How to locomotion score dairy cows to estimate herd lameness prevalence
By Alea Hoffman, Dale Moore, Jorge Vanegas, John R. Wenz
The first step to remediation of dairy herd lameness is to determine if a problem exists or not. Ideally, all cows should be examined to find those that need attention or treatment. However, to get started with a herd, particularly a large one, getting a representative sample of cows to evaluate might be enough to trigger the next steps – investigation of the likely causes of a herd lameness problem and intervention. This factsheet provides details on locomotion scoring and sampling to estimate a dairy herd’s lameness prevalence.
Assigning a locomotion score
| Score | Means | Gait Description |
|---|---|---|
| 1 | Normal | Cow stands and walks with a level-back posture. Gait is normal. |
| 2 | Slightly abnormal gait | Cow stands with level-back posture but develops an arched-back posture while walking. Her gait remains normal. |
| 3 | Moderately lame | An arched-back posture is evident while standing and walking. Gait is affected and described as short-striding one + limbs. |
| 4 | Lame | An arched-back posture is always evident and gait is best described as one deliberate step at a time. The cow favors one or more limbs/feet. |
| 5 | Severely lame | The cow additionally demonstrates an inability or extreme reluctance to bear weight on one or more of her limbs/feet. |
Arched back: an arched back is one that is convex from the withers to the tail head rather than being flat. If you drew a straight line from the withers to the tail head, would you see the cow’s back arched above the line?
Short-step (or short-stride): is a decrease in the duration and/or distance of the stride of one or more legs. A single stride for one hoof is defined as the distance and time for the same hoof to contact the ground again. Short-stride of a hind limb results in the cow not tracking-up. Tracking-up is the placement of the hind hoof in or adjacent to the footprint of the front hoof on the same side.
Locomotion scoring system based on Sprecher, 1997
How to determine sample size
A sampling strategy has been validated for accuracy in which a calculated sample of cows across the herd, weighted by pen and distributed evenly within the pen, is locomotion scored.
Calculations: (a table for these calculations is included below)
- Determine sample size based on total number of lactating cows in the herd using the table below.
- Weight sample by pen: Some pens have more cows in them than other pens, so more cows in these pens should be locomotion scored. To calculate this for each pen, divide the number of cows in that pen by the total lactating herd size. This gives you the proportion of the herd in each pen.
- For each pen, multiply the proportion in the pen (from step 2) by the calculated sample size (step 1). This gives you the number of cows to score in each pen.
- For each pen, divide the total number of cows in the pen by the number of cows you will score in that pen (from step 3). This gives you the number of cows to count in between the cow to score, we’ll call this number ‘n’. When you go through the pen, you will score every nth cow. For example, if there are 100 cows in the pen and you need to score 20, 100/20=5, so you will score every 5th cow you see. This counting of cows ensures that the sample is distributed evenly across the pen to decrease bias. For example, if more lame cows were closer to the parlor and you only scored the cows on that side of the pen, your prevalence estimate is likely to be biased.
- Locomotion scoring cows: Score every nth cow in the pen until you have scored the number of cows calculated for that pen.
Sample Size Table
| Herd Size | Sample Size | Herd Size | Sample Size | Herd Size | Sample Size | ||
|---|---|---|---|---|---|---|---|
| 20 | 17 | 140 | 57 | 270 | 71 | 900-950 | 87 |
| 30 | 23 | 150 | 59 | 280-290 | 72 | 1000-1100 | 88 |
| 40 | 28 | 160 | 60 | 300 | 73 | 1150-1300 | 89 |
| 50 | 33 | 170 | 62 | 350 | 76 | 1350-1550 | 90 |
| 60 | 37 | 180 | 63 | 400 | 78 | 1600-1900 | 91 |
| 70 | 41 | 190 | 64 | 450 | 79 | 1950-2450 | 92 |
| 80 | 44 | 200 | 65 | 500 | 81 | 2500-3000 | 93 |
| 90 | 47 | 210 | 66 | 550 | 82 | 3500-5500 | 94 |
| 100 | 49 | 220 | 67 | 600 | 83 | 6000-16500 | 95 |
| 110 | 52 | 230 | 68 | 650 | 84 | 17000 & up | 96 |
| 120 | 54 | 240 | 69 | 700-750 | 85 | ||
| 130 | 55 | 250-260 | 70 | 800-850 |
FORM: Calculations for estimation of lactating herd lameness prevalence