@conference {40560,
	title = {Timing single fixed-time inseminations in ewes: Some new concepts},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {54},
	year = {1994},
	month = {Jan},
	pages = {45-50},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The mean interval from the end of synchrony treatment to the onset of  
oestrus can be highly variable and as a consequence {\textquoteright}single-time{\textquoteright} inseminations  
may occur at other than optimal times.  This study was undertaken to identify  
some of the factors influencing the interval to oestrus following synchrony  
treatment, and to develop a spreadsheet model to assist with determining the  
timing of AI in ewes under a range of oestrous onset patterns.  Synchrony  
device, PMSG, time of year, and live weight tended to have important effects  
on the interval to oestrus.  Ewe genotype and year effects were generally small.   
Three new concepts have arisen from the modelling exercise.  Firstly, the actual  
timing of AI to achieve near maximum fertility depends on the mean interval to  
oestrus in a given flock, but not the precision of synchrony or the incidence of  
ewes that are synchronised.  Secondly, the {\textquoteright}tolerance{\textquoteright} about this optimum time  
of insemination depends on how much is known about the mean interval to  
onset (more information means more tolerance).  Thirdly, the {\textquoteright}tolerance{\textquoteright} about  
this optimum time of insemination depends on the maximum reduction in flock  
pregnancy rate that is acceptable to the flock owner (higher reduction means  
more tolerance).  If the onset pattern in a particular flock is unknown, the  
{\textquoteright}universal{\textquoteright} timing for a single fixed-time AI during the breeding season is 42- 
46 h after CIDR{\AE} removal, provided a drop in flock pregnancy rate of up to 5\%  
is acceptable. },
	issn = {1176-5283},
	author = {McMillan WH}
}
