RESUMO
Angus cattle from 2 beef cattle projects in which daily methane production (MPR) was measured were used in this study to examine the nature of the relationships among BW, DMI, and methane traits of beef cattle fed ad libitum on a roughage diet or a grain-based feedlot diet. In both projects methane was measured using the GreenFeed Emission Monitoring system, which provides multiple short-term breath measures of methane production. The data used for this study were from 119 Angus heifers over 15 d on a roughage diet and 326 Angus steers over 70 d on a feedlot diet. Mean (±SD) age, BW, and DMI were 372 ± 28 d, 355 ± 37 kg, and 8.1 ± 1.3 kg/d for the heifers and 554 ± 86 d, 577 ± 69 kg, and 13.3 ± 2.0 kg/d for the steers, respectively. The corresponding mean MPR was 212 g/d for heifers and 203 g/d for steers. Additional traits studied included methane yield (MY; MPR/DMI), methane intensity (MPR/BW), and 3 forms of residual methane production (RMP), which is a measure of actual minus predicted MPR. For RMP, RMP, and RMP predicted MPR were obtained by regression of MPR on BW, on DMI, and on both DMI and BW, respectively. The 2 data sets were analyzed separately using the same statistical procedures. For both feed types the relationships between MPR and DMI and between MPR and BW were both positive and linear. The correlation between MPR and DMI was similar to that between MPR and BW, although the correlations were stronger for the roughage diet ( = 0.75 for MPR vs. DMI; = 0.74 for MPR vs. BW) than the grain-based diet ( = 0.62 for MPR vs. DMI; = 0.66 for MPR vs. BW). The correlation between MY and DMI was negative and moderate for the roughage ( = -0.68) and grain-based ( = -0.59) diets, a finding that is different from the nonsignificant correlations reported in studies of cattle on a restricted roughage diet. The 3 RMP traits were strongly correlated ( values from 0.76 to 0.99) with each other for both the roughage and the grain-based diets, which indicates that using RMP to lower MPR could provide a result similar to using RMP in cattle. As feed intake (DMI) is more difficult to measure than BW, this result implies that under ad libitum feeding situations in which DMI cannot be measured, RMP can be used to identify higher- or lower-RMP animals with similar levels of effectiveness as RMP.
Assuntos
Bovinos/fisiologia , Fibras na Dieta/análise , Comportamento Alimentar , Metano/metabolismo , Animais , Peso Corporal , Dieta/veterinária , Ingestão de Alimentos , Feminino , Modelos Lineares , Masculino , Dinâmica não Linear , FenótipoRESUMO
Respiration chambers are considered the reference method for quantifying the daily CH production rate (MPR) and CO production rate (CPR) of cattle; however, they are expensive, labor intensive, cannot be used in the production environment, and can be used to assess only a limited number of animals. Alternative methods are now available, including those that provide multiple short-term measures of CH and CO, such as the GreenFeed Emission Monitoring (GEM) system. This study was conducted to provide information for optimizing test procedures for estimating MPR and CPR of cattle from multiple short-term CH and CO records. Data on 495 Angus steers on a 70-d ad libitum feedlot diet with 46,657 CH and CO records and on 121 Angus heifers on a 15-d ad libitum roughage diet with 7,927 CH and CO records were used. Mean (SD) age and BW were 554 d (SD 92) and 506 kg (SD 73), respectively, for the steers and 372 d (SD 28) and 348 kg (SD 37), respectively, for the heifers. The 2 data sets were analyzed separately but using the same procedures to examine the reduction in variance as more records are added and to evaluate the level of precision with 2 vs. 3 min as the minimum GEM visit duration for a valid record. The moving averages procedure as well as the repeated measures procedure were used to calculate variances for both CH and CO, starting with 5 records and progressively increasing to a maximum of 80 records. For both CH and CO and in both data sets, there was a sharp reduction in the variances obtained by both procedures as more records were added. However, there was no substantial reduction in the variance after 30 records had been added. Inclusion of records with a minimum of 2-min GEM visit duration resulted in reduction in precision relative to a minimum of 3 min, as indicated by significantly ( < 0.05) more heterogeneous variances for all cases except CH4 in steers. In addition, more records were required to achieve the same level of precision relative to data with minimum GEM visit durations of 3 min. For example, in the steers, 72% reduction in initial variance was achieved with 30 records for both CH and CO when minimum GEM visit duration was 3 min, relative to 45 records when data with a minimum visit duration of 2 min were included. It is concluded from this study that when using records of multiple short-term breath measures of CH or CO for the computation of an animal's MPR or CPR, a minimum of 30 records, each record obtained from a minimum GEM visit duration of 3 min, are required.
