Australian Journal of Experimental Agriculture最新文献

{"title":"Simulation models used for determining food intake and growth of ostriches: an overview","authors":"R. Gous, T. Brand","doi":"10.1071/EA08137","DOIUrl":"https://doi.org/10.1071/EA08137","url":null,"abstract":"A formal method for determining the amino acid requirements of ostriches, from which a feeding strategy may be developed, requires characterisation of the growth potential of the body and feather proteins of these birds. Allometric equations may then be used to predict the growth of the physical parts of the ostrich, from which the optimal harvest time can be determined. Reasonable estimates of the parameters describing body and feather growth are now available. These values, together with the amino acid composition of the ostrich carcasses obtained at various stages of growth, make it possible to calculate the daily amino acid requirements of an ostrich growing at its potential. Subsequently, when given a description of the feed being offered, the desired food intake can be determined. The constraining effects of feed bulk and high temperatures are not yet well defined, but voluntary food intake in these birds when fed intensively under normal environmental conditions can now be predicted with the use of simulation models, from which it is possible to design a feeding strategy that will optimise performance.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1266-1269"},"PeriodicalIF":0.0,"publicationDate":"2008-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08137","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58805180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic relationships between water loss and shell deaths in ostrich eggs, assessed as traits of the female","authors":"Z. Brand, S. Cloete, I. Malecki, C. Brown","doi":"10.1071/EA08127","DOIUrl":"https://doi.org/10.1071/EA08127","url":null,"abstract":"The ostrich industry suffers from a high rate of embryonic mortality during artificial incubation of eggs. Data \u0000from 34285 eggs were used to derive 969 female-year records for evaporative water loss (WL), treated as a trait of the \u0000female. Heritability was significant for WL at a level of 0.40–0.41 (both after 21 and 35 days of incubation). WL at 21 and 35 days was negatively correlated on the genetic level with chick weight at hatching (–0.84 and –0.81, respectively). Shell deaths did not exhibit high levels of genetic variation (0.06), but were affected by the permanent environment of the female (0.33). Shell deaths were correlated with WL on a genetic level (–0.34 to –0.41), but the estimated genetic correlations were associated with high standard errors and are, therefore, not very robust. Further research is needed to obtain more \u0000accurate genetic relationships between traits influencing incubation.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"53 1","pages":"1326-1331"},"PeriodicalIF":0.0,"publicationDate":"2008-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08127","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58805300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial insemination technology for ratites: a review","authors":"I. Malecki, P. Rybnik, G. Martin","doi":"10.1071/EA08141","DOIUrl":"https://doi.org/10.1071/EA08141","url":null,"abstract":"In ratite farming, the low male to female ratio in the mating system restricts genetic improvement and prevents reduction of the number of males kept on-farm for fertilisation of the female flock. These issues can be overcome and the industry can better realise its potential by using artificial insemination (AI) technology. It is the only practical method for intensive genetic improvement of reproduction and the production of eggs, chicks, oil, meat and leather. For AI to be feasible, we need reliable methods for semen collection, artificial insemination, prolonged storage of spermatozoa in the female tract, high rates of lay, efficient protocols for semen storage, and a panel of quantitative methods for measuring true fertility and hatchability, sperm supply rates in vivo and sperm viability in vitro. For both emus and ostriches, prolonged sperm storage in females has already been demonstrated. Methods for semen collection and artificial insemination, using animal-friendly techniques, have also been developed. Semen storage and cryopreservation protocols are yet to be optimised and we still need to overcome the male-dependent rate of lay, but adoption of AI technology by the ratite industries is now feasible. It also seems likely that these technologies will be relevant to wild ratites that need intensive conservation efforts, such as cassowaries, rheas and ostrich subspecies.