adult female shiba goats maintained at the tokyo university of agriculture and technology were used in this 
 study . six to eight goats were housed in a paddock with an outside area of 25 m , a sheltered area 
 of 15 m and a natural photoperiod . shiba goats are annual breeders in natural daylight conditions 
 in japan and have been used as an experimental model of ruminants . the goats were fed maintenance diets of 
 alfalfa hay cubes twice a day ( 0900 h and 1500 h ) . all the procedures were approved by the university committee for the use and care of 
 animals at tokyo university of agriculture and technology ( # 27 - 18 ) . all of the female goats were checked for 
 estrus once or twice daily and were considered to be in estrus when they allowed mounting by a male goat . we 
 tested 16 goats ( age = 29 years , body weight = 2137 kg ) that we confirmed as being in estrus ( n = 8) or not 
 in estrus ( n = 8) between december 2014 and january 2015 . an observation pen ( 2.5 m  2.5 m ) was set up in the 
 corner of the female paddock , with one side adjacent to the male paddock . a network camera ( dg - sf334 , 
 panasonic corporation , kadoma , japan ) was fixed to the ceiling . a captured image from the video recording data 
 is shown in fig . one male goat 
 was tied loosely with a rope to the adjacent side of the observation pen . a bright - colored circle marker ( red 
 or blue , 12 cm in diameter ) was attached to the back of female goats to enable identification and tracking in 
 video - recordings . the female goats were then moved gently into the observation pen by one observer ( the first 
 author of this paper : ne ) . the female and male goats were allowed to partially contact each other by poking 
 their snouts through the bars of the adjacent side of the observation pen . after an adaptation period of 
 approximately 10 min , the behaviors of the goats were recorded for 10 min using a network camera recorder 
 ( bb - hnp17 , panasonic ) connected to a personal computer . the computer was located in a building at a distance 
 from the goat paddocks . during video recordings , the observer remained in the building to prevent disturbing 
 the behaviors of the goats . after finishing video recording , behavioral observations were performed by a well - trained observer ( ne ) using 
 the video recordings . based on previous descriptions of sexual behaviors during estrus in goats , we investigated the occurrence of two behaviors as indicators of 
 proceptivity :  approaching the male  and  staying near the male . the following criteria were used to define 
 each behavior : approaching the male : walking or running from the other side of the observation pen toward the area adjacent 
 to the male paddock . staying near the male : staying or behaving restlessly in the area adjacent to the male paddock and 
 occasionally contacting with the male through the bars of the pen . the data frames were scored as 0 ( no behavior ) or 1 ( occurrence of a specific behavior ) to analyze each 
 behavior in terms of its frequency or duration . the video recordings were processed using the abdigitizer software ( chinou jouhou shisutemu , kyoto , japan ) . the positions and movements of the markers attached to the backs of the goats were tracked automatically , and 
 the x- and y - coordinates of the central point of the marker were outputted every 0.5 sec . based on the results of the human observations , the following criteria were employed to identify each 
 behavior from the video tracking data . the movement distance between two consecutive data points was 
 determined by calculating the euclidean distance , which represented the speed of movement ( cm/0.5 sec ) . standing : staying in one place and exhibiting no particular behavior . when the distance moved between two 
 consecutive data points ( corresponding to 0.5 sec ) was < 3 cm , the status was considered to be 
  standing . walking : when the distance moved between two consecutive data points was > 13 cm , the status was 
 considered to be  walking . the walking speed threshold ( 13 cm/0.5 sec ) was determined as the mean minus one 
 sd based on six control measurements from representative datasets . the range between 3 and 13 cm was used as 
 the buffer zone . approaching the male : when the distance from the male paddock ( corresponding to x - coordinate of the marker ) 
 decreased from > 120 cm to < 60 cm within nine consecutive data points ( corresponding to 4 sec ) , these criteria were based on the analysis of human 
 observation , in which a goat walked from the other side of the observation pen to the area adjacent to the 
 male paddock and the x - coordinate of the marker decreased from 120 cm to < 60 cm within nine consecutive 
 data points ( the mean plus sd based on six control measurements ) . staying near the male : when the x - coordinate of the marker was < 60 cm ( corresponding to the area adjacent 
 to the male paddock ) , the status was considered to be  staying near the male . all of the data were expressed as the mean  standard error ( se ) . parameters related to the behavioral 
 characteristics were analyzed using the student s t - test to compare the means between two 
 groups ( in estrus or not in estrus ) . the concordance 
 of the results obtained by video - tracking analysis and video - recorded observation by a human observer was 
 examined according to a previously described method . briefly , an 
 event was considered to be concordant if the behavior identified by video tracking analysis occurred within 
 the range of three time points before or after the time point recorded in human observations . the concordance 
 rate was calculated by dividing the number of concordant events ( true positive ) by the sum of the true 
 positives , false positives and false negatives . adult female shiba goats maintained at the tokyo university of agriculture and technology were used in this 
 study . six to eight goats were housed in a paddock with an outside area of 25 m , a sheltered area 
 of 15 m and a natural photoperiod . shiba goats are annual breeders in natural daylight conditions 
 in japan and have been used as an experimental model of ruminants . the goats were fed maintenance diets of 
