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.
Editor: Dr. Stephen Hammack, Professor & Extension Beef Cattle Specialist Emeritus
PRUSSIC ACID IN TIFTON 85?
An apparently isolated incident of prussic acid poisoning in cattle grazing a pure stand of Tifton 85 bermudagrass was reported in late May in Bastrop County, Texas, resulting in 15 cattle deaths. Several popular media reports with incorrect or misleading information caused undue alarm among producers and the public in general. Tifton 85 is a hybrid bermudagrass released in 1992 by Dr. Glenn Burton at the USDA-ARS station in Tifton, Georgia. Dr. Burton also developed Coastal bermudagrass, released in 1943, at the Tifton station. Tifton 85 has the potential of producing prussic acid, but it has been planted on millions of acres throughout the South and no prior prussic acid problems have been reported.
This specific incident may have been due to a particular combination of conditions. The pasture was severely drought-stressed last year. After good rains over the winter and early spring, the pasture was moderately fertilized in April and received about five inches of rain over 30 days before the incident occurred. The pasture was in hay-harvest stage of growth. Generally, prussic acid poisoning has been associated with young flush growth after drought or growth following frost. Cattle had been off feed during the day before being placed on the pasture. Subsequent analyses of other Tifton 85 pastures in other areas of Texas have revealed no prussic acid. (Texas AgriLife Today, 6/26/12)
DRIED DISTILLERS GRAINS FOR BEEF COWS
Co-products of ethanol production are being used in large quantities for finishing cattle. Three experiments were conducted to assess the use of one of those co-products, distillers dried grains with solubles (DDGS), for beef cows. A group of 120 spring-calving cows initially averaging 1190 lb in Body Condition Score (BCS) 5.1 were maintained during late gestation-early lactation on free-choice tall-grass prairie hay of 5.6% CP. The following daily amounts (dry-matter basis) of supplements were combined and fed to individual cows in 3 feedings/week before calving and 4 feedings/week after calving:
- 1.7 lb DDGS (LO)
- 3.4 lb DDGS (MD)
- 5.1 lb DDGS (HI)
- 3.4 lb equal parts wheat middlings and cottonseed meal (WC)
- 0.5 lb cottonseed hull pellet (CH)
WC was included as a positive control and CH as a negative control. CP intake was the same for MD and WC. The trial included 106 days of gestation and 13 days of lactation.
Loss in weight and BCS was associated with supplementation level, ranging from 118 lb and 0.21 BCS for HI to 218 lb and 1.14 BCS for CH; MD and WC did not differ significantly. Cows that lost more weight and BCS during supplementation regained more during the 46 days from the end of supplementation to breeding. By the time calves were weaned in mid-October there were no significant differences among cow groups in weight or BCS. Percent cows cycling, AI conception rate, pregnancy rate at weaning, calf birth weight, and calf weaning weight did not significantly differ among groups, though weaning weight did tend to be higher from higher-supplemented cows. The authors noted that lack of statistical significance in these traits was not surprising in view of the relatively low number (20) of animals per treatment. It was concluded that DDGS is a feasible alternative to traditional supplements for beef cows. (J. Animal Sci. 90:2014; Oklahoma St. Univ.)
ALGAE – ANOTHER CO-PRODUCT SUPPLEMENT?
Researchers are investigating algae as a source of biofuel. After energy is extracted from the algae in the form of oil, a powdered residue or co-product remains. In some early-stage research, this co-product was fed to cattle at varying levels. The material is 20% crude protein but is also high in salt and ash content. Consumption was not reduced when mixed with distillers grains or cottonseed meal at levels up to 60%. Additional research is in progress. (http://today.agrilife.org/; Texas A&M Univ.)
TIMING OF DE-WORMING AND VACCINATION IN YOUNG CALVES
Calves averaging 288 lb at about three months of age were inoculated with stomach and intestinal larvae on day 1, 7, 10, 14 and 18. One group was dewormed on day 21, one group was dewormed on day 35 and one group was not wormed as a control. All calves were vaccinated on day 35 with modified live virus respiratory vaccine. Fecal egg counts, blood samples, and rectal temperatures were taken weekly. Control calves always had higher fecal egg counts. On day 88, blood samples were taken, all calves were challenged with IBR virus, and 7 blood samples were taken during the next 14 days.
