Scrotal Circumference (SC) Measured in centimeters, SC predicts the difference of scrotal circumfer- ence of an animal’s male offspring at a year old. Older age at puberty has been linked to lower conception rates and later calving dates in females, a reduction in the quality and quantity of semen produced by bulls, and poor performance in several other measures of reproduction and fertility. SC has been found to be a good indicator of age at puberty, and is a high- ly heritable trait favorable to selection. SC is especially important to con- sider in herds where heifers will be retained. Keep in mind, a favorable SC is not a replacement for a breeding soundness exam! Stayability (ST) ST predicts the genetic difference in terms of probably that a female will stay productive in the herd until age six. These are calculated from calv- ing and pedigree information. ST is one of the best measures to compare a bull’s ability to produce females with reproductive longevity, and helps producers sort out genetic differences from environmental differences. Docility (DOC) EPDs for docility help to predict cattle temperament, with a higher value indicating calmer behavior, and lower values suggesting more nervous or aggressive tendencies. It is important that offspring are scored as 1 (docile) or 2 (restless) as opposed to 3,4 5, or 6 (nervous to very aggres- sive). Docility directly affects how easily animals can be handled, man- aged, and processed. Carcass Weight (CW) CW EPDs expressed in pounds are a predictor of the differences in hot carcass weight. Ribeye Area (REA) REA EPDs expressed in pounds are a predictor of the differences in ri- beye area.
Expected Progeny Differences (EPDs) are used to compare the genetic merit of cattle for specific traits, and can aid in making selection decisions for desired traits in the herd. An EPD helps to predict the difference in performance of the future offspring of a parent. They are based on data from the animal’s pedigree, performance, and performance of its relatives and offspring. It is important to remember that the performance of an ani- mal is determined both by genetics and environment, and EPDs help to predict differences due to genes passed from parents to offspring. When additional DNA information is available (testing through a 100K panel), accuracy of EPDs is improved. By combining performance, progeny data, as well as pedigree and genomic results, we can best estimate an animal’s genetic value as a parent. Another fundamental concept of interpreting EPDs is to recognize that EPDs serve to rank animals. By comparing an animal’s EPD for a given trait to the average EPD of all animals, one can determine if the animal is above or below average. By familiarizing yourself with percentile rankings, you can determine the degree to which an animal is above or below aver- age for a given trait. The Limousin and Lim-Flex percentile ranks are available on the Digital Beef registry platform on the left hand menu under Cattle Evaluation. Calving Ease Direct (CED) and Calving Ease Maternal (CEM) The Limousin breed has an excellent reputation for calving ease and asso- ciated calf vigor and survivability. But even low levels of calving difficulty can mean increased veterinary and labor costs, calf death loss, susceptibil- ity to disease, mortality, delayed return to estrus, and lower conception rates. Higher calving ease EPDs are favored and indicate genetics for greater chances of unassisted births. The calving ease direct (CED) EPD is important for choosing which sires to breed to first calf heifers to produce calves that are born easily. The calving ease maternal (CEM) EPD is in- dicative of greater calving ease in bulls’ two-year-old daughters Birth Weight (BW) Birth weight has been identified as the single most influential factor con- tributing to calving difficulty. Birth weight is used in the calculation of Calving Ease Direct. Lower birth weight EPDs indicate lighter progeny birth weights, which generally should translate into less potential for calv- ing problems. Weaning Weight (WW) and Yearling Weight (YW) Since feeder cattle are marketed by the pound, heavier calves will return more $ than lighter weight calves. Weaning and yearling weight EPDs are expressed as the added pounds of weaning and yearling weight of offspring expected, due to genes for growth passed down from sire and dam. Pounds at weaning is most indicative of profit, but looking at YW as well as car- cass traits will aid in selection. Selling high quality calves at weaning that will perform well to yearling age and into the feedlot will help to raise high -value, profitable calves. Milking Ability (MK) A sire’s milk EPD is expressed as the additional pounds of weaning weight of calves (grandprogeny of the sire) from daughters due to genes passed on from milk and mothering ability from the sire to his daughters. Determin- ing the optimum range in milk EPDs which is most appropriate for any given situation and the amount of emphasis that should be given to this trait depends on a number of different factors including environment and management practices. A higher milk EPD in a female would typically indicate higher maintenance (feed) costs. Total Maternal (TM) The TM EPD is reflected as a formula (index), as the Milk EPD + half of the WW EPD. By combining the growth and milk information, this can be used to predict the weaning weight performance from a sire’s daughters. Since this is an index, there is no accuracy reported. A larger TM value indicates a female that returns comparatively higher weaning weights on her calves.
Marbling (MB) MB EPDs are expressed as differences in intramuscular fat in the ribeye.
$TPI Terminal Profit Index, constructed to identify terminal sires that produce the highest profit potential fed cattle. The index is reported in dollars and represents expected differences in profit per mating. $TPI places positive economic weight on post-weaning gain. Dry matter intake is also includ- ed, and combined traits explain differences in feed conversion. The pa- rameters of this index include the most recent 10 years of reported fed cattle and grid pricing, Kansas State University reported feedlot cattle performance, and NALF production data.
Selecting Beef Cattle for High Altitude Conditions Altitude Recommendation Below 5,000 feet PAP not an issue 5,000 to 7,000 feet PAP <50 mm Hg 7,000 to 9,000 feet PAP <45 mm Hg Above 9,000 feet PAP <41 mm Hg Values listed are for animals 18 months of age and older PAP values will typically be 2 mm hg lower when measured at 12 months of age.
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