Beef Cattle Browsing – April 2009


Beef Cattle Browsing

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

April 2009

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.

There is considerable interest in purebred circles about curve benders, cattle that go against the normal growth curve. The perfect curve bender would have low birth weight (for calving ease), high weaning weight, high yearling weight, and low mature weight (for low cow maintenance cost). A recent study involving over 13,000 Red Angus records confirmed why bending the curve is difficult. In the study, genetic correlation between weaning weight direct (genetics for growth excluding maternal ability) and mature weight was 0.73. (There was essentially no correlation between mature weight and maternal ability.) So, genetics for growth to weaning was highly related to heavier mature weight. This has been shown before in numerous research studies.

How hard is it to find an extreme curve bender? The American Angus Association, among others, has a feature on their website that allows searches for sires with prescribed level of EPD. A search was made for sires in the top 10% for low birth weight, high weaning weight, high yearling weight, and low mature cow weight. The search found one sire out of the over 2200 listed. In fact, that sire was an outlier for most factors as shown below:

top 2% for direct calving ease
top 2% for birth weight (lightest)
top 5% for weaning weight direct
top 1% for yearling weight
bottom 15% for Frame Score (shortest)
top 25% for calving ease maternal
top 30% for maternal ability
bottom 6% for mature weight (lightest)
top 15% for ribeye area
top 25% for marbling
top 1% for $ Weaning Index
top 1% for $ Feedlot Index
top 25% for $ Carcass Grid Index
top 8% for $ Beef Index (combines Feedlot and Grid)

Did this Superbull have any downside? Yes, he was in the bottom 5% for scrotal circumference and the bottom 15% for fat thickness (that is, he was in the fattest end), which adversely affects Yield Grade and lowered this bull’s $ Carcass Grid Index. (But greater fat thickness in slaughter offspring could also mean easier-fleshing ability in the cow herd.) Two other bulls would have made the cut but they were only in the top 20% for low birth weight. Another nine bulls would have been included if the requirements were set at 25% instead of 10% for birth, weaning, yearling, and mature weights, but that’s still only about 0.5% of the bulls. So, you can find extreme curve benders but it’s not easy. (Genetic correlations from J. Animal Sci. 87:1628)

An Iowa report on effects of the bovine respiratory disease complex included 5976 cattle fed in 10 feedlots over four years. Cattle came from across the Midwest and Southeast. BRD was observed in 8.2% of all cattle and 61.9% of a subsample of 1665 carcasses had lung lesions. Cattle treated for BRD had significantly lower: 4-6 week starting-period ADG (by 0.81 lb/day), total feeding period ADG (by 0.15 lb/day), and final weight (by 24 lb). Also, treated cattle had lighter carcass weight, smaller ribeye area, less fat cover, and less marbling. Compared to cattle never treated, carcass value was lower for those treated once, twice, or three or more times by $23.23, $30.15, and $54.01, respectively. (J. Animal Sci. 87:1821)

The difference in price between Choice and Select carcasses varies over time. There have been periods when Choice brought $25/cwt carcass more than Select. Two years ago in April the difference was $9/cwt. But one year ago it was not quite $1/cwt. From mid-March to mid-April this year there was basically no spread. However, that doesn’t mean quality is not rewarded as there is consistently a bonus of about $6/cwt over Low Choice for premium programs (Certified Angus Beef, etc.) that require mid-Choice or higher. Why is the spread diminishing? Some of the reasons offered include heavier weight coming off feed, better genetics, instrument grading, and less disposable income available for higher-priced products. At any rate, it appears there is a limit to how many Choice cattle the market will take before relative value declines, or disappears. The National Beef Quality Audit of 2005-06 listed an ideal target of 69% Low Choice and higher. That may need to be rethought.

Four recent studies all deal with effects of Zilmax (zilpaterol hydrochloride). The effect of Zilmax with and without monensin and tylosin was studied in 3757 steers fed in the Texas Panhandle. Cattle were on feed for 161-167 days. Half of the cattle were fed Zilmax for 30 days until 5 or 6 days before slaughter. Half of each Zilmax group was fed monensin and tylosin for either the entire feeding period or not fed during the last 35 days. As other studies have shown, Zilmax increased ADG, feed efficiency, dressing percent, carcass weight, and ribeye area, improved Yield Grade, and decreased marbling score. Compared to feeding throughout, when monensin and tylosin were withdrawn the last 35 days on feed, marbling score decreased but Yield Grade improved. (J. Animal Sci. 87:1013).

In another Texas Panhandle study, Zilmax was fed for 0, 20, 30, or 40 days before slaughter with total feeding periods of 136, 157, 177, or 198 days. The same effects as reported above were found for feedlot and carcass traits. Marbling score tended to decrease as length of Zilmax feeding increased. Effects of Zilmax appeared to be independent of length of the total feeding period. (J. Animal Sci. 86:2005)

Another study in three locations (California, Idaho, and Texas) compared feeding Zilmax for either 20 or 40 days to controls. Effects were found for feedlot and carcass traits as reported in the two studies above. Decrease in marbling score was greater in cattle fed Zilmax 40 days compared to 20 days. Zilmax tended to adversely impact mechanical shear force and taste-panel estimates of tenderness, juiciness, and flavor intensity. (J. Animal Sci. 87:1374)

In a study conducted in Baja, Mexico, Zilmax was fed for 30 days and then withdrawn either 3, 6, or 12 days before slaughter. Longer withdrawal time reduced the Zilmax advantage in ADG and feed efficiency. (J. Animal Sci. 87:1759)

In summary, it appears clear that Zilmax increases gain, efficiency, and carcass leanness but with some penalty in marbling and eating quality.

Most of the ethanol produced in the U. S. comes from corn. A recent report by the Congressional Budget Office states that about one-fourth of the domestic corn crop is now used for ethanol production. That diversion of corn to ethanol accounted for about 10-15% of the increase in food price between April, 2007 and April 2008. Due to higher food prices, federal spending for the Supplemental Nutrition Assistance Program (SNAP, formerly Food Stamp Program) and child nutrition programs is expected to increase by $600-900 million dollars in fiscal year 2009. What have we got in return? About 4% less gasoline consumption and less than 1% lower greenhouse-gas emissions from the transportation sector, says the CBO. (U. S. Congressional Budget Office)

A recent report, funded by the Cattlemen’s Beef Board and the Beef Councils of 12 states, sheds some light on this question. Demand is measured as a combination of amount consumed and price paid. For example, if consumption increases and price stays the same then demand is said to increase. Beef demand increased for a long time before about 1980. At that time, demand started decreasing and continued through 1998. Demand turned around and increased from 1999 through 2004 but has decreased again since then. The study found that demand increases as consumer income rises. Price changes affect demand, but not one for one; a 1% increase in beef price results in only 0.4% decrease in beef demand. And demand is affected more by changes in the price of beef than changes in price of competing meats.

Food safety recalls adversely affect demand and can lower price, at least temporarily. Recalls are especially important in maintaining export markets. Negative reports on human health and nutrition reduce demand while positive reports are helpful. Convenience is a factor and seems to be related to the percentage of women working outside the home, which has gone from 53% in the early 1980s to 60% by the late 1990s where it has remained. Every 1% increase in female employment reduces beef demand by 0.6%. Conversely, a 1% increase in female employment increases demand for poultry by 0.6%. Also, a 1% increase in food consumed away from home results in 1.6% decline in beef demand, but the opposite is true for pork and poultry. In conclusion, the report noted that decline in consumer income and apparent increase in rate of personal savings indicate that demand for beef will decrease during 2009. (Kansas State University Dept. of Ag. Economics MF-2876)

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