Seroprevalence of retrovirus in North American captive macropodidae

Laboratory records of serology results from captive macropodidae sampled between 1997 and 2005 were reviewed to assess the seroprevalence of retrovirus exposure. Serum samples from 269 individuals (136 males, 133 females) representing 10 species of macropods housed in 31 North American captive collections were analyzed for retrovirus antibody using an indirect immunofluorescent assay. The prevalence of positive antibody titers comparing male versus female, between species, between age groups, and among animals with identified parentage was examined by nonparametric statistical analyses. Median age of animals at time of sample collection was 36 mo (range 2-201 mo). Total percentage seropositive was 20.4%. Serum antibody was detected in 31 of 47 (66.0%) tammar wallaby (Macropus eugenii), nine of 24 (37.5%) yellow-footed rock wallaby (Petrogale xanthopus), four of 11 (36.4%) swamp wallaby (Wallabia bicolor), 10 of 80 (12.5%) red-necked wallaby (Macropus rufogriseus), and one of 54 (1.9%) parma wallaby (Macropus parma). No individuals of western gray kangaroo (n=3) (Macropus fuliginosus), eastern gray kangaroo (n=19) (Macropus giganteus), common wallaroo (n=6) (Macropus robustus), red kangaroo (n=11) (Macropus rufus), or Matschie's tree kangaroo (n=14) (Dendrolagus matschiei) were positive for retrovirus antibody. These results demonstrate that five species of captive macropods have a history of exposure to retrovirus, with the highest percentage seropositive and highest statistical correlation in M. eugenii (pair-wise Fisher's exact test, alpha = 0.05). Additionally, one wild-caught M. eugenii was confirmed seropositive during quarantine period, indicating that retrovirus exposure may exist in wild populations.     

Characterisation of and immunity to the aerobic bacteria found in the pouch of the brushtail possum Trichosurus vulpecula

The bacterial composition of the brustail possum (Trichosurus vulpecula) pouch was characterized throughout the reproductive cycle using brushtails from an Australian captive breeding colony (45 swabs) and a wild population in New Zealand (26 swabs). Gram-positive coccal species predominate throughout the reproductive cycle. Enteric Gram-negative rods, particularly Escherichia coli, were most prevalent when a pouch young was present and was most likely the result of faecal contamination from the pouch young. As culturing is only able to detect a proportion of bacteria present in a particular environment, molecular 16S rDNA sequencing was carried out on DNA extracted from a pouch wash of a female carrying a pouch young to gain a more accurate assessment of the pouch microflora. This approach identified approximately five times the number of bacterial species when compared to culture results. The majority detected were Gram negative rods or most closely related to Gram-negative rods species. Brushtails are immunologically immature at birth yet survive in a pouch colonised with potentially pathogenic bacteria. A haemagglutination assay was used to determine whether antibodies to a frequently isolated bacterium (Klebsiella pneumoniae) were transferred via milk from mother to pouch young. IgG antibodies were detected in maternal serum, milk and pouch young serum. In young over 70 days, antibody titres were significantly higher than those found in maternal serum, suggesting that the young is capable of producing adult type antibodies to pouch bacteria at this time.     

Reaction of the Captive Infant Baboon to a Surrogate Mother

Baboon infants were captured with their mothers in the Loskopdam area. The infants were separated from their mothers and raised in a laboratory. Each infant was placed with a surrogate mother. The infants accepted their surrogate mothers immediately. The very young infants spent most of their time with the mother where they suckled and slept for long periods. The older infants spent less time with their mothers. They only returned to the mother to be fed, to sleep or when frightened. The surrogate mothers that we have designed satisfied the needs of the infant. Thus infants were raised successfully in the laboratory.     

The effect of oestrus and the presence of pouch young on aerobic bacteria isolated from the pouch of the tammar wallaby, Macropus eugenii

Qualitative changes in the culturable, aerobic bacterial flora isolated from the tammar pouch have been documented over the period leading up to oestrus, at the time of anticipated birth and in absence and presence of pouch young of varying ages. In a group of 12 animals studied thirty species of aerobic bacteria were isolated. Twenty five species were found in pouches with no pouch young, 9 in pouches with young less than 3 weeks of age and 9 in pouches containing older animals. Gram positive organisms including Corynebacterium spp., Micrococcus spp. and Staphylococcus spp. were the most frequent isolates, regardless of reproductive status. Whilst Gram-negative rods Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterobacter aerogenes, and Escherichia coli were found in pouches with and without pouch young, but not in pouches close to oestrus, at the time of birth or in the presence of very young animals (<6 days). While pouches without pouch young displayed the greatest diversity of bacterial species, there were still significant numbers of bacterial species in those containing pouch young. Results suggest that the microbial population of the tammar pouch does not seriously compromise the well-being of the young animal during crucial stages of immunological development. The data are consistent with observations on the microflora of the quokka pouch but not with data from the koala.

