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This newsletter is published by Texas AgriLife Extension – Animal Science. Media, feel free to use this information as needed and cite Texas A&M University Beef Cattle Browsing Newsletter, Dr. Steve Hammack.

Editor: Dr. Stephen Hammack, Professor & Extension Beef Cattle Specialist Emeritus

U.S. BEEF EXPORTS
According to the most recent USDA report, the U.S. ranked first among all countries in dollar value of beef exports. Volume of U.S. exports increased 15% over last year. Exports equaled 14% of total U.S. production with a value of almost $200 per head of fed cattle. Top export countries were Mexico followed by Canada, with increases over last year to Japan, Korea, and Hong Kong. (Texas Cattle Feeders Assoc., 8/19)

INFLUENCE OF CARCASS QUALITY GRADE ON PALATABILITY
Studies were made on 1737 genetically-related Angus cattle. USDA carcass grades were Select, Low Choice, Top Choice (upper 2/3, the minimum requirement for Certified Angus Beef®), and Prime. Carcass grade significantly influenced some palatability attributes. The four grades differed significantly from each other in both mechanical and taste-panel tenderness, with Select being less tender and Prime more tender even though connective tissue increased as grade increased from Select to Prime. Beef flavor differed little. While some statistically significant differences were found, the range in values was rather small. For instance, taste-panel tenderness (where 1 = extremely tough to 8= extremely tender) ranged from 5.56 for Select to 6.07 for Prime. However, the authors concluded that “USDA quality grade is still one of the most valuable tools available to predict beef palatability”. (J. Animal Sci. 89:2849; Oklahoma St. Univ., Iowa St. Univ.)

EFFECT OF DAYS OF PRECONDITIONING ON PERFORMANCE
Several research studies have shown greater benefit from preconditioning for approximately 45 days as opposed to 30 days or less. A total of 130 steer calves averaging 616 lb were weaned in mid-September of two successive years and preconditioned for an average of 36 days. Preconditioning was done in 2 acre paddocks of mixed bermudagrass-bahiagrass-carpetgrass with 25-30 steers per paddock. Bermudagrass hay was offered free-choice. Calves also received in troughs 1-2% bodyweight daily of a 14% ration. After preconditioning, calves were fed in a commercial feedyard to average slaughter weight of 1324 lb. Calves preconditioned for 37 to 42 days averaged higher slaughter weight, greater fat cover, and numerically higher USDA Yield Grade (lower leanness) than calves preconditioned for 30 to 36 days. An economic analysis was not included. (J. Animal Sci. 89 E-Suppl. 1:523; McNeese St. Univ.)

GENOMIC TESTING – WHERE IS THE VALUE?
Genomic (DNA) tools are becoming more important in genetic evaluation of breeding stock. Genomic panels have been developed for a number of reproduction, growth, efficiency, and carcass traits. How should these panels be used? Panels are particularly useful for traits that are low in heritability, hard or expensive to measure, measured late in life, or sex specific. According to the consensus of experts in this field, the best use of panels is to incorporate them into EPDs as “genomic-enhanced” EPDs, not as stand-alone tools. The value of these enhanced panels lies primarily in better accuracy of prediction, rather than any change in numerical value of an EPD. The following chart shows EPD change, accuracy increase (from 0.05 with pedigree information only), and number of progeny records that would be needed to equal information from the genomic panel:

Except perhaps for birth weight, the genomic panel provides more improvement in accuracy than a female would provide through her progeny in an entire lifetime of production. Currently, the American Angus Association provides genomic-enhanced EPD. Other breed associations are expected to do so in the near future. As always, regardless of the tool(s) used for genetic selection, producers should emphasize traits important to the production efficiency and financial well being of their operation. (Data from Pfizer Cattle News)

RESIDUAL FEED INTAKE VS. BEEF CHARACTERISTICS
Residual feed intake (RFI) is a measure of efficiency. High RFI animals eat more than predicted, so they are less efficient. Angus steers (n=133) by High, Medium, and Low RFI sires were fed, carcasses evaluated, and palatability measured. There was no significant difference in sire groups in ADG, slaughter weight, fat thickness, carcass weight, Yield Grade, Quality Grade or palatability traits. Carcasses from the High RFI steers had higher (P<0.01) marbling than Low RFI steers. As expected, steers from Low RFI sires consumed less feed and had higher gain to feed ratio. The authors concluded that selection for RFI should have no effect on production or final palatability, but marbling could be affected. (Prof. Anim. Sci. 27:109; Colorado St. Univ.)

EFFECT OF GLUCOGENIC PRECURSORS ON REPRODUCTION
A study was designed to determine if supplemental calcium propionate, a glucogenic precursor (something involved in generating glucose), would affect reproduction. Over three years, primarily Angus, 2- and 3-year-old cows were maintained on central New Mexico native range. Starting two months before calving, all cows were fed 3.6 lb of 36% CP supplement once per week. Cows were fed beginning 7 days after calving for 75 to 120 days (depending on the year) one of the following 36% CP supplements @ 2 lb/day twice per week:

• 12% ruminally undegradable protein, 0% Ca propionate, 5 % glucogenic potential
• 17% ruminally undegradable protein, 4% Ca propionate, 10% glucogenic potential
• 17% ruminally undegradable protein, 8% Ca propionate, 14% glucogenic potential

There was no significant difference in days to first estrus, pregnancy rate, calving interval, cow body weight, cow BCS, milk production, calf weaning weight, or weaning weight per cow exposed. The 10% glucogenic potential did produce higher financial margins per cow. The authors concluded that blood analyses indicated more efficient energy metabolism and better use of forage energy from glucogenic precursors. (J. Animal Sci. 89:2932; New Mexico St. Univ., West Texas A&M Univ., USDA-ARS, Miles City, MT)

FSIS REJECTS IRRADIATION PROPOSAL
Irradiation has been proven to be an effective and low-cost method of protecting consumers from bacteria in meat. However, there has been some resistance to this process because of unfounded health concerns. The American Meat Institute had proposed to the Federal Food Safety and Inspection Service that irradiation be classed as a processing aid that would not require labeling a product as being irradiated. However, FSIS has rejected that proposal. Note: some materials used in processing food, such as some spices, are routinely irradiated without being so labeled. (American Meat Institute Foundation)