Proceedings of the New Zealand Society of Animal Production.
1992, 52: 179-182
Proceedings of the New Zealand Society of Animal Production.
1992, 52: 179-182
Twenty Romney ewes (n=10/group) received either 50mg bromocryptine (Parlodel LAÆ)/ewe, injected im every 4 weeks (B) or no treatment (C). Wool growth on mid-side patches (10 x 10 cm) and live weight were measured every 28 days for the duration of the 24 week study. Venous blood samples were collected for prolactin determination prior to treatment and at regular intervals during the investigation.
Plasma prolactin (mean ± SEM) was rapidly suppressed in treatment group B from a pre-treatment value of 118 ± 2 ng/ml to less than 12 ± 7 ng/ml. Prolactin levels in group C exhibited a gradual seasonal decline from 121 ± 3 ng/ml to 29 ± 2 ng/ml. A reduction in wool growth (g clean conditioned wool/100 cm¾/28days, mean ± SEM) was observed in both treatment groups in response to season, from 5.4 ± 0.4 g to 4.2 ± 0.4 g in group B and from 4.9 ± 0.5 g to 4.0 ± 0.5 g in group C; no significant (p<0.05) treatment effect was evident. Liveweight (mean ± SEM) of all animals increased from 50.8 ± 0.9 kg to 55.2 ± 0.8 kg during the study.
These results indicate that reduction and suppression of prolactin secretion commencing in late summer does not reduce wool growth in the Romney sheep.
Keywords: NZSAPAB; Wool growth; seasonality; prolactin; bromocryptine; sheep; Romney.