Résumé

Les changements dans la diversité et la composition des populations de bactéries aérobies, isolées de la poche du tammar wallaby et cultivées, ont été suivis au cours de la période précédant l'oestrus, au moment de la naissance du jeune et après la naissance, dans des poches avec ou sans jeune. Trente différentes espèces de bactéries ont été isolées de la poche de 12 animaux: 25 espèces isolées de poches vides, neuf espèces de poches contenant un jeune de moins de trois semaines et neuf espèces de poches contenant un jeune de plus de trois semaines. Les bactéries Gram-positives Corynebacterium spp., Micrococcus spp. et Staphylococcus spp. ont été les plus fréquemment rencontrées, et ce quelque soit la période du cycle reproductif. Les espèces Gram-negatives Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterobacter aerogenes, et Escherichia coli ont été constamment isolées de poches vides, lorsque le tammar n'était ni en période proche de l'oestrus, ni proche de la naissance et ont été constamment isolées de poches contenant un jeune si celui-ci était agé de plus de six jours. Les plus grandes diversités spécifiques ont été relevées dans les poches vides, bien que les poches contenant un jeune ont toujours présenté un nombre significant d'espèces bactériennes. Les résultats suggèrent que les différentes populations bactériennes présentes dans la poche du tammar ne semblent affecter ni le bon dévelopement, ni la santé du jeune dans la poche, spécialement lors du dévelopement de ses capacités immunologiques. Ces résultats sont en accord avec ceux ceux obtenus pour le quokka, mais differents de ceux obtenus pour le koala.     

Analysis of the expression of immunoglobulins throughout lactation suggests two periods of immune transfer in the tammar wallaby (Macropus eugenii)

Marsupial young are born in an under-developed state without mature immune responses. Prior to the maturation of an immune system, marsupial young are heavily reliant upon immune factors secreted in the milk to defend them against potential microbial pathogens in the environment. In this study, we identified and characterized the immunoglobulin heavy chain constant regions, light chains, polymeric Ig receptor (pIgR), J chain, neonatal Fc receptor (alpha chain) (FcRn) and the chemokine CCL28 from the model marsupial species, the tammar wallaby (Macropus eugenii). Low levels of conservation were seen in motifs in C and Cγ associated with receptor binding and or transcytosis, and this may have potential implications for functionality. We evaluated the expression of immunoglobulin genes in the tammar mammary gland throughout lactation and found that two periods of increased expression of immunoglobulin genes occur. These two periods coincide with the birth of the young, and with its first emergence from the pouch. This increased expression may represent a strategy for maternal immunological protection of the pouch young.     

Gastrointestinal Diseases of Marsupials

This article focuses on gastrointestinal diseases that affect 3 of the most common marsupials treated by veterinarians: the red kangaroo (Macropus rufus), Bennett’s wallaby (Macropus rufogriseus), and the sugar glider (Petaurus breviceps). Other marsupial species maintained in captivity include the eastern gray kangaroo (Macropus gigantus), the tammar wallaby (Macropus eugenii), and the wallaroo (Macropus robustus). Most all of the disease conditions discussed in this article are also diagnosed in the lesser species listed earlier. Marsupials derive their name from the presence of the marsupial bones (ossa marsupialia), which serve as the surface for the attachment of several abdominal muscles. The ossa marsupialia were once thought to support the marsupium (pouch), although this was an incorrect assumption. The metabolic rate of marsupials is generally considered to be approximately two-thirds that of eutherian or placental mammals. Marsupials belong to a unique group of animals whose development is characterized by a very short gestation, the birth of relatively underdeveloped young (joeys), and a lengthy period of lactational development that typically occurs in a pouch. The physiologic differences that exist between marsupials and eutherian mammals should be considered when managing disease conditions in these animals.     

