Effect of heterologous seminal plasma and semen extenders on motility of frozen-thawed ram spermatozoa.

Ram seminal plasma increases the fertility of frozen-thawed ram spermatozoa deposited into the cervix. The aim of the current study was to compare the effect of ram seminal plasma to that of bull seminal plasma, dog prostatic fluid, protein-free TALP TrilEq (Triladyl with 0.5 mt of Equex STM paste added to each 100 mt) and heat-treated skim milk on longevity and percentages of progressively motile and aberrantly motile frozen-thawed ram spermatozoa. Three ejaculates from each of 6 rams were extended in TrilEq, pooled and frozen in straws as a single batch per ram. One hundred and eight straws (3 straws from each ram for each fluid) were thawed in random order. Once thawed, a straw was emptied into a tube with 0.85 ml of the appropriate fluid at 37 degrees C and kept at that temperature for 6 h. Motility was assessed at x200 magnification immediately (time zero) and 2, 4 and 6 h after thawing. Progressive motility decreased from each time to the next (P < 0.05) and was 39.0 % (0 h), 26.0 % (2 h), 19.6 % (4 h) and 12.6 % (6 h); SEM 1.24, n = 108 for each group. Ram seminal plasma resulted in higher progressive motility than bull seminal plasma, lower than milk, and similar to the other fluids. Ram seminal plasma resulted in lower aberrant motility than protein-free TALP and similar aberrant motility to other fluids. The effect of ram seminal plasma and dog prostatic fluid was very similar. The effect of ram seminal plasma on the fertility of frozen-thawed ram spermatozoa deposited into the cervix is not due an exceptionally beneficial effect on the motility of spermatozoa.

Birth of live calves by in vitro embryo production of slaughtered cows in a commercial herd in South Africa.

In vitro fertilisation (IVF) has become a useful breeding tool in most of the developed world. In this paper the success of bovine IVF and the birth of live calves under typical South African conditions is reported. Oocytes for IVF were collected from the ovaries of 6 slaughtered Bovelder beef cows. On average, 36.2 oocytes per donor were retrieved. From these oocytes, 43 blastocysts were produced from 5 of the donors by IVF with frozen Bovelder semen. The best 11 of these embryos were transferred into oestrous, synchronised Bovelder recipients in the same herd. As a result, 7 calves were born (a 64% calving rate) from 4 of the original donors. The calves had a normal birth mass, but the mean gestation length of the male calves was significantly longer than the herd average (291.6 versus 285.2 days respectively). No calving difficulties were encountered. In summary, it was shown that IVF for bovine embryo production and transfer is possible on a commercial basis in South Africa.

The effect of the laparoscopic insemination technique on the oestrous cycle of the ewe.

This investigation was designed to determine whether or not the technique of intrauterine insemination affects the length of the subsequent oestrous cycle. Dorper ewes (n = 31) were divided into treatment and control groups. All the ewes were synchronised using 40 mg fluorogestone acetate intravaginal sponges for 14 d and 300 IU pregnant mare serum gonadotrophin on the day of sponge removal. A standard semen diluent was deposited laparoscopically in each uterine horn of ewes in the treatment group. Teaser rams were used to detect oestrus. Progesterone profiles were used to confirm oestrus. The mean oestrous cycle length of 17.83 +/- 0.69 d for the group in which the diluent was deposited by laparoscopy did not differ significantly (P less than 0.1) from the 18.36 +/- 2.11 d of the control group. The technique of laparoscopic insemination did not influence the length of subsequent oestrous cycles.

Effect of heat stress on conception in a dairy herd model under South African conditions.

Three regression models are proposed for predicting reproduction in a model dairy herd under South African conditions. Conception rate (CR%) was related to mean monthly temperature-humidity index (THI) by; CR% = 31.15 THI - 0.25 THI(2) - 890.2, and first service conception rate (FSCR%) to THI by; FSCR% = 173.45 - 1.79 THI. Conception rate was related to numerical month of the year (M) by; CR% = 11.86 M - 0.82 M(2) + 26.36. The relation between mean monthly THI values and the conception rate of dairy cattle is significant. Further investigations to test the proposed regression models under various dairy herd conditions and to improve reproduction in South African dairy herds are needed.

Reduced mating efficiency due to osteo-arthrosis in a ram.

An apparently clinically normal ram with excellent semen quality, an intact pituitary-testicular axis and good libido displayed abnormal mounting behaviour when subjected to a mating test with 3 oestrus ewes. The ram adopted a peculiar mounting stance, he moved backwards several paces and then lunged forward becoming momentarily airborne in an attempt to mount. After a number of these airborne attempts at mounting the ram managed one successful service, striking the ewe with his sternum while airborne. At completion of the service the ram lost all sexual interest in the other two oestrous ewes. Radiographs revealed a chronic osteo-arthrosis of the right femero-tibial joint. It was concluded that the osteo-arthrosis caused the ram to suffer a great deal of pain interfering with his mounting ability which in turn affected his mating efficiency and serving capacity severely.