Australian Journal of Experimental Agriculture最新文献

{"title":"Metabolic profile and oxidative status in goats during the peripartum period","authors":"P. Celi, A. Trana, A. Quaranta","doi":"10.1071/EA07410","DOIUrl":"https://doi.org/10.1071/EA07410","url":null,"abstract":"The aim of this study was to monitor the metabolic profile and oxidative status in goats during the peripartum period. A blood sample was taken from 10 Red Syrian goats on days −21, −3, +1, +14, and +28 from delivery. Samples were assayed for glutathione peroxidase and superoxide dismutase activities, and reactive oxygen metabolites, insulin, insulin-like growth factor-I, free triiodothyronine (fT3), free thyroxine (fT4), leptin, urea, non-esterified fatty acids, triglycerides, cholesterol, total protein, albumin, globulin, calcium and inorganic phosphorus concentrations. Blood glutathione peroxidase activity decreased during the postpartum period and its values were significantly (P < 0.05) lower on days 14 and 28 postpartum. Albumin levels were significantly (P < 0.05) lower on days −3, 1 and 28 from delivery compared with day −21. Plasma urea levels significantly (P < 0.001) decreased starting from day −3 from delivery. No effect of time from delivery was noted on reactive oxygen metabolites, non-esterified fatty acids, triglycerides, cholesterol, total protein, calcium and inorganic phosphorus, insulin and leptin concentrations and superoxide dismutase activity. Plasma concentrations of fT3 were significantly (P < 0.01) higher on days 14 and 28 compared with days −21, −3 and 1 from delivery. Plasma levels of fT4 were significantly (P < 0.01) lower on days −3 and 1 from delivery. Plasma insulin-like growth factor-I values slowly decreased during the postpartum period and its values were significantly (P < 0.05) lower on day 28. This study indicates that goats experienced moderate oxidative stress during the peripartum period.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1004-1008"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07410","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58798800","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":"Linking rumen function to animal response by application of metagenomics techniques","authors":"J. Firkins, S. Karnati, Zhongtang Yu","doi":"10.1071/EA08028","DOIUrl":"https://doi.org/10.1071/EA08028","url":null,"abstract":"Metagenomics techniques applied to the rumen microbiota have demonstrated tremendous diversity originally among populations of bacteria and, more recently, among the methanogenic archaea, including those associated with protozoa. Although with some potential limitations, cluster analyses of sequences recovered from clone libraries have revealed differences in populations among animals fed forage v. grain, including amylolytic ruminococci and novel groups of clostridia adhering to the rumen particulates. Rapid profiling procedures, such as denaturing gradient gel electrophoresis (DGGE), can be used to infer likely differences in community structure of bacteria and archaea among numerous replicates of animals and times after feeding diets that are more representative of intense ruminant animal production. Metagenomics procedures also are being applied to issues related to ruminal output of fatty acid isomers influencing milk fat composition and consumer acceptance, the environmental impact of nitrogen in animal waste and methane emissions, and future potential approaches to improve ruminal fibre digestibility. If varying concentrations of ruminal metabolites and fluxes quantified from microbial processes can be combined with results from metagenomics applied to rumen microbiota, then we should reduce the unexplained variability in models in which the prediction of nutrient supply to the intestine is synchronised with nutritional guidelines for more efficient feed conversion by ruminants.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"711-721"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58802184","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":"Improving calf survival and performance by supplementation in Bali cattle","authors":"I. Jelantik, M. Mullik, C. L. Leo-Penu, J. Jeremias, R. Copland","doi":"10.1071/EA08038","DOIUrl":"https://doi.org/10.1071/EA08038","url":null,"abstract":"An on-farm experiment was conducted in several villages in the district of Kupang, East Nusa Tenggara Province (NTT), Indonesia from June to October 2007. The experiment investigated the efficacy of a supplementation strategy to improve calf survival and performance during the dry season. A total of 258 Bali (Banteng, Bos javanicus) cow-calf pairs were used in the experiment. Calves from the 190 cow-calf pairs in the treatment groups were allocated grass hay + concentrate supplementation as follows: 1% (n = 98), 2% (n = 56) and 3% (n = 42) of calf bodyweight. There were 62 cow-calf pairs in the unsupplemented control group. The supplement consisted of grass hay and concentrate (rice bran, cornmeal, leucaena leaf and fish meal) containing 18% crude protein. The supplement was introduced to calves in the morning while confined to calf pens when the dams were grazing. Calves were reunited with the cows during the night. Parameters measured were calf mortality, calf and cow daily gain, and milk production. Supplementation tended to reduce calf mortality (P = 0.094) from 6.4% in control to 0% in calves receiving 2% and 3% supplement. Levels of supplementation significantly (P < 0.001) improved calf daily weight gain. Bodyweight changes and milk production of cows were unaffected by calf supplementation. It can be concluded that supplementation at 2% calf bodyweight reduces calf mortality and improves calf weight gain.