Optimizing female allocation to reproductive technologies considering merit,inbreeding and cost in nucleus breeding programmes with genomic selection

Female reproductive technologies such as multiple ovulation and embryo transfer (MOET) and juvenile in vitro fertilization and embryo transfer (JIVET) have been shown to accelerate genetic gain by increasing selection intensity and decreasing generation interval. Genomic selection (GS) increases the accuracy of selection of young candidates which can further accelerate genetic gain. Optimal contribution selection (OCS) is an effective method of keeping the rate of inbreeding at a sustainable level while increasing genetic merit. OCS could also be used to selectively and optimally allocate reproductive technologies in mate selection while accounting for their cost. This study uses stochastic simulation to simulate breeding programmes that use a combination of artificial insemination (AI) or natural mating (N), MOET and JIVET with GS. OCS was used to restrict inbreeding to 1.0% increase per generation and also to optimize use of reproductive technologies, considering their effect on genetic gain as well as their cost. Two Australian sheep breeding objectives were used as an example to illustrate the methodology—a terminal sire breeding objective (A) and a dual‐purpose self‐replacing breeding objective (B). The objective function used for optimization considered genetic merit, constrained inbreeding and cost of technologies where costs were offset by a premium paid to the seedstock breeder investing in female reproductive technologies. The premium was based on the cumulative discounted expression of genetic merit in the progeny of a commercial tier in the breeding programme multiplied by the proportion of that benefit received by the breeder. With breeding objective B, the highest premium of 64% paid to the breeder resulted in the highest allocation of reproductive technologies (4%–10% for MOET and 19%–54% for JIVET) and hence the highest annual genetic gain. Conversely, breeding objective A, which had a lower dollar value of the breeding objective and a maximum of 5% mating types for JIVET and zero for MOET were optimal, even when highest premiums were paid. This study highlights that the level of investment in breeding technologies to accelerate genetic gain depends on the investment of genetic improvement returned to the breeder per index point gain achieved. It also demonstrates that breeding programmes can be optimized including allocation of reproductive technologies at the individual animal level. Accounting for revenue to the breeder and cost of the technologies can facilitate more practical decision support for beef and sheep breeders.     

利用JIVET技术快速繁育萨福克羊的研究

JIVET技术是一项利用生殖激素刺激幼畜卵巢,从而使其快速、高效生产卵母细胞的技术。对4只1月龄萨福克幼羔注射FSH和PMSG激素,48 h后采用手术法抽取幼羔卵母细胞,并在体外成熟;将成熟的卵母细胞与精子进行体外受精,将正常分裂的2~8细胞胚胎移植到6只同期发情的受体小尾寒羊子宫内。结果显示,采用激素法处理萨福克幼羔后共采集到可用卵母细胞109枚,体外成熟培养后得到成熟卵母细胞79枚,成熟率为72.48%;体外受精后得到正常卵裂胚胎34枚,卵裂率为43.04%;胚胎移植后有3只受体母羊怀孕,受胎率为50%,并分娩得到3只萨福克幼羔。综上提示,利用JIVET技术可以缩短萨福克羊的繁育周期,从而加快其繁育速度。     

Propagation of elite rescue dogs by somatic cell nuclear transfer

The objective of the present study was to compare the efficiency of two oocyte activation culture media to produce cloned dogs from an elite rescue dog and to analyze their behavioral tendencies. In somatic cell nuclear transfer procedure, fused couplets were activated by calcium ionophore treatment for 4 min, cultured in two media: modified synthetic oviduct fluid (mSOF) with 1.9 mmol/L 6‐dimethylaminopyridine (DMAP) (SOF‐DMAP) or porcine zygote medium (PZM‐5) with 1.9 mmol/L DMAP (PZM‐DMAP) for 4 h, and then were transferred into recipients. After embryo transfer, pregnancy was detected in one out of three surrogate mothers that received cloned embryos from the PZM‐DMAP group (33.3%), and one pregnancy (25%) was detected in four surrogate mothers receiving cloned embryos from the SOF‐DMAP group. Each pregnant dog gave birth to one healthy cloned puppy by cesarean section. We conducted the puppy aptitude test with two cloned puppies; the two cloned puppies were classified as the same type, accepting humans and leaders easily. The present study indicated that the type of medium used in 6‐DMAP culture did not increase in cloning efficiency and dogs cloned using donor cells derived from one elite dog have similar behavioral tendencies.     

Health and production measures for smallholder pig production in Kikuyu Division, central Kenya

A longitudinal study was carried out in Kikuyu Division (a peri-urban area in central Kenyan highlands) between January 1999 and December 1999 to estimate the baseline parameters on reproductive performance of the sow, as well as health and productivity of grower and preweaning pigs of smallholder herds. Data were collected on 155 breeding pigs, 795 grower pigs and 801 preweaning piglets in 74, 50 and 40 smallholder herds, respectively, using record cards that were updated during monthly visits.

