@article {3672, title = {Impact of winter near-maintenance or non-restricted feeding on growth and intramuscular fat content of yearling rams}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {141-145}, address = {Online}, abstract = {There is increased interest in genetic improvement in intramuscular fat in lamb due to its positive association with meat quality. Live-animal measures such as ultrasound or computed tomography scanning can enable genetic selection. The optimum time at which such measurements should take place is unknown. This study investigated levels of intramuscular fat in year-old rams. During the winter of 2020, ram lambs were fed on either a just-above-maintenance pasture diet (JAM) (n=119) with a target weight gain of 50 g/day, or non-restricted feeding (GAIN) (n=120) with a target weight gain of 180-200 g/day, with all rams slaughtered after 10 weeks of differential feeding. Both groups of rams were fed a ryegrass-dominant pasture. The target for the GAIN group was achieved with an average growth rate of 182{\textpm}42 g/day (range 76 to 293 g/day), however, for JAM group the average growth rate was 24{\textpm}64 g/day (range -212 to 126 g/day), with a third of the animals losing weight. The JAM group were split according to whether they had gained (JAM {\textendash} Gain) or lost weight (JAM {\textendash} Loss) for the analysis. There were differences (P<0.001) at the time of slaughter in early spring in carcass weight between groups (23.7{\textpm}0.35, 19.5{\textpm}0.40 and 17.0{\textpm}0.47 kg for GAIN, JAM {\textendash} Gain and JAM {\textendash} Loss respectively). The levels of intramuscular fat were low across all groups compared to levels normally observed in 6-8-month old ram lambs and with further differences (P<0.001) between the three groups (2.1{\textpm}0.08, 1.9{\textpm}0.09 and 1.4{\textpm}0.10 kg for GAIN, JAM {\textendash} Gain and JAM {\textendash} Loss respectively). More work is required to understand management systems that allow improved expression of the trait. Additionally, careful consideration needs to be given to winter grazing management of all young stock, as there is considerable variability in individual animals handling of winter maintenance feeding. Keywords: lamb; maintenance feeding; intramuscular fat}, issn = {1176-5283}, author = {PL Johnson and Knowler K and Mcrae KM and Bain WE and Pile G and Craigie CR and Rowe SJ} } @article {3672, title = {Investigating the potential for global positioning satellite data to provide information on ewe behaviour around the time of lambing}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {29-34}, address = {Online}, abstract = {Global positioning satellite (GPS) devices allow spatial-temporal data sets to be generated which can describe ewe movement around the time of lambing and can potentially be linked to traits of interest, such as the timing and location of lambing events and maternal outcomes including lamb weaning weight. Collar-mounted GPS units were fitted to 25 ewes during their anticipated lambing period. Lambing timing and site were estimated based on a minimum of twice-daily checks of the ewes. Lambing and GPS data were ultimately available for 15 ewes. From the resulting data set, several traits were calculated including the average distance deviation from the central point of the three-hour time block. During the birthing event (at a resolution of hours), the ewes changed their movement behaviour and remained close to the centralised point of the three-hour block. There were significant associations among the weaning weight of the ewes{\textquoteright} offspring (adjusted for rearing rank) and the GPS-derived traits: ewes that were comparatively inactive produced lambs with low weaning weights. Overall, this study demonstrates the potential of GPS-derived traits to be of relevance in studies investigating ewe behaviour around and after-lambing and its impact on production outcomes. Keywords: lambing; global positioning satellites; weaning weights}, issn = {1176-5283}, author = {PL Johnson and Welsh A and Knowler K and Pletnykov P} } @article {3672, title = {INVITED REVIEW: A review of the current sheep industry in New Zealand and opportunities for change to meet future challenges}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {1-15}, address = {Online}, abstract = {

Like all farming systems, sheep operations face increasing economic, environmental, cultural, and social challenges, including climate change and consumer expectations about their food. Genetic improvement has the potential to help with these challenges. This review explores the importance of genetic improvement on welfare and disease traits in meeting these challenges. For all wool breeds, there is a need for traits such as being polled, having a short tail and having a bare breech and a bare belly to ensure an ethical outcome. Sheep that either seasonally lose their fleece, or do not grow wool, represent an opportunity. Predicted climate change poses significant animal-health challenges, including the internal parasite Haemonchus contortus, facial eczema, flystrike and pneumonia, that are likely to encroach on a wider geographic range. Given consumer expectations around reduced chemical inputs and improved animal welfare, genetic improvement will play a critical role in developing sheep that are more tolerant to such health challenges. While several key physical characteristics required for the future exist in minor breeds currently in New Zealand, their performance under a range of New Zealand commercial farming conditions has not been evaluated. Some overseas breeds, such as Katahdin and Barbados Blackbelly, may offer opportunities. Consideration needs to be given to the use of novel gene pools both within and outside the New Zealand sheep industry for it to be able to meet future challenges. To achieve this end, more information is needed about the overall merit of these novel breeds, to be able to identify the best strategy to take towards breeding sheep that address the future needs of the New Zealand sheep industry. Keywords: sheep; genotypes; breeding; future

