An official website of the United States government.
<ul> <LI> To determine the effects of feeding zilpaterol hydrochloride on cull cow feeding performance including average daily gain, gain:feed ratio, live wight gain, body condition score, and body tissue compositional changes via ultrasonography <LI> To establish the efficacy of zilpaterol hydrochloride supplementation on cull cow carcass composition (lean, fat, and bone), carcass characteristics (including carcass yield and carcass quality attributes), and subprimal yields from nine major muscles from the chuck, rib, sirloin, and round. <LI> To evaluate the effects of zilpaterol hydrochloride supplementation on subprimal lean color, meat tissue proximate analysis, mechanical tenderness, pH, thaw loss, and cook loss of selected muscles. <LI> To determine the bacteriostatic effects of two antimicrobial compounds when included with enhancement solutions used to make whole-muscle, non-intact beef derived from cull cow carcasses. <LI> Deterimine the shelf-life stability, yield, and purge of steaks derived from cull cows that have been multi-needle injected with an enhancement solution containing antimicrobial products. <LI> Benchmark the tenderness and sensory (palatablity) attributes of two muscles from cull cows that have been injected with an enhancement solution containing antimicrobial products. </ul>The activities for these experiments will be conducted over the course of the next four and one-half years. It is expected that two graduate students, pursuing Master of Science degrees in Animal Science and Food Science, will work on these projects as part of the requirements to earn a Master's of Science degree. It is expected that the proposed works will elicit a minimum of 3-4 peer reviewed, refereed, journal articles. The data will also be disseminated at local and national scientific and lay meetings.
Non-Technical Summary: Cull market cows play a vital role in the economic health of the beef industry, especially to beef producers and beef packers in the Southeastern United States. At the point of sale, it is estimated that cull cows may comprise up to 25% of producer/ranch profits. At suggested culling rates of 10 to 15 % per year the sale of cull cows can mean the difference between a producer operation operating in the red or black. In 2006, 26.3 billion pounds of beef were produced in the United States, a 6% increase from 2005. Cull cows accounted for 16.1% of all beef animals slaughtered which equates to more than 5.3 million cows (2.4 million dairy cows and 2.9 million beef cows). Meat from cull market cows may comprise as much as 12.6% of the beef produced in the United States. Market cows are traded based upon percent lean largely because the most valuable product received from the carcass is lean trimmings that will go into comminuted products such as hamburger, sausages, or chopped and formed meats where lean content has the greatest impact on the value of raw materials used. Cows are culled for many reasons including terminal sickness, lameness, or poor productivity. Cows culled for the first reasons should be disposed of immediately. However, if a cow is culled due to lameness (not severe) or a decrease in productivity, her salvage value may be improved with minimal management inputs. Diagnosing early lameness is very important in the dairy industry where the cows are typically stalled on concrete which tends to exacerbate the issue. Removing these cows from concrete, dying them off and placing them on pasture with supplemental feed will decrease the physical demands on them, allow them to get in better condition and reverse some of the lameness issues that cost the market cow industry millions of dollars. Cows that are culled for productivity reasons are typically thin and in poor body condition. The average cull cow sold for slaughter in 2000 had a body condition rating of 4 or less. Cull cow body condition increased slightly in the 2007 Market Cow Audit, but the majority of cows still had a body condition of 4 or less which is too low to obtain maximum value. In a time of decreasing profits and increasing inputs it is extremely important that producers and processors take full advantage of management and marketing opportunities that increase their bottom line. Processors that focus on cull cow harvesting are currently exploring opportunities to utilize muscles for further processing as roasts or steaks in addition to lean trimmings, including whole-muscle, non-intact cuts. In order for this to be profitable, muscles must meet size requirements to justify the extra fabrication cost of muscle seam removal and must also be palatable and tender. Short-term feeding of cull cows prior to slaughter and post-harvest muscle enhancement technologies may be suitable methods to increase the pounds of lean a cow carcass produces and the overall palatability of the muscles derived from those market cows. <P> Approach: Exp 1. The effect of feeding zilpaterol HCL Market cows (n=40) will be sourced from local markets in north Georgia and transported to the research farm. Cows will be quarantined and monitored for illness for a 20 to 30 d period. During quarantine, cows will be vaccinated and e-wormed as routine procedures. Cows will be separated into two feeding replicates and randomly assigned within feeding replicated to one of two treatment groups of receiving zilpaterol HCL or not for the final 30 d of feeding. As well, within each feeding replicate treatment combination half of the cows will be randomly selected to receive a growth implant. Cows will be fed for a total of 60 d. At the end of feeding cows will be transported to an inspected harvest facility for routine slaughter. Carcass data pertaining to carcass yield and quality characteristics will be collected 24 h postmortem. Carcasses will be fabricated so that nine muscles of economic importance can be excised. These muscles will have weight, width and length measurements taken, as well as, pH and color. A small sample will be collected from each muscle for proximate analysis. Steaks will be cut from each muscle and aged or 7, 14, or 21 d for Warner-Bratzler shear force determination. All data will be analyzed using SAS. Live and carcass data will be analyzed as a randomized design. Muscle data will be analyzed as a split plot model with muscle serving as the split plot and carcass serving as the whole plot. Means will be separated at 0.05. Exp 2. Validation of pathogen intervention strategies Two muscles from cull cows that are commonly enhanced will be used to examine the antimicrobial properties and sensory characteristics of MOstatin and Ional when included with a brine solution. Muscles for the pathogen challenge will be inoculated with E. coli O157:H7 on the lean face and attachment will be allowed for 20 min. After attachment muscles will be injected to 110 percent of green weight and allowed to purge for 10 min. After purge muscles will cut in half and packaged. After 10 d cold storage half of each muscle will be sampled raw at three depth locations and half of the muscles will be cooked to internal temperature of 60 degrees C and sampled at three depth locations which will allow for monitoring of pathogen translocation. Samples will be diluted (peptone) and plated on TSAA for enumeration after 24 h at 37 degrees C. For quality aspects, muscles (non-inoculated) will be enhanced the same as before. Roasts will be put on retail display for 1, 7, 14, and 21 d in Styrofoam pads with PVC. Small samples will be collected on said days for TPC of psychotropic organisms. Color will monitored daily (objective and subjective) and on experimental days a sample will collected to measure lipid oxidation. Samples from d 1 will be cooked for sensory analysis and additional samples will be packaged and aged for 1, 7, 14, or 21 d for Warner-Bratzler shear force determination. Pathogen challenge portions will use GLM and Duncan's Multiple Range Tests. Sensory aspects of the experiment will used Least Squares Means from the Mixed procedures. Significance will be determined at 0.05.