Fine-scale estimation of inbreeding rates, runs of homozygosity and genome-wide heterozygosity levels in the Mangalarga Marchador horse breed.

With the availability of high-density SNP panels and the establishment of approaches for characterizing homozygosity and heterozygosity sites, it is possible to access fine-scale information regarding genomes, providing more than just comparisons of different inbreeding coefficients. This is the first study that seeks to access such information for the Mangalarga Marchador (MM) horse breed on a genomic scale. To this end, we aimed to assess inbreeding levels using different coefficients, as well as to characterize homozygous and heterozygous runs in the population. Using Axiom ® Equine Genotyping Array-670k SNP (Thermo Fisher), 192 horses were genotyped. Our results showed different estimates: inbreeding from genomic coefficients (FROH ) = 0.16; pedigree-based (FPED ) = 0.008; and a method based on excess homozygosity (FHOM ) = 0.010. The correlations between the inbreeding coefficients were low to moderate, and some comparisons showed negative correlations, being practically null. In total, 85,295 runs of homozygosity (ROH) and 10,016 runs of heterozygosity (ROHet) were characterized for the 31 horse autosomal chromosomes. The class with the highest percentage of ROH was 0-2 Mbps, with 92.78% of the observations. In the ROHet results, only the 0-2 class presented observations, with chromosome 11 highlighted in a region with high genetic variability. Three regions from the ROHet analyses showed genes with known functions: tripartite motif-containing 37 (TRIM37), protein phosphatase, Mg2+ /Mn2+ dependent 1E (PPM1E) and carbonic anhydrase 10 (CA10). Therefore, our findings suggest moderate inbreeding, possibly attributed to breed formation, annulling possible recent inbreeding. Furthermore, regions with high variability in the MM genome were identified (ROHet), associated with the recent selection and important events in the development and performance of MM horses over generations.

Immediate Effect of Hoof Trimming on Hoof and Thoracic Joint Angles in Mangalarga Mares.

It is important to understand the effects of hoof trimming on hoof and limb conformation to maximize its benefits on the health of the appendicular skeleton of horses, thus promoting improvements in athletic performance and sporting longevity with regard to athletic horses. There is little information on possible changes in the angulation of the thoracic limb joints after hoof trimming and correlations between the angulation of the thoracic limb joints with hoof measurements. To that purpose, nineteen Mangalarga mares received routine hoof trimming. Visual recordings (photographs) were taken before and after the procedure. Differences (p < 0.05) were found in hoof length, toe angle, heel angle, medial heel height, and metacarpophalangeal angle. Before trimming, correlations were found between frog length and scapulohumeral angle (SH) (r = -0.457; p = 0.049), and between toe length and shoulder-ground angle (SG) (r = -0.553; p = 0.049). A correlation was also seen between the distance from the frog to the lateral wall and the SH angle (r = 0.690; p = 0.001). After trimming, there was a correlation between humeroradial (HR) and SH joint angles (r = 0.669; p = 0.002), and the SG and SH angles (r = 0.488; p = 0.034). This study showed an immediate effect of trimming on the toe angle and heel angle and on the metacarpophalangeal joint angle, in addition to correlations between the hoof and proximal joint angles, following trimming, thus evidencing the relevance of trimming not only in hoof morphology, but also in the conformation of the appendicular skeleton of horses.

Influence of Stretching Exercises, Warm-Up, or Cool-Down on the Physical Performance of Mangalarga Marchador Horses.

