<p><span style="font-size: 10pt;"><strong><span style="line-height: 107%;"></span></strong></span></p>
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<p><span style="font-size: 10pt;"><span style="line-height: 107%;"><span style="font-size: 10pt; font-family: arial,helvetica,sans-serif;"><em><span style="line-height: 115%;"><em>The article is written by Dr. Dag Austbø at the Norwegian University of Life Sciences institution. Dr. Dag Austbø and Dr. Knut Hove are two of the key people behind the development of PC-Horse. Their scientific work and international networks contribute to the continued development of PC-Horse and to secure that our calculations are based on established scientific data.</em></span></em></span></span></span></p>
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<p><span style="font-size: 10pt;"><strong><span style="line-height: 107%;"></span><span style="line-height: 107%; background-color: #ffffff;">Vitamin E and selenium function jointly in protecting body cells from oxidation-induced damage. Low levels of selenium can partly be replaced by higher levels <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">of</span> vitamin E and vice versa, but they can never totally replace <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">each other</span>. Selenium deficiency is a constant threat where soils are low in selenium, as in Scandinavia and the British Isles. </span></strong></span></p>
<p><img src="images-joomla/stories/seasons/selen-vitaminE.jpg" alt="selen-vitaminE" /></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong>Biological oxidation<br /></strong>In order to extract the chemical energy bound in organic nutrients like fat and carbohydrate, all animals use oxygen from the air in a process called biological oxidation. Carbon dioxide and water are formed as waste products, and the liberated energy is used in the body <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">for, among other things, muscle contraction and growth</span>. During the process of biological oxidation, free radicals - highly reactive agents - are also produced as a side effect. If these radicals are not destroyed, they will damage living cells, notably their lipids and proteins. Unsaturated fatty acids, a major component of all cell membranes, are particularly susceptible to oxidative damage.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong>Antioxidants<br /></strong>Vitamin E and selenium act as <em>antioxidants</em> by preventing this damage to cell components which <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">will always</span> occur <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">as part of oxidative</span> processes needed to release the energy in our food.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><span style="text-decoration: underline;">Vitamin E</span> (alfa-tocopherol) is a <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">fat-soluble</span> vitamin. <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">It acts on</span> the lipid-rich membranes of the cells, where it helps to prevent free radicals from damaging these cell structures.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><span style="text-decoration: underline;">Selenium</span> is a water soluble mineral that is needed in very small quantities (see below). Selenium is part of the intracellular enzyme glutathione peroxidase, which helps to prevent the formation of free radicals and <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">to destroy</span> oxidized lipids (peroxides) in the cells.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;">The requirements for vitamin E and selenium that are given in the following tables are according <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">to NRC-2007</span> recommendations.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong><span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">Vitamin E requirements<br /></span></strong>The <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">requirements</span> for vitamin E <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">below</span> are <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">based on</span> NRC-2007*. The amount of vitamin E is given as international units (IU) and the requirements are as IU per kg body weight per day. 1 IU is equivalent to 1 mg of the vitamin.</span></p>
<p><span style="font-size: 10pt;"><em>Table 1. Daily requirements for vitamin E, IU per kg body weight.</em></span></p>
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<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong><span style="color: white;">Type of horse</span></strong></span></p>
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<td style="width: 252.6pt; border-width: 1pt 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #70ad47; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong><span style="color: white;">Vitamin E requirement, IU per kg body weight</span></strong></span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="198">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong>Idle horses (maintenance) </strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;">1.0</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="198">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong>Horses in training</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;">1.6 – 2.0 </span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="198">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong>Pregnant mares</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;">1.0</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="198">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong>Lactating mares</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;">2.0</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="198">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong>Young growing horses</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;">2.0</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="198">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;"><strong>Stallions in the breeding season</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="253">
<p style="margin-bottom: 0.0001pt; line-height: normal;"><span style="font-size: 10pt;">1.6</span></p>
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<p><span style="font-size: 10pt; background-color: #ffffff;">Vitamin E is relatively <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">non-toxic</span> and moderate overdosing will not cause any negative effects.</span></p>
<p><span style="font-size: 10pt;"></span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong><span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">Selenium requirements</span></strong></span></p>
<p><span style="font-size: 10pt;">NRC 2007* gives the requirement for selenium as milligrams per kg (mg/kg) of dry matter in the horse’s daily ration.</span></p>
<p><span style="font-size: 10pt;"><em>Table 2. Daily requirements for selenium, mg per kg dry matter in ration.</em></span></p>
