Beef Cattle Browsing – August 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




All areas of Texas are experiencing drought, much of it exceptional which is the most severe classification according to USDA. In many areas, cattle producers are selling herds because there is simply no water available. We don’t often hear it stated, but water is a nutrient just as energy, protein, minerals, and vitamins are nutrients.

In extensive grazing areas, multiple water sources may be present. However, cattle may become accustomed to watering from one source. If that source depletes, or becomes unpalatable, water deprivation may occur even if there are other sources available. Also, cattle must be familiar with water locations, so newly-introduced animals should be guided to water and observed to see if they drink.

Water intoxication can occur when cattle drink excessively. This typically occurs when cattle become dehydrated after a period of deprivation. Caution should be exercised when introducing dehydrated animals to water.

Even if supplies are adequate, water quality can affect palatability and consumption. Also, some constituents of water can lead to unthriftiness when present in elevated amounts. Under hot, sunny conditions, stagnant water may lead to development of blue-green algae which can be toxic to cattle. When forage starts to run short, growth of toxic plants around ponds may continue and cattle may consume such plants with detrimental effects. (For more information on water quality see

(Summarized from information provided by Dr. Ted McCollum, Prof. and Ext. Beef Cattle Specialist, Texas AgriLife Center-Amarillo)

Heifers of the Bonsmara breed (containing approximately 5/8 Africander, 3/16 each Hereford and Shorthorn) were developed postweaning on a medium-quality chopped hay diet. Individual hay consumption was measured and animals were weighed every 7 days. Residual Feed Intake (RFI) was calculated. (Low RFI individuals eat less than predicted based on their body requirements and are therefore more efficient.) The highest and lowest RFI heifers were retained for breeding and the same data were collected subsequently as cows.

Low RFI averaged 19.8 lb/day dry matter intake; High RFI averaged 25.5 lb. Frequency of bunk visits did not differ but Low RFI spent less time at the feed bunk. No differences were seen in weight or Body Condition Score. Based on this study, findings of other studies on RFI in growing/finishing cattle appear to apply to developing heifers and producing cows. (J. Anim. Sci. 89, E-Supple. 1:416; Texas A&M Univ.)

Zilmax, fed for short periods before slaughter, has been shown to increase carcass and red meat yields. A study was conducted to assess any possible effect on retail yield. Beef and calf-fed Holstein steers were divided into control groups and groups fed Zilmax for 20 days before slaughter. The following boned, closely-trimmed subprimal cuts were fabricated into retail cuts: chuck roll, shoulder clod, sirloin tip, top round, outside round, eye of round, strip loin, top sirloin, and tenderloin. Statistically significant but slight (approximately 1%) increase in salable yield occurred only in chuck rolls and top rounds from Holsteins. Overall, Zilmax resulted in heavier subprimals and increased number of retail cuts. However, there was no difference in salable yield on a percentage basis. The advantage of Zilmax lies in greater yield going from carcass to subprimal, not from subprimal to retail. (J. Animal Sci. 89:2867; Texas A&M Univ., California Poly. St. Univ., West Texas A&M Univ., Intervet/Schering Plough)

Health and general management 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:

  • about one-half of operations consulted a veterinarian during the previous 12 months; managers of large herds (>200 head) were more likely to consult a veterinarian than managers of small herds (< 50 head)
  • less than one-sixth of producers had never heard of foot and mouth, brucellosis, BSE, anthrax, and BVD; more than one-third had never heard of rinderpest, VS, anaplasmosis, Johne’s, and bluetongue
  • about one-third of producers had brought cattle or calves onto their operations during the previous 12 months, with about half of those being weaned steers
  • about one-third of producers quarantined animals brought in from outside
  • about one-half of operations had no set breeding season, more small operations had no set season
  • over 90% of operations observed females regularly during calving; 95% of females required no assistance at calving
  • almost 60% of calves nationwide were born from February to April.


For some time, it has been generally recommended that heifers be developed to 65% of predicted mature weight before breeding. This may require significant levels of supplementation or, in some areas, management in drylot on corn silage or other high-quality harvested forage. Recent research has indicated that development to only 55% of mature weight may be adequate, which can often be done with less supplementation or lower-quality forage. A study was conducted to evaluate two systems employing relatively low rates of development and cost.

In two studies at two locations, heifers were developed on winter range (WR) or corn residue (CR). About one month after weaning, beginning in mid-November, both groups were grazed until mid-February; during that time all heifers received 1 lb/day (at one location) or 2 lb/day (at the other location) of a 30% CP supplement. After these treatment periods, heifers were grazed together on WR (supplemented with 1 lb/day of 30% supplement) for about 100 days.

At one location, CR heifers tended to gain less before breeding; this was not true at the other location. There were no significant differences between WR and CR in prebreeding weight, percentage of predicted mature weight, weight at pregnancy determination, percent puberty, AI conception, AI pregnancy rate, final pregnancy rate, precalving weight, percent of calves born in first 21 days, calf birth date, calf birth weight, dystocia score, cow weight at weaning, calf weaning weight, or 2nd-season pregnancy rate. Also, net cost of developing a pregnant heifer did not significantly differ. Either of these development systems resulted in similar and adequate performance and similar economics. (J. Animal Sci. 89:2365; Univ. of Nebraska)

Predominantly Angus cows at two locations were evaluated for any effect of temperature and barometric pressure on calving incidence. Cows calved in spring (Jan-Apr) or fall (Sep-Dec). For spring-calving cows, barometric pressure was higher and temperature was lower on date of calving and the three days before calving. For fall calving cows, temperature was higher at and before calving, but there was no effect due to pressure. The authors suggested monitoring weather conditions as a possible indication of calving. (J. Animal Sci. 89, E-Supple. 1:418; Univ. of Arkansas)

The Beef Reproduction Task Force consists of Extension Specialists from nine land-grant universities. The Task Force has developed online resource material addressing topics such as an estrus synchronization planner, recommended synchronization protocols for heifers and cows, heat detection, understanding the estrus cycle, and others. These are available at

Data were reported on almost 200,000 calves weighing from 500-600 lb sold on video auctions last year from June to September for fall delivery. Compared to purebred Angus, average discounts were: black-hided calves = $1/cwt, Continental-influenced and non-Angus British = $3-4/cwt, Brahman-influenced = $6/cwt. Vaccination and weaning programs added $2-10/cwt, depending on the program. Calves sold under certified programs bring more than those under generic programs. Over the last five years, age- and source-verified calves brought premiums of $1.25-2.50, which are directly tied to some export market standards dealing with maximum age. Calves managed for natural or non-hormone programs bring from $0-2/cwt more. The majority of calves with value-added management sold on video auctions come from the Northern and Southern Plains. (

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