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Hill country sheep production v. Occurrence of oestrus and ovulation rate of Romney and Border Leicester × Romney ewe hoggets
THERIOGENOLOGY
OVINE: Hight,
D.R. Lang and K.E. Jury. Hill country sheep production v. Occurrence of oestrus and ovulation rate of Romney and Border Leicester x Romney ewe hoggets. N-2. J. Agri. Res., 16:509. 1973. Whatawhata Hill Country Research Station, Mixstry of Agriculture and Fisheries, Private Bag, Hamilton, New Zealand. G.K.,
This study was part of a program to identify criteria which might give an early index of lifetime fertility. Data were obtained from 5 flocks including F of the crossbreds over 3 years. Livewe~~hf~'w~~~ %t',%a:~~~~ larly, and the ewes were first joined with rams in February when they were about 18 months old. Oestrus was not observed before the end of March and observations continued through to the last week in July: most activity was mid-May to mid-June. More crossbred hoggets exhibited oestrus. Differences were found in liveweights and weight gains after weaning between those which did and those which did not exhibit oestrus. Ovulation data, obtained by laparotomy, at first oestrus were significantly affected by flock and rank. The incidence of multiple ovulations was higher in crossbreds than Romneys and higher for single (heavier) than twin-reared hoggets. The results confirm that hoggets only exhibit oestrus if they have attained their threshold liveweight and age within the breeding season. Wide variation in ovulation rate was observed in the hoggets which began cycling, and this offers an opportunity for selection for increased fertility. However much work is required in order to differentiate between genetic and environmental effects in expression of oestrus and ovulation rate. D.R. Lamond.
S-K. Singh, A.R. Bhattacharya and S.N. Luktuke. Studies on biometry of genital organs of female goat. Indian Vet. J., 51:81. 1974. Indian Veterinary Research Institute,Isatnagar, U.P. India. India possesses more than 60 million goats. Goats are an important source of milk and meat in many parts of the world, yet studies concerning reproduction are few. As a first step at this Institute, the reproductive organs from 100 adult non-pregnant females were measured soon after slaughter. In general, they resembled a miniature form of bovine genitalia. Differences from the ewe were noted. D.R. Lamond.
FEBRUARY
1975
VOL. 3 NO. 2
91
OVINE: Hight,
D.R. Lang and K.E. Jury. Hill country sheep production v. Occurrence of oestrus and ovulation rate of Romney and Border Leicester x Romney ewe hoggets. N-2. J. Agri. Res., 16:509. 1973. Whatawhata Hill Country Research Station, Mixstry of Agriculture and Fisheries, Private Bag, Hamilton, New Zealand. G.K.,
This study was part of a program to identify criteria which might give an early index of lifetime fertility. Data were obtained from 5 flocks including F of the crossbreds over 3 years. Livewe~~hf~'w~~~ %t',%a:~~~~ larly, and the ewes were first joined with rams in February when they were about 18 months old. Oestrus was not observed before the end of March and observations continued through to the last week in July: most activity was mid-May to mid-June. More crossbred hoggets exhibited oestrus. Differences were found in liveweights and weight gains after weaning between those which did and those which did not exhibit oestrus. Ovulation data, obtained by laparotomy, at first oestrus were significantly affected by flock and rank. The incidence of multiple ovulations was higher in crossbreds than Romneys and higher for single (heavier) than twin-reared hoggets. The results confirm that hoggets only exhibit oestrus if they have attained their threshold liveweight and age within the breeding season. Wide variation in ovulation rate was observed in the hoggets which began cycling, and this offers an opportunity for selection for increased fertility. However much work is required in order to differentiate between genetic and environmental effects in expression of oestrus and ovulation rate. D.R. Lamond.
S-K. Singh, A.R. Bhattacharya and S.N. Luktuke. Studies on biometry of genital organs of female goat. Indian Vet. J., 51:81. 1974. Indian Veterinary Research Institute,Isatnagar, U.P. India. India possesses more than 60 million goats. Goats are an important source of milk and meat in many parts of the world, yet studies concerning reproduction are few. As a first step at this Institute, the reproductive organs from 100 adult non-pregnant females were measured soon after slaughter. In general, they resembled a miniature form of bovine genitalia. Differences from the ewe were noted. D.R. Lamond.
FEBRUARY
1975
VOL. 3 NO. 2
91