Interspecies variation in milk composition among horses, zebras and asses (Perissodactyla: Equidae).

The study analysed the milk composition of six different types of wild and domestic equid species including onager, mountain zebra, plains zebra, Przewalski horse, ass and pony. The results indicated that all these species produce milk with similar composition and the domestic horse could be a suitable model to study equid lactation.

Study Design and Findings

• The researchers collected milk samples from four wild equid species which are onager, mountain zebra, plains zebra, and Przewalski horse, and two domesticated equid species which are ass and pony.
• These samples were analysed at mid to late lactation periods. The research found that the milk from all these species had a similar composition – they contained approximately 10-12% total solids, 1-2% fat, 1.6-1.8% true protein, 6-7% lactose, 0.3-0.5% ash, 0.08-0.12% calcium, 0.04-0.07% phosphorus and a calculated energy content of 2.0-2.4 kJ/g.
• Milk samples which were collected in the initial two weeks after birth showed elevated levels of total solids and protein, and some exhibited reduced lactose levels. However, no significant trends could be observed in milk composition during mid to late lactation periods which is around 1-12 months post partum.

Implications of the Study

• The research concluded that these closely related species produce milk that is nearly identical in terms of gross composition.
• This uniformity implies that the domestic horse could serve as a representative model for studying equid lactation. As such, it could be used in future research to gain more comprehensive insights into equid lactation and improve our understanding of equid milk composition, nutrition, and potential uses.
• These findings also have implications for equid conservation strategies. If the milk compositions are similar across various species, it can also be inferred that their nutritional needs are similar, which can help in planning better diets and supplementation regimes for these species in conservation programs.