@conference {41434,
	title = {Heritability of Johne{\textquoteright}s disease and survival data from Romney and Merino sheep},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {179-182},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {Eight years of health records for ovine Johne{\textquoteright}s disease (OJD) from a long-term breeding trial with Romneys and Merinos at AgResearch{\textquoteleft}s Tokanui Station were analysed, to study the quantitative genetics of animal resistance/susceptibility to OJD. Necropsy records were used in preference to serology to determine OJD status. A total of 2348 Romney and 1297 {\textquoteleft}Merino{\textquoteleft} ewe records (5 groups: two purebred Merino groups (Australian imported superfine and NZ purebred Merino), two Merino x Romney halfbred groups and a superfine Merino back-cross) were analysed for OJD and survival, comprising animals born between 1971 and 1978. Few males were retained past two years of age, so disease and survival data on males were excluded. Romney ewes had a mean lifetime incidence of OJD of 3.49\% (range, by year of birth, 2.11 to 5.00\%), whilst the mean for Merino ewes was 4.78\% (range, by year of birth, 0.0 to 7.74\%). The breed contrast approached significance (P<0.051). The mean age at OJD incidence was 3.44 {\textpm} 0.09 years for Romneys, compared with a mean age for surviving females in the sample of 5.04 {\textpm} 0.02 years (P<0.001). Corresponding means for Merinos were 3.38 {\textpm} 0.13 and 5.00 {\textpm} 0.04 years, respectively (P<0.001). The heritability of lifetime incidence of OJD, considered as a binomial trait and using animal-model restricted maximum likelihood methods, was estimated as 0.07 {\textpm} 0.14 and 0.18 {\textpm} 0.11 for Romneys and Merinos respectively, giving an overall value (pooled within breeds) of 0.14 {\textpm} 0.09. Adjusting for Merino group in the relationship matrix (rather than as a fixed effect) led to a heritability for Merinos of 0.24 {\textpm} 0.09. These estimates may be biased upwards by {\textquoteleft}vertical transmission{\textquoteleft} of OJD organisms from dam to offspring. The heritability of age at death/culling had values of 0.11 {\textpm} 0.04 and 0.16 {\textpm} 0.05 for Romneys and Merinos respectively, with a pooled value of 0.13 {\textpm} 0.03. With the low heritability estimates for OJD in Romneys it is concluded that traditional breeding methods to reduce the incidence would be slow or unsuccessful; however, for Merinos, selection could begin to reduce the incidence, but ranking later generations may become difficult. },
	issn = {1176-5283},
	author = {Hickey SM and Morris CA and Dobbie JL and Lake DE}
}
@conference {41198,
	title = {Genetic parameters for improvement of dual-purpose flock productivity with constraints on mature ewe body weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {60},
	year = {2000},
	month = {Jan},
	pages = {203-206},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {SIL provides opportunity for inclusion of information on mature ewe body weight in animal evaluations. This paper reports estimates of the parameters needed for these evaluations. Traits analysed were: weaning weight (WWT) and hogget liveweight in May (ALW); hogget yearling liveweight (HLW) and greasy fleece weight (HFW); and pre-mating body weights (ELW), number of lambs born (NLB) and greasy fleece weights of ewes at 2 to 5 years of age. EFW and especially ELW, were highly repeatable (>0.9), the pattern of genetic correlations suggesting that breeding ewes had reached maturity in these traits by 40 months of age. Direct and maternal genetic effects on WWT showed similar heritabilities (0.14{\textpm}0.02 \& 0.18{\textpm}0.02) and were positively correlated (0.20{\textpm}0.08). Maternal influences on traits measured at old ages were much reduced, direct heritabilities being similar to published estimates. WWT showed a high direct genetic correlation with LW8 and HLW (0.82{\textpm}0.02), but lower with ELW (0.70{\textpm}0.06 for 3-year old ewes). LW8 and HLW showed even higher direct genetic correlations with ELW (of the order of 0.90{\textpm}0.02). EFW was highly correlated genetically with HFW (0.80{\textpm}0.03), HLW (0.25{\textpm}0.04), ELW (0.23{\textpm}0.05) and LW8 (0.21{\textpm}0.04). Dual-purpose genetic response predictions were derived using SIL{\textquoteright}s recently revised relative economic values for a dual-purpose index. Its correlation with aggregate breeding value was 0.67. It predicted positive selection responses (per generation and standard deviation of selection pressure) in all traits: LW8 (2.1 kg), EFW (0.14 kg), NLB (0.038 lambs/ewe) and ELW (2.4 kg or 87\% of the predicted single trait response despite the negative economic weight for this trait). Restraining the response in ELW to zero required a ten-fold increase in the negative relative economic value for this trait, and reduced the correlation of the index with aggregate breeding merit to 58\% of its previous value. Such restriction greatly increased the relative contribution of fleece weight to economic response, made little difference to the contribution of NLB (although the absolute rate of progress was nearly halved), and reduced the contribution of growth; maternal effects on weaning weight became relatively more important. },
