Effects of Age and Sex of The Foal on The Gestation Length of Thoroughbred Mares (original) (raw)
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Reproductive parameters of Thoroughbred mares in Croatia
2014
For the purpose of gaining better cognition on Thoroughbred breeding in Croatia, reproductive parameters of 87 Thoroughbred mares were analyzed. An average age of the first covering and foaling were 5.9 and 6.6. years, respectively. The average gestation length was 341.1 days and the most frequent foaling period (20.2% of foalings) was recorded between 336 to 340 days of gestation. Prolonged gestation period (p<0.05) was determined in colts. The gestation length was the longest in January (344.4 days) and the shortest in July (324.0 days). Between the gestation length and the age of the mare no significant correlation was found. There was a trend of foaling rate decreasing in mares older than 11 years. The highest number of successively registered foalings with 10 live born foals was observed on 2 individual samples. The greatest number of foalings occurred in April (30.9%), whilst there was no foaling in October. The genders were 50.6% male and 49.4% female foals. The incidence ...
The effect of selected factors on the length of gestation period in Silesian mares
The aim of the study was to determine the average length of gestation and its variation in a population of Silesian mares bred during a period of 55 years (1945-2000) in national studs and private farms in southern Poland. Considered was the sex of foals, season, month and year of birth, environmental conditions (national or private breeding centres), breeding history of a mare (number of foals born) and influence of the preceding reproductive period. Gestation period in Silesian mares lasted on average 338.66 days ±13.57 and ranged from 299 (the shortest) to 386 (the longest) days. Gestations lasting from 311 to 356 days were considered normal for the breed. Gestations resulting in a birth of a colt lasted one day longer (339.23±13.44 days compared to 338.19±13.60 days for fillies). Gestations from the autumn reproductive period (October-December), when photoperiods become shorter, were the shortest, whereas gestations from the late spring season (April-June), when photoperiods become longer, were the longest (329.82±10.25 and 341.14±13.87 days, respectively). Significant differences were also found in the length of gestations that ended in particular months: the shortest gestations ended in October (327.45 days ±12.24 days), while the longest in May (342.19±14.19 days). The analysis of the years of foaling, grouped in ten-year periods, showed that the shortest gestations occurred before 1960 (335.41±13.87 days), whereas the longest between 1961 and 1970 (339.64±15.15 days). A slow decrease was observed in the length of gestation in subsequent ten-year periods. Mean gestation period in mares from national studs lasted 5 days longer than that in mares from private breeding centres (334.79±11.21 and 339.60±13.92 days, respectively). The number of foalings did not
Bulgarian Journal of Agricultural Science, 2019
Vlaeva, R., Lukanova, N., Dimitrov, S. & Georgieva, S. (2019) Reproductive parameters of Thoroughbred mares reared in the national stud farm “Kabiyuk” in Bulgaria. Bulg. J. Anim. Sci., 25 (Suppl. 3), 116–119 The reproductive parameters of 51 Thoroughbred mares were studied during the period 1997-2010. A total number of 270 oestrus and reproductive cycles were included in the analysis. Thoroughbred horses are only allowed to mate naturally by traditional hand method. As a source of information was used the zootechnical documentation of the national stud farm. It was established that the reproductive traits subject to the recent study varied in wide ranges interval of foal heat (11.18±2.4031.00±19.92 days) and foaling-to-conception (13.00±3.00-57.00±29.69 days), number of oestrus cycles (1.16±0.38-1.87±1.28), mating of mares (2.80±0.83-3.89±2.40) and total born foals (2-20) per year, duration of oestrus (21.00±2.51-26.00±7.07 days) and heat (3.00±2.22-5.09±1.95 days). The positive cor...
Genetic study of gestation length in andalusian and arabian mares
Animal Reproduction Science, 2006
The length of gestation in Andalusian, or Spanish Purebred (SPB) and Arabian (AB) mares reared in Spain was analysed, based on 766 spontaneous full-term deliveries appertaining to 141 mares of SPB breed and 72 mares of AB breed in 31 breeding seasons. The data were obtained from the Yeguada Militar de Jerez de la Frontera stud farm in Cádiz, Spain. The mean length of gestation was of 336.8 ± 0.48 days in the SPB mares and 340.3 ± 0.63 days in AB mares. To assess the accurate prediction of time of birth the potential effect of a number of factors was investigated. The influences of the breed, mare, month and year of mating, age of the mother, number of births and sex of the foal were statistically significant. The factor have the greatest influence over the gestation length was the mare itself, with a correlation among consecutive births of around 0.4. The effect of inbreeding, both of the mare and foal, was negligible. Gestation length shortened as the breeding season progressed: in both breeds, a delay of 1 month in mating corresponded to a decrease of 3 days in the gestation length. According to our results, gestation length decrease as the mare gets older, with the shortest gestation periods when the mare is 10-12 years old, and from this point on, it slowly increases. The gestation period shortens as the 4th or 5th birth approaches, and then gets progressively longer. The range of variation in gestation length due to the number of births to the mare is of 2.9 days for the AB mares, and 2.2 days for SPB mares. The heritability for the gestation length for AB and the SPB breeds was 0.2, with a repeatability of 0.36 and 0.37, for SPB and AB breeds, respectively. With the data from both breeds, and using a classical approach, the response to selection was estimated if mares with extreme gestation lengths were culled, i.e. lengths which are under 310 days, or over 360 days. According to our results, in the case of * Corresponding author. this value would decrease from 2 to 39%.
