RESUMEN
Microscopically evaluated sperm parameters, as well as computer-aided sperm motility analysis (CASMA), were used to assess sperm quality and the effect of cryopreservation on ram semen obtained from two genetically diverse Merino lines. These lines were divergently selected on maternal ranking values for multiple rearing ability from the same base population since 1986. Replacements in the high (+) line were preferentially the progeny of ewes rearing >1 lamb per joining. Progeny of ewes rearing <1 lamb per joining was preferred as replacements in the low (-) line. Sperm quality, as assessed by percentages of live, abnormal and acrosome-intact spermatozoa as well as by motility, was independent (P < or = 0.20) of line, time of sampling and their interaction in ejaculated samples obtained from the eight rams used as sires in 1995. Sperm quality of frozen-thawed samples was adversely affected (P < or = 0.01) by cryopreservation and thawing at 35 degrees C for 30 s relative to fresh ejaculated samples. No consistent differences between lines were found in epididymal sperm samples obtained from 12 slaughtered rams (6 from each line). The adverse effect (P < or = 0.05) of cryopreservation and thawing at 35 degrees C for 30 s on sperm viability and motility was also demonstrated for these samples.
Asunto(s)
Criopreservación , Preservación de Semen , Ovinos/genética , Espermatozoides/fisiología , Animales , Supervivencia Celular , Eyaculación , Epidídimo/citología , Femenino , Masculino , Semen , Conducta Sexual Animal , Especificidad de la Especie , Motilidad Espermática , Espermatozoides/citologíaRESUMEN
The effect of cryopreservation on the viability and motility of epididymal African buffalo spermatozoa was studied in samples obtained from 17 and 13 animals in 1995 and 1996, respectively. Cryopreservation significantly reduced the viability and motility of the epididymal spermatozoa. The average percentage of live (+/- SE) spermatozoa declined significantly from 90.4 +/- 2.0% (1995) and 84.4 +/- 1.1% (1996) in fresh epididymal samples, to 57.0 +/- 2.0% and 56.3 +/- 1.1%, respectively, in frozen-thawed samples. The acrosomal integrity (+/- SE) of spermatozoa declined from 89.3 +/- 2.3% (1995) and 93.3 +/- 2.2% (1996) to 50.2 +/- 2.3% and 37.5 +/- 2.2%, respectively. In 1995, this effect was largely associated with the thermal equilibration prior to cryopreservation.
Asunto(s)
Búfalos , Criopreservación/veterinaria , Preservación de Semen/veterinaria , Motilidad Espermática , Espermatozoides/citología , Acrosoma/ultraestructura , Animales , Epidídimo , Masculino , Preservación de Semen/métodos , Espermatozoides/fisiologíaRESUMEN
The effect of a slow-releasing oxytocin preparation on the ovulation rate of Merino ewes was investigated. Synchronised Merino ewes were subcutaneously injected with a slow-releasing preparation containing 10 IU oxytocin, 48 hours after sponge withdrawal. Laparoscopic examination of the ovaries of all ewes was performed 10 d after the oxytocin treatment in order to determine the number of corpora lutea per ewe. The ovulation rate of the adult ewes of the treated and control groups was 179.1% and 159.1% respectively (p < 0.05) while that of the 2-tooth ewes was 108.3% and 112.8% respectively (p > 0.05). It would appear that a higher ovulation rate can be obtained by a single injection of a slow-releasing oxytocin preparation at the onset of oestrus. The lack of response in the 2-tooth ewes was probably due to their relatively low body weight.
Asunto(s)
Estro , Inducción de la Ovulación/veterinaria , Ovulación/efectos de los fármacos , Oxitocina/administración & dosificación , Ovinos/fisiología , Animales , Preparaciones de Acción Retardada , Femenino , Inducción de la Ovulación/métodosRESUMEN
The effect of oxytocin treatment on the ovulation rate of Merino ewes was investigated. Intravenous doses (0.1 IU) of oxytocin were administered to synchronised ewes (n = 54) every 30 min for a 24 h period beginning at the onset of oestrus. Laparoscopic examination of the ovaries of all ewes that had displayed overt oestrus following sponge withdrawal was performed 10 d after the beginning of oxytocin treatment to determine the number of corpora lutea per ewe. The ovulation rates of the treated and control groups were 174.5% and 144%, respectively (p < 0.01). It would appear that a higher ovulation rate can be obtained by repeated low-dose intravenous injection of oxytocin during oestrus.
Asunto(s)
Estro/efectos de los fármacos , Ovulación/efectos de los fármacos , Oxitocina/farmacología , Ovinos/fisiología , Animales , FemeninoRESUMEN
The toxicity of 2 parenteral copper (Cu) supplements was investigated. Di-sodium copper ethylene diamino tetra acetate (Cu EDTA) and Cu heptonate were administered to sheep (n = 9) by a single subcutaneous injection at a concentration of 0,2, 1 and 2 mg Cu/kg each (Trial 1.) Nine sheep were untreated and served as controls. The same treatments were applied to 2 sheep each (Trial 2) with the addition of 3 mg Cu/kg live body mass as Cu heptonate, and Cu heptonate administered intravenously at rates of 0,2, 0,4 and 0,6 mg Cu/kg live body mass. In Trial 1, 67% of the sheep treated with Cu EDTA at 2 mg Cu/kg live body mass died within 3 to 17 d after treatment, while no mortalities occurred in sheep where Cu heptonate was administered at the same dosage rate and even at 3 mg Cu/kg live body mass (P < or = 0,01). Post-mortem examination suggested acute Cu toxicity in all cases. Liver Cu concentrations were markedly increased (P < or = 0,05) by both supplements in groups of 3 treated sheep slaughtered over a 3-month period compared to control animals. The liver Cu concentrations of sheep that succumbed to Cu toxicity were within the normal range of 100 to 450 mg/kg DM. Results from Trial 2 suggested that the 2 sheep treated with 2 mg Cu/kg live body mass as Cu EDTA, experienced a haemolytic crisis between 5 and 11 d after treatment, resulting in the death of one of these sheep. The haemolytic crisis was characterised by a severe decrease in haemoglobin concentration and haematocrit.(ABSTRACT TRUNCATED AT 250 WORDS)