}, issn = {1176-5283}, author = {PL Johnson and Newman S-AN and Mcrae KM and van der Weerden T and Brown M and Scobie DR} } @article {3672, title = {Preliminary investigations into genetic variation in distance travelled by young sheep}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {63-67}, address = {Online}, abstract = {In pastoral grazing systems, animals need to walk to obtain nutrients (pasture) and water, however, it is also thought that the distance an animal travels is further influenced by factors including the grazing behaviour of the animal, its health status and its general motivation for moving. The purpose of this research was to investigate the repeatability and genetic variation in the trait of distance travelled for New Zealand sheep. Data were collected using global positioning satellite (GPS) collars fitted to 422 animals from three different groups of animals (Group). The animals were allowed ad libitum grazing. Progeny from 44 sires were represented in the data set. The GPS collars were fitted for up to 17 days. Given between-day variability in distance travelled depending on paddock attributes (size and feed availability) all data were scaled to a constant mean. A univariate repeated measures model was fitted to the data using ASREML, with Group fitted within the model, and day within Group fitted as the repeated measure. The heritability estimate for daily distance travelled was 0.36{\textpm}0.09, with a repeatability estimate of 0.51{\textpm}0.03. The results indicate that distance travelled is a repeatable trait at the individual animal level and is under moderate genetic control. Keywords: sheep; GPS; distance travelled}, issn = {1176-5283}, author = {PL Johnson and Cullen N and Hickey SM and Knowler K and Bryson B and Hall M and Pletnykov P} } @article {3672, title = {Sheep divergently selected for methane yield showed differences in meat fatty acid composition}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {173-178}, address = {Online}, abstract = {The purpose of this work was to investigate whether 18-month-old rams from the methane selection lines differed in their levels of soft tissue depth over the 12th rib (GR, as a proxy of carcass fatness) intramuscular fat (IMF), and the fatty acid composition of IMF. The rumen is the site of microbial biohydrogenation of consumed plant fatty acids and synthesis of unique microbial body fatty acids. It is known that there are differences in the microbiome and fermentation characteristics of sheep selected for and against methane production (methane selection lines). When comparing the high and low lines several differences were found. Rams from low-methane-yield-selection lines tended to have lower GR (P<0.06) than those from high line rams, but there was no evidence for a difference in levels of IMF between the lines (P=0.77). There were, however, many significant differences in the fatty acid composition (as a \% of total fatty acids) of the IMF between the lines. The IMF from the low-methane-yield line had a significantly (P<0.05) higher proportion of branched-chain fatty acids, and fatty acids that are associated with the early stages of the biohydrogenation pathways in the rumen, specifically conjugated linoleic acid (CLA) and C18:1 t11 but with less C18:0 stearic acid (the end product of biohydrogenation) and a significantly higher proportion of C16:1 t9 which is produced through β-oxidation of C18:1 t11. These results provide insight into how differences in sheep from the methane-yield selection line may influence the fatty acid composition of their fat. Keywords: Methane; sheep; intramuscular fat; fatty acid composition}, issn = {1176-5283}, author = {PL Johnson and Agnew M and Jonker A and Hickey SM and McEwan JC and Bryson B and Dodds KG and Rowe SJ} } @article {3672, title = {An association between circulating copper concentrations and gammaglutamyl transferase activity in sheep after exposure to the toxin sporidesmin}, journal = {New Zealand Journal of Animal Science and Production}, volume = {80}, year = {2020}, month = {09/2020}, pages = {34-38}, address = {Online}, abstract = {Copper is a potent catalyst of the reaction in which sporidesmin generates damaging free radicals causing facial eczema in grazing livestock in New Zealand. This study sought to investigate whether circulating copper at the time an animal is dosed with the toxin, influenced the way the animal responds to sporidesmin and whether the action of sporidesmin on the liver in susceptible animals results in changes to circulating copper. Serum copper concentrations (CU) together with gamma glutamyl transferase (GGT) activity, an indicator of bile duct damage, were opportunistically collected on over 400 animals from nine flocks in which the animal{\textquoteright}s tolerance to sporidesmin was commercially assessed through measuring its response to a known dose of the toxin. The association between CU concentration before the animals were dosed and natural log transformed GGT activity measured 21 days after the animals had been dosed was not significant, but there was a suggestive (P=0.06) interaction between flock and CU. There was a significant positive association between natural log transformed GGT activity and CU concentrations measured 21 days after the animals had been dosed with the toxin (P<0.0001). For some individuals, the CU concentrations approached or met copper-toxicity thresholds (above 40 μmol/L). The specific biological mechanisms causing this association remain unknown, but given the role of copper in catalysing the sporidesmin reaction and the potential of toxic copper concentrations, further research is warranted. Keywords: sheep; facial eczema; copper; gamma glutamyl transferase}, issn = {1176-5283}, author = {PL Johnson and Amyes NC} } @article {3672, title = {Predicting internal adipose from selected computed tomography images in sheep}, journal = {New Zealand Journal of Animal Science and Production}, volume = {80}, year = {2020}, month = {09/2020}, pages = {113-116}, address = {Online}, abstract = {Dairy cattle preferentially lay down internal (INT) (e.g., kidney) adipose relative to sub-cutaneous adipose (SCF) tissue, but this pattern is the opposite in beef cattle, which preferentially deposit adipose subcutaneously. It is proposed that these differential patterns of fat distribution evolved to match the different production drivers of these breeds. As the New Zealand sheep industry has become more diverse in terms of breeds and production systems, the role that differential adipose distribution could play in supporting different production systems is of interest. The potential to use commercially obtained Computed Tomography (CT) images (i.e., six images, selected to predict carcass attributes in the live animal), to additionally predict INTF in addition to carcass fatness, was investigated using a full set (i.e., 30-32) of CT images available on 50 maternal ewe lambs. The R2 between the fulland sub-set of images for absolute amounts ranged from 0.25 for bone to 0.92 for SCF, with INTF 0.77 (P<0.001). When adjusted for total weight, correlations were slightly reduced, but still supported the ability of the analysis of the six images to accurately identify animals with differential fat distribution. Future work will include analysis of a further 550 animals from the same data set to determine the genetic correlation between the full and subset of images. If successful, adipose distribution can be predicted from existing and future commercial CT data sets and used to investigate its genetic and phenotypic relationship with production traits. Keywords: internal adipose; subcutaneous adipose; computed tomography}, issn = {1176-5283}, author = {PL Johnson and Juengel JL and Bain WE} } @article {3672, title = {BRIEF COMMUNICATION: Carcass characteristics and meat quality of early, mid- and late-season commercial lambs}, journal = {New Zealand Journal of Animal Science and Production}, volume = {79}, year = {2019}, month = {07/2019}, pages = {80-83}, address = {Palmerston North}, abstract = {Comparisons were made of carcass and meat quality characteristics of three groups of wether lambs (n=15/group): a composite breed slaughtered at weaning (EARLY), and at 6-8 months of age (MID) and Merino lambs slaughtered at 12 months of age (LATE). Carcass weight and eye muscle area were measured and meat quality was measured on the Longissimus thoracis (loin). All lambs had similar carcass weights (18.7-19.0 kg; P>0.05). Meat from LATE lambs had higher ultimate pH and intramuscular fat \% (P<0.001) than EARLY and MID lambs. Loins from EARLY lambs had lower Chroma (P<0.01), higher eye muscle area (P<0.001) and shear force (P<0.05) and greater percentage of polyunsaturated fatty acids (P<0.001) than loins from MID and LATE lambs. Although statistical differences were observed in meat quality measurements, differences in absolute values suggest that the three production systems resulted in minor variation in meat quality.}, issn = {1176-5283}, author = {Ye Y and Schreurs NM and PL Johnson and Corner-Thomas RA and Agnew MP and Silcock P and Eyres GT and Maclennan G and Realini CE} } @conference {3672, title = {BRIEF COMMUNICATION: High ultimate pH in short-scrotum male lambs processed during the breeding season}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {194-196}, address = {Rotorua}, abstract = {