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"17 1","pages":"954-956"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58802914","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":"Diversity of methanogens in ruminants in Queensland","authors":"D. Ouwerkerk, A. F. Turner, A. Klieve","doi":"10.1071/EA08049","DOIUrl":"https://doi.org/10.1071/EA08049","url":null,"abstract":"Methane emissions from ruminant livestock represent a loss of carbon during feed conversion, which has implications for both animal productivity and the environment because this gas is considered to be one of the more potent forms of greenhouses gases contributing to global warming. Many strategies to reduce emissions are targeting the methanogens that inhabit the rumen, but such an approach can only be successful if it targets all the major groups of ruminant methanogens. Therefore, a thorough knowledge of the diversity of these microbes in different breeds of cattle and sheep, as well as in response to different diets, is required. A study was undertaken using the molecular techniques denaturing gradient gel electrophoresis, DNA cloning and DNA sequence analysis to define the extent of diversity among methanogens in ruminants, particularly Bos indicus cross cattle, on differing forages in Queensland. It was found that the diversity of methanogens in forage-fed cattle in Queensland was greater than in grain-fed cattle but there was little variability in methanogen community composition between cattle fed different forages. The species that dominate the rumen microbial communities of B. indicus cross cattle are from the genus Methanobrevibacter, although rumen-fluid inoculated digestors fed Leucaena leucocephala leaf were populated with Methanosphaera-like strains, with the Methanobrevibacter-like strains displaced. If ruminant methane emissions are to be reduced, then antimethanogen bioactives that target both broad groups of ruminant methanogens are most likely to be needed, and as a part of an integrated suite of approaches that redirect rumen fermentation towards other more useful end products.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"722-725"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08049","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58803026","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":"Approaches for assessing some attributes of feed-base systems in mixed farming enterprises","authors":"L. Bell, M. Robertson, D. Revell, J. Lilley, A. Moore","doi":"10.1071/EA07421","DOIUrl":"https://doi.org/10.1071/EA07421","url":null,"abstract":"Improving the feed-base to better balance livestock demands with the variation in feed supply can improve the sustainability and productivity of livestock enterprises. This paper outlines some approaches and tools that can be applied to the assessment of new feed options and/or potential changes to the feed-base in mixed farming systems. Demonstrations of strategic aspects of designing feed systems include: whole-farm feed planning using simple tools, such as the MLA Feed Demand Calculator, that enable iterative changes to the balance between feed supply and demand to be considered simultaneously; assessing production and environmental risks of different feed-base systems using simulation models (e.g. APSIM, GRAZPLAN); and using bio-economic models (e.g. MIDAS) to investigate the impact of a new feed source on whole-farm profitability and the optimal balance of other feed sources and livestock production system. Also included is an example of an approach to identifying opportunities and seasonal triggers for a tactical response for utilising an alternate feed source (e.g. grazing a grain crop). The importance of economics and risk as factors for assessing feed-base systems is demonstrated. In particular, the marginal value of extra feed supply is a critical element driving the whole-farm economics of the feed system. Some approaches consider seasonal averages, but the risk of year-to-year and within-year variations in the timing and amount of feed supply should also be assessed. Several tools of varying complexity exist to investigate attributes of the feed-base, but it is important that the correct approach is applied to the particular question in mind. A range of approaches could be applied concurrently to fully explore a range of aspects of the performance of a feed-base system.