Beef Cattle Browsing – December 2013

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

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

Beef Cattle Browsing is an electronic newsletter published by Texas A&M AgriLife Extension, Department of Animal Science at Texas A&M University. This newsletter is a free service and is available to anyone interested in beef cattle.

On December 11, the U. S. Food and Drug Administration proposed plans concerning “antimicrobial drugs that are considered medically important and which are approved for use in feed and water of food animals”. Under this plan, the FDA asks “animal pharmaceutical companies to revise the FDA-approved use and conditions on the labels of these products to remove production indications”. The plan also would “change the current over-the-counter (OTC) status to bring the remaining appropriate therapeutic uses under veterinary oversight”.  In short, antimicrobial drugs that are considered important in human medicine would no longer be permitted in feed or water for production purposes (improved weight gain, efficiency, etc.) and those same antimicrobial drugs used in feed to water to treat, control, or prevent sickness in food animals would require veterinary approval. To view the FDA announcement see:

A 112-day performance test (on a ration of 53% corn, 39% alfalfa silage) was conducted over six years on 328 crossbred bulls. ADG, and RFI were calculated. Two RFI values were calculated, one of which included an adjustment for differences in mid-test ultrasound rib-fat thickness. At the conclusion of the tests (at average age of 417 days) 110 bulls were selected for breeding. On these bulls, scrotal circumference (SC) was measured and samples taken to evaluate sperm motility and viability.

As has been found in some other research, high RFI (low efficiency) bulls were also significantly less efficient measured as gain:feed, consumed more feed, and were not different in ADG than low RFI bulls. When halved into two groups of 55 high RFI and 55 low RFI bulls, there was no significant difference in SC, sperm motility, or sperm viability. The authors then compared the 10 bulls lowest in RFI (which might be done if exercising extreme genetic selection for that trait) and the 10 highest RFI bulls. The 10 bulls with highest RFI values were significantly highest in sperm motility and viability. Also, when RFI included adjustment for ultrasound fat, the 10 high-RFI bulls were significantly higher in SC. The authors concluded that young bulls with highest efficiency may have decreased fertility traits “which is an undesirable effect of selection for improved efficiency that needs to be addressed through multiple-trait selection”. That is, as is generally true for all traits, single-trait genetic selection should be avoided.

(Can. J. Anim. Sci. 93:185; Univ. of Guelph, Univ. of Saskatchewan, No. Dak, St. Univ.)

Consumers are confronted with a sometimes bewildering array of labels on food, often with similar wording. To a typical consumer, is there any distinction between the USDA-approved terms of “natural” and “naturally raised”? Probably not. But the first term deals only with how a product is processed, if at all, and the second deals with how an animal is produced. How about “grassfed” and “grass finished”? The USDA has a definition for grassfed and so does the American Grassfed Association, which is much more detailed and restrictive. There is no specific definition for grass finished.

A current publication lists 84 terms shown on labels. Of those, 48 have no legal or regulated definition and 8 have independent third-party certification. Some terms would be familiar to anybody raising cattle, such as those dealing with USDA quality grade. Many deal with animal welfare or environmental topics and others address things perceived by some to affect health, other than official inspection for safety and wholesomeness. The list is available at

A recent article in the popular press indicated it’s 1350 lb.  How was that determined? By working back from an “ideal” carcass weight. A large cattle feeding company said 850 lb carcasses have the largest potential profit. Assuming typical dressing percent, that equates to a live slaughter weight of about 1350 lb. In general, slaughter weight of steers at 1/2 inch fat cover is thought to be about the same weight as that of the cow used to produce that steer, if the sire and dam are genetically equivalent.

What if 1350 lb cows are too large for the production conditions? Maybe 1200 lb cows fit best. If their steers are fed to 1350 lb they will probably be less efficient and fatter than desired. But, if fed to 1200 lb those steers efficiency and fatness should be about the same as the 1350 lb steer out of the 1350 lb cow. The 1200 lb steer should yield a carcass of about 750 lb, certainly acceptable and even preferred for some uses. In short, for the cow/calf producer, even one retaining ownership through carcass grid marketing, there are more things that should determine optimum cow size than the desires of a feeder.

Proper use of animal health products is essential in order to obtain maximum benefit. A study was conducted of 129 producers’ and 47 retailers’ refrigerators used to store products. Temperatures were recorded every 10 minutes for at least 48 hours; 31% of producers’ and 34% of retailers’ refrigerators maintained recommended temperatures in the recommended range of 2° to 7° C.  >95% of the time. But 33% of producers’ and 17% of retailers’ refrigerators were in the correct temperature range <5% of the time. These results were similar to some other studies, but showed slightly lower compliance with temperature recommendations.

