@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 = {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}
}
@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 = {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: 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 {41676,
	title = {An evaluation of sheep meat genetics in New Zealand: The central progeny test (CPT)},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {368-372},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {The New Zealand Central Progeny Test (CPT) was first established in 2001 with the aims of improving the carcass dollar value of sires and establishing genetic links among sire referencing schemes. Over the past three seasons, a total of 72 sires from both terminal and dual purpose breeds have been evaluated for meat genetics at the AgResearch Woodlands farm and the Lincoln University Ashley Dene farm. All progeny, except the 2004 born ewe progeny from the dual purpose sires, were slaughtered at monthly intervals from December to March each year through two Alliance plants, at threshold liveweights of 34kg. Carcass measurements included cut yield (measured by ViaScan grading) eye muscle area, GR, meat pH, meat and fat colour and days to reach an 18kg carcass weight. These measurements were used to calculate three key indices; days to kill, meat value and a combined meat and growth index, as well as individual breeding values. Results showed significant variation among sires for all key traits and that no single ram or breed dominated the top of the indices or breeding values. The range of economic value was approximately $10 across the terminal and dual purpose sires evaluated, demonstrating that considerable potential exists to identify and select better terminal sires. The CPT is now commencing maternal evaluation, using the retained ewe lambs produced from the dual purpose sires. },
	issn = {1176-5283},
	author = {McLean NJ and Jopson NB and Campbell AW and Knowler K and Behrent M and Cruickshank G and Logan CM and Muir PD and Wilson T and McEwan JC}
}
@conference {41439,
	title = {The Alliance Central Progeny Test: Preliminary results and future directions},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {197-200},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {The Alliance Central Progeny Test (CPT) was established in 2001 with the aims of improving the carcass dollar value of sires under the Alliance grading system and establishing links among ram breeders so Alliance can identify the best rams for their clients.  In the 2002/2003 season 22 terminal sires from nine different breeds were evaluated.   Each ram was mated to 30 ewes at the AgResearch Woodlands research farm.  Progeny numbers for each ram ranged from 13-46.   Initial early results showed that breeding values for weaning weight were well spread among sires (range over 2.5 kg) indicating there were genetic differences among sires used.  Lambs were slaughtered in four slaughter groups between December 16th , 2002 and March 11th , 2003.  Analyses from the full data set will be available from May 2003. The next cycle of the Alliance CPT begins with mating in April, 2003, with an emphasis on dual-purpose sires.},
	issn = {1176-5283},
	author = {Campbell AW and Knowler K and Behrent M and Jopson NB and Cruickshank G and McEwan JC and Wilson T}
}