Historically in New Zealand male lambs were castrated at the time of docking, however, there has been a move to instead create short-scrotum males, in which the testes are pushed within the body cavity and the scrotum removed (Johnson et al. 2007). This results in short- scrotum males, having similar physiological characteristics to entire ram lambs, except that they are almost always infertile and, therefore, do not present a management risk if they are accidently mixed with ewes or ewe lambs during the mating season. The normal ultimate pH of lamb meat is considered to be 5.50 to 5.80, with values above 5.8 and in particular above 6.0 considered high, and resulting in negative meat quality outcomes. There have been a number of studies that have investigated whether or not sex differences in the ultimate pH of lamb exist. The results are not always consistent with some studies reporting elevated ultimate pH in non-castrated male lambs (Johnson et al. 2005; Bain et al. 2009), whilst others have shown no differences (Kerslake et al. 2012; Schreurs 2013). In commercial farming operations there is a mix as to how farmers manage their lambs of different sexes during the finishing period prior to slaughter, and in many farming operations this period coincides with the on-set of the breeding season.

Given the most recent papers in this area have concluded that there is no sex-effect on ultimate pH, the purpose of this paper is to report on data collected from a trial that set out to invoke high ultimate pH (to investigate potential live-animal predictors of high ultimate pH) in short-scrotum male lambs during the breeding season.

}, issn = {1176-5283}, author = {PL Johnson and Stuart AD and Mackie A} } @conference {3672, title = {BRIEF COMMUNICATION: Hot years in history and facial eczema}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {107-109}, address = {Rotorua}, abstract = {

Facial Eczema (FE) is caused by grazing animals ingesting the toxin sporidesmin which is produced by spores of the fungus Pithomyces chartarum. In order for the fungus to sporulate, a series of weather and environmental events must occur, with warm, moist, humid conditions and leaf dead-matter at the pasture base required (Brook 1969). In New Zealand, the combination of required conditions has historically been confined to summer and autumn months in temperate parts of New Zealand as illustrated in a map published by di Menna et al. (2009).

There is a large body of research that concludes that the world is in a period of climate change, characterised by increasing temperatures and extreme weather events (Ministry of Environment NZ, 2008) with the temperature increases predicted to incrementally increase into the future. Using climate change predictions, modelling work reported by di Menna et al. (2009) and Dennis et al. (2014) demonstrated that into the future the geographical regions in New Zealand affected by FE would increase, as temperature increases would result in more areas achieving the minimum temperatures required for sporulation.