Assuntos
Testes Respiratórios/métodos , Dióxido de Carbono/metabolismo , Bovinos/fisiologia , Metano/metabolismo , Poluentes Atmosféricos , Animais , MasculinoRESUMO
The objective of the study was to evaluate associations among animal performance and methane emission traits under feedlot conditions and in respiration chambers in Angus cattle bred to vary in residual feed intake (RFI), which is a measure of feed efficiency. Fifty-nine cattle were tested for feedlot RFI, of which 41 had methane production recorded on an ad libitum grain-based ration in the feedlot, 59 on a restricted grain-based ration in respiration chambers, and 57 on a restricted roughage ration in respiration chambers. The cattle became older and heavier as they went through the different phases of the experiment, but their feed intake (expressed as DMI) and daily emission of enteric methane (methane production rate; MPR) did not increase proportionally, as feed offered was restricted in the respiration chamber tests. Methane emissions by individual animals relative to their DMI were calculated as methane yield (MY; MPR/DMI) and as 2 measures of residual methane production (RMP and RMP), which were calculated as the difference between measured MPR and that predicted from feed intake by 2 different equations. Within each test regime, MPR was positively correlated ( = 0.28 to 0.61) with DMI. Phenotypic correlations for MY, RMP, and RMP between the feedlot test and the restricted grain test ( = 0.40 to 0.43) and between the restricted grain test and the restricted roughage test were moderate ( = 0.36 to 0.41) and moderate to strong between the feedlot test and the restricted roughage test ( = 0.54 to 0.58). These results indicate that the rankings of animals for methane production relative to feed consumed are relatively stable over the 3 test phases. Feedlot feed conversion ratio and RFI were not correlated with MPR in the feedlot test and grain-based chamber test but were negatively correlated with MPR in the chamber roughage test ( = -0.31 and -0.37). Both were negatively correlated with MY and RMP in the feedlot test ( = -0.42 to -0.54) and subsequent chamber roughage test ( = -0.27 to -0.49). Midparent estimated breeding values for RFI tended to be negatively correlated with MY and RMP in the feedlot test ( = -0.27 and -0.27) and were negatively correlated with MY, RMP, and RMP in the chamber roughage test ( = -0.33 to -0.36). These results showed that in young growing cattle, lower RFI was associated with higher MY, RMP, and RMP but had no significant association with MPR.
Assuntos
Bovinos/fisiologia , Metano/metabolismo , Ração Animal/análise , Animais , Cruzamento , Calorimetria Indireta/veterinária , Fibras na Dieta , Ingestão de Alimentos , Comportamento Alimentar , Masculino , FenótipoRESUMO
Ruminants contribute 80% of the global livestock greenhouse gas (GHG) emissions mainly through the production of methane, a byproduct of enteric microbial fermentation primarily in the rumen. Hence, reducing enteric methane production is essential in any GHG emissions reduction strategy in livestock. Data on 1,046 young bulls and heifers from 2 performance-recording research herds of Angus cattle were analyzed to provide genetic and phenotypic variance and covariance estimates for methane emissions and production traits and to examine the interrelationships among these traits. The cattle were fed a roughage diet at 1.2 times their estimated maintenance energy requirements and measured for methane production rate (MPR) in open circuit respiration chambers for 48 h. Traits studied included DMI during the methane measurement period, MPR, and methane yield (MY; MPR/DMI), with means of 6.1 kg/d (SD 1.3), 132 g/d (SD 25), and 22.0 g/kg (SD 2.3) DMI, respectively. Four forms of residual methane production (RMP), which is a measure of actual minus predicted MPR, were evaluated. For the first 3 forms, predicted MPR was calculated using published equations. For the fourth (RMP), predicted MPR was obtained by regression of MPR on DMI. Growth and body composition traits evaluated were birth weight (BWT), weaning weight (WWT), yearling weight (YWT), final weight (FWT), and ultrasound measures of eye muscle area, rump fat depth, rib fat depth, and intramuscular fat. Heritability estimates were moderate for MPR (0.27 [SE 0.07]), MY (0.22 [SE 0.06]), and the RMP traits (0.19 [SE 0.06] for each), indicating that genetic improvement to reduce methane emissions is possible. The RMP traits and MY were strongly genetically correlated with each other (0.99 ± 0.01). The genetic correlation of MPR with MY as well as with the RMP traits was moderate (0.32 to 0.63). The genetic correlation between MPR and the growth traits (except BWT) was strong (0.79 to 0.86). These results indicate that selection for lower MPR may have undesired effect on animal productivity. On the other hand, MY and the RMPR were either not genetically correlated or weakly correlated with BWT, YWT, and FWT (-0.06 to 0.23) and body composition traits (-0.18 to 0.18). Therefore, selection for lower MY or RMPR would lead to lower MPR without impacting animal productivity. Where the use of a ratio trait (e.g., MY) is not desirable, selection on any of the forms of RMP would be an alternative.
