Stud management involves the systematic and strategic breeding of horses to enhance desirable traits, maintain genetic diversity, and ensure the health and welfare of both mares and stallions. This practice encompasses a range of activities, including the selection of breeding pairs, monitoring of reproductive health, and management of breeding cycles. Key aspects of stud management include assessing genetic compatibility, managing nutrition and health care, and implementing breeding technologies such as artificial insemination or embryo transfer. Effective stud management requires a comprehensive understanding of equine genetics, reproductive physiology, and husbandry practices. This page gathers peer-reviewed research studies and scholarly articles that explore various facets of stud management, including genetic evaluation, reproductive technologies, and the impact of management practices on breeding outcomes.
Jeffcott LB, Rossdale PD.The current knowledge of the clinical signs, epidemiology and pathogenesis of abortion due to the equid herpesvirus (EHV 1) is reviewed. The relationship between the respiratory and abortigenic forms of the disease is discussed as well as the low incidence of virus abortion in the UK compared to some other parts of the world. Some practical aspects of the disease as they affect stud management are considered including methods of diagnosis, prophylaxis and the necessary action to be taken to prevent spread of infection.
Sullivan JJ, Pickett BW.Approximately 1 week was required to stabilize the extragonadal sperm reserves in stallions ejaculated daily for 10 weeks. The true daily sperm output of a stallion was equal to the mean daily sperm output of seven ejaculates +/- 1-35 X 10(9) spermatozoa. Mean concentrations of spermatozoa/ml and number of spermatozoa/ejaculate were higher (P less than 0-01) for X1 and X3/week ejaculation frequencies than for a X6/week frequency. Sperm output/week was nearly identical for a X6/week frequency. Sperm output/week was nearly identical for the X3 and X6 frequencies and higher (P less than 0-01) tha...
van der Holst W.Season was shown to markedly influence semen characteristics of stallions in Holland, including ejaculate volume, sperm motility, total number of spermatozoa/ejaculate and the percentage of spermatozoa showing morphological abnormalities. Maintenance of normal stallions in continuous light during the winter months and administration of a vitamin and mineral supplement to sub-fertile stallions before the start of the breeding season appeared to improve spermatogenesis significantly.
Irwin CF.A total of 487 Standardbred and Thoroughbred mares at two studs were manually tested for pregnancy at 20 to 24, 30 to 34, and greater than 42 days after service and the abortion rate compared to that obtained in previous years when only the greater than 42-day test was performed. The results indicated that early manual pregnancy testing does not increase the abortion rate if undertaken carefully and enables non-pregnant mares to be re-mated earlier in the same season.
von Lepel J.A central control system for German Thoroughbred horses is described. Autumn examination of mares and stallions enables them to be classified according to breeding potential. The results of 25 years of study are reported.
Pascoe RR, Bagust TJ.Equine coital exanthema can be produced experimentally in stallions by inoculation with an equine herpesvirus (strain 65/61) and be transmitted during coitus with an infected mare. Serological responses to this infection include the production of complement-fixing and serum-neutralizing antibodies which reach maximum levels 14 to 21 days after infection. Complement-fixing antibodies decline rapidly and are usually not detectable by 60 days after infection, whereas serum-neutralizing antibody activity is maintained for at least 1 year. This disparity provides a useful method for the diagnosis o...
Osborne VE.Foaling figures for Thoroughbred mares in Australia show a puzzling disparity between conception and foaling rates in the second half of the 22 years of official data collection between 1950 and 1972. In the first 9 years of the survey, the live foal percentages rose in parallel with conception rates, but then a divergence of the figures occurred with the conception rate continuing to improve by 6-25% while the foaling rate improved by only 0-01% over the same period. An hypothesis supported by data from two studs is considered that stress factors additional to those experienced by mares in th...
Sullivan JJ, Turner PC, Self LC, Gutteridge HB, Bartlett DE.Reproductive efficiency was evaluated for 838 Quarter-horse mare-years on five farms and 939 Thoroughbred mare-years on seven farms over 4 years. The pregnancy rate from first service was 51% for Quarter-horse mares and 43% for Thoroughbred mares (P less than 0-05). The cumulative pregnancy rate after five services was 85% for Quarter-horse and 77% for Thoroughbred mares (P less than 0-05). First-service-period pregnancy rates were 44, 40 and 54% for maiden, barren and foaling mares, respectively. Cumulative pregnancy rates after five service-periods were 84, 74 and 84% for maiden, barren and ...
Frhr J, Lepel V.A high fertility rate depends on many different factors and is always related to inheritance and enviorment. The successful feritly control system in the German Thoroughbred breeding industry shows that fertility can be increased by good management and veterinary supervision. The insemination of horses with frozen semen is discussed. Replacement of natural service by A.I. with frozen semen is not generally accepted in horsebreeding, as the conditions are entirely different from cattle breeding. However, there are several ways in which A.I. can be assistance in stud management.