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<td style="width: 198.2pt; border-width: 1pt medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #70ad47; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong><span style="color: white;">Type of horse</span></strong></span></p>
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<td style="width: 252.6pt; border-width: 1pt 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #70ad47; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;"><strong><span style="color: white;">Selenium requirement, mg per kg dry matter</span></strong></span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong>Idle horses (maintenance) </strong></span></p>
</td>
<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;">0.1</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong>Horses in training</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;">0.1</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong>Pregnant mares</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;">0.1</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong>Lactating mares</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;">0.1</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong>Young growing horses</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; background: none repeat scroll 0% 0% #e2efd9; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;">0.1</span></p>
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<td style="width: 198.2pt; border-right: 1pt none; border-width: medium 1pt 1pt; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="198">
<p><span style="font-size: 10pt;"><strong>Stallions in the breeding season</strong></span></p>
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<td style="width: 252.6pt; border-width: medium 1pt 1pt medium; border-style: none; border-color: -moz-use-text-color; padding: 0cm 5.4pt;" valign="top" width="253">
<p><span style="font-size: 10pt;">0.1</span></p>
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<p><span style="font-size: 10pt;"><em>Dry m<span style="background-color: #ffffff;">atter in rations for different types of horses are calculated using assumed feed intakes of 2.5% of body weight (BW) for heavy and very heavy exercise, for lactating mares and for growing horses; 2.25% of BW for moderate exercise; and 2.0% of BW for all other classes.</span></em></span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;">Selenium is highly toxic and overdosing <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">must</span> be avoided.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong>Sources of vitamin E<br /></strong>Fresh, growing forage contains 100 – 400 IU of vitamin E per kg DM. The amount of vitamin E decreases as the plant matures. Grass hay and haylage contain from 20 – 60 IU per kg DM and the amount decreases during storage. For oats and barley typical values are around 20 IU per kg DM.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;">Concentrate mixtures for horses are commonly fortified with vitamin E. Typical concentrations in commercial concentrates are in the range 400 – 600 IU per kg.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong>Sources of selenium<br /></strong>Forage and grains grown in the UK and Scandinavia are typically low to very low in selenium. This means that horse owners must rely <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">on concentrate</span> mixtures and mineral supplements to <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">cover requirements</span>. Concentrate mixtures for horses are commonly supplemented with 0.4 – 0.6 mg selenium per kg.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong>What happens when selenium and vitamin E are deficient in the diet<br /></strong>Selenium or vitamin E deficiencies are uncommon in horses other than foals from birth to one <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">month</span> of age. They occur as a result of inadequate selenium intake by the mare during pregnancy, or inadequate selenium and/or vitamin E intake during lactation. The most common selenium and vitamin E deficiency disease in foals is white muscle disease. Mild deficiency of either selenium or vitamin E may lead to a decrease in the immune response to infectious diseases <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">and, with selenium,</span> slower growth.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;"><strong>How can you find out <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">whether</span> the vitamin E and selenium content of your horse’s diet is adequate?<br /></strong>To know the vitamin E and selenium content of <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">a diet</span>, you have to do some calculations. <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">With PC-Horse this can become a quick</span> and easy operation. PC-Horse calculates your horse’s individual requirements for vitamin E and selenium from the information you have <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">already</span> entered into the program. The contents of vitamin E and selenium are included for all feeds in the feed <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">list. You can instantly</span> see how well the requirements are covered as you compose the horse’s daily ration <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">using the PC-Horse program</span>. <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">The program will both warn you</span> when the diet is deficient, and <span style="background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; background-clip: border-box; background-origin: padding-box; background-size: auto auto;">also</span> when there is a potentially toxic surplus of Selenium in the daily ration.</span></p>
<p><span style="font-size: 10pt; background-color: #ffffff;">*NRC 2007. Nutrient Requirements of Horses, sixth revised edition. National Academic Press, Washington, D.C., USA.</span></p>
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<p><strong>What does this mean in practice?</strong><br />Daily intake of roughage varies based on feed quality, production classes, individual appetite and each individual's place in the herd hierarchy. This means that we must observe horses in a herd closely and make corrections to the feed offered each individual at night-time or early morning to avoid some individuals growing too fat or too thin.</p>
<p><a href="index.php/en/manual/demos"><strong><strong>Watch a video on using PC-Horse</strong></strong></a></p>
<p><a href="index.php/en/news/new-feedlist"><strong>See what feeds are included in the program´s ready-to-go feed list</strong></a></p>
<p><a href="index.php/en/articles/topic-of-the-month/other-topics"><strong>Previous month articles can be found here</strong></a></p>
<p><em><strong>Give us topic suggestions for future monthly articles</strong></em></p>
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