Assuntos
Bovinos/genética , Dieta/veterinária , Metano/metabolismo , Rúmen/fisiologia , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Peso ao Nascer , Composição Corporal/fisiologia , Bovinos/metabolismo , Comportamento Alimentar , Feminino , Fermentação , Masculino , Fenótipo , DesmameRESUMO
Enteric methane emissions from beef cattle are a significant component of total greenhouse gas emissions from agriculture. The variation between beef cattle in methane emissions is partly genetic, whether measured as methane production, methane yield (methane production/DMI), or residual methane production (observed methane production - expected methane production), with heritabilities ranging from 0.19 to 0.29. This suggests methane emissions could be reduced by selection. Given the high cost of measuring methane production from individual beef cattle, genomic selection is the most feasible approach to achieve this reduction in emissions. We derived genomic EBV (GEBV) for methane traits from a reference set of 747 Angus animals phenotyped for methane traits and genotyped for 630,000 SNP. The accuracy of GEBV was tested in a validation set of 273 Angus animals phenotyped for the same traits. Accuracies of GEBV ranged from 0.29 ± 0.06 for methane yield and 0.35 ± 0.06 for residual methane production. Selection on GEBV using the genomic prediction equations derived here could reduce emissions for Angus cattle by roughly 5% over 10 yr.
Assuntos
Cruzamento , Bovinos/genética , Bovinos/metabolismo , Genoma , Metano/biossíntese , Animais , Genômica , GenótipoRESUMO
Ruminants contribute up to 80% of greenhouse gas (GHG) emissions from livestock, and enteric methane production by ruminants is the main source of these GHG emissions. Hence, reducing enteric methane production is essential in any GHG emissions reduction strategy in livestock. Data from 2 performance-recording research herds of Angus cattle were used to evaluate a number of methane measures that target methane production (MPR) independent of feed intake and to examine their phenotypic relationships with growth and body composition. The data comprised 777 young bulls and heifers that were fed a roughage diet (ME of 9 MJ/kg DM) at 1.2 times their maintenance energy requirements and measured for MP in open circuit respiration chambers for 48 h. Methane traits evaluated included DMI during the methane measurement period, MPR, and methane yield (MY; MPR/DMI), with means (± SD) of 6.2 ± 1.4 kg/d, 187 ± 38 L/d, and 30.4 ± 3.5 L/kg, respectively. Four forms of residual MPR (RMP), which is a measure of actual minus predicted MPR, were evaluated. For the first 3 forms, predicted MPR was calculated using published equations. For the fourth (RMPR), predicted MPR was obtained by regression of MPR on DMI. Growth traits evaluated were BW at birth, weaning (200 d of age), yearling age (400 d of age), and 600 d of age, with means (± SD) of 34 ± 4.6, 238 ± 37, 357 ± 45, and 471 ± 53 kg, respectively. Body composition traits included ultrasound measures (600 d of age) of rib fat, rump fat, and eye muscle area, with means (± SD) of 3.8 ± 2.6 mm, 5.4 ± 3.8 mm, and 61 ± 7.7 cm(2), respectively. Methane production was positively correlated (r ± SE) with DMI (0.65 ± 0.02), MY (0.72 ± 0.02), the RMP traits (r from 0.65 to 0.79), the growth traits (r from 0.19 to 0.57), and the body composition traits (r from 0.13 to 0.29). Methane yield was, however, not correlated (r ± SE) with DMI (-0.02 ± 0.04) as well as the growth (r from -0.03 to 0.11) and body composition (r from 0.01 to 0.06) traits. All the RMP traits were strongly correlated to MY (r from 0.82 to 0.95). These results indicate that reducing MPR per se can have a negative impact on growth and body composition of cattle. Reducing MY, however, will likely have the effect of reducing MPR without impacting productivity. Where a ratio trait is undesirable, as in animal breeding, any of the RMP traits can be used instead of MY. However, where independence from DMI is desired, RMPR should be a trait worth considering.
