SummaryThe aim of the present study was to evaluate the effect of prepartum artificial photoperiod on pregnancy length and reproductive performance in mares. The study included 145 Thoroughbred mares with age between 4 and 23 years. The mares were submitted to a 15 hour light/9 hour dark photoperiod/day (10W/m 2 ) during different lengths of time before foaling, constituting the following groups: <30: less than 30 days of artificial photoperiod; 30-45: from 30 to 45 days of artificial photoperiod; 46-60: from 46 to 60 days of artificial photoperiod; >60: more than 60 days of artificial photoperiod. In the moment of delivery, mares were classified according to body condition score (crescent range from 1 to 5) and, when necessary, submitted to surgical repair of the vulva within 30 minutes. Mating occurred when a follicle larger than 40 mm was detected, associated with decrease of uterine edema. Twin pregnancies were reduced manually. The number of days in which mares were submitted to artificial photoperiod influenced significantly the anoestrus rate postpartum (p=0.033), as well as the interval between parturition and the first ovulation (p=0.019). Mares submitted to a larger artificial photoperiod showed anoestrus postpartum rate significantly smaller than that observed in mares submitted to artificial photoperiod of less than 30 days (>60 -0%; <30 -16.7%). Parturition-ovulation interval was significantly shorter in mares submitted to artificial photoperiod for more than 30 days (p<0.001). Body condition was influenced by photoperiod. Treatment groups submitted to artificial photoperiod for more than 45 days presented better body condition than that submitted for less than 30 days. The body condition influenced anoestrus postpartum rate (p=0.07) and parturition-ovulation interval (p=0.073). Comparing only mares with body condition score 4 (n=81), a reduction in parturition-ovulation interval in mares submitted to a longer artificial photoperiod was seen (p=0.072). Pregnancy length was not influenced (p=0.077) by the length of photoperiod. There was no influence either on pregnancy rate in foal heat (p>0.1), or on embryo death rate (p>0.1), or on number of cycles per pregnancy rate (p=0.798). It was concluded that the use of a 15-hour light/9 hour dark photoperiod/day (10W/m 2 ) during at least 60 days before delivery decreases significantly the incidence of anoestrus postpartum. The use of this photoperiod for more than 30 days decreases parturition-ovulation interval. There is no influence either on pregnancy rate during foal heat, or on embryo death rate, or on number of cycles per pregnancy. Keywords:equine, artificial photoperiod, postpartum, body condition Einfluss eines künstlichen Lichtregimes auf die Gestationsdauer und den postpartalen Reproduktionserfolg bei Stuten

The present study aimed to verify (a) if the presence of fluid in uterine lumen during foal-heat was related to the post-breeding presence of fluid; (b) if treating mares with fluid accumulation during foal-heat (b1) decreased the incidence of post-breeding fluid accumulation and (b2) improved pregnancy rates during foal-heat; and (c) if post-breeding treatments improved pregnancy rates in mares with post-breeding uterine fluid accumulation. One hundred and sixty two Thoroughbred mares with ages from 4 to 23 years were studied. Fifty-seven mares presented fluid during heat and 35.1% of them retained fluid after ovulation. This result was superior (p<0.05) to that found in mares that did not retain fluid during heat (n=73; 15.1%). Treatments with oxytocics in mares retaining fluid during heat neither decreased the incidence of postbreeding fluid, nor improved pregnancy rates, in comparison to not treated mares. Uterine flushes performed 36-48 h after breeding in mares with post-breeding fluid accumulation (n=31) did not provide satisfactory pregnancy rates (48.4%), results being significantly inferior (p<0.05) than those observed in mares without post-breeding uterine fluid accumulation (n=99; 74.7%). It was concluded that mares that show uterine fluid accumulation during foal-heat also present a larger incidence of post-breeding fluid accumulation. It was also observed that treatments with oxytocics in mares presenting fluid during foal-heat neither decrease the incidence of post-breeding fluid accumulation, nor improve pregnancy rates. Uterine flushes performed 36-48 h after breeding in mares with uterine fluid after foal-heat ovulation do not improve pregnancy rates. Einfluss einer intrauterinenFlüssigkeitsakkumulation vor und nach der ersten postpartalen Ovulation auf die Trächtigkeitsrate bei Stuten Die vorliegende Arbeit diente der Klärung folgender Fragen: a.) Besteht ein Zusammenhang zwischen einer intrauterinen Flüssigkeitsakkumulation in der Fohlenrosse und einer solchen nach der Belegung? b.) Führt eine Behandlung solcher flüssigkeitsbelasteten Stuten in der Fohlenrosse b1.) zu einer Reduktion nach der folgenden Belegung und b2.) zu einer positiven Beeinflussung der Trächtigkeitsrate bei Belegung in der Fohlenrosse? c.) Beeinflusst eine Behandlung flüssigkeitsbelasteter Stuten nach der Belegung zu einer Verbesserung der Trächtigkeitsrate? Untersucht wurden 162 Vollblutzuchtstuten im Alter zwischen 4 und 23 Jahren. 57 Patientinnen zeigten in der Fohlenrosse bereits eine präovulatorische intrauterine Flüssigkeitsakkumulation, die bei 35,1% nach der Ovulation persistierte. Demgegenüber entwickelten von den 73 präovulatorisch nicht betroffenen Stuten 11 (15,1%) eine postovulatorische intrauterine Flüssigkeitsakkumulation, d.h. bereits präovulatorisch vorbelastete Stuten sind signifikant häufiger (p<0,05) betroffen. Eine Behandlung mit Oxytocinpräparaten der flüssigkeitsbelasteten Stuten beeinflusste weder das Auftreten einer solchen nach Belegung noch die Trächtigkeitsrate, verglichen mit den nicht behandel...

