Quality silage can lead to big gains
Meal needs reduced by careful planning
Published 14/09/2010 | 05:00
SINCE silage forms the basis of most cattle diets in winter (apart from the final finishing stage) the amount of meal needed to meet target gains determines the quantity to be purchased.
The target gain for weanlings is 0.5 to 0.6kg/day. The higher rate of gain is required where you have a long indoor feeding period. If you can get weanlings out to grass early, a lower gain of about 0.4kg/day can be tolerated since the restricted feeding period is short and the effect of lifetime gain is lessened. A similar picture pertains with store cattle going to grass in spring.
Dry suckler cows should not require any supplementation, except where silage is restricted or cows on poor quality silage are thin at housing. Cows with calves produce 6-10 litres of milk per day while maintaining body condition and so require some meal, except for those on the best quality silage.
Table 1 gives guidelines on meal supplementation rates relative to silage quality for different categories of stock.
Over the past few years most beef cattle that are finished over the winter have been on ad lib concentrate diet for approximately 100 days and consuming 1.0 to 1.25 tonnes of concentrates. Higher concentrate cost will have the greatest impact on the finishing element of the production stage. Nevertheless, in a paper presented to the Beef Conference of the Irish Grassland Association, Dr Siobhán Kavanagh has shown that a high concentrate finishing diet remains broadly competitive with other commonly available diets even at higher concentrate prices (see table 2).
The diets examined were good quality grass silage, maize silage and whole crop silage, all supplemented with 5kg/day of concentrates, grass silage plus 20kg fodder beet supplemented with 2.3kg/day concentrates and the ad lib concentrate diet. At a concentrate price of €200/t the grass silage-based diet remained the most costly. The maize silage diet came out at 91pc of the cost of the grass silage diet followed by the ad lib concentrates and fodder beet at 93pc and whole crop at 96pc the cost of grass silage. It should be noted that the maize, fodder beet and whole crop are assumed to be high quality crops with high energy contents which is crucial for weight gain. For many beef finishers the option will remain between high quality grass silage (if available) and ad lib concentrates.
The weight at which to change from a silage-based diet to ad lib concentrates for final finishing is an important factor in controlling costs. The general recommendation is to grow the animals on forage diets mainly and confine high concentrate feeding to the final 80-90 days for heifers, 90-110 days for steers and up to 200 days for young bulls.