@conference {40608,
	title = {Hormonal and ovarian responses in Romney ewe hoggets after synchronisation and superovulation treatment.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {54},
	year = {1994},
	month = {Jan},
	pages = {239-242},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Twelve, 10-month old ewe hoggets (Av LW 32.5 kg) were placed in  
metabolism crates under controlled lighting (11 h L:13 h D) for a 9 d  
adaptation period and were fed for maintenance.  They were synchronized by  
vaginal insertion of CIDR and treated with gonadotrophins for superovulation.   
Of the 12 hoggets 9 had two or more successive plasma samples with > 0.9  
ng/ml progesterone (P4) indicating they had ovarian activity prior to treatment.   
Mean P4 concentrations prior to treatment (d - 3) were 0.69 {\textpm} 0.18 ng/ml and  
had risen to 1.50 ({\textpm} 0.38), 1.72 ({\textpm}0.35), 1.36 ({\textpm}0.11) and 1.31 ({\textpm}0.10) ng/ml  
for d 0 to d 3 of treatment.  On d 9, 10 and 11, prior to CIDR removal, P4 levels  
were back to base line levels (0.60, 0.46 and 0.57 ({\textpm}0.06) ng/ml respectively).   
The mean number of follicles and corpora lutea were 5.0 ({\textpm}0.95) and 1.8  
({\textpm}0.53), respectively.  Total CL had a negative correlation (r = -0.64, P<0.05)  
with the P4 concentration on the day of CIDR removal.  Six of the 12 ewes had  
an LH peak within 25 hours after CIDR removal.  In addition, those ewes  
treated during late cycle tended (P>0.10) to have a better ovarian response than  
those treated at early or mid cycle.  These results suggest it may be necessary  
to use two CIDR to maintain a sufficiently long period of P4 elevation. In  
addition, the day of the cycle that the CIDR is inserted may be important to  
achieve maximum response from ovulation enhancement treatment in ewe  
hoggets. },
	issn = {1176-5283},
	author = {Campbell JW and McDonald MF and Wickham GA}
}
