A thwarting test, where animals are able to interact with feed but not consume it, can be used to measure how valued the resource is. It is expected that feedlot cattle will be motivated to access additional roughage because of its potential to alleviate symptoms of ruminal acidosis caused by high-concentrate rations. The objective of this study was to measure how motivated cattle fed a high-concentrate diet are to access additional forage, when offered it freely for 8 short exposures before being prevented from consuming the resource, in a thwarting test. Eighteen animals, fed a finishing ration ad-libitum, were offered a small amount of either beardless wheat hay (WH; n=9) or their primary diet (TMR; n=9) in a plastic bin twice daily for a maximum of 1 h over 4 d (exposures 1-8). Then on the 5th day (thwarting test), animals were given access to but prevented from consuming their treatment diet by covering it with wire for 30 min. There was no evidence of treatment differences detected during the thwarting test. This may indicate there was adequate roughage in the primary diet to satisfy motivation for thwarted WH. Animals were quick to approach the treatments (average latency less than 30 s) during the test, possibly indicating motivation to access both. Unlike the thwarting test, behavioural responses to the treatments differed in the exposures, when cattle showed more interest in the TMR than the WH. Interacting with the bin by moving it with their muzzles was observed more often for TMR animals than WH animals in exposures 7 and 8 (P=0.07 and 0.04, respectively). There was no evidence that latency to approach the bin differed by treatment or exposure (P>0.1). These findings provide some evidence in support the theory that animals will seek out a high-energy diet such as the TMR, because it is more calorically-dense, and likely more palatable. However, these data do not support the hypothesis that finishing cattle will be more motivated to access WH than TMR when thwarted from doing so.

Please see the associated research publication for methodological details. 

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