Amine-organic buffers (BESKOH and TESTRIS) were compared for their ability to be used for buck semen dilution in a freezing procedure. BESKOH showed better results (P < 0·05) at the time of dilution and after chilling at +5°C (72% motility v. 54% at dilution and 62% v. 39% after chilling). After freezing and thawing, none of the variables measured (motility, normal acrosome ridge and normal swelling) was significantly different. A washing procedure was necessary when freezing was undertaken and egg yolk addition was necessary to avoid cold shock as the temperature lowered during chilling. There were no significant differences between a 3% and 12% level of egg yolk addition.

Fresh sperm motility declined from 79·2 (s.e. 0·9)% to 55·8 (s.e. 1·7)% while occurrence of normal acrosomes declined from 82·9 (s.e. 1·3)% to 71·3 (s.e. 1·2) % from the day of collection to 7 days after collection, and conception rate declined from 47·6% using 3-day-old semen to less than 30% from using 5· or 7-day-old semen. Neither the number of embryos nor embryo survival from pregnant sows were affected by the age of semen. Boar effects were evident but they did not interact with the effects of age of semen, indicating that semen quality after storage was proportional to initial semen quality.

Six experiments involving the artificial insemination (AI) of a total of 300 female red deer (hinds) with frozen-thawed red deer semen (collected by electro-ejaculation) were conducted over 3 years. Insemination took place at fixed times following various oestrous synchronization procedures using progesterone withdrawal and treatment with pregnant mare's serum gonadotropin (PMSG). In the 1st year, the experiments evaluated basic AI techniques in which pregnancy rates were 45% in 20 hinds receiving two inseminations per vaginam (PV) and 56% in 27 hinds inseminated by the laparoscopic intrauterine method (IU). In the 2nd year, the experiments involved comparisons of the progesterone regime, one or two PV inseminations, and the timing of a single PV insemination. There was no effect of replacement of the progesterone device after 9 days and withdrawal 3 days later compared with the use of one device for the whole period in two experiments. The pregnancy rate for a double PV insemination was significantly higher than for a single PV insemination (58 and 34%; P < 0·05) and there was also a small effect of timing of insemination relative to the synchronization treatment. In the 3rd year all hinds were inseminated by the IU method. The experiments involved a comparison of various times of AI following progesterone withdrawal and a comparison of the progesterone regime. The overall pregnancy rate for 63 hinds inseminated was 56% with no difference between three times of insemination (48, 52 and 55 h). In the second experiment, the difference in pregnancy rate between treatment with progesterone for 15 days and 12 days (44 and 72% for 18 hinds per group) was not significant, but the interaction between the length of progesterone treatment and insemination time was significant (P < 0·05), with the 12-day progesterone/55 h insemination giving a much higher pregnancy rate than the 15-day/55 h insemination (89 and 20% respectively). Although no experiments involved direct comparisons of the routes of insemination, overall pregnancy rates were 56% for IU, 53% for double PV and 35% for single PV inseminations.