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"15 1","pages":"1284-1292"},"PeriodicalIF":0.0,"publicationDate":"2008-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08141","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58805793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Incomplete milking has no detectable effect on somatic cell count but increased cell count appears to increase strip yield","authors":"T. Clarke, E. Cuthbertson, R. Greenall, M. Hannah, D. Shoesmith","doi":"10.1071/EA07259","DOIUrl":"https://doi.org/10.1071/EA07259","url":null,"abstract":"Milking regimes that can greatly shorten the milking duration of slow-milking cows to improve labour productivity can also result in less complete milking for some cows. There is also a common belief and limited experimental evidence that incomplete milking of subclinically infected cows can cause increased somatic cell count (SCC). To test for this possible detrimental effect of shorter milking regimes, ‘complete’ milking [to automatic cluster remover (ACR) setting of 300 mL/min] and ‘incomplete’ milking (to an ACR setting of 800 mL/min) were applied sequentially to 45 cows over 7 weeks. Incomplete milking resulted in an average of 0.3 L of extra milk being left in the udders, but there was no significant increase in quarter SCC in either infected or uninfected udder quarters. Change in SCC was not related to change in strip yield induced by incomplete milking treatment. In contrast, cow strip yield was positively related to SCC, or the number of infected quarters/cow, regardless of the applied ACR treatment. These apparently contradictory findings are reconciled by noting that infection causes both high strip yields (via uneven yielding quarters) and high SCC. It is concluded that, contrary to popular belief, high SCC, as an indicator of infection, causes high strip yield and that increasing strip yield does not increase cell count.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1161-1167"},"PeriodicalIF":0.0,"publicationDate":"2008-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58795178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic parameters for yearling wool production, wool quality and bodyweight traits in fine wool Merino sheep","authors":"A. Swan, I. Purvis, L. Piper","doi":"10.1071/EA07425","DOIUrl":"https://doi.org/10.1071/EA07425","url":null,"abstract":"Genetic parameters were estimated for traits measured in the first year of production in a multi-bloodline flock of fine wool Merino sheep. Between 5025 and 9271 animals were measured, depending on the trait, and these animals were the progeny of up to 430 sires. Heritability estimates for fleece weight traits ranged from 0.37 to 0.49, while estimates for five wool quality traits ranged from 0.34 for staple strength to 0.66 for mean fibre diameter. For bodyweight, the heritability estimated at weaning was 0.20, and at the yearling age was 0.51. Maternal genetic effects were significant for fleece weight and bodyweight traits and were highly correlated between these trait groups, indicating that these effects are determined by similar groups of genes in both trait groups. While most genetic correlation estimates were either favourable or neutral, there were economically antagonistic correlations between fleece weight and mean fibre diameter, ranging from 0.15 to 0.30, and between mean fibre diameter and staple strength (0.26). Overall, the heritabilities and genetic correlations estimated in this fine wool population were similar to estimates from other strains, indicating that outcomes from selection programs will be similar across strains and that fine wool sheep can be included in across flock genetic evaluations with other strains.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1168-1176"},"PeriodicalIF":0.0,"publicationDate":"2008-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07425","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58799628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short- and long-range dispersal of the Queensland fruit fly, Bactrocera tryoni and its relevance to invasive potential, sterile insect technique and surveillance trapping","authors":"A. Meats, J. E. Edgerton","doi":"10.1071/EA07291","DOIUrl":"https://doi.org/10.1071/EA07291","url":null,"abstract":"Dispersal of immature and sexually mature Queensland fruit fly, Bactrocera tryoni (Froggatt) from releases made at a single point was assessed from recapture rates obtained by using arrays of traps. The recapture data (pertaining to distances up to 480 m) fitted both logarithmic and Cauchy models although the fits for the releases of immature flies were inferior because of high variability in catches at certain distances. When combined with data previously published for longer distances, a Cauchy model fitted data for releases of immature flies well and indicated that the median distance dispersed after emerging from the puparium was ~120 m and that 90% of flies would displace less than 800 m despite the fact that a consistent trend in declining catch rates can be obtained up to at least 85 km. This is consistent with the tail of the Cauchy distribution having a slope congruent with a negative power curve and thus being scale invariant for longer distances. The distribution of recaptured flies that were released as adults also fitted a Cauchy model with a tail of the same slope, suggesting that the spatial distribution of long-distance dispersers is not only scale invariant but also age invariant. This has significance to the ability of surveillance trapping arrays to detect infestations and also to methods of distributing insects for the sterile insect technique. Whereas the spread of invading propagules in the first generation is likely to be limited by a decline to non-viable density within 1 km or less of the incursion point, the influence of larger infestations on nearby uninfested regions would be limited by the longevity of the dispersers.