Linear Measurement
Here we explain the Linear Measurement system developed by Gearld Fry and used extensively by Bakewell for evaluating cattle. Bakewell offers hands-on workshops in the use of this system.
Linear Measurement is a method of assessing live animals with an objective standard rather than a simple visual appraisal. This concept has been around for centuries (indicated on cave paintings from the 1200s in France, for example), but it has rarely been used in the livestock industry. Gearld Fry became a careful student of the work of Jan Bonsma, an animal scientist and author of the book Man Must Measure. Bonsma created the Bonsmara breed in South Africa by extensive use of measurements of many parts of the animal, including hair diameter, hide thickness, and so forth. (This book is available from www.bovineengineering.com.)
Gearld Fry studied Bonsma's concepts and proceeded to develop a system of measuring as well as tools for that purpose. These measurements, combined with a linear measurement spreadsheet Gearld has developed, allow us to sort and rank animals on qualities such as reproductive viability, volume of retail product, early maturity, and economically superior performance on grass.
We attended a recent seminar at Teddy Gentry's ranch in Alabama. Teddy Gentry harvests data on all of his animals, and he was able to compare the retail value of two different steers. These steers were exactly the same live weight and had comparable ultrasound statistics; they both were tender and had a similar amount of intramuscular fat. After the cattle were slaughtered, the resulting meat was weighed to compare the value of resulting retail cuts. One animal produced $400 more retail value than the other. The reason for the difference in value became clear once Linear Measurement data on the two animals were compared: the animal producing the greater retail value had a heart girth that was four inches larger than its top line; the other steer showed a one inch deficit for the same comparison.
LINEAR MEASUREMENT, GUIDELINES & CORRELATIONS: FEMALE
TOP LINE
Four measurements are taken along the top of the animal.
-
Top line is the total length of the animal from the front of the poll to the back of the rump. (See Fig. 1.)
-
Rump length is measured from the back of the rump to the hook bones.
-
Two-thirds body length is the distance from the middle dip in vertebrae between the shoulder blades to the back of the rump.
-
Neck length is the measurement from that same dip to the poll.
If the back is too long in relationship to the neck, the animal is out of balance. Long backs tend to be weak and will sway. Most long backs have too small a loin muscle and generally result in an irregular shaped loin muscle. The animal will break or dip behind the top of shoulder in the area of the loin muscle. These breaks or dips are a structural defect and are not acceptable in a quality herd.
HEART GIRTH
Heart girth is defined as the total distance around the animal (circumference) measured directly behind the front leg. The heart girth should be equal to or larger than the top line measurement at 12 months of age. Sufficient heart girth is needed to allow for proper size of the vital organs (heart, lungs, glands, and rumen). The closer the heart girth is to the top line measurement, the more efficient, adaptable and vigorous the animal will be. Heart girth that is larger than top line measurement is better yet. Indeed, for each additional inch of heart girth greater than the top line, there will be an additional 37 pounds of meat in the high-value part of the animal, the loin and rump.
Small heart girth is not acceptable. Insufficient heart girth is an indicator of structural defects, which allow a hooked toe or the front feet to toe out. An animal with small heart girth is more susceptible to stress, requires higher maintenance inputs, and does not perform well on grass. Reproductive efficiency suffers as well.
Goal: Heart girth should equal or be greater than the top line measurement.
NECK LENGTH
Neck length should be equal to half the two-thirds body length measurement. A well-balanced cow will have a neck half the length of her body; the ideal range is +.5 or -.5 inches. If the neck is too long, the cow will tend to over-produce milk (what we call "very dairy"). It will be a high maintenance animal, a slower breeder, and will be stressed easily. Her daughters will also have long necks. If the neck is too short, the cow will be wider in the shoulders (coarse), and her milk production will suffer. There will also be a lack of reproductive efficiency.
Goal: Neck length should equal one half of the two-thirds body length measurement for correct balance. Plus or minus one half inch is tolerable.
SHOULDER WIDTH
Shoulder width should be the same as rump length (not to be confused with rump width, as shown in Fig. 2). Subtract the rump length from the shoulder width. The ideal range of the difference between these two measurements is 0 or +.5 or -.5 inches. Shoulders that are too wide in a female will cause a lack of milk production. If the shoulder of the female is much narrower than the rump length, this structural defect results in reproductive problems and is also is an indication of a high maintenance animal. In the cow, the shoulders should balance the rump length.