Through using published literature and media articles prior to 2016, the worst years for FE in New Zealands history were 1938 and 1999. Indeed the outbreak in 1938 was what led to the establishment of the Ruakura Research Centre (now AgResearch) in an attempt to understand the cause and control of the then-unknown disease that had resulted in photosensitivity, liver damage, production losses and death in affected animals (di Menna et al. 2009).

The purpose of this paper is to report on the FE outbreak of 2016 and to draw temperature parallels to the outbreaks of 1938 and 1999 using weather data from the Ruakura Weather Station.

}, issn = {1176-5283}, author = {PL Johnson and Cameron CA and Henderson HV and Cullen NG} } @conference {3672, title = {BRIEF COMMUNICATION: Reduced reproductive outcomes in ewes susceptible to facial eczema}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {197-199}, address = {Rotorua}, abstract = {There are both clinical and sub-clinical effects on grazing ruminants that ingest the toxin sporidesmin produced by the fungus Pithomyces chartarum, with the clinical effects of the toxin giving rise to the colloquial name of the disease {\textquotedblleft}facial eczema{\textquotedblright}. The sub-clinical effects of Facial Eczema (FE) have been documented and impact on most aspects of production from fertility through to growth. Data used to estimate the effects of the sporidesmin ingestion have ranged from natural exposure to high levels of sporidesmin in the outbreak in 1981 (Moore et al. 1990) through to differences in genetic selection lines and in trials where animals are artificially dosed with sporidesmin (Morris et al. 1991). Whilst the size of the impact does vary between studies, their overall conclusions are consistent, with decreased ewe fertility observed. In all studies, how the animal has tolerated (or not) the sporidesmin that it has been exposed to, is estimated through measuring serum gamma-glutamyl transferase (GGT) levels which have been shown to be a strong indicator of liver damage, the body organ most directly affected by the toxin (Towers \& Stratton, 1978)...}, issn = {1176-5283}, author = {PL Johnson and Henderson HV and Proffit R and Cullen NG} } @conference {3672, title = {BRIEF COMMUNICATION: Relationship between measures of residual energy intake made on growing animals and adults}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {85-87}, address = {Rotorua}, abstract = {In New Zealand pasture-based sheep systems, young replacement ewe lambs and those lambs to be finished for slaughter, are often preferentially fed through summer, with ewes which have just weaned their lambs given secondary priority through until their pre-mating period. This is particularly the case in hill-country environments, in which an increasing proportion of the New Zealand ewe flock is farmed. Feed efficiency, defined as residual energy intake (REI), is a measure of whether or not an animal is eating more or less than expected for its live weight and growth rate. Of interest is whether or not animals described as efficient, or inefficient during their young growth phase, when on high-quality diets, continue to be so as an adult grazing sub-optimal feed during summer periods. There is limited comparable literature in sheep. The general finding of the beef cattle work is that the young and adult measures of REI are moderately phenotypically correlated and very highly genetically correlated, although in the most comprehensive study both the young and adults were fed the same medium-quality feed (Archer et al. 2002). In dairy cattle work, they have also found that calves divergent for REI during growth are also divergent for REI when lactating, although the size of the divergence was reduced (McDonald et al. 2014)...}, issn = {1176-5283}, author = {PL Johnson and Wing J and Knowler K} } @conference {3672, title = {Intramuscular fat content of New Zealand lamb M. longissimus lumborum}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {189-193}, address = {Rotorua}, abstract = {

The content of intramuscular fat (IMF\%) in lamb is an important trait for the lamb-meat value chain. Not only is IMF\% an import-ant energy reserve for replacement stock, IMF\% is an important driver of lamb-meat eating quality. A growing body of research shows an antagonistic relationship between muscle growth traits and fat content across the lamb carcass (including IMF\%). The New Zealand sheep industry has selected for muscle growth traits for decades to improve production efficiency and reduce extremes of carcass fatness historically observed, but the impacts on IMF\% levels in New Zealand lamb have not been widely investigated.

This paper aims to stimulate discussion on lamb IMF\% by reporting on levels of IMF\% observed in the M. longissimus lumborum (LL) of 1,705 progeny test lambs raised under extensive, pasture-based production systems across New Zealand, and investigates the relationship between IMF\% and carcass weight, VIAscan{\textregistered}-predicted GR (VSGR) and lean-meat-yield percentage (VSYLD).

The average IMF\% was 2.69\%, (SD = 0.83\%, and ranged between 0.91-6.42\%). IMF\% is positively correlated with carcass weight and VSGR and negatively correlated with VSYLD. Considerable variation exists in lamb IMF\%, highlighting the opportunity to manage IMF\% through genetic improvement and optimised on-farm management.

