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The effect of bovine pestivirus on ovulation in superovulated friesian heifers
317
Theriogenology
Superovulation THE EFFECT
OF BOVINE
M. Kafi’, M.R. McGowan’, ‘Department
PESTIVIRUS ON OVULATION FRIESIAN HEIFERS D. Jillella’, D. Fenwick’,
of Farm Animal Medicine & Production, Brisbane 4072, Australia. ‘Elizabeth Macarthur Agr. Inst., Menangle,
IN
SUPEROVULATED
S. Johnston’, University
P.D.Kirkland* of Queensland.
NSW, Australia.
It has been observed that cattle infected with bovine pestivirus during superovulation yielded significantly lower numbers of ova/embryos (Kafi et al. Theriogenology 41: 223). An experiment was designed to determine the pattern of follicular development in superovulated cattle infected with pestivirus during the pre- and periovulatory period. Twenty-five cycling Friesian heifers, seronegative to pestivirus, were randomly assigned to either a control group (C, n=12) which did not become infected, or a treatment group (I, n=l3) which became infected following intranasal inoculation with bovine pestivirus (5.5 log,, TCID,,/ml) 9 days before AI. On day 10 f 2 of the estrous cycle, animals were superovulated with a series of FSH-P (total dose 30 mg, Schering Corp. USA) injections twice daily over a 4 day period. Animals received an injection of prostaglandin F2a (Lutalyse, 25 mg) 48h after the first FSH-P injection. The heifers were inseminated at 12 and 24h after the onset of estrus with pestivirus free frozen-thawed semen. Follicular development was monitored daily by transrectal ultrasonography beginning one day before the commencement of superovulation until day 3 after oestrus. Follicles were grouped into three diameter classes: < 5mm, 5 to 8mm and 2 9mm. Also, the diameter of the presumptive ovulatory follicles (29mm) on the day of AI were measured. Ovulation was confirmed by the disappearance of the presumptive ovulatory follicles. Data were analysed using repeated measures ANOVA and x2 test a g I;’ where appropriate. : There was no significant ‘iis 1 difference between the two groups in the Z mean number of the follicles within each -4 size category during the period of 2 62 gonadotrophin stimulation. However, tZ there was a trend towards a lower number 0 I of ovulatory size follicles in the infected 1 -1 AI animals (Fig. 1). Also, there was no Dan
significant difference between the 2 Fig. 1. Yean (aaam)Vnumbar of orulatorJ sire folliolsm on the dap before, during groups in the diameter of presumptive and after AI. ovulatory follicles on the day of AI. At 24h after the first AI, 82 per cent of the presumptive ovulatory follicles had ovulated in the control group while in the pestivirus infected animals, only 17 per cent of ovulatory size follicles had ovulated (P
Theriogenology
Superovulation THE EFFECT
OF BOVINE
M. Kafi’, M.R. McGowan’, ‘Department
PESTIVIRUS ON OVULATION FRIESIAN HEIFERS D. Jillella’, D. Fenwick’,
of Farm Animal Medicine & Production, Brisbane 4072, Australia. ‘Elizabeth Macarthur Agr. Inst., Menangle,
IN
SUPEROVULATED
S. Johnston’, University
P.D.Kirkland* of Queensland.
NSW, Australia.
It has been observed that cattle infected with bovine pestivirus during superovulation yielded significantly lower numbers of ova/embryos (Kafi et al. Theriogenology 41: 223). An experiment was designed to determine the pattern of follicular development in superovulated cattle infected with pestivirus during the pre- and periovulatory period. Twenty-five cycling Friesian heifers, seronegative to pestivirus, were randomly assigned to either a control group (C, n=12) which did not become infected, or a treatment group (I, n=l3) which became infected following intranasal inoculation with bovine pestivirus (5.5 log,, TCID,,/ml) 9 days before AI. On day 10 f 2 of the estrous cycle, animals were superovulated with a series of FSH-P (total dose 30 mg, Schering Corp. USA) injections twice daily over a 4 day period. Animals received an injection of prostaglandin F2a (Lutalyse, 25 mg) 48h after the first FSH-P injection. The heifers were inseminated at 12 and 24h after the onset of estrus with pestivirus free frozen-thawed semen. Follicular development was monitored daily by transrectal ultrasonography beginning one day before the commencement of superovulation until day 3 after oestrus. Follicles were grouped into three diameter classes: < 5mm, 5 to 8mm and 2 9mm. Also, the diameter of the presumptive ovulatory follicles (29mm) on the day of AI were measured. Ovulation was confirmed by the disappearance of the presumptive ovulatory follicles. Data were analysed using repeated measures ANOVA and x2 test a g I;’ where appropriate. : There was no significant ‘iis 1 difference between the two groups in the Z mean number of the follicles within each -4 size category during the period of 2 62 gonadotrophin stimulation. However, tZ there was a trend towards a lower number 0 I of ovulatory size follicles in the infected 1 -1 AI animals (Fig. 1). Also, there was no Dan
significant difference between the 2 Fig. 1. Yean (aaam)Vnumbar of orulatorJ sire folliolsm on the dap before, during groups in the diameter of presumptive and after AI. ovulatory follicles on the day of AI. At 24h after the first AI, 82 per cent of the presumptive ovulatory follicles had ovulated in the control group while in the pestivirus infected animals, only 17 per cent of ovulatory size follicles had ovulated (P