All calves had elevated rectal temperatures during the last 7 days but temperatures were higher for control calves. The authors concluded that de-worming reduced parasite levels and decreased rectal temperatures after viral challenge, regardless of whether de-worming was done two weeks before or at vaccination. (J. Animal Sci. 90:1948; Colorado St. Univ., USDA-ARS Lubbock, TX and Beltsville, MD, Intervet – Schering Plough Animal Health)
GENETICS – ENVIRONMENTAL INTERACTION FOR GROWTH DUE TO DIFFERENCES IN ELEVATION
Cattle maintained above 5000 feet elevation can suffer from high-altitude disease or “brisket disease”, a noninfectious cardiac pulmonary condition. Data were analyzed on 77,771 purebred Angus cattle born in Colorado from 1972 to 2007. Using postal zip codes, cattle were characterized according to the elevation of their herd of origin. Low elevation was defined as 3000 ft to 5000 ft (on the eastern plains) and high elevation from 7000 ft to 9000 ft (in the Rocky Mountains). Cattle from intermediate elevation were deleted from the study. Traits analyzed were weaning weight and postweaning gain; 204 sires had weaning records in both elevations and 142 had postweaning records. A trait was created to estimate survival, with animals having weaning records but no yearling records designated as not surviving.
Weaning and yearling weight heritabilities (0.2-0.3) were similar to what has been reported in many prior studies. Genetic correlation between the two traits at the different elevations was in the range of 0.7-0.8. The same was true of genetic correlation between elevations for postweaning gain. There were favorable genetic correlations between gain and survival. The authors concluded there was evidence for interaction, indicating that rankings of sires for growth traits may not be the same at different elevations. (J. Animal Sci. 90:2152; University of Georgia, Polish Institute of Genetics and Animal Breeding)
EFFECT OF DISTANCE TRAVELED FROM AUCTION BARNS AND OTHER FACTORS ON HEALTH AND PERFORMANCE
Cattle are typically subjected to many forms of stress. One source of stress is transportation. Data were analyzed from 21 commercial feedyards located in the Central and South Plains on 14,601 groups of cattle from1997 to 2009. Groups analyzed were restricted to those of the same sex (bulls and steers grouped as males), averaging at least 500 lb upon arrival, with at least 20 head, and with information on origin. Overall statistics were as follows:
|Distance traveled, miles||433||342||0 to 1914|
|Arrival weight, lb||732||739||500 to 898|
|Days on feed||159||156||2 to 330|
|Group size||171||153||20 to 1439|
|Arrival sickness, %||4.9||1.1||0 to 100|
|Death loss, %||1.3||0.8||0 to 29|
|ADG, lb||3.1||3.1||0.4 to 5.3|
|Hot carcass weight, lb||809||816||344 to 1000|
Overall, the data illustrate the large amount of variation in cattle feeding. In general, longer distance traveled equaled higher sickness and death. Cattle arriving averaging less than 600 lb (assumed to be younger in age) had more sickness and death as did males compared to females. Cattle transported over 1650 miles during summer also had more sickness and death. (J. Animal Sci. 90:1929; Kansas St. Univ.)
SEXED VS. CONVENTIONAL SEMEN
Heifers (n=500) were fed melengestrol acetate (MGA) for 14 days and then injected with prostaglandin F2α (PGF). For the next three days after injection, heifers detected in estrus were AIed. After three days, heifers not detected in estrus were injected with gonadotropin-releasing hormone (GnRH) and mass AIed, with cleanup bulls turned in 12 days later. All AIed heifers received either conventional unsexed semen or semen sorted to produce 90% heifers. At 55 days after mass AI, pregnancy was determined by ultrasound.
Pregnancy rate was significantly higher for conventional semen, 58% vs. 41%, similar to what has been found in other research. (Overall pregnancy percent, AI plus natural service, was 93%). This, coupled with a cost for sexed semen of $45 vs. $14 for conventional semen, resulted in a higher cost per pregnant heifer of $44 for the sexed semen group. This extra cost should be compared to any benefit derived from producing mostly heifers. (2012 Beef Cattle Report, p. 20; Univ. of Nebraska)
STATUS OF COOL
The World Trade Organization has ruled that U. S. Country of Origin Labeling violates trade agreements by requiring more information from importers than is provided to consumers, resulting in a burden on importers without corresponding benefit to consumers. If the U. S. takes no action and continues to implement COOL as is this could mean other countries could legally take counteracting measures in the form of tariffs on some goods. Or, COOL could be modified to comply with WTO rules. Or, COOL could be dropped. The U.S. government will assess these findings and decide on a course of action, or not. More information on this decision can be found at www.wto.org.
BEEF CATTLE SHORT COURSE
The 58th Annual Texas A&M Beef Cattle Short Course will be held August 6-8 in the newly renovated Memorial Student Center on the campus of Texas A&M University. All aspects of beef production will be covered. For program information and registration go to http://animalscience-old.tamu.edu/ansc/BCSC/index.html or call (979) 845-6931.