieties over large areas that lead to narrow selection criteria in breeding programs. The consequence is a drastic reduction in the number of species and genotypes (genetic erosion), or harming biological diversity of local populations, and spontaneous relatives (biodiversity) in cereals. Based on detailed inventories of the territory of Montenegro and to some extent in Eastern Serbia, a endangerment of gene pool in cereals could be denoted. The reason for this is a transition to another type of agricultural production, changing land purposes, the presence of nursing homes, and use of intensive varieties. Old varieties and local populations represent the original genetic variability that could be used in breeding programs and organic production. It is therefore essential to take measures to preserve the genetic resources of cereals.

Transpiration effciency and its relationship with carbon isotope discrimination under well-watered and water-stressed conditions in Stylosanthes scabra

Stylosanthes scabra cv. Seca is a widely sown tropical pasture legume in northern Australia and has a high degree of drought resistance. Identification of traits contributing to the drought resistance of Seca may be valuable for use in breeding programs. Transpiration efficiency (TE) has been suggested as one such trait contributing to drought resistance. Carbon isotope discrimination (Δ) has been proposed for estimating TE indirectly in C3 plants. A glasshouse experiment was conducted using 8 accessions of S. scabra to identify whether Seca differs in TE from other accessions of S. scabra and to determine the relationship between TE and Δ under both well-watered and water-stressed treatments. Seca maintained the highest TE (lowest Δ) under both control and stress treatments, and leaf Δ was significantly and negatively correlated with TE under both control and stress conditions. A significant and negative relationship was found between Δ and dry matter production under stress treatment. The interaction between accession and watering treatment was not significant for either TE or Δ. We also found a signirficant agreement between the performance in the field and in the laboratory for these 8 accessions. These results indicate that TE could be one of the significant factors contributing to drought resistance of Seca. Furthermore, Δ and/or specific leaf area may be useful as selection criteria in breeding programs to identify the lines with high TE.