استفاده از یک دروازه فشار پنوماتیک برای اندازه گیری انگیزه گاوهای شیری برای رها کردن در یک منطقه عمیق

Persistence of willingness to work has been used to measure the importance of resources and performance of species-specific behaviors. Our objectives were to develop and validate a “push-door” model to assess cattle motivation to lie down in a deep-bedded area. Motivation for lying was manipulated by forcing dairy cows to stand for 4 h/d in the hours before evening milking (Deprivation, n = 8) or not (No-deprivation, n = 8). Cows in both treatments were individually housed in pens divided into 2 areas: (1) with deep bedding and (2) with feed, water, a brush and wooden grids on the floor to discourage lying down. Cows pushed a one-way pneumatic gate in order to move from the feeding area to the deep-bedded area and could return via an unweighted, one-way gate. Once trained to use the pneumatic gate, the resistance required to open it was increased by 28 kg-f/d until cows no longer used it or the maximum resistance was reached (258 kg-f). We predicted that Deprivation cows would exert more effort to open the pneumatic gate, show a shorter latency to use it after evening milking, and would make fewer unsuccessful attempts compared to cows that were not deprived. We found that Deprivation cows used the pneumatic gate more frequently overall (6.8 ± 0.4 vs. 5.5 ± 0.4 bouts/d, respectively; P = 0.039) and sooner after milking (Deprivation: 29 ± 16 vs. No-deprivation: 95 ± 15 min/d; P = 0.004) compared to those with continuous access. As a result, a similar lying time of 13 h/d was maintained between treatments. There were no other differences, including in the maximum force pushed (Deprivation: 219 ± 14 vs. No-deprivation: 224 ± 11 kg-f; P = 0.992). Five cows pushed the maximum force (40% of average body weight of cows in this experiment), thus no ceiling price was reached for these individuals. This was despite that cows showed signs of physical limitations as the pressure on the pneumatic gate increased: they engaged in more frequent and longer duration of unsuccessful attempts to use it. For example, by the end, the cows tried, on average, to open the gate 19 times on the day they quit or reached the maximum (range 2–39 attempts for individual animals). Finally, once given free-access to the deep-bedded area, cows showed a rebound response, increasing their lying to 17.9 h/d, and reducing time spent feeding by 32% relative to previous days, illustrating their motivation to use this area. The results from this experiment indicate that increasing the resistance required to access a deep-bedded area until cows no longer used it or the maximum resistance was reached may underestimate the considerable motivation dairy cows have to access and lie down in a deep-bedded area.