}, issn = {1176-5283}, author = {Craigie CR and Agnew MP and Stuart AD and Shorten PR and Reis MM and Taukiri KR and PL Johnson} } @conference {3672, title = {BRIEF COMMUNICATION: An update on genetic parameters for facial eczema tolerance in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {43-45}, address = {Adelaide}, abstract = {Facial Eczema (FE) is a metabolic disease resulting from liver and bile-duct damage, caused by ingestion of the mycotoxin sporidesmin A, found in the spores of the fungus Pithomyces chartarum. Risk of FE is associated with temperature, humidity and dead leaf matter (Mitchell et al. 1959; Brook 1963; Di Menna \& Bailey 1973). While FE is predominantly prevalent in the North Island of New Zealand, climatic change projections indicate that there will be an increase in the geographical spread of the fungus and associated sporidesmin, resulting in FE spreading to regions that are currently unaffected (Dennis et al. 2014). Clinical FE is characterised by photosensitisation due to liver injury; however, reduced production (Smith 2000) and reproduction (Moore et al. 1983; Mcmillan et al. 1988; Morris et al. 1991) is also observed in both clinically and sub-clinically affected animals. The heritability of liver damage at slaughter post-sporidesmin challenge was estimated to be 0.42 {\textpm} 0.09 (Campbell et al. 1981). In the live animal, serum gamma glutamyltransferase (GGT) collected 2 to 3 weeks after sporidesmin challenge can be used as a measure of liver damage (Towers \& Stratton 1978). Romney FE selection lines, initially selected for resistance or susceptibility on the basis of liver damage, were established in 1975...}, issn = {1176-5283}, author = {Mcrae KM and Cullen NG and Amyes NC and PL Johnson} } @conference {3672, title = {Preliminary investigations into the trait of residual energy intake in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {34-37}, address = {Adelaide}, abstract = {Residual energy intake (REI), also referred to as residual feed intake, is one way of describing feed efficiency, and is an estimate of whether or not an animal is eating more or less than expected for its weight and growth rate. The REI trait has been investigated in a number of production-animal species, but only pilot study data exists for New Zealand sheep. This paper investigates phenotypic variability in the trait of REI for a cohort of 197 growing ewe lambs. The animals were approximately nine months old at the commencement of the trial. Their daily intake of a lucerne pellet-diet was measured for 56 days using an automated feeder that recorded weight of feed consumed in real time. The animals were weighed twice weekly. The standard REI model involves fitting metabolic mid-test live weight and live weight gain to predict energy intake. Both measurements fitted were significant (P<0.001), with an overall R2 for the model of 0.78. Grouping of the animals in to Low-, Mid- and High-efficiency groups revealed a 24\% difference in energy intake between the low and high groups which is consistent with studies in other species. The comparison of attributes of the efficiency groups did reveal differences in fatness with the high-efficiency animals fatter at the start of the data collection, but they did not lay down as much fat during the trial as the low-efficiency group. Given the phenotypic variability is consistent with that observed in other production-animal species, additional cohorts will be measured in the coming years to generate a data set to investigate the genetics of the trait, and further investigate the role of fat within the REI model.}, issn = {1176-5283}, author = {PL Johnson and Miller SP and Knowler K} } @conference {3672, title = {Variation in total body adipose and adipose partitioning in maternal sheep estimated using computed tomography scanning}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {122-125}, address = {Adelaide}, abstract = {In sheep, decreasing adipose or fat is desirable in prime lambs; however, adipose also has a role in the productive capacity of the maternal ewe. There are three main depots of adipose within the body of a live animal: sub-cutaneous, intermuscular and internal (or visceral). To understand if differences exist between animals in adipose deposition and partitioning, a study was undertaken using 37 New Zealand composite-breed maternal ewes, scanned using computed tomography on three occasions from nine through to 17 months of age. The images produced were processed to estimate the weight of subcutaneous, intermuscular and visceral adipose (along with lean and bone), with the weights then expressed as a percentage of total adipose to investigate partitioning. The raw average total body adipose remained proportionate across the three scans at approximately 32\% of total empty body weight. The resulting data were analysed using a REML variance components analysis in Genstat. The repeatability of fat distribution across the three scans was high, ranging from 0.77 for proportion of intermuscular adipose through to 0.83 for proportion of subcutaneous adipose. The component Animal was significant for all traits indicating between animal variation in partitioning of adipose between the depots within individual animals. Cumulatively, these results demonstrate that there is variability in adipose deposition and partitioning in New Zealand sheep. If under genetic control, variability that could be exploited to optimise adipose to best meet the requirements of prime lamb production and maternal ewes.