Beef Cattle Browsing – February 2013

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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.  Media, feel free to use this information as needed and cite Texas A&M University Beef Cattle Browsing Newsletter, Dr. Steve Hammack.

NEW NATIONAL TRACEABILITY RULES

Starting March 11, 2013, all livestock moved interstate must have an approved method of identification and documentation.  Brands, tattoos, and brand registration will be accepted as identification, if accepted by the shipping and receiving State or Tribe, along with numerous other methods.  At this point, cattle under 18 months of age are exempt, unless movement is for show, exhibition, rodeo, or recreational events; rules concerning younger cattle will be addressed later.  Also exempt are cattle going directly to a custom slaughter facility. (http://www.aphis.usda.gov/traceability)

ENVIRONMENTAL AND ECONOMIC EFFECTS OF BEEF PRODUCTION SYSTEMS
Computer simulation was used to estimate greenhouse gas emissions from beef production.  Of total emissions, the cow-calf phase was found to create 69-72% and the feedlot phase 17-27%, with the remainder from the stocker phase.  Five systems of production were evaluated:

  • natural (NT), with and without stockering, using no growth-promoting technologies;
  • implant (IM), with and without stockering, using ionophores and growth implants;
  • and IM+, with stockering, using ionophores, growth implants plus beta agonist.

Inclusion of a stocker phase increased total emissions by about 6%.  For both stocker and no stocker management, IM reduced emissions over NT by about 7% and IM+ by about 9%.  The authors noted that use of technologies during stockering and feeding have no effect on the cow-calf phase, where the majority of emissions occur.

Total cost of production per cwt carcass was about 6% higher without a stocker phase.  (This difference would probably be higher under today’s cost of feeding.)  Cost of production was about 7% higher for NT over IM.  IM+ reduced cost of production compared to IM by about 3%.  The authors found the NT system would require a sale price about 8% higher to equalize net economic return. (J. Animal Sci. 90:4641 and 4656; Univ. of California and USDA-ARS at University Park, PA)

DOES FEEDING GENETICALLY-MODIFIED CORN TO DAMS AND PROGENY AFFECT PROGENCY?
No, at least not unfavorably in one study with swine. Sows were fed either normal or Bt-modified corn during gestation and lactation. Pigs were weaned at approximately 28 days of age and half of each sow group also was fed either normal or Bt-modified corn for 115 days after weaning.

Progeny from sows fed Bt-corn had significantly higher feed intake, ADG, final weights, and carcass weights. Pigs fed Bt-corn had higher feed intake and dressing percentage. Blood chemistry of all groups was at normal levels and no pathology was observed in any organs. The authors concluded that Bt-corn diets were not detrimental to pig growth or health. (J. Animal Sci. published online 10/24/12 before print; authored by members of five Irish research institutions.)

GENETIC ASSOCIATIONS BETWEEN BODY COMPOSITION MEASURED BY ULTRASOUND OR VISUALLY
Data were analyzed on Brazilian Nelore cattle. Depending on the trait, data were available for as many as 5,057 sires and 15,551 dams. Objective data included 120-day weight and 550-day weight and ultrasound for ribeye area, rib fat cover, and rump fat cover. Subjective data included body length and depth, body condition, muscle score, and sheath and navel characteristics.

Because of low genetic relationships found in the study, genetic selection for less sheath/navel should have no effect on body dimensions or composition. Genetic relationships were generally positive between ultrasound and subjective measures. The authors concluded that visual selection for body length and depth should improve body composition, but not as quickly as selection based on ultrasound evaluation of composition. (J. Animal Sci. 90:4223; several Brazilian research institutions and University of California-Davis)

EFFECT  OF  RATE  OF  DEVELOPMENT  ON  HEIFER  PERFORMANCE
Weaned, spring-born, primarily Angus-background heifers initially averaging 546 lb were developed for six months. Heifers were first grazed on stockpiled pasture that had been previously hayed and/or grazed. Grazing was provided at available forage allotment of either 3.5% (LO) or 7.0% (HI) of body weight, followed by both groups being on haylage and soybean hulls.

