Improved Training and Semen Collection Outcomes Using the Closed Box Chair for Macaques

SIMPLE SUMMARY: Refining procedures is an important part of promoting animal welfare. One area in which refinements are particularly important is animal restraint. Monkeys and other animals may be restrained for a variety of reasons, including sperm collection. In this study, we compared the use of a closed box chair (CBC) as a potential refinement over the more traditional open restraint chair (ORC) for restraint. We trained 34 male rhesus macaques to enter either the CBC or the ORC, allow restraint, and provide a semen sample. While all monkeys were reliably trained for the CBC, only 75% completed the task in the ORC. Further, it took longer to train the monkeys for the ORC than the CBC. Importantly, monkeys restrained in the CBC produced a higher ejaculatory volume and a higher sperm concentration than those in the ORC. Taken together, these data suggest that the CBC reduces stress for the animals while improving scientific outcomes, and thus is a refinement over the ORC. ABSTRACT: Collaborative semen collection in monkeys is a valuable tool in research, animal collection management, and conservation efforts. To obtain samples, monkeys are often restrained in open restraint chairs (ORC) with the “pole and collar” technique. While commonly used, this restraint is not tolerated by all individuals; some become anxious or aggressive towards the poles and people. In an effort to refine this procedure and improve welfare of the monkeys, we examined the use of a “closed box chair” (CBC), a clear, plexiglass box in which the monkey is trained to sit for sperm collection. The CBC does not require pole and collar, and although legs are secured, the arms and neck are not restrained. The use of CBCs has increased in recent years; however, there are few studies demonstrating its effects on scientific outcomes. We used positive reinforcement techniques to train 34 adult male rhesus macaques (Macaca mulatta) to provide semen samples using either the ORC or the CBC. While all CBC monkeys (n = 14) were reliably trained for this procedure, only 75% of ORC (n = 20) males completed the training (p = 0.04). It took significantly less time to train animals in the CBC than the ORC (201.0 vs. 412.4 min; p <0.001). In a controlled subset, males restrained with ORC (n = 7) produced a significantly lower ejaculatory volume than those collected by CBC (n = 10) (297.6 µL vs. 522.1 µL respectively; p = 0.04) and had a lower concentration of sperm (186.0 × 10(6)/mL vs. 367.5 × 10(6)/mL respectively; p = 0.017), although there were no differences with respect to sperm motility (p = 0.15). Our data suggest the closed box chair technique reduces stress on the animals while enhancing semen quality, supporting the use of the CBC as an important refinement.