	issn = {1176-5283},
	author = {Clarke JN and Dobbie JL and Jones KR and Wrigglesworth AL and Hickey SM}
}
@conference {41063,
	title = {Sex and age effects on genetic parameters for wool production and qualities},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {23-26},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Heritabilities and genetic correlations were estimated for New Zealand Romney sheep from within the selected and control lines of a 25-year selection experiment for greasy hogget fleece weight and yearling body weight. Average repeatability of clean fleece weight in 1 to 5 year-old ewes was 0.56, 25\% higher than the average heritability of 0.44. The average genetic correlation among measurements at different ages was 0.89. Sexual dichotomy in the relative predictive power of hogget records was most apparent for greasy and clean fleece weights but was evident to some degree for bulk and brightness as well, due mainly to lower heritabilities in male compared to female hoggets. Average co-heritability of greasy hogget with adult clean fleece weights was 25\% lower for male (0.26) compared to female (0.35) hoggets, in this case due to a lower genetic correlation (0.69 vs 0.81) as well as a lower heritability (0.33 vs 0.43, respectively). A repeatability model seemed an adequate approximation for estimation of breeding merit for most wool quality traits studied but not for lifetime wool production. },
	issn = {1176-5283},
	author = {Clarke JN and Dobbie JL and Jones KR and Wrigglesworth AL and Hickey SM}
}
@conference {41010,
	title = {Effect of sire genotype on lamb growth and carcass productivity},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {136-139},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The growth and carcass traits of 774 lambs out of Romney ewes and sired by Suffolk (S), Landcorp Lamb Supreme (LS), Texel (T) and Romney (R) rams were compared when slaughtered on five occasions (groups 1 to 5): November 1995, February, March, May and July 1996. Forty carcasses per slaughter group were dissected into commercial cuts of saleable meat, fat trim and bone. S- and LS-sired lambs had heavier pre-slaughter liveweights than T-sired lambs (38.4 {\textpm} 0.27, 38.5 {\textpm} 0.26, vs 36.3 {\textpm} 0.27 kg respectively; P<0.001), which in turn were heavier than R-sired lambs (35.0 {\textpm} 0.29 kg; P<0.001). S-sired lambs had heavier hot carcass weights than both LS- and T-sired lambs in slaughter groups 4 and 5 (+0.9 to +1.9 kg; P<0.01); R-sired lambs were significantly lightest in all slaughter groups (-0.7 to -3.9 kg; P<0.05). S- and R-sired lambs had greater adjusted GR tissue depths than LS-sired lambs in later slaughter groups. T-sired lambs were generally intermediate between LS- and R-sired lambs. R-sired lambs produced less weight of saleable meat than S-, LS- and T-sired lambs (by 1.4 to 1.7 kg; P<0.01). Lambs sired by Landcorp{\textquoteright}s terminal sire breeds out-produced those sired by the company{\textquoteright}s maternal R sire breed. S-sired lambs exhibited rapid growth early in the season, but increased fat levels later in the season compared with LS-and T-sired lambs. },
	issn = {1176-5283},
	author = {Nicoll GB and Skerritt JW and Dobbie JL and Grimwood TJ}
}
@conference {41048,
	title = {Seasonality of wool growth in Waikato and Southland of Romney sheep selected for high fleece weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {270-273},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Wool growth rate was estimated for a total of 525 Romney ewes born in 1991 and 1992 between 5 and 28 months of age. Both year born groups contained sheep from three flocks selected over an extended period for increased hogget fleece weight and their respective Control flock. One flock was located in the Waikato, one in Southland and one split between the two locations. Following adjustment for live weight the seasonality of wool growth rate in Southland was significantly greater than in the Waikato reflecting the sensitivity of Romney sheep in recognising small changes in the length of daylight between the two locations. Selection for increased hogget fleece weight resulted in a greater increase in relative wool growth rate during the winter than during the summer. },
