Farm Ireland

Tuesday 24 October 2017

Relative costs of feedstuffs

Studies show there are cost-effective supplements to help you finish off cattle in winter monthsBalancing the concentrate needs

Mark McGee

This is the time of year when grass supply rarely meets the increasing demand of cattle destined to be finished over the coming weeks and months. The challenge of meeting the nutritional needs of your cattle is compounded by the fact that the feeding value of grass is decreasing with each passing week.

Research at Grange has shown that even on well- managed pasture with daily dry matter allowances of 20g/kg liveweight of high digestibility grass, liveweight gain of finishing cattle in autumn was only 0.8kg/day. Contrast this with the much higher gains, often more than 1kg/day, obtained earlier in the season. In practice, animal performance is often substantially less than this.

Consequently, options for finishing of cattle in autumn generally involve concentrate supplementation at pasture or finishing indoors.

As grazed grass is considerably cheaper than either grass silage or concentrates, early finishing of cattle at pasture in autumn, before housing becomes necessary, is less costly. In situations where complete finishing at pasture is not possible, short-term supplementation at pasture is often worthwhile as it still reduces the requirement of more costly conserved forage.

For example, the build-up or adaptation period to concentrates may be implemented at pasture prior to indoor finishing. Diet aside, there are also the obvious substantial costs associated with feeding cattle indoors when compared with grazing.

Concentrate feeding level at pasture

Animal response to concentrate supplementation while grazing will depend on the availability and quality of pasture and level of supplemented concentrate.

One of the most important factors to consider is the substitution rate of concentrates for overall grass intake.

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Research at Grange shows substitution rates for finishing cattle grazing autumn pasture supplemented with concentrates ranging from 0 to 0.81, with marginal values at higher levels of supplementation in excess of 1.0 in some studies.

In other words, where grass supply was restricted, substitution rates were low, but where grass supply was adequate, increasing the level of concentrates reduced grass intake but usually also increased total dry matter and energy intake.

Consequently, carcass growth response to concentrate supplementation at pasture in autumn is higher where grass supply is low and where grass quality is poorer and it declines as concentrate supplementation levels increase.

Studies at Grange have shown that at adequate (20g/kg liveweight) grass allowances in autumn, feeding 0.50-0.75kg of concentrate per 100kg liveweight resulted in growth responses of 30-110g carcass per kilogramme of concentrate.

In practice, feeding this moderate level of concentrates will likely result in carcass growth responses at the upper end of this range.

Concentrate type

In autumn, the diet of grazing cattle is generally unbalanced, in terms of energy and protein, because there is usually excess degradable protein in autumn grass.

Our research has shown dietary energy rather than protein is the limiting factor and supplementation with concentrate energy sources is required.

Three studies at Grange showed that animal performance was similar for starch-based (barley) or fibre-based (pulp) concentrates as supplements to autumn grass. These findings show that beef producers have the opportunity to source cost-effective concentrate supplements.

Mark McGee is a researcher at Teagasc's research centre at Grange, Dunsany, Co Meath

Indo Farming