Assuntos
Ração Animal , Composição Corporal/fisiologia , Bovinos/crescimento & desenvolvimento , Bovinos/metabolismo , Metano/metabolismo , Fenótipo , Envelhecimento/metabolismo , Animais , Dieta/veterinária , Ingestão de Alimentos/fisiologia , Feminino , Efeito Estufa , Masculino , Músculo Esquelético/diagnóstico por imagem , Sistema Respiratório/metabolismo , UltrassonografiaRESUMO
Residual feed intake (RFI) has been adopted in Australia for the purpose of genetic improvement in feed efficiency in beef cattle. RFI is the difference between the observed feed intake of an animal and the predicted feed intake based on its size and growth rate over a test period. Gene expression of eight candidate genes (AHSG, GHR, GSTM1, INHBA, PCDH19, S100A10, SERPINI2 and SOD3), previously identified as differentially expressed between divergent lines of high- and low-RFI animals, was measured in an unselected population of 60 steers from the Angus Society Elite Progeny Test Program using quantitative real-time PCR. Results showed that the levels of gene expression were significantly correlated with RFI. The genes explain around 33.2% of the phenotypic variance in RFI, and prediction equations using the expression data are reasonably accurate estimators of RFI. The association of these genes with economically important traits, such as other feed efficiency-related traits and fat, growth and carcass traits, was investigated as well. The expression of these candidate genes was significantly correlated with feed conversion ratio and daily feed intake, which are highly associated with RFI, suggesting a functional role for these genes in modulating feed utilisation. The expression of these genes did not show any association with average daily gain, eye muscle area and carcass composition.
Assuntos
Cruzamento , Bovinos/crescimento & desenvolvimento , Bovinos/genética , Ingestão de Alimentos/genética , Ração Animal , Animais , Composição Corporal/genética , Masculino , Carne/análise , Fenótipo , Aumento de Peso/genéticaRESUMO
The aim of this study was to assess the accuracy of genomic predictions for 19 traits including feed efficiency, growth, and carcass and meat quality traits in beef cattle. The 10,181 cattle in our study had real or imputed genotypes for 729,068 SNP although not all cattle were measured for all traits. Animals included Bos taurus, Brahman, composite, and crossbred animals. Genomic EBV (GEBV) were calculated using 2 methods of genomic prediction [BayesR and genomic BLUP (GBLUP)] either using a common training dataset for all breeds or using a training dataset comprising only animals of the same breed. Accuracies of GEBV were assessed using 5-fold cross-validation. The accuracy of genomic prediction varied by trait and by method. Traits with a large number of recorded and genotyped animals and with high heritability gave the greatest accuracy of GEBV. Using GBLUP, the average accuracy was 0.27 across traits and breeds, but the accuracies between breeds and between traits varied widely. When the training population was restricted to animals from the same breed as the validation population, GBLUP accuracies declined by an average of 0.04. The greatest decline in accuracy was found for the 4 composite breeds. The BayesR accuracies were greater by an average of 0.03 than GBLUP accuracies, particularly for traits with known genes of moderate to large effect mutations segregating. The accuracies of 0.43 to 0.48 for IGF-I traits were among the greatest in the study. Although accuracies are low compared with those observed in dairy cattle, genomic selection would still be beneficial for traits that are hard to improve by conventional selection, such as tenderness and residual feed intake. BayesR identified many of the same quantitative trait loci as a genomewide association study but appeared to map them more precisely. All traits appear to be highly polygenic with thousands of SNP independently associated with each trait.
Assuntos
Cruzamento/métodos , Bovinos/fisiologia , Genótipo , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Polimorfismo de Nucleotídeo Único , Animais , Teorema de Bayes , Bovinos/genética , Bovinos/crescimento & desenvolvimento , Comportamento Alimentar , Feminino , Modelos Lineares , Masculino , Carne/análise , Análise de Sequência com Séries de Oligonucleotídeos/veterinária , Locos de Características Quantitativas , Característica Quantitativa Herdável , Especificidade da EspécieRESUMO
BACKGROUND: Organ transplant recipients have an increased risk of skin cancers. A specialist dermatology clinic for renal transplant recipients (RTRs) was established in 2005. OBJECTIVES: To analyse the type and incidence of skin cancers in prevalent patients in the West of Scotland after renal transplant, and to analyse the impact of the time since transplant and the immunosuppression regimen. METHODS: Skin cancer data for RTRs attending the transplant dermatology clinic over a 38-month period were collected and recorded in the West of Scotland electronic renal patient record. Skin cancer data were intrinsically linked to each individual's transplant and immunosuppression data. RESULTS: Overall, 610 patients attended. The median follow-up time from the date of first transplant was 10 years. Ninety-three patients (15.2%) had experienced a total of 368 skin cancers since transplant, and the prevalence increased with time since transplant. Basal cell carcinomas (BCCs) occurred in 74 patients (12.1%) and squamous cell carcinomas (SCCs) in 42 patients (6.9%). Three patients (0.5%) had experienced a melanoma. The SCC:BCC ratio was 0.7. Survival analysis showed significant reduction in the time to develop skin cancer in patients transplanted from 1995 onwards (P < 0.0001) and in patients who had been on triple immunosuppressant therapy at 1 year after transplant, compared with dual therapy (P < 0.0001). CONCLUSIONS: This is the first study of skin cancer in prevalent Scottish RTRs. The incidence of skin cancer is high and appears to have a direct relationship to the overall burden of immunosuppression. The SCC:BCC ratio, which is lower than reports from other centres, deserves further scrutiny.