Equine Veterinary Journal, 2012
Although low birthweight is a risk factor for neonatal illness, the impact of high birthweight on the health of foals and mares, and on the foals' long-term athletic capability, is unknown. Objectives: To investigate whether: 1) foals that are excessively heavy are associated with an increased prevalence of maternal illness in the first month post partum and reproductive dysfunction in the following season; 2) excessively light or heavy foals are at an increased risk of illness in the first month of life; and 3) birthweight is associated with racing success. Methods: Veterinary records from 230 Thoroughbred mares and 409 foalings were reviewed. Data relating to foaling, foal and mare health during the first month post partum and subsequent breeding efficiency were extracted. Foals' racing records were obtained and the association between birthweight and these outcomes examined. Results: Mares with heavy foals had a higher prevalence of minor nonreproductive problems than those with light and average foals. Compared to average foals, placental weight was lower in the light group and higher in the heavy group. Light foals took longer to stand, nurse and pass meconium, whereas gestation period and duration of Stage 2 parturition were longer in heavy foals. Heavy foals were at increased risk of nonseptic musculoskeletal conditions and conformational defects. Birthweight was not associated with racing outcomes. Conclusions: High birthweight was associated with increased prevalence of neonatal musculoskeletal conditions but birthweight did not have a major impact on mares' health and reproductive efficiency, or foals' racing success. Potential relevance: These data add to the understanding of the impact of birthweight on short-and long-term health outcomes in mares and foals.
Factors Affecting Gestation Length in Heavy Draft Mares
Journal of Equine Veterinary Science, 2013
The purpose of this study was to examine the factors affecting gestation length in 209 foalings from 65 heavy draft horses by multiple linear regression analysis. The objective variable was gestation length, and the explanatory variables were stud farm, year foaled, month foaled, age of mare, parity of mare, last gestation length, foal gender, and some meteorological parameters (the mean values of prepartum 10 days: maximum temperature, minimum temperature, average barometric pressure, and hours of sunshine in a day). The mean gestation length for 209 foalings was 334.9 (standard deviation ¼ 8.3) days, with a range of 313-352 days. Stepwise regression analysis showed that last gestation length and foal gender had significant (P < .01) effects on gestation length. Multiple regression analysis showed that last gestation length (standard partial regression coefficient ¼ 0.54) was more influential on the present gestation length than foal gender (standard partial regression coefficient ¼ 0.22). The present gestation length and the last gestation length were moderately positively correlated (r ¼ 0.56, P < .01). Colt foal (n ¼ 106) pregnancies were significantly (P < .01) longer than fillies (n ¼ 103) (mean AE SEM: colt 337.1 AE 0.7 vs. filly 332.7 AE 0.9). According to our results, last gestation length (mare itself) and foal gender were the main factors affecting gestation length in heavy draft horses. Once several gestation lengths are known, predictions with acceptable accuracy can be made about the gestation length of that mare's following foaling.
Gestational Length and First Postpartum Ovulation of Criollo Mares on a Stud Farm in Southern Brazil
Journal of Equine Veterinary Science, 2007
The Criollo horse industry requires more efforts toward a better understanding of breed characteristics and physiology; few studies have been conducted in Criollo horses to fulfill this demand. Toward this aim, 70 Criollo mares (between 3 and 28 years of age) underwent physiologic evaluation of the length of gestation, occurrence of foal heat, and interval to postpartum ovulation. Gestation length in the 70 mares was 335.6 AE 10.5 days, varying from 312 to 364 days. The mean (AESD) interval from parturition to first ovulation of 42 mares that foaled between September and December of 2005 and 2006 was 19.9 AE 14.0 days. Eighty-three percent of the mares had an interval to foal heat ovulation shorter than 20 days (35/42). The mean (AESD) parturition to ovulation interval of these mares was 14.2 AE 3.0 days.
