Superior Genetics

What is SG (Superior Genetics)?

SG is an ADGA awards program that identifies goats with high genetic potential for good milk production and/or conformation (linear appraisal scores). Twice a year (August and November), ADGA updates the PTIs of all purebred or grade goats (no experimentals). Milk test data is added for both updates, but linear appraisal data is only added in the November update. The top 15% PTI scores of each gender of each breed receive the SG designation. That title stays with them permanently, even if they fall out of the top 15% later in life.

What is PTI (Production/Type Index)?

PTI is a ranking that combines milk test data and linear appraisal data into an index where 0 equals the breed average, positive numbers are above average, and negative numbers are below average scores. Negative numbers aren’t necessarily bad because the average is only the average of goats who participate in milk test and linear appraisal. These tend to be goats in herds focused on performance and improving the breed. The best of the best. Having a negative PTI is better than no PTI at all in my opinion!

To get a PTI number, a doe needs to have a linear appraisal score and be on milk test through at least 40 days fresh with at least one other herdmate on test at the same time. Comparing the performance of herdmates is important because herd management and local climate have a large effect on production. Milk test data up to and including a doe’s 6th lactation is used. All linear appraisal scores are used. It is possible for a doe to get a PTI without being on milk test if many immediate relatives have milk test data.

There are two forms of PTI:

2:1 ranks milk production twice as important as linear appraisal (type) scores
1:2 ranks linear appraisal (type) scores twice as important as milk production

A goat earns its SG designation by being in the top 15% of either form of PTI.

Important to Note: PTI numbers are NOT based solely on a goat’s own milk production and linear appraisal scores. The production and scores of all of its immediate relatives with data on file are used in the calculations. A PTI number reflects the genetic potential of a goat based on both its own performance and that of its immediate family members.

How does a buck get a PTI?

A buck receives a PTI number when 3 daughters have appraisal scores and 5 daughters have been on milk test through at least 40 days fresh.

What is ETA (Estimated Transmitting Ability)?

A goat gets an ETA if both parents have a PTI. The ETA is just the average of the parents’ PTI numbers. It can be useful to see what a goat’s genetic potential is before it has been bred. Young bucks with high ETA numbers are recognized in the Young Sire Development Program.

What is PTA (Predicted Transmitting Ability)?

The average genetic value for a certain trait that an animal transmits to its offspring. Again, this is not based on just that goat’s data. The data from all of its immediate relatives are also used in the calculations.

Production:

The PTI calculation uses the PTA for fat corrected milk and is expressed in pounds of milk. A PTA score of 0 means a doe (or a buck’s daughters) is expected to produce the breed average. A PTA score of 95 means a doe (or a buck’s daughters) is expected to produce 95 more pounds than the breed average. A PTA score of -83 means a doe (or a buck’s daughters) is expected to produce 83 pounds less than the breed average.

Type:

The PTI calculation uses the PTA of just the final score, not the 13 linear traits. It is based on standard deviations from the breed average. Only doe scores are used in genetic evaluations. Buck scores don’t count for anything. Just bragging rights.

What is Fat Corrected Milk?

It’s a method to combine volume and butterfat percentage into one number to make comparisons between animals easier. Correcting to 4% is common practice and the formula is: (0.4 x pounds of milk) + (15 x pounds of fat). For example, if Goat A produces 1,000 pounds of 5% milk (50 pounds of fat) and Goat B produces 1,500 pounds of 3% milk (45 pounds of fat) and we “fat corrected” their milk to 4%, Goat A would have 1,150 pounds and Goat B would have 1,275 pounds.