@conference {41841,
	title = {Zearalenone challenge in sheep : urine sampling to measure response},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {316-319},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Zearalenone is a fungal toxin produced by Fusarium species commonly found on autumn pastures in New Zealand. It may interfere with reproductive functions in sheep. In a search for a genetic measure of susceptibility, ewe and ram lambs were dosed orally with a suspension of zearalenone at a series of rates, at 8 and 11 months of age. Urine samples were taken at intervals from 2 to 50 hours later. The concentration of urinary zearalenone and its metabolites (Zen) was assayed using an ELISA. Adjustment for urinary volume was made by measuring the urinary concentration of creatinine (Cr), and results were expressed as Zen/Cr ratio (loge-transformed). In a separate experiment, breeding ewes were dosed with zearalenone at a single rate, and Zen/Cr response was measured. The following effects were evaluated in lambs: a) sex difference (ewe versus ram lambs), b) responses to three dose rates, c) time-series response data. The heritability of Zen/Cr was determined in lambs and breeding ewes; results were analysed after standardising for each treatment and sampling group. Urinary Zen/Cr, 6 h after dosing, differed between ewe and ram lambs by a factor of 1.75 (ewe lambs higher; P < 0.01). Zen/Cr values for three dose rates (3, 6 and 9 mg zearalenone per lamb), averaged over three sampling time points after dosing, were 23.5, 43.2 and 59.3, respectively (P < 0.0001). Zen/Cr values for three sampling time points (2, 4 and 6 h after dosing), averaged over three dose rates, were 58.0, 35.8 and 29.0, respectively (P < 0.0001). By 50 h after dosing, the Zen/Cr average had fallen to 4\% of its 2-h value. The interaction between dose rate and time of urinary sampling was not significant for log Zen/Cr. A preliminary estimate of the heritability for standardised Zen/Cr was 0.32 {\textpm} 0.10 (P < 0.01). The dosing regime reported here could be used for a test of animal response to zearalenone in ram breeders{\textquoteright} flocks.
KEYWORDS: sheep; zearalenone; dose response; urine; heritability. },
	issn = {1176-5283},
	author = {Morris CA and Amyes NC and Sprosen JM and Hawkes AD and Finch SC and Miles CO}
}
@conference {41842,
	title = {Zearalenone challenge in sheep : variation in ovulation rate},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {320-323},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Zearalenone is a fungal toxin produced by Fusarium species commonly found on autumn pastures in New Zealand, and it may interfere with reproductive functions in sheep. We have measured both ovulation rate after challenge with zearalenone, and also a metabolic indicator, Zen/Cr (the concentration of zearalenone and its breakdown products (Zen) in urine, after adjustment for urinary volume using creatinine concentration (Cr)). A small self-replacing flock of Coopworth ewes was used for the study. This paper reports a preliminary assessment of whether Zen/Cr might be an equivalent but cheaper method than laparoscopic ovulation rate for measuring an animal{\textquoteleft}s resistance to zearalenone. Ovulation rates were determined in ewes in autumn before dosing (Lap1; Years 1 and 2), and after dosing (Lap2; Years 1 to 4) with 10 mg zearalenone per animal per day for 6 days. The average reduction in ovulation rate following dosing (Years 1 and 2: Lap1 minus Lap2) was 0.60 ovulations or 31\% of the mean. Lap2 was used for the present correlation analyses. The heritability of Lap2 was estimated (0.11 {\textpm} 0.09), and breeding values (BVs) for Lap2 were determined. Subsequent to the laparoscopy, the ewes were mated at pasture, and the resulting natural litter sizes were monitored in relation to BVs for ovulation rate after challenge. Urine samples were taken during and after dosing in Years 3 and 4, to measure Zen/Cr, and a heritability for Zen/Cr (0.32 {\textpm} 0.10) was estimated from these and other Zen/Cr data. Preliminary analyses of BVs for Lap2 and Zen/Cr revealed a negative correlation between them (r = - 0.55). Ewes with higher BVs for ovulation rate also had higher mean litter sizes following natural ovulation. In conclusion, zearalenone affects ovulation rate at moderate challenge levels, and this ovulation rate may be negatively related to the concentration of measurable urinary zearalenone metabolites.
KEYWORDS: sheep; zearalenone; dose rate; ovulation; heritability. },
	issn = {1176-5283},
	author = {Morris CA and Amyes NC and Smith JF and Sprosen JM and Towers NR}
}
@conference {40923,
	title = {Free and conjugated levels of zearalenone in ewes mated on grass dominant pasture or chicory.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {190},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Zearalenone is an oestrogenic mycotoxin commonly found in New Zealand pastures (di Menna, and et al., 1987). Ingestion of zearalenone by sheep causes reductions in reproductive performance (Smith, and et al.,1990). It is likely that high zearalenone concentrations in pasture around mating will often be sufficient to affect reproductive per-formance of the ewe. Chicory pastures contain very low zearalenone concentrations and therefore have potential as a feed for ewes prior to and during mating. The aim of this trial was to determine the levels of free and conjugated zearalenone in the blood and urine of ewes grazed on either grass-dominant pasture or chicory prior to and during the mating period, and assess any subsequent effects on reproductive performance.},
	issn = {1176-5283},
	author = {Kramer R and Keogh RG and Sprosen JM and McDonald MF}
}
