Beef Cattle Browsing – August 2013


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

A recent study examined 17 human and 223 nutrient/contaminant research reports comparing organic and conventional food. In the three studies on humans where clinical symptoms were evaluated, there was no difference between organic and conventional sources in occurrence of symptoms such as wheezing and eczema. Two of the 17 studies showed lower urinary pesticide levels in children consuming organic diets, but no difference of clinical significance in pesticide levels in serum, urine, breast milk, or semen. Nutrient levels did not differ, except that phosphorous was statistically higher, but not clinically significant, in organic sources. Pesticide levels were statistically lower in organics, but differences were small and not at levels considered to be risky to health. E. coli levels did not differ. There was a slightly higher occurrence of antibiotic-resistant bacteria in conventional samples. The authors concluded that organic food is not more nutritious than conventional, but organics may slightly reduce exposure to pesticides and resistant bacteria.

(Annals of Internal Medicine 157:348; Stanford Univ.)

A group of 228 mature Angus-cross cows was fed one of three diets for approximately four months before calving: high-fiber grass hay (HY), corn (CN), or dried corn distillers grains (DG). CN and DG were limit-fed at levels to equal total energy consumption of HY. After calving, cows were managed together on the same diet. After weaning, calves were backgrounded on stockpiled pasture for one month, placed on a finishing ration, and slaughtered weekly when individuals reached approximately 0.5 inch fat cover.

Birth weight of HY calves averaged significantly lighter (6.3 lb) than the average of CN and DG, which did not significantly differ. Though not measured in this study, this might or might not result in greater calving ease from HY.  A significant difference in weight between HY and CN was maintained to weaning at 185 days of age (19.4 lb) but not between HY and DG (4.0 lb). There was no significant difference among the three diets in ribeye area or fat cover of calves at weaning, or sickness from birth to weaning or from weaning to slaughter.

There were no significant differences in finishing daily feed consumption, feed efficiency, ADG, slaughter weight, carcass weight, fat cover, ribeye area, or USDA Yield Grade. HY were on feed longer to reach targeted fat cover.  HY dressed significantly higher (1.0%) than DG, with CN intermediate. HY had significantly higher (43 units) marbling score  and lower percent USDA Select (16%) than CN, with DG intermediate for both traits; there was no significant difference in tenderness. The authors concluded that a high-starch pre-calving diet for dams might reduce intramuscular fat deposition and carcass quality grade of progeny after finishing.

[J. Animal Sci. 90:4962; Ohio St. Univ., Nat. Univ. of La Plata (Argentina), Univ. of Illinois]

A group of 90 steers initially averaging 541 lb was either not-implanted or implanted with a trenbolone acetate-estradiol with tylosin product (Component® TE-G with Tylan). Steers were then grazed for 84 days on cereal rye pasture. One-half of both groups above had access to either white salt blocks, non-medicated mineral block, or mineral block containing monensin (Rumensin®). Block consumption over the 84 days was 7.6 lb for white salt, 15.5 lb for non-medicated block, and 19.6 lb for medicated block.

Implanting alone significantly improved ADG (2.53 lb/day vs. 2.07 lb/day) as did monensin (2.49 lb/day vs. 2.11 lb/day). The non-monensin mineral block resulted in intermediate ADG of 2.31 lb/day, so a mineral block alone was of benefit above white salt. Using 2012 product costs and assuming value of $1.00/lb for weight gain, the authors calculated that implementing both implanting and medicated supplement increased net return by $60 per head.

(J. Animal Sci. 91 E-Suppl. 1:16; Noble Foundation, Ardmore, OK)

Elevated dietary levels of lipid and lipoprotein have been shown to adversely influence cardiovascular health. Four diets were evaluated in healthy adult men and women with elevated LDL-cholesterol levels:

  • Healthy American Diet (HAD):  33% total fat, 12% saturated fatty acid, 17% protein, 0.7 oz. lean beef/day;
  • Dietary Approaches to Stop Hypertension Diet (DASH): 27% total fat, 6% saturated fatty acid, 18% protein, 1.0 oz. lean beef/day;
  • Beef in an Optimal Lean Diet (BOLD): 28% total fat, 6% saturated fat, 19% protein, 4.0 oz. lean beef/day;
  • Beef in an Optimal Lean Diet plus additional protein (BOLD+): 28% total fat, 6% saturated fat, 27% protein, 5.4 oz. lean beef/day.

DASH, BOLD, and BOLD+ reduced total cholesterol and LDL-cholesterol. In addition, the BOLD and BOLD+ diets decreased lipoprotein, with BOLD+ having more decreasing effect. The authors concluded that the diets containing more lean beef “provide support for including lean beef in a heart-healthy diet”.

(Am. Jour. Clin. Nutr. 95:9; Penn. St. Univ., Okla. Med. Res. Found., Rutgers St. Univ.)

Records collected over 13 years were evaluated to compare performance of heifers born in the first 21 days (P1), second 21 days (P2), or third 21 days (P3) of a spring calving season. The following traits did not significantly differ: pre-weaning ADG, pre-breeding ADG, pre-calving weight, assisted births, calving difficulty score, cow weight at weaning, calf weight at weaning, and percent pregnancy after first calf.

Significantly differing results were as follows:

  • heifer birth weight: P1 highest;
  • heifer weaning weight: P1 highest, P2 intermediate, P3 lowest;
  • pre-breeding weight: P1 highest, P2 intermediate, P3 lowest;
  • % cycling at start of breeding: P1 highest, P2 intermediate, P3 lowest;
  • ADG during breeding: P3 highest, P1 lowest;
  • % pregnant: P1 highest, P2 intermediate, P3 lowest;
  • first calf birth date: P1 earliest;
  • first calf birth weight: P1 lightest.

The authors concluded “calving period of heifer progeny impacts development and first-calf characteristics”.

(2012 Nebraska Beef Cattle Report:18)

Residual feed intake (RFI) is a relatively new measure of efficiency in beef cattle. A group of 412 bulls of the Beefbooster, Inc., terminal-sire composite genetic line were evaluated for RFI. 24% of the bulls were culled for poor performance, type, temperament or other reasons and 21% were culled for poor Breeding Soundness Evaluation, for an overall cull rate after development of 45%. Of those culled on BSE, 41% were on semen quality, 36% on feet and legs, and 23% on scrotal circumference. Overall BSE score did not differ between high and low efficiency groups, but more high efficiency bulls failed to meet minimum standards for sperm motility.

Samples of high and low efficiency bulls were compared during two breeding seasons. Bulls of both efficiency groups were run together in multi-sire breeding pastures at cow:bull ratios of approximately 21:1. Sire of calf was determined by DNA analysis. Bulls from the high efficiency group sired a higher percentage of the calves. The authors concluded that selecting for high RFI efficiency was not detrimental to overall BSE score or breeding performance, but that further research is needed to evaluate sperm motility. (J. Anim. Sci. 90:2963; Univ. of Alberta. Univ. of Guelph)

Not like they once were. According to the Texas Cattle Feeders Association, in the TCFA area during the month of July only 5.5% of cattle were sold on a negotiated live/cash basis. The rest were sold on some other basis such as a formula or carcass value grid. Old-time cattle buyers might find this change hard to believe. Negotiated live/cash price is still the basis for some alternative pricing methods. There is some concern in the industry that a basis more representative of the total fed supply needs to be identified.

(TCFA Market Reports, month of July, 2013)

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