Assuntos
Carcinoma Basocelular/etiologia , Carcinoma de Células Escamosas/etiologia , Transplante de Rim , Melanoma/etiologia , Neoplasias Cutâneas/etiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Terapia de Imunossupressão , Imunossupressores/administração & dosagem , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Escócia/epidemiologia , Adulto JovemRESUMO
Feed efficiency is an economically important trait in beef production. It can be measured as residual feed intake. This is the difference between actual feed intake recorded over a test period and the expected feed intake of an animal based on its size and growth rate. DNA-based marker-assisted selection would help beef breeders to accelerate genetic improvement for feed efficiency by reducing the generation interval and would obviate the high cost of measuring residual feed intake. Although numbers of quantitative trait loci and candidate genes have been identified with the advance of molecular genetics, our understanding of the physiological mechanisms and the nature of genes underlying residual feed intake is limited. The aim of the study was to use global gene expression profiling by microarray to identify genes that are differentially expressed in cattle, using lines genetically selected for low and high residual feed intake, and to uncover candidate genes for residual feed intake. A long-oligo microarray with 24 000 probes was used to profile the liver transcriptome of 44 cattle selected for high or low residual feed intake. One hundred and sixty-one unique genes were identified as being differentially expressed between animals with high and low residual feed intake. These genes were involved in seven gene networks affecting cellular growth and proliferation, cellular assembly and organization, cell signalling, drug metabolism, protein synthesis, lipid metabolism, and carbohydrate metabolism. Analysis of functional data using a transcriptional approach allows a better understanding of the underlying biological processes involved in residual feed intake and also allows the identification of candidate genes for marker-assisted selection.
Assuntos
Bovinos/genética , Ingestão de Alimentos/genética , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Fígado/metabolismo , Locos de Características Quantitativas , Ração Animal , Animais , Bovinos/metabolismo , Masculino , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da PolimeraseRESUMO
A genome wide-association study for production traits in cattle was carried out using genotype data from the 10K Affymetrix (Santa Clara, CA) and the 50K Illumina (San Diego, CA) SNP chips. The results for residual feed intake (RFI), BW, and hip height in 3 beef breed types (Bos indicus, Bos taurus, and B. indicus × B. taurus), and for stature in dairy cattle, are presented. The aims were to discover SNP associated with all traits studied, but especially RFI, and further to test the consistency of SNP effects across different cattle populations and breed types. The data were analyzed within data sets and within breed types by using a mixed model and fitting 1 SNP at a time. In each case, the number of significant SNP was more than expected by chance alone. A total of 75 SNP from the reference population with 50K chip data were significant (P < 0.001) for RFI, with a false discovery rate of 68%. These 75 SNP were mapped on 24 different BTA. Of the 75 SNP, the 9 most significant SNP were detected on BTA 3, 5, 7, and 8, with P ≤ 6.0 × 10(-5). In a population of Angus cattle divergently selected for high and low RFI and 10K chip data, 111 SNP were significantly (P < 0.001) associated with RFI, with a false discovery rate of 7%. Approximately 103 of these SNP were therefore likely to represent true positives. Because of the small number of SNP common to both the 10K and 50K SNP chips, only 27 SNP were significantly (P < 0.05) associated with RFI in the 2 populations. However, other chromosome regions were found that contained SNP significantly associated with RFI in both data sets, although no SNP within the region showed a consistent effect on RFI. The SNP effects were consistent between data sets only when estimated within the same breed type.
