Planning to hit spring targets

Meeting spring feed requirements of your ewes and their lambs will only be possible if you plan ahead. The first thing to consider is the condition that your ewes started winter. ewes that go into winter in good condition will only require maintenance levels of feed in the first portion of that season; ewes in poor condition will already be playing catch-up.

The feed requirements of ewes increase signifi cantly in the last part of pregnancy, particularly the last six weeks. it is important to meet these requirements to avoid animal health issues in spring, for example milk fever or pregnancy toxaemia. This will ensure vigorous lambs and promote good udder development so that ewes produce adequate levels of colostrum and can feed lambs well.

Feed basics

The energy an animal requires is measured in megajoules of metabolisable energy (MJ Me), and in the last six weeks before lambing a single-bearing ewe's requirements climb from an extra 2.5 MJMe/day (on top of maintenance requirements) to an extra seven MJMe/day at lambing. Good-quality, leafy pasture contains 11-12 MJMe/kg DM, so this means ewes will need around an extra 0.2kg DM/day, rising to an extra 0.6kg DM/day at lambing, on top of their maintenance requirements. (The maintenance requirement for a 60kg ewe is around 10 MJMe/day.)

Ewes carrying multiple lambs need extra care to ensure they go into lambing in good condition. In the last six weeks before lambing ewes carrying twins require around 60% more energy than single-bearing ewes, and ewes carrying triplets need almost double the amount of energy. Studies have shown that multiple-bearing ewes in good condition are not only able to feed their lambs better, but also have better mothering ability.

Feeding to weaning

Ideally your average pasture cover levels at 1 May will have been 1800 - 2000kg DM/ha. This should set you up for having covers of 600 - 800kg DM/ha six weeks before lambing and 1100 - 1400 kgDM/ha at lambing. Regional grass growth conditions and your grazing management will influence the actual covers you achieve.

Ewes with lambs at foot should be fed at two times their maintenance levels if they have a single lamb, or three times their maintenance levels if they have twins. To meet these requirements you will need covers of around 1400 - 1600kg DM/ha. in a good season, ewes reach peak milk production (two to three litres a day) two to three weeks after lambing. After this, milk production gradually declines and by eight to 10 weeks after lambing it is only around 0.5 litres per day. During this period the amount of pasture lambs consume gradually increases. Lambs should be weaned when they begin to compete with their mothers for feed; this is generally when average pasture heights fall below three centimetres. If feed is not limiting, lambs will typically be weaned at about 10 to 12 weeks of age.

Pasture quality and quantity

While having sufficient pasture is important, the quality also matters. If pasture becomes rank (longer than 10cm), pasture growth and quality will decline (so stock will get lower MJ Me per kg DM feed eaten). To grow good lambs you need high-quality pasture, which is leafy and contains good clover levels; it shouldn't be stalky or contain high levels of dead material. Grazing management can help maintain quality by supporting high clover levels.

Setting up a feed budget will allow you to plan ahead effectively. Once you have visibility of pasture supply versus animal requirements, you can make a plan to fill any deficits, or to control surpluses, so you have the right quantity and quality of pasture available. There are a number of computer programmes that help simplify the process of feed budgeting, or you can construct one manually; either way, if you haven't done one before it is worth getting expert help to set one up.

Using nitrogen

If your feed budget identifies a likely deficit, you need to consider methods of filling it - options include applications of nitrogen (n) and supplementary feeding. Pastures are often n deficient in early spring so it is possible to get good responses to applied n. The right conditions are important, though - soil temperatures need to be above 7 and the soil should not be too wet, to avoid the risk of leaching. Remember pasture needs time, around six to eight weeks, to respond to a n application, so include this time lag in your plan. Apply n at relatively low rates of around 30kg n/ha (65kg urea/ha) at this time of year. lower levels will help decrease the risk of leaching and ensure that the n is used by plants.

In summary, planning ahead, to ensure you have the right quantity of good-quality pasture in late pregnancy and at lambing, is the key to hitting the production targets you have set for ewes and lambs

Article provided by Ballance Agri-Nutrients