Beef and sheep notes May 2008

With the main input costs in the beef sector, namely fertiliser, concentrates and fuel at unprecedented levels, beef farmers have to concentrate on low cost production systems to stay in business.  This means exploiting our cheapest natural resource, grass.  The cost of producing beef from grass is less than 20 percent of the cost of providing the same gain on winter rations.   Aim for 1KG daily liveweight gain over 180-200 grazing days. Our benchmarking results indicate few are achieving this target.

May is normally the most vigorous period of the year for grass growth.  Management decisions made over the next month will have an impact on the performance of stock for the remainder of the grazing season.

With rotational grazing systems aim to have stock entering each field/paddock at a grass height of 15-18 cm (6-7”) and graze down to 5 cm (2”).  

If the production of seed heads does become a problem then top down to a height of 5 cm (2”).  Early topping, that is,  late May to mid June sets the sward up to produce plenty of leaf for the remainder of the season.

Weekly assessment of the grass supply/demand balance is the key to maintaining an adequate quantity of leafy grass ahead of stock at all times. A relatively simple way of assessing grass supply is to use the “Grazing Days Ahead” method. Simply walk across all the fields/paddocks available for grazing with a pen and notebook and estimate how many days grazing, for the group of cattle, is in each division while not taking into account any future growth.

There will be no days in the field just grazed, perhaps one day in a field/paddock grazed a week ago, three days in the next shift and so on.  The sum of the grazing days in each paddock gives you the Grazing Days Ahead. The guideline for May/June is to have15 -20 days grazing ahead of stock.

Each year there are complaints about poor lamb thrive.  For mid-season twin lambs, the expected average growth rate is 1.8 KG per week to 10 weeks of age; 1.5 KGs per week from 11 – 14 weeks and 1 KG per week from week 15 onwards.  This level of growth will give an average weaning weight of 28 – 30 KGs for a flock with a weaning rate of 1.5.

Lamb growth rates can vary greatly depending on the type of pasture being grazed.    Once grass heads out, dry matter digestibility declines from 75+ in mid May to around 60 DMD in mid June.  This is a huge drop in grass quality at a time when March-born lambs are switching feed from milk to grass.

Much of the slow-down in growth rate that we associate with weaning is due to the deterioration in sward quality.

Operating a tight grazing procedure provides adequate nutrition as well as preventing pastures becoming too stemmy later in the season with a resulting fall-off in lamb performance.  In June sward height is increased to at least 8–9 cms.  Grass silage aftermaths introduced mid-season can maintain weight gains as well as helping to reduce worm burden.

Watch out for the first wave of infection from Nematodirus, delayed this year due to the cold spring.  This infection causes severe scouring, affects only lambs and is passed from one year’s lamb crop to the next if they are grazing the same fields as the previous spring.  The disease can therefore be easily prevented by utilising fields on which the previous year’s lamb crop did not graze during the April/May period. Alternatively, prevention of serious infection depends on dosing lambs regularly during the danger period. Wormers have no residual effect against Nematodirus, therefore white or yellow drenches can be used.