@conference {41979,
	title = {Ultrasonic measurement of backfat and muscling in sheep selected for parasite-related traits},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {198-203},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {This paper reports on backfat depth and muscling comparisons of sheep selected for nematode parasiterelated traits. Results are from two AgResearch projects, the first located at Kaitoke Farm (Upper Hutt), in which experimental Romney lines wereselectively bred for susceptibility (S) or resistance (R) to nematode infection (high or low faecal egg count), or for resilience to nematode challenge whilst maintaining acceptable growth with minimal anthelmintic treatment (RL line); these lines grazed alongside an unselected control line (C). The second project was located at Ballantrae (Northern Wairarapa), in which Romney breeding lines were selected for resilience, with two replicate farmlets under {\textquoteright}Conventional{\textquoteright} parasite management (with anthelmintic treatment), and with two further replicate farmlets under {\textquoteright}Low-Chemical{\textquoteright} management. The four replicate lines at Ballantrae were serviced by rams of equivalent genetics, from elite RL-line sires bred at Kaitoke or Ballantrae. Ultrasonic backfat depth and eye muscle dimensions (length, depth and area) of ewe lambs from each project were assessed at 8-9 months of age (234 C-, S-, R- and RLline lambs born in 2003 at Kaitoke, and 154 resilient lambs born in 2004 at Ballantrae). Adjustments were made for significant fixed effects including covariate adjustment for live weight. No significant differences were found among the R, C and RL lines for either trait, but the S line had 5-10\% smaller eye-muscle dimensions (P < 0.05) than the other lines following an extended period of natural nematode challenge with minimal drench treatment. The two replicate lines under Low-Chemical management were 3.8 {\textpm} 0.6 kg (11.8\%) lighter in May than the replicates under Conventional management (P < 0.001). After adjustment for live weight, lambs in the Conventional treatments had 15\% larger eye-muscle areas (P < 0.001) but not backfat depths than those in the Low-Chemical treatments. Results suggest that muscle dimensions of the Sline lambs were more affected than those of their R-line counterparts by parasite infection, whilst the C-, R- and RL-line lambs did not differ significantly. At Ballantrae, even at equivalent live weights, the two Conventional replicates had more muscling but not fat depth than the two Low-Chemical replicates.},
	issn = {1176-5283},
	author = {Wheeler M and Morris CA and Bisset SA and Vlassoff A and Mackay AD and West CJ and Devantier BP}
}
@conference {41260,
	title = {Genetic studies of resilience of Romney sheep to nematode challenge in New Zealand},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {92-95},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {"Resilience" in sheep can be defined as the ability to withstand nematode challenge, and to maintain acceptable health and productivity, with minimal reliance on anthelmintic treatment. One heritable component trait is Total Drench Requirement (TDR), which is measured in lambs managed on a regime of "drench-on-demand" (where Trichostrongylus and Ostertagia are the predominant nematode genera in New Zealand sheep). A breeding experiment was established in 1994, selecting for increased resilience in Romney lambs. Currently, breeding ewes in the experiment are subdivided between Ballantrae, where four genetically equivalent sub-groups graze separate farmlets year-round, under Non-Chemical versus Conventional management (AgResearch{\textquoteright}s Low-Chemical Farming Systems Programme), and Wallaceville, where an Elite Resilient line was re-established in 1999 alongside the Control Faecal Egg Count (FEC) line. Selection responses up to 1999/00 in the Elite Resilient-line lambs (relative to the Control line) included a 27\% greater post-weaning weight gain (GAIN: Dec. to Apr.), a 0.48 unit reduction in dags, and a 45\% reduction in TDR (Dec. to Apr.). A favourable genetic correlation (-0.54) was recorded between TDR and GAIN in lambs, whilst that between TDR and log FEC was -0.17 (not significant). Mean autumn weights in lambs at Ballantrae were 5.8 kg (18\%) lower in the Non-Chemical than Conventional treatment groups (P<0.01). Through intense genetic selection, 51\% of Elite-line ram lambs are now resilient enough for low-chemical or organic production systems. },
	issn = {1176-5283},
	author = {Morris CA and Bisset SA and Vlassoff A and Mackay AD and Betteridge K and Alderton MJ and West CJ and Devantier BP}
}
@conference {40966,
	title = {Parasite resistance: A genome scan approach to finding markers and genes.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {297-300},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A  systematic  approach  for  finding  regions  of  the genome  that  are  important  in  the  control  of  productive traits  has  only  recently  become  available.  The  advent  of microsatellite  markers  for  sheep  and  other  domestic  ani- mals  (Crawford  et  al.  1991)  and their subsequent place- ment on linkage maps (Crawford  eta/.  1995, Kappa  et  al 1997)  has  provided  a  set  of  highly  informative  markers densely  spread  across the genome.  With these  reagents  we now  have  the  ability  to  follow  the  inheritance  of  each region  of  every  chromosome  in  any  cross.  Providing  we have  pedigrees  in  which  genes  which  have  an  important influence  on  the  trait  of  interest  are  segregating,  we  can systematically  identify  the  regions  of  the  genome  in- volved.  This  process  has  become  known  as  the  genomic scan. },
	issn = {1176-5283},
	author = {Crawford AM and Green R and Cuthbertson RP and Wright C and Vlassoff A and Squire DR and West CJ}
}
