Carcass weight, meat quality and economic impact of liver fluke infection on cattle

Abstract

Liver fluke infection in cattle is typically sub-clinical, with animals lacking in visible clinical signs. Consequently, farmers are often dubious about investing in control measures as they are often unaware of its deleterious effects on meat quality and weight gain. The aim of this study was to quantify the effect of liver fluke infection on carcass weight and meat quality in Australian cattle, and, in turn, to estimate the economic loss to the producer. This study utilised abattoir data obtained from an Australian meat processor. The data encompassed observations of over 4 million cattle processed between 2016 and 2020. Six response variables were considered: the carcass weight, fat depth, AUS-MEAT marbling, muscle area, Meat Standards Australia index and ossification age days. The large volume of data, combined with a high degree of diversity in management practices and animals, meant accurate estimation of the effect of liver fluke infection was challenging. A generalised random forest model was used for heterogeneous causal effect estimation, while adjusting for relevant confounding variables and accounting for complex variable interactions. Substantive differences in the effect of liver fluke infection were found across groups of animals, with hormonal growth promotant free (HGP-free) animals sourced from properties being the most negatively impacted in terms of the carcass weight and meat quality. The expected loss for the producer per animal infected with liver fluke was estimated to be $A\text{\$}35$ (95 % CI 26, 43) for Angus females and $A\text{\$}32$ (95 % CI 24, 41) for Angus males (both HGP-free and sourced from properties). Based on the results of this study, it is recommended that cattle producers operating in high-risk regions carefully consider the relative benefits of liver fluke treatment and control.