Natália G. Sampaio, M. Gishen, K. Reed, Melessa Brown, D. Gregory, K. Munyard
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.
{"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}
S. Pelletier, R. Simpson, R. Culvenor, G. Bélanger, G. Tremblay, G. Allard, J. Braschkat, P. Randall
The difference between cation and anion concentrations is an important property when assessing feed for dry dairy cows in order to avoid hypocalcaemia following calving. Dietary cation–anion difference (DCAD) is used to assess suitability of feed and predict the risk of milk fever; a value of –5 cmol(+)/kg dry matter (DM) or less is desirable. This work has examined the DCAD of 16 field-grown species found in pasture in southern Australia. The DCAD [cmol(+)/kg DM] at the flowering stage varied from 7 to 32 for grasses, 21 to 72 for legumes and 72 to 99 for dicot weeds. The average DCAD for legumes was 50 cmol(+)/kg DM, over 2-fold higher than the 20 cmol(+)/kg DM average for grasses. There was a substantial decline in DCAD of herbage as the season progressed. In a glasshouse experiment with five grass species in an acid soil, lime application increased yield and tended to lower the DCAD. Lime decreased uptake per unit root length of potassium and chlorine and increased uptake of calcium by phalaris and timothy. While DCAD is an important attribute of herbage for assessing its suitability for prepartum diets of dairy cows, the present data indicate that it would be prudent to also consider concentrations of calcium and other mineral nutrients in herbage, particularly when examining less familiar plant species or the effects of different cultural practices on the composition of herbage for such diets.
{"title":"Dietary cation–anion differences in some pasture species, changes during the season and effects of soil acidity and lime amendment","authors":"S. Pelletier, R. Simpson, R. Culvenor, G. Bélanger, G. Tremblay, G. Allard, J. Braschkat, P. Randall","doi":"10.1071/EA08121","DOIUrl":"https://doi.org/10.1071/EA08121","url":null,"abstract":"The difference between cation and anion concentrations is an important property when assessing feed for dry dairy cows in order to avoid hypocalcaemia following calving. Dietary cation–anion difference (DCAD) is used to assess suitability of feed and predict the risk of milk fever; a value of –5 cmol(+)/kg dry matter (DM) or less is desirable. This work has examined the DCAD of 16 field-grown species found in pasture in southern Australia. The DCAD [cmol(+)/kg DM] at the flowering stage varied from 7 to 32 for grasses, 21 to 72 for legumes and 72 to 99 for dicot weeds. The average DCAD for legumes was 50 cmol(+)/kg DM, over 2-fold higher than the 20 cmol(+)/kg DM average for grasses. There was a substantial decline in DCAD of herbage as the season progressed. In a glasshouse experiment with five grass species in an acid soil, lime application increased yield and tended to lower the DCAD. Lime decreased uptake per unit root length of potassium and chlorine and increased uptake of calcium by phalaris and timothy. While DCAD is an important attribute of herbage for assessing its suitability for prepartum diets of dairy cows, the present data indicate that it would be prudent to also consider concentrations of calcium and other mineral nutrients in herbage, particularly when examining less familiar plant species or the effects of different cultural practices on the composition of herbage for such diets.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1143-1153"},"PeriodicalIF":0.0,"publicationDate":"2008-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58805214","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}
There is an increasing trend towards integrated research, in which several individuals or institutions pool their expertise and make use of common resources, collaborating towards a common set of scientific goals. Integrated research enables a larger number of factors to be investigated, and the most influential or important ones identified, providing information on how the different factors interact or fit together. Good experimental design is, however, required to ensure the aims can be achieved and resources spent wisely. Issues involved in the experimental design of the Australian Beef Cattle Cooperative Research Centre for Meat Quality are discussed. Theoretical results and simulation studies were used to determine optimal numbers of progeny per sire for estimating genetic parameters. For heritabilities of 0.2 and 0.5, the optima are respectively 21 and 9 progeny with recorded measurements. The curves surrounding the optima are quite flat, so aiming for 10–15 progeny with measurements per trait should provide reasonable accuracy in many situations. Estimates of heritabilities, genetic correlations and phenotypic variances have lower sampling correlations than genetic variances and covariances, suggesting that when results are pooled over different breeds or trials, it is better to pool estimates of heritabilities and genetic correlations than (co)variances. Using sires in more than one year increases the robustness of estimated sire effects and increases the accuracy of genetic parameter estimates for hard-to-measure traits (e.g. feed efficiency) that are not recorded on all animals. Unless sires can be chosen as a true random sample of the population, arrangements of link sires (and other effects such as treatments) should be chosen to provide accurate estimates when all terms in the model are fitted as fixed.
