PSV-17 - Measuring motivation for forage of finishing cattle fed high-concentrate diets using a short-term thwarting test
Tuesday, July 21, 2020
7:00 AM – 5:00 PM
Location: Poster Sessions
Beef cattle are commonly fed a high-concentrate, grain-based diet in the finishing period. Longer forage particles stimulate chewing and rumination, which may increase saliva production to buffer the rumen, mitigating a harmful drop in pH that can result from a high grain diet. Our objective was to quantify motivation of finishing cattle to access forage with a short-term thwarting test. We predicted cattle would show more interest in forage, versus an additional offering of their primary diet, during initial exposure and when access to this resource was thwarted. Sixteen finishing cattle were fed a high-concentrate primary diet (16% forage) ad-libitum. Twice per day for 4 days, cattle were exposed to 1 of 2 treatments for a maximum of 1 hr/exposure: 1) 100 g of beardless wheat hay (WH; n=7) or 2) 100 g of the primary diet (TMR; n=9). On the 5th day, the bins containing the dietary treatments were covered with a metal mesh that thwarted access to the contents while still allowing visual and olfactory contact. Interaction with and time spent in proximity to the bins were video recorded and feed intake recorded during days 1-4. T-tests did not detect treatment differences during the thwarting test in any behavioral response (p≥0.292). However, repeated measures analysis indicated that intake of the dietary treatments and interactions with the bin decreased over days 1-4 for WH cattle, while these same measures increased for TMR cattle (day*treatment, p≤0.001). These results suggest that animals were more interested in eating and interacting with additional high-concentrate diet than with a small amount of forage. Our findings may be explained by several factors, including that the TMR was highly palatable or that the inclusion rate of forage in the primary diet may have been sufficient, thus cattle showed little motivation for forage during the thwarting test.