Beef Cattle Browsing
Editor: Dr. Stephen Hammack, Professor & Extension Beef Cattle Specialist Emeritus
April 2005
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.
NO BSE IN U.S. CATTLE – WHY?
Conventional wisdom says it is only a matter of time before BSE is diagnosed in cattle indigenous to the United States. Don Franco disagrees. Franco was formerly with USDA-FSIS, and is now President of the Center for Bio-security, Food Safety & Public Health. His key points are: 1) meat and bone meal (MBM) is assumed to be the reservoir for infection in BSE outbreaks worldwide; 2) the U. S. is a large exporter of MBM, and even any small amounts imported would have ceased with the ban in 1989 (USDA says no MBM was imported from the United Kingdom, the major source of BSE incidence, between 1980 and 1990); 3) 334 live cattle were imported to the U. S. from the U. K. between 1981 to 1989, but about half were disposed of and the rest came in before the peak of the U. K. epidemic and were not from any herd where BSE was confirmed; 4) 397 cattle were imported from other western European countries that have had BSE, but the vast majority of those came in before 1988; 5) over 235,000 adult cattle have been tested in the U. S. with no positives. Franco concludes that the U. S. is either free of BSE or at minimal risk, as does the Harvard/Tuskegee Risk Analysis Report.
DOLLAR VALUE INDEX EPD
Several breed associations are now calculating what have been termed “dollar value index” EPDs, which combine existing EPDs to produce overall selection indexes, stated in dollars worth of value. An example is a carcass value index, which combines estimates of carcass quality (based on EPD for marbling or ultrasound intramuscular fat), carcass cutability (based on EPD for yield grade or percent retail product), and carcass weight (using EPD for that trait). Periodically-updated prevailing carcass grid prices are applied for differences in quality and yield grade.
The American Angus Association has an index for weaned calf value ($W), and three terminal-sire indexes: feedlot value ($F); carcass grid value ($G); and total beef value ($B) which combines $F and $G. The American-International Charolais Association has a Terminal Sire Profitability Index, combining feedlot performance and carcass grid value. The American Hereford Association has: Baldy Maternal Index (BMI$), which assumes Hereford sires on Angus females; Brahman-Influence Index (BII$), similar to BMI$ except with Brahman females; Calving EZ Index (CEZ$), also similar to BMI$, except breeding yearling heifers; and Certified Hereford Beef Index (CHB$), a terminal-sire index with British-cross females and selling offspring as Certified Hereford Beef. The American Simmental Association has a Terminal Index (TI), for using Simmental sires on Angus females and selling offspring on a grid, and an All-Purpose Index (API) for using Simmental sires on Angus females (of all ages), with replacement heifers saved and remaining heifers and steers fed out and sold on a grid. Some of these indexes provide little additional information above the constituent EPDs, other than to state differences in dollar value. But some are more complex and almost total-system-based, most notably the Simmental API, which includes effects of all Simmental EPDs except for tenderness. (Source: breed association websites)
EFFECT OF PARITY AND MILK ON FORAGE CONSUMPTION
Oklahoma State researchers studied forage consumption before and after calving using Brangus females, 12 first-calf heifers and 12 cows that had calved at least once, with high and low Milk EPDs in both groups (sires of the females averaged + 10.0 for high-Milk and – 12.5 for low-Milk). Females were individually fed grass hay ad lib and protein supplement. Before calving, cows consumed 24% more forage than heifers, which was 1.7% of body weight for both groups, but Milk EPD did not affect consumption. After calving, forage consumption increased and cows continued to consume more forage than heifers, again in relation to body weight. Cows produced 66% more milk than heifers during early lactation and 84% more during late lactation. During early lactation, high-Milk EPD females produced 21% more milk and consumed more forage than low-Milk, but these effects did not persist during late lactation. Between the two Milk-EPD groups, there was more difference in milk production and forage consumption in heifers than in cows. In conclusion, heifers consumed about the same as cows in relation to body weight, but heifers have higher nutritional requirements because they are still growing. And females of higher Milk EPD, while producing more milk, consume more forage. (OSU Animal Science Res. Rpt. P-993:12 and 13)
ANTIBIOTIC RESISTANCE
Continued use of an antibiotic over time can result in development of resistance in bacterial populations to that antibiotic. There has been some concern that using the same antibiotics in food animals and humans might cause those antibiotics to be less effective in treating humans. An extensive review of 276 research papers on this subject has been published, authored by scientists from the United States, the United Kingdom, and Denmark. Based on this review, they concluded “although some antibiotics are used both in animals and humans, most of the resistance in humans has arisen from human use”, that “banning of any antibiotic in animals is likely to be wasted at best and even harmful”, and “efforts should be concentrated instead on minimizing transmission of all food-borne pathogens by insistence on good hygiene practices on farms, in abattoirs, during distribution and marketing, in food preparation, and by the consumer”. (J. Antimicrobial Chemotherapy 53:28)