@conference {3672,
	title = {Contract session: Application of genetic technologies to the New Zealand sheep industry},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {184-187},
	address = {Dunedin},
	abstract = { },
	issn = {1176-5283},
	author = {Jopson NB and Linscott EM and Young MJ and Dodds KG and Clarke SM and Rowe SJ and Byrne TJ and Alder GF}
}
@conference {3672,
	title = {Transfers of genetic merit through multiple-tiered breeding structures into trait expressions for commercial sheep production},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {97-100},
	address = {Dunedin},
	abstract = { In New Zealand, selection of both replacement females and sires based on performance is typically highly rudimentary in
multiplier and commercial flocks. Selection of ewes and rams in these tiers is frequently driven by soundness and overall condition
of selected animals and sometimes, based on whether or not the replacement candidate was born in a multiple litter. In breeder
flocks, selection is usually supported by knowledge of the genetic merit of candidates. In multi-tiered breeding schemes, genetic
progress is disseminated from the nucleus to the commercial tier through the transfer of males. Gene-flow principles can be applied
in the optimization of multi-tiered breeding schemes, particularly to define the proportion of genetic superiority expressed in an
individual, which also gets expressed in its descendants, in time, across tiers. The opportunity to increase the rate of progress
and reduce the genetic lag between tiers in integrated production systems might be exploited by selecting candidates from which
performance of the progeny can be predicted. The results of this simulation study demonstrate the long time delays of up to 25
years for genetic expressions to fully flow through a multiple-tiered breeding scheme. There was long time delay before genetic
progress realised in the nucleus was achieved in the commercial flocks. For example, it was approximately fourteen years until
70\% of benefits of genetic improvement in lambing and slaughter traits were captured in the commercial flocks. This delay was
mitigated when performance recording was implemented in the multiplier flock. This gain however, does not have the permanent
and cumulative properties of genetic progress achieved in the nucleus flock, and so needs to be continued each year for the benefits
to be maintained.},
	issn = {1176-5283},
	author = {Santos BFS and Byrne TJ and Amer PR and Gibson JP and Van der Werf JHJ}
}
@conference {79009,
	title = {A comparative analysis of genetic trends within the New Zealand sheep industry},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {72},
	year = {2012},
	month = {Jan},
	pages = {159-162},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Rates of genetic progress made by Dual Purpose and Terminal Sire flocks in the New Zealand sheep industry between 1990 and 2007 have previously been examined (Amer 2009) and showed substantial gains in the rate of progress since the introduction of Sheep Improvement Ltd. (SIL) and SIL-ACE (Advanced Central Evaluation). Key findings from this earlier study showed that the rates of genetic progress doubled following the introduction of SIL, and increased by a further 50\% after the introduction of the Beef + Lamb New Zealand Central Progeny test (CPT), which effectively evaluates the performance of key industry sires, providing the ... continued},
	issn = {1176-5283},
	author = {Sise JA and Byrne TJ and Jopson NB and Young MJ and Amer PR}
}
@conference {75896,
	title = {The role of breeding in reducing sheep GHG intensity},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {71},
	year = {2011},
	month = {Jan},
	pages = {162-167},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Invercargill},
	abstract = {Historic and potential future greenhouse gas (GHG) emission reductions resulting from genetic selection decisions in sheep have been quantified. Historic genetic trends in number of lambs born in maternal breeds and growth in terminal sire breeds were estimated to have reduced GHG emissions per kilogram of lamb carcass weight by 0.45\% and 0.09\% per year of genetic change, respectively. The implications of future selection using different indexes were also examined. Selection based solely on farm profits could lead to emission reductions per unit of product by 0.185 kg CO2-e/kg carcass weight, or a 0.59\% reduction in lamb carcass weight emissions per annum. Selection of sheep ignoring profit and solely targeting reduced GHG emissions per kilogram of lamb carcass weight could lead to emission reductions of 0.242 kg CO2-e/kg lamb carcass weight, equivalent to a 0.77\% reduction in total emissions per annum. However, doing this would come at a cost of 26.6 cents per breeding ewe reduction of 23.7\% per annum in annual genetic progress. An alternative index that provides a balance between reducing GHG emissions and improving farm profits was estimated to produce an annual 0.193 kg CO2-e/kg carcass weight or a reduction of 0.62\% reduction in emissions per annum in GHG emissions with minimal sacrifice in genetic improvement of farm profitability.
},
	issn = {1176-5283},
	author = {Ludemann CI and Byrne TJ and Sise JA and Amer PR}
}
@conference {60981,
	title = {A simulation model to partition ewe efficiency into component traits for genetic analysis},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {69},
	year = {2009},
	month = {Jun},
	pages = {223-227},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Ewe efficiency is extremely topical in the New Zealand sheep industry. This paper describes a stochastic simulation model which facilitates partitioning of a defined ewe efficiency equation into its component genetic traits. It accounts for, and simplifies, the complex and sometimes unfavorable interactions among components of ewe efficiency. The model tracks simulated genetic effects, inherited from the ewe{\textquoteright}s sires, in breeding ewes and their lambs for key performance recorded traits. The traits simulated are weaning weight, mature weight, number of lambs born, lamb survival, and longevity. Ewe efficiency is defined as the difference between value of lambs weaned and ewe and lamb costs, rather than as a ratio. Output value in NZ$ for the efficiency equation is computed on a ewe by ewe basis, as a function of number of lambs born, lamb survival and weight of lamb weaned, with each of these components partly influenced by one or more genetic effects inherited from simulated sires of the breeding ewes. Preliminary results from the model have identified litter size, ewe longevity, maternal lamb survival, and maternal weaning weight as being important drivers of ewe efficiency. The relative balance of their importance is influenced by farm production levels and environment. },
	issn = {1176-5283},
	author = {Sise JA and Shackell GH and Byrne TJ and Glennie SF and Amer PR}
}
@conference {42029,
	title = {Inheritance of chondrodysplasia in Texel sheep},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {68},
	year = {2008},
	month = {Jan},
	pages = {20-22},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Brisbane, Australia},
	abstract = {A skeletal chondrodysplasia (noncancerous abnormal cell growth affecting cartilaginous tissues) characterized by dwarfism and angular deformity of the forelimbs has been recognized in Texel and Texel cross lambs. Some affected lambs have normal co-twins indicating the disease is likely to be of genetic origin. This study outlines the mode of inheritance of the disorder. Three affected rams were mated to 221 unaffected ewes to generate 123 daughters, which were backcrossed by multiple sire mating with their sires the subsequent season to produce 83 lambs for evaluation. The time course of the morphological progression of the disease was recorded. Of the 46 lambs that were successfully diagnosed, 22 were affected with the condition and 24 were unaffected. This was consistent with a 50:50 ratio expected for recessive inheritance in a backcross between affected and carrier animals. Within sexes, 11 males (24\%) and 11 females (24\%) were affected with 10 males (22\%) and 14 females (30\%) were unaffected. This was not different (P<0.05) from a 0.25 proportion for autosomal recessive inheritance. Variation in the age of onset (16 days {\textpm} 7 days) and severity of clinical expression suggests variable penetrance, with semi-lethality. },
	issn = {1176-5283},
	author = {Byrne TJ and Blair HT and Thompson KG and Stowell KM and Piripi S}
}
