Natural Algae Boosts Health Benefits of Lamb

Lambs involved in the study

At a glance

• Lambs at DPI Rutherglen were fed different diets, including ryegrass/clover hay cubes and some with an algae supplement.
• Lambs fed the algae supplement absorbed much higher levels of Omega-3 fatty acids.
• Lambs fed the algae supplement gained more weight per kg of feed consumed, saving on feed costs.

Feeding lambs as little as 20g of algae supplement per day for eight weeks boosted Omega-3 levels in meat 240 per cent compared with lambs consuming a ryegrass-clover hay diet.

Omega-3 fatty acids are essential fats in the human diet playing an important role in growth and brain development. According to the Omega-3 Centre, a centre of excellence set up to examine Omega-3 benefits, the fats are credited with preventing cardiovascular disease, diabetes, other inflammatory diseases and improving mental health.

In a world-first study carried out at DPI Rutherglen, scientists investigated the impact of feeding lambs an algae supplement to determine the effect on live weight gain and meat quality.

Some background

In Australia, about two-thirds of total health expenditure relates to disease, according to the Australian Institute of Health and Welfare. The institute believes it is likely that part of this expenditure is due to the health impact of poor diets.

DPI scientist Dr Eric Ponnampalam said traditionally, lambs grazing green pastures had higher rates of Omega-3 than when fed formulated diets or rations.

“Green pastures and flax seeds are rich sources of a precursor fatty acid called alpha-linolenic acid (ALA), which is absorbed during digestion and may convert in the body tissues to Omega-3 long chain fatty acids,” he said.

Dr Ponnampalam said long chain fatty acids include eicosapentaenoic acid   (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) and these   are the forms of Omega-3 most important for health.

“In turn that’s changing the fatty acid composition of muscle tissue as these feeds are low in Omega-3 fatty acids.”

He said the conversion rate of ALA to long chain fatty acids is low when compared with direct dietary supplements such as algae rich in long chain fatty acids.

Conversion to long chain fatty acids is important because these provide significantly higher health benefits.

The Australian New Zealand Food Standards Code — Standard 1.2.8 — requires that food must have 30mg of long chain Omega-3 fatty acids or 200mg of ALA per 100g of food to be considered a ‘source’ of Omega-3. If it has 60mg of long chain fatty acids it’s a ‘good source’.

A previous experiment conducted at DPI found that lambs grazed on perennial pastures had been shown to have 34mg of long chain Omega-3 fatty acids per 100g of meat and those on annual pasture with various supplements 29–32mg.

While it has been shown that lamb has the highest Omega-3 of all red meats, there is an opportunity to further increase these levels.

Dr Ponnampalam began studying the dietary enrichment of Omega-3 fatty acids in lambs during the mid-1990s using fish meal and oilseed by-products.

He said the recent development of using algae in absorbing CO2, reducing methane emissions from livestock and in medicine, had renewed the interest of using algae to improve the nutritional characteristics of meat.

The study

Four groups of nine month old crossbred ewe lambs took part in the experiment over an eight week period between March and July 2010.

The control group consumed ryegrass/clover hay cubes of moderate energy and protein content. The algae group consumed the control diet plus 20g of a dried algae supplement. The two other non-control groups consumed a diet of the same hay cubes plus either 134g of flaxseed, which is also a source of Omega-3, or a combination of flaxseed (117g) and algae (19g) (see Table 1).

The lambs fed algae recorded an impressive 85mg of Omega-3 per 100g of meat, far higher than the control group and the flaxseed group, which recorded just 25mg and still significantly higher than the flaxseed/algae group.

Dr Ponnampalam believes future work could lift lamb meat to over 90mg long chain Omega-3 fatty acids per 100g of meat. He said although lamb may remain lower in Omega-3 than fish, it also offered other benefits such as iron, zinc, B vitamins and protein.

Even in this experiment he said the levels of Omega-3 fatty acids in lamb were competitive.