The Horse Agribusiness Complex is an important activity in the Brazilian agricultural sector. Mangalarga Marchador (MM) is the most numerous breed of horses in Brazil and its temperament and gait characteristics (4-beat stepping gait) allow for the constant growth of the breed and the performance of vs. equestrian activities. The training management currently adopted with MM horses is based on empiricism, and scientific support is necessary to improve the well-being of horses in competitions and maintain the physical integrity of these athletes. Therefore, this study aimed to verify the effects of stretching, warming up, and/or cooling down on their performance in marcha tests. 6 MM geldings (aged between 3 and 7 years and average weight of 400 kg) were used. The pre-experimental stage for the physical conditioning of the horses lasted 46 days. The experimental phase lasted 42 days and consisted of 6 marcha tests performed every 7 days. The experimental design was in a Latin square (6 × 6), in which each horse was submitted to the following exercise protocols: A) 50-min marcha test following the official regulations of the Brazilian Association of Horse Breeders Mangalarga Marchador (ABCCMM); B) 10 min of warm-up before marcha test; C) 10 min of cooling after marcha test; D) 10 min of warm-up before marcha and 10 min of cool-down after marcha test; E) 10 min of stretching before the marcha test; F) 10 min of stretching, 10 min of warm-up before and 10 min of cool-down after the test. Horses were evaluated before and after marcha tests for heart rate (HR), respiratory rate, rectal temperature, glucose, lactate, creatine kinase, aspartate aminotransferase and cortisol. Data were submitted to 2-way analysis of variance (exercise protocols and evaluation moments) and means were compared by Tukey's test (P≤0.05). The HR and blood lactate results indicated a beneficial effect of warm-up or stretching practices on the performance of Mangalarga Marchador horses submitted to simulated marcha tests in accordance with the official ABCCMM regulation and lasting 50 minutes.

Intense exercise and endurance-training program influence serum kinetics of muscle and cardiac biomarkers in dogs.

Few data exist on the physiological consequences of an incremental exercise test (IET) and training in dogs. Here we evaluated the effect of an endurance-training program (ETP) on the kinetics of the serum biomarkers: creatine kinase (CK), aspartate aminotransferase (AST), myoglobin, cardiac troponin I (cTnI), and creatine kinase isoenzyme MB (CK-MB). Eighteen Beagle dogs were assigned to three groups: sedentary (S), untrained (U), and trained (T). The dogs from the groups T and U underwent IET, and their lactate threshold (LT) was determined. The LT and velocity corresponding to the LT (VLT) was determined by visual inspection. The VLT was utilized to determine the training intensity level. Thus, the dogs from group T underwent an eight-week aerobic conditioning program with the intensity training set to 70-80% of the VLT. Next, dogs from the groups T and U have submitted to IET again. The group S did not undergo IETs or training. The maximal velocity (Vmax) at which the dog achieves in the IET and heart rate were determined. For biomarkers, venous blood samples were collected before the experimental procedure (baseline) and before and 1, 6, 12, 24, 48, and 72 h after the IETs. VLT and Vmax increased in group T (P < .05), indicating an improvement in dogs' aerobic and anaerobic fitness. CK and AST rose (P < .05), peaking 6 h after both IETs and returning to baseline levels after 12-24 h. Levels of cTnI and myoglobin were unaltered. CK-MB peaked 1 h after the IETs and returned to baseline levels after 12 h (P < .05). We concluded that ETP improved the aerobic capacity of the dogs without any skeletal or cardiac muscle injury.

Intense Exercise and Aerobic Conditioning Associated with Chromium or L-Carnitine Supplementation Modified the Fecal Microbiota of Fillies.

Recent studies performed in humans and rats have reported that exercise can alter the intestinal microbiota. Athletic horses perform intense exercise regularly, but studies characterizing horse microbiome during aerobic conditioning programs are still limited. Evidence has indicated that this microbial community is involved in the metabolic homeostasis of the host. Research on ergogenic substances using new sequencing technologies have been limited to the intestinal microbiota and there is a considerable demand for scientific studies that verify the effectiveness of these supplements in horses. L-carnitine and chromium are potentially ergogenic substances for athletic humans and horses since they are possibly able to modify the metabolism of carbohydrates and lipids. This study aimed to assess the impact of acute exercise and aerobic conditioning, associated either with L-carnitine or chromium supplementation, on the intestinal microbiota of fillies. Twelve "Mangalarga Marchador" fillies in the incipient fitness stage were distributed into four groups: control (no exercise), exercise, L-carnitine (10g/day) and chelated chromium (10mg/day). In order to investigate the impact of acute exercise or aerobic conditioning on fecal microbiota all fillies undergoing the conditioning program were analyzed as a separate treatment. The fillies underwent two incremental exercise tests before and after training on a treadmill for 42 days at 70-80% of the lactate threshold intensity. Fecal samples were obtained before and 48 h after acute exercise (incremental exercise test). Bacterial populations were characterized by sequencing the V4 region of the 16S rRNA gene using the MiSeq Illumina platform, and 5,224,389 sequences were obtained from 48 samples. The results showed that, overall, the two most abundant phyla were Firmicutes (50.22%) followed by Verrucomicrobia (15.13%). The taxa with the highest relative abundances were unclassified Clostridiales (17.06%) and "5 genus incertae sedis" from the phylum Verrucomicrobia (12.98%). There was a decrease in the phylum Chlamydiae and in the genus Mycobacterium after the second incremental exercise test. Intense exercise changed the community's structure and aerobic conditioning was associated with changes in the composition and structure of the intestinal bacterial population of fillies. The intra-group comparison showed that chromium or L-carnitine induced moderate changes in the fecal microbiota of fillies, but the microbiota did not differ from the control group, which was exercised with no supplementation. Fecal pH correlated positively with Simpson's index, while plasma pH correlated negatively. Our results show that exercise and aerobic conditioning can change in the microbiota and provide a basis for further studies enrolling a larger number of horses at different fitness levels to better understand the effects of exercise and training on the intestinal microbiota of horses.

