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.
BAN ANTIBIOTICS FOR GROWTH PROMOTION IN LIVESTOCK ?
Yes, according to recent action by the American Medical Association. Previously, the AMA had urged that antibiotics for non-therapeutic use in livestock be phased out or terminated. Now, at their recent annual meeting, the AMA took a stronger stance by adopting a resolution for such a ban “in order to slow antibiotic resistance in harmful bacteria”.
While recognizing there is overuse of antibiotics in hospitals and by some physicians, the head of the AMA Keep Antibiotics Working committee said, “as much as 70 percent of use in agriculture is unnecessary or overused”. The AMA recognized that therapeutic use of antibiotics for livestock is necessary, but the resolution called for a requirement that any antibiotics for animals be by prescription only by a veterinarian in valid client-patient relationship.
(2014 Annual Meeting of American Medical Association, Resolution 513)
INFLUENCE OF LINE 1 HEREFORDS
Line 1 Hereford cattle were created beginning in 1934 at the USDA Miles City, Montana research station using two half-sib bulls and 50 unrelated females. The line was closed at that time to outside breeding and is still maintained. Selection of sires has been based on growth, i. e., increase in body weight from birth to one year of age. Though soon to come, preference for smaller, early maturing breeding stock had not taken hold of the industry in 1934 and the cattle used to create the line were considered to be large framed at the time. Pictured below is one of the bulls used to start the line.
Beginning in 1948, some cattle were sold to outside breeders, especially in Montana. However, because the line was larger than cattle typically preferred at the time they generally were not in high favor in the breed nationwide until the 1960s, when intense interest developed in increasing size of cattle. Line 1s became a hot item.
A recent study evaluated the current impact of Line 1 in the breed by accessing pedigree information from the American Hereford Association on approximately 14,000,000 cattle. Five random samples were drawn for analysis. For animals registered in 1980, 23.2 % showed some influence of Line 1 breeding. By 2008, 81.4% showed Line 1 influence. The authors noted that extrapolation of this trend indicates that all Hereford cattle registered in 2020 will be related to Line 1. Concentration of Line 1 influence is highest in the Great Plains and eastern Corn Belt, but there are animals with Line 1 influence in 48 states, and numerous foreign countries.
(J. Animal Sci. 92:2387; USDA-ARS, Miles City, MT)
EFFECT OF QUALITY GRADE AND COUNTRY OF ORIGIN ON CONSUMER SATISFACTION
USDA Choice, USDA Select, Canadian grade AAA, and Canadian grade AA boneless strip loins were sourced from packing plants in Plainview, Texas, Amarillo, Texas, Garden City, Kansas, Greeley, Colorado, High River, Alberta, Brooks, Alberta, and Guelph, Ontario. Cuts were received vacuum packed, aged for 21 days, and then 1-inch steaks were cut. Steaks were frozen and sent to Lubbock, TX, Phoenix, AZ, and Baltimore, MD for consumer evaluation after grilling.
Consumer ratings were not significantly different for USDA Choice compared to Canadian AAA nor for USDA Select compared to Canadian AA; Choice/AAA was rated higher than Select/AA. Most consumers said they thought Canadian beef quality and safety did not differ from that of U. S. beef. Only 1.1% of consumers indicated that Country of Origin Labeling was a factor to them in purchase of beef.
(J. Animal Sci. 92:3685; Texas Tech Univ.)
EFFECT OF DELAYING INSEMINATION OF NONESTROUS COWS WITH SEX-SORTED SEMEN
When using sex-sorted semen, best results are obtained when detecting heat as opposed to fixed-time artificial insemination (FTAI) after synchronization. However, FTAI has become more common, especially in commercial herds, so greater use of sexed semen for FTAI will probably require improvement in pregnancy rates.
A study was conducted to see if delayed insemination of nonestrous cows would improve conception. A group of 656 crossbred lactating beef cows (averaging 6.5 years of age and 5.3 Body Condition Score) at 5 locations received the 7-day CO-Synch + controlled internal drug release (CIDR) protocol. Estrous detection aids were applied 7 days after the protocol was initiated; 51% of cows were nonestrous. Cows were then assigned to one of three treatments:
– 1) FTAI with non-sorted semen 66 hours after CIDR removal regardless of estrous expression;
– 2) FTAI with sex-sorted semen 66 hours after CIDR removal regardless of estrous expression;
– 3) FTAI with sex-sorted semen 66 hours after CIDR removal for estrous cows and 86 hours after for nonestrous cows.
Pregnancy rates were as follows:
|COW CATEGORY||TRT 1||TRT 2||TRT 3|
The authors concluded “delaying AI from nonestrous cows by 20 hours from the standard FTAI improves pregnancy rates when sex-sorted semen is used with AI”. However, in this study, as in some others, pregnancy in estrous cows was still lower with sex-sorted semen.
(J. Animal Sci. 92:1747; Univ. of Missouri)
IS USDA FRAME SIZE ACCURATE?