Hiepe T, Nickel S, Siebeke F.The eggs of Strongyloides westeri were found in the faeces of the foals from the 16th day of their life, with a peak in their numbers between the 30th and 40th day of life. Egg release ceased in all foals irrespective of their date of birth in the months July-August. Parallel examinations of the mares were negative. Recommendations for the control of strongyloidosis in foals are given.
Lowis TC, Hyland JH.The occurrence of fertile oestrus early in the breeding season is of paramount importance to the Thoroughbred industry to facilitate early conception. This paper compares 2 techniques for inducing fertile oestrus in anoestrous mares using either an extended photoperiod alone or together with gonadotrophin-releasing hormone (GnRH) infusions. Eleven mares were placed under conditions of 16 h light and 8 h darkness and 5 of these were implanted with osmotic minipumps delivering approximately 100 ng GnRH/kg/h for 28 days (treated mares). The treated mares ovulated 27.7 days earlier than and concei...
Scholtz M, Guthrie AJ, Fosgate GT, Schulman ML.Population demographics and reproductive performance of Thoroughbred populations have been described, but the most recent assessment of the South African Thoroughbred population was reported two decades ago. Objectives of this study were to report demographic data for selected Thoroughbred breeding populations and to analyse selected mare-level variables in association with foaling outcomes, as predictors of reproductive performance. The National Horseracing Authority of Southern Africa's stud health scheme requires annual screening of Thoroughbred stallions, maiden and barren mares for venere...
Mack JK, Remler HP, Senckenberg E, Kienzle E.This study investigated the energy requirements of Warmblood foals with a change of the stud at weaning. Methods: Nine colts purchased at weaning participated in the study aged approximately 6 months to 1 year. They were transported to the stud by their breeders either having been separated from their dams in their home stable or upon arrival at the stud. The foals were offered a late first cut of haylage, oats and foal starter feed. To ensure individual feeding of concentrates, the foals were tethered twice daily. The total combined haylage intake of all foals per day was recorded. Individu...
Yurdaydin N, Tekin N, Gülyüz F, Aksu A, Klug E.An Arab broodmare herd of 30 mares age ranging from 4 to 12 years was grouped into 3 groups (group A, B, C) with 10 mares each and exposed to three different methods of cycle synchronisation. Group A mares received two PGF2 alpha injections 14 days apart. Group B mares got additionally 2,500 IU of hCG 5 days after second prostaglandin application. Group C consisted of mares which had foaled in a synchrony of one week and got a PGF2 alpha injection 3 weeks after parturition. All the mares responding to synchronisation were inseminated closely to ovulation detected by serial rectal palpations wi...
Dowsett KF, Pattie WA.Semen was collected from 222 stallions of 13 breed or colour types in southern Queensland and northern New South Wales. A total of 648 collection attempts were made, using an artificial vagina, during 4 consecutive breeding seasons (1974/5 to 1977/8). Modifications were made to the techniques used by previous workers because collections were made at commercial studs using minimal animal restraint. Of all collection attempts, 621 (96%) were successful, while at least one semen sample was collected from each of 216 stallions (97%). There were no significant relationships between stallion collect...
Merkt H.A stallion got fatal injuries by kicks of a maiden mare because a so called "panic hook" untied spontaneously. The use of such hooks to secure mares during mating should therefore not be recommended.
de Vries PJ, Zandee AR.As part of the veterinary surveillance of horse breeding management, the veterinarian is increasingly often requested to predict ovulation and to give a breeding or insemination advice accordingly. The result of a teasing procedure is indispensable for this advice. A suggestion is made for the quantification of oestrus signs. Oestrus symptoms are classified into four categories. In addition, various factors are mentioned, which affect the result of a teasing procedure.
Roach J, Arango Sabogal JC, Smith K, Foote A, Verheyen K, de Mestre AM.Risk factors associated with equine reproductive efficiency have been identified along with those associated specifically with early pregnancy loss (EPL). In contrast, no studies have reported risk factors associated with abortion (loss between day 70 and 300 post-cover). Given the causes of abortion differ to those of EPL, likely too will the risk factors. A retrospective cohort study was carried out to identify risk factors associated with abortion in UK and Irish based Thoroughbreds, collecting data on 20 exposure variables over a five-year period. A generalized linear mixed model was utili...