Validation of a training protocol for marcha contests of the mangalarga marchador breed / Validação de um protocolo de treinamento para provas de marcha da raça mangalarga marchador

The Mangalarga Marchador breed is functionally evaluated through marcha contests. The present research aimed to verify the efficacy of a training protocol for conditioning Mangalarga Marchador horses for marcha contests. Eight mares were used in a completely randomized block split-plot design, where each animal was a block, the physical tests (T I, T II, T III, T IV and T V) every 21 days of training were the plots, and the time of evaluation and collection of samples inside each test were the split-plots. The mares were trained for 84 days for one hour a day, five days a week, with rest on Saturdays and Sundays. On Mondays, Wednesdays, and Fridays, the animals warmed up in an oval track by walking for 10 minutes and then marching for a period established individually through a marcha test. Next, the animals were led in walk gait until an hour of exercise was completed. On Tuesdays and Thursdays, the animals were trained outdoors for one hour only walking. The tests consisted of successive 10 minutes stages at marcha, which was interrupted when heart rate reached 150 beats per minute and lactate levels were greater than 4 mmol/L, or after 70 min of the test. Marcha duration, heart rate and blood concentrations of lactate were evaluated. The results were submitted to an analysis of variance and the averages were compared by Fisher's test at 5% probability. From zero at nine weeks of training, marcha duration increased progressively (p < 0.05), but there was no difference (p >0.05) between nine and 12 weeks of training. The training protocol used was appropriate to condition Mangalarga Marchador equines to compete in marcha contests following the rules of Brazilian Association of Mangalarga Marchador Breeders.

A raça Mangalarga Marchador é avaliada funcionalmente através das provas de marcha. O presente estudo objetivou verificar a eficácia de um protocolo de treinamento para condicionar equinos Mangalarga Marchador visando participação em provas de marcha. Foram utilizadas oito éguas em delineamento de blocos ao acaso com esquema de parcelas subdivididas, onde cada animal constituiu um bloco, as parcelas foram representadas pelos testes físicos (T I, T II, T III, T IV e T V) realizados a cada 21 dias do treinamento e as subparcelas foram constituídas pelos tempos de avaliação e coletas de amostras em cada teste. As éguas foram treinadas durante 84 dias, uma hora por dia, cinco dias por semana, com descanso aos sábados e domingos. Nas segundas, quartas e sextas-feiras, os animais realizavam 10 minutos de aquecimento ao passo em uma pista oval, em seguida marchavam por um tempo individual de marcha, estabelecido em um teste prévio. Depois, caminhavam até completar uma hora de exercício. Na terças e quintas-feiras eram montadas ao passo por uma hora. Os testes foram formados por etapas sucessivas de 10 minutos de marcha, sendo interrompido quando a frequência cardíaca atingia 150 batimentos por minuto e a concentração de lactato era maior que 4mmol/L ou a prova atingisse 70 minutos de duração. Avaliou-se o tempo de marcha, frequência cardíaca e concentração sanguínea de lactato. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Fisher a 5% de probabilidade. De zero a nove semanas de treinamento, o tempo de marcha aumentou progressivamente (p < 0,05), mas não houve diferença (p > 0,05) entre nove e doze semanas de treinamento. O protocolo de treinamento adotado foi adequado para condicionar equinos Mangalarga Marchador para competir em uma prova de marcha realizada de acordo com a regulamentação da Associação Brasileira de Criadores do Cavalo Mangalarga Marchador.