So you want to buy a Goat and it has these weird letters and numbers after its name. What's that about and why should you care?
UNDERSTANDING DAIRY GOAT LINEAR APPRAISAL
Dairy goat Linear Appraisal is one method used by the American Dairy Goat Association to evaluate the quality of a dairy goat. All dairy goats, irrespective of breed, are judged against the same scorecard and in the same way.
The linear trait information can be extremely useful when trying to make breeding decisions since it provides specific scores for heritable traits.
According to the ADGA handbook, “The linear appraisal system evaluates individual type traits that effect structural and functional durability to take full advantage of the potential for genetic improvement through selection
Each goat is assessed in four separate parts by an appraiser sent by the ADGA. The four parts are as follows
1) PART 1 – LINEAR TRAITS
The numerical description of 14 linear traits on a 50 point scale that represents the biological range for that particular trait. It is this linear trait data, plus the animal’s final score (item 4) that are used by the ADGA and USDA to develop sire summaries. Just seeing what these different traits were, and learning about why they are important was extremely beneficial for me.
LA FORM – STATURE
The appraiser’s evaluation of stature is based on the distance from level ground to the top of the withers. Goats 26” or less are considered extremely short and assigned five points or less. Goats that are 30” tall are considered intermediate in stature and assigned 25 points, while goats at least 34” tall are considered extremely tall and assigned 45 or more points. For each 1” difference in height, plus or minus, the point assignment changes by five. Stature in Miniature breeds is recorded in inches to the nearest 1⁄4 inch as data is collected to determine the biological range. Height for Nigerian Dwarf buck should be no more than 23.5 inches and 22.5 inches for a Nigerian Doe.
LA FORM – STRENGTH
The width and depth of the chest, the width of the muzzle, and the substance of bone in the goat’s front end are used to determine the strength of the goat. The range for this trait is from extremely narrow and frail to extremely wide and strong. Width and strength is associated with the likelihood the goat can sustain high production and good general health. Strength is measured from weakness (less than 20 points) to strength (more than 30 points). The intermediate range is from 20 to 30 points.
LA FORM – DAIRYNESS
When evaluating Dairyness, the appraiser considers length, cleanness and flatness of bone, length and leanness of neck, definition and sharpness of withers, degree of fleshing, femininity and refinement, and fineness and texture of skin. Dairyness is measured from coarseness (which is assigned 10 points or less) to extreme sharpness (which is assigned 40 or more points).
LA STRUCTURE – RUMP ANGLE
The angle of the rump or pelvis from hips to pins has a direct bearing on the reproductive performance of a goat because it influences the ease of kidding and drainage of the reproductive tract. The angle of the rump is also related to the length of udder from fore to rear, strength of fore udder attachment, and udder depth. Observing the goat on the move from the side, the appraiser evaluates the angle of the rump from the hips to the pins. Rump angle is measured from steepness, which is assigned 20 or less points, to levelness, which is assigned 30 or more points. Rumps intermediate in slope (30° to 20°) are assigned 20 to 30 points. Each difference of 5° in the rump angle, plus or minus, results in a difference in the score of 5 points. A rump angle of 50° or more is assigned 1 point.
LA STRUCTURE – RUMP WIDTH
The width of the rump is important for three reasons. The width of the rump relates to kidding ease; the wider the rump or pelvis, the easier the delivery of kids. The width of the rump also is an indicator of general body width throughout, as well as the potential for udder width. Rump width is determined as the width between the thurls; that is, the width of the pelvic girdle. An extremely narrow rump (5” or less) is assigned 5 points or less, a rump of intermediate width (7”) is assigned 25 points, and an extremely wide rump (9” or more) is assigned 45 or more points. Rump Width in Miniature breeds is recorded in inches to the nearest 1⁄4 inch as data is collected to determine the biological range.
LA STRUCTURE – REAR LEGS, SIDE VIEW
This trait relates to the durability of the legs and feet, as reflected by the degree of angle of the hock. By looking at the goat from the side, the appraiser can evaluate the degree of angle to the rear leg. The less angle or postier the leg, the lower the score. An intermediate angle in the hock relates to the midpoint of the range. Legs that tend toward straightness (or postiness) are assigned 20 or less points. Legs that tend toward greater angulation are assigned 30 or more points.
