A note on breeding the nilgai Boselaphus tragocamelus at Stanley Zoo

BREEDING A note on breeding the nilgai at Stanley Zoo Boselaphus rragocamelus M. W. L A C E Y Curator, Stanley Park Zoo, Co. Durham, Great Britain The male nilgai Boselaphus tragocamelus arrived at Stanley Zoo on 17 June 1966 at the age of about two years. The female arrived on 25 June 1966 and was slightly larger than the male, being about three years old. Both animals were housed in a half-acre paddock, containing a shelter measuring 3 by 6 m . Although very nervous, they settled down well and readily ate a diet of best quality meadow hay and good quality clover hay ad lib. In addition, each animal received 2.7 kg of Ungulate Mix (sheep and lamb nuts, summer milk nuts, best quality rolled oats, flaked maize, linseed cake and bran), 1.8 kg chopped cabbage, 1.3 kg of carrots and 6 bananas with their skins on daily. Twice weekly they were fed branches of willow, oak or birch leaves. A salt lick, containing cobalt, copper, manganese and iron in iodised salt was always available. 56 g vitamin supplement was sprinkled on the bananas for each animal daily. Both animals were treated with the anthelmintic Thibenzole on arrival at the zoo. The female first showed signs of being in oestrus on 2 August 1966 and remained so for about four days. During this period she called frequently, though normally she is a quiet animal. Mating was never observed, but it must have occurred during the late evening or night of the four days of oestrus. She was not seen to come into oestrus again. Both nilgai were kept outdoors all the winter of 1966-67, without any heat, although the tem- perature fell below freezing point most nights. A paraffin heater was placed under the water con- tainer at night. During the winter each animal received an additional 0.9 kg of Ungulate Mix. At the beginning of 1967 it became obvious that the female was pregnant. She was again treated with Thibenzole to prevent worm infesta- tion after calving. Two weeks before the birth the female’s udder started to swell. Three days before calving the udder was the size of a small domestic heifer’s and was larger than we expected to find on an antelope the size of the nilgai. Milk was noticed in the udder on the afternoon of 12 April, and the twin young, one male and one female, were born on the afternoon of 13 April, after a gestation period of 250 days. This agrees with an average gestation period of 247 days given by Jennison (1927). For the first 10 days the calves hardly ever ventured outside their shed, spending most of their time sleeping in separate corners. They seldom slept together during the day. The only time they were seen standing was when they were suckling, which they did simultaneously at two- hourly intervals. The young were suckled in full view of the visitors and did not seem to be disturbed by their presence, although the female became aggressive with her keeper and me whenever we entered her paddock, making mock charges at us. The male did not share the protec- tive role and spent most of the day grazing in the paddock, completely indifferent to the calves. R E F E R E N C E JENNISON, G . (1927): Table of gestation periods and number of young. London: A. & C. Black, Ltd. Manuscript received M a y 1967