Sheep Milk: Milk functionality

Our research found that sheep milk proteins are more easily digested than cow milk proteins and sheep milk activates intestinal genes involved in gut health, growth and in keeping pathogens out of our system. Sheep milk was found to have more beneficial effects on bone structure than cow milk.

What are the nutritional characteristics of sheep milk from around the year that supports animal management, product development, marketing, and regulatory/compliance purposes?

Although differences in milk composition between species have been known for a long time, prior to the start of this research programme there was no data available on the detailed composition of New Zealand sheep milk. We did not know:

• If the composition of New Zealand sheep milk was different to that of milk from other countries
• If/how much the composition and flavour changed throughout the milking season
• How much the composition varied between different New Zealand producers
• If the composition and flavour changed upon processing and storage, and if so: how?

A series of in vitro and rat feeding studies were undertaken in this programme. These provided some base information with which to evaluate potential health benefits of sheep milk consumption.

The following attributes were tested:

• Potential to alter immune function
• Digestibility
• Mineral accumulation and growth and intake
• Bone growth and strength

This work provided significant insights.

Digested sheep milk increased tumor necrosis factor-alpha (a proinflammatory cytokine) in cultured human immune cells, while digested cow milk increased interleukin-10. These results suggest that digested sheep milk may have some different bioactive effects in fighting infections compared to cow milk.

As a result of their distinct structural characteristics, sheep milk fats were more digestible than cow milk fats, potentially providing better nutrition for those at risk such as premature infants and the elderly.

When investigating mineral provision by sheep milk higher concentrations of dimethyl sulfone, a metabolite with inflammatory and antioxidant properties used to manage arthritic and rheumatic pain, were detected.

The nutrient-dense nature of sheep milk demonstrated that a lower intake of sheep milk is required to supply essential minerals to the diet.

Micro-computer tomography, mechanical bending tests and inductively coupled plasma mass spectrometry were used to investigate bone structure and health. Higher trabecular bone surface density and trabecular bone surface to volume ratio suggests that the structural integrity of bone may be positively affected by the consumption of sheep milk.