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1237-1245"},"PeriodicalIF":0.0,"publicationDate":"2008-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07291","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58796948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emerging pest mites of grains (Balaustium medicagoense and Bryobia sp.) show high levels of tolerance to currently registered pesticides","authors":"Aston L. Arthur, A. Hoffmann, P. Umina, A. Weeks","doi":"10.1071/EA07181","DOIUrl":"https://doi.org/10.1071/EA07181","url":null,"abstract":"Balaustium medicagoense and Bryobia sp. (clover or pasture mite) have recently been identified as potential emerging pests of crops and pastures within southern Australia. Recorded damage by these mites has markedly increased in the past decade. There is limited information on the pesticide tolerance of these mites relative to other earth mite pests. This study examined the response of Ba. medicagoense and Bryobia sp., using the redlegged earth mite [Halotydeus destructor (Tucker)] as a comparison, to several currently registered pesticides against earth mites (omethoate, bifenthrin, chlorpyrifos, methidathion and α-cypermethrin). Ba. medicagoense had a much greater level of tolerance to all pesticides tested than H. destructor. Similarly, Bryobia sp. had a higher level of tolerance to bifenthrin, methidathion and α-cypermethrin than H. destructor. However, in the case of omethoate and chlorpyrifos, the tolerance levels were similar for Bryobia sp. and H. destructor. Ba. medicagoense had a higher level of tolerance than Bryobia sp. to the organophosphates tested (omethoate, chlorpyrifos and methidathion), but there was no difference for bifenthrin. We were unable to compare tolerance levels between Ba. medicagoense and Bryobia sp. to α-cypermethrin because of inconsistencies between replicate tests. These emerging pest mite species, therefore, have a high natural tolerance to currently registered pesticides and may prove difficult to control in the field. These findings suggest that other strategies that are not reliant on chemicals should be considered for the control of Ba. medicagoense and Bryobia sp.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1126-1132"},"PeriodicalIF":0.0,"publicationDate":"2008-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58793047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dissection of beef quality phenotypes using a myogenin network-anchored systems biology approach","authors":"A. Reverter, E. Chan, S. Lehnert, W. Barris, S. McWilliam, B. Dalrymple, W. Barendse","doi":"10.1071/EA08052","DOIUrl":"https://doi.org/10.1071/EA08052","url":null,"abstract":"In order to uncover genes with transcriptional activity linked to various beef quality phenotypes of interest, we designed a systems biology approach. We focussed on traits representing the three major categories of growth and development, fat depots and meat quality phenotypes. We proceeded by linking bovine gene expression data derived from 147 microarray hybridisation experiments and high density marker data from 9260 single nucleotide polymorphisms (SNP) on 189 steers. The individuals in the genotyping study were unrelated to the samples used for expression profiling. The linkage was performed by anchoring these data to a gene network for myogenin (MYOG), a muscle-specific transcription factor essential for the development of skeletal muscle. This approach was able to identify and estimate the strength of the relationship between the statistical association of a SNP to a phenotype of interest with the transcriptional activity of genes in the network. The genes from the MYOG-centred network that were significantly associated with the largest number of meat quality traits were PDLIM3, CALM1 and CRYAB. Among our findings, a novel association between desmin and meat colour points to an alternative biochemical basis for meat colour differences involving costameric structures and their previously reported relationship with tenderness. These newly generated hypotheses can help formulate sound research to further illuminate the genetic architecture of beef quality phenotypes.