Supplement types in the springtime

David Colbourne, Teagasc, Ballyhaise Given the present low milk price, feeding meal should be minimised cut out as soon as possible. Typically, 1kg meal gives an extra litre milk; if meal costs 21 c/kg (€210 per tonne) and milk price is 21 c/l, feeding meal is break even at best. If you are short on grass, consider the following: • Concentrates based on digestible fibre sources (eg pulps) compliment grass well while cereal diets should be minimised on grass • The response to maize silage is similar to concentrates in spring but poor in the autumn. The labour input and associated costs are higher with forage maize. • Loose dung implies that cows are digesting the pasture effectively and the retention time in the rumen is low. Low milk fat, alongside loose dungs, is an indication of a lack of fibre in the diet and there may be a response to offering cows a fibre source - stemmy baled silage, hay or straw. Buying concentrate feeds 1. Shop around - there is considerable variation in concentrate/ ingredient prices. Prices are still falling, but low prices indicate poorer ingredients. 2. The energy and protein quality of the compound feed is more critical than the individual ingredients that make up the compound feed. Always look for an energy value for the ration. 3. Target protein levels in the concentrate in April/ May: silage by night = 16% CP; on/off grazing with no silage in the diet = 14% CP; outdoors full-time for first rotation = 14% CP; main grazing season and autumn = 6-12% CP. Straight citrus pulp is suitable in spring for cows yielding 20-23 litres and at grass full-time (don"t forget the minerals). 4. Ensure that the mineral inclusion level matches the feeding rate for the concentrate feed. At a feeding rate of 2kg, 4kg and 6kg calmag inclusion rate should be 3%, 1.5% and 1%, respectively. If your meal has Cal Mag to feed at 2kg and you decide to feed 4kg because the weather is wet, cows may start scouring. For pasture dusting, apply 210g of calmag/cow/day. Using coarse rations, it is important that minerals do not separate out from the ingredients, a binder such as molasses should be used. Remember high molasses levels in coarse rations will cause bridging in bins. Grass Tetany Prevention The biggest danger period for grass tetany (magnesium deficiency) is from turn out to grass until about mid May but many farmers find it necessary to take preventative measures throughout most of the grazing season especially in cold wet weather. The most obvious losses are when cows go down or die but more widespread losses occur from a reduction in milk yields due to a sub-clinical level of magnesium deficiency. Application of potash in spring increases magnesium deficiency and should be avoided. The application of spring cattle slurry has a similar effect, as it is high in potash. In early spring, cows require a minimum of 30-40gms of magnesium or the equivalent of 2-2½ oz of calcined magnesite every day for full protection. Unlike many other minerals, cows cannot store sufficient magnesium in the body so very careful management is required to ensure that every cow in the herd is getting her daily requirements during danger periods. Sometimes a few different preventative methods should be used at the same time. As a precaution, farmers should inspect their cows regularly, have injectable magnesium available and call a veterinary surgeon if symptoms such as nervousness or un-co-ordination are noticed. The following preventative methods have been found successful at farm level when operated properly. The four main preventative methods for dairy cows are; meal feeding, pasture dusting, water treatment and boluses. Preventative Methods 1. Meal Feeding The surest method of prevention is to feed 2-2½ oz of Calmag per cow per day in the meals. Problems can arise if some cows refuse meals when sufficient grass becomes available. Make sure that your level of magnesium in the ration matches your feeding rate when cows go to grass. Compounders will include different levels of Cal Mag for different feeding rates. Too much magnesium will scour cows. When concentrates are being reduced, Cal Mag levels have to be increased to provide at least 2oz of Cal Mag per day. Most compounders now make a ration with high levels of trace elements and also contain sufficient Cal Mag for 1 to 3kgs per day feeding rate. This ration often called summer/ grazing ration, has beneficial effects on breeding. This is a wiser choice than feeding low levels of a ration containing high Cal Mag only as cows will often benefit from the trace elements especially Iodine. In early Spring when cows are on different levels of ration due to varying weather conditions it is difficult to ensure the proper level of magnesium through meal feeding so other methods such as water treatment or pasture dusting may also be used. Sweet Calmag is also available which is far more palatable and can be fed in very little carrier. Three ounces per cow per day costs about 6c and gives good protection. 2. Pasture Dressing Spreading 6kg (14 lbs) of fine powdered calcined magnesite per acre or 200g/cow/day is an effective and cheap method of preventing grass tetany if carried out properly. It can be spread for five days in advance of grazing on damp pasture. This method of grass tetany prevention is not widely practised but it deserves much more attention from farmers especially in late spring. A light pasture dressing can be useful as an additional precaution against fatalities even if other preventative methods are being used, eg if some cows give up eating meals. 3. Drinking Water Treatment There are several soluble magnesium salt products on the market for mixing through drinking water. Generally, at best, these supply 20 gms magnesium but can give satisfactory protection if managed carefully. Trace elements especially Iodine are added to some of these products. They can be fed through inline dispensers or preferably through trough dispensers. Some of these products can be more conveniently bought in powder form and dissolved on the farm. Alternative Methods Molasses/Magnesium Mixes and blocks Commercial liquid products and blocks are available. As with any free choice system this is not as reliable as the aforementioned. Another free choice system of feeding magnesium with molasses is to mix equal parts by weight of molasses and calcined magnesite. The mixture has to be stirred three times daily and requires a lot of attention to ensure all animals get their requirements and could not be generally recommended. Blocks are most suitable for suckler cows that are not on concentrates. Cost Comparison of Mineral Options at Grass Cost c/ cow/ day Ration (1kg carrier) 20-22 Ration (2kg carrier) 40-44 Pasture dusting magnesium (€16.50/ 25kg bag) c. 15 Drinking water eg flowmag Mg only 17 Mg + TE (I and Se) 21 TE only (I, Cu, Se, Zn) 13 Mg + TE (I, Se, Cu, Co, Zn) 28 Aquadyne (I) 4.5