Beef Cattle Browsing – January 2010

Beef Cattle Browsing

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

January 2010

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.

What effects on livestock production might result from climate-change legislation currently being considered in Congress? Joseph Glauber, chief economist for USDA, recently addressed this topic while appearing before the U. S. House Agriculture Subcommittee on Conservation, Credit, Energy, and Research. Glauber predicted that conversion of cropland to forests over time would result in prices that would be higher for commodities and lower for cattle and hogs. Compared to not passing legislation being considered, his estimates for 2015 (and 2030) if the legislation passes were:

  • corn production lower by 1.4 percent (and 7.2 percent);
  • corn price higher by 7.1 percent (and 15.6 percent);
  • soybean production lower by 3.5 percent (and 9.0 percent);
  • soybean prices change little;
  • fed beef production decrease 0.4 percent (and 3.4 percent);
  • fed beef price increase 1.2 percent (and 3.9 percent);
  • hog production decrease 5.7 percent (and 9.9 percent);
  • hog price increase 4.4 percent (and 12.1 percent).

(Testimony before U.S. House of Representatives subcommittee, 12/03/09)

This question was examined in a sample of 290 Angus sires. Their EPD accuracy was at least 0.50 and ranged up to 0.97. Records were available from 332,162 progeny and contemporaries. Correlations were low between scrotal circumference (SC) EPD and either intramuscular (IMF) fat EPD or marbling score (MS) EPD. Correlations were also low between SC EPD and EPDs for size (birth weight, weaning weight, yearling weight, yearling hip height, and mature weight). As expected, correlations between EPD for IMF and MS were very high. SC was a statistically significant predictor of MS, but explained only 1% of the variation. (This is another example of the fact that something can be statistically significant but of little biological or economic importance.) The authors concluded that selection could be made for SC without much influence on size or carcass traits. (Kansas State Univ., J. Animal Sci. 86 Supple. 1:191).

A group of 88 calves were purchased from several auction barns, shipped as a group, processed upon arrival, and treated as follows: 3 ml of 10.8 mg Zn/ml sprayed into each nostril (NS); 40 ml of 16.25 mg Zn/ml oral drench (DR); or no-zinc control. Groups were then maintained in pens for 43 days, with no fence line contact between pens. Signs of respiratory disease were monitored daily and rectal temperatures recorded. Calves from each pen were randomly selected for nasal swab collection on arrival and 2, 4, and 7 days later. NS calves gained less for the first 28 days. NS has fewer bacteria in nasal swabs. Final weight and sickness did not differ among groups. Zinc treatment did not appear to offer any overall performance or health benefit. (Univ. of Arkansas; Research Update Dec/09)

American Angus Association data were analyzed to determine genetic relationships among female weights at weaning, yearling, 2-, 3-, 4-, and 5-year-olds. Numbers ranged from 81,525 weaning weights to 7,546 for 5-year-olds. Genetic correlation between weaning and yearling weight was 0.84. Correlations between weaning weight and older weights ranged from 0.66 for 4-year-old to 0.72 for 2-year-old. Correlations between yearling weight and older ranged from 0.77 for 5-year-old to 0.85 for 2-year-old. Correlations among the four older weights were all greater than 0.98. This study confirms the high relationships between weights at different ages, and does so with a huge dataset.

Some steedstock producers are attempting to select for increased weaning and yearling weight without increasing mature cow weight, to create what are often termed “growth-curve benders.” These correlations between weaning and, especially, yearling weight with older weights demonstrate the difficulty, but not impossibility, of creating curve benders. (Univ. of Georgia; J. Animal Sci. 87 Supple. 2:497)

Zilpaterol hydrochloride (Zilmax®, ZH), fed for the last 20 to 40 days before slaughter, has been shown to improve average daily gain, feed efficiency, and carcass leanness. A group of 10 research studies addressed the effect of feeding ZH on beef composition and quality. Some of the important findings from the 10 studies were:

  • lean percentage was increased with ZH feeding
  • ZH feeding tended to increase percent lean more in the round than the loin
  • shear-force tenderness decreased as length of ZH feeding increased
  • combining ZH and an estrogen-trembolone acetate implant (Revalor®) reduced tenderness more than ZH alone
  • taste-panel estimates of tenderness and juiciness were lower with longer periods of ZH feeding
  • percent intramuscular fat (marbling) decreased, especially with longer ZH feeding
  • protein percentage was higher in steaks and ground beef with ZH feeding
  • color of steaks tended to be the same or better from cattle fed ZH for 20 to 30 days but not if fed for 40 days
  • 20 days of ZH feeding seemed to be optimum for increasing lean weight and percent lean while minimizing decreases in meat palatability.

(Cal Poly State Univ., Kansas State Univ., New Mexico State Univ., Oklahoma State Univ., Texas A&M Univ., Texas Tech Univ., Univ. of California, Univ. of Illinois, West Texas A&M Univ.; J. Animal Sci, 87:3669, 3677, 3686, 3702, 3712, 3722, 3730, 3739, 3751, 3764) 

If you’re interested in grass-fed production and marketing a handbook is available at covering all aspects including identifying opportunities and barriers, grazing systems, direct marketing, processing and added-value cuts, consumer interest and demand, and nutrition and carcass quality.

The concept of whole genome selection is being advanced by some as the ultimate answer to genetic improvement of beef cattle. This subject was addressed in a recent research paper.

The beef cattle industry is characterized by a diverse assortment of breeds, division of production segments, and little vertical integration of those segments. Beef cattle genetic evaluation programs are operated by breed associations, using data provided by producers who register seedstock. Seedstock producers react to the needs and desires of their customers, primarily commercial cow-calf producers buying bulls. Many of the traits of economic importance to feeders, processors, and retailers have little if any economic importance to cow-calf producers.

Effective whole genome selection could provide genetic information on all traits. This would require development of base phenotypic and genotypic populations involving thousands of animals. And genomic prediction equations would need to be validated under different production conditions and for various breed combinations. Costs for all of these functions must be borne by someone. Time will tell if the potential of whole genome selection will be realized in the beef cattle industry. (Univ. of California; J. Animal Sci. 87 Suppl. 2:175)

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