Acta Veterinaria Scandinavica, 2010
Background: The major horse breeds in Finland are the Finnhorse (FH) and the American Standardbred (SB). The foaling rates of the FH have consistently been lower than those of the SB. During the last years, a decreasing trend in foaling rates of both breeds has been observed. The purpose of this study was to describe and compare the structure of these two mare populations for age, reproductive history and mating type. In addition, changes over the years were studied that could explain the decline in foaling rates. Methods: In Finland, the mating statistics and foaling rates per stallion are published yearly by Suomen Hippos, which is the Finnish trotting and breeding association authorized by the EU. The studied material was the electronic breeding data of Suomen Hippos in 1991-2005 which contained 69 180 cases (one mare bred in one year with one stallion), 20 168 mares, 2 230 stallions and 5 397 stud managers. The effect of mare age and type, mating type and changes during the study period were examined separately for FH and SB using SAS 9.1 for descriptive statistical analyses (frequencies, percentages, means, standard deviations and confidence intervals). The outcome of the last mating per season (foal or not) was used in the calculation of the foaling rates. Results: The FH mares were on average one year older and belonged to the older age groups more often than the SB mares. Ageing decreased foaling rates and even more in FH; the foaling rates were the following: young FH 68.6 and SB 72.1%, middle-aged FH 66.1 and SB 71.9%, ageing FH 61.2 and SB 68.4%, and very old FH 52.8 and SB 61.8%. The foaled mares were more frequent in the SB (45%) than in the FH (37%), but the barren and rested mares were more common in the FH. Natural mating was more commonly practiced in the FH as compared to the SB. The foaling rates decreased from 1991 to 2005 in SB from 75.1 to 65.9% and in FH from 66.5 to 60.8%. For both breeds, the proportion of young mares decreased and the proportion of very old mares increased over the years. Similarly, the proportion of foaled mares in both breeds decreased and the proportion of barren mares increased during the study period. In both breeds, insemination (AI) by transported cooled semen increased, diminishing the on-site AI in the SB and the natural mating in the FH. Conclusions: The results of this study suggest that mare age and type and mating type all affect foaling rates and that the structural differences in the mare populations can explain differences in the foaling rates between the horse breeds and between the time periods.
Maternal lineage influences performance traits in horses. This is probably caused by differences in mitochondrial DNA (mtDNA) transferred to the offspring via the oocyte. In the present study, we investigated if reproductive traits with high variability—gestation length and fetal sex ratio—are influenced by maternal lineage. Data from 142 Warmblood mares from the Brandenburg State Stud at Neustadt (Dosse), Germany, were available for the study. Mares were grouped according to their maternal lineage. Influences on the reproduction parameters gestation length and sex ratio of offspring were analyzed by simple and multiple analyses of variance. A total of 786 cases were included. From the 142 mares, 119 were assigned to six maternal lineages with n≥10 mares per lineage, and 23 mares belonged to smaller maternal lineages. The mean number of live foals produced per mare was 4.6±3.6 (±SD). Live foal rate was 83.5%. Mean gestation length was 338.5±8.9 days (±SD) with a range of 313 to 370 days. Gestation length was affected by maternal lineage (p<0.001). Gestation length was also significantly influenced by the individual mare, age of the mare, year of breeding, month of breeding and sex of the foal (p<0.05). Of the 640 foals born alive at term, 48% were male and 52% female. Mare age group and maternal lineage significantly influenced the sex ratio of the foals (p<0.05). It is concluded that maternal lineage influences reproductive parameters with high variation such as gestation length and foal sex ratio in horses. In young primiparous and aged mares, the percentage of female offspring is higher than the expected 1:1 ratio.
Some aspects of peripartum, neonate and foal heat in mini pony mares
Pferdeheilkunde Equine Medicine, 2010
Physiological aspects of the peripartum period are well known in the Thoroughbred breed. The aim of this study was to establish some physiological parameters of the miniature mare and foal during the same period. Nine Brazilian Pony breed mares mean age 7.5 years old were used. Parameters investigated were: length of gestation; time for placenta deliverance; time for umbilical cord rupture; time for the neonate to stand; time to present suckling reflex; time that the foal took to nurse; time for meconium elimination. Foals height and weight were also measured. Mares were examined by transrectal palpation and ultrasonography from the day following parturition to the 6th day after the second postpartum ovulation, to record follicular development and the onset and duration of foal heat. 7 mares had live foals, and 2 had dystocia (28.5%). Gestational length was 328.3 ± 12.5 days. All births occurred between 01:17 and 04:50 a.m. Umbilical cord took 3.2 ± 2.3 min to rupture, and placentae were delivered mostly at 34.2 ± 6.3 min after parturition, weighing an average of 1.36 ± 0.1 kg. The foals stood up in 19.2 ± 9.9 min and showed suckling reflex in 13.8 ± 9.8 min. First nursing occurred at 69.6 ± 36.9 min; and meconium elimination at 73 ± 50.5 min after birth. Foals' mean height was 58.5 ± 5.07 cm and weight was 14.8 ± 12.1 kg. The first postpartum ovulation occurred 18.6 ± 9.9 days after parturition. Most of the observed parameters show a difference from data existing on normal size mares. However, more studies are needed to assess all the parameters concerning the foal and the minia ture mare's puerperium.