}, issn = {1176-5283}, author = {PL Johnson and Bain WE and Johnstone P and Bixley M and Knowler K} } @conference {3672, title = {BRIEF COMMUNICATION: Genetic parameters for meat traits assessed in the Headwaters New Zealand Progeny Test}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {111-113}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {PL Johnson and Charteris A and Tate ML and Dodds KG} } @conference {3672, title = {BRIEF COMMUNICATION: Intake of ewe lambs is influenced by the dry matter percentage of the feed consumed}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, address = {Dunedin}, issn = {1176-5283}, author = {PL Johnson and Miller SP and Knowler K and Bryson B and Dodds KG} } @conference {3672, title = {BRIEF COMMUNICATION: Modelling liveweight change to inform residual feed intake models in growing lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {225-227}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {PL Johnson and Miller SP and Knowler K and Bryson B and Dodds KG} } @conference {3672, title = {BRIEF COMMUNICATION: Onset of breeding season in Dorset Horn ewes}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {PL Johnson} } @conference {3672, title = {Genetic parameters for meat yield and quality traits derived from the New Zealand Perendale progeny test}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {106-110}, address = {Dunedin}, abstract = { A catch phrase within animal genetics is that there is as much variation within a breed as there is between breeds. The New Zealand Perendale Progeny Test has been conducted on North and South Island sites since 2010 with the aim of investigating genetic variability for carcass traits. A total of 51 sires, from 27 studs have been assessed, with sires selected from the top 20\% of the Perendale across-flock Dual Purpose Index SIL evaluation. Within each year/site lambs generated were born within a week (ewes naturally synchronised pre-mating), and slaughtered on the same day. A total of 2318 male progeny have been generated and slaughtered through Alliance with traits measured including weight traits, carcass dimensions, VIAscan{\textregistered} traits, carcass pH, carcass fat colour and, in some years, colour stability of chilled aged loins, subjective marbling score and meat tenderness. Genetic parameters were estimated with ASREML; carcass weight was fitted as a co-variate for carcass traits (excluding carcass weight). The heritability estimates for all traits were moderate to high, with the lowest of 0.22 {\textpm} 0.07 for VIAscan{\textregistered} GR, and the highest, for pH, of 0.44 {\textpm} 0.09, with the majority between 0.22 and 0.43. The high estimate for slaughter plant measured pH was supported by the 0.59 {\textpm} 0.17 estimate for pH measured in the laboratory on those samples which were measured for colour stability. The phenotypic correlations between traits were generally well estimated with small standard errors for the majority of trait combinations. The genetic correlations were not as well estimated with standard errors greater than 0.10 for most traits combinations, but despite the large standard errors some were still significant, and in general agreement with values the literature. The progeny test has therefore demonstrated significant genetic variability for the range of carcass traits assessed in this study within the Perendale breed.}, issn = {1176-5283}, author = {PL Johnson and Young EA and Russenklau D and Anderson T and Dodds KG} } @conference {79012, title = {Development of a visual scoring system for ovine pneumonia at the processing plant}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {169-171}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Pneumonia in sheep is a consequence of multiple infectious agents compromising the host{\textquoteright}s immune system, often with the aid of environmental factors. Chronic non-progressive pneumonia (CNP) and acute fibrinous pneumonia (AP) are the main concerns to the New Zealand sheep industry. AP occurs in sheep of all ages and is more common in older lambs during the late summer early autumn period. CNP is often seen in lambs aged between five and ten months of age. Clinical diagnosis is difficult with affected lambs showing few, if any, clinical signs of illness as reviewed by (Alley 2002). Accurate diagnosis requires examination of the lung. ... continued}, issn = {1176-5283}, author = {Baird HJ and Clarke SM and PL Johnson} } @conference {79017, title = {Estimates of genetic parameters for flystrike in New Zealand Romney and Romney cross sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {189-191}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {

