# Comparative Analysis of Signature Lipid Structures in Canine and Feline Milk Compared with Bovine and Caprine Milk

## TL;DR

This study compares the lipid structures in dog and cat milk to cow and goat milk, finding significant differences that could help create better milk replacers for puppies and kittens.

## Contribution

The study identifies unique lipid structures and biomarkers in canine and feline milk that could guide the development of species-specific milk replacers.

## Key findings

- Canine and feline milk have significantly higher total and phospholipid content than bovine and caprine milk.
- Canine and feline milk contain higher levels of unsaturated fatty acids and specific long-chain polyunsaturated fatty acids like DHA and AA.
- Over 60% of palmitic acid in canine and feline milk is located at the sn−2 position of triacylglycerols, similar to human milk.

## Abstract

Canine and feline milk are vital for the early development of offspring, yet their lipid profiles differ significantly from the bovine and caprine milk commonly used in milk replacers. This study systematically compared the lipid composition of milk from dogs, cats, cows, and goats. The results showed that the concentrations of total lipids and phospholipids in canine and feline milk were significantly higher than those in bovine and caprine milk. Additionally, canine and feline milk contained higher levels of unsaturated fatty acids and were rich in docosahexaenoic acid and arachidonic acid. Notably, we also observed that a large proportion of palmitic acid was located at the sn−2 position of triacylglycerols in canine and feline milk, a structural feature that may influence digestion. Through lipidomic analysis, more than 2700 lipid molecules were identified, and several specific molecules that can serve as characteristic markers for canine and feline milk were discovered. These findings provide key scientific evidence for the precise development of specialized milk replacers that meet the nutritional needs of puppies and kittens, supporting their healthy growth.

This study systematically compared the lipidomes of canine, feline, bovine, and caprine milk. Feline milk contained the highest total lipid content (110.83 mg/mL), significantly exceeding that of canine (81.52 mg/mL), caprine (40.27 mg/mL), and bovine milk (36.25 mg/mL). The phospholipid content in both canine (0.97 mg/mL) and feline milk (0.90 mg/mL) was approximately three times higher than that in bovine and caprine milk (approximately 0.30 mg/mL). Compared to bovine and caprine milk (approximately 30%), canine and feline milk had markedly higher proportions of unsaturated fatty acids (approximately 70%) and were enriched with functional long-chain polyunsaturated fatty acids, including arachidonic acid and docosahexaenoic acid. A distinctive feature was that over 60% of palmitic acid was esterified at the sn−2 position of triacylglycerols in canine and feline milk, a structural similarity shared with human milk. Lipidomic analysis identified 2708 lipid molecules across the four milk types, revealing several triacylglycerol species as potential species-specific biomarkers. These findings provide a concrete scientific basis for developing precisely formulated milk replacers that meet the specific nutritional requirements of puppies and kittens.