	issn = {1176-5283},
	author = {Sumner RMW and Wuliji T and Dobbie JL and Andrews RN and Upsdell MP}
}
@conference {40955,
	title = {Comparison of weight-selected Romney hoggets for growth and ultrasonic fat and eye muscle dimensions.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {263-266},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Lines of Romney sheep selected for either weaning (WWW) or yearling body weight (TYW and HYW) for 25 years were compared relative to their respective controls in a common environment using two unselected crops of male and female progeny. The weaning weight (WWW) line and one of the yearling weight (TYW) lines were derived from a common base flock, of diverse origin. The WWW line maintained a similar body weight advantage of approximately 20\% over its control at 5, 8, 10 and 14 months of age. All control lines showed very similar average body weight trends with age (28.0{\textpm}0.5, 33.9{\textpm}0.05, 35.3{\textpm}0.06 and 42.6{\textpm}0.7). In contrast the yearling weight lines showed increasing divergence with age from 22\% in February to 28\% (TYW) and 31\% (HYW) at 13 months. All lines, and especially the yearling weight lines showed some weight increase over the winter (May to July). Eye muscle depth and width changed little over the winter compared with the previous autumn or the following spring, in contrast to fat depth trends which increased in all lines but for which however, there was little line divergence among the yearling weight lines during the winter. All selected lines had significantly lower eye muscle dimensions at the same liveweight than their controls (by 4\% for width and 5\% for depth). Lines also showed contrasting divergence in average weight-adjusted fat depth relative to their controls, especially those derived from the same base population. As judged by reductions in subcutaneous fat depth, the WWW line lost its initial leanness superiority (4\% lower fat depth) during the winter, the TYW line increasing its superiority (16-17\% lower fat depth) during the winter and spring. The other yearling liveweight line (HYW) showed only half the leanness superiority over its control at these times. Thus, lines selected for improved growth alone had different patterns of muscle and especially subcutaneous fat development in a desirable direction for commercial lean lamb production, but responses were variable. },
	issn = {1176-5283},
	author = {Clarke JN and Dobbie JL and Jones KR and Uljee AE and Wrigglesworth AL}
}
@conference {40956,
	title = {Muscle distribution in lamb progeny from several breeds.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {267-270},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Leg and shoulder composition (fat, muscle and bone) and some linear fat and muscle distribution measurements were taken on 458 lambs produced by 39 strains and breeds of ram born in 1992, 1993 and 1994. Lambs were either Romney or Romney-cross. Texel-cross lambs had the highest proportion of muscle in the leg and shoulder cuts with the Poll Dorset-cross lambs having a similar amount. Southdowns, American Suffolks and Romney strains had least muscle, and apart from the American Suffolk, also had most fat. The fat selected Southdown-cross had the highest \% carcass fat. There was no significant difference between any of the sire groups in the proportion of the major defatted leg primal cuts. All genotypes had a similar leg muscle cut distribution, breed differences being only in the relative proportions of muscle to fat and bone. The Texel-cross had the highest weight (at the same carcass weight) of psoas muscle and the ultrasonically selected Poll Dorset progeny had the highest proportion of measured lean as longissimus muscle. },
	issn = {1176-5283},
	author = {Kirton AH and Duganzich DM and Mercer GJK and Clarke JN and Dobbie JL and Wilson JA}
}
@conference {40809,
