Successful Induction of Lactation in a Barren Thoroughbred Mare: Growth of a Foal Raised on Induced Lactation and the Corresponding Maternal Hormone Profiles

Abstract

ABSTRAcT. The purpose of this study was to demonstrate that a barren parous Thoroughbred mare with lactation induced by hormonal treatment can be introduced to an orphan foal at the same farm and that the mare can become pregnant after the end of the hormonal treatment. An additional purpose was to investigate the changes in the plasma concentrations of prolactin, estradiol-17β, progesterone, folliclestimulating hormone, and luteinizing hormone before, during, and after hormonal treatment. The difference in body weight between the adopted foal and the control foals, which were at the same farm and raised by their natural mothers, was 17 kg at 24 weeks old, when the foals were weaned. However, the adopted foal and the control foals had almost the same weight at 35 weeks old and later. The first ovulation after hormonal treatment was confirmed 10 days after the end of hormonal treatment and then the normal estrous cycle resumed. Furthermore, the changes in plasma progesterone, estradiol-17β, follicle-stimulating hormone, and luteinizing hormone showed regular patterns after the first ovulation. Conception was confirmed in the fifth ovulation. Meanwhile, another study demonstrated that conception was confirmed in the first ovulation after hormonal treatment. The present study is the first to demonstrate the hormonal profiles during and after induction of lactation in a Thoroughbred mare. This approach is useful for solving the economic and epidemic problems of introducing a nurse mare to an orphan foal. KEY WORDS: hormonal treatment, horse, induction of lactation.

Assessment of Prolactin and Quantitative Milk Production After Induction of Lactation in Barren Jennies (Equus asinus): A Pilot Study

“…The results support the hypothesis of previous [1,2] and recent [3] studies, which showed that the sudden increase of circulating PRL concentrations, as observed in healthy pregnancy of pony and Thoroughbred mares, could be the trigger for the onset of lactation also in Ragusana mares.…”

“…Circulating PRL concentrations obtained in jennies (Equus asinus) are in agreement with data obtained in control mares (Equus caballus) but were lower than those observed during sulpiride treatment, with superimposable milk production [3,20].…”

“…The highest CV values in pluriparous and nulliparous jennies confirmed large individual variations observed in various breed categories of control and/or sulpiride-treated mares (E. caballus) [3,20], including stallions and geldings [4,11]; moreover, it is quite difficult to compare sporadic data from various authors because of different physiological conditions and analytical methods were applied (equine PRL [ePRL]) determined by radioimmunoassay: the intra-assay and interassay CVs and sensitivity were 13.7%, 8.7%, and 0.1 ng/mL, respectively [6]; the intraassay CV and sensitivity were 10.2% and 0.4 ng/mL, respectively [33]; the intra-assay and interassay CVs were 4.3% and 8.7%, respectively [3]; the intra-assay and interassay CVs and sensitivity were 7%, 12%, and 0.2 ng/mL, respectively [5,21,34]; the intra-assay and interassay CVs and sensitivity were 3.4%, 10.3%, and 0.25 ng/mL, respectively [11].…”

“…Prolactin (PRL) is the main hormone involved in inducing lactation in equines, and its sudden increase in healthy gestation could be the trigger for the onset of lactation [1][2][3]. Prolactin secretory pattern is also involved in response to physical [4] and emotional [5] stimuli, with a temporal relationship [6,7] in equines, and significant changes in PRL levels have been observed in response to excitement and stress in stallions and geldings [5].…”

“…Dopamine antagonists such as sulpiride are used experimentally to induce cyclicity during winter transition in mares [12][13][14], with an increase of PRL secretion [13,15,16] and milk secretion after treatment [17][18][19]. It has been recognized that milk production after pharmaceutical induction of lactation in mares can offer practical and economical advantages [3,17,20]. Though, in mares, the changes in plasma PRL in response to injection of sulpiride were greater than for thyrotropin-releasing hormone treatment [21].…”