Assuntos
Criação de Animais Domésticos/métodos , Bovinos/crescimento & desenvolvimento , Bovinos/genética , Perfilação da Expressão Gênica , Genoma , Animais , Comportamento Alimentar , Genótipo , Desequilíbrio de Ligação , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Nonmelanoma skin cancer (NMSC) has been linked to cutaneous human papillomaviruses of the genus beta (betaPV). OBJECTIVES: We sought to assess the presence of betaPV in NMSC biopsies from a group of Scottish skin cancer patients, both immunocompetent (IC) patients and immunosuppressed (IS) organ transplant recipients. METHODS: One hundred and twenty-one paraffin-embedded skin tumours (27 actinic keratosis, 41 intraepidermal carcinoma, 53 squamous cell carcinoma) and 11 normal skin samples were analysed for the presence of betaPV by a polymerase chain reaction-reverse hybridization assay designed to detect the presence of the 25 known betaPV genotypes. RESULTS: In IC patients, betaPV was detected in 30 of 59 (51%) tumours and two of 11 (18%) normal skin samples (P = 0.046). In IS patients, betaPV was found in 27 of 62 (44%) tumours; no normal skin samples were available for comparison. The most frequently found genotypes were HPV-24, HPV-15 and HPV-38. Of those tumours infected with betaPV, 28 of 57 (49%) were infected with more than one genotype (range 2-8). Tumours from IS patients were from a younger age group (mean age 57.4 years) than IC patients (mean age 73.8 years). Multiple infections were more common in tumours from IC patients (21 of 30; 70%) compared with those from IS patients (seven of 27; 26%) (P < 0.001). In the IC group, age did not appear to influence the distribution of single and multiple infections whereas in IS patients the proportion of multiple infections to single infections increased with age. There were no multiple infections in normal skin. CONCLUSIONS: A wide spectrum of betaPV types was detected in our samples. Further characterization of betaPV in vivo is needed in order to determine the mechanisms by which the virus contributes to cutaneous carcinogenesis.
Assuntos
Betapapillomavirus/isolamento & purificação , Hospedeiro Imunocomprometido , Transplante de Órgãos , Infecções por Papillomavirus/virologia , Neoplasias Cutâneas/virologia , Idoso , Betapapillomavirus/classificação , Betapapillomavirus/genética , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Infecções por Papillomavirus/epidemiologia , Reação em Cadeia da Polimerase , Escócia/epidemiologiaRESUMO
Residual feed intake (RFI) is a measure of feed efficiency that is independent of level of production, such as size and growth rate in beef cattle, and thus is a useful new trait for studying the physiological mechanisms underlying variation in feed efficiency. Five major physiological processes are likely to contribute to variation in RFI, these being processes associated with intake of feed, digestion of feed, metabolism (anabolism and catabolism associated with and including variation in body composition), physical activity, and thermoregulation. Studies on Angus steers following divergent selection for RFI estimated that heat production from metabolic processes, body composition, and physical activity explained 73% of the variation in RFI. The proportions of variation in RFI that these processes explain are protein turnover, tissue metabolism and stress (37%); digestibility (10%); heat increment and fermentation (9%); physical activity (9%); body composition (5%); and feeding patterns (2%). Other studies in cattle and studies in poultry similarly found these processes to be important in explaining RFI. The physiological mechanisms identified so far are based on very few studies, some of which have small sample sizes. The genomic basis to variation in these physiological processes remains to be determined. Early studies have shown many hundred genes to be associated with differences in RFI, perhaps in hindsight not surprising given the diversity of physiological processes involved. Further research is required to better understand the mechanisms responsible for the variation in RFI in target populations and to marry the physiological information with molecular genetics information that will become the basis for commercial tests for genetically superior animals.
Assuntos
Fenômenos Fisiológicos da Nutrição Animal , Ingestão de Alimentos/fisiologia , Animais , Composição Corporal , Regulação da Temperatura Corporal , GenômicaAssuntos
Sarda Melanótica de Hutchinson/patologia , Neoplasias Cutâneas/patologia , Pele/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia/métodos , Feminino , Humanos , Sarda Melanótica de Hutchinson/terapia , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde/normas , Estudos Retrospectivos , Distribuição por Sexo , Neoplasias Cutâneas/terapia , Adulto JovemRESUMO
Seventy-six Angus steers chosen from breeding lines divergently selected for residual feed intake (RFI) were studied to quantify the relationship between RFI and the daily rate of methane production (MPR). A 70-d feeding test using a barley-based ration was conducted in which the voluntary DMI, feeding characteristics, and BW of steers were monitored. The estimated breeding value (EBV) for RFI (RFI(EBV)) for each steer had been calculated from 70-d RFI tests conducted on its parents. Methane production rate (g/d) was measured on each steer using SF(6) as a tracer gas in a series of 10-d measurement periods. Daily DMI of steers was lower during the methane measurement period than when methane was not being measured (11.18 vs. 11.88 kg; P = 0.001). A significant relationship existed between MPR and RFI when RFI (RFI(15d)) was estimated over the 15 d when steers were harnessed for methane collection (MPR = 13.3 x RFI(15d) + 179; r(2) = 0.12; P = 0.01). Animals expressing lower RFI had lower daily MPR. The relationship established between MPR and RFI(15d) was used to calculate a reduction in daily methane emission of 13.38 g accompanied a 1 kg/d reduction in RFI(EBV) in cattle consuming ad libitum a diet of 12.1 MJ of ME/kg. The magnitude of this emission reduction was between that predicted on the basis of intake reduction alone (18 g x d(-1) x kg of DMI(-1)) and that predicted by a model incorporating steer midtest BW and level of intake relative to maintenance (5 g x d(-1) x kg of DMI(-1)). Comparison of data from steers exhibiting the greatest (n = 10) and lowest (n = 10) RFI(15d) showed the low RFI(15d) group to not only have lower MPR (P = 0.017) but also reduced methane cost of growth (by 41.2 g of CH(4)/kg of ADG; P = 0.09). Although the opportunity to abate livestock MPR by selection against RFI seems great, RFI explained only a small proportion of the observed variation in MPR. A genotype x nutrition interaction can be anticipated, and the MPR:RFI(EBV) relationship will need to be defined over a range of diet types to account for this.
