The effect of intramuscular injection of dinoprost or gonadotropin-releasing hormone in dairy cows on beef quality1

Abstract

Intramuscular injections of drugs and vaccines cause tissue damage and subsequent effects on tenderness and consumer acceptability of beef. In the 2007 National Market Cow and Bull Beef Quality Audit, 100% of plants reported fabricating subprimal cuts such as rib eyes and tenderloins from cow and bull carcasses. Dairy beef quality should therefore be a consideration when injections are given to dairy animals. The discussion about injection site reactions and tenderness has focused on vaccines and antimicrobial drugs with little concern for the effects of reproductive hormones. The objective of this study was to quantify antemortem the effects of semimembranosis/semitendinosis muscle injection of dinoprost and GnRH in lactating dairy cows by estimating the weight of tissue damaged and comparing that with a drug known to cause extensive tissue damage, flunixin meglumine. Tissue damage was estimated from previously reported equations for grams of muscle tissue damage based on area under the curve of serum concentrations of the muscle enzyme creatine kinase over time. Dinoprost and flunixin injection both caused a significantly increased estimate of muscle tissue damaged compared with needle only (P = 0.0351 and 0.0355, respectively). Dinoprost and flunixin caused a marginally significant increased muscle tissue damage compared with GnRH (P = 0.1394 and 0.1475, respectively). No statistically significant difference was found between the estimated weight of muscle tissue damaged by flunixin compared with dinoprost (P = 1.0000), or by saline compared with GnRH (P = 0.7736) or needle only (P = 0.4902). The assumption that reproductive hormones are less damaging than vaccines and antimicrobial drugs should be examined more closely, including postmortem evaluation of injection site lesions and effects on tenderness.

Injection‐site lesion prevalence and potential risk factors in UK beef cattle

“…It could therefore be hypothesised that antibiotics and anti-inflammatories, which tend to be injected in higher volumes in cattle, would be more likely to cause ISLs than vaccines that are injected in relatively small (2–5 ml) volumes. Reproductive hormones are also administered in 2–5 ml doses but have been demonstrated to be damaging to meat quality in a study using creatine kinase levels as a marker of muscle damage following injection (Fajt and others 2011). …”

Luteolysis after the intravulvosubmucosal injection of prostaglandin F2α in cattle: Systemic or local mechanism?

“…We also demonstrated with a large number of animals that the dose of PGF 2a could be reduced when using the 10-day, 1-injection management system. The IVSM route could be useful to avoid the muscle tissue damage caused by dinoprost (Fajt et al, 2011) when applied in commercial systems. Furthermore, the reflux of a small volume (1 mL) is more likely when administering the drug through the IM route when compared to the IVSM route.…”

The complex relationship between welfare and reproduction in cattle

“…The fact that the timed AI synchronization protocols include repeated injections of hormones comes with short-term pain and distress associated with the injections and handling. Further, intramuscular injections may cause muscle tissue damage (Fajt, Wagner, Pederson, & Norby, 2011) and lead to bruises or abscesses.…”