ESTIMATED BREEDING VALUES (EBVS) & INDEXES
Bull selection can have a huge impact on your profitability, which is why we use
EBVs to measure the genetic potential of an animal in specific traits and have
confidence around that selection process.
If we wanted our female progeny to conceive earlier and have calves more frequently, choosing a bull with a Days to Calving EBV of -5 days would be expected to produce daughters that conceive earlier in the joining period than the daughters of a bull with a Days to Calving EBV of +5 days.If we wanted to know what a bull’s calves might weigh at 600 days, we look at his EBV. If he has a 600D weight EBV of +50, we halve this figure, telling us that his progeny will be 25kg heavier at 600 days old than the progeny of a bull with a 600day EBV of 0.BRAHMAN EBV TRAITS: OVERVIEW
| EBVS | EXPLANATION | IMPACT | SELECTION USE |
|---|---|---|---|
| Gestation Length (days) | The lower the number the shorter the gestation length | Length of gestation period | Selection for a shorter gestation period, can result in better chances of re-breed and calves that are born earlier and more easily. |
| Birth Weight (kg) | The higher the number the higher the birthweight of the calf | Size of the calf at birth | A Sire with a smaller value will produce smaller calves, potentially easing calving difficulties |
| 200 Day Weight (kg) | The larger the number the more favourable | Growth rate | A Sire with a larger value will produce progeny that will be heavier at 200 days. |
| 400 Day Weight (kg) | The larger the number the more favourable | Growth rate | A Sire with a larger value will produce progeny that will be heavier at 400 days. |
| 600 Day Weight (kg) | The larger the number the more favourable | Growth rate | A Sire with a larger value will produce progeny that will be heavier at 600 days. |
| Mature Cow Weight (kg) | The larger the value the heavier the live weight of the cow at 5yrs of age | Mature size | Larger animals have a higher maintenance requirement. Smaller animals will have lower cull cow value. A moderate value will maximise growth of progeny whilst maintaining the mature size of the cow. |
| Milk (Kg) | Higher values indicate more productive milking females | Milking and calf rearing ability | Can be used to select for female breeding lines that will produce more milk and produce heavier calves. |
| Scrotal Size (cm) | The larger the number the larger the testicles at 400 days of age | Scrotal circumference, reproductive maturity | The larger number the larger the male progeny's testicle size as a yearling and the younger the female progeny's age of puberty (e.g. larger = earlier). |
| Days to Calving - DTC (days) | The lower the number the earlier in the calving season the cow should calve. Lower the number the more favourable | Time between joining and calving | Selecting a Sire with a low value will produce female progeny which conceive early in the joining period. Females with low figures typically show early puberty. |
| Carcase Weight (Kg) | The higher the value the more favourable | Hot standard carcase weight at 650 days old | Choosing a sire with a higher value would produce projeny with a heavier carcase weight - NB: not an indicator of yield. |
| Eye Muscle Area - EMA (sq. cm) | The higher the value the larger the eye muscle area | Size of eye muscle area relative to carcase weight | Selecting for higher values will result in progeny with larger eye muscle area relative to the carcase weight. |
| Rib Fat (mm) | The lower the value the leaner the carcase, measured at the 12/13th rib site. | Leanness of the carcase | Selecting for lower values here = a smaller, leaner carcase, enabling the animal to be taken to a heavier weight without becoming overfat.Breeding objectives should be considered carefully here. |
| Rump Fat (mm) | The lower the value the leaner the carcase, measured at the P8 rump site. | The % of saleable beef relative to carcase weight | Selecting for lower values here = a smaller, leaner carcase, enabling the animal to be taken to a heavier weight without becoming overfat. Breeding objectives should be considered carefully here. |
| Retail Beef Yield - RBY (%) | The higher the value the more favourable | Meat marbling | Typically selecting for a higher value will result in progeny which produce a larger quantity of saleable beef. |
| Intramuscual Fat - IMF (%) | The higher the value the more marbling, measured at the 12/13th rib site | Fertility | Selecting for higher scoring animals will produce higher carcase marbling - desirable for some markets where marbling is important. |
| Percent Normal Sperm - PNS (%) | Measured at 600 days. Indicates percentage of sperm which have no defects. The higher the value the more favourable. | Fertility | Selecting for larger values will produce sons with higher PNS, therefore more fertile, and earlier maturing. |
| Flight Time (secs) | The higher the value the 'quieter' or 'more docile' the animal. | Temperament | Selecting for higher values should result in progeny with a good or better temperament. |
| Shear Force (Kgs) | The lower the value the more favourable. (the force req. to pull a blade through a piece of cooked meat) | Meat tenderness | Selecting for a lower score will result in progeny with more tender meat characteristics. |
EBVs are also displayed in a chart which can be very useful for a quick visual on where that animal sits.
Bars to the right of the middle represent that the EBV/ Index is above breed average (superior). The further the line is to the right, the better.
Bars to the left of the middle indicate that the EBV/ Index is below breed average (inferior). The further the line is to the left, the worse. (Except DTC, FT & Shear Force, Birth Weight)
ACCURACY %’S
For every EBV value provided we are also given an accuracy value. This is telling us how much raw data has been used to calculate that EBV value (e.g. how many records have been submitted to Breedplan with direct genetic linkage to that animal). Therefore the higher number the more reliable the data and the smaller the chance of that EBV changing significantly over time.
INDEXES
EBVs are a great tool for helping in bull selection for individual traits. We all know however there is often more than one trait we would like to select for and these traits have an impact on each other. This is where Indexes can be helpful.
Indexes have been created specifically for the Brahman Breed and can be used to meet a specific breeding objective, these are;
- Live Export Index
- Central Production Index
