Horses and donkeys differ phenotypically and karyotypically, although they can interbreed freely. Eight Standardbred mares and nine Amiata donkey jennies were included in the study. Semen was collected from two horses and two donkey stallions of proven fertility. A first pregnancy diagnosis was performed on day 10 after ovulation and repeated every day until embryo detection or until day 16. Irrespectively of the sire species, pregnancy rates in horse females (20/30, 66.7%) were significantly higher than in donkey females (19/70, 27.1%) (p < 0.05), while horse and donkey males did not affect pregnancy rates. Comparing overall intraspecific and interspecific AI, pregnancy rates were 25/37 (67.6%) and 14/63 (22.2%), respectively (p = 0.0001). The lowest pregnancy rate was obtained when inseminating jennies with horse stallion semen (8/49, 16.3%). No statistical differences were found when comparing embryo diameters, day at first pregnancy diagnosis, or in vitro embryo morphological quality among groups. In this study, much poorer results were obtained with jennies than with mares. Interspecific AI resulted in lower pregnancy rates than intraspecific Al, and AI to produce hinny hybrids resulted in the lowest pregnancy rate. Further studies are required to better understand the mechanism involved in such different outcomes in relation to intra- and interspecific breeding in domestic equids.

Despite their inability to reproduce naturally, mules can host embryos and be surrogate dams. The aim of this investigation was to increase our knowledge of the qualitative composition of mule’s milk and its variations throughout the whole lactation period—namely, from 6 h after foaling to 180 days in milk (DIM). Milk was obtained from a mule dam that had foaled after receiving a mule embryo transfer. For each sample, the gross, mineral, and fatty acid composition was evaluated. The average quality of the mule milk was as follows: protein 1.97 g 100 mL⁻¹, fat 0.90 g 100 mL⁻¹, and ash 0.39 g 100 mL⁻¹. Saturated fatty acids made up, on average, 50.00 g 100 g⁻¹ of fat. Monounsaturated and polyunsaturated fatty acids made up half of the total fatty acid content (31.80 g 100 g⁻¹ and 18.2 g 100 g⁻¹ of fat, respectively). Linoleic acid and linolenic acid were the main polyunsaturated fatty acids in the milk. The milk composition changed throughout lactation. Dry matter, protein, fat, and ash decreased significantly from early lactation (6 h to 14 DIM). The n3 polyunsaturated fatty acids decreased at the end of lactation. The changes in milk composition throughout lactation are probably due to adaptations to the growth requirements of the foal.

A case of presumptive allantois or amniotic hydrops of the fetal membranes was diagnosed in a young Intracytoplasmic Sperm Injection (ICSI) derived embryo recipient. Hydrops is a rare condition and treatment is usually focused on saving the mare. This case report describes the successful management of hydrops of the fetal membranes diagnosed in an Anglo-Argentine mare at 316 days of gestation, which resulted in a live foal. The mare was treated with broad-spectrum antibiotic therapy (30 mg/kg twice a day sulfadiazine-trimethoprim per os), an anti-inflammatory (flunixin meglumine 1.1 mg/kg once a day Intravenously (IV)), plus progestin’s (altrenogest 0.44 mg/kg once daily per os) at day 328 of pregnancy, an immature foal was delivered and was immediately treated with antibiotics (ampicillin 10-20 mg/kg three times a day IV and amikacin 25-30 mg/kg once a day IV), antiacid therapy (ranitidine 1.5-2 mg/kg IV twice a day), as well as hyperimmune plasma and fluid therapy. Oxygen therapy was introduced while the foal was asleep. A commercial IgG blood test confirmed the passage of immunoglobulins. The histological architecture of the placenta revealed that both the amnion and allantois cavities were involved. This report describes one of the few hydrops pregnancy cases reported with a positive outcome for both the mare and foal. Early suspicion was found to be crucial for the positive outcome, enabling rapid hospitalization for the monitoring, treatment, and supportive care of both the mare and foal.