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Jan 20, 2007
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Previous issues of the BEEF Cattle letter

Issue # 581

April 2, 2008

Improving Cowherd Reproduction via Genetics, Part 1 of 2 - Wade Shafer, ASA Director of Performance Programs

A beef cow's job is not an easy one. She is expected to conceive at slightly over one year of age to calve by the time she is two and rebreed shortly after that while weaning a healthy, viable calf. Furthermore, we demand that she consistently repeats this cycle for the rest of her life - one stumble and, in the words of California's terminating governor, hasta la vista, baby!

To be sure, producers are best served when the cow successfully performs her task for many years, as the longer her productive life the more profitable she is to the enterprise. Is there anything that can be done to help her out? Certainly, there are environmental factors we can manage that will give her a leg up. For example, by providing adequate nutrition, a proper vaccination regimen and mating her to easy-calving sires (particularly when she is young) we increase the odds of her success. While a cow's environment has a substantial impact on her reproductive performance, her genetic makeup can too. This paper explores the genetics of female reproduction and offers suggestions on how to improve the reproductive performance of your cowherd via genetics.

Crossbreeding: The obvious place to start a discussion about the genetics of female reproduction is with the factor that far and away has the greatest affect on it - crossbreeding. It has long been recognized that crossbreeding enhances virtually all aspects of reproductive performance. Studies too numerous to list here have established the reproductive superiority of crossbred over straightbred cows.

In one of an abundance of studies with similar findings, scientists at the Meat Animal Research Center (MARC) concluded that two-breed rotational cross cows produced 20% more calves over their lifetime than straightbreds due to the favorable impact of heterosis on dam fertility/longevity and calf survivability brought about by the improved calving and mothering ability of the dam (Cundiff et al., 1992). Furthermore, they estimated that when mated to a bull of another breed the two-breed cross cows would wean 36% more weight over their lifespan than straightbred cows raising straightbred calves. The dramatic increase is attributable to the positive influence of heterosis on reproduction and production in the dam and well as increased growth and survivability in their calves.

Given the overwhelming evidence of the crossbred cow's reproductive supremacy and the fact that reproduction is a major piece of the profitability puzzle (by most accounts exceeding all other functions by a wide margin in relative importance), it is difficult to conceive of a situation where a commercial enterprise would not benefit financially from a crossbred cowherd.

Am I implying that selecting animals within a breed for reproductive performance is not a worthwhile endeavor? No! Reproductive progress can be made via selection (which I will address later); however, it would take years of intense selection within a breed to yield the kind of improvement that can be achieved in one fell swoop by simply crossbreeding.

Therefore, crossbreeding makes a logical cornerstone in any effort to enhance cowherd reproductive performance. With crossbreeding as the foundation, the selection of superior animals of multiple breeds as inputs to the crossbreeding system can be considered a supplemental means of further boosting reproductive function; however, identifying reproductively superior animals has its challenges, as I will explain.

Indirect Selection: Because the assessment of a cow's reproductive performance is generally determined later in her life, it seems logical to look for early indicators to hasten the process. For example, it is a commonly-held belief that females with a propensity toward fatness will excel reproductively.

Though research has shown that increased fatness, to a point, is strongly and favorably associated with reproductive performance on a phenotypic scale, the few attempts to assess the relationship on a genetic level show an unfavorable, though weak, relationship. Using data from the Red Angus Association of America (RAAA), researchers at Colorado State University (CSU; Beckman et al., 2006) derived genetic correlations ranging from -.12 to -.22 between body condition at various ages and stayability (by industry convention, the probability of a cow remaining in the herd through 6 years of age). At the American Simmental Association (ASA), we have found a correlation of -.19 between an animal's genetic propensity for backfat in the feedlot and their inherent stayability. We (ASA) have also calculated a -.11 genetic correlation between backfat and heifer pregnancy (the likelihood of a heifer being pregnant at the end of the breeding season) using RAAA data.

Admittedly, these unfavorable correlations between fatness and reproduction may seem illogical. We have all seen a higher proportion of thin cows open at pregnancy test time. Keep in mind, however, that the aforementioned correlations are genetic. The relationships we actually observe, i.e., phenotypic correlations, are influenced by a combination of underlying environmental and genetic relationships. There is little question that females within a herd lucky enough to experience an environment for increased body condition (e.g., extra energy intake) are likely to have better reproductive performance than their herd mates. Furthermore, this strong and positive environmental relationship between fat and reproduction apparently overwhelms what appears to be a slightly negative genetic relationship - yielding the strong, favorable phenotypic relationship we typically observe.

Frankly, there is not enough evidence about the genetic relationship between fatness and reproductive function to make recommendations based on it at this time; however, though it may fly in the face of conventional wisdom, it appears that selecting "easy-fleshing" genotypes will not gain us ground reproductively.

