Contact with Humans and Grazing Intensity Influence Meat Quality in Beef Heifers

Meat quality is influenced by many animal-related factors. An Agroscope study shows that intensive grazing on smaller paddocks with a corresponding frequent change of paddocks and contact with humans is positively associated with meat quality.

Genetics, health status and locomotor activity of the animal as well as farm management and transport, slaughter and processing conditions influence meat quality. Pre-slaughter stress leads to physiological changes that affect meat quality. Consequently, measures that reduce stress reactions in animals and optimise meat quality are of interest. In addition, pasture rotation, and – as emerged from a previous Agroscope study on young fattening bulls – horn status can affect meat quality. The aim of the present study was therefore to investigate the effects and interactions of grazing intensity and horn status on the behaviour, physiological pre-slaughter stress levels and meat characteristics of beef heifers.

64 horned and disbudded heifers studied

The study was conducted with 32 horned and 32 disbudded crossbred heifers (Limousin x Dairy Breed (Swiss Fleckvieh, Red Holstein and Holstein)) grazed on alpine pastures during summer and slaughtered at the end of the summer grazing period. Agroscope researchers assigned the heifers to two different grazing systems. The first system consisted of high-intensity grazing on small paddocks of 0.24 ha, with stockpeople moving the heifers onto new paddocks every two to three days. The second group was grazed at lower intensity on paddocks three times this size, rotating between paddocks every seven to eight days. The groups were balanced in terms of body weight, dam breed, horn status and behaviour.

Pasture rotation and contact with humans have a positive effect

The effects of horn status and grazing intensity on physical activity on pasture, pre-slaughter stress and meat quality of the back muscle m. longissimus thoracis were investigated. The meat was assessed in laboratory tests inter alia for tenderness and water-holding capacity, in addition to undergoing sensory analysis by trained panellists. The heifers in the ‘high grazing intensity’ groups moved less on the smaller paddocks. The frequent paddock rotation of these groups led to greater contact with humans. Their stress levels were lower before stunning at the abattoir and accordingly, their meat exhibited lower water losses and faster degradation of the protein Troponin, both indicators of a better meat quality. The more frequent contact with humans may explain the lower pre-slaughter stress levels, and hence some of the effects on meat quality. Since grazing intensity involves more-frequent contact with humans during more-frequent paddock changes, it is not possible to differentiate between these two factors.

Horn status slightly affects meat quality

Compared to disbudded heifers, horned heifers had faster heart rates in the abattoir; their meat had lower cooking losses and was rated less juicy in the sensory analysis. Pre-slaughter heart rate correlated strongly with various meat-quality indicators; for example, the higher the heart rate at unloading at the abattoir, the higher the ultimate pH value of the meat (48 h post mortem). Generally speaking, once it exceeds a certain threshold, an excessively high ultimate pH value can negatively affect meat quality and ageing. In this study, however, the threshold was not exceeded.

This study convincingly confirms the extent to which pre-slaughter stress influences meat quality. Part of the effects may be associated with the different pre-slaughter physiological reactions which subsequently influence meat quality.