Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
1.
J Dairy Sci ; 95(4): 2027-36, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22459848

RESUMO

Several technologies have been tested to reduce enteric methanogenesis, but very few have been successfully used in practical conditions for livestock. Furthermore, the consequences of reduced rumen methane production on animal performance and milk quality are poorly understood. The aim of this work was to investigate the effect of feeding bromochloromethane (BCM), a halogenated aliphatic hydrocarbon with potential antimethanogenic activity, to dairy goats on rumen methane production, fermentation pattern, the abundance of major microbial groups, and on animal performance and milk composition. Eighteen goats were allocated to 2 experimental groups of 9 animals each: treated (BCM+) or not (BCM-) with 0.30 g of BCM/100 kg of body weight per day. The BCM was administered per os in 2 equal doses per day from parturition to 2 wk postweaning (10 wk). After weaning, methane emissions were recorded over 2 consecutive days (d 57 and 58 on treatment) in polycarbonate chambers. On d 59, individual rumen fluid samples were collected for volatile fatty acid (VFA) analysis and quantification of bacterial, protozoal, and archaeal numbers by real-time PCR. On d 69 and 70, daily milk production was recorded and samples were collected for determination of fat, protein, lactose, casein, and total solids concentration by infrared spectrophotometry, and fatty acid composition by gas chromatography. Treatment with BCM reduced methane production by 33% (21.6 vs. 14.4 L/kg of DMI) compared with nontreated animals, although it did not affect the abundance of rumen bacteria, protozoa, and total methanogenic archaea. The observed improvement in the efficiency of digestive processes was accompanied by a 36% increase in milk yield, probably due to the more propionic type of rumen fermentation and an increase in VFA production. The increase in milk yield was not accompanied by any changes in the concentrations or yields of fat, protein, or lactose. Despite the substantial decrease in methane production, only minor changes in milk fatty acid profile were observed, suggesting that ruminal biohydrogenation pathways were not affected. Compounds that influence terminal biochemical pathways for methane production deserve further development for future application in the dairy goat sector.


Assuntos
Ácidos Graxos/análise , Cabras/metabolismo , Hidrocarbonetos Halogenados/administração & dosagem , Metano/biossíntese , Leite/química , Rúmen/metabolismo , Animais , Dieta/veterinária , Ácidos Graxos Voláteis/análise , Feminino , Fermentação/efeitos dos fármacos , Lactação/efeitos dos fármacos , Rúmen/efeitos dos fármacos , Rúmen/microbiologia
2.
J Environ Qual ; 40(1): 22-7, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21488489

RESUMO

The ability to accurately measure greenhouse gas (GHG) emissions is essential to gauge our ability to reduce these emissions. Enteric methane from ruminants is an important but often difficult source to quantify since it depends on the amount and type of feed intake. Unfortunately, many of the available measurement techniques for estimating enteric methane emissions can impose a change in feed intake. Our study evaluates a nonintrusive technique that uses a novel approach (point-source dispersion with multiple open-path concentrations) to calculate enteric methane emissions from grazing cattle, reported as the major source of GHG in many countries, particularly Australia. A scanner with a mounted open-path laser was used to measure methane concentration across five paths above a paddock containing 18 grazing cattle over 16 d. These data were used along with wind statistics in a dispersion model (WindTrax) to estimate an average herd methane emission rate over 10-mm intervals. Enteric methane emissions from the herd grazing a combination of Rhodes grass (Chlotis gayana Kunth) and Leucaena [Leucaena leucocephala (Lam.)] averaged (+/- SD) 141 (+/- 147) g animal(-1) d(-1). In a release-recovery experiment, the technique accounted for 77% of the released methane at a single point. Our study shows the technique generates more reliable methane emissions during daytime (unstable stratification).


Assuntos
Poluentes Atmosféricos/química , Bovinos/metabolismo , Monitoramento Ambiental/métodos , Metano/química , Metano/metabolismo , Criação de Animais Domésticos , Animais , Ritmo Circadiano , Aquecimento Global , Abrigo para Animais , Masculino , Fatores de Tempo , Vento
3.
Aust Vet J ; 83(8): 496-8, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16119423

RESUMO

OBJECTIVE: To measure haematological values of clinical significance for rusa deer and provide reference data for farmed animals. DESIGN: Blood samples were collected regularly from eight male rusa deer from 14 days to 27 months old. PROCEDURE: Blood samples, collected by venipuncture, were analysed within 6 hours of collection for red cell count, haemoglobin, packed cell volume, plasma glucose, white cell count and differentials. RESULTS: Haemoglobin concentrations appeared to increase with age and ranged from 6.0 to 20.9 g/dL. Packed cell volume and plasma glucose concentration did not appear to vary with age. White cell counts ranged from 6.3 to 7.0 x 10(9)/L and differential counts indicated neutrophils > lymphocytes > monocytes > eosinophils > basophils. In general, the values for packed cell volume, red cell count, mean cell volumes and mean cell haemoglobin concentrations were within ranges previously reported for captive or sedated rusa deer. CONCLUSIONS: Physical restraint and resultant stress was sufficient to generate some of the effects previously reported for physically immobilised or agitated deer. The values reported here do not differ greatly from those previously reported for rusa deer and can be used as reference values for clinically healthy young farmed male rusa deer.