Goal: Shoulder width should equal rump length. A value of 0 is ideal but a difference of ½ inch plus or minus is tolerable.
RUMP LENGTH PERCENTAGE
To derive the rump length percentage, divide the rump length by the two-thirds body length. In females, the rump length percentage should not exceed 40% of the two-thirds body length; 38% to 40% is the ideal range. Either side of this is in the extreme. The rump length percentage sets the standard for efficient reproduction.
Goal: Rump length percentage should equal 40%; 38% to 40% is the optimal range for balance and reproductive efficiency ("femininity").
FLANK GIRTH
Flank girth, or circumference, is measured in front of the udder and in front of the hook bones. When flank girth exceeds heart girth, this is an indication of fertility and suitability for reproduction. The greater the flank circumference is than the heart girth, the higher the fertility.
Use these guidelines:
-
The flank area should be 2 to 10 inches larger than heart girth at 12 months.
-
Larger is better.
-
"High flanked" (meaning deficient in flank girth) cows have a tendency to be a little more flighty.
- High flanked cows have less meat on the rump.
- High flanked cows have a tendency to be higher maintenance animals.
- High flanked animals will take longer to finish on grass.
Goal: Subtract the hearth girth measurement from the flank measurement. Optimally we would like to see two to ten inches more flank girth than heart girth in a female.
RUMP WIDTH PERCENTAGE
Rump width percentage is obtained by dividing the rump width by the hip (rump) height. This proportion is an important indicator of femininity. A rump width percentage of 40% or more indicates the cattle will have the ability of self-fleshing, will be "easy keepers," and will be reproductively efficient. The greater this percentage is, the greater the volume of meat on the rump. The wider and deeper the rump and flank, the higher the maternal characteristics. Cows with wide rumps typically have sons and daughters with wide rumps.
Goal: Rump width percentage (rump width divided into rump height) should be at least 40%. A higher percentage is better for reproductive efficiency and volume of retail product.
ADJUSTED RUMP WIDTH
The adjusted rump width is the rump width minus rump length. The rump width should be 2.5 inches wider than its length. The wider the rump is in comparison to the rump length, the better. An adjusted rump width of 2.5 or larger is an indicator of high fertility. The wide-rumped cow has sons with short necks. The wide-rumped cow has daughters with wide rumps. The wide-rumped cow has more meat in the rump area and produces sons and daughters with more meat. The progeny will mature earlier and finish by 16 to 18 months of age on grass.
Goal: Adjusted rump width (rump width minus rump length) should be 2.5 inches or greater. Wider is better.
RUMP HEIGHT
Moderate rump height correlates highly with ability to gain weight rapidly on grass and a forage only diet. Tall animals tend to be out of balance, are slow to come into puberty, and are thus lower in fertility and reproductive efficiency. They are late maturing, have smaller loins and need high energy inputs. For overall performance and finishing on grass, a frame score of 3.5 to 4.5 (that is, 46" to 48") works best.
Goal: Rump height should be moderate, between 46" and 48".
THURL
Thurl should be 13% of the rump height or greater. Greater is better if the slope of the rump is of the proper angle. (See Fig. 1.) Thurl should be 13% of hip height or greater, which indicates pelvic depth and structural soundness of hind legs. If the thurl is properly in place, the animal will track (back foot in front track). The measurements are taken from ground to stifle joint and from the stifle joint to top of the back. Properly structured thurl makes for ease of calving.
Goal: The thurl should be 13% of the rump height or greater.
UDDER
The udder should be small and tucked neatly between the back legs with
four equally placed nipples 3-4 inches long. The udder should attach high
up behind the back legs for longevity and soundness. The udder should blend into the lower part of the belly very smoothly with no V or crevice between the udder and stomach. The udder should not be tilted up in front (tilted udders have less milk). Tilted udders are a structural defect resulting from the sire and his scrotal makeup. The udder has a direct influence on the scrotal make up and navel area of the cow's sons.
Goal: The udder should be small and well positioned.
|