Assuntos
Bovinos/metabolismo , Comportamento Alimentar/fisiologia , Metano/metabolismo , Animais , Cruzamento , Bovinos/genética , Genótipo , MasculinoRESUMO
BACKGROUND: Topical 5-fluorouracil (5-FU) cream is widely used in the treatment of actinic keratoses (AKs) but the optimum treatment regimen that provides efficacy while minimizing side-effects remains unclear. OBJECTIVES: A randomized trial to compare the efficacy and side-effects of daily vs. weekly application of 5% 5-FU in the treatment of AKs of the scalp and face. PATIENTS/METHODS: Twenty patients were recruited and randomized to two groups. Group 1 (13 patients) applied 5% 5-FU twice daily for 3 weeks, group 2 (seven patients) applied 5% 5-FU twice daily for 1 day per week for 12 weeks. Patients were reviewed at weeks 3, 12, 24 and 52. At each review a lesion count and lesion map were completed and patients were asked to score efficacy and inflammation. RESULTS: At week 0 the median lesion count was the same in both groups, 17.5 lesions. At 12 weeks the median lesion count in group 1 had fallen to 0 where it remained for the duration of follow-up. In group 2 the median lesion count fell to 6 at 12 weeks, 5.5 at 24 weeks and was 3 at 52 weeks. The difference in the lesion count was significant at all time points after week 0: P < 0.05 at weeks 12 and 52, and P < 0.01 at week 24. The mean inflammation score was higher in patients clear of AKs at 12 weeks compared with those who had not cleared, 3.8 compared with 1.9. This difference was statistically significant (P < 0.05) suggesting that inflammation is necessary for efficacy. CONCLUSIONS: We conclude that daily application of 5% 5-FU cream is more effective than weekly application at clearing AKs from the scalp and face. Our results also suggest that inflammation is likely to be required to achieve a therapeutic effect.
Assuntos
Antimetabólitos/administração & dosagem , Dermatoses Faciais/tratamento farmacológico , Fluoruracila/administração & dosagem , Ceratose/tratamento farmacológico , Dermatoses do Couro Cabeludo/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Antimetabólitos/efeitos adversos , Antimetabólitos/uso terapêutico , Esquema de Medicação , Dermatoses Faciais/patologia , Feminino , Fluoruracila/efeitos adversos , Fluoruracila/uso terapêutico , Humanos , Ceratose/patologia , Masculino , Pessoa de Meia-Idade , Dermatoses do Couro Cabeludo/patologiaRESUMO
BACKGROUND: Lithium carbonate is the most widely used long-term treatment for bipolar affective disorders, but its ability to trigger and exacerbate psoriasis can become a major problem in patients for whom lithium is the only treatment option. Inositol depletion underlies the action of lithium in bipolar affective disorders and there are good theoretical reasons why the use of inositol supplements might be expected to help this group of patients. OBJECTIVES: To determine whether inositol supplements improve the psoriasis of patients on lithium therapy. METHODS: Fifteen patients with psoriasis, who were taking lithium, took part in a randomized, double-blind, placebo-controlled, crossover clinical trial comparing the effect of inositol supplements with those of a placebo (lactose). Changes in the severity of their psoriasis were measured by Psoriasis Area and Severity Index scores recorded before and after the different courses of treatment. The effect of inositol supplements on the psoriasis of 11 patients who were not taking lithium was evaluated in the same way. RESULTS: The inositol supplements had a significantly beneficial effect on the psoriasis of patients taking lithium. No such effect was detected on the psoriasis of patients not on lithium. CONCLUSIONS: The use of inositol supplements is worth considering for patients with intractable psoriasis who need to continue to take lithium for bipolar affective disorders.