{"title":"Designing complex research projects to estimate genetic parameters plus treatment and other effects – optimising the experimental design","authors":"D. L. Robinson","doi":"10.1071/EA07356","DOIUrl":"https://doi.org/10.1071/EA07356","url":null,"abstract":"There is an increasing trend towards integrated research, in which several individuals or institutions pool their expertise and make use of common resources, collaborating towards a common set of scientific goals. Integrated research enables a larger number of factors to be investigated, and the most influential or important ones identified, providing information on how the different factors interact or fit together. Good experimental design is, however, required to ensure the aims can be achieved and resources spent wisely. Issues involved in the experimental design of the Australian Beef Cattle Cooperative Research Centre for Meat Quality are discussed. Theoretical results and simulation studies were used to determine optimal numbers of progeny per sire for estimating genetic parameters. For heritabilities of 0.2 and 0.5, the optima are respectively 21 and 9 progeny with recorded measurements. The curves surrounding the optima are quite flat, so aiming for 10–15 progeny with measurements per trait should provide reasonable accuracy in many situations. Estimates of heritabilities, genetic correlations and phenotypic variances have lower sampling correlations than genetic variances and covariances, suggesting that when results are pooled over different breeds or trials, it is better to pool estimates of heritabilities and genetic correlations than (co)variances. Using sires in more than one year increases the robustness of estimated sire effects and increases the accuracy of genetic parameter estimates for hard-to-measure traits (e.g. feed efficiency) that are not recorded on all animals. Unless sires can be chosen as a true random sample of the population, arrangements of link sires (and other effects such as treatments) should be chosen to provide accurate estimates when all terms in the model are fitted as fixed.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1110-1117"},"PeriodicalIF":0.0,"publicationDate":"2008-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58797673","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}
G. Attwood, W. Kelly, E. Altermann, C. Moon, S. Leahy, A. Cookson
Sequencing the genomes of individual rumen microbes and determining the function of their encoded genes promises to transform our understanding of the microbiology of the rumen. The diversity and density of microbes in the rumen, and our inability to culture the majority of rumen microbes, limit current genome studies to only a small fraction of the microbes present in this environment. Nevertheless, genomes of fibre-degrading organisms are beginning to reveal a previously unexpected abundance of genes encoding glycosyl hydrolases and carbohydrate esterases, which could be used to enhance fibre digestion in the rumen. Additionally, genome sequencing of a rumen methanogen is identifying conserved genes within the methanogenic archaea that may serve as targets for their inhibition and therefore reduction of methane emissions from ruminants. The problem of rumen microbe culturability can be overcome by a new approach called metagenomics, in which microbial DNAs are extracted from rumen samples and sequenced independent of cultivation. In the future, sequencing individual genomes and metagenomic libraries is likely to capture much more of the microbial DNA in the rumen and, coupled with postgenomic studies on gene and protein expression, is likely to enhance our knowledge of the microbial component of ruminant digestion.
{"title":"Application of rumen microbial genome information to livestock systems in the postgenomic era","authors":"G. Attwood, W. Kelly, E. Altermann, C. Moon, S. Leahy, A. Cookson","doi":"10.1071/EA07408","DOIUrl":"https://doi.org/10.1071/EA07408","url":null,"abstract":"Sequencing the genomes of individual rumen microbes and determining the function of their encoded genes promises to transform our understanding of the microbiology of the rumen. The diversity and density of microbes in the rumen, and our inability to culture the majority of rumen microbes, limit current genome studies to only a small fraction of the microbes present in this environment. Nevertheless, genomes of fibre-degrading organisms are beginning to reveal a previously unexpected abundance of genes encoding glycosyl hydrolases and carbohydrate esterases, which could be used to enhance fibre digestion in the rumen. Additionally, genome sequencing of a rumen methanogen is identifying conserved genes within the methanogenic archaea that may serve as targets for their inhibition and therefore reduction of methane emissions from ruminants. The problem of rumen microbe culturability can be overcome by a new approach called metagenomics, in which microbial DNAs are extracted from rumen samples and sequenced independent of cultivation. In the future, sequencing individual genomes and metagenomic libraries is likely to capture much more of the microbial DNA in the rumen and, coupled with postgenomic studies on gene and protein expression, is likely to enhance our knowledge of the microbial component of ruminant digestion.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"467 1","pages":"695-700"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58798588","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}
This review will focus on the evidence for in utero effects on development of skeletal muscle in farm and laboratory animals, particularly sheep and pigs. We will describe genetic and environmental factors that have been shown to alter the numbers of muscle fibres formed and outline our working hypothesis for the mechanism involved and the critical window during pregnancy when these effects are seen. We will then discuss the long-term consequences in terms of body composition. Although this review concentrates on skeletal muscle development, the mechanism we suggest might be equally applicable to other tissues in the body (e.g. the brain, kidneys or sex organs) and, therefore, impact on their physiological functions.