The sow-level medians were: weaning-to-service interval 3 months; interfarrowing interval 6.4 months; number of live-born piglets 9.0; and number of piglets weaned per litter 7.5. The piglet crude morbidity incidence risk was 29%. The cause-specific incidence risks for the important health problems encountered in preweaned piglets were diarrhea (4.3%), pruritus (17.1%), and skin necrosis (4.2%). The estimated crude mortality incidence risk to 8 weeks of age was 18.7%. The cause-specific mortality incidence risks to 8 weeks of age for the important causes of mortality were overlying (9.9%), savaging (2.4%), unviable piglets (2.0%) and unknown (1.9%). Overall, 78.8% of the total live-born piglet mortality occurred during the first week postpartum with 69% of these deaths being caused by overlying. The grower-pig crude morbidity incidence risk was 20% and the cause-specific incidence risks of the important health problems encountered were gut edema (1.3%), pruritus (21.1%), and unknown (2.3%). The crude mortality incidence risk was 3.8% and the important causes were gut edema and unknown causes (cause-specific mortality incidence risks of 1.3 and 1.6%, respectively). The median weight:age ratio and average daily weight gain for the grower pigs were 5.1 kg/month of age and 0.13 kg/day, respectively. For preweaning pigs, the median average daily weight gain was 0.13 g/day.     

体细胞克隆太湖猪出生

以中国太湖猪胎儿成纤维细胞为核供体,以体外成熟卵母细胞为核受体,以杜洛克猪为代孕母猪,进行了太湖猪体细胞克隆技术的研究,成功地获得了首例体细胞克隆太湖猪仔猪.经微卫星DNA多态性鉴定,确定克隆猪来自供核细胞,与代孕母猪无亲缘关系.本研究将为体细胞克隆技术在我国太湖猪育种、建立人类疾病模型等研究方面提供可行的技术方法.     

A field study on the usefulness of milk progesterone determination to confirm estrus and pregnancy of dairy cows in the Fraser Valley area of British Columbia

A field study was conducted to determine the usefulness of milk progesterone determination at the time of breeding to confirm estrus and at 21 days postbreeding to detect open cows. Twenty-seven dairy farmers collaborated in this study by providing milk samples on the day of breeding and 21 days later, together with pregnancy diagnosis data and information on herd reproductive management. Herd size ranged from 15 to 175 cows, the average being 65 milking cows. Six hundred and sixty-seven breeding-day samples and 472, 21-day samples were provided by the farmers. Analysis of milk samples for progesterone by a solid phase radioimmunoassay showed that only 32 (4.8%) of the services were performed when the cow was not in estrus (progesterone > 1 ng/mL). Of the 472, 21-day samples, 337 (71%) showed progesterone levels of > 1 ng/mL, while 135 (29%) showed progesterone levels of < 1 ng/mL. Subsequently, 243 (72%) of the cows with progesterone > 1 ng/mL and eight (6%) of the cows with progesterone < 1 ng/mL were diagnosed pregnant by transrectal palpation, giving a pregnancy rate of 53%. Progesterone concentration on the day of breeding was not associated with season or herd size. However, progesterone concentration at 21 days and pregnancy rate were associated with herd size. These results indicate that fertillzation failure and/or early embryonic mortality, rather than inaccurate detection of estrus, are the major reproductive problems encountered by the dairy farmers in British Columbia. Furthermore, progesterone values at 21 days were closely related to reproductive status and indicate the usefulness of milk progesterone assay for the early detection of open cows.     

Opposing offspring sex ratio variations with increasing age and weight in mouflon mothers (Ovis musimon).

There are two main theories explaining offspring sex biases in polygynous mammals. Trivers and Willard (1973) argue that mothers with greater reproductive resources should invest in the sex with the greater variance in reproductive success, usually sons. In contrast, because daughters in many polygynous mammals stay with their mother and compete with her for food, Local Resource Competition theory (e.g. Clark, 1978; Silk, 1983) predicts that the mothers with the greatest reproductive resources should invest in daughters. We investigated the strategy of sex allocation of a captive, outdoor population of 139 mouflon mothers, Ovis musimon, kept in a game state. A complex picture emerged in which, despite weight and body condition being correlated with age in female mouflons, mothers lambed more daughters with increasing age but also, within a given age, gave birth to more sons with increasing weight. Results may be useful in game management aimed at increasing the recruitment or quality of males in managed populations.     

