Motivation of naïve feedlot cattle to obtain grain and individual responses to novelty

• Published in: Applied animal behaviour science 2017-12, Vol.197, p.68-74
• Main Authors: Van Os, Jennifer M.C., Mintline, Erin M., DeVries, Trevor J., Tucker, Cassandra B.
• Format: Article
• Language: English
• Subjects: Alfalfa; Animal behavior; Beef cattle; Bovidae; Carrots; Cattle; Confidence intervals; Diet; Energy consumption; Factory farming; Feeding; Feedlots; Grain; Hay; Latency; Motivation; Neophobia; Novelty; Proximity; Pushing; Studies; Studs
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/j.applanim.2017.09.001

•Beef cattle naïve to calf starter showed little motivation to consume it.•A tradeoff to obtain feed was imposed by adding an aversive feature to a push gate.•The degree of effort cattle expended was lower than previously shown.•Individual use of the push gate was associated with investigation of novel carrots.•Variation among cattle may reflect a personality trait (e.g. boldness, exploration). Beef cattle may be fattened before slaughter using a high-energy, grain-based diet. Although previous research suggests cattle prefer grain, their motivation to obtain this feed has not been quantified. The objective of this study was to evaluate the motivation of naïve feedlot cattle to consume grain relative to hay. One method for quantifying motivation is to allow animals to perform work (e.g., push a weighted gate) for access. However, as previous research has suggested gate pushing may be rewarding, a second objective was to evaluate whether adding an aversive element (protruding studs) to the gate would increase the cost of pushing. Twenty-four individually-housed Angus-Hereford heifers were fed Sudan and alfalfa hay (3:1 ratio) in an open feed bunk with unrestricted access. In a second bunk, 200g of either the primary diet (hay, final n=9) or calf starter (grain, final n=8) was fed behind a gate that required pushing for access. Additional weight was added to the gate at each feeding until heifers no longer pushed. We predicted heifers would show motivation to obtain grain by pushing heavier weights, showing a shorter latency to use the gate after feed delivery, and spending more time using the gate than those offered the additional portion of hay. Instead, heifers spent more time using the gate when offered hay vs. grain [back-transformed means: 0.4 vs. 1.8min/12h, respectively; 95% confidence intervals (CI): 0.1–1.0 vs. 0.9–3.3min/12h], likely because fibrous feed took longer to consume. Heifers offered hay or grain showed similar latencies to use the gate (back-transformed means: 88.6 vs. 59.8min, respectively; CI: 53.7–157.0 vs. 37.6–101.1min) and pushed similar maximum weights (mean±SEM: 15.0±1.8 vs. 18.2±1.9% of bodyweight). The heifers offered hay demonstrated contrafreeloading by working to obtain a resource that was simultaneously and freely available. To further evaluate responses to novelty, we recorded the amount of time each heifer spent in proximity to (within a 1-m radius) and investigating (in proximity and with the head