Among producers:

  • 94% gave injections in the neck
  • 88% mixed modified-live vaccines only as needed and protected them from sunlight
  • 94% kept vaccines in a cooler
  • 88% read and followed labels
  • 72% kept vaccination records at least one year
  • 72% disassembled syringes to clean
  • 64% cleaned syringes with hot water only
  • 46% changed needles at least every 20 animals
  • 44% changed needles as needed

Among retailers:

  • 67% trained employees to answer questions regarding products
  • 66% offered customers ice packs
  • 60% trained employees to handle products
  • 49% provided product information
  • 44% monitored refrigerator temperature with a thermometer but 41% did not
  • 40% provided ice to purchasers routinely
  • 29% provided ice and a Styrofoam cooler
  • 26 % said ice and product information was the producers’ responsibility

(Prof. Anim. Sci. 29:313; Univ. of Idaho)

According to a USDA study, 96% of finishing cattle receive a growth implant at least once. Five studies, totaling 6552 steers, were conducted in five commercial feedyards in five states. Yard-average initial weights ranged from 700-836 lb and days on feed was 138-200. Treatments in all five yards were;

  • initial implant of 14 mg estradiol and 100 mg TBA, followed on day 52 to 92 by implant of 28 mg estradiol and 200 mg TBA
  • initial implant of 200-day slow-release 40 mg estradiol and 200 mg TBA.

In four of the five studies, final weight, total weight gain, ADG, and carcass weight were higher for the two-implant treatment; feed efficiency was higher in all five studies for two implants. In four of the five studies, percent Choice and Prime was higher for the single implant; in three studies percent Yield Grade 1 and 2 was lower for the single implant. As has generally been found in other research, more aggressive implants result in better performance and carcass leanness but lower carcass quality. Choice of an implant program depends on how those variables balance for a particular situation, and how cattle are marketed.

(Prof. Anim. Sci. 29:219; Pfizer Anim. Health, Larson Nutrition Service, Univ. of Minnesota, Cactus Research, Innovative Livestock Services, Summit Research.)

A study was conducted over two years, using 120 mature Angus X Hereford cows. Cows were managed to start the last trimester of pregnancy at different target Body Condition Score. All cows were provided 28 lb of 6.4% CP meadow hay. Half of the cows also received 14 lb weekly (fed three time a week) of 31% CP dried distillers grains with solubles (DDGS). After calving in March, cows were managed together.

Results for cows were:

Trait/Group Low BCS High BCS No Supplement Supplement
Initial wt. 1107 * 1243 1177 1173
Calving wt. 1129 * 1219 1135 * 1210
Weaning wt. 1140 * 1203 1162 1181
Initial BCS 4.4 * 5.7 5.1 5.0
Calving BCS 4.4 * 5.3 4.8 * 5.0
Weaning BCS 4.7 * 5.2 4.9 5.0
Pregnancy % 79.3 * 91.6 85.2 85.6

*=Significantly different within type of treatment

Of calves born, calves from the high BCS cows were significantly higher in percent live calves at birth (100% vs. 90%) and at weaning (99% vs. 88%); and birth weight (91 lb vs. 85 lb). The only calf trait that differed significantly for the supplementation treatment was that calves from cows supplemented during late pregnancy were 18 lb heavier at weaning. There were no significant differences in growing after weaning, finishing, or carcass. As most other studies have shown, maintaining cows in adequate body condition positively affects cow performance and profit, if it can be done economically. Supplementation can be of benefit, depending on the conditions, but is not always.

(J. Animal Sci. 91:5485; Oregon St. Univ., Univ. of Nebraska)

Methane gas released by cattle has received attention in recent years because of potential negative atmospheric effects. Researchers wondered if cattle that are more efficient in using feed might emit less methane. In two experiments, efficiency was measured as gain:feed and as Residual Feed Intake. In the steer study, regardless of the measure, efficiency had almost no relationship to methane production. In the heifer study, RFI was not significantly related to methane production, but as gain:feed increased so did methane production. The authors therefore concluded that cattle that are inherently more efficient do not produce less methane and, in some instances, may produce more.

(J. Animal Sci. 91:4826; U. S. Meat Anim. Res. Ctr.)

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