	title = {Repeatabilities of blood plasma metabolites and their associations with leanness in genotypes showing a wide divergence in carcass composition},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {180-183},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Strain differences in lean : fat partitioning were typified by a marked  contrast in a lean growth index giving equal but opposite emphasis to the  weights of protein and fat, in line with previous publications. Strains  showed characteristic differences in blood metabolites which did not  necessarily reflect genetic variations within a strain and correlated responses  to within-breed selection for changes in body composition. High repeatabilities of blood metabolites within a strain were found for  pasture-fed lambs aged between 5 and 14 months for samples collected on  the same day following overnight fasts of 20 vs 24 hours, but were lower for  samples taken from fasted animals at different ages. Between-age within- strain repeatabilities (averaged across two trials) were moderate for plasma  urea (0.24) creatinine (0.38) and non-esterified fatty acids (0.18), but low for  beta-hydroxybutyrate (0.09). Similar moderate heritability estimates were  found for urea and creatinine. Although standard errors were very high for  this small dataset based on only 12 sires, estimates for carcass composition  were in broad agreement with other more reliable published values. Also in  line with other results, sire-progeny variations in urea and beta- hydroxybutyrate were more positively related to carcass protein than carcass  fat, while the reverse was true for creatinine. Metabolically contrasting pairs  of metabolites showed potentially useful predictive associations with sire- progeny variations in protein:fat partitioning.},
	issn = {1176-5283},
	author = {Clarke JN and Binnie DB and Dobbie JL and Jones KR and Mowat CM and Purchas RW and Uljee AE}
}
@conference {40683,
	title = {Evaluation of muscling using Texel and Oxford cross Romney and Hight Romney lambs},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {55},
	year = {1995},
	month = {Jan},
	pages = {108-110},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Selection for out-of-season breeding ability could be enhanced if an  early indication of the trait was available. The onset of hogget oestrus has  been proposed as such a trait and has been examined for 362 ewe progeny  coming from early and late-lambing selection lines over 3 years.   In each year the early lambing (BV-) hoggets had an earlier (P<0.05) mean  date of onset of oestrus than the hoggets from the late-lambing (BV+) line.   In 1992 and 1993 this effect was confounded by the season of birth such that  nearly all the BV- animals were autumn born (AB) and the BV+ animals  born in the spring (SB). In 1993 animals from both lines were produced in  both seasons. Their mean day of first oestrus in 1994 (expressed as day of  year },
	issn = {1176-5283},
	author = {Kirton AH and Mercer GJK and Clarke JN and Dobbie JL and Duganzich DM and Wilson JA}
}
@conference {40732,
	title = {Genetic parameters of lifetime wool production},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {55},
	year = {1995},
	month = {Jan},
	pages = {268-271},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Heritabilities and genetic correlations were estimated from the selected  and control lines of a 25-year selection experiment for hogget greasy fleece  weight (GFW). The heritability of GFW was higher in the selected than the  control line and in female hoggets (0.48) compared with males (0.32). Inter-  age genetic correlations were less than unity, and higher in fleece weight  selected animals. Average genetic correlations between hogget and adult  records were higher in ewe than ram hoggets. Together these parameters  gave co-heritability estimates (pooled across lines) for greasy hogget with  clean adult ewe fleece weights of nearly half the average magnitude in males  (0.21) compared with female (0.36). These results have important  repercussions to the design of effective selection strategies for improvement  of lifetime wool production.  },
	issn = {1176-5283},
	author = {Clarke JN and Dobbie JL and Hickey SM and Jones KR and Wrigglesworth AL}
}
@conference {40529,
	title = {Plasma prolactin in Romney sheep selected for hogget fleece weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {53},
	year = {1993},
	month = {Jan},
	pages = {371-376},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Seventy nine mature, alpacas were scanned every 10-14 days using real time ultrasonography to visualise the foetus. There was a 24\% foetal loss between days 21-30 of gestation and parturition, with the maximum loss occurring between days 21-30 and days 31-40 of gestation. There was a 5\% loss of foetuses after day 100 of gestation.},
	issn = {1176-5283},
	author = {Clarke JN and Pearson AJ and Sumner RMW and Johnson DL and Dobbie JL and Wildermoth JE and Wrigglesworth AL}
}
@conference {40331,
	title = {Comparative wool production of Texel, Oxford Down, Finnish Landrace and Romney sheep},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {51},
	year = {1991},
	month = {Jan},