{"title":"In utero effects on livestock muscle development and body composition","authors":"J. Brameld, Z. Daniel","doi":"10.1071/EA08017","DOIUrl":"https://doi.org/10.1071/EA08017","url":null,"abstract":"This review will focus on the evidence for in utero effects on development of skeletal muscle in farm and laboratory animals, particularly sheep and pigs. We will describe genetic and environmental factors that have been shown to alter the numbers of muscle fibres formed and outline our working hypothesis for the mechanism involved and the critical window during pregnancy when these effects are seen. We will then discuss the long-term consequences in terms of body composition. Although this review concentrates on skeletal muscle development, the mechanism we suggest might be equally applicable to other tissues in the body (e.g. the brain, kidneys or sex organs) and, therefore, impact on their physiological functions.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"33 1","pages":"921-929"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58800974","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}
Breakfast beef, stir-fry, pot-roast and oven-roast meats were prepared from the brisket, clod, inside round and knuckle of bulls on two pasture-based finishing diets (6 weeks of grain supplement before slaughter or no supplement). Diet affected the fatness of the raw meat but had no significant effect on the attributes assessed by the in-house consumer or trained panel. Stir fry from brisket, and pot roast and oven roast from brisket and clod, had higher (P knuckle > inside round > brisket; and that of product acceptability with appropriate processing was breakfast beef > oven roast > pot roast > stir fry. Female in-house consumer panellists assigned lower acceptability scores to the beef products than their male counterparts (P < 0.05). Because none of the muscles or products made from the muscles were totally rejected by the consumer panel (overall scores range from 4.2 to 7.0), there is potential to add value to these cuts through further processing.
{"title":"The effect of finishing diet and meat cuts on the attributes of four processed products from bull beef","authors":"M. Farouk, C. Podmore, C. Boom, G. Sheath","doi":"10.1071/EA07395","DOIUrl":"https://doi.org/10.1071/EA07395","url":null,"abstract":"Breakfast beef, stir-fry, pot-roast and oven-roast meats were prepared from the brisket, clod, inside round and knuckle of bulls on two pasture-based finishing diets (6 weeks of grain supplement before slaughter or no supplement). Diet affected the fatness of the raw meat but had no significant effect on the attributes assessed by the in-house consumer or trained panel. Stir fry from brisket, and pot roast and oven roast from brisket and clod, had higher (P knuckle > inside round > brisket; and that of product acceptability with appropriate processing was breakfast beef > oven roast > pot roast > stir fry. Female in-house consumer panellists assigned lower acceptability scores to the beef products than their male counterparts (P < 0.05). Because none of the muscles or products made from the muscles were totally rejected by the consumer panel (overall scores range from 4.2 to 7.0), there is potential to add value to these cuts through further processing.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"853-859"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58798145","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}
J. Lea, D. Niemeyer, M. Reed, A. Fisher, D. Ferguson
This series of experiments was undertaken to develop a low animal impact, inexpensive and simple method of continuous logging of body temperature in free-ranging adult cattle for periods up to 7 days. Two different types of logger (iButton and Vemco minilogger) and three different methods of attachment (surgical implant, anal girth strap and anal tail attachment) for the iButton were investigated. The technique based on the iButton temperature logger, secured to the tail head was the most effective. This technique required minimal animal handling and provided reliable and accurate measurement of temperature in freely behaving cattle.