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1053-1061"},"PeriodicalIF":0.0,"publicationDate":"2008-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08052","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58803495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cashmere production and fleece attributes associated with farm of origin, age and sex of goat in Australia","authors":"B. McGregor, K. Butler","doi":"10.1071/EA06308","DOIUrl":"https://doi.org/10.1071/EA06308","url":null,"abstract":"Differences in cashmere production and fleece attributes associated with farm of origin, age and sex were quantified for commercial Australian cashmere goat enterprises. From 11 farms in four states, 1147 does and 97 wethers were monitored, representing 1- to 13-year-old goats. Individual clean cashmere production ranged from 21 to 389 g, with a mean ± standard deviation value of 134 ± 62 g. The mean cashmere production of 2-year-old does from different farms varied from 69 to 225 g and averaged 141 g. Mean ± s.d. greasy fleece weight was 394 ± 123 g, clean washing yield was 90.8 ± 4.1%, clean cashmere yield 33.4 ± 9.4%, cashmere fibre diameter 16.4 ± 1.6 µm, fibre curvature 48 ± 8.7 degrees/mm and staple length 8.7 ± 2.1 cm. There were large, commercially significant differences between farms for clean cashmere weight, mean fibre diameter and other attributes of cashmere. These were much larger than the effects of age and sex. Farm and age accounted for 42 to 67% of the variation in clean cashmere production, mean fibre diameter, fibre curvature, staple length and clean washing yield. Farm of origin affected clean cashmere yield, accounting for 24% of the variation. Sex of the goats had only a minor effect on the staple length of cashmere. The responses to age of clean cashmere weight, mean fibre diameter and the inverse of fibre curvature are very similar. Generally, cashmere production and mean fibre diameter increased with age. For the majority of farms, cashmere fibre curvature declined in a curvilinear manner with increases in age of goat. There were large differences in cashmere staple length from different farms, with means ranging from 7 to 12 cm. Between 1 and 2 years of age, the staple length of cashmere demonstrated a constant proportional increase. At ages older than 2 years, staple length either declined or increased by less than 1 cm with age, depending on the farm of origin. This study demonstrates that there are large gains in productivity that can be achieved from Australian cashmere goats. A better understanding of on-farm factors that influence cashmere production would enable all producers to optimise their production systems.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1090-1098"},"PeriodicalIF":0.0,"publicationDate":"2008-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA06308","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58788783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The occurrence and severity of grass toxicoses in Australian alpaca (Vicugna pacos) herds","authors":"Natália G. Sampaio, M. Gishen, K. Reed, Melessa Brown, D. Gregory, K. Munyard","doi":"10.1071/EA06325","DOIUrl":"https://doi.org/10.1071/EA06325","url":null,"abstract":"A survey of 108 alpaca producers registered with the Australian Alpaca Association examined the occurrence and severity of ‘staggers’ (a colloquial term embracing various diseases of the nervous system in animals, characterised by neck tremors and head nodding in the milder alpaca cases and a lack of coordination in moving, a staggering gait and frequent falling in severe cases) in Australian alpaca and the presence of four pasture grasses, during three production seasons in 2004–2006. There have been few studies on the susceptibility of alpaca to staggers and its effect on productivity and animal welfare. The survey found that 23% of alpaca producers had observed staggering animals, with Victoria and South Australia being the most severely affected states. Clinical signs of staggers were most frequent in January–March, with a mean duration of 3 months. Some animals showed clinical signs lasting up to 12 months. A strong correlation was found between the presence of perennial ryegrass (P < 0.001) and phalaris (P < 0.003) and the occurrence of staggers. Based on grass presence and the timing when staggers was observed, it was concluded that perennial ryegrass toxicosis was the main cause of staggers in alpaca. About 12% and 9% of alpaca grazing pasture containing perennial ryegrass exhibited staggers in the two full seasons for which data were collected. Herds with staggering animals were correlated with those exhibiting possible subclinical effects – heat sensitivity and ill-thrift (P < 0.01) and reduced fertility (P < 0.05) – of perennial ryegrass endophyte toxins. Results indicate that weanlings and cria are more likely to stagger than adults. Thirteen of the 15 mixed farms with staggering alpaca did not observe staggers in other livestock, suggesting that alpaca may be more sensitive to the causal toxins than sheep and cattle.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"57 1","pages":"1099-1104"},"PeriodicalIF":0.0,"publicationDate":"2008-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58789303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}