	pages = {303-308},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Two lines of Perendale sheep selected for an against loose wool  bulk as yearlings at hogget shearing were established at Whatawhata  Research Centre in 1987. Each line consists of approximately 100 mixed  age breeding ewes.   At ewe hogget shearing in 1989 loose wool bulk of the selection lines  differed by 5.2},
	issn = {1176-5283},
	author = {Dobbie JL and Sumner RMW and Clarke JN and Speedy PM}
}
@conference {40177,
	title = {Seasonal pattern of ovulation in Merino Romney and Merino x Romney ewes},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {249-254},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Effects of liveweight change during pregnancy and ewe shearing on lamb birth weight were studied using highly fecund Booroola-Merino cross Coopworth ewes. Following stratification on the basis of ewe live weight (mean 53.7 kg), age, breed, condition score, and previous (187) litter size, ewes were randomly allocated to a high (H) or low (L) early pregnancy (0.-49 days) nutritional treatment. Ewes on treatments L and H were offered sufficient feed to change their average live weight by 0 and 3 kg respectively between mating and 7 weeks post-mating. On the basis of litter size estimated by ultrasound scanning on day 50 of pregnancy, each of the 2 ewe groups was subdivided and allocated to one of 2 mid-pregnancy nutritional treatments (h and L) designed to change ewe body weight (live weight less conceptus weight) by 3 and 0 kg respectively in 7 weeks. One hundred and nineteen days after mating, half the ewes in each of the 4 nutritional subgroups were shorn and fed to the estimated metabolisable energy (ME) requirement of unshorn ewes. Lamb birth weights were recorded twice daily and within 12 hours of birth for 221 lambs born to 102 ewes conceiving at synchronised oestrus. High level of nutrition of ewes in early pregnancy increased birth weight of lambs by 46 (},
	issn = {1176-5283},
	author = {Smith JF and McGowan LT and Dobbie JL and Smart SH}
}
@conference {40117,
	title = {Follicle and fleece characteristics of Merinos, Romneys and Merino-Romney crossbreds},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {48},
	year = {1988},
	month = {Jan},
	pages = {195-200},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {In the first of 2 experiments, the milk production, food conversion efficiency, and grazing uniformity of Friesians and Jerseys were compared during a grazing trial of 21 d duration in mid lactation. Four groups of each breed, consisting of 12 cows per group, were offered pasture allowances of 10, 20, 30 or 40 kg dry matter (DM)/cow/d. In experiment 2, the energy metabolism of 6 Jerseys and 6 Friesians was compared by means of open circuit calorimetry. Energy balances were established for each cow when offered pasture at ad libitum, and at 75\% National Research Council (NRC) requirements. In Experiment 1, on average Friesians produced 26\% more milk, 6\% more milkfat, 13\% more protein and 24\% more lactose. At the lowest level of feeding (10 kg DM allowance/cow/d) Friesians produced more milk but less milkfat and protein than the Jerseys. Friesians consumed more pasture dry matter (av 13\%), lost more live weight and had a lower food conversion efficiency (61 v 67 g milkfat/kg DM consumed) than the Jerseys. It was calculated that milkfat per ha, at a common live weight was lower for the Friesians than Jerseys particularly at high rates of stocking. Partitioning of gross energy into digestible energy or metabolisable energy was not significantly affected by breed in Experiment 2, but the efficiency of utilisation of metabolisable energy for milk and tissue (balance energy) was higher for Jerseys than Friesians (0.58 v 0.48 respectively). The results suggest that in mid lactation Friesians produce more milk and milk solids per cow than do Jerseys because of the greater feed intake of Friesians. In contrast, the higher food conversion efficiency, utilisation of metabolisable energy and dry matter consumption per unit live weight of Jerseys allows them to achieve a higher production per hectare than the Friesians. Comparisons between breeds at other stages of lactation is warranted, particularly in light of current discussions about the system of payment for milk.},
	issn = {1176-5283},
	author = {Meikle HE and Wickham GA and Rae AL and Dobbie JL and Hickey SM}
}
@conference {39468,
	title = {The effects of decreasing liveweight at mating on reproduction in Romney ewes},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {35},
	year = {1975},
	month = {Jan},
	pages = {91},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	issn = {1176-5283},
	author = {Dobbie JL and Welch RAS and Ackerley JG and Lake DE}
}