Scrotal circumference has been considered as a predictor of female reproductive performance. Though the preponderance of evidence indicates a strong to moderately favorable relationship between scrotal circumference and age at puberty in related females, research is less clear on the relationship between scrotal circumference and subsequent measures of reproduction. In a study based on a large population involving several breeds at the MARC, Martinez-Velazquez et al. (2003) found a slightly unfavorable (.15) relationship between scrotal circumference and age at first calving and no relationship between scrotal circumference and 1st pregnancy, 1st calving and 1st weaning rates. Their conclusion was that selection on scrotal circumference would not be effective in improving female reproduction. These findings are in agreement with some studies and contradicted by others. For those interested, Martinez Velazquez et al. (2003) provides and excellent literature review on the subject. Given the conflicting evidence, it may not be advisable to base selection decisions on scrotal circumference with the intent of enhancing maternal reproduction.

As for other traits that may be related to reproductive function, Rogers et al. (2004) found that increased levels of milk EPD increased the risk of females being culled. This finding is consistent with ASA data showing an unfavorable (-.15) genetic correlation between milk and stayability. Other ASA genetic correlations of note: -.26, .40, and -.19 between stayability and mature weight, maternal calving ease and marbling, respectively. Based on these findings, we would expect females that are inherently lower milking, smaller mature sized, easier calving and less marbled to stay in the herd longer; however, none of these relationships are strong enough to make a sizable impact on stayability by selecting for them. Furthermore, other than mature weight because of its strong relationship to early growth, determining the genetic level of a young heifer for these traits by simply observing them (which is what most commercial producers are limited to) is not possible. Therefore, a different tack will be required if we wish to improve reproductive performance via selection. Namely, select for it directly - which, as I will point out, is not a trivial task.

Next week, Part 2 of this article begins with a focus on Direct Selection.

EDITOR's NOTE: Improving cowherd reproduction via genetics will be but one concept Dr. Shafer will focus on during the Ohio Beef Cattle Breeder Conference being hosted on the campus of The Ohio State University by Dr. Tom Turner and staff of the American Simmental Association on April 30 beginning at 3 p.m. The overall theme for the day will be utilizing all the available tools to make better cattle and better beef. Find more details regarding this futuristic program in coming issues of this letter. The program is free, but reservations are requested and may be made by contacting Stan Smith at [email protected] or 740.653.5419 X 24.

Forage Focus: Re-seeding/renovating Pastures - Rory Lewandowski, Extension Educator, Athens County

Between last years drought that lead to overgrazing of pastures, and the late fall/winter rains that kept soils saturated and lead to trampled pastures turning into mud, there is a need on many farms to re-seed or renovate at least some pasture paddocks. Like every other input cost, the price of grass and legume seed has increased. What are the options to get these abused pasture paddocks back into a productive forage? In this article I will present several options and management strategies that can be considered.

One low cost option, at least in terms of out-of-pocket expenses, is to do nothing. Nature abhors a vacuum; something will re-grow in these muddy, trampled paddocks if given enough time. The cost in this option is time. If you have the land base to set aside those torn up paddocks through the spring and early summer, they will renovate themselves. We generally have plenty of seed bank in the soil. Whether that seed bank contains desirable plants, or what percentage of desirable plants will make-up the re-growth are questions to be considered. It is likely that in those paddocks where the sod base was torn up, that summer annual species like pigweed, ragweed, barnyard grass and goose grass will show up in heavy numbers in addition to the grasses and clovers that had been present in the sod base. Clipping the summer annual weeds off before they go to seed will allow more light into the grasses and clovers that are coming back. By mid to late summer a light grazing pass could be made on these paddocks. If they are not tore up again in the next winter, the sod base will continue to thicken and good rotational grazing management can put them back into productive pasture paddocks the following year. The main question that must be answered in this option is; do you have the time and land resource base to be able to wait for the paddock to heal itself and lose a grazing season of productivity?

The next option to consider is seeding. Seeding offers the possibility to increase pasture productivity and to bring a new mix of forages into the pasture paddock. When Bob Hendershot, NRCS State Grasslands Specialist, spoke to the Athens area grazing council in early March, one of the points he made related to pasture genetics. Bob pointed out that row crop producers use new and improved genetics to increase crop yields, as livestock producers we seek to improve our livestock genetic base, but we don't give that same attention to pasture genetics. Bob asked, "How old are the genetics in your pasture forages?" There have been advances in forages; grasses and legumes bred to better tolerate grazing, genetics that allow plants to be more palatable and productive. A sacrifice paddock that was overgrazed during last year's drought and/or tore up during this winters soggy conditions may be an opportunity to bring some new and improved forage genetics into the pasture mix.