Assuntos
Cervos/sangue , Testes Hematológicos/veterinária , Envelhecimento/fisiologia , Animais , Contagem de Células Sanguíneas/veterinária , Glicemia/análise , Hematócrito/veterinária , Testes Hematológicos/métodos , Testes Hematológicos/normas , Hemoglobinas/análise , Masculino , Valores de Referência
4.
Animal ; 9(12): 2029-38, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26290115

RESUMO

Methane (CH4) emissions associated with beef production systems in northern Australia are yet to be quantified. Methodologies are available to measure emissions, but application in extensive grazing environments is challenging. A micrometeorological methodology for estimating herd-scale emissions using an indirect open-path spectroscopic technique and an atmospheric dispersion model is described. The methodology was deployed on five cattle properties across Queensland and Northern Territory, with measurements conducted during two occasions at one site. On each deployment, data were collected every 10 min for up to 7 h a day over 4 to 16 days. To increase the atmospheric concentration of CH4 to measurable levels, cattle were confined to a known area around water points from ~0800 to 1600 h, during which time measurements of wind statistics and line-averaged CH4 concentration were taken. Filtering to remove erroneous data accounted for 35% of total observations. For five of the six deployments CH4 emissions were within the expected range of 0.4 to 0.6 g/kg BW. At one site, emissions were ~2 times expected values. There was small but consistent variation with time of day, although for some deployments measurements taken early in the day tended to be higher than at the other times. There was a weak linear relationship (R 2=0.47) between animal BW and CH4 emission per kg BW. Where it was possible to compare emissions in the early and late dry season at one site, it was speculated that higher emissions at the late dry season may have been attributed to poorer diet quality. It is concluded that the micrometeorological methodology using open-path lasers can be successfully deployed in extensive grazing conditions to directly measure CH4 emissions from cattle at a herd scale.


Assuntos
Bovinos/fisiologia , Metano/análise , Análise Espectral/métodos , Animais , Atmosfera , Austrália , Monitoramento Ambiental , Feminino , Pradaria , Lasers , Masculino , Metano/metabolismo , Estações do Ano , Vento
5.
Aust Vet J ; 75(10): 722-3, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9406629

RESUMO

On the basis of clinical signs and histological findings eight 9-month-old male rusa deer (Cervus timorensis) were diagnosed with sheep associated-malignant catarrhal fever. Following a variable course involving rectal temperatures around 40.5 degrees C, depression, inappetence, diarrhoea, corneal opacity and hypopyon all animals died or were euthanased over a 5-week period. Severe multifocal vasculitis, mainly periglomerular and in the arcuate vessels were consistent histological findings which in the past have been adequate to confirm clinical diagnosis of sheep associated-malignant catarrhal fever. A nested polymerase chain reaction test has been used to detect a sheep associated-malignant catarrhal fever PRC product, 238 base-pairs in size, in DNA extracted from lymphocyte preparations. The result supported the diagnosis of sheep associated-malignant catarrhal fever in these deer.


Assuntos
Cervos , Surtos de Doenças/veterinária , Febre Catarral Maligna/epidemiologia , Fatores Etários , Animais , DNA Viral/análise , DNA Viral/genética , Herpesviridae/genética , Linfócitos/química , Masculino , Febre Catarral Maligna/diagnóstico , Reação em Cadeia da Polimerase/métodos , Reação em Cadeia da Polimerase/veterinária , Queensland/epidemiologia
6.
Animal ; 7 Suppl 2: 363-72, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23739477

RESUMO

The growing global demand for food of animal origin will be the incentive for countries such as Australia and Brazil to increase their beef production and international exports. This increased supply of beef is expected to occur primarily through on-farm productivity increases. The strategies for reducing resultant greenhouse gas (GHG) emissions should be evaluated in the context of the production system and should encompass a broader analysis, which would include the emissions of methane (CH4) and nitrous oxide (N2O) and carbon sequestration. This paper provides an insight into CH4 measurement techniques applicable to grazing environments and proposed mitigation strategies, with relevance to the production systems that are predominant in grazing systems of Australia and Brazil. Research and technology investment in both Australia and Brazil is aimed at developing measurement techniques and increasing the efficiency of cattle production by improving herd genetics, utilization of the seasonal feed-base and reducing the proportion of metabolizable energy lost as CH4. Concerted efforts in these areas can be expected to reduce the number of unproductive animals, reduce age at slaughter and inevitably reduce emission intensity (EI) from beef production systems. Improving efficiency of livestock production systems in tropical grazing systems for Australia and Brazil will be based on cultivated and existing native pastures and the use of additives and by-products from other agricultural sectors. This approach spares grain-based feed reserves typically used for human consumption, but potentially incurs a heavier EI than current intensive feeding systems. The determination of GHG emissions and the value of mitigation outcomes for entire beef production systems in the extensive grazing systems is complex and require a multidisciplinary approach. It is fortunate that governments in both Australia and Brazil are supporting ongoing research activities. Nevertheless, to achieve an outcome that feeds a growing population while reducing emissions on a global scale continues to be a monumental challenge for ruminant nutritionists.


