The effects of confinement environment on reproductive efficiency in the baboon

Historically, to supply animals for medical research, both captive-bred baboons and imported wild-caught animals have been available. Now that imported animals are difficult to obtain, it is important to maximize domestic production. To this end, it is necessary to determine the optimum housing conditions (i.e., environmentally dependent factors) under which baboons have the greatest reproductive efficiency. At our institution, the Oklahoma University Health Sciences Center Primate Facility, we recently moved the majority of our baboon breeding colony into a large indoor-outdoor facility (El Reno) from a small, indoor facility (Annex). Fortuitously, this move allowed a direct comparison of baboon reproductive efficiency between the two radically different environments. The environment at the Annex is exclusively indoor and possesses limited but adequate living space (per Guide for the Care and Use of Laboratory Animals recommendations), whereas the El Reno environment is indoor-outdoor and naturalistic with living space exceeding Guide recommendations. Although we expected animals at the El Reno facility to exhibit somewhat increased reproductive efficiency, the magnitude of the increase was surprising: the mean number of days post-partum to first estrus was 165 for animals housed in the Annex, but 69 for those at the El Reno facility. In addition, the mean number of days from first estrus to conception was 61 for baboons in the Annex compared with 47 for those at El Reno, and the mean number of days from conception to next conception was 403 for animals in the Annex but 296 for those at El Reno. These results demonstrate that a change in housing environment can dramatically increase baboon breeding efficiency.