Reproductive efficiency in grazing lactating dairy cows under a programmed reproductive management system

OBJECTIVE: To evaluate the effectiveness of a reproductive management program consisting of combinations of Ovsynch/TAI and prostaglandin (PG) F(2alpha) treatments in Holstein dairy cows under a pasture-based dairying system. DESIGN: Field trial. PROCEDURE: A total of 1177 cows in 8 commercial dairy farms were randomly allocated to control and treatment groups. Treatment group cows received one of two interventions depending upon the number of days postpartum (DPP) before the planned start of breeding. Cows more than 50 DPP by the planned start of breeding received the Ovsynch/TAI treatment, consisting of gonadotrophin releasing hormone (GnRH) - PGF(2alpha)- GnRH plus timed artificial insemination. Cows between 40 and 50 DPP received a PGF(2alpha) treatment followed by oestrus detection and, if the cow was not seen in oestrus, the cow received a second PGF(2alpha) 14 days later. Control cows were submitted to twice a day heat detection followed by artificial insemination. The experimental period was the start of the breeding season plus 21 days for cows over 50 DPP at the start of breeding, and was 40-61 DPP for cows that calved later and passed their voluntary waiting period after the start of the breeding season. RESULTS: Submission rate was higher for the treated group than for the control group (84.9% vs. 55.1%; P < 0.0001), as was the conception rate (51.0% vs. 46.1%; P < 0.03). Due to farm variations, pregnancy rate was similar in both groups (38.5% vs. 28.2%; P > 0.1). Within the treated group, conception rate and pregnancy rate of the cows inseminated after a PGF(2alpha) were higher than for timed artificial inseminated cows (51.4% vs. 32.6%; P < 0.001), and (37.8% vs. 32.6%; P < 0.001). CONCLUSION: A programmed reproductive management protocol may improve reproductive efficiency in dairy farms with seasonal breeding, by increasing submission and conception rates at the beginning of the breeding season and/or at the end of the voluntary waiting period. Fertility of cows bred after a PGF(2alpha) synchronised heat was greater than after an Ovsynch/TAI protocol.     

日本大耳兔生后时期若干性状的初步研究

本研究对日本大耳兔初生、２１、３５、６０、９０、１２０、１５０、１８０日龄和成年等不同生长阶段生长发育和繁殖力、肥育性能进行跟踪观察和测定。结果表明，初生至９０日龄生长速度呈直线上升，之后则急剧下降。初生、２１、３５、６０、９０、１２０、１５０、１８０日龄和成年体重分别为６３．５、２３６．８、５１８、１１４７、２０６３．２、２８６８．７、３５０５．６、３９８７．７和４１５９．２ｇ；窝均产仔８．１５只，仔兔２１日龄窝重１９２９．５ｇ，３５日龄断奶成活率９６．９％；肥育期（３５～９０日龄）日增重３３．３ｇ，屠宰率４７．１％，料肉比３．９９；３月龄鲜皮重２４５．０ｇ，皮板面积８８９．３ｃｍ２。由此可见，日本大耳兔繁殖力和母兔哺育力较强，早期生长发育快，符合正常生长发育规律，由于屠宰率和饲料转化率不高，不宜作商品兔生产，但作为杂交母本生产商品兔可取得较好效果     

Full-term delivery of river buffalo calves (2n = 50) from in vitro-derived vitrified embryos by swamp buffalo recipients (2n = 48)

Field trials were carried out on the use of swamp buffaloes (2n = 48) as recipients of in vitro-derived vitrified river buffalo (2n = 50) embryos. River buffalo embryos were produced through a total in vitro production system using frozen semen from a top progeny-tested bull and slaughter-house-derived ovaries and cryopreserved by a vitrification technique. Recipient swamp buffaloes were Philippine carabaos selected on body condition, parity, and reproductive status and owned by village farmers. Eighty post-warmed riverine embryos were transferred non-surgically to 40 swamp buffalo recipients, of which three healthy riverine calves were born by normal delivery and one stillbirth, representing a 5.0% (4/80) full-term development and 10% (4/40) calving rate with 75% (3/4) normal and 25% (1/4) stillbirth. The results demonstrate that, under field conditions and despite the difference in chromosome number between the embryo and recipient, swamp buffaloes are potential surrogate mothers of imported, genetically superior river buffalo frozen embryos. Thus, embryo IVP-vitrification and transfer technology is a potential tool in the propagation of genetically superior buffaloes. Precautionary measures, however, are recommended to avoid dystocia and stillbirth.     