LA MAMMARY – FORE UDDER ATTACHMENT
In evaluating the fore udder attachment, the appraiser looks at the strength of the attachment of the lateral ligaments as they extend forward and laterally to the body wall. The scale ranges from an extremely loose attachment (5 points or less) to an extremely snug and strong attachment. Fore udders with lateral ligaments that are intermediate in strength and tightness are assigned 25 points.
LA MAMMARY – REAR UDDER HEIGHT
The height of the rear udder attachment is an indication of the goat’s potential capacity for milk, in that it affects udder capacity, and of the udder’s ability to hold its shape and position through repeated lactations. Rear udder height is scored in proportion to the goat. An extremely low attachment is assigned 5 or less points; udder attachments of intermediate heights are assigned 25 points; while an extremely high attachment is assigned 45 or more points. Differences in hair and issue texture between the rear udder and escutcheon are used as aids in determining the point of attachment. This trait is not recorded in bucks.
LA MAMMARY – REAR UDDER ARCH
The evaluation of rear udder arch considers both the width and the shape of the attachment of the rear udder. The rear udder arch is an indication of the goat’s potential capacity for milk, in that the width and shape of the rear udder attachment affects udder capacity, and the udder’s ability to hold its shape and position through repeated lactations. An extremely narrow and pointed rear udder arch is assigned 5 or less points, a rear udder intermediate in width and arch is assigned 25 points, and a rear udder that is extremely wide and arched assigned 45 or more points. Rear udder arch is evaluated at the same spot as rear udder height. Differences in hair and skin texture between the udder and the escutcheon are used to determine the point of attachment.
LA MAMMARY – MEDIAL SUSPENSORY LIGAMENT
The medial suspensory ligament is the primary support for the udder. A strong medial suspensory ligament affects the goat’s production potential by keeping the teats in place and the udder elevated, reducing the potential for injury. An udder with a weak medial suspensory ligament, resulting in a negative cleft or bulge in the floor of the udder, is assigned 5 or less points. An udder with clearly define halving and support (1” cleft) is assigned 25 points, and an udder with an extreme cleft (3” or more) is assigned 45 or more points. The assignment of an udder support score is based on the appraiser’s evaluation of the amount of cleft in the floor of the udder attributable to the medial suspensory ligament. A difference of 1” in the amount of cleft, plus or minus, results in a difference of 10 points.
LA MAMMARY – UDDER DEPTH
The depth of the udder is measure relative to the hocks. While some degree of udder depth is necessary for capacity, an udder that is extremely deep is more susceptible to injury and mastitis infection. Udder depth is evaluated as the vertical distance between the floor of the udder and the point of the hock, when the rear leg is set in a normal position under the animal. A deep udder that is at least 2” below the hocks is assigned 5 or less points, an udder that is intermediate in depth (2” above the hocks) is assigned 25 points, and a shallow udder that is extremely high above the hocks (6” or more) is assigned 45 or more points. An udder that is 3” or more below the hock is assigned 1 point. Proportional adjustment is made for miniature breeds.
LA MAMMARY – TEAT PLACEMENT, REAR VIEW
Teat placement, as viewed from the rear, is related to both ease of milking and susceptibility to injury. Teat placement is measured from being on the outside third of the udder half (less than 25 points) to being less than two-thirds of the way out (more than 25 points). Teats that are located one-third of the way out on the udder half are assigned 45 points; teats that are less than one-third of the way out are assigned more than 45 points. Position is determined by the center of the teat at the point where the teat attaches to the udder.
LA MAMMARY – TEAT DIAMETER
Teat diameter is evaluated as the diameter of the teat at its base where it meets the udder, as viewed from the rear. Both delineation of the teat from the udder and ease of milking are reflected in the evaluation of teat diameter. A very narrow teat, 1⁄2” or less in diameter, is assigned 5 or less points; a teat that is intermediate in diameter (1-1/2”) is assigned 25 points; and a teat that is very wider (2-1/2”) or more in diameter, is assigned 45 or more points. A difference of 1⁄2” in teat diameter, plus or minus, results in a difference of 10 points.
