Different forages affect cattle weight, beef taste

Different forages affect cattle weight, beef taste

THE forages that beef cattle eat affect the nutritional and flavor qualities of the meat, according to a team of Clemson University animal science researchers who reported that steers grazing on one of five forages kept in paddocks showed significant differences in growth, carcass and meat quality.

The research can help cattle producers with alternatives to corn and prepared feed when they are looking to add weight and value to their animals prior to sale, Clemson said.

Researchers John Andrae, Susan Duckett, Steve Ellis, Maggie Miller and Jason Schmidt — supported by the Clemson University Experiment Station, Clemson Extension Service and College of Agriculture, Forestry & Life Sciences — conducted a two-year experiment feeding Angus steers enclosed in five-acre lots planted with alfalfa, bermuda grass, chicory, cowpea or pearl millet. They reported their findings in the Journal of Animal Science.

"Finishing steers on alfalfa and chicory during summer increased steer performance," they wrote.

They also reported that finishing steers on legumes (alfalfa and cowpea) increased carcass quality, and in taste tests, consumers preferred the flavor of the meat. Finishing on bermuda grass and pearl millet improved the levels of healthy fatty acids that may reduce cancer risks.

"The study is useful to beef producers in the Southeast, where summer heat is a challenge for finishing cattle," Clemson forage and pasture specialist Andrae said. "These forages have potential to boost steer growth and quality when traditional cool-season forages are either dormant or have slow growth rates and don't do as good a job finishing cattle for market."

 

U.K. cattle TB, badgers

In the U.K., the cattle industry has been fighting bovine tuberculosis (TB) for a long time, and the role of the Eurasian badger (Meles meles) in spreading bovine TB has been debated intensely as part of discussions about whether badgers should be culled to control the disease.

According to a new white paper by scientists with the Imperial College London, badgers are ultimately responsible for roughly half of TB in cattle in areas with high TB prevalence, based on new estimates drawn from data from a previous badger culling trial.

However, only around 6% of infected cattle catch TB from badgers, with onward transmission between cattle herds accounting for the remainder, the study suggests.

The findings are published in the journal PLOS Currents: Outbreaks.

Britain's "Randomised Badger Culling Trial," which ran from 1998 to 2005, found evidence that culling could reduce TB in herds inside culled areas while increasing TB in nearby areas.

Mathematical models based on data from the trial were previously used to calculate an estimate of the proportion of TB in cattle that could ultimately be attributed to transmission from badgers.

The new paper provides a more detailed analysis. It estimates that badgers ultimately account for 52% of cattle TB in areas where prevalence in cattle is high. There is considerable uncertainty around this estimate, but the researchers said 38% is a robust minimum value for the estimate. There is no robust maximum value.

"These findings confirm that badgers do play a large role in the spread of bovine TB. These figures should inform the debate, even if they don't point to a single way forward," said professor Christl Donnelly from the Medical Research Council Centre for Outbreak Analysis & Modeling at the Imperial College London.

The mathematical model suggested that 5.7% of transmission to cattle herds is from badgers to cattle, with the rest of the contribution from badgers resulting from onward transmission among cattle herds.

 

Fat, marbling

On a carcass, subcutaneous fat is external fat, or back fat. Marbling is the intramuscular fat — the white flecks within meat that carry much of the flavor and determine taste.

Robert Maddock, a meat scientist at North Dakota State University, recently authored a white paper, "The Relationship between Subcutaneous Fat & Marbling," to help sort out the finer points of judging the marbling on live cattle.

It's a key issue in cattle feeding because putting on too much back fat means "lower carcass yields and higher costs of gain, whereas lack of marbling results in lower carcass value and generally lower consumer eating satisfaction," Maddock said.

The crux of the matter is that these two manifestations of fat are only moderately related, at best. Estimating fat cover is "not a good method of evaluating the marbling potential of finished cattle," he said.

Still, it is possible to manage both or even enhance marbling while keeping back fat in check.

U.S. Department of Agriculture quality grades declined for 16 years from 1990 to 2006, and the incidence of over-finished, yield Grade (YG) 4 cattle increased for the last half of that period, according to an announcement from Certified Angus Beef. Since 2006, both quality and YG have improved.

Only a tiny fraction of Prime carcasses were YG 1 in the 2011 "National Beef Quality Audit" — the same tiny fraction of Standard (no-roll) carcasses that were YG 5. Most Prime and top Choice carcasses were YG 3.

Marbling growth is linear and "occurs at a relatively constant rate throughout finishing," the paper notes. "The high caloric intake of cattle in the feedlot allows the body to deposit marbling at the same time as it deposits subcutaneous fat."

That can start before cattle enter the feedlot, however, and the white paper points out:

* As long as the caloric and nutritional needs of growing cattle are met, energy in excess of requirements for growth will result in marbling development no matter the age of the cattle.

* When calories in excess of growth requirements are available, marbling will develop to the genetic potential of the cattle.

At some point, back fat and YG begin to increase faster than marbling growth. Data from the American Angus Assn. shows that the greatest marbling growth occurs while 12th-rib back fat is increasing from 0.3 to 0.5 in., with little added marbling after 0.6 in.

Tying in economic concerns, Maddock said, "Cattle should be fed until a point where excessive external fat and carcass weight result in discounts greater than any premium that can be obtained from higher marbling scores."

More details can be found in the white paper at www.cabpartners.com/news/research.php.

 

Dairy beef

The University of Minnesota recently completed a feed efficiency trial comparing Wulf Cattle Limousin-Jersey (BEEF BUILDERS) to Jersey steers. The feedlot performance comparison was a joint feed trial conducted with Wulf Cattle of Morris, Minn., as a component of the "Breeding To Feeding" dairy beef program.

The steers were fed at the University of Minnesota's Rosemont facility. Management and feeding of all steers was the same from birth through trial completion, with one exception: zilpaterol hydrochloride was fed to two groups 30 days pre-harvest.

The Limousin x Jersey (LxJ) steers that were not fed zilpaterol had improved feed:gain, average daily gain, heavier hot carcass weights and larger rib-eyes (Table), the Wulf Cattle announcement said. The steers fed zilpaterol performed slightly better in the feedlot. However, the zilpaterol-fed steers' quality grades declined, resulting in more grading USDA Select.

In conclusion, the study indicated that genetic influence had a greater effect than zilpaterol.

 

Effect of zilpaterol and dairy beef genetics on feedlot performance

 

-No zilpaterol-

-Zilpaterol-

 

Jersey

LxJ

Jersey

LxJ

Starting weight, lb.

945

1,180

1,032

1,124

Average daily gain, lb./head

1.21

2.73

1.53

3.24

Gain:feed

14.88

8.5

13.78

7.64

Harvest weight, lb.

1,056

1,443

1,167

1,422

Hot carcass weight, lb.

680

909

736

896

Rib-eye area, sq. in.

11.37

13.87

12.36

15.74

Marbling

494

600

497

470

Quality grades, %

 

 

 

 

Prime

0

8

10

0

Choice

88

92

70

64

Select

13

0

20

36

 

Volume:85 Issue:43

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