Calculating Daily Requirement
24 September 2018
Calculating the daily requirement of the crop is a simple task, which is extremely beneficial to making the crop last longer, while balancing the nutritional requirements of the livestock. If livestock are given too large an area, they are prone to eating all leaf material (high in protein) and then going back to the bulb (high in energy). This also results in wastage of the crop from trampling.
The first step is to gather material from within a 1m square quadrat on a representative area of the field. This should then be weighed, with the weight being multiplied by 10,000 to give you the fresh weight/ha. This can then be multiplied by the estimated dry matter of the crop (stubble turnips 9%) divide by 100 and you have your dry matter/ha.
Using the dry matter (DM) yield a daily allocation can be calculated depending on the stock class grazing the crop e.g. stubble turnips. An example is shown below for a 70kg ewe.
| Example: 70kg ewe | ||
| A | Total Estimated Intake (using 2% of liveweight) | 1.40kg DM/day |
| B | Stubble turnips Inclusion of The Diet (allowing 30% fibrous forage) | 70% |
| C | Daily Requirement of stubble turnips (AxB) | 0.98kg DM |
| D | Number of Animals Grazed | 500 |
| E | Daily Requirement of stubble turnips (CxD) | 490kg DM |
| F | Estimated Crop Yield (DM/m2) (dry matter/ha – 4t DM/ha @ 70% utilisation – (4kg/m2 x 0.7) | 2.8 kg/DM/m2 |
| G | Total Grazing Area Required/Day (E/F) | 175 m2 |
| H | Length of Electric Fence (Feed Face) | 150m |
| I | Width of Fence Moved Per Day (G/H) | 1.2m/day |
Kirsten Williams, kirsten.williams@sac.co.uk
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