AE ratings & calculating forage demand
Meat & Livestock Australia April 15, 2024
How do I work out what AE rating my animals are?
Firstly, a reminder that we use AE as the unit of measure so that we can compare different classes of animals with each other and the consequent effects on how much they eat.
Before we look at the reference tables, it may be useful to know that lighter classes of stock such as weaners, always convert to less AEs than the number of weaners. Heavier classes of stock such as bulls always convert to more AEs than the number of bulls.
AE ratings for different classes of animal
These tables provide annualised estimates of AE ratings for various classes of animals in three productivity zones:
- Low productivity: steer weight gain of <110kg/year.
- Moderate productivity: steer weight gain of 110-150kg/year.
- High productivity: steer weight gain of >150kg/year.
Note: the productivity zone applies to the whole property within a region.
All AE ratings represent the energy demand of animals relative to the standard animal (450kg bos taurus steer with zero liveweight gain).
Annual AE Ratings
Productivity
Low
Moderate
High
Females <1#
0.57
0.68
0.77
Females 1-2
0.72
0.91
1.10*
Females 2-3
0.96*
1.12*
1.74*
Females 3-4
1.18*
1.49*
1.61*
Females 4+
1.09*
1.29*
1.53*
Steers <1#
0.60
0.72
0.80
Steers 1-2
0.78
1.03
1.31
Steers 2-3
1.02
1.27
1.60
Steers 3-4
1.15
1.39
1.78
Grown Bulls
1.48
1.73
1.78
Intake/AE
8.5
8.0
7.5
#Is from weaning to 12 months of age
*includes pregnancy, lactation and calf to weaning and accounts for reproductive rate (i.e. is average of all females in age group)
Category
Animal equivalent rating
Horses
1.20
Kangaroos
0.07
Downloadable PDFs for AE ratings and daily intake:
Can I just estimate my stock numbers if I don’t know them?
In case you aren’t convinced that having an accurate handle on your cattle numbers and their AE ratings, is necessary for you to complete an accurate forage budget, without accurate herd numbers (+/- 1-2%):
- You do not know your grazing load (average annual AE carried).
- You don’t know your herd productivity in terms of;
- kg beef produced, in total and per AE
- reproductive rate
- mortality rate.
- You don’t know your herd value.
- You don’t know your business income (herd inventory change affects income).
How do I calculate forage demand (kg/ha)?
Information needed:
- paddock area (ha)
- number of days you are completing the forage budget for (Start date – end date)
- total AE (Animal Equivalents) in the paddock or on the property
- dry matter intake (kg/AE/day).
Demand = (Dry matter intake x AE x number of days) / paddock area
EXAMPLE: Jack is wanting to complete a forage budget for one of his back paddocks (GULLY PADDOCK). He currently has 300 steers (aged between 1-2) with an average weight of 350kg. He needs to calculate the demand (kg/ha) of these animals between 1 April 2024 and 1 November 2024. Jack lives in a low productivity zone.
NOTE: The demand of these animals will change if Jack provides them with supplementation, particularly a protein supplement.