Effect of insemination of estrus-induced prepuberal gilts on ensuing reproductive performance and body weight.

Prepuberal gilts reared and managed to 85-90 kg live weight in a common system were allocated at random to one of three first-mating treatments in an experiment conducted over a period of more than 5 years. In two of the treatments, gilts received a single i.m. injection of 400 IU equine chorionic gonadotropin (eCG) and 200 IU human chorionic gonadotropin (hCG) (PG600; Intervet) and were either inseminated 4 and 5 days later on a fixed-time basis regardless of oestrus (treatment A), or at the second oestrus following treatment (treatment B). The third group of gilts remained untreated and was inseminated on the first spontaneous oestrus (treatment C). Thereafter, all gilts were managed in the same way and those observed in oestrus were re-inseminated. Significantly more gilts returned to oestrus after the first service in treatment A (35%) than in treatment B and C (12 and 17%, respectively; P<0.01). Gilts farrowed to the first or repeat inseminations at a significantly younger age (P<0.01) in treatment A (304 days) than treatment B (324 days) and C (320 days). The age difference at farrowing remained in surviving gilts at the end of their third parity. The first farrowing performance of the gilts was significantly affected by treatment in terms of litter size at birth (A 7.0, B 8.4 and C 8.3 live piglets per gilt; P<0.01), litter size at weaning (A 6.2, B 7.2 and C 7.2 live piglets per gilt, P<0.05), and piglet birth weight (A 1.4, B 1.3 and C 1.3 kg; P<0.05) but piglet survival rate and weaning weight were not affected by treatment. The live weights of the gilts were significantly different between the treatments at first insemination (A 95.7, B 106.5 and C 109.2 kg; P<0.01) but not when the first litter was weaned (A 133.6, B 135.1 and C 136.6; P>0.05). After the first farrowing there were no differences between the treatments in terms of the survival rate, productive or reproductive performance of the gilts/sows and their offspring. Without conducting a detailed cost-benefit-calculation it was deduced that, from an economical point of view, differences between treatment A and treatments B and C are negligible because the savings associated with farrowing at a younger age on this treatment just about compensated for any additional costs associated with the treatment and the lower number of piglets born at the first farrowing.

Computer-assisted motility assessment of spermatozoa from fresh and frozen-thawed semen of the bull, boar and goat.

Generally, both subjective and computer-assisted (HTM-2000 motility analyzer) assessment of sperm motility in fresh and in frozen-thawed semen of bulls, boars and bucks yields comparable results. However, the use of a motility analyzer renders consistently more accurate estimates, especially when that motility is vigorous as in fresh bull semen.

Control of prostaglandin-induced parturition in sows by injection of the beta-adrenergic blocking agent carazolol or carazolol and oxytocin.

Although parturition commonly is induced in swine with prostaglandin F2 alpha or one of its analogs, variation in response to the treatment is large. The purpose of this investigation was to more precisely terminate parturition. Two experiments were conducted. Sows all received prostaglandin analog followed, 20 h later, by different doses of the beta-adrenergic blocking agent carazolol and(or) oxytocin. Treatment with 3 mg of carazolol alone caused parturition to commence within 2.6 +/- .23 (SEM) h after injection. Parturition was complete in 2.0 +/- .13 h and proceeded smoothly without the necessity of manual assistance. Adding 2.5 I.U. of oxytocin to the 3 mg of carazolol speeded the onset of labor (1.7 +/- .17 h). However, in some cases parturition was interrupted and the time passing between the birth of the first and the last piglet was prolonged to 2.5 +/- .28 h. We conclude that by applying carazolol 20 h after a prostaglandin analog, parturition in swine may be terminated very effectively.

Deep - freezing of rainbow trout Salmo gairdneri sperm at varying intervals after collection.

Rainbow trout semen cryopreserved 0.33, 5, 60 and 360 min after collection gave postthaw fertilization rates of 71.9, 68.4, 65.5 and 49.1% of eyed eggs, respectively. The corresponding result obtained with chilled semen stored for 2 wk under oxygen was 96.9%. This suggests that the freezing of rainbow trout semen should be done immediately after collection.