Frame (skeletal) Size has been part of USDA Grades for Feeder Cattle since 1979, along with estimates of Thickness (muscling in relation to frame size). There are three Frame Sizes, Small, Medium, and Large. Frame Size is only an indirect estimate of skeletal size. Rather, Frame Size estimates finished (0.5 inch fat cover) weight. The grades issued in 1979 defined Medium Frame steers as being projected to finish at 1000 lb-1200 lb, with Small below that range and Large above. The standards were revised in 2000 such that Medium is now projected to finish at 1100 lb-1250 lb, with Small below that and Large above. Heifers are projected to finish 100 lb below equivalent steers. USDA Frame Size is often confused with Beef Improvement Federation Frame Score. Frame Score is based only on hip height at the same age. Frame Size is based on projected uniformly-finished weight.
Data were analyzed from 16,700 steers and 6,357 heifers originating from 16 Midwestern and Southeastern states from 2003-2011. Cattle were fed in 17 feedlots in southwest Iowa and slaughtered in one plant in western Iowa. Cattle were evaluated for Frame Size by trained USDA or state personnel at point of origin or arrival at the feedlot. Initial weights and ages averaged 649 lb and 299 days for steers and 627 lb and 325 days for heifers. However, across the entire steer and heifer data sets there was extreme variation.
Cattle were implanted initially and 70 days before projected slaughter and those finishing later (46% of the total) received Optaflexx®. Cattle were slaughtered when individually estimated live to have 0.45 inch fat cover. Actual fat cover in the carcass averaged 0.45 inch for steers and 0.49 for heifers. Final weight then was adjusted to 0.5 inch fat cover, as is described in the USDA Feeder Grades. Comparisons were made between initial visually-estimated Frame Size and Frame Size based on fat cover-adjusted final weight as shown below:
|Small||1% 15%||1% 10%|
|Medium||37% 51%||46% 58%|
|Large||62% 35%||54% 32%|
1 = Visually estimated at start of feeding
2 = Based on final weight adjusted to 0.5 inch fat cover
The authors noted that the most recent (2012) National Beef Quality Audit indicates the majority of finished cattle now are Large Frame. With this in mind, and considering their data, the authors concluded that “application of the present USDA Frame Size system accurately categorized cattle near the middle of the population” but “lack of significant numbers of cattle closer to the extremes resulted in increased variability in accuracy of prediction of outcome for cattle categorized as Small Framed”. NOTE: Considering the paucity of Small Framed cattle in today’s national herd, the latter finding in this report is evidently of little practical importance.
(J. Animal Sci. 92:2654; Kansas St. Univ.)
WHICH STEAK IS BEST ? – FRESH, FROZEN, OR AGED ?
Strip loin and eye round untrimmed subprimals were obtained from 35 U. S. Select beef carcasses. One-inch thick steaks were cut, vacuum packaged, and assigned to one of the following treatments:
– 1) aged 2 days;
– 2) aged 2 days then frozen and thawed;
– 3) aged 2 days, frozen, thawed, then aged 12 days;
– 4) aged 14 days;
– 5) aged 14 days then frozen and thawed;
– 6) aged 14 days, frozen, thawed, then aged 14 days;
– 7) aged 30 days.
Aging was at 35 deg. F. Thawing was at 41 deg. F. for steaks frozen and 35 deg. F. for steaks frozen, thawed, then aged. Freezing was at minus 15 deg. F.
Tenderness of strip loins was significantly different and declined from most tender to least tender in the following treatment order: 6>3 and 7>5>2 and 4>1. Tenderness for eye rounds also was significantly different, and declined in the following order: 6>3, 5, and 7>2 and 4>1. Tenderness of strip loins was greater than eye round for treatments 3, 6, and 7 but eye round was more tender for treatments 1 and 2.
The authors concluded “these results indicate that freezing and thawing or freezing, thawing, and aging increase tenderness and may be a viable option to improve the consistency of meat tenderness” and “freezing is not likely to be adopted industry-wide, but there may be niches where the advantages outweigh the disadvantages”.
(J. Anim. Sci. 92: 2735; U. S. Meat Animal Res. Ctr.)
CAN LEAN BEEF BE “HEART HEALTHY?”
The DASH (dietary approaches to stop hypertension) program calls for a diet high in fruits, vegetables, and low-fat dairy products along with more protein from plant sources. A study was conducted to examine inclusion of lean beef in such a diet. For 5 weeks, 36 normotensive people, averaging 116 ± 3.6 mm systolic blood pressure (SBP), received either a “healthy American diet” (HAD) or one of the other diets shown below:
– HAD) 33% total fat, 12% saturated fatty acids, 17% protein, 20 g beef/day;
– DASH) 27% total fat, 6% saturated fatty acids, 18% protein, 28 g beef/day;
– BOLD) 28% total fat, 6% saturated fatty acids, 19% protein, 113 b beef/day;
– BOLD+) 28% total fat, 6% saturated fatty acids, 27% protein, 153 g beef/day.
SBP decreased significantly in BOLD+ compared to HAD. There was no significant effect for DASH or BOLD. There were no significant effects on diastolic blood pressure or peripheral artery tone. The authors concluded that, “The inclusion of beef in a heart healthy diet decreased SBP in normal individuals”.
(Jour. Of Human Hypertension, 6/19/14; Pennsylvania St. Univ., Rutgers Univ.)