Factors affecting gestational length in the Mangalarga Paulista breed

Abstract

The Mangalarga Paulista is a Brazilian horse breed that originated from a cross between Andalusian and Alter Real horses, and despite its national importance, no data exist regarding their gestational length. This study was conducted to determine the variation in gestation length and the influence of factors such as the sex of the foal, maternal age and parity, stallion and mating period. Retrospectively, data from 208 gestations of Mangalarga Paulista foals located in Piracaia, SP, Brazil, during the period from 1991 to 2012 were analyzed. The mean gestational length was 343.08 ± 0.66 days, with a range between 317 and 404 days. Gestation of mares carrying colts had a tendency to be longer than mares carrying fillies. Maternal parity significantly affected gestational length, with longer gestation for primiparous mares until the third gestation, shorter pregnancies between 4th and 8th gestation, and longer thereafter. Regarding mating period, mares that were mated at the end of the breeding season (January and February) had shorter pregnancies (P < 0.05). These results are of significant clinical and economic relevance for the equine industry, so that the monitoring of gestation and parturition can be performed effectively.

Are mule pregnancies really longer than equine pregnancies? Comparison between mule and equine pregnancies

“…Interestingly, the fact that the Equine group had a longer GL than the Mule group is opposite of what has been reported anecdotally and what has been hypothesized here. Our group reported similar GL for Mangalarga Paulista breed mares, with 208 equine pregnancies of Mangalarga Paulista mares having a median GL of 343.1 ± 0.7 days (range 317-404 days) (Ferreira et al, 2016). However, the GL of the Equine and Mule groups was nevertheless shorter than of pregnancies of jennies with donkey semen (Galisteo & Perez-Marin, 2010).…”

“…Studies show opposing results, with a significant difference in the GL depending on the gender of the foal. Gestations resulting in colts were longer (Christmann et al, ; Davies Morel et al, ; McCue & Ferris, ; Valera et al, ), while others showed no difference in GL between foal gender (Campitelli et al, ; Ferreira et al, ; Galisteo & Perez‐Marin, ). Interestingly, our results showed that pregnancies in both groups that resulted in females were longer, although this finding was not statistically significant, differing from the notion that male offspring would result in longer GL.…”

“…More specifically, the GL in mares pregnant with equines is extremely variable. Reports state a mean of 335.6 ± 10.5 days for Criollo mares (range 312–364 days) (Winter, Rubin, Corte, & Silva, ); 336.7 ± 0.5 days (range 290–361 days) for Spanish Purebred (Valera et al, ); 340.3 ± 0.6 days (range 306–360 days) for Arabian mares (Valera et al, ); 341.0 ± 0.3 days (range 307–381 days) for Thoroughbreds, Quarter Horses and other breeds (McCue & Ferris, ); 341.7 ± 10.7 days (range 300–390 days) for Warmblood mares (Christmann, Sieme, Martinsson, & Distl, ); 343.1 ± 0.7 (range 317–404 days) for Mangalarga Paulista mares (Ferreira et al, ); and 344.1 ± 0.5 days (range 315–388 days) for Thoroughbred mares (Davies Morel, Newcombe, & Holland, ).…”

“…Variables such as mare, month of foaling, foal sex, breed, age of mare, year of conception and month of conception have been reported to influence GL (Davies Morel et al, 2002;McCue & Ferris, 2012;Valera et al, 2006). Studies have reported mixed results to whether the foal sex has an effect on GL, with some reporting longer intervals for colts (Davies Morel et al, 2002;McCue & Ferris, 2012;Valera et al, 2006), while no difference of GL in relation to foal gender has also been reported (Campitelli, Carenzi, & Verga, 1982;Ferreira et al, 2016;Galisteo & Perez-Marin, 2010). To the best of our knowledge, no study has investigated and compared the gestational length of mares pregnant with equine or mule foals with exact ovulation dates while also investigating effect of foal sex.…”

Equine gestational length and location: is there more that the research could be telling us?

“…Yet another study identified 4 years as the age at which mares’ longest gestation occurred, after which it decreased, as did fertility levels . Several studies have reported differences between primiparous and multiparous mares . Langlois and Blouin found that mares had a longer gestation if they had not foaled the previous year …”