Talk with your seed representative about a pasture mix or give me a call here at the Athens County Extension office to talk about specific species. As we look at nitrogen prices, I would encourage all graziers to aim for a 30% evenly distributed legume species throughout a grass stand. At this level supplemental fertilizer nitrogen should not be needed. If the area to be planted needs to get a quick cover due to erosion concerns and/or some quicker production is needed for grazing, then include some annual ryegrass seed in the seeding mixture. Adding around 4 pounds of annual ryegrass/acre should provide some early cover and an early grazing pass because it is quick to germinate and grow. If you decide to seed, line up your seed supplies as soon as possible, there have been rumblings about some forage seed shortages in the coming year. As I have talked with some seed representatives the shortages are not across the board, but more likely for certain species or varieties within species.

Once you decide to add some new forage seed to your pasture paddock, how you answer the next question may determine when you plant that seed. What is the soil pH and what are the soil fertility levels in the paddock you intend to seed? Seed is not cheap and buying the new and improved grass and legume genetics will cost you more than older genetics. Make sure that seed, once planted has a chance to become a productive plant and maximize its genetic potential. That begins with soil pH and soil fertility. Soil pH should be above 6.0, with a goal of 6.5. Soil phosphorus (P) level should be at 25 ppm and in Athens County, given our average cation exchange capacity (C.E.C.); soil potassium (K) level should be 100 to 120 ppm. If your soil is not close to these numbers it may be worthwhile to put off a spring seeding, apply the needed lime and fertilizer this spring and aim for a late summer seeding. In those paddocks that are severely tore up, it offers the rare opportunity in a pasture situation to spread lime and/or fertilizer and then use tillage to incorporate it into the root zone while smoothing out the soil surface and preparing a seed bed.

According to the Ohio Agronomy Guide, a spring seeding should be completed by April 20 to 25. Earlier is better. As we move past mid-March frost seeding is no longer a seeding method option, and in any case is not a good seeding method for grasses. That leaves us with conventional drilling, use of a no-till drill or a broadcast seeding following by some type of cultipacking. The key concepts to keep in mind any time a forage seeding is made are:

* Reduce weed or sod competition for the new seedling. This relates to soil preparation. If the pasture paddock has been excessively trampled and tore up, it may only be necessary to do some leveling off of the ruts before running a drill over the paddock. Broadcasting the seed and then running a cultipacker over the surface can also work well. When broadcasting seed, consider seeding half the rate length-wise over the paddock and then the other half cross-wise over the paddock to get better seed distribution. On a sod base, make sure the forage has been grazed down tight, down into the soil surface. A no-till drill works well in this situation. If the sod is thin, but has not been able to be grazed down tight before seeding, then application of an herbicide to kill the sod back should be considered. Application of glyphosate 7 to 10 days before seeding can be used.

* Do not seed too deep! Many stand failures can be traced back to planting the forage seed too deep. Seed should be planted about one-quarter of an inch deep. It is better to err on the side of planting shallower rather than deeper.

* Pay attention to seeding rates. For example, according to the Ohio Agronomy guide an orchardgrass, red clover, and white clover mixture would be seeded at a per acre rate of 7 pounds of orchardgrass, 4 pounds of red clover and 2 pounds of white clover on a pure live seed basis. Check the label to determine the percentage of pure live seed and adjust seeding rates accordingly. In our example if orchardgrass had a pure live seed percentage of 85, and red clover and white clover had a pure live seed percentage of 70, then our actual seeding rate per acre of these seeds are: 8.25 lbs of orchardgrass, 5.75 lbs of red clover and 2.85 lbs of white clover. Calibrate the seeder!

* If the specific legume species you are planting has not been in the pasture paddock for a few years, make sure the seed is inoculated with the correct rhizobial bacteria to insure the plants will be effective in fixing nitrogen. Sometimes, legume seed will come with a coating that contains the rhizobial bacteria. Be aware that this coating changes the seeding rate. Generally you will have to seed more pounds per acre of this coated seed to get the targeted non-coated seed rate. Read the label and calibrate the seeder!

It takes about 6 to 8 weeks for a new seeding to become established. Ideally the new seedlings can develop a good root system while soil moisture is plentiful and before summer temperatures arrive. This is the reason behind setting the spring seeding date target around April 20th. After the seeding has emerged and begun to grow and once the grass plants get about 6 inches tall, it is beneficial to the stand to either do a clipping or a light grazing pass that takes off the top couple of inches. This will allow light to get down to the young clover seedlings so they get better growth and the clipping/grazing will also stimulate tiller formation in the grass seedlings. Do not graze or clip off the young clover seedlings. After about 8 weeks of growth, or towards the end of June, begin to manage the stand using good rotational grazing principles.