Lind EO, Christensson D.In the last few years stud farms have experienced increasing problems with Parascaris equorum infections in foals despite intensive deworming programs. This has led to the question as to whether the anthelmintic drugs used against this parasite are failing. This study aimed to investigate the efficacy of ivermectin, fenbendazole and pyrantel on the faecal output of ascarid eggs of foals. Methods: A Faecal Egg Count Reduction Test (FECRT) was performed on nine large studs in Sweden. Anthelmintic drugs were given orally and faecal samples were examined for ascarid eggs on the day of deworming an...
Bolwell CF, Rogers CW, French NP, Firth EC.There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual yearlings during a sales preparation is scant. Objective: To describe the exercise and health problems of Thoroughbred yearlings during preparation for sales, and to identify variations in exercise between and within farms. Methods: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise...
Pessoa V, Ramilo DW, Pereira da Fonseca I, Ferreira MB, Marti E, Tilley P.Insect Bite Hypersensitivity (IBH) is a common cutaneous disease, affecting a large number of horses worldwide. Several studies have identified Culicoides spp. saliva as a clinically relevant allergen source. The prevalence of IBH in Portugal, particularly in Lusitano horses, is still not known. However, the environmental characteristics of the national territory are favorable to the activity of Culicoides, and several species of this genus can be found, namely C. imicola and C. obsoletus/C. scoticus. In this study we characterized the Culicoides population present in Lusitano stud farms with ...
Perdomo-González DI, García de Paredes RLA, Valera M, Bartolomé E, Gómez MD.The studbook of Pura Raza Menorquina horses only permits the use of black-coated animals with a small quantity of white marks as breeding stock. Its breeding program uses linear morpho-functional traits as selection criteria. Our aim was to estimate the genetic parameters of linear morpho-functional traits, and reveal relationship of quality of black coat color (QB) and percentage of white marks (WM) with the other morphological and functional linear traits in this breed. A total of 46 linear traits were scored by four appraisers using seven classes, with a total of 772 records from 333 animal...
Dolan M, Cargill C, Martin F, Davenport P, Franks D, Lightfoot J.A bacteriological and serological survey for evidence of contagious equine metritis (CEM) was made during the 1980 breeding season on 3 horse studs in South Australia with a history of previous infection. Swabs from the clitoral sinus and the cervix were cultured for Haemophilus equigenitalis and serum was screened for antibody using the complement fixation test (CFT) and the enzyme-linked immunosorbent assay (ELISA). The specificity of both tests was greater than 0.99 but the ELISA was more sensitive in detecting antibody in infected mares. On the evidence presented it was concluded that H. e...
Tanner JC, Barrell GK.Despite being a large commercial breeding industry, there is little published data on the reproductive success of Standardbred mares. Objective: To quantify the reproductive performance of Standardbred mares under artificial breeding systems in a commercial setting and determine the incidence of early embryonic and other pre-partum losses. Methods: Retrospective cohort study. Methods: Data from four commercial farms were collected across four breeding years, and all mares were bred via artificial insemination. A total of 3995 mares contributed 7229 mare years. First-cycle pregnancy rate (FCPR)...
Ainsworth CG, Hyland JH.Continuous infusion of gonadotrophin releasing hormone (GnRH) has been shown to induce oestrus and ovulation in experimental mares in seasonal anoestrus. The present study sought to apply this form of treatment to anoestrous mares subjected to normal management procedures on 15 commercial Thoroughbred studfarms in Australia. The GnRH was delivered via subcutaneously implanted osmotic minipumps (OMP) at dose rates of 100 ng/kg/h and 200 ng/kg/h. The ovaries of treated mares were palpated on the day of OMP insertion (Day 0) and blood samples were collected twice weekly from a proportion of mares...
Crespo F, Wilson R, Díaz-Jimenez M, Consuegra C, Dorado J, Barrado BG, Gosálvez J, Smit RL, Hidalgo M, Johnston S.Horses are long-day seasonal breeding animals, however, with modern stallion reproductive management it is important for collection of semen during periods that are not part of the traditional breeding season. This study was conducted to examine variation in the seminal characteristics of individual stallions in Avila, Spain during 1 year with a particular emphasis on sperm DNA fragmentation. Semen was collected twice per season from a total of 20 stallions. There was a marked seasonal effect on all seminal characteristics, with the greatest on progressive motility, % membrane integrity and le...
Grewar JD, Thompson PN, Lourens CW, Guthrie AJ.Thoroughbred foal body temperature data were collected from shortly after birth until shortly after weaning during the 2007/2008 season on a stud farm in the Western Cape Province of South Africa. Equine encephalosis (EE) caused by EE virus (EEV) serotype 4 (EEV-4) occurred in the foal group during the first autumn after their birth (March and April 2008). A descriptive study was undertaken to provide data on the EEV maternal antibody status, the association between pyrexia and EEV infection, and the incidence of infection amongst the foals prior to and during the episode. This included the fr...