{"title":"Development and validation of a simple technique for logging body temperature in free-ranging cattle","authors":"J. Lea, D. Niemeyer, M. Reed, A. Fisher, D. Ferguson","doi":"10.1071/EA07422","DOIUrl":"https://doi.org/10.1071/EA07422","url":null,"abstract":"This series of experiments was undertaken to develop a low animal impact, inexpensive and simple method of continuous logging of body temperature in free-ranging adult cattle for periods up to 7 days. Two different types of logger (iButton and Vemco minilogger) and three different methods of attachment (surgical implant, anal girth strap and anal tail attachment) for the iButton were investigated. The technique based on the iButton temperature logger, secured to the tail head was the most effective. This technique required minimal animal handling and provided reliable and accurate measurement of temperature in freely behaving cattle.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"741-745"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07422","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58800011","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}
E. Ponnampalam, K. Butler, D. Hopkins, M. Kerr, F. Dunshea, R. Warner
Leanmeatand fat content of Australiansheep genotypes were comparedat20-,30- and 40-kg carcass weights. Sheep comprised Poll Dorsetgrowth ·Border Leicester Merino (PDg ·BLM), Poll Dorsetgrowth ·Merino (PDg ·M), Poll Dorsetmuscling ·Merino (PDm ·M), Border Leicester ·Merino (BL ·M) and Merino ·Merino (M ·M) genotypes. Lambs wereraisedasamixedflockundergrazingandslaughteredat4,8,14and22monthsofagewitheachslaughtertimeinvolving ~150mixed sex animals. At 24h after slaughter, chilled carcasses were halved along the backbone and the right sides were usedfordeterminationoflean,fatandashpercentagesusingdualenergyX-rayabsorptiometry.Withinaparticularagegroup andgenotype,animalsgrowingatfasterratesandreachingheaviercarcassweightshadlowercarcassleanmeatcontentthan slowergrowinganimals.Merinocarcassesweighing20and30kghadsimilarlevelsofleanmeattoPD ·Mgenotypes,which wasgreaterthanthatfromtheBL ·Mgenotype.Second-crossPD ·BLMcarcassesweighing20kgat4monthsand30kgat 8monthshadsimilarcarcassfatandleanpercentagesto20-kgMerinocarcassesat8monthsandfirst-crossPD ·Mcarcasses weighing30kgat14 months, respectively. At40-kgcarcass weight, 22-month-oldMerinoshad similarlevelsofleannessto carcasses from 22-month-old PD ·M animals and carcasses from 14-month-old second-cross PD ·BLM animals. Carcass leanmeatcontentdecreasedwithincreasingcarcassweightandfirst-crossBL ·Manimalshadthelowestcarcassleanacross allweightcategories.Therewasamajoraccelerationincarcassfatnessbetween14and22monthsassociatedwithareduction inmuscle deposition.Results indicatethatage ofthe animalshouldbe taken intoaccount whencarcass leanand fat contents are compared at a particular carcass weight. Merinos will achieve weight/composition specifications at least equally well to crossbreds but will take longer with a likely increase in production costs.
{"title":"Genotype and age effects on sheep meat production. 5. Lean meat and fat content in the carcasses of Australian sheep genotypes at 20-, 30- and 40-kg carcass weights","authors":"E. Ponnampalam, K. Butler, D. Hopkins, M. Kerr, F. Dunshea, R. Warner","doi":"10.1071/EA08054","DOIUrl":"https://doi.org/10.1071/EA08054","url":null,"abstract":"Leanmeatand fat content of Australiansheep genotypes were comparedat20-,30- and 40-kg carcass weights. Sheep comprised Poll Dorsetgrowth ·Border Leicester Merino (PDg ·BLM), Poll Dorsetgrowth ·Merino (PDg ·M), Poll Dorsetmuscling ·Merino (PDm ·M), Border Leicester ·Merino (BL ·M) and Merino ·Merino (M ·M) genotypes. Lambs wereraisedasamixedflockundergrazingandslaughteredat4,8,14and22monthsofagewitheachslaughtertimeinvolving ~150mixed sex animals. At 24h after slaughter, chilled carcasses were halved along the backbone and the right sides were usedfordeterminationoflean,fatandashpercentagesusingdualenergyX-rayabsorptiometry.Withinaparticularagegroup andgenotype,animalsgrowingatfasterratesandreachingheaviercarcassweightshadlowercarcassleanmeatcontentthan slowergrowinganimals.Merinocarcassesweighing20and30kghadsimilarlevelsofleanmeattoPD ·Mgenotypes,which wasgreaterthanthatfromtheBL ·Mgenotype.Second-crossPD ·BLMcarcassesweighing20kgat4monthsand30kgat 8monthshadsimilarcarcassfatandleanpercentagesto20-kgMerinocarcassesat8monthsandfirst-crossPD ·Mcarcasses weighing30kgat14 months, respectively. At40-kgcarcass weight, 22-month-oldMerinoshad similarlevelsofleannessto carcasses from 22-month-old PD ·M animals and carcasses from 14-month-old second-cross PD ·BLM animals. Carcass leanmeatcontentdecreasedwithincreasingcarcassweightandfirst-crossBL ·Manimalshadthelowestcarcassleanacross allweightcategories.Therewasamajoraccelerationincarcassfatnessbetween14and22monthsassociatedwithareduction inmuscle deposition.Results indicatethatage ofthe animalshouldbe taken intoaccount whencarcass leanand fat contents are compared at a particular carcass weight. Merinos will achieve weight/composition specifications at least equally well to crossbreds but will take longer with a likely increase in production costs.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"893-897"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08054","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58803061","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}
