Selecting Meat Goats Using Performance Data

One of the best ways to compare individual goats is by using data. Producers collect these data starting when kids are born and add information throughout a doe's or buck's life.

When selecting goats based on data, there are two options: EBVs and individual performance within a herd. EBVs are the preferred selection parameter because these numbers focus on genetic estimates for performance across a breed. EBVs are measurements of heritable traits such as number of kids born, weaning and post-weaning weights, and carcass traits. While an individual's performance within a herd is still useful information, the performance of that individual will be influenced by management and environmental factors in addition to genetics.

The National Sheep Improvement Program (NSIP) uses data collected on a farm and makes genetic connections to other herds through a database in Australia known as LambPlan. This database uses a record-keeping software called Pedigree Master to submit data for LambPlan. Participating in the EBV program helps producers improve genetic predictability in order to produce a more consistent product, which could be breeding stock or meat for customers.

In addition, records allow producers to make informed decisions for both selecting replacement animals and for culling poor-performing animals. This is especially important for identifying animals within the herd that do not produce offspring that meet minimum production standards. Producers can also utilize records on progeny to make culling decisions once does and bucks produce offspring. Performance data collected on individual goats can be interpreted at the farm level or can be sent to NSIP to develop EBVs.

Common Performance Data Collected by Producers

Birth weight
Most kids should weigh between 5 and 8 pounds at birth, depending on the mature size of their parents. Larger kids may cause kidding difficulties, while smaller kids may require producer assistance for the first few days after birth. This adds to the labor requirements at kidding and can increase the likelihood of death losses.

Birth date
To best manage groups of does and kids, does in the herd should give birth as close to the same date as possible. A good goal is for all kids within the herd to be born within two heat cycles, or 42 days. Kids born outside this 42-day window often weigh less than the average at weaning. Producers should consider culling does that do not kid within this timeframe.

Birth Type and Rearing Type
Birth type refers to kids born as a single, twin, or triplet. To be profitable, many operations need their does to produce twins and does should rear those kids as twins. Yearling does are the exception, as most will produce a single kid. Selecting bucks, as well as does, born as twins can help boost the genetic likelihood of twinning. But nutrition also plays a large part in twinning rates. Boosting the plane of nutrition during the breeding season, also known as flushing, can have a major impact on the likelihood of twinning.

Weaning weight
Many kids in the northeast are sold at weaning, so heavier weaning weights can increase the profitability of an operation. A good goal is to have meat goat kids weigh 35 to 50 pounds or more by 90 days of age. However, this is not a realistic goal for all breeds.

Kids born as singles normally weigh more at weaning than kids born as twins or triplets. Other factors, such as the sex of the kid and the age at weaning, also influence the weaning weight. Keep in mind that a pair of twins will most likely weigh more at weaning than the single kid. Thus, the weight of the pair, even if its individuals weigh less than the single born kids, determine the income produced by the doe.

Adjusting Weaning Weights

As alluded to earlier, animal performance is based both on genetics and the environment. Producers can adjust weaning weights in order to compare individual kids born on the same farm, since these animals have theoretically all been exposed to the same environmental conditions.

Weaning weights can be adjusted for:

• age at weaning
• birth type (single, twin, or triplet)
• rearing type (single, twin, or triplet)
• sex of the kid
• age of the dam or mother

To adjust for the age at weaning:

1. Determine an age to adjust to. Weaning weights are typically adjusted to 90 days of age, but could also be adjusted to other ages, such as 60 or 120 days of age.
2. Subtract the birth weight from the weaning weight. This is the weight gained.
3. Divide by the age of the kid (in days) when it was weighed. This is the average daily gain.
4. Multiply the average daily gain by the weaning age you are adjusting to (usually 90 days).
5. Add the birth weight.

Estimated 90-day weight = (((weaning weight – birth weight)/age at weaning) X 90) + birth weight.

The estimated 90-day weight can then be adjusted for more factors. The following table lists adjustment factors to account for the age of the doe, sex of the kid, birth type, and rearing type.

* Type of birth and rearing:
1/1 = single raised as a single
1/2 = single raised as a twin
2/1 = twin raised as a single
2/2 = twin raised as a twin
3/1 = triplet raised as a single
3/2 = triplet raised as a twin
3/3 = triplet raised as a triplet

Notter, D. 2008. The 2007 Boer Goat National Genetic Evaluation. Boer Goat Improvement Network Notebook, No. 4, National Sheep Improvement Program, Centennial, CO, 15 pp.

Example of Adjusting a Weaning Weight

A twin doe kid was born on January 2nd, weaned on April 4th, and was raised as a twin. The dam is 2 years old.

Birth weight = 7 lbs.
Weaning weight = 45 lbs.
Actual age at weaning = 91 days
Weaning age to adjust to: 90 days

1. Adjust the weaning weight for 90 days. Use the following formula: Estimated 90-day weight = (((weaning weight – birth weight)/age at weaning) X 90) + birth weight (((45-7)/91) X 90) + 7 = 44.58 lbs.
2. Now adjust the weaning weight for doe age, sex of the kid, and the type of birth and rearing, by multiplying by the adjustment factors found in the table: 1.09 = adjustment factor for a 2-year-old doe 1.11 = adjustment factor for a doe kid 1.18 = adjustment factor for a twin raised as a twin

44.58 lb. X 1.09 X 1.11 X 1.18 = 63.65 lb.

Therefore, the adjusted 90-day weight of this doe kid is 63.65 lbs. This calculation allows producers to better compare kids and make more informed selection decisions.

Using Estimated Breeding Values

In order to compare the genetics of animals from one farm against those from another farm, meat goat producers can utilize estimated breeding values or EBVs. The National Sheep Improvement Program uses data collected on a farm and makes genetic connections to other meat goat herds through a database in Australia known as LambPlan.

According to the National Sheep Improvement Association website, "EBVs are science-based, industry-tested measurements of heritable traits that can be tracked and measured. For those familiar with Expected Progeny Differences (EPDs) used in cattle, EBVs are very similar. EPDs denote the estimated breeding value of an individual animal's progeny, whereas EBVs denote the estimated breeding value of the individual animal. More simply, EBVs equal EPDs times two."

Through these EBVs, producers can assess the genetic merit of their animals for a number of different traits. This helps producers improve genetic predictability in order to produce a more consistent product for their customers. These products include breeding stock and meat products. To find out more about this program, visit NSIP website.

Closing Comments

Producers should first select meat goats based on performance data and then use visual appraisal to assess additional factors such as structural correctness. Using these two practices together can help promote performance and production within a herd and lead to a more profitable operation.