Myiasis, or flystrike, is a major animal welfare problem for sheep that causes significant production losses and potentially death. It is estimated that the prevalence of flystrike is 3-5\% in the national flock (Heath \& Bishop 1995) and is estimated to cost the New Zealand industry $40 to $50 million annually (Beef + Lamb New Zealand 1999). These costs accrue via production losses through reduced wool and body growth, morbidity, and control strategy costs including insecticide, lamb shearing and crutching. ... continued

}, issn = {1176-5283}, author = {Pickering NK and Dodds KG and Blair HT and Hickson RE and PL Johnson and McEwan JC} } @conference {69487, title = {Carcass linear measurements as predictors of meat yield in lambs determined by VIAscan}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {130-132}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Lambs yielding proportionally more lean meat are desirable to processing companies as they have a greater quantity of saleable product which also meets market demand withoutthe need for further processing. The quest for higher yielding lean lambs has seen a change in the lamb carcass grading system from classification on carcass weight and the GR measurement (total tissue depth above the 12th rib, 110 mm from the midline) (Kirton, 1989) to using imaging systems such as VIAscan{\textregistered}. VIAscan{\textregistered} is a two dimensional imaging system that estimates lean content of the carcass (Hopkins et al., 2004).}, issn = {1176-5283}, author = {Bain WE and McEwan JC and McLean NJ and PL Johnson} } @conference {69486, title = {Determining taste panel traits which contribute to the overall liking of New Zealand lamb as assessed by a British sensory panel}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {127-129}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {New Zealand is the world{\textquoteright}s largest exporter of sheep meat with the United Kingdom being the single largest market (Meat \& Wool New Zealand, 2009). Hence, the acceptance of sheep meat in international markets is an important economic issue (Prescott et al.2001). For retail purchasers of meat in the United Kingdom the visual appearance, the eating experience, and their interaction will influence how much the consumer is willing to pay for the product (Savellet al., 1989). To ensure repeat purchases of high quality New Zealand lamb by United Kingdom consumers, it is important that the consumer enjoys the overall eating experience of the product.}, issn = {1176-5283}, author = {McLean NJ and PL Johnson and Charteris A} } @conference {60952, title = {Effect of sex on colour and pH of chilled lamb loins : Brief Communication}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {101-103}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {With more chilled lamb being exported from New Zealand, there is interest in factors affecting the quality of the chilled product. Two key factors are ultimate pH and the redness of the meat when on display for sale. The possible effect of the sex of the lamb on these quality traits is of interest to the industry (Meat and Wool New Zealand, 2006). A number of studies have reported non-significant differences between ewe and ram lambs at moderate carcass weights of approximately 18 kg, for pH and colour measured within 24 hours post-slaughter... Continued }, issn = {1176-5283}, author = {Bain WE and McLean NJ and Young EA and PL Johnson} } @conference {60980, title = {Genetic parameters for colour stability of chilled lamb : Brief Communication}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {220-222}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {An increasing proportion of New Zealand lamb meat is shipped to the European Union market as chilled rather than frozen product, with 29\% exported as chilled product in 2005/06 (Meat and Wool New Zealand, 2006). New Zealand{\textquoteright}s lamb export markets are located such that the chilled product travels large geographical distances via freighted shipping, taking six to twelve weeks to reach the destination. Once chilled lambs arrives at its destination it is further processed and packaged to specification for retail sale. Shelf life and colour stability are particularly important for this... Continued }, issn = {1176-5283}, author = {McLean NJ and PL Johnson and Bain WE and Greer GJ and Dodds KG} } @conference {60953, title = {Investigating marbling and its relationship to meat quality in New Zealand pasture fed lamb}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {69}, year = {2009}, month = {Jun}, pages = {104-107}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {This is the first report of marbling in New Zealand pasture finished lamb. Marbling and meat quality data were collected on 1,056 loins from pasture finished lambs. Marbling was subjectively assessed on loin cut surfaces, using a five point visual scale (1 = Low, 5 = High), and objectively assessed using computer tomography (CT) scanning. Tenderness was objectively measured on loins that had been frozen. Corresponding loins from the lambs with the fifty highest (High) and fifty lowest (Low) subjective marbling scores were taste panelled after chilled storage. The average subjective scores were 2.94 and 0.94 for the High and Low groups respectively, with the objectively measured CT fat percentages 8.0\% and 10.0\% respectively, both significant differences (P <0.001). Loins from the High group were significantly (P <0.01) more tender than loins from the Low group as assessed objectively, however, this difference was not detected by the taste panel when assessing texture. The taste panel did not detect any significant differences in juiciness, flavour or odour between the two groups. Our findings suggest that this level of marbling in pasture fed, New Zealand chilled stored lamb is insufficient to influence meat quality as assessed by a taste panel. }, issn = {1176-5283}, author = {Young EA and Bain WE and McLean NJ and Campbell AW and PL Johnson} } @conference {41785, title = {Effect of MyoMAX on carcass lean and fat}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {68}, year = {2008}, month = {Jan}, pages = {43-44}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Brisbane, Australia}, abstract = {Previous research has identified quantitative trait loci (QTL) for increased lean meat yield and decreased fat in similar regions of sheep chromosome 2, in New Zealand and Belgian Texels (Broad et al., 2000; Johnson et al., 2005; Laville et al., 2004; Marcq et al., 2002). In the case of the Belgian Texels it has been demonstrated that a single G to A transition ...Continued }, issn = {1176-5283}, author = {Bain WE and PL Johnson and Greer GJ and Dodds KG and McLean NJ and McLaren RJ and Galloway SM and Van Stijn TC and McEwan JC} } @conference {41819, title = {Factors affecting colour stability of fresh chilled lamb meat}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {68}, year = {2008}, month = {Jan}, pages = {164-165}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Brisbane, Australia}, abstract = {An increasing proportion of New Zealand lamb meat is shipped to the European Union market as chilled rather than frozen product, with 29\% exported as chilled product in 2005/06 (Anon, 2006). Once chilled lamb reaches this market it is further processed, with the lamb meat entering the retail market approximately eight weeks after slaughter. A major selection criterion for retail purchasers is the colour of the meat on display. Most consumers prefer bright red ...Continued }, issn = {1176-5283}, author = {PL Johnson and McLean NJ and Bain WE and Young E