Concentration of melatonin in plasma of goats treated with
Regulin
A.L. Parry, D.J. Paterson, A.J. Litherland, A.F. Death, L.D.
Staples
MAF Technology, Flock House Agricultural Centre, Bulls, New
Zealand
Proceedings of the New Zealand Society of Animal Production.
1990, 50: 297-300
The duration of melatonin release from Regulin implants and the
diurnal variation in plasma melatonin concentration was investigated in
18 cashmere wethers, divided into 3 treatments: C-control; T-treated
with melatonin 18mg Regulin implant on 10.11.88; PT - previously treated
with melatonin every 6 weeks for 10 months before receiving an implant
on 10.11.88. Mean concentration of plasma melatonin in T remained high
52 pg/ml for up to 42 days after implant, then declined to 8.5 pg/ml at
50 days remaining relatively low for the rest of the sampling period.
Goats from PT maintained much high concentration of plasma melatonin 226
pg/ml for 42 days after implant. Control goats showed very low mean
concentration at 5 pg/ml. Between animal variation in plasma melatonin
concentration was high coefficients of variation were between 100% and
200% within all treatments.
At 8 days post-implant plasma melatonin concentration of goats in C
showed a nocturnal increase averaging 12.5 pg/ml, between sunset and
sunrise. The same diurnal fluctations were evident at 29 days post-
implant. Goats in treatment T also showed a nocturnal rise in plasma
melatonin concentrations with average increases of 15 and 24 pg/ml at 8
and 29 days post implant between sunset and sunrise.
It can be concluded that the melatonin implants used in this trial
lasted for 42 days after administration and a nocturnal rise in
melatonin concentration was evident in control and treated goats.
Keywords: NZSAPAB;
Melatonin; goats; blood levels; plasma
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