Beef Cattle Browsing – July 2011

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




The 57th Annual Beef Cattle Short Course will be held on the campus of Texas A&M University on August 1-3, 2011. For information on the schedule, registration, etc. go to

Due to lack of funding, effective August 1, 2011 the Texas Animal Health Commission will discontinue testing for brucellosis at livestock markets. In addition, TAHC will not enforce the requirement that test-eligible cattle changing hands be tested. Texas has been officially brucellosis-free since February 1, 2008. Cessation of testing will not affect the state’s official brucellosis-free status. (TAHC news release, 6/17/11)

A recent summary of studies on behavior found that objective measurements of temperament alone are more useful than subjective measures alone; combinations of the two are the most useful. The summary indicated that excitable cattle:

  • need longer periods of time to adapt to human interactions;
  • are more likely to injure themselves and people and to damage equipment;
  • have elevated levels of stress hormones which negatively affects response to vaccination and immune challenges;
  • have higher medical treatment costs;
  • have lower ADG, carcass weight, and carcass quality.

Since temperament has been found to be moderately heritable, the authors indicated that genetic selection for improved temperament should be possible. (Proc. 2011 Beef Improvement Federation Annual Meeting, p. 78)

A study was conducted in the Upper Gulf Coast region over three years, using January- to April-calving Brangus cows, incorporating four grazing systems on primarily common bermudagrass/Dallisgrass pasture as follows:

  • continuous grazing, low stocking (CL, 0.5 cows/acre);
  • continuous grazing, medium stocking (CM, 0.8 cows/acre);
  • continuous grazing, high stocking (CH, 1.1 cows/acre);
  • rotational grazing in 8 paddocks, high stocking (RH, 1.1 cows/acre).

Forage mass did not differ early in the grazing period (February-April) but was higher for CL later (May-October). Among the three continuous systems there was little difference in quality of diet selected, as measured by simulated bite samples. However, in comparing the two high-stocked systems, crude protein selected was higher and fiber content lower for CH than RH.

There was little difference in cow weight change or calf ADG from February through April. From May through June, cows lost more weight and calves gained less as stocking rate increased; RH cows lost more weight than CH. From July through October, CL and CM cows increased in weight while CH and RH changed little; CL and CM calves gained more than CH and RH.

Labor required was higher for RH, intermediate for CM and CH, and lowest for CL. Revenue was highest for CH and RH, intermediate for CM, and lowest for CL. Total expenses from lowest to highest were in the order of CL, CM, CH, RH. Returns per acre over total expenses were: CL $8.35; CM $71.22; CH $62.56; RH – $26.06. The authors noted that results from rotational grazing might be different under lower stocking rates and on different types of forage. (Louisiana St. Univ. Ag Center Beef & Forage Reports)

Zilmax (Zilpaterol hydrochloride) fed to finishing steers and heifers for 20-40 days before slaughter has been shown to increase weight gain, increase muscling, and improve USDA Yield Grade. A study was conducted to determine effects of Zilmax fed to cull cows. A total of 320 2- to 10-year-old cows were fed from 75 to 110 days. Beginning 24 days before slaughter, half of the cows were fed Zilmax until the withdrawal period 4 days before slaughter. Over the last 24 days ADG and gain:feed were significantly higher in the Zilmax group. Zilmax-fed cows had significantly higher slaughter weight, carcass weight, dressing %, ribeye area, and significantly lower marbling score. Total saleable yield was $879.50 for Zilmax-fed cows and $803.70 for controls. Based on this study, Zilmax has positive effects on performance, carcass yield and muscling, and profit for cows as well as for fed steers and heifers. (J. Animal Sci. 89:2170; West Texas A&M Univ., Intervet)

Record-keeping and individual identification practices were factors surveyed in 2007-08 by the USDA National Animal Health Monitoring System. The survey reached operations in the 24 states comprising 80% of US beef cow operations with 88% of the nation’s cows. Some of the findings were as follows:

  • 83 % of operations (90% of those with >100 cows) kept some form of records;
  • 66% of operations (totaling 79% of the cows) used some form of ID;
  • 50% of operations (58% of the cows) used plastic ear tags;
  • 12% of operations (20% of the cows) used hot brands;
  • 8% of the operations (8% of the cows) used ear tattoos;
  • 5% of the operations (10% of the cows) used ear notches;
  • 2% of the operations (4% of the cows) used freeze brands.


Red Angus Association of America records were analyzed on 8,915 sires. The dataset included approximately 73,000 for intramuscular fat (IMF), 43,000 for scrotal circumference (SC), 38,000 for heifer pregnancy (HP), and 15,000 for marbling score (MS). There were wide variations in these traits, as is true of all breeds. IMF ranged from 0.77% to 10.05% (avg = 3.79); SC ranged from 20 cm to 48 cm (avg = 35.2); HP ranged from 0% to 100% (avg = 80); MS ranged from Devoid to Extremely Abundant (avg = Small42.

Heritabilities were: IMF 0.29; SC 0.32; HP 0.17; and MS 0.35. Genetic correlations were:

  • MS and IMF = 0.80
  • MS and HP = 0.10
  • MS and SC = 0.01
  • IMF and HP = 0.13
  • IMF and SC = 0.05
  • HP and SC = 0.05

The authors concluded that genetic selection for both carcass quality and fertility should not be antagonistic. However, though scrotal circumference in males has been shown to be related to earlier puberty in female relatives that may not translate to higher realized fertility, based on the extremely low genetic correlation in this study between scrotal circumference and heifer pregnancy. (J. Animal Sci. 89:2068; Colorado St. Univ.)

Yes, according to a recent report by Certified Angus Beef. In 1995, 33% of slaughter cattle were majority black-hided. By 2010, this had increased to 64%. Some breeds that originally had few if any black individuals are now majority black in color. It appears that, along with other factors, the advent of various branded-beef programs based on color, especially CAB, has changed the looks of the nation’s cattle herd.

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