@conference {41125,
	title = {Effect of very low sperm doses on pregnancy rates after AI in sheep.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {219-222},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Low sperm numbers and ambient temperature storage are two important factors in the successful AI system for dairy cattle in New Zealand. A critical evaluation of these factors with ram semen is required before the establishment of a similar AI system within the NZ sheep industry is feasible. A trial involving a total of 1262 Romney ewes was conducted in April 1998 to examine the effects of inseminate dose (25, 5, 1 and 0.5 x 106 sperm) of semen held for up to 9 h at 20{\textdegree}C in two diluents (RSD-1 and RSD-8). Ewes, synchronised with 3 types of CIDR devices were laparoscopically AI{\textquoteleft}ed with semen from either a Finn or a Romney ram at set times (49 or 56h) after CIDR removal. AI was spread over 4 days in each of two consecutive weeks. Rams were used on each alternative day. Ewes were checked for return to service to determine pregnancy. There was a significant (P<0.001) difference between rams in pregnancy rate (Finn =35.6 and Romney =52.5\%). There was an effect (P<0.001) of inseminate dose (25 = 55.5 {\textpm} 2.6\%; 5 = 45.2 {\textpm} 2.6\%; 1 = 37.2 {\textpm} 2.6\% and 0.5 = 37.5 {\textpm} 2.6\%). However there was a suggestion of an overall dose by ram interaction with the Romney semen maintaining higher fertility at lower dose levels. There were no effects of inseminator or of diluent. Time from CIDR removal to oestrus had a significant (P<0.05) effect. Time to onset of oestrus was affected by CIDR type. While there was no overall effect of CIDR type on fertility, there was a significant (P<0.05) interaction between sperm dose and CIDR type. These results indicate that acceptable (>50\%) fertility can be achieved with sperm dose rates as low as 1.0x106 if semen quality is satisfactory thus increasing the number of inseminates per ejaculate 20-50 fold. Improved synchrony methods seem imperative to obtaining better fertility from AI. },
	issn = {1176-5283},
	author = {Smith JF and Parr J and Murray GR and Clarke A and Oliver JE and McDonald RM and Duganzich DM}
}
@conference {41023,
	title = {Effect of sperm dose, diluent type and timing of insemination on pregnancy rates in sheep.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {186-188},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Low sperm numbers and ambient temperature storage are two important factors in the successful AI system for dairy cattle in New Zealand. Similar technologies with ram semen are required before the establishment of a similar AI system within the NZ sheep industry is feasible. A trial involving a total of 1200 Romney ewes was conducted in April 1997 to examine the effects of inseminate dose (50, 25, or 5 x 10--6 sperm) of semen held for up to 9 h at 20{\textdegree}C in two diluents (RSD-1 and Tris + egg yolk). In the first half of the trial ewes were laparoscopically inseminated with semen from Finn rams at set times (49 and 56 h) after CIDR removal, while in the second half of the trial ewes were inseminated with semen from Romney rams following the detection of oestrus, after CIDR removal, resulting in insemination times of 26, 44 and 49 h post removal. Returns to service in the cycle following AI were recorded and ewes were scanned for pregnancy 50 days post AI. There was a significant difference between ram breeds in pregnancy rate (Finn 63.2 \% v Romney 50.2 \% ; P<0.05). There were no effects of inseminate dose nor of diluent. Time to onset of oestrus was affected by ewe live weight (P<0.05) with the heavier ewes showing a trend for an earlier onset but there was no overall effect of ewe weight on fertility. The effect of time to onset was reflected in an effect of time from CIDR removal to AI in the second half of the trial, with ewes AI{\textquoteright}d within 30h of CIDR removal having a 10\% lower fertility. These results indicate that acceptable fertility can be achieved with semen dose rates 5 to 10 fold less than normal, thereby increasing the number of inseminations available per ejaculate. Improved synchrony methods seem imperative to obtaining better fertility from AI. },
	issn = {1176-5283},
	author = {Smith JF and Parr J and Murray GR and Clarke A and Oliver JE and Duganzich DM}
}
@conference {41022,
	title = {Relationships between laboratory measures of ram sperm competence and field fertility.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {181-185},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Previous work has show poor relationships between the maintenance of sperm motility and fertility after AI of ram semen. New laboratory tests of sperm competence have been developed but their relationship to fertility needs to be established. Two large scale trials involving the laboratory evaluation of straws of frozen semen from different rams and the field AI of ewes with the same batches of semen were conducted. In Trial A, 1671 ewes were AI{\textquoteleft}d with 52 batches of semen from 26 rams on 6 farms. In Trial B 6872 ewes were AI{\textquoteleft}d with 137 batches of semen from 34 rams on 25 farms. In Trial A, there was no linkage between farms while in Trial B the same batch was used on more than one farm and most farms had more than 1 batch from more than 1 ram. Laboratory evaluation involved: visual motility assessment post thaw and time taken to drop to 5\% motility when incubated at 38{\textdegree}C, 8 parameters of velocity and direction of motility using CASA; \% live and \% acrosome intact and sperm concentration. These parameters were measured immediately post-thaw and in Trial B a repeat measurement was made after 6h at 38{\textdegree}C. In addition, in Trial A the relative IVF value was determined. In Trial A there were significant (P<0.05) between farm and ram within farm effects on fertility (\% pregnant) but no ejaculate within ram effect. Significant (P<0.001) differences were seen in all semen parameters except initial motility, time to 5\% and concentration. Parameters correlated with fertility were IVF and \% live and together these accounted for 44 \% of the variation. In Trial B, there were effects of farm on fertility (P<0.001) and breed of ram (P<0.05), residual ram variation was non-zero but not significant. There were significant differences between rams and between ejaculates within rams in concentration, visual motility, \% live, velocity and directional parameters. The number of live and motile sperm inseminated was correlated (P<0.001) with fertility. Significant (P<0.05) correlations were also obtained between two CASA parameters; the \% live and \% visual motility, after 6h of incubation. Multiple regression equations were derived that accounted for between 62 and 75 \% of the variation between rams. },
	issn = {1176-5283},
	author = {Smith JF and Parr J and Murray GR and Clarke A and McDonald RM and Duganzich DM}
}