At the start of breeding, HI heifers averaged 796 lb and LO 759 lb. There were no significant differences for either AI, cleanup, or total pregnancy rates. The authors concluded that development of heifers can be moderately delayed early in development without adverse effects on reproduction. (J. Animal Sci. 90 E-Suppl. 2:332; West Virginia Univ.)

NOTE: This and other recent research indicates that heifers can be developed to first breeding at a slower rate, especially early in the process, and to a lower percentage of expected mature weight than once thought necessary without detriment.

EFFECT  OF  CREEP-FEEDING  ON  PERFORMANCE  AND  CARCASS
Creep-feeding suckling calves generally has been shown to increase weaning weight, but with variable effect on efficiency and economics. Some recent research has shown that elevated pre-weaning nutritional levels can increase carcass marbling after finishing. In this study, calves were creep fed for three months before weaning. A corn-based and a soyhull based ration were used. Treatment groups, maintained at three different locations, were

  • 120 spring-calving Angus cows and calves on bermudagrass pasture, weaned in late September, backgrounded in drylot 45 days before finishing:
    • with corn creep
    • with soyhull creep
    • with no creep
  • 60 fall-calving Brahman-cross cows with Angus-sired calves on ryegrass pasture, weaned in mid May, backgrounded in drylot for 69 days before finishing:
    • with corn creep
    • with soyhull creep
    • with no creep
  • 80 fall-calving Red Angus cows and calves on native range, weaned in late March, backgrounded in drylot 2 weeks, placed on grazeout wheat until mid May followed by native range grazing before finishing:
    • with corn creep
    • with no creep

Creep consumption was targeted at about 1 lb/day; actual varied by groups from 0.8 to 1.3 lb/day, except for the native range group at 1.7 lb/day. Type of creep did not significantly affect consumption amounts, ADG, or efficiency of creep conversion to gain. Though not statistically analyzed, efficiency of conversion was best for spring calving on bermudagrass, intermediate for fall calving on ryegrass, and poorest for spring calving on range. (The authors suggested that the high-starch creep used on native range may have been poorly utilized.) Creeped calves had significantly higher ADG in the bermudagrass and native range groups, but not in the fall calving on ryegrass group.

During backgrounding, performance differed little due to prior creep treatment. There were no significant differences among creep treatments on either feedyard performance or carcass factors, so higher nutrition from creep did not affect carcass quality. The authors concluded that creep feeding increased ADG on lower-quality forage. (Prof. Anim. Sci. 28:507; Univ. of Arkansas, USDA-ARS at Woodward, OK).

NOTE: Based on this and prior research, benefits of higher gain and efficiency from creep feeding often vary on forages of differing quality.

SKIN  TEMPERATURE  VS.  EFFICIENCY
Infrared thermography (IFT) was used to evaluate skin temperature of high-concentrate fed Nelore steers, grouped by Residual Feed Intake (RFI) as either low RFI (more efficient) or high RFI (less efficient). IFT readings were taken on the front of the head, eye, cheek, flank, ribs, rump, and front feet: rectal temperature was also taken. Mean air temperature during the trial was as high 87 degrees F. There was generally little difference in skin temperature between RFI groups, except that front head temperatures were lower for high RFI. However, rectal temperature was lower for low RFI. The authors speculated that the lower rectal temperature at the same skin temperature of low RFI cattle may indicate improved efficiency of thermoregulatory mechanisms, at least in Bos indicus. (J. Animal Sci. 90 E-Suppl. 2:336; Univ. of Sao Paulo, Univ. of Londrina)

WHAT  THE  HECK  IS  THIS  STUFF?
Ingredient labels on food products, including meat, can be long and, to some, scary. Some of the ingredients are just names of foods well known by everybody. But anything with a chemical name can send up a red flag to many consumers. Why all this stuff anyway? The four primary reasons for added ingredients are to maintain or improve freshness, improve taste, provide texture, and improve appearance. Ingredients are regulated by the Food and Drug Administration, which requires that proper scientific terms be used. Many of those terms are nothing more than what is contained in food without added ingredients. Most of us just don’t know the chemical makeup of a food, even if it’s “organic” and right out of our garden. For a list of some common ingredients and what they do see http://foodinsight.org.

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