and Campbell AW} } @conference {41719, title = {Current status of QTL and association studies in New Zealand cattle , sheep and deer}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {153-159}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {In the last 15 years, a series of experiments has beencarried out to search for quantitative trait loci (QTL) in New Zealand cattle, sheepand deer. A QTL represents the position on a chromosome where there is a statistically significant genetic effecton a measured trait. This paper reviews data published so far from these QTL trials and from various association studies. Although the measurement of traits (or {\textquoteleft}phenotypes{\textquoteright}) and the sampling of tissue or fluid for DNA may be complete, the genotyping of DNA isstill incomplete in most studies; further work may be expected as new DNA genotyping techniques and new genomic data become available, and as funds allow. In cattle, we describe the current status of research for carcass composition, meat quality, pubertal traits, milk yield and milk composition traits, and resistance to facial eczema and bloat. In sheep, we include QTL searches for disease traits (resistance to nematode parasites, facial eczema, ryegrass staggers, and footrot), muscling and carcass composition, reproductive traits, wool traits, and lamb survival. In deer, QTL searches have been carried out for live weights, seasonality and pubertal traits, using measurements from an interspecific hybrid. Generally, significant results have been followed further by finemapping and independent validation, before release to industry. Some of the mapping techniques will be described, with examples. So far, QTLs under study in New Zealand have led to the identification and use of gene-tests or marker-tests for meat tenderness and carcass composition in beef cattle, milk yield and composition traits in dairy cattle, and meat yield \%, muscling and litter size genes in sheep.}, issn = {1176-5283}, author = {Morris CA and Campbell AW and Cullen NG and Davis GH and Everett-Hincks JM and Hall RJ and Henry HM and PL Johnson and McEwan JC and Phua SH and Wilson T} } @conference {41699, title = {To wether - short scrotum or leave lambs as entire rams ? Revisiting an old question using new genetics}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {44-47}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {A comparison of wethers (WTH), short scrotum (SSC) and rams (RAM) was made on 552 7/16 Romney, 3/16 Poll Dorset, 3/16 Texel and 3/16 East Friesianlambs. Lambs were drafted for slaughter using commercial criteria on weight and condition score at weaning (D81), D120, D154 and D192. Due to faster growth rates, by the end of the 2nd kill (D120) approximately 31\% of RAM and SSC lambs were slaughtered compared with 16\% of WTH lambs (P<0.01), although the difference was no longer significant by the end of the 4 th kill. The carcass weight of WTH (17.6kg) was significantly heavier (P<0.01)than the RAM (17.2kg) but not significantly different to the SSC (17.5kg), despite similar kill liveweights, due to the increased dressing out percentages of the WTH lambs (43.6\%, 43.1\% and 42.5\% respectively; P<0.05). Based on GR, 8.7\% of WTH carcasses graded overfat, compared with only 0.6\% of RAM and SSC carcasses (P<0.001). Over the kill period the price schedule ($/kg carcass weight) dropped, so for the WTH given their longer time to slaughter and poorer grading due to over fat carcasses the price for WTH carcasses ($49.16) was lower (P<0.01) than RAM or SSC carcasses ($50.37 and $50.70). When the added cost of feeding and drenching was taken into consideration, the net value of the WTH was evenless. Composite wether lambs of still potentially present an opportunity cost, except incertain situations where the management benefits outweigh the direct financial cost. }, issn = {1176-5283}, author = {PL Johnson and Kenyon PR and Burnham DL and West DM} } @conference {41827, title = {Effect of slaughter group and sire on carcass composition and meat quality characteristics of Texel-sired lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {241-246}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {New Zealand meat companies are investigating lamb payment systems based on lean-meat yield and meat quality. Factors that affect these traits need to be determined. Carcass composition and meat quality data from 450 Texel-cross lambs (ewe and ram) were used to evaluate the effect of sire (two sires Property One, three sires Property Two) and slaughter group. Lambs reaching target slaughter weight first (38 kg and 35 kg for ram and ewe lambs respectively) were allocated to slaughter group one, with the remainder allocated to slaughter group two and slaughtered approximately 40 days later. The average carcass weight for both groups was 17.9 {\textpm} 1.51 kg. Carcass composition traits were adjusted for carcass weight, and meat quality traits were adjusted for pH. Carcass width at the thorax and gigot was narrower in slaughter group two (P < 0.001). Trimmed leg weight and total leg muscle weight were lower (P < 0.001), whereas total leg fat weight and muscle to bone ratios were higher (P < 0.001), for slaughter group two. Femur muscularity was higher in slaughter group two (P < 0.001) for Property One only. Warner-Bratzler shear values and measures of colour (L*, a* and b*) were higher (P < 0.001), whereas cooking loss was lower (P < 0.001), for the longissimus muscle in slaughter group two. In addition, sire within property was a source of variation (P < 0.001) for all carcass composition traits and meat quality traits, with the exception of pH. These results demonstrate that both slaughter group and sire (within a breed and property) are significant sources of variation in carcass composition and meat quality traits. As a result, these need to be taken into account when making management and breeding decisions for the supply of lambs to meat companies under any future payment systems based on yield and meat quality. KEYWORDS: lamb; carcass traits; sire. }, issn = {1176-5283}, author = {PL Johnson and Purchas RW and Blair HT} } @conference {41345, title = {Ranking Romney sires on carcass value from a progeny test}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {183-187}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Interest in the meat-producing potential of rams of dual-purpose breeds such as the Romney has increased in recent years. To cater for this a group of Manawatu ram breeders have established a progeny test to determine sire differences in carcass value (CV) estimated as the sum of the value of individual carcass parts. In 2000-2001, detailed information was collected on 139 carcasses representing 12 sires. The average carcass weight and CV ({\textpm} sd) were 14.9 {\textpm} 1.9kg and $81.76 {\textpm} $10.76 respectively. A stepwise regression model with residual CV as the dependent variable was used to determine whether sire rankings on CV could be satisfactorily achieved by weighing only selected carcass parts. Weight of boneless leg (BL) explained the most variation with an r2 of 0.84. The addition of the weights of the frenched rack (FR) striploin (ST) each significantly (P<0.001) increased the amount of variation explained (r2 = 0.90), and increased the rank correlation between estimated and actual sire-group rankings from 0.71 to 0.95. A minimal model to rank the sires in this Romney progeny test is CV= -72.06+30.42*FR + 24.39*ST + 12.36*BL. Use of this model would avoid incurring the costs of weighing all carcass parts. }, issn = {1176-5283}, author = {PL Johnson and Purchas RW and Blair HT} }