Beef Cattle Browsing – February 2004

Beef Cattle Browsing

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

February 2004

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.

Selecting breeding stock on increased yearling weight will increase weight in future generations. However, heavier yearling weight usually results in heavier birth weight, with possible increase in calving difficulty, and heavier cow weight, requiring more nutritional maintenance cost. It has been proposed that the antagonism between birth and yearling weight might be countered by simultaneously selecting for heavier yearling weight and lighter birth weight. USDA researchers in Montana used a composite herd composed of 1/2 Red Angus, 1/4 Charolais, 1/4 Tarentaise genetics. A closed genetic line used sires selected on an index of 365-day weight minus 3.2 times birth weight, and compared it to a closed control line. After 11 years, comparing select to control: 1) birth weight slightly increased; 2) there was approximately 40 lb genetic increase in yearling weight; and 3) weaning weight increased by about half as much as yearling weight. However, cow weight increased almost as much as yearling weight. Selection on the index successfully increased yearling weight with only small increases in birth weight, but cow weight also increased. (J. Animal Sci. 81:2425)

Texas Tech researchers used 2748 Bos indicus influence steers of known background in three treatment groups: 1) control; 2) Synovex-S followed by Synovex-S; and 3) Synovex-S followed by Revalor-S. Steaks were aged for 3, 7, 14, or 21 days. Steaks were evaluated by Warner-Bratzler shear force (mechanical tenderness), trained taste panel, and untrained consumers in six large U. S. cities. The only significant implant effect was that both treatments reduced tenderness as evaluated by the trained panel. Overall, tenderness and flavor improved with increased time of aging. Consumer evaluations were analyzed by level of education and family income. Neither of these factors affected overall steak acceptability or tenderness acceptability. However, consumers with postgraduate degrees recorded lower scores for overall quality, flavor, juiciness, and tenderness than did all other education levels. (J. Animal Sci. 81:3055)

Researchers at the University of Kentucky and University of Florida have reviewed studies of Bos indicus X Bos taurus crossbred cows in the southeastern and Gulf Coast regions of the United States. A primary advantage of B. indicus cross in these areas is adaptability to hot, humid conditions. In addition, they are less likely to be affected by and culled because of calving difficulty, external parasites, internal parasites, pink eye or cancer eye, teeth problems, and some nutritional disorders. Consequently, these females average longer productive lives. The researchers did note that cows of this type may experience more udder problems and prolapses of the vagina/uterus. (Prof. Anim Sci. 19(5):329)

Optaflexx™ (ractopamine hydrochloride), a beta agonist, was approved in June, 2003, to increase live weight gain, improve feed efficiency, and increase red meat yield without affecting beef palatability. Approval has recently been granted by the FDA to allow Optaflexx to be used in conjunction with two other Elanco products, Rumensin® and Tylan® which collectively improve feed efficiency, control coccidiosis, and reduce liver abscesses. Optaflexx is to be fed in confinement for slaughter during the last 28 to 42 days on feed. (Elanco News)

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