This paper reviews opportunities to improve the diet quality, intake and performance of animals through manipulation of the partial preference commonly shown by grazing animals for different pasture components. Using evidence from the well-worked example of grass–legume pastures, potential opportunities to manipulate preference are highlighted, including: (i) altering plant characteristics to change the relative preference of alternative species or cultivars; (ii) utilising variation in preference among and within animal species; and (iii) working with, rather than against, known preference patterns, by offering forages as spatially separated monocultures within the same paddock or at different times of the day. In all cases, it is argued that is important to consider the full complexities of pasture–animal interactions, in particular, how current diet choices feed back to determine choices available subsequently in the pasture. To develop feeding systems where desirable pasture traits for animal performance are sustained at a high abundance in the diet, plant and animal breeding selection practises and grazing management systems should take greater account of the existence of partial preferences.
{"title":"Manipulating dietary preference to improve animal performance","authors":"G. Edwards, A. Parsons, R. Bryant","doi":"10.1071/EA08006","DOIUrl":"https://doi.org/10.1071/EA08006","url":null,"abstract":"This paper reviews opportunities to improve the diet quality, intake and performance of animals through manipulation of the partial preference commonly shown by grazing animals for different pasture components. Using evidence from the well-worked example of grass–legume pastures, potential opportunities to manipulate preference are highlighted, including: (i) altering plant characteristics to change the relative preference of alternative species or cultivars; (ii) utilising variation in preference among and within animal species; and (iii) working with, rather than against, known preference patterns, by offering forages as spatially separated monocultures within the same paddock or at different times of the day. In all cases, it is argued that is important to consider the full complexities of pasture–animal interactions, in particular, how current diet choices feed back to determine choices available subsequently in the pasture. To develop feeding systems where desirable pasture traits for animal performance are sustained at a high abundance in the diet, plant and animal breeding selection practises and grazing management systems should take greater account of the existence of partial preferences.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"773-779"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58800485","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}
I. Cassar-Malek, B. Picard, C. Bernard, J. Hocquette
In the context of sustainable agriculture and animal husbandry, understanding animal physiology remains a major challenge in the breeding and production of livestock, especially to develop animal farming systems that respond to the new and diversified consumer demand. Physiological processes depend on the expression of many genes acting in concert. Considerable effort has been expended in recent years on examining the mechanisms controlling gene expression and their regulation by biological and external factors (e.g. genetic determinants, nutritional factors, and animal management). Two main strategies have been developed to identify important genes. The first one has focussed on the expression of candidate genes for key physiological pathways at the level of both the transcripts and proteins. An original strategy has emerged with the advent of genomics that addresses the same issues through the examination of the molecular signatures of all genes and proteins using high-throughput techniques (e.g. transcriptomics and proteomics). In this review, the application of the gene expression studies in livestock production systems is discussed. Some practical examples of genomics applied to livestock production systems (e.g. to optimise animal nutrition, meat quality or animal management) are presented, and their outcomes are considered. In the future, integration of the knowledge gained from these studies will finally result in optimising livestock production systems through detection of desirable animals and their integration into accurate breeding programs or innovative management systems.
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