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"789-798"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07421","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58799966","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":"Effect of whole cottonseed supplementation on energy and nitrogen partitioning and rumen function in dairy cattle on a forage and cereal grain diet","authors":"C. Grainger, T. Clarke, R. Eckard","doi":"10.1071/EA07400","DOIUrl":"https://doi.org/10.1071/EA07400","url":null,"abstract":"The experimental objective was to determine the effect of adding whole cottonseed (WCS) to a forage and cereal grain diet on the energy and nitrogen balance and rumen function of lactating dairy cattle. Two experiments were carried out, a field experiment and an indoor metabolism experiment. In the field experiment, 50 lactating cows ~200 days in milk were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (morning) and ryegrass-based pasture silage (afternoon) in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg dry matter (DM)/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of WCS with their grain supplement. Samples of rumen fluid were collected from each fistula, ~4 h after grain feeding in the morning, of eight cows (four per group) on 1 day in each of the 5 weeks of treatment. In the metabolism experiment, immediately after the 5 weeks of feeding, 12 lactating cows, six from each treatment from the field experiment, were randomly selected and individually housed in metabolism stalls and fed the same diets for a 6-day energy and nitrogen balance study. Cows were fed at milking times (0700 and 1530 hours) and all feed offered and refused was weighed daily. All cows were offered 5.6 kg DM/cow.day of pasture silage, 4 kg DM/cow.day of lucerne hay and 3 kg DM/cow.day of cereal grain. In addition, cows in the WCS treatment group were offered 2.7 kg DM/cow.day of WCS with their grain supplement. In the metabolism study, adding WCS to the diet resulted in a greater energy intake, but there was no depression in energy digestibility. Whole cottonseed also increased nitrogen intake and nitrogen digestibility of the diet was increased from 62 to 75%, but the proportion of nitrogen in milk remained the same with a greater proportion of nitrogen appearing in body tissue. In the field experiment, supplementation with WCS did not alter rumen fluid ammonia-N or volatile fatty acid concentrations. Adding WCS did not affect three of the main classes of protozoa, based on size, within the two major orders of ciliate protozoa. The WCS did, however, reduce the levels of entodiniomorphs >200 µm diameter and holotrichs < 200 µm diameter, but these only account for a small number of the total protozoa present. Supplementation of a forage and grain-based diet with WCS improved the energy and protein content of the diet without any negative effects on rumen digestion and with a similar proportion of dietary energy and nitrogen appearing in milk. Over the summer period in winter-rainfall dairying areas in south-east Australia when pasture availability is limited and the diet is mainly comprised of forage and cereal grain fed at a level that is energy-limiting for maximum production, WCS can be and is used to supplement the diet to imp","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"860-865"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07400","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58798480","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":"Higher weaning weight improves postweaning growth and survival in young Merino sheep","authors":"S. Hatcher, J. Eppleston, R. Graham, J. Mcdonald, S. Schlunke, B. Watt, K. Thornberry","doi":"10.1071/EA07407","DOIUrl":"https://doi.org/10.1071/EA07407","url":null,"abstract":"Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning weight was the most important factor in determining postweaning liveweight, growth rates and survival with the significant impact of weaning weight on liveweight persisting for up to 6 months after weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postweaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher weaning weights that will set their weaners up for strong postweaning growth with a decreased likelihood of mortality.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"966-973"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58799014","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":"Reduced space allowance for adult sheep in lairage for 24hours limits lying behaviour but not drinking behaviour","authors":"E. Jongman, M. K. Edge, K. Butler, G. Cronin","doi":"10.1071/EA08039","DOIUrl":"https://doi.org/10.1071/EA08039","url":null,"abstract":"The key lairage requirements for livestock include sufficient space to lie down, sufficient time to allow recovery from travel, and access to water to allow recovery from dehydration. Current recommendations for lairage of adult sheep include that holding pens should provide no less space than 0.6 m2 per sheep. Particularly during periods when large numbers of sheep are culled, space allowances