RAP Risk factors
The reference animal is defined below. The HLI threshold for this animal is 86.
A table of adjustment factors for the HLI is shown in Table 2. A positive number means that the threshold at which cattle will gain heat is increased by that number (i.e. the HLI threshold goes up), and a negative number means that the threshold will be lower. For example, if 2m2 of shade is available then the threshold for the ‘reference’ animal is 86 + 5 = 91. That means the animal will gain heat when the HLI is 91. Positives are additive but only up to a maximum of 100.
Table 1 - Reference Animal
Parameter | Value |
Cattle type | Bos taurus |
Coat colour | Black |
Health status | Healthy |
Implants | no |
Days on feed | 81 – 120 |
Shade provision | No shade |
Trough water temperature | 20 – 30 degrees |
Manure management class | Class 1 |
Pen aspect | east or south facing |
Table 2 - Adjustments
Parameter | Adjustments |
Factors that remain constant through the life of an animal in the feedlot | |
Breed | Bos taurus genotypes (e.g. Angus, Herefords, Holsteins) 0 Bos indicus cross (25%) (e.g. Australian Brangus) +4 Bos indicus cross (50%) (e.g. Australian Braford) +7 Bos indicus cross (75%) (e.g. Droughtmaster, Santa Gertrudis) +8 Bos indicus genotypes (e.g. Brahman) +10 Wagyu (F1 and Fullblood) +4 European genotypes +3 |
Coat colour | Black 0 Red (red or brindle) +1 White (white grey) +3 |
Days on Feed (Bos Taurus only) | 0 - 80 days +2 81 - 120 days 0 121 - 150 days -3 >151 days -4 |
Days on Feed (Wagyu only) | 0 - 300 days 0 > 300 -2 |
Days on Feed (All other breeds) | 0 - 80 days +2 81 - 120 days 0 121 - 150 days -3 |
Implants | Implanted -1 Non-implanted 0 |
Shade provision | No shade 0 Shade (1.5m2/SCU – 2m2/SCU) +3 Shade (2m2/SCU – 3m2/SCU) +5 Shade (3m2/SCU – 5m2/SCU) +7 Note: Shade area should be calculated at midday |
Pen aspect | East facing slope 0 North facing slope -1 West facing slope -2 South facing slope 0 In a valley - 2 On a plain or on top of a ridge + 2 |
Pen floor condition | Class 1 (Max manure pack depth 50 mm, pen cleaning less than 14 week intervals) 0 Class 2 (Max manure pack depth 100 mm, pen cleaning 14 - 26 week intervals) -4 Class 3 & 4 (Max manure pack depth 200 mm, pen cleaning > 26 week intervals) -8 |
Water trough temperature | Temperature of water in troughs = 15 – 20°C +1 Temperature of water in troughs = 20 – 30°C 0 Temperature of water in troughs = 30 – 35°C -1 Temperature of water in troughs > 35°C -2 |
Factors that can change through the life of an animal in the feedlot | |
Options to reduce risk | Install extra water troughs +1 Implement heat load feeding strategy (if not already feeding. E.g changed ration or reduced feed intake) +2 Strategic clearing of high manure deposition areas +2 Backgrounding +2 Water sprays (if appropriate) + 2 Shade (if not already selected as part of base risk) +5 |
Factors that increase the risk | Wet pens - 8 Ergot and other mycotoxins - 8 Non backgrounding cattle -2 Winter coat - 2 Unacclimatised to local weather conditions (hotter) -3 Sick and recovering (particularly BRD) -5 |
Short term risk factors on hot days | Cattle movement >200 m -3 (for 24 hours) Cattle induction - 3 (for 24 hours) |