Importance of Pasture Quality
Top stock growth rates are a fast-track to higher sheep farm profits.
Energy requirements, feed requirements and dry matter, profitability of 30 kilogram liveweight lambs growing at different rates after weaning.
| Post weaning liveweight gain (g/day) | ||||||
| 50 | 100 | 150 | 200 | 250 | 300 | |
| Daily energy requirement (MJ ME/day) | 11 | 13 | 15 | 17 | 19 | 21 |
| Daily dry matter requirement (kg DM/day) | 1.0 | 1.2 | 1.4 | 1.5 | 1.7 | 1.9 |
| Time for 1 kg carcass weight gain (days) | 45 | 23 | 15 | 11 | 9 | 8 |
| Total energy requirement (MJ ME) | 495 | 299 | 225 | 187 | 171 | 168 |
| Total dry matter requirement (kg DM) | 45 | 27 | 20 | 17 | 16 | 15 |
| Return on dry matter (c/kg DM) | 7 | 12 | 16 | 18 | 19 | 21 |
The figures spell it out - lambs that are growing faster are far more efficient converters of pasture to meat They reach target liveweights more quickly, eat less feed in doing so and provide a much better return on the valuable dry matter you invest in them.
Increasing lamb growth rate from 50 g/day to 150 g/day more than doubles your money - from 7 to 16 cents return on every kilogram of dry matter your lambs consume. Grow your lambs at the magic 300 g/day and your dry matter returns a whopping 21 c/kg - three times the return on your grass!
Give Them Quantity and Quality
Offer them plenty - lambs need plenty of feed in front of them for top liveweight gains - pastures should never be below 1500 - 2000 kg DM/ha.
Give them your best - quality feed is all important to make sure that lamb intakes provide the energy needed for fast growth. Pastures should comprise green leaf and a high legume content (e.g. 20 - 30 % clover), especially just after weaning.
Just how important is Summer/Autumn feed quality? - This is the focus of the West Waikato Feed Quality Study Group who have been measuring the quality of their pastures and other summer feeds. Typically summer pastures fed to lambs have had a quality around 9.5 ME/kg DM1 ranging from about 8.5 to 10.2 (the latter was a young leafy clover/ryegrass pasture). Chicory and Pasja crops measured around 13. The effect feed value, ME/kgDM, has on lamb growth rates is illustrated in table 2.
Feed value, maximum intake; as DM, as ME, and maximum weight gain (LWG) as grams per day for a 30kg lamb.
| ME/kgDM | Max DM | MaxME | LWG |
| 7 | 0.5 | 3.6 | -90 |
| 8 | 0.8 | 6.0 | -40 |
| 9 | 1.0 | 9.2 | 30 |
| 10 | 1.3 | 12.9 | 110 |
| 11 | 1.5 | 16.8 | 200 |
| 12 | 1.8 | 21.1 | 290 |
Top fuel - top performance. So a 30 kg lamb on feed with an ME/kgDM of 12 has a maximum intake of 1.8kg DM or 21.1 megajoules of ME and so it can only grow at 290 grams of liveweight per day.
Poor fuel - poor performance. The contrast is again a 30kg lamb on pasture with an ME/kgDM of 10. It can only achieve LWG of 110 g/day.