Effect of Different Reproductive Stages and Culture Times on Domestic Cat <i>in Vitro </i>Oocyte Maturation

The domestic cat has been used as a model to carry out comparative research in assisted reproduction, to be applied in wild cats. The efficiency in domestic cat IVM concerning the reproductive status and/or cultivation times has previously been investigated;however, the studies were carried out separately. The objective of this research was to evaluate the maturation of oocytes of domestic cats of different reproductive stages using two different in vitro culture times. The ovaries were obtained by Ooforo-Salpingo-Hysterectomy of cats that were of the following groups: 1) prepubertal, 2) follicular, 3) pregnant or 4) in anestrus. Maturation was carried out with TCM199 medium supplemented with BSA for 24 h and 48 h. On average, 29 ± 25, 20 ± 15, 17 ± 9 and 17 ± 13 oocytes/cat were recovered from the prepubertal follicular, pregnant, and anestrus stages, respectively, but did not show a significant difference (P > 0.05). Also, meiotic maturation did not show a significant difference between the different reproductive stages at 24 h and 48 h, respectively (P > 0.05). However, in the prepubertal and follicular stages, greater oocyte maturation numbers were observed at 48 h compared to 24 h (P < 0.05). In contrast, the aforementioned result was not observed in the pregnant and anestrus stages (P > 0.05), indicating that the in vitro culture duration is an important factor during in vitro maturation of domestic cat oocytes.

Dynamic Vertical Climbing Mechanism of Chinese Dragon-Li Cats Based on the Linear Inverted Pendulum Model

Humans have long desired but never achieved the capacity to climb walls.The fundamental reason is that human hands and feet cannot climb vertical walls like geckos and bees.Animals lacking an adhesive structure can use the body’s dynamic effect to climb walls.Here we investigated the dynamic wall climbing behavior of individuals who cannot remain stationary on the vertical wall.Taking the domestic cat as the experimental object,we constructed an experimental platform as the obstacle for the cat to climb the wall.Our research indicated that domestic cats must meet the following physical conditions to do dynamic vertical wall climbing:vertical obstacles must have nonvertical surfaces,a horizontal run-up,and contact with nonvertical surfaces before the vertical speed reduces to zero.Here we proposed a dynamic vertical wall climbing model with three contact states based on an investigation of domestic cats’dynamic wall climbing behavior and the LIP model.The motion range of the LIP model’s generalized angular coordinates varies depending on the contact state.The horizontal run-up action can improve the jumping height and obtain horizontal speed.When making contact with the vertical surface of the obstacle,the motion inertia in the horizontal direction can produce a reaction force on the contact surface,which can compensate for the influence of some gravity.This alternating contact strategy lets cats switch different initial and end contact angles.This investigation clarifies the essential process underlying animals’dynamic vertical wall climbing and establishes the theoretical foundation for the legged robot to do dynamic vertical wall climbing.

Optimal Center-of-Mass Pivot Effect of Spinal Motion in Feline Galloping

In this paper,we studied the acceleration behavior of a quadruped animal during a galloping motion.Because the development of many quadruped robotic systems has been focused on dynamic movements,it is obvious that guidance from the dynamic behavior of quadruped animals is needed for robotics engineers.To fulfill this demand,this paper deals with analysis of the galloping motions of a domestic cat,which is well known for its excellent acceleration performance among four-legged animals.Based on the planar motion capture environment,the movement data of a galloping feline was acquired and the dynamic motions were estimated using a spring-mass system.In particular,the effects of the position and angle of the center-of-mass of the cat,angular displacement of the spine,and angular velocity of the spine were analyzed and are discussed below.Through this process,it was possible to understand the dynamic movement characteristics of the cat,and to understand the relationships between,and the influences of,these parameters.From this analysis,we provide significant data applicable to the design of joint movements in quadruped robot systems.