Dusek J, Munk Z.The breeding documentation of the English Thoroughbred horse breeding farm at Napajedla was analyzed to study some effects acting upon the fertility of studs and mares and the length of gravidity. The heritability of fertility is the subject of this report. The normality of the distribution of fertility was tested by processing 300 data on fertility at the given significance level sup / Fn(xi) - F(xi) / less than or equal to Dn(a). The value of the supreme D(300) = 0.108 is lower than the critical level for alpha 0.05. The estimation of fertility heritability coefficient indicates that h2 = 0....
Sullivan JJ, Turner PC, Self LC, Gutteridge HB, Bartlett DE.Reproductive efficiency was evaluated for 838 Quarter-horse mare-years on five farms and 939 Thoroughbred mare-years on seven farms over 4 years. The pregnancy rate from first service was 51% for Quarter-horse mares and 43% for Thoroughbred mares (P less than 0-05). The cumulative pregnancy rate after five services was 85% for Quarter-horse and 77% for Thoroughbred mares (P less than 0-05). First-service-period pregnancy rates were 44, 40 and 54% for maiden, barren and foaling mares, respectively. Cumulative pregnancy rates after five service-periods were 84, 74 and 84% for maiden, barren and ...
Mumford JA, Rossdale PD, Jessett DM, Gann SJ, Ousey J, Cook RF.An extensive outbreak of EHV-1 abortions occurred on a stud farm in England in 1985. Of the 67 pregnant mares present on the stud farm, 31 were challenged with EHV-1, resulting in the loss of 22 fetuses or foals. Laboratory investigations revealed that the spread of the virus closely followed movement of apparently healthy mares (during the incubation period of the infection). During the outbreak mares were challenged 1-4 months before the expected foaling date. There was no relationship between the gestational age at the time of challenge and the subsequent outcome of infection in terms of ab...
Todd ET, Hamilton NA, Velie BD, Thomson PC.Horses produce only one foal from an eleven-month gestation period, making the maintenance of high reproductive rates essential. Genetic bottlenecks and inbreeding can increase the frequency of deleterious variants, resulting in reduced reproductive levels in a population. In this study we examined the influence of inbreeding levels on foaling rate, gestation length and secondary sex ratio in Australian Thoroughbred mares. We also investigated the genetic change in these traits throughout the history of the breed. Phenotypic data were obtained from 27,262 breeding records of Thoroughbred mares...
Ali A, Alamaary M, Al-Sobayil F.The aim of this study was to evaluate the reproductive performance of the Arab mares in the Kingdom of Saudi Arabia (KSA). Methods: Managers of 26 studfarms containing 1014 Arab mares at five districts were asked to complete a questionnaire on the reproductive efficiency of their mares. Results: The mean age at first mating was 3.06 ± 0.5 years. Mares were mated equally in winter and all over the year. Natural mating was mostly used (76.9%). The means of estrus duration and estrus interval were 6.58 ± 1 days and 19.57 ± 1.8 days, respectively. The means of first service and over- all pregna...
Sharma S, Davies Morel MC, Dhaliwal GS.Decreased reproductive performance due to summer stress is a well known phenomenon in farm livestock. Whether this occurs in the mare and specifically how this might affect postpartum reproductive activity and performance, especially at Foal Heat (FH), is unknown. This study, therefore, aims to investigate this and the factors that might affect postpartum reproductive activity. Reproductive records of 228 Thoroughbred mares (694 mare years) bred in subtropical north-western India were retrospectively analysed. Overt oestrous activity occurred within 21 d postpartum in 92.94% (645/694) of mares...
Noue P, Bernabé J, Rampin O, Vidament M, Dumas T, Palmer E, Magistrini M.The sexual behavior of 42 stallions from French national and private studs was examined in two contexts: semen collection for artificial insemination (AI) and in-hand natural service (NS). Each stallion was observed twice in the same context. Erection and ejaculation latencies, the number of mounts leading to ejaculation, dismount latency and total breeding time were measured and compared between AI and NS. Mount without erection was rare (6/83 observations). Erection latency was 89+/-11s, and was not different between NS (62+/-22s) and AI (100+/-13s, P=0.128). Stallions ejaculated after eithe...
Thompson K, Taylor J, Mendez D, Chicken C, Carrick J, Durrheim DN.There are almost 9,500 full-time employees in Australia's thoroughbred horse breeding industry. During foaling, they can be exposed to bodily fluids and mucous membranes which may present risks for zoonotic disease. These risks can be mitigated through personal biosecurity strategies. The aim of this study was to identify which personal biosecurity strategies were more or less likely to be adopted by workers. Seventeen participants representing 14 thoroughbred breeding farms and three equine veterinary practices in Australia's largest thoroughbred breeding region trialed up to 16 stakeholder-n...