“Our research showed that a 135g serve of algae supplemented lamb provides 129mg of long chain Omega-3 fatty acids, including EPAD, DPA and DHA.

Table 1:  Daily average dry matter intake and muscle long chain Omega-3 fatty acid concentration of lambs fed four dietary treatments

Top: Algae; middle: flax, bottom: hay cubes

“According to Australian Nutrient Reference Values, this is more than the daily recommended amount for women and 80 per cent of what’s required for men to prevent deficiency.”

Currently, it’s estimated Australians eat 170mg a day of Omega-3 fatty acids, but this is primarily from alpha-linolenic acid (ALA), a parent Omega-3 fatty acid, which does not offer the same health benefits as the long chain Omega-3 (EPA, DPA, DHA) fatty acids.

Dr Ponnampalam said in the current study flaxseed increased muscle ALA content, but this did not lift long chain Omega-3 levels in muscle any more than lambs consuming ryegrass-clover hay diet, which is indicative of low conversion efficiency.

Finding algae

Dr Ponnampalam said the dietary benefits of algae had been recognised for some time, but were only just being introduced to animal and human foods.

“Algae has been in use in human products. For example, it’s in medicines and pharmaceuticals. Now it’s slowly being introduced into human food supplies through sweets such as ice cream and milk shakes as well as thickeners and gelling agents used in soups and jellies. It’s also used in sushi.

“Algae also contain powerful antioxidants, are a rich source of vitamins and trace minerals and provide high quality proteins.”

Dr Ponnampalam said both animals and people are expected to consume more foods made from algae in future.

When Dr Ponnampalam began the study, algae had to be imported from the United States. Now there is an algae plant in Queensland, and two underway, one in Gippsland and another in NSW.

DPI Fisheries Victoria has also set up its own algal production facility as a vital component for their shellfish hatchery at DPI Queenscliff.

The environmental benefits

Apart from its dietary benefits, algae is being embraced for its ability in the   capture and conversion of CO2 emissions into sustainable production, biofuels   and feed for the livestock industry to potentially reduce methane emissions from ruminants.

While other studies have looked at this more specifically, Dr Ponnampalam said his own project clearly indicated algae’s environmental attributes.

This means the animals consumed less fibre, one of the triggers for methane emissions.

Dr Ponnampalam said the results indicated that the lambs fed algae were more efficient in converting feed and this was captured in the carcase weight.

He said future experiments would look at using different algae strains and attempt to determine the ideal levels to be offered and the length of time they need to be fed to get the best response.

In addition, there is also a critical need to determine whether the algae used as a supplement affects the eating quality of the lamb meat.

The bottom line

Being able to produce lamb that has high levels of Omega-3 fatty acids may increase the demand for lamb due to its health attributes, according to Dr Ponnampalam.

He also hopes higher Omega-3 fatty acid levels may one day translate to a direct economic benefit to individual farmers and producers apart from the social and environmental benefits they could provide.

Earlier studies from other countries suggest that increasing polyunsaturated fatty acids such as Omega-3 in muscle foods may affect the taste through lipid oxidation.

This occurs when these unsaturated fats react with oxygen to develop components that produce undesirable flavours when cooked or heated.

He said based on results from previous DPI research, the taste and flavour of the meat was not expected to change provided vitamin E levels in the muscle tissue were maintained, although no taste testing has been conducted on algae fed lambs as yet.

Vitamin E acts as an antioxidant in living animal tissues and meat to prevent oxidation of lipids (fatty acids) and haem pigments (iron).

He said feed costs are also likely to be lower as a result of feeding sheep high energy supplements such as algae and this would also be the subject of future research.

Ultimately, Dr Ponnampalam said the research was just a start.

“These results are just the beginning. We will continue to investigate the best forages and supplements to increase productivity and optimum lamb nutrition for high quality lamb meat,” he said.