In some cases it may be advantageous to delay the planting until late summer. The target dates for a late summer seeding are mid to late August. Reasons for this delay may be to improve soil pH and soil fertility levels before the perennial seeding, or reduce competition pressure from weeds or an aggressive fescue sod base. This does not mean that this paddock must remain unproductive during this time. A short term crop can be planted that will provide some summer grazing while helping to reduce weed pressure and/or kill back a fescue sod. This might be the place to use annual ryegrass. As mentioned earlier in this article, it germinates fast and provides the quickest grazing of our grass options. It needs to be managed to prevent it from going to seed, so frequent, short duration grazing passes work. Another option in this scenario is to seed a forage turnip during April, possibly along with a cereal grain like winter wheat. In about 6 weeks there should be high quality forage to graze. Under rotational grazing principles, you might get a several grazing passes before the mid to late August summer seeding of your perennial grass/legume mixture. A third option would be to seed a sorghum x sudangrass hybrid or brown mid-rib variety of sudangrass in the later part of May. The tall, vigorous growth out competes a fescue sod base while providing a high tonnage, good quality forage that will be ready to graze before mid-July. Under good rotational grazing principles, several grazing passes can be made before it is time to make the late summer seeding.

There are options available that allow beaten up pasture paddocks to recover and become productive grazing paddocks again. The specific option chosen depends upon the resource base of the producer, farm forage goals, and timing. Regardless of the option used, planning, management and some cooperation from Mother Nature are necessary to achieve success.

Weekly Roberts Agricultural Commodity Market Report - Mike Roberts, Commodity Marketing Agent, Virginia Tech

LIVE CATTLE futures on the Chicago Mercantile Exchange (CME) were mostly gainers on Monday. The APR'08LC contract closed at $87.425/cwt, off $0.225/cwt and $1.800/cwt lower than two weeks ago. JUNE'08LC futures were down $0.125/cwt at $87.750/cwt and $2.230/cwt lower than Monday before last. The rest of the back months were gainers but all contracts lost some ground on pressure from increasing corn prices and short covering near the close. USDA reported a large hog supply which competes with beef for meat protein. Lower cash sales also prompted some selling. The USDA 5-area price was $1.00-1.80/cwt lower than this time last week and $7.50-$8.00/cwt lower than this time last year. It has been reported that feedlot losses were estimated as much as $150.00/head last week. USDA placed last week's sales figures for the Texas/Oklahoma area at 41,611 head and in Kansas, almost 32,000 head were sold. USDA on Monday put choice beef cutout at $138.22/cwt, up $0.83/cwt. Select prices aren't usually reported in this report but are still running close to choice at $137.88/cwt meaning folks are still buying cheaper cuts of meat in this shaky economy. Demand for fat cattle is expected to remain at a lower level because of sustained negative packer margins. According to HedgersEdge.com, the average beef plant margin for Monday was estimated at a negative $28.80/head but this is $1.05/head better than this time last week. Packers were estimated paying $89.28/cwt vs. an estimated breakeven buy of $86.99/cwt. In addition, higher fuel prices are affecting transportation costs and buyers are just not as willing to pay up for the cattle. Problems with exports from South America could provide openings for U.S. beef in Asian markets. Cash sellers should sell cattle on any rally. Hopefully corn inputs were priced on last week's slide. If not, it will probably be another two weeks before any significant opportunity to price corn may come along.

FEEDER CATTLE at the CME were down across the board on Monday. The APR'08FC contract finished at $99.300/cwt, down $1.125/cwt. MAY'08FC futures were down $1.050/cwt at $101.225/cwt. Losses could have been steeper but were limited on end-of-session-profit-paring in the CBOT corn pit. I'm writing this report from Oklahoma City and passed the Oklahoma City cattle market on the way in to town from the airport. It was reported that cash feeders in Oklahoma City were $2.00-$2.50/cwt lower after starting out a shaky $5.00/cwt lower then recovering later in the day. There didn't seem to be a lot of feeder cattle trading today. Feeder buyers are finding it difficult to keep things together right now. It seems that everything is coming together to pressure them. Gregg Doud, Chief Economist for the National Cattlemen's Beef Association said it well. It is the perfect storm for the cattle business because of higher input costs, lack of market access to Japan and Korea, increased pork supplies and the troubled U.S. economy. This is unprecedented." I agree. One analyst has estimated that feeders are losing up to $200.00/head. The latest CME Feeder Cattle Index for March 27 was placed at $99.68, down $0.02/cwt but $0.66/cwt better than this time last week. Feeders don't look like they will recover this week on weak demand and surging corn. It might be a good idea to go ahead and push sales if adequate corn inputs were not bought last week.