LA MAMMARY – REAR UDDER, SIDE VIEW
Rear udder, side view, is evaluated as the shape of the rear udder as it extends behind the rear leg when a goat is standing with her rear legs squarely beneath her. The shape of the rear udder from the teats to the rear udder attachment is an indication of the capacity of the rear udder for milk. Extremely flat rear udders, with little capacity, are assigned 5 or less points; rear udders with intermediate fullness are assigned 25 points; and rear udders that are extremely bulgy or protruding are assigned 45 or more points.
PART 2 – STRUCTURAL CATEGORIES
The appraiser evaluates each animal in 8 structural areas (head, shoulder assembly, front legs, rear legs, feet, back, rump, and udder texture) and assigns a score of poor (P), fair (F), Acceptable (A), Good Plus (+), Very Good (V), or Excellent (E).
Excellent E = 90 and above (at least 90% of ideal)
Very Good V = 85 – 89 (85% to 89% of ideal)
Good Plus + = 80 – 84 (80% to 84% of ideal)
Acceptable A = 70 – 79 (70% to 79% of ideal)
Fair F = 60 – 69 (60% to 69% of ideal)
Poor P = below 60 (less than 60% of ideal)
PART 3 – MAJOR CATEGORIES
The appraiser evaluates each animal in 4 major categories (3 for a buck) of general appearance, dairy character, body capacity, and mammary and assigns a score using the same ratings as those used for the structural categories (P, F, A, +, V, and E).
PART 4 – FINAL SCORE
The final score for an animal becomes part of the computer record used to develop sire summary information, while the evaluation of the major categories is used by the appraiser in arriving at a final score and to provide the herd owner with additional information about each animal.
The four major categories are assigned a letter designation rating, rather than a numerical score. The final score represents how close the overall animal comes to the ideal. Each Major Category contributes to the Final Score based on the following percentages:
Mature Does (any doe which has ever freshened)
General Appearance 35%
Dairy Strength 20%
Body Capacity 10%
Bucks and All Young Stock
General Appearance 55%
Dairy Strength 30%
Body Capacity 15%
Final Linear Assessment Record (example)
IDENTIFYING LA SCORES
After participating in linear appraisal, the scores for each goat can be found at the ADGA site. But scores from the last two parts (magor categories and final score – the last five entries on the form above) can often be found in pedigree information posted by owners for their animals on-line. These usually look something like this: LA VEEV 88 (this translates into Linear Appraisal results of Very good for general appearance, Excellent for dairy character, Excellent for body capacity, and Very good for mammary, with a final score of 88) .
These scores can be very helpful when making decisions about purchases or selection of herdsires because you can get a relatively quick idea about the quality of an animal in specific areas.
Although I often see linear appraisal information specified like that above, the age of the animal when appraised is also supposed to be identified. That’s because young does change dramatically as they mature, and in the example above, a young doe would likely only score a V (at best) in the mammary category. As she matures and her udder develops, that V in mammary could easily change to an E. So, the proper way to specify the major category and final score is: LA 03-03 88 VEEV (this adds the information that the doe was 3 years and 3 months old at the time of this appraisal).
USING LA INFORMATION
When looking at linear appraisal numbers, keep in mind that for the Nigerian Dwarf goat breed, the highest that a goat has ever scored is a 93! Goats that score in the high 80’s or low 90’s are doing very well.
The information recorded during linear appraisal can be extremely useful for making decisions on breeding or buying goats. There are many ways the information can be utilized, for example:
If you owned a doe that’s teat diameter was too small (in your opinion), then when breeding that doe you could look at the linear trait teat diameter scores for the potential sire’s dam and sisters to determine where they scored in teat diameter. By choosing a sire descended from does with better teat diameter, the chances are very good that the teat diameter of any doe kids will be improved.
Or, if just generally looking to improve an area of a herd such as mammary, choosing a sire with dam’s and grand-dam’s that scored an E in the mammary category would likely accomplish that goal.
Of course, linear appraisal doesn’t show anything about milk production or show wins, so depending upon goals, it’s important to investigate further – but it is a valuable tool and provides lots of detail for the herd owner.