@conference {40993,
	title = {Factors influencing the prevalence of postpartum anoestrus in New Zealand dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {79-81},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The aim of this study was to determine the association between age, interval from calving (PPI) and breeding worth (BW) and prevalence of postpartum anoestrus (AA), as well their effect on response to hormonal treatment by anoestrous dairy cows. Individual cow details were collated from 6649 cycling and 2446 AA animals in 29 herds. Probability of AA was influenced by herd and was negatively related to PPI and age (p<0.001); but was not related to BW (p>0.05). Response of AA cows to treatment with progesterone and oestradiol benzoate was evaluated using a subset of 1482 anoestrous cows. Within 7 days of treatment, oestrus was detected in 87.1\% cows and conception rate to insemination during this period was 42.2\%. Oestrous response varied between herds but was not influenced by BW, PPI or age (p>0.1). Conception rate was positively related to PPI (p<0.001), but was not influenced by BW or age (p>0.1). It is concluded that in commercial dairy herds the likelihood of a cow being AA is greatest in young and recently calved animals, but is not influenced by breeding worth.},
	issn = {1176-5283},
	author = {Rhodes FM and Clark BA and Nation DP and Taufa VK and Macmillan KL and Day ML and Day AM and McDougall S}
}
@conference {40944,
	title = {Effect of hormonal environment at emergence on persistence of ovarian follicles in cattle},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {239-240},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Reduced fertility often occurs when progestins are used to control the timing of oestrus in cattle and is espe-cially evident when a corpus luteum (CL) is not present in the ovary (Kinder et al., 1996). The lowered conception rates at the synchronised oestrus are associated with the development of abnormally large, {\textquotedblleft}persistent{\textquotedblright} ovarian fol-licles as a result of increased secretion of LH. An under-standing of the endocrine regulation of persistent follicles is essential for development of methods to prevent ovula-tion of this aberrant structure in progestin-based oestrous control systems. The influence of time of luteal regression relative to follicle emergence on persistence of dominant follicles was evaluated in progestin-treated cows.},
	issn = {1176-5283},
	author = {Day ML and Burke CR and Nation DP and Rhodes FM and Macmillan KL}
}
