hinny

Background: Compared to horses and ponies, donkeys have increased degradation of dietary fiber. The longer total mean retention time of feed in the donkey gut has been proposed to be the basis of this, because of the increased time available for feed to be acted upon by enzymes and the gut microbiota. However, differences in terms of microbial concentrations and/or community composition in the hindgut may also underpin the increased degradation of fiber in donkeys. Therefore, a study was conducted to assess if differences existed between the fecal microbiota of pony, donkey and hybrids derived from them (i.e. pony × donkey) when fed the same forage diet. 

Results: Fecal community composition of prokaryotes and anaerobic fungi significantly differed between equine types. The relative abundance of two bacterial genera was significantly higher in donkey compared to both pony and pony x donkey: Lachnoclostridium 10 and ‘probable genus 10’ from the Lachnospiraceae family. The relative abundance of Piromyces was significantly lower in donkey compared to pony × donkey, with pony not significantly differing from either of the other equine types. In contrast, the uncultivated genus SK3 was only found in donkey (4 of the 8 animals). The number of anaerobic fungal OTUs was also significantly higher in donkey than in the other two equine types, with no significant differences found between pony and pony × donkey. Equine types did not significantly differ with respect to prokaryotic alpha diversity, fecal dry matter content or fecal concentrations of bacteria, archaea and anaerobic fungi.

Conclusions: Donkey fecal microbiota differed from that of both pony and pony × donkey. These differences related to a higher relative abundance and diversity of taxa with known, or speculated, roles in plant material degradation. These findings are consistent with the previously reported increased fiber degradation in donkeys compared to ponies, and suggest that the hindgut microbiota plays a role. This offers novel opportunities for pony and pony × donkey to extract more energy from dietary fiber via microbial mediated strategies. This could potentially decrease the need for energy dense feeds which are a risk factor for gut-mediated disease.

Little scientific information is known regarding mules and even less is known about hinnies. Due to increased popularity of both as recreational animals which are still commonly found as working equids, there is a need for such basic information for practitioners and owners. The purpose of this study was to begin to establish reference ranges for hematological and biochemical parameters of clinically healthy mules and hinnies compared to those of their sires and dams (horses and donkeys of similar genotype, phenotype within species) used for hybrid offspring production. Such information will contribute to our understanding and attempts to improve management and disease diagnosis of hinnies and mules. Eighty-one healthy equids (n = 30 hinnies, 20 mules, 20 donkeys, and 11 horses) were sampled. Clinical data recorded age, gender, BCS, and temperature. Two 10-mL blood samples were collected by venipuncture of the jugular vein, using “vacutainer” plain and EDTA tubes. These samples were analyzed for RBC, PCV, Hb, WBC, platelets, proteins, fatty acids, electrolytes, enzymes, and glucose. Average and standard deviations were calculated. Kruskal-Wallis test was used to test the significant value. Findings were considered to be significant if P ≤ 0.05. When comparing all parameters among four groups of equids, differences were found for temperature, red blood cell lines, white blood cell lines, electrolytes, and enzymes. Differences in mules and hinnies were seen in RBC, WBC, magnesium, bilirubin, creatinine, and AST. The results are constricted to very few known populations of equid hybrids with similar genetics. In this study, hinnies and mules showed results that were closer to those of horses than those of donkeys. Some differences recorded in hinnies may be related to age: RBC, WBC, MCH, MCV, eosinophils, magnesium, total bilirubin, creatinine, and AST. Findings may help establish new, relevant hematological and biochemical parameters which may prevent medical misdiagnosis. Additional research is needed with larger populations of healthy mules and hinnies.

Mules and hinnies are hybrid offspring of donkeys (Equus asinus) and horses (Equus caballus). Little scientific information is known regarding mules and even less is known about hinnies, the reciprocal cross. Conformation standards are in place for horses but currently are not available for equid hybrids or donkeys. Conformation maybe related to functionality and longevity of equids. All animals in this study were of similar genetics (Zamora Leones and Mirandes donkey breeds and Spanish horses) from Toro, Spain and Miranda do Douro, Portugal and used for traction.