Assuntos
Poluentes Atmosféricos/metabolismo , Monitoramento Ambiental/métodos , Recuperação e Remediação Ambiental/métodos , Metano/metabolismo , Criação de Animais Domésticos , Austrália , Brasil , Meio Ambiente
7.
J Anim Sci ; 87(10): 3114-23, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19542515

RESUMO

This study determined the extent to which bovine longissimus lumborum muscle (LLM) myofibers are influenced by nutrition for 120 d from weaning and the time-course of recovery after severe postweaning nutritional restriction. After weaning, 3 groups of Belmont Red cattle, a tropically adapted breed, were fed to achieve rapid growth (RG, > or =0.6 kg of BW gain/d; n = 16), slow growth (SG, 0.2 kg of BW gain/d; n = 17), or BW loss (WL, 10% loss of weaning weight; n = 17) over 120 d. They were then grazed as 1 group at pasture with forage supplementation for 600 d until slaughter at approximately 500 kg of BW. Samples of LLM were taken from 8 to 12 animals per treatment 6 d before (baseline) and 115, 204, 324, and 476 d after commencement of the study and from all cattle at slaughter (d 721). Myofiber characteristics were determined by immunocytochemical staining of myosin heavy chains. Cross-sectional areas (CSA) of the major myofiber types 1, 2A, and 2X in WL were reduced at d 115 compared with baseline and with the growth groups (all P < 0.001); however, there was little difference in the percentage of the different myofiber types (all P > 0.10). Differences in CSA of the major myofiber types between WL and the growth groups at 115 d were smallest for type 1 (slow oxidative) and greatest for type 2X (fast glycolytic). Consequently, the relative area (percentage of total myofiber area) of type 1 myofibers in WL was significantly greater at 115 d than in the growth groups (P < 0.001). During recovery from postweaning nutritional restriction, significant differences in major myofiber type percentages were not evident (all P > 0.10), and by 721 d CSA of myofiber types differed little between the treatment groups, although SG had greater CSA of type 1 (P < 0.05) and type 2A (P < 0.01) myofibers than WL and RG. At 721 d, the relative area of type 2A myofibers was less in WL compared with SG (P < 0.01) and RG (P < 0.05) and of type 2X myofibers greater (P < 0.05) in WL compared with SG. It is concluded that in the LLM of cattle undergoing severe nutritional restriction immediately postweaning, the size of the more glycolytic fiber types is more adversely affected than the more oxidative types, resulting in an increased relative area of type 1, slow oxidative myofibers. However, given adequate time and nutriment at pasture, LLM myofiber characteristics of cattle recovered to near normal after severe, chronic nutritional restriction immediately postweaning, consistent with earlier findings for beef quality.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal/fisiologia , Bovinos/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Animais , Austrália , Biópsia/veterinária , Peso Corporal/fisiologia , Imuno-Histoquímica/veterinária , Carne , Distribuição Aleatória , Clima Tropical
8.
J Appl Microbiol ; 99(4): 885-94, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16162240

RESUMO

AIM: To determine the effect of different carbohydrate-based finishing diets on fermentation characteristics and the shedding of Escherichia coli and enterohaemorrhagic E. coli (EHEC) virulence genes in cattle faeces. METHODS AND RESULTS: The size of faecal E. coli populations and fermentation characteristics were ascertained in three experiments where cattle were maintained on a range of finishing diets including high grain, roughage, and roughage + molasses (50%) diets. Increased E. coli numbers, decreased pH and enhanced butyrate and lactate fermentation pathways were associated with grain diets, whereas roughage and roughage + molasses diets resulted in decreased concentrations of ehxA, eaeA and stx(1) genes, this trend remaining at lairage. In one experiment, faecal E. coli numbers were significantly lower in animals fed roughage and roughage + molasses, than animals fed grain (4.5, 5.2 and 6.3 mean log10 g(-1) digesta respectively). In a second experiment, faecal E. coli numbers were 2 log lower in the roughage and roughage + molasses diets compared with grain-fed animals prior to lairage (5.6, 5.5 and 7.9 mean log10 g(-1) digesta respectively) this difference increasing to 2.5 log at lairage. CONCLUSIONS: The type of dietary carbohydrate has a significant effect on E. coli numbers and concentration of EHEC virulence genes in faeces of cattle. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides a better understanding of the impact finishing diet and commercial lairage management practices may have on the shedding of E. coli and EHEC virulence factors, thus reducing the risk of carcass contamination by EHEC.


Assuntos
Ração Animal/microbiologia , Escherichia coli/crescimento & desenvolvimento , Fezes/microbiologia , Genes Bacterianos/genética , Animais , Butiratos/metabolismo , Bovinos , Contagem de Colônia Microbiana/métodos , Carboidratos da Dieta/administração & dosagem , Fibras na Dieta , Grão Comestível , Escherichia coli/genética , Escherichia coli/patogenicidade , Fermentação , Concentração de Íons de Hidrogênio , Lactatos/metabolismo , Melaço , Virulência/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA