Feed intake – how much can they eat
Article printed February 14, 2025. For the latest version, please go to: https://www.feedinglivestock.vic.gov.au/2024/12/30/feed-intake-how-much-can-they-eat/
In choosing the best value feed that will meet the needs of the various classes of stock, you may also need to consider whether the animals can eat enough of the supplement to meet their energy needs. This is particularly relevant when considering cheap but low energy feeds, including those with high fibre content. How much an animal can and will eat will depend on its body weight, requirements to grow, reproduce and lactate and also the quality of the feed. Other factors that may reduce how much they can eat include high water content, some mineral deficiencies, extreme temperatures (very hot or very cold and wet), palatability, trough space, access to feed, feeding time and disease. Generally dry adult sheep will eat 2-3% of their body weight. This proportion increases for growing lambs (approximately 4%) and for lactating ewes (4 to 5.5%) on good quality feed.
Intakes will vary depending on the type of feed as low quality, fibrous feeds will decrease intake. This means that high-fibre diets that have low energy values (like some hays and straws) will not supply enough energy for the animal because they cannot digest enough feed in a day to meet their needs. A measure of fibre that is available with a Feed Test of hay and straw is Neutral Detergent Fibre (NDF). If this measure is known, a simple sum can provide an estimate of how much the animal can eat. The maximum percentage of a sheep’s live weight that can be eaten is 120/NDF%.
Example
A lucerne hay sample has a FeedTest of:
10 MJME/kg DM
15% Crude Protein
50% NDF
NDF of 50% will mean that an estimate of maximum daily intake is 120/50 = 2.4% of bodyweight.
Therefore, the maximum a sheep can eat of this feed per day is 2.4 per cent of its weight.
- A 25 kg lamb could eat about 0.6 kg of this feed per day supplying 6 MJME/kg DM. These animals need to grow and require about 8 MJ ME/day and so could not eat enough to do this, even though the protein level is adequate (Table 3.1) or shown below.
- A 60 kg ewe could eat 1.44 kg/day (at 2.4% of 60 kg bodyweight) which would supply14.4 MJ ME/kg DM. Using the requirements from Table 3.1, this would be enough if she was dry or pregnant (requiring 9 or 14.4 MJME/day respectively) but not once she is lambing (requiring at least 21.5 MJ ME/day). Similarly with the lambs, protein is adequate for all stages.
For a table that helps do the sums on intake, using NDF, click here or go to the bottom of Useful Tables for sheep or beef