may be limited to 0.3 m2 or less, which may reduce the ability of individual sheep to lie down or access water. Adult Merino-cross sheep were allocated to one of four space allowance treatments during unloading from commercial transport vehicles at a commercial abattoir after an average transport time of 3 h. The treatments were 0.3, 0.45, 0.6 and 1.0 m2/sheep and each pen measured 18 m2. Differences in space allowance were achieved by varying the number of sheep per pen, with pens holding 18 (1 m2), 30 (0.6 m2), 40 (0.45 m2) and 60 (0.3 m2) animals. In each pen, eight focal sheep were randomly selected and marked on the back for identification on video records. The sheep remained in the lairage treatments for 24 h and were continuously recorded on video using low light cameras. The data were subsequently analysed for both lying and drinking behaviours after 8 and 24 h in lairage. There were five replicates of all treatments over a 3-week period. A space allowance of 0.3 m2/sheep reduced the time sheep spent lying and the proportion of sheep that lay down at least once, compared with greater space allowances. Space allowances between 0.3 and 1 m2/sheep showed a linear relationship with the time sheep spent lying during the first 24 h. Optimal space allowance may be greater than 1 m2, based on lying behaviour. Drinking behaviour was not affected by space allowance in a 24 h period in lairage although overall 20% of sheep were not observed to drink after 24 h in lairage.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1048-1051"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58803002","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":"Heifer fertility on commercial cattle properties in the Northern Territory","authors":"T. Schatz, M. Hearnden","doi":"10.1071/EA08057","DOIUrl":"https://doi.org/10.1071/EA08057","url":null,"abstract":"The performance of heifers at their first (maiden heifers) and second matings (first lactation heifers) was recorded between 2003 and 2008 to establish current heifer fertility levels on 14 commercial cattle properties in the Northern Territory (NT). Pregnancy rates in maiden heifers (joined first at ~2 years of age) were generally adequate (>75%) to produce enough pregnant replacement breeders. Pregnancy rates in first lactation heifers were often very low ( 70%). Calf loss between pregnancy diagnosis and weaning in first lactation heifers was often high (>30%). The average of the calf loss figures from all the herds studied was 22%.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"940-944"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58803719","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":"Intramuscular fat levels in sheep muscle during growth","authors":"M. McPhee, D. Hopkins, D. Pethick","doi":"10.1071/EA08046","DOIUrl":"https://doi.org/10.1071/EA08046","url":null,"abstract":"A5 ·4 factorial experiment was designed in which lambs representing five genotypes were slaughtered at four ages (110, 236, 412 and 662 days of age). The genotypes represented were Poll Dorsetgrowth ·Border Leicester Merino, Poll Dorsetgrowth ·Merino, Poll Dorsetmuscling ·Merino, Merino ·Merino and Border Leicester ·Merino. Both sexes (ewes and wethers) were represented for each genotype and slaughter age combination. In total, 595 animals were slaughtered and the carcass composition and intramuscular fat were measured. Carcass composition (fat, ash and protein (lean)) was determined by dual energy X-ray absorptiometry, with the intramuscular fat percentage determined using near- infrared spectroscopy following removal and weighing of the entire longissimus thoracis et lumborum (LL) muscle. Analysis revealed that the proportion of intramusular fat in the loin relative to total carcass fat decreases as animals mature, thus indicating that intramusular fat deposition occurs early in the maturation of sheep. Furthermore, as animals became heavier and older the accretion rate of intramuscular fat in the LL muscle slowed down. Both genotype (P < 0.05) and sex (P < 0.001) were found to impact on this pattern, with Border Leicester ·Merino animals exhibiting the largest increase in intramuscular fat proportion in the LL muscle (4.92 and 5.50% at 22 months of age for ewes and wethers, respectively). The Poll Dorsetgrowth ·Border Leicester Merino animals were found to have the greatest absolute levels of intramuscular fat in the whole LL muscle (80.95 and 97.60g at maturity for ewes and wethers, respectively). The amount of intramuscular fat significantly increased as the sheep became older and fatter; however, these differences were quantitatively small. As such, finishing prime lambs to high levels of total carcass fatness would have little effect on any eating quality benefits associated with increased intramuscular fat proportion.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"8 1","pages":"904-909"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08046","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58802932","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}