The greatest inhibitor of performance in sheep is insufficient energy, and this results from improper feeding. Thus, in order to get the most out of your sheep, it is vital that you follow a good feeding regime that contains all the most important elements of a sheep’s diet, including protein, water, energy, minerals and vitamins. These can all be found in essential feeds such as pasture, hay, grain and silage[1]. Sheep will require more or less supplements of different elements depending on their age, size, pregnancy and environment. Supplementation is very important when pastures lack energy or protein. It also lessons the pressure on grazing pastures so that they grow as well as possible in the dry season[2].
The best way to calculate suitable feeding rates is to perform regular body condition scoring of your flock. A guide to body scoring created by Oregon University can be seen below.
Table 1: Body Condition Scoring in Sheep[3]
What follows are some brief notes to give you a general idea on how to ensure your sheep have all their essential dietary requirements.
PROTEIN When it comes to protein in sheep, quantity is more important than quality. Sheep are ruminants and are able to use protein and urea that occur naturally in their diets, coming from oilseeds such as cottonseed, soybeans, sunflower seeds, linseed and peanuts, which contain up to 50% protein. Legume hays, such as lucerne, can also contain up to 20% protein, and are effective in providing enough protein when fed as part of a complete ration. Providing small amounts of a supplement rich in protein (20 to 50 grams per head per day) will improve the utilisation of dry pastures, provided the amount of dry pasture is non-limiting and is of fair quality – at least 50 to 55% digestibility. However, over-providing protein-rich supplements, i.e. more than 100g/head/day will lead to sheep preferring the supplementary feed to the pasture, and this will reduce pasture utilisation[4]. Lambs younger than 2 months or that are limit-fed, should not be fed urea. Older than this, urea should not make up more than 1/3 of the protein in the sheep’s diet (330g/1kg). Large quantities of urea fed in a short time can be toxic. [5] Ewes in late pregnancy have higher protein requirements and their diet should contain more than 15% crude protein.
ENERGY If the quality of a pasture is less than 50% digestible, the energy for sheep maintenance is limited, and feeding protein will not allow you to better utilise your dry pastures. Rather, a feed with high energy will need to be provided. You should also remember that the energy requirements of sheep will change with feed quality, average daily walking distance to find feed and current nutritional status. For ewes, it will also depend on stage of production, i.e. whether they are pregnant, dry or lactating. Ewes are perhaps the most important part of the flock, as they determine the rate of flock growth and production, and so plenty of effort must be put into managing ewes’ energy needs, which are the most variable. They will mildly increase during early pregnancy, and then rise quickly in the final 50 days before lambing. Peak lactation will happen at 25 days, and this is another big demand on energy.
MINERALS AND VITAMINS Most of the 13 different minerals required by sheep are met by normal grazing and feeding. The minerals that most need to be supplemented are salt (sodium chloride) and phosphorous. If sheep are low on salt, they will have stunted growth, lower milk production and will not absorb as much food and water. Salt added to mixed feed should make up 0.3% of the complete diet or 1% of the concentration portion. A good guide for providing supplemental salt is to give range ewes 11g each per day. Loose salt provided free-choice is better than providing salt blocks as sheep will more likely bite the salt blocks than lick them, which will break their teeth or cause them to wear away prematurely. As well as sodium chloride (NaCl) the loose salt can contain traces of other elements such as iodine (I), cobalt (Co), iron (Fe), magnesium (Mg), Zinc (Zn)[6] and phosphorous (P). High levels of phosphorous are not found in hay or pastures, but may be found in grains. The leaves of plants will contain high levels of calcium, with legumes generally containing more calcium than grasses. If sheep are only fed cereal grains, e.g. corn silage, then they should be given ground limestone at a rate of about 9 to 14g/head/day[7]. Sheep require all fat-soluble vitamins, enough of which are generally found in the forage and feed. However, in the dry/winter period, sheep may not get enough vitamin A, and sheep kept indoors may also become deficient in vitamin D. So these vitamins will need to be supplemented using. Vitamins A, D and E can be supplemented in powder form or as vitamins encapsulated in wheat starch. Vitamin D may also be found in good quality hay[8]. B vitamins are made in the rumen and so do not require supplementation except in very unusual circumstances.
WATER Whilst everyone knows that water is essential for every living creature, in sheep, the quality of water is just as important. Sheep will not consume dirty or stagnant water. However, if the water is clean and of high enough quality, sheep will usually consume up to three times as much water as dry matter. Without water, feed intake will decrease and sheep condition may decline. Water intake will increase with increased consumption of protein, minerals and dry matter, as well as when temperatures are higher and during late gestation and lactation. It is important the sheep have enough water available to them during these periods.
[1] https://www.nation.co.ke/business/seedsofgold/Five-key-things-to-keep-in-mind-when-feeding-sheep/2301238-3073866-xtno40z/index.html [2] https://www.agric.wa.gov.au/feeding-nutrition/supplementary-feeding-and-feed-budgeting-sheep?nopaging=1 [3] Body condition scoring of sheep, Oregon State University, 1994. [4] https://www.agric.wa.gov.au/feeding-nutrition/supplementary-feeding-and-feed-budgeting-sheep?nopaging=1 [5] https://www.nation.co.ke/business/seedsofgold/Five-key-things-to-keep-in-mind-when-feeding-sheep/2301238-3073866-xtno40z/index.html [6] http://www.ag.auburn.edu/~chibale/an16sheepfeeding.pdf [7] https://www.msdvetmanual.com/management-and-nutrition/nutrition-sheep/nutritional-requirements-of-sheep [8] http://www.vitfoss.com/media/22176/mineralsandvitaminsforsheepandlambs_vitfoss.pdf