We all know that fertility has a big impact on the bottom line. It directly affects the number of calves we have to sell each year. Beyond that, it actually changes the composition of our herd.
In most cases, we cull or sell open females. Thus, lower herd fertility forces us to keep or buy more replacement females. These young replacement females cost more to maintain. They re-breed at lower percentages, and they produce lighter calves. Because of these effects, herds with high replacement rates and low fertility are less profitable.
When we think of things that affect fertility, we don't usually think about genetics, however. First, we probably think about nutrition, cow body condition and perhaps diseases that affect fertility. The surprising reality is that genetics have a large effect on fertility.
But, when we talk about the genetics of fertility, we have to break it down into heifer pregnancy and cow pregnancy. This column deals with heifer pregnancy while next month's article deals with cow pregnancy.
Heifer Pregnancy Heifer pregnancy is the probability (or odds) that a heifer will breed as a yearling. This has a lot to do with her age at puberty (whether she is cycling yet), her weight and her inherent ability to become and stay pregnant.
Most operations feed heifers up to a level where they will achieve a certain pregnancy goal. If you're targeting 90% pregnant, then you learn that your heifers must reach a certain age and body weight to consistently get this type of result. Where do genetics come in?
To see the effects clearly, let's divide heifers from one herd into sire groups. Since the heifers are all raised with the same feed and same environment, we would perhaps expect to see that all of the bulls' daughters have the same pregnancy rates. In fact, the data shows dramatic differences.
This example is real. Data from the Red Angus Association of America (RAAA) indicates there are large, heritable differences between the pregnancy rates of different bulls' daughters raised under the same environment. If a pregnant heifer is worth $150 more than an open heifer, then Bull B's daughters are worth $66 more to the producer than Bull A's daughters. I think this is a conservative figure.
Clearly, extremely good management could mask the differences. If you get a 100% pregnancy rate, then no genetic differences are expressed. That does not mean that they are not there.
What if you saved a little money and fed your heifers less or bred them earlier to get a heavier calf? Then, your pregnancy rate would drop and the genetic differences would come out again.
In practice, the optimum profitability point for heifer pregnancy rate is usually not above 90%. If your pregnancy rate is that high, then you probably fed the heifers too much. By selecting for heifer pregnancy, we can decrease our feed inputs and still end up with the same pregnancy rates. This can significantly reduce the cost of raising replacements.
All this is possible. Although breed associations haven't normally collected this kind of pregnancy data, that may be changing. In September, the RAAA released its first heifer pregnancy EPDs on many of the breed's bulls.
Keep in mind, these first-time EPDs are low in accuracy; they are based on data from a limited number of herds that submitted pregnancy data to the RAAA. But, I expect more breeders and breed associations to develop this kind of useful data in the future.
As with all new EPDs, some bulls win and some bulls lose. The top bull in the Red Angus breed has a +15% EPD, and the lowest bull has a -15% EPD. This means if you bred a set of heifers with a 70% average pregnancy rate, then the top bull's daughters would hit 85% while the bottom bull's daughters would hit 55%. This is a huge difference.
Like any other trait, we should not select for this trait alone. But, if two bulls are equal on other traits, and one has a higher heifer pregnancy EPD, then I would pick the higher fertility bull for use in my herd.
The American Optometric Association (AOA) offers these tips to help prevent eye injuries:
- Wear wrap-around safety goggles made of polycarbonate. Look for labeling that says the goggles meet the American National Standards Institute (ANSI) Z87.1 standard.
- Don't rely on ordinary prescription glasses for protection.
- Prolonged exposure to ultraviolet light can cause cataracts and contribute to age-related macular degeneration. Wear sunglasses that block 99-100% of the sun's UV-A and UV-B ultraviolet radiation.
- Sunglasses aren't dark enough if you can see your eyes through the lenses. Gray tint lens won't distort color perception.
- Before welding, put on a face shield made for welding. Each year, more than 14,000 eye accidents related to welding are reported.
If eye injury occurs, apply these emergency care procedures, then seek immediate treatment:
- For chemical splashes, flood the eye non-stop with clean water for 15 minutes. For alkaline burns (such as lime, lye, ammonia), irrigate the eye for 30 minutes.
- For blows to the eye from a blunt object, lightly apply a cold compress. Don't wash, rub or apply pressure, even to stop blood flow.