Beef Cattle Browsing – September 2010

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

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.

That was the theory voiced in a recent report on a national radio program. According to an anthropologist’s theory, primitive humans existed on plants that were high in fiber and low in calories. This required a big gut and lots of dietary energy to digest this material. Then we started eating meat, around 2.3 million years ago. Over time, the diet shifted to more meat when it was available. More energy was available in the diet, less energy was needed for digestion, and so more energy was available for brain growth. Eventually, cooking developed which made meat, and other foods, easier to digest. Just a theory? Maybe, but it’s an appealing one, and it’s been advanced before by other scientists. (National Public Radio broadcast, 8/2/10)

MARC III (1/4 each of Angus, Hereford, Red Poll, Pinzgauer) and Angus females were bred to Angus (AN), Hereford (HE), Beefmaster (BE), Bonsmara (BO), Brangus (BR), or Romosinuano (RO) sires. [Bonsmara contain Africander, Shorthorn, and Hereford. Romosinuano are a Criollo type (non-Bos indicus, largely of Spanish origin) native to Colombia.] Steers (n=621) from two spring-born calf crops were weaned in the fall, grown for three to four months, and finished on a high-concentrate ration.

Results of percent Choice, Yield Grade score, and taste panel tenderness are presented below, adjusted to slaughter endpoints of 14 months of age (i. e., fed for the same length of time) and to 0.4 inches carcass fat thickness:

Percent Choice Yield Grade Tenderness**
Age adj Fat adj Age adj Fat adj Age adj Fat adj
Angus 69 61 3.2 2.8 5.91 6.20
Hereford 52 48 2.9 2.7 5.77 5.89
Beefmaster 32 26 3.1 2.8 5.66 5.87
Bonsmara 39 42 2.4 2.6 5.86 5.76
Brangus 47 47 2.7 2.7 5.72 5.72
Romosinuano 34 43 2.3 2.3 5.79 5.47
LSD* 17 21 0.2 0.2 0.17 0.21

*LSD – Breed differences at or greater than LSD value are significant at 0.05 level
** 1 = extremely tough, 4 = slightly tough, 5 = slightly tender, 8 = extremely tender

Adjusted to the same age, AN had significantly higher percent Choice than the other breeds. Within HE, BR, and BO there was no sig. difference. HE was sig. higher than BE and RO, but BR was not. Adjusted to the same fat thickness, differences tended to diminish but rankings stayed the same.

Adjusted to the same age, RO and BO had sig. higher leanness (numerically lower Yield Grade) than HE and BR which were sig. leaner than AN and BE. Adjusted to the same fat cover, Yield Grade did not sig. differ across all breeds, indicating that muscularity was similar among all breeds.

AN ranked highest on tenderness, especially in the fat-adjusted analysis. The other five breeds differed little, except for RO being lowest when adjusted for fat cover. However, most consumers would probably not be able to distinguish these levels of difference in tenderness among the six breeds.

Overall, AN were highest in meat quality attributes but lowest in yield of red meat. (J. Animal Sci. 88:3070; U. S. Meat Animal Res. Ctr.)

An online poll of over 2500 adults sheds some light on our cooking habits. Over all age groups, four out of five people enjoy cooking and two out of five cook at home at least five times a week. Three out of four sometimes use frozen ingredients and convenience methods such as microwaves and toaster ovens. About the same number of men and women love to cook. Those 65 years of age or older cook more often than those from 46 to 64, but a higher percentage of the latter group enjoys cooking. Younger groups, 34 to 45 and 18 to 33, enjoy cooking as much as older groups but do so less often. (, 7/30/10)

Prior research indicated that Vitamin E supplementation improved conception in beef heifers and reduced postpartum interval and days to conception in dairy cattle. In this study conducted over two years, 152 2- and 3-year-old spring-calving Angus-cross females received hay and corn silage and supplemented as follows:

  • 1000 IU/day of synthetic Vitamin E (SYN)
  • 1000 IU/day of natural-source Vitamin E (NAT)
  • control receiving no Vitamin E (CON).

In a second study, 75 cows were grazed and divided among the same treatments, with Vitamin E provided via a vitamin-mineral mix. In both studies, supplementation began six weeks before calving and continued until the start of breeding. In the first study, blood samples were collected at calving every week beginning four weeks after calving. In the second study, blood samples were collected at breeding and 7 and 14 days before estrus synchronization. Breeding was by AI followed by natural service with clean-up bulls.

In the first study, both SYN and NAT had greater (P<.001) serum concentrations of Vitamin E at calving. There were no differences (P<0.55) in percent cycling before synchronization or time to return to estrus after resuming estrus before synchronization. SYN tended (P=0.09) to have greater first-service conception but overall conception did not differ (P<0.23). In the second study, NAT had greater (P=0.02) serum Vitamin E concentrations at breeding. But there was no effect (P<0.17) of SYN or NAT on length of resumption of estrus or on conception rate, either first-service, first- plus second-service, or overall. In addition, there were some differences in serum Vitamin E concentration of calves nursing supplemented dams but no difference (P<0.05) in calf birth weight, ADG, or weaning weight. The authors concluded that Vitamin E supplementation had no important effects on reproduction or calf performance. (J. Animal 88:3121 and 88:3128; Purdue Univ., ADM Nutrition Research, Univ. of Wyoming)

We sometimes hear that human dietary problems from E. Coli contamination of beef are a result of “factory farmed” cattle fed high-grain rations in feedyards. However, recently there was a recall in Colorado of 66,000 lb of ground meat and tenderized steaks from bison. Bison are not managed in feedyards on high-grain rations. (USDA)

A group of 144 Angus-cross cows was divided into three groups. From 5 ½ months into gestation until a week before estimated date of calving, cows were maintained on either:

  • ad lib grass hay (average disappearance = 27.2 lb), (HY)
  • 11.7 lb shelled corn, 4.6 lb grass hay, 2.2 lb supplement, (CN)
  • 9.0 lb dried distillers grains, 4.6 lb grass hay, 2.2 lb supplement, (DG)

These amounts were calculated to provide the same energy levels across treatments. Every three weeks cows were weighed and Body Condition Scored. After calving, all cows received the same nutrition and management. Milk production was determined by the weigh-suckle-weigh technique at approximately one, three and seven months after calving.

During gestation, DG gained more weight (P<0.04) but there were no differences (P<0.28) in BCS. Calf birth weight was heavier (P<0.001) for DG and CN, but there were no differences (P<0.21) in calving difficulty. Also, there were no differences in conception rates (P<0.79), milk production (P<0.51) or milk composition (P<0.39). Overall, energy source did not affect any production traits except birth weight. The authors concluded the latter indicated some differences in partitioning of energy to the fetus. (J. Animal Sci. 88:2717; Ohio State Univ.)

Comparisons were made of heifers by Angus sires with estimated Residual Feeding Value (RFI) breeding values that were numerically high (low efficiency) or low (high efficiency). After weaning, heifers were developed in a commercial bull testing facility. There were no significant differences (P<0.05) between the two sire groups in feed consumption, gain:feed, or weight gain. The authors indicated that the test ration was lower in energy than that used to test their sires and speculated this may have masked expression of genetic differences in the heifers. This poses a question. What is the relationship between RFI measured in a feedyard and efficiency of brood cows managed on pasture or range? (Prof. Anim. Sci. 26:328; Kansas State Univ.)

July 1 cattle numbers show continued declines. Compared to a year ago, all classes of cattle were down by about one to three percent. The only exceptions were dairy replacement heifers, up 2.5%, and cattle on feed, up 3.4%. (USDA)

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