Age-Dependent Effect of Foal Heat Breeding on Pregnancy and Embryo Mortality Rates in Thoroughbred Mares

The aim of the present study was to evaluate the correlation of age and heat cycle to determine reproductive efficiency in young and aged Thoroughbred mares bred on foal heat (FH) or on second heat (SH) after foaling. Embryo mortality (EmbM) was determined every time a mare was found open after a positive pregnancy diagnosis. Parturition to breeding interval, pregnancy rate (PregR) and EmbM rate were the dependent variables and the treatments were breeding on the FH or on SH. The cutoff age to obtain above-average probability for the EmbM was 10 years old. PregR in mares bred on FH was lower compared with SH (P < .01); however, it was neither affected by the age of mares (P > .05) nor by the age group of mares (P > .05). Regarding FH and SH, there was a difference in PregR in young mares (P < .01), unlike in aged mares (P > .05). EmbM rate was not different between mares bred on FH or SH (P > .05) although it was affected by age of mares (P < .01). EmbM was higher in oldest than young mares (P < .01). Aged mares bred on FH had a significantly higher EmbM rate compared with the young group also bred on FH (P < .01). In conclusion, the reproductive efficiency of Thoroughbred mares bred on FH is dependent of the age. Aged mares (≥10 years old) should be bred at their SH to reduce EmbM and improve reproductive performance.     

后备母猪的遗传繁育和营养促进对母猪繁殖效率

繁殖效率是现代成功猪业生产体系母系性能评定指数。全基因组选育法,结合传统的数量性状位点基因选择(QTL)的遗传改进进展使得遗传优势能有益于最好种用性能的生产效率。一个优秀的种用母种群是从一个好的后备母猪生长发育方案开始的,基于这个方案有3个重要基础。他们是遗传基础、生理基础和营养基础。该文将讨论它们在现代种用猪群的繁殖效率改进中的作用,重点是集中在后备母猪。     

维生素对种兔繁殖力作用影响的研究与分析

为了研究维生素对种兔繁殖力作用的影响。试验采用新设计的配方饲料同兔场原来采用的常规配方饲料在相同的条件下进行饲喂试验,分析维生素对种兔发情时间、受胎率、产仔胎数、产仔数、断奶仔兔成活率的影响。选用健康繁殖年龄基本相同的种兔100只,分A、B2组,每组50只,公母比例1∶4,A组饲喂常规饲料,B组饲喂试验饲料。试验结果表明,维生素对种兔的繁殖力作用是显著提高的(P<0.01),在试验的4个月时间里,B组母兔发情只数是A组母兔发情只数的2.46倍;B组母兔平均受胎率是A组母兔平均受胎率的1.72倍;B组母兔产仔数是A组母兔产仔数的11.58倍;B组仔兔成活率是A组仔兔成活率的2倍,达到了理想的配种繁殖效果。     

Reproductive Parameters of Mangalarga Marchador Mares in a Commercial Embryo Transfer Programme

The objective of this study is to evaluate the reproductive efficiency in donors and recipient Mangalarga Marchador mares in commercial programmes of embryo transfer (ET) and the effects of some reproductive characteristics and ET methodology on conception rates in the recipient mares. A total of 1140 flushing procedures were performed and 830 embryos (72.8%) were recovered. There were no differences between the rates of embryonic recovery in the different breeding seasons (p > 0.05) and 92.8% of the recovered embryos were 8–9 days old. There was no difference in the embryonic recovery regarding the collection order from the first to the ninth embryo collection along the breeding season, as well as among mares inseminated during the foal heat or subsequent cycles (p > 0.05). Pregnancy rates observed in the total period of all reproductive seasons at 15, 30, 45 and 60 days of pregnancy were 73.4, 69.9, 66.7 and 64.5%, respectively. Differences in pregnancy rate and early embryonic loss rates were not observed between embryos transferred immediately after collection (66.8% and 13.5%) and embryos transported at room temperature for periods of <1 h (62.9% and 14.4%; p > 0.05). Pregnancy rates were higher when the interval between ovulations of donor and recipient mares remained between ?3 and ?2 days (p < 0.05), and the lowest rates were observed for intervals of ?6 days (p < 0.05) with intermediary values for intervals of ?1, 0 and +1 (p > 0.05). Embryonic loss rates, however, did not differ between intervals of ovulation’s synchronism between donor and recipient mares (p > 0.05). This flexibilization in the ovulatory synchronism between donor and recipient mares optimizes the use of recipient mares, thus reducing costs and facilitating management of horse breeding farms.