David L. Morris: Vet Column 5-30-11 | TheFencePost.com

David L. Morris: Vet Column 5-30-11

David L. Morris, DVM, Ph.D.
Fort Collins, Colo.

Beef Quality Assurance has been an important part of beef production for the past 20 years. Since dairy producers derive 15 percent of their income from the sale of market cows, Dairy Beef Quality Assurance programs are also becoming increasingly important to maintaining and enhancing consumer satisfaction with beef products. Beef quality assurance issues and responsible production practices have also driven the development of newer animal health and production products.

With focus on injectable antibiotics, vaccines, anti-inflammatories, and other injectable non-hormonal products, less attention by many administering various injectable products to cattle has been paid to the use of common injectable hormone products such as prostaglandins (Lutalyse®, Estrumate®, IN-SYNCH®, etc.) and gonadotrophins (Cystorelin®, Factrel®, Fertagyl®, etc.). This occurs even though product labels and inserts direct attention to quality assurance reminders. Most, if not all, of the commonly used hormone products are clear, colorless, and, therefore, must be safe. Right?

Investigators from North Dakota State University and Texas A&M University recently published data assessing the tissue impact of injecting reproductive hormone products to cattle to answer that question. Cystorelin® (2 cc), Lutalyse® (5 cc), Banamine® (5 cc), saline (5 cc), and needle alone (20 gauge dry sterile needle inserted and removed) were used as treatments of intramuscular injections for this study. Ten health non-pregnant first-, second-, and third-lactation dairy cows less than

60 days after calving were enrolled in this study. None of the 10 cows had been treated for illness in the period since calving.

All injections were made in the two major muscles in the back of the rear legs. Banamine® intramuscularly is an extra-label use of the product, but because of its potential for tissue damage, it was used as a positive control. The assessment of muscle damage was made by measuring the concentration of creatine kinase, an enzyme associated with muscle damage, in the serum. Blood samples were taken immediately before the injection, and at two, four, eight, 24, 48, and 72 hours after injection.

Results of this study indicate that Lutalyse® and Banamine® caused more tissue damage than needle only, saline, or Cystorelin®. Although statistical significance did not find differences in tissue damage associated with Cystorelin®, it cannot be inferred from this study that no tissue damage occurred with the use of Cystorelin®. This study points out that volume may be a consideration in that 5 ml was used for injecting Lutalyse® and Banamine® and only 2 ml was used when injecting Cystorelin®. Further studies would be needed to determine if volume similarities in using a prostaglandin such as Estrumate® (2 ml) as compared to Cystorelin® would reveal any differences in tissue damage.

Upper hip and hind leg injections of reproductive drugs are used in 70 percent of dairy herds based upon the National Animal Health Monitoring System Dairy 2007 report. Based upon reported use, the average dairy cow through four lactations will be subjected to an average of 11 injections with reproductive drugs.

This present study indicates acute inflammatory muscle damage is associated with intramuscular use of 5 ml of Lutalyse®. It is important to note that longer term (more than 72 hours) damage; affected muscle tenderness assessments post-mortem; and testing other selected reproductive hormone products were not evaluated. Nevertheless, based upon this study, it cannot be assumed that no tissue damage is associated with using reproductive hormones intramuscularly.

Balancing beef quality concerns with human and animal safety should be a part of all cattle processing plans.

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