Nutrition: Flax oil can help improve fatty acid profile for sows and litters

Wednesday, December 2, 2009

Research suggests that supplementing sow diets with flax seed or flax seed oil during the last trimester of gestation can increase the fatty acid composition of plasma and milk of sows, and of piglet tissues

by JANICE MURPHY

Flax has long been recognized for its medicinal properties. In the past, it has been used to alleviate constipation in sows at farrowing, but there is growing interest in the effects of the omega-3 fatty acids. These fatty acids alter immune and inflammation responses which, when coupled with the hormonal changes that occur during pregnancy, have a positive effect on sow productivity and the health of the piglets.

In addition, research has shown that feeding flax seed to pregnant and lactating sows can increase piglet growth rate. However, the mechanisms by which this occurs remain a bit of a puzzle. Further research to document what changes in fatty acids occur may provide a key piece of that puzzle.

To date, most of the research on feeding polyunsaturated fatty acids (PUFAs) has focused on feeding fish oils to change the omega-3/omega-6 ratio in sows and their piglets. While flax seed is an excellent source of polyunsaturated oil in the form of alpha-linolenic acid, only two studies have been reported on pregnant sows. One study noted an increase in linolenic acid in the plasma and fat tissue of sows when feeding 1.75 per cent flax seed oil, while the other reported an increase in omega-3 fatty acids in the serum of neonatal piglets when feeding 10 per cent flax seed.

To explore this area further, researchers at Agriculture and Agri-Food Canada's Swine and Dairy Research Centre in Sherbrooke, Que., set out to establish detailed fatty acid profiles before and after dietary supplementation with flax in the plasma of pregnant sows, the carcasses and brains of neonatal piglets, and sow milk in early and late lactation. Their objective was to demonstrate the effects of feeding flax as seed, meal or oil on these fatty acid profiles.

Sixty second and third parity Yorkshire × Landrace sows were fed one of four diets from 68 days of gestation until 21 days of lactation. This timeframe was chosen since it encompasses the last third of gestation, when the majority of fetal growth occurs.

The diets administered were; control without flax, 10 per cent flax seed (FS) supplementation, 6.5 per cent flax seed meal (FSM) supplementation, and 3.5 per cent flax seed oil (FSO) supplementation. Sows were limit fed during gestation and intakes were adjusted to ensure that daily energy and protein intake was similar across all treatment groups; sows were fed ad libitum during lactation. Fat composition of flax seed, meal and oil is provided in Table 1.

Throughout lactation, fresh feed was given twice daily. Sows received one kilogram of feed on the day of farrowing (Day 1) and three kilograms on Day 2. Five kilograms were fed ad libitum from Day 4 onward.

Jugular blood samples were taken from sows on days 62 and 110 of gestation and on days 2 and 21 of lactation. Milk samples were taken on days 3 and 20 of lactation. Fatty acid profiles were established in plasma and milk. In addition, one male piglet from each litter was slaughtered on Day 1 to establish fatty acid profiles in carcass and brain tissue.

The data showed that the flax treatments did not affect sow weight differences from Day 62 to Day 110 of gestation, as well as from Day 2 to Day 22 of lactation. There was, however, a tendency for backfat thickness to be greater in FS compared with FSO sows on days 62 and 110 of gestation, with this difference proving to be significant on Day 2 of lactation, but not on Day 21.

On Day 110 of gestation, the plasma results indicated that sows fed FS and FSO had significantly lower levels of saturated fatty acids (SFAs), more PUFAs, more omega-3 fatty acids and a lower ratio of omega-6 to omega-3 than sows fed FSM. These significant differences were also evident on Day 21 of lactation, when a lower level of monounsaturated fatty acids (MUFAs) was also evident.

Milk from sows fed FS and FSO showed significantly higher levels of omega-3 fatty acids and a lower omega-6/omega-3 ratio on days 3 and 20 of lactation. This was accompanied by significantly lower SFA and MUFA but higher PUFA concentrations on Day 20. Carcass and brain tissues from the corresponding newborn piglets also exhibited significantly higher omega-3 fatty acids and a lower ratio of omega-6 to omega-3 when compared to piglets farrowed by sows on the FSM treatment.

These results identified important changes in the fatty acid composition of plasma and milk of sows, and of piglet tissues that can be realized through supplementation of sow diets with flax seed or flax seed oil during the last trimester of gestation. Interestingly, the availability of fatty acids appears to be similar, regardless of whether the flax is fed as seed or oil. These differences were not observed, however, when flax was included in the diet as flax seed meal, suggesting that the oil component of flax is the key to bringing about these changes.

As is often the case, the results suggest that further research is warranted. The researchers suggest that the next logical step is a study to determine how the beneficial impacts of these changes in fatty acid levels might be manifested on the production parameters of sows and their litters. BP

Sources: C. Farmer and H. V. Petit. 2009. Effects of dietary supplementation with different forms of flax in late-gestation and lactation on fatty acid profiles in sows and their piglets.  J. Anim. Sci. 87:2600-2613. Flax Council of Canada. 2009. http://www.flaxcouncil.ca/. Reese, D. 2003. Omega-3 Fatty Acids and Swine Reproduction - A Review. Nebraska Swine Reports. http:// digitalcommons.unl.edu/coopext_swine/66/.

Janice Murphy is a former Ontario agriculture ministry swine nutritionist who now lives and works in Prince Edward Island.