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Thinking boar feeding

by 5m Editor
19 February 2007, at 12:00am

By Mick Hazzledine, Premier Nutrition and published in PIC's Pig Genomics Journal - A quick look in the scientific literature quickly reveals a mass of papers on the reproduction of pigs.

Look more closely and you will see a slight bias. Despite our scientific advancements, the boar still has a part to play – looking at the literature you wouldn’t believe it! So what do we know about feeding the boar?

Firstly, sperm have relatively huge energy requirements for motility. The more active an organ, the more important is antioxidant function, as this "wraps-up" harmful free radicals preventing tissue damage. Also, we need to ensure the correct fuel for the sperm motility. Secondly, if we look at the fatty acid analysis of sperm this is also unique, as it is one of the richest sources of Omega 3 fatty acids seen in nature. Pigs, in common with most mammals (including humans) and birds, largely rely on their feed for Omega 3 fats. But for active males it is increasingly appreciated that a deficiency of Omega 3 fats may limit performance. Additionally, antioxidant function is again important as Omega 3 fats easily become rancid.

This simplistic evaluation gives us a number of areas where nutrition may influence boar performance. Antioxidant function, for example, would include vitamin E, vitamin C, vitamin A, zinc and selenium. Carnitine is a vitamin-like substance that is involved in moving energy in and out of cells, so may be useful in the "fuel" debate. And maybe feeding oils rich in Omega 3 fats, such as fish, might also be useful.

In fact, all the above have been shown in recent research to improve boar fertility. Selenium is a metal and is essential as part of the seleno-proteins. These are involved in an antioxidant capacity, in thyroid function and immunity, and in sperm formation and function. Typically 0.25mg/kg of sodium selenite is added to sow feed. There is a background level of around 0.1 mg/kg from cereals and soya (much reduced in recent years because of soil depletion).

Selenium yeast provides a more bioavailable form of selenium and will be licensed for pig feeds later this year. The following Polish trial (see Table 1) looked at the influence of selenium level and vitamin E on sperm production and morphology. A total of 40 boars were used in the trial and feeds were offered from 22-110kg. The higher selenium level was achieved with selenium yeast.

The use of a higher vitamin E and organic selenium in feeds for rearing boars significantly increased sperm concentration and total number of spermatozoa and reduced sperm defects. There is also data to show that sows may be deficient in selenium, particularly in later parities. An addition of 0.1mg Se/kg of organic selenium in sow feeds and 0.2mg/kg in boar feeds is worthy of consideration to minimise the risk of selenium deficiencies. For an additional 0.1mg Se from yeast, the cost implication is about 50p/tonne.

Finally, selenium deficiency in humans is increasingly linked to prostate and bowel cancer. Guess which country has one of the lowest levels of plasma selenium? The UK!!


December 2006