O objetivo do presente trabalho foi determinar: (1) se o acúmulo de fluido intra-uterino (FIU) durante o cio do potro pode influenciar a freqüência de acúmulo de FIU após a cobertura; (2) se o acúmulo de FIU durante o cio do potro pode prejudicar as taxas de prenhez; (3) se tratamentos em éguas com acúmulo de FIU durante o cio do potro diminui a incidência de FIU após a cobertura e melhora os índices de prenhez; (4) se éguas não cobertas no cio do potro apresentam maiores índices de prenhez no cio subseqüente e (5) se lavagens uterinas realizadas após a cobertura podem melhorar as taxas de prenhez de éguas cobertas no cio do potro. Foram utilizadas éguas Puro Sangue de Corrida com idades variando entre 3 e 23 anos. Todos os partos foram controlados e, quando necessário, foi realizada vulvoplastia. A partir do 5 o dia pósparto, as éguas foram examinadas através de palpação retal e ultra-sonografia, em intervalos inferiores a 48 horas, para verificar o crescimento folicular, o grau de edema uterino e a presença de FIU. As éguas foram cobertas quando um folículo com diâmetro maior que 40mm foi detectado, associado com a redução do edema uterino. Novo exame foi realizado 36 a 48 horas após a cobertura para confirmar a ovulação e verificar a condição uterina. Todas as éguas que apresentaram FIU 36 a 48 horas após a cobertura foram submetidas a lavagens uterinas seguidas de uma aplicação endovenosa de 20UI de ocitocina. O diagnóstico de gestação foi realizado 12 a 14 dias após a ovulação. Perdas gestacionais observadas entre o primeiro diagnóstico de gestação e os 42 dias de prenhez foram consideradas como morte embrionária (ME). Quatro experimentos foram realizados. De cinqüenta e sete éguas que apresentaram FIU durante o cio do potro, 35,1% apresentaram FIU após a ovulação, resultado superior (p<0,05) ao verificado em éguas que não retiveram FIU durante o cio do potro (n=73; 15,1%). Os índices de prenhez das éguas com presença de FIU durante o cio do potro não diferiram significativamente (p>0,05) dos das éguas que não apresentaram FIU. Tratamentos com ocitócicos em éguas com FIU durante o cio do potro não diminuíram a incidência de FIU pós-cobertura, nem melhoraram os índices de prenhez, em comparação com as éguas não tratadas. As taxas de prenhez aos 14 dias em éguas que apresentaram FIU durante o cio do potro não diferiram significativamente (p>0,05) entre as éguas não tratadas, as cobertas no segundo cio e as submetidas a lavagens 6 a 8h após a cobertura. Entretanto, observou-se diferença significativa (p<0,05) nos índices de prenhez aos 42 dias entre as éguas submetidas a lavagens 6 a 8h após a cobertura e aquelas não tratadas. A prenhez obtida em éguas com FIU pós-cobertura (n=31), submetidas a lavagens uterinas realizadas entre 36 e 48 horas após a cobertura, foi significativamente inferior (p<0,05) à verificada nas éguas sem FIU após a cobertura (n=99; 74,7%). Os resultados obtidos permitem concluir que: ocorre uma maior incidência de FIU após a cobertura no cio do potro em éguas apresentando FIU durante o ci...