Assuntos
Antimaníacos/efeitos adversos , Toxidermias/tratamento farmacológico , Inositol/uso terapêutico , Carbonato de Lítio/efeitos adversos , Psoríase/induzido quimicamente , Adulto , Transtorno Bipolar/tratamento farmacológico , Estudos Cross-Over , Suplementos Nutricionais , Método Duplo-Cego , Toxidermias/etiologia , Feminino , Humanos , Masculino , Psoríase/tratamento farmacológicoRESUMO
BACKGROUND: In the current economic climate, it is important to justify the cost of treatments used in dermatology, particularly where cheaper alternatives exist. OBJECTIVES: To determine which treatment modality commonly used for Bowen's disease is associated with the lowest cost to the National Health Service. METHODS: A cost-minimization analysis was used to compare the following six treatments for Bowen's disease: cryotherapy, curettage and cautery, excision, laser ablation, photodynamic therapy and 5-fluorouracil. These are all known to have similar recurrence rates. Information regarding use of these treatment modalities was extracted from a literature review. Costs were determined from published data, average wholesale prices of medications, staff salary pay scales and health economics departments. RESULTS: The results show that, if treatment is indeed undertaken, a single lesion of Bowen's disease is most cheaply treated by curettage or excision biopsy under local anaesthetic, and most expensively treated by photodynamic therapy. The usefulness of this information has to be taken in the context of the study design, outcome measurements and base assumptions. CONCLUSIONS: Valid costing studies such as this, in conjunction with evidence of effectiveness and safety, can provide guidance for resource allocation and treatment decisions.
Assuntos
Doença de Bowen/economia , Medicina Estatal/economia , Antimetabólitos/economia , Antimetabólitos/uso terapêutico , Biópsia/economia , Doença de Bowen/terapia , Análise Custo-Benefício , Custos e Análise de Custo , Crioterapia/economia , Curetagem/economia , Fluoruracila/economia , Fluoruracila/uso terapêutico , Humanos , Terapia a Laser/economia , Fotoquimioterapia/economiaRESUMO
Records on 1,180 young Angus bulls and heifers involved in performance tests were used to estimate genetic and phenotypic parameters for feed intake, feed efficiency, and other postweaning traits. The mean age was 268 d at the start of the performance test, which comprised 21-d adjustment and 70-d test periods. Traits studied included 200-d weight, 400-d weight, scrotal circumference, ultrasonic measurements of rib and rump fat depths and longissimus muscle area, ADG, metabolic weight, daily feed intake, feed conversion ratio, and residual feed intake. For all traits except the last five, additional data from the Angus Society ofAustralia pedigree and performance database were included, which increased the number of animals to 27,229. Genetic (co)variances were estimated by REML using animal models. Direct heritability estimates for 200-d weight, 400-d weight, rib fat depth, ADG, feed conversion,and residual feed intake were 0.17 +/- 0.03, 0.27 +/- 0.03, 0.35 +/- 0.04, 0.28 +/- 0.04, 0.29 +/- 0.04, and 0.39 +/- 0.03, respectively. Feed conversion ratio was genetically (r(g) = 0.66 ) and phenotypically (r(p) = 0.53) correlated with residual feed intake. Feed conversion ratio was correlated (r(g) = -0.62, r(p) = -0.74) with ADG, whereas residual feed intake was not (rg = -0.04, r(p) = -0.06). Genetically, both residual feed intake and feed conversion ratio were negatively correlated with direct effects of 200-d weight (r(g) = -0.45 and -0.21) and 400-d weight (r(g) = -0.26 and -0.09). The correlations between the remaining traits and the feed efficiency traits were near zero, except between feed intake and feed conversion ratio (r(g) = 0.31, r(p) = 0.23), feed intake and residual feed intake (r(g) = 0.69, r(p) = 0.72), and rib fat depth and residual feed intake (r(g) = 0.17, r(p) = 0.14). These results indicate that genetic improvement in feed efficiency can be achieved through selection and, in general, correlated responses in growth and the other postweaning traits will be minimal.
Assuntos
Tecido Adiposo/anatomia & histologia , Peso Corporal/genética , Bovinos/genética , Ingestão de Alimentos/genética , Ingestão de Energia/genética , Músculo Esquelético/anatomia & histologia , Tecido Adiposo/diagnóstico por imagem , Fatores Etários , Ração Animal , Animais , Peso Corporal/fisiologia , Cruzamento , Bovinos/crescimento & desenvolvimento , Bovinos/fisiologia , Ingestão de Alimentos/fisiologia , Ingestão de Energia/fisiologia , Feminino , