Autumn finishing - to feed at grass or not?
Martina Harrington, Manager of the Future Beef Programme, looks at the key variables farmers have to consider when opting to feed cattle at grass this autumn in order to have animals finished prior to housing.
A difficult year, leading to mixed cattle performance, reduced grass growth rates and in some cases a limited supply of silage, has some farmers questioning: ‘Should I feed concentrates at grass to get animals sold before the winter or will concentrate supplementation help extend the time at pasture this autumn before housing for the winter?’
When compared with spring grass, autumn grass generally has a lower feed value. Additionally, weather and grazing conditions in autumn may be less than optimum. Geographical factors also need consideration; grazing and ground conditions in drier regions may be much more conducive to weight gain than those achieved on more challenging soil types.
While every effort should be made to maximise the proportion of autumn grazed grass in the animal’s diet, the strategic use of expensive concentrate supplementation at pasture to enhance the energy density of the diet might be considered, especially if winter silage stocks are low.
The role of concentrate supplementation
Supplementation with concentrates aims to maintain autumn animal live weight gain. In the case of heavier animals, it helps to achieve an acceptable carcass fat score, giving farmers then the option to market animals off pasture.
One important factor to consider when feeding cattle is the substitution rate, which is the reduction in grass intake when concentrates are given. Research at Teagasc Grange found that when finishing cattle on autumn pasture with concentrates, the substitution rates varied widely, depending on the availability of grass.
If grass was limited, the substitution rate was low, meaning the cattle still ate a lot of grass and concentrates are a clear addition to the animal’s intake. However, if there was plenty of grass, concentrates reduced grass intake (concentrates simply substituted grass), but they usually increased the overall intake of dry matter and energy.
Given the above, if pasture supply is low or of poorer quality, a worthwhile growth response to concentrate may be expected. However, if pasture quality is good and supply is not limited then the economic response to concentrates might be questionable.
The response to meal feeding
Two scenarios are outlined below. The first scenario deals with animals that are reaching a finishing weight / fat cover and are nearing slaughter. These animals are within 60kg of their target finishing weight. The second is what to do with cattle that won’t finish until next spring.
Studies at Teagasc Grange have shown that with adequate grass in autumn, feeding 0.5-0.75kg of concentrate per 100kg of live weight resulted in carcass growth responses between 30 and 110 grams per kilogram of concentrate. Feeding a moderate level of concentrate (0.5 kg/100 kg live weight) is likely to give good growth results.
Table 1: Effect of feeding strategy on finishing performance
| Suckler steers (95 days) | Suckler steers (75 days) | Beef x Dairy steers (AAX) (112 days) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Finishing strategy | Grass only | Grass + 5kg of concentrates | Difference | Grass only | Grass + 5kg of concentrates | Difference | Grass only | Grass + 1.5kg of concentrates | Grass + 3kg of concentrates | Difference 0kg vs. 1.5kg | Difference 1.5kg vs. 3kg |
| Daily live weight gain (kg) | 0.34 | 1.04 | 0.7 | 0.81 | 1.14 | 0.33 | 0.80 | 0.88 | 0.91 | 0.08 | 0.03 |
| Slaughter weight (kg) | 547 | 596 | 49 | 604 | 667 | 63 | 459 | 469 | 471 | 10 | 2 |
| Carcass weight (kg) | 291 | 323 | 32 | 334 | 379 | 45 | 226 | 233 | 236 | 7 | 3 |
| Kill-out proportion (g/kg) | 532 | 541 | 9 | 554 | 568 | 14 | 488 | 498 | 500 | 10 | 2 |
| Carcass conformation | 6.3 | 7.6 | 1.3 | 7.5 | 8.8 | 1.3 | 5.2 | 5.4 | 5.2 | 0.2 | 0 |
| Carcass fat score | 6.2 | 7.4 | 1.2 | 7.5 | 8.3 | 0.8 | 5.1 | 5.6 | 5.8 | 0.5 | 0.2 |
For instance, table 1 shows that for suckler steers, feeding 5kg of concentrate daily, over 95 days, resulted in a significant increase in daily live weight gain (from 0.34kg to 1.04kg) and carcass weight (from 291kg to 323kg). That’s an extra 32kg of carcass for 476kg of meal. When meal is costed at €320/t and a kilogram of beef carcass at €5.15, that’s an extra €165 per animal at a cost of €152, in simple sums.
In the first example, concentrate feeding increased kill-out percentage by almost 1 percentage unit and improved both conformation (1.3 units: from O+ to R-) and fat score (1.2 units: 2+ to 3-) The results are similar for the second suckler trial.
However, in the beef x dairy steer category, there was only a small carcass weight response to the initial 1.5kg of concentrates, but not to the next increment. So feeding 168kg of concentrates/head resulted in an additional 7kg of carcass (1.5kg vs none) and feeding an additional 168kg concentrates (1.5 kg vs. 3kg) only resulted in an additional 3kg of carcass. In this case, both pasture quality (DMD 720g/kg) and quantity (pre-grazing herbage mass ~1800 kg DM/ha) were adequate to meet the animals’ needs.
However, for forward stores that won’t finish until next February, it may be better not to supplement them as some data shows that when comparing autumn supplemented and unsupplemented animals that go indoors for finishing, any advantage attained by the supplemented animals is subsequently lost or much reduced indoors and both groups end up similarly with compensatory growth
Health warning – your health is your wealth
Feeding a large number of cattle at grass does carry health and safety risks. A lot of large cattle rushing into feed can knock you over and walk on you, thus causing a risk of falls or mauling. It is best practice to try and avoid being in with the cattle when feeding; feed under the wire, have the trough fenced off that you can fill meal and then let in cattle, or have automatic feeders etc.
Also read: Sustainable practices on Kay O'Sullivan's beef farm in Co. Cork
Also read: Future Beef Farmer, Shane Keaveney on his suckler to beef system