@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 {41089,
	title = {Field data analysis of lamb survival and mortality rates occurring between pregnancy scanning and weaning},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {98-100},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Ultrasonic scanning for pregnancy diagnosis in commercial sheep flocks has highlighted the magnitude of lamb loss from scanning to docking or weaning. From seven ram breeding flocks in Landcorp Farming Limited, lamb survival rates were derived from the number of lambs per ewe present at six stages: pregnancy scanning, birth, born alive, 48h after birth, end of lambing and weaning. Differences in lamb survival rates between adjacent stages provided the mortality rates for five intervals: pregnancy scanning-birth; birth-born alive; born alive-48h after birth; 48h after birth-end of lambing; end of lambing-weaning. Flock-year affected lamb survival rate at all stages (P<0.001) but varied with ewe age and lamb birth/rearing rank (P<0.001). Mean lamb survival rates for 3- and 4-year-old dams were generally higher than those of other dam age groups. Triplet-reared lambs had consistently lower survival rates than single- or twin-reared lambs (P<0.001). Lamb mortality rates for the five intervals were 0.03, 0.08, 0.03, 0.03 and 0.04 lambs per potential lamb at scanning, respectively. Lamb mortality was highest at birth, with lower survival rate of triplet-born lambs compared with single- and twin-born lambs (0.82{\textpm}0.006 vs 0.93{\textpm}0.004 and 0.93{\textpm}0.002 lambs per potential lamb respectively; P<0.001). The results indicated when, and to what extent, lamb losses occurred in the field between pregnancy scanning and weaning, and the importance of applying appropriate ewe/lamb feeding and management policies to minimise lamb mortality rates. },
	issn = {1176-5283},
	author = {Nicoll GB and Dodds KG and Alderton MJ}
}
@conference {40394,
	title = {A terminal sire breeding programme based on screening for hogget liveweight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {52},
	year = {1992},
	month = {Jan},
	pages = {125-128},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Eighty mature fallow deer does were allocated to four treatment  groups (n+20) for which oestrous synchronization treatment consisted of  intravaginal insertion of single CIDR devices for 14 days and  prostaglandin administration on days 0 and 10 of device insertion.  Treatment groups were staggered successively by 7-day intervals from  early March to late May, the period spanning the natural mating season  (rut). Observations to determine the onset of oestrus were performed  24-72 hours after CIDR device withdrawal and blood samples were  collected four times during insertion and then every 2 days, for 14  days, from CIDR device withdrawal. Plasma samples were analysed for  progesterone concentration to determine luteal development. A group of  untreated contemporary control does were allowed to mate naturally to  crayon-harnessed bucks to determine the period of the 1990 natural rut.  Oestrus and ovulation were detected on 69\% and 80\% of occasions  respectively following CIDR device withdrawal, with ovulation following  oestrus on 98\% of occasions. Ovulation not preceded by observed  oestrus, probably representing silent ovulations, occurred early in the  breeding season. There was complete failure of response, in terms of  does exhibiting oestrus increased from 0-10\% to 89-100\% with the  greatest coinciding with the onset of the natural rut. In addition, the  mean interval from CIDR device withdrawal to onset of oestrus tended to  decrease from between 71-88h to 47-63h and oestrous synchrony improved  progressively during the trial. The efficacy of CIDR devices in  synchronizing oestrus and ovulation in fallow deer does is clearly  influenced by timing of treatment relative to the natural breeding  season of the herd.  },
	issn = {1176-5283},
	author = {Nicoll GB and Alderton MJ and Annandale DD and Coleman ID and Grimwood TJ and Thomson JA}
}
@conference {40165,
	title = {Estimates of environmental effects and genetic parameters for live weights and fleece traits of Angora goats},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {183-190},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Low voluntary intake and animal performance with perennial ryegrass has been attributed to its high leaf strength. Perennial ryegrass populations were selected for high or low shear strength and individual plants of low (LS) and high (HS) selections grown in a controlled environment. Shear strength of LS leaves (290 g) was half that of HS leaves. LS leaves were shorter, narrower and lighter. However, shear strength of LS remained significantly lower after adjustment for differences in leaf width. Shear strength in both selections declined from leaf base to leaf tip. LS leaves contained less sclerenchyma but had similar vascular tissue content. Sclerenchyma was significantly correlated with shear strength (r=0.82). Chopped leaves (5 cm) from both selections, placed in polyester bags were subjected to rumen microbial digestion. The higher shear strength of HS selected plants was maintained for at least 24 h rumen digestion. It is concluded that lower shear strength was a result of decreased sclerenchyma content and that potential improvements arising from easier breakdown would be maintained during rumen digestion in vivo.},
	issn = {1176-5283},
	author = {Nicoll GB and Bigham ML and Alderton MJ}
}
@conference {40166,
	title = {Romney male and female heritabilities and genetic correlations for weaning, autumn and spring body weights and hogget fleece weights},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {191-196},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Five mixed-age Coopworth ewes were offered a pelleted low Mg (1.0 g Mg/kgDM) diet at the rate of 800 g/d for 2 months. Five levels of MG (0, 0.5, 1, 2 and 4 g Mg/d) in 230 ml deionised water were infused into the distal ileum for 48 h, followed by a recovery period of 24 h. The treatments were randomly allocated to each animal using a latin square design. Mg absorption from the large intestine was estimated from changes in plasma Mg concentration and urinary Mg excretion rate. Twelve h after commencement of infusion, plasma Mg concentration was higher at 4 g Mg than at 0g. There was a positive relationship between the amount of Mg infused and urinary Mg excretion. However, the percentage of infused Mg that was absorbed declined from 18.2\% to 6.9\% when Mg infusion rate was increased from 0.5 to 4 g Mg/d. In a second experiment, using a cross-over design, increasing the amount of water infused, with 4g Mg/d, from 230 to 2300 ml decreased urinary Mg excretion. The results show that Mg can be absorbed from the large intestine in significant amounts and indicate that a passive transport mechanism may be involved.},
	issn = {1176-5283},
	author = {Parratt AC and Nicoll GB and Alderton MJ}
}
