A PLANNED APPROACH TO FEEDING THE EWE - A GUIDE TO FEEDING IN LATE PREGNANCY

Transcription

1 Defra ADAS A PLANNED APPROACH TO FEEDING THE EWE - A GUIDE TO FEEDING IN LATE PREGNANCY Adequate nutrition of the ewe during pregnancy is of paramount importance to the survival and viability of all lambs conceived. In the late stages of pregnancy the energy and protein intake of the ewe should be increased to match the ewes increasing requirements for the developing lambs, for udder development and colostrum production. 70 % of foetal growth occurs in the last 6 weeks of pregnancy, during which time rumen capacity and hence food intake is reducing. The consequences of underfeeding in the last two months of pregnancy include: thin ewes twin lamb disease small weak lambs poor supply of colostrum high lamb losses poor milk yield KEY POINTS TO CONSIDER: 1. Body condition scoring At eight weeks before lambing condition score all ewes by placing your hand on the back over the last rib. Feeling for the sharpness of the bones will give a very good guide to the adequacy of previous feeding. Refer to the Defra booklet Condition Scoring of Sheep for guidance. Ewes should then be split in to 3 groups: thin - condition score 2 or less (lowland ewes) or 1.5 or less ( hill/upland ewes) fit - condition score 2.5 to 3.5 (lowland ewes) or 2 to 3 ( hill/upland ewes) fat - condition score 4+ (lowland ewes) or (hill/upland ewes) Ideally all ewes should be fit but genetic variation, age and expected litter size will all affect condition. 2. Pregnancy scanning Pregnancy scanning is a very useful management tool. It allows separation of ewes according to litter size and date of lambing. Rations can then be fed which more closely match the ewes needs, helping you to economise on feed

2 costs, whilst feeding the best diet to your sheep. Ideally scanning should take place at between 50 to 90 days of pregnancy. 3. Forage quality The quantity and quality of forage available for feeding in late pregnancy should be assessed three months before lambing is due to start. If feeding hay or silage a sample should be analysed by a reputable laboratory. The results will guide you or your advisor as to the best supplement to compliment the forage and the levels to feed. Forage analysis Key points to consider: a) D value - A measure of digestibility. This gives a good guide to the maturity of the crop, generally the higher the level the better the quality. Good hay has a D value of 58 to 62 and good silage has a D value 64 to 70. b) Dry matter - Hays should be 84 to 90 % dry matter. Lower than 84 % may indicate a tendency to moulding. Clamp silage should be 25 to 40 % dry matter, any wetter and ewes will struggle to eat enough to meet their needs. Big bale silage should be over 25 %. Very wet forage is difficult to ensile satisfactorily in big bales, and very dry material will have a tendency to moulding. c) Crude protein - usually linked to D value since very mature crops tend to have very low protein. For hay, protein is likely to be between 8 and 14 %. For silage, protein is likely to be between 8 and 20 %. Generally the higher the protein in the forage the lower the level of protein needed in the supplement. d) Silage fermentation characteristics - on most silage analyses you will find information on the fermentation of the crop. As a general rule the wetter the silage the more extensive the fermentation and the more acids produced. High levels of fermentation acids can restrict intakes. ph and ammonia levels also give a guide to the nature of the fermentation. In clamp silages ph (a measure of acidity) tends to be lower i.e. more acid, and below ph 4 intakes can be limited. In big bale silages, since they tend to be drier, acidity is generally not a problem. Ammonia levels above 10 % of the total nitrogen indicate some breakdown of protein to ammonia. High ammonia silages tend to be unpalatable and higher levels of supplement will be required to compensate for this. d) Ash - forage has a natural level of ash, including trace elements and minerals but levels over 10 % indicate soil contamination. Soil contamination is often associated with a poor fermentation and a high risk of listeriosis. Obviously soiled material should not be fed to sheep.

3 Care should be taken to feed only good quality forage in late pregnancy to maximise food intake and avoid nutritional problems 4. Concentrate feed Once forage quality has been established a concentrate feed should be chosen. Home mixes Simple home mixes using cereals, beet pulp and soya bean meal, are both economical and of high feeding value. Example mixes are shown below: kg/tonne 16 % protein 18 % protein Barley Molassed Sugar Beet Feed Soya bean meal Mineral Molasses Both mixes are of high energy (12.9 MJ/kg DM) and have a high quality protein supply. Soya bean meal is the best quality vegetable protein available, although there are several other possible protein sources to choose from. The cereal component of the mixes could be barley, wheat or oats, and the cereal can be left whole when fed with the majority of forages. On high quality silage, rolling of cereals is recommended to avoid too much whole grain passing through the gut undigested. The molasses is added to help carry the finely ground ingredients and reduce dust and provide readily available sugar. The beet pulp is included to add a palatable and highly digestible source of fibre and to aid digestion in the rumen. The mineral is included to provide trace elements, major minerals and vitamins to meet the ewes needs. Special minerals can be made up to suit individual circumstances. Choosing a compound feed The range of compound feeds is huge and there are wide differences in quality and price. As a general rule the better the quality the better the value for money. ADAS advise buying a compound with a minimum of 12 MJ/kg DM. Low energy feeds of 10 to 11 MJ/kg DM will not produce the same results and levels of feeding will need to be higher to compensate. Ask your supplier for a full formulation and specification of the product before buying, and do not be fooled by inappropriate names. A Gold compound may not be the top of the range as you might expect - find out the detail!

4 Specify the protein level needed - 16, 18 or 20% and then look at the ingredients. The level of protein tells you nothing about the quality of the feed - it only tells you the amount of protein. There are good and bad sources of protein so do not be fooled by the protein percentage. Look at the diet formulation and check the sources of energy. Are there any cereals included, barley, wheat, oats, maize? Are there any recognisable byproducts e.g. Maize Gluten, Wheatfeed, Sugar beet pulp? Are there any poor quality ingredients e.g. Oat feed, Olive pulp, Shea nut, Cocoa shells, Coffee residues? Large quantities of these must be avoided. It is important to look at the list of ingredients given on every feed label as this is given in descending order of inclusion. If barley makes up the largest part of the feed then this would be at the top of the list, and if minerals are present in the smallest amount they would be at the bottom of the list. Poor quality ingredients should only appear close to the bottom of the list if they are present in small amounts. As a guide to likely inclusion rates - molasses is normally included at 4 to 8 % of the compound. The table below gives basic detail of energy and protein levels in a range of commonly used feeds: Crude Protein % as fed Metabolisable Energy (MJ/kgDM) Barley Wheat Molassed Sugar Beet Feed Rapeseed Meal Soya bean Meal (Brazilian) Hi-pro soya Maize Gluten Wheatfeed Sunflower (standard) Molasses (cane) Beans If in doubt ask your compounder or an independent consultant for an explanation of the feed and its specification. Compounds with high levels of crude fibre (more than 10 %) or high levels of ash (more than 10 %) should be avoided as these are invariably of low energy. Cheap, low quality feed is false economy since more of it needs to be fed to achieve the same nutrient intake. 5. Blocks and liquid feeds

5 Blocks and liquid feeds can be very useful when feeding in extensive grazing systems. They reduce daily labour requirements and ensure a constant supply of supplementary feeds in difficult conditions. The same rules about quality ingredients apply to compounds and blocks alike. These feeds can also be useful in a lowland situation to provide a constant supply of concentrates for heavily pregnant or thin ewes. 6. Supplementary feeding Space allowances Forage should be available at all times, and fresh forage should be provided daily. This is particularly important when feeding silage. Any rejected forage should be cleared away and discarded or offered to other stock. When forage is available ad-lib allow 6 inches (15 cm) of feed face per ewe. If forage has to be restricted then allow enough room for all ewes to feed at once - i.e. 18 inches (45 cm) per Mule ewe. Fresh clean water should always be available. When feeding concentrates allow 18 inches (45 cm) of trough space per ewe. It is vitally important that all ewes can feed at the same time if they are to stand a chance of getting their fair share. Alternatively feed compound feed on the floor. This avoids the need for troughs and allows ewes to graze the concentrates off the bedding. This gives a slow intake of compound feed and potentially a better digestion. Floor feeding is only suitable if the ground or bedding is clean and dry. If ewes are housed, group sizes should ideally not exceed 50 ewes. Ewes (depending on body weight) should be allowed 11 to 14 sq ft (1.1 to 1.3 m2) bedded area/head. Feeding levels If ewes have been grouped according to expected litter size and body condition then feeding levels will vary. The following tables give guidance on levels of feeding according to litter size. The rations are for 70 kg mule ewes in condition score 3.0. Adjustments according to condition should allow thin ewes expecting twins to be fed as triplets, and fat ewes expecting twins to be fed as singles etc. Ewes should not be fed more than 0.5 kg (1 lb) in one feed. All rations shown assume high quality compound feeds or home mixes with a minimum of 12 MJ/kg DM. Quantities of forage are only given as a guide. a. Silage rations Big bale silage - 64 D value, 10.4 MJ/kg DM, 14 % protein, 35 % DM kg/head/ day

6 Singles Silage 3.0 < ad-lib > 2.8 Compound Twins Silage 3.0 < ad-lib > 2.7 Compound Triplets Silage 3.0 < ad-lib > 2.5 Compound % protein compound or home mix Clamp Silage - 70 D value, 11.0 MJ/kg DM, 18 % protein, 25 % DM kg/head/ day Weeks before lambing Singles Silage 4.5 < ad-lib > 4.0 Compound Twins Silage 4.5 < ad-lib > 3.8 Compound Triplets Silage 4.5 < ad-lib > 3.6 Compound % protein compound or home mix b. Hay rations Average hay MJ/kg DM, 10 % protein kg/head/ day Weeks before lambing Singles Hay 1.1 < ad-lib > 1.0 Compound Twins Hay 1.1 < ad-lib >.9 Compound

7 Triplets Hay 1.1 < ad-lib >.85 Compound % protein compound or home mix c. Straw rations Clean, bright wheat or barley straw kg/head/ day Weeks before lambing Singles Straw < ad-lib > Compound Twins Straw < ad-lib > Compound Triplets Straw < ad-lib > Compound % protein compound or home mix When straw feeding, ewes should be offered clean dry straw every day Rejected stems should be discarded. Allow approximately 1.5 kg of straw per ewe per day. Ewes need to be selective to pull out the more digestible parts of the straw. It is critical that only fit ewes are offered straw-based diets Vitamin E Recent research has shown the benefits of providing extra vitamin E in the diet of the pregnant ewe. The newborn lamb is faster to stand and suckle and there are added benefits of increased live-weight gain. Levels of vitamin E in compound feeds have been increased in recognition of this research and ADAS now recommend a level of 100 to 150 iu vitamin E per kg compound feed. 8. Feeding in early lactation Once ewes have lambed it is important to ensure that all lambs receive adequate colostrum to provide immunity against disease. Lambs need more colostrum than you think - a 4 kg lamb needs over 1.5 pints in its first day of life. To produce plenty of colostrum and milk, ewes need to be maintained on their pre-lambing diet for at least 24 hours or until turn-out. Peak milk yield of

8 the ewe is 3 to 4 weeks post-lambing and to get good lamb growth rates ewes need generous feeding until this time. If grass growth is poor, feeding at prelambing levels of concentrate (to a maximum of 1 kg/head/day) should be continued until grass is at least 4 cm (2 inches) high. Once grass is above this height, feed levels can be reduced, but remember when feeding lush spring grass there is a high risk of staggers, so provide supplementary magnesium.