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Brasileiro de Hipismo (BH) represents an open population that permits genetic input from breeds recognised by the World Breeding Federation for Sport Horses. The aim of this study was the genetic characterisation of the population as the first of a series aiming at the consolidating the current selection programme. The Brazilian Association of the Brazilian Sport Horse Breeders provided genealogical data from 1977 to 2011. A data bank containing 34,393 horses was analysed for population genetic parameters including: individual inbreeding (F), effective population size (Ne), effective number of founders (fe), effective number of ancestors (fa), and number of founder genome equivalents (fg). Analysis were run twice: for animals born until 1995 (PREVIOUS) and for those born in the last 15 years (15YEARS). Ne estimated via paired increase in coancestry consisted of 188.59 (±3.24) animals. fe was 466 and 222 for PREVIOUS and 15YEARS, respectively. Ancestors were represented by fa of 274 and 129. Mean F for 15YEARS was 0.6%; 1444 animals were inbred, with mean inbreeding of 3.33%. The difference found in fa and fe parameters, between PREVIOUS and 15YEARS, indicated the loss of original alleles. The increase in contribution from some founders represents the breeder's preference for a few horses, without the negative effect of high inbreeding levels. Brasileiro de Hipismo genetic variability agrees with its large based formation history, and should allow for genetic gain of heritable traits through selection.

O presente estudo foi delineado com o objetivo de verificar a necessidade de inativar o leite em pó desnatado reconstituído, bem como o uso do leite desnatado UHT como diluente de sêmen eqüino resfriado. Para tanto, foram efetuados dois experimentos. No primeiro experimento, 4 diluentes foram testados: leite desnatado não inativado, leite desnatado inativado, leite desnatado UHT, marca A e leite desnatado UHT marca B. 20 coletas de sêmen foram realizadas. O sêmen resfriado a +4°C foi avaliado quanto à motilidade progressiva e motilidade total nas 0 , 24 e 48 horas posteriores à diluição. No segundo experimento, um total de 101 ciclos foram utilizados, inseminando-se as éguas com sêmen diluído em leite desnatado não inativado e leite desnatado inativado. A diluição foi realizada numa proporção de 1:2 (sêmen: diluente) e a dose inseminante mínima utilizada foi de 500x10(6) espermatozóides. Conclui-se que não há necessidade de inativar o leite em pó desnatado, reconstituído, na sua utilização como diluente de sêmen eqüino resfriado, e que o leite desnatado UHT pode ser utilizado como diluente para preservar sêmen eqüino resfriado.

The objective of this retrospective study was to evaluate the effect of management strategies aiming to improve animal well-being on pregnancy and embryonic death (ED) rates. Breeding records of a cohort of 1206 Thoroughbred mares brought to a stallion station facility, to be bred with the stallions housed there, were evaluated during ten breeding seasons. Mares were blocked according to management strategies in two groups: Stress and Relax. Strategies used to improve animal well-being (Relax group) were as follows: stopping the teasing routine, reducing or eliminating stall confinement, reducing the number of mares per group and maintaining herd stability during the breeding season. In barren mares, the pregnancy rate was higher in the Relax group (91.8%) when compared to the observed in Stress group (84.7%). However, no difference in pregnancy rates were observed (Stress = 85.2% vs. Relax = 86.2) in foaling mares. ED rate was higher in barren and foaling mares of the Stress group mares (25.5% and 26.8%, respectively) compared with the Relax group (16.1% and 14.7%, respectively). No significant differences were observed on foal heat pregnancy rate between groups; yet, the embryo loss on foal heat was significant reduced in Relax mares (Relax = 8.7% vs Stress = 24.5%). In conclusion, management strategies aimed to reduce social stress can reduce early pregnancy losses and the average cycles per pregnancy, improving reproductive performance in mares.

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