 alfalfa hay cubes twice a day ( 0900 h and 1500 h ) . all the procedures were approved by the university committee for the use and care of 
 animals at tokyo university of agriculture and technology ( # 27 - 18 ) . all of the female goats were checked for 
 estrus once or twice daily and were considered to be in estrus when they allowed mounting by a male goat . we 
 tested 16 goats ( age = 29 years , body weight = 2137 kg ) that we confirmed as being in estrus ( n = 8) or not 
 in estrus ( n = 8) between december 2014 and january 2015 . an observation pen ( 2.5 m  2.5 m ) was set up in the 
 corner of the female paddock , with one side adjacent to the male paddock . a network camera ( dg - sf334 , 
 panasonic corporation , kadoma , japan ) was fixed to the ceiling . a captured image from the video recording data 
 is shown in fig . one male goat 
 was tied loosely with a rope to the adjacent side of the observation pen . a bright - colored circle marker ( red 
 or blue , 12 cm in diameter ) was attached to the back of female goats to enable identification and tracking in 
 video - recordings . the female goats were then moved gently into the observation pen by one observer ( the first 
 author of this paper : ne ) . the female and male goats were allowed to partially contact each other by poking 
 their snouts through the bars of the adjacent side of the observation pen . after an adaptation period of 
 approximately 10 min , the behaviors of the goats were recorded for 10 min using a network camera recorder 
 ( bb - hnp17 , panasonic ) connected to a personal computer . the computer was located in a building at a distance 
 from the goat paddocks . during video recordings , the observer remained in the building to prevent disturbing 
 the behaviors of the goats . after finishing video recording , behavioral observations were performed by a well - trained observer ( ne ) using 
 the video recordings . based on previous descriptions of sexual behaviors during estrus in goats , we investigated the occurrence of two behaviors as indicators of 
 proceptivity :  approaching the male  and  staying near the male . the following criteria were used to define 
 each behavior : approaching the male : walking or running from the other side of the observation pen toward the area adjacent 
 to the male paddock . staying near the male : staying or behaving restlessly in the area adjacent to the male paddock and 
 occasionally contacting with the male through the bars of the pen . the data frames were scored as 0 ( no behavior ) or 1 ( occurrence of a specific behavior ) to analyze each 
 behavior in terms of its frequency or duration . the video recordings were processed using the abdigitizer software ( chinou jouhou shisutemu , kyoto , japan ) . the positions and movements of the markers attached to the backs of the goats were tracked automatically , and 
 the x- and y - coordinates of the central point of the marker were outputted every 0.5 sec . based on the results of the human observations , the following criteria were employed to identify each 
 behavior from the video tracking data . the movement distance between two consecutive data points was 
 determined by calculating the euclidean distance , which represented the speed of movement ( cm/0.5 sec ) . standing : staying in one place and exhibiting no particular behavior . when the distance moved between two 
 consecutive data points ( corresponding to 0.5 sec ) was < 3 cm , the status was considered to be 
  standing . walking : when the distance moved between two consecutive data points was > 13 cm , the status was 
 considered to be  walking . the walking speed threshold ( 13 cm/0.5 sec ) was determined as the mean minus one 
 sd based on six control measurements from representative datasets . the range between 3 and 13 cm was used as 
 the buffer zone . approaching the male : when the distance from the male paddock ( corresponding to x - coordinate of the marker ) 
 decreased from > 120 cm to < 60 cm within nine consecutive data points ( corresponding to 4 sec ) , these criteria were based on the analysis of human 
 observation , in which a goat walked from the other side of the observation pen to the area adjacent to the 
 male paddock and the x - coordinate of the marker decreased from 120 cm to < 60 cm within nine consecutive 
 data points ( the mean plus sd based on six control measurements ) . staying near the male : when the x - coordinate of the marker was < 60 cm ( corresponding to the area adjacent 
 to the male paddock ) , the status was considered to be  staying near the male . all of the data were expressed as the mean  standard error ( se ) . parameters related to the behavioral 
 characteristics were analyzed using the student s t - test to compare the means between two 
 groups ( in estrus or not in estrus ) . the concordance 
 of the results obtained by video - tracking analysis and video - recorded observation by a human observer was 
 examined according to a previously described method . briefly , an 
 event was considered to be concordant if the behavior identified by video tracking analysis occurred within 
 the range of three time points before or after the time point recorded in human observations . the concordance 
 rate was calculated by dividing the number of concordant events ( true positive ) by the sum of the true 
 positives , false positives and false negatives .
here , we report a new method for measuring behavioral patterns during estrus in goats based on video 
 tracking analysis . 
 data were collected from cycling goats , which were in estrus ( n = 8) or not in estrus ( n = 
 8) . 
 an observation pen ( 2.5 m  2.5 m ) was set up in the corner of the female paddock with one side adjacent 
 to a male paddock . 
 the positions and movements of goats were tracked every 0.5 sec for 10 min by using a video 
 tracking software , and the trajectory data were used for the analysis . 
 there were no significant differences 
 in the durations of standing and walking or the total length of movement . 
 however , the number of approaches to 
 a male and the duration of staying near the male were higher in goats in estrus than in goats not in estrus . 
 the proposed evaluation method may be suitable for detailed monitoring of behavioral changes during estrus in 
 goats .