Farming, New Zealand
Farming, New Zealand

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Griffiths A.G.,Agresearch Ltd. | Barrett B.A.,Agresearch Ltd. | Simon D.,Landcorp Farming Ltd | Khan A.K.,Agresearch Ltd. | And 5 more authors.
BMC Genomics | Year: 2013

Background: White clover (Trifolium repens L.) is a temperate forage legume with an allotetraploid genome (2n=4×=32) estimated at 1093 Mb. Several linkage maps of various sizes, marker sources and completeness are available, however, no integrated map and marker set has explored consistency of linkage analysis among unrelated mapping populations. Such integrative analysis requires tools for homoeologue matching among populations. Development of these tools provides for a consistent framework map of the white clover genome, and facilitates in silico alignment with the model forage legume, Medicago truncatula.Results: This is the first report of integration of independent linkage maps in white clover, and adds to the literature on methyl filtered GeneThresher®-derived microsatellite (simple sequence repeat; SSR) markers for linkage mapping. Gene-targeted SSR markers were discovered in a GeneThresher® (TrGT) methyl-filtered database of 364,539 sequences, which yielded 15,647 SSR arrays. Primers were designed for 4,038 arrays and of these, 465 TrGT-SSR markers were used for parental consensus genetic linkage analysis in an F1 mapping population (MP2). This was merged with an EST-SSR consensus genetic map of an independent population (MP1), using markers to match homoeologues and develop a multi-population integrated map of the white clover genome. This integrated map (IM) includes 1109 loci based on 804 SSRs over 1274 cM, covering 97% of the genome at a moderate density of one locus per 1.2 cM. Eighteen candidate genes and one morphological marker were also placed on the IM. Despite being derived from disparate populations and marker sources, the component maps and the derived IM had consistent representations of the white clover genome for marker order and genetic length. In silico analysis at an E-value threshold of 1e-20 revealed substantial co-linearity with the Medicago truncatula genome, and indicates a translocation between T. repens groups 2 and 6 relative to M. truncatula.Conclusions: This integrated genetic linkage analysis provides a consistent and comprehensive linkage analysis of the white clover genome, with alignment to a model forage legume. Associated marker locus information, particularly the homoeologue-specific markers, offers a new resource for forage legume research to enable genetic analysis and improvement of this forage and grassland species. © 2013 Griffiths et al.; licensee BioMed Central Ltd.


Fisher M.W.,Kotare Bioethics | Muir P.D.,On Farm Research | Gregory N.G.,The Royal Veterinary College | Thomson B.C.,On Farm Research | And 3 more authors.
New Zealand Veterinary Journal | Year: 2015

Abstract: AIM: To determine the ability of sheep to mobilise their body reserves after being deprived of feed prior to transport for slaughter. METHODS: A total of 240 3- and 4-year-old cull ewes were held off pasture for 0, 9, 18 or 30 hours (n=60 per group) then transported 1 hour by road, unloaded and washed, held in lairage for 3 hours then slaughtered. Blood samples were collected from a subsample of 60 unfasted ewes 1 week earlier, and from all ewes at exsanguination to determine concentrations of serum metabolites indicative of adaptation to fasting. In addition, several attributes of carcass quality were measured. RESULTS: At slaughter, increased time off pasture prior to transport resulted in no change in glucose concentrations in serum (p=0.140). There were differences (p<0.001) between the group fasted for 30 compared with 0 hours in mean concentrations of free fatty acids (0.98 (SD 0.32) vs. 0.58 (SD 0.23) mmol/L), β-hydroxybutyrate (0.69 (SD 0.17) vs. 0.42 (SD 0.11) mmol/L), triglycerides (0.29 (min 0.13, max 0.83) vs. 0.22 (min 0.06, max 0.96) mmol/L) and urea (10.17 (SD 1.80) vs. 6.94 (SD 2.03) mmol/L). Different periods of feed deprivation had no effect (p>0.05) on carcass weights (mean 22.7, min 13.2, max 32.9 kg) or dressing out percentages (mean 40.9, min 27, max 49%). Meat ultimate pH was unaffected (p>0.05) by the period of feed deprivation but meat became darker (p<0.05) and had reduced redness (p<0.001) with increasing time off feed. CONCLUSIONS: The results suggest that sheep in variable body condition adapted to the periods of feed deprivation by mobilising their energy reserves without any evidence of metabolic depletion (e.g. depleted blood glucose or high meat pH). However, being deprived of feed they probably experience a degree of hunger. © 2015 New Zealand Veterinary Association.


Hickson R.E.,Massey University | Kenyon P.R.,Massey University | Blair H.T.,Massey University | Harding J.E.,University of Auckland | And 4 more authors.
Animal Production Science | Year: 2012

Thirteen-hundred and sixty-seven Romney mixed-aged ewes were randomly allocated to one of two liveweight gain treatments (high vs maintenance) from weaning of one litter of lambs until 71 days before the subsequent breeding (a period of 42 days). The aims of this study were first to determine whether ewe liveweight or liveweight gain treatment before rebreeding affected the number and liveweight of lambs produced and reared in the following season, and second, to identify whether the birth rank of the dam or the grand-dam affected the number, survival or liveweight of their lambs. Liveweight gain during the 42-day treatment period was greater (P<0.05) in the high than maintenance treatment (87±6 vs 4±6 g/day, respectively), although it did not influence (P>0.05) number of fetuses, lambs born or reared per ewe or total weight of lambs born or weaned per ewe. Ewe liveweight at weaning (113 days before rebreeding), and liveweight gain between the weaning and rebreeding, explained only a minor proportion of the variation in lamb liveweight at birth and weaning in the following season. Birth rank of the ewe or of the ewe's dam did not (P>0.05) influence liveweight or number of lambs born or weaned. In conclusion, this experiment indicated that liveweight and liveweight gain from weaning until rebreeding in the flock investigated had only a very minor influence on lamb production. Therefore, there appears to be little advantage in specifically managing ewes during this period to gain considerable amounts of liveweight. © 2012 CSIRO.

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