Objective and Subjective EBV’s and what they mean…….
The first thing I would say is that EBV’s are a tool and are no substitute for visual appraisal. In addition it is important to know which EBV’s are objective (actually measured) and which are subjective (in the eye of the beholder).
Indexes are another story.
They combine a range of objective and subjective measurements into a single dollar figure. The magic bullet number, so to speak. You will see we do not have index values on our highlighted EBV sheet. This is because I don’t believe in a one number fits all type scenario. Do these indexes compare a farmer who gets 400 mm annual rainfall on granite country that also has a fine wool sheep operation with a farmer who get 900 mm on basalt country and specialises in angus cattle only?
No they don’t.
I strongly believe that EBV’s add some value as long as you know which ones have a strong tie to the needs of the profitability of your individual beef business. Indexes don’t and are a trap for the unwary.
The EBV’s that I consider to be the most objective (if measured properly) are:
- Gestation length – based on known A.I. or joining dates
- Birth Weight – actually weighed within 24 hours of birth
- 200, 400 and 600 day weight – actually weighed at those average ages (but would be more relevant if they came with a hip height at weaning)
- Scrotal size – measured at semen testing
- EMA – scanned at 600 days
- Fat – rib and rump – Ultra sound scanned at 600 days
- IMF – scanned at 600 days (true marbling develops given age and grain but this is an indication)
To keep it simple I think there are a few traps that need to be avoided.
THE MATURE COW WEIGHT IS IRRELEVANT WITHOUT A FRAME SCORE.
One clear trap that has become critical at this time of herd rebuilding is tied to Mature Cow Weight (MCW). MCW is measured by weighing cows at the time they wean their calf. Unfortunately, it does not take into account frame size. So to me it is a rather irrelevant figure. You can have a lean, tall, hard doing cow that weighs the same as a fleshy moderate easy doing cow. I know which animal I would prefer.
If you chase high growth numbers by themselves you will end up with high birth weights and your cow herd will become large framed and high maintenance. This will lead to lower fertility when the season or conditions get a bit tough. When is big enough enough?
Positive fat is also important in the equation. It is not a negative as some people believe. With positive fat the result is usually a moderate, fleshy, easy doing cow herd that is fertile, calves easily and gives progeny that still powers on muscle and Again a good average is what you want if your herd is easy fleshing but bump it up to add that softness.
If you chase marbling be prepared to end up with cows that are, I guess, wagyu like. Harder doing, angular and in the case of angus cows bred this way, harder calving and less fertile. Our experience with the years of owning our own branded beef product showed us that Angus cattle marble adequately.
Soft easy doing angus that are moderate and fleshy provided us with the juiciest tenderest eating experience. Our product marbled scored predominately 3 and 4 on the MSA grading at 16 to 18 months of age at a carcase weight of 330 kgs. So be careful of chasing marbling.
The milk EBV is a good one to understand or things can get unruly. If you target the big milk figures you could easily find yourself with cows that can’t find enough food to support the milk habit if you have tough country and she suffers and may not rebreed. Or over supply if you have high rainfall improved pastures and this is a big problem with scours and mastitis etc. Don’t forget that the average milk today of +17 was running at an average of +12 ten years ago. Our average milk EBV then was adequate so just keep in mind the creep.
EBV’s are a bit of a mine field for commercial producers.
With 17 individual main EBV’s and 4 indexes it’s no wonder that confusion reigns.
I think it is very important to understand the implications attached to relying solely on EBV’s when making your bull buying decisions. I feel strongly that indexes are a real problem. To break down an animals potential to one number is frankly an insult to cattlemen’s intelligence and to the cattle themselves.
To finish the discussion on EBV’s I have to say that within the angus breed there are the full range of genetics that can produce on one hand, very maternal, soft, easy doing mother cows that are efficient converters of feed into pregnancies, live calves and heavy weaners or yearling sale cattle. On the other hand there are some that are big, inefficient terminal type angus that have to be feedlot finished for 250 plus days and who’s mothers stop breeding when the going gets tough. It is important to know which direction you are going to take if you are to use EBV’s as your sole selection method. Don’t forget the E in EBV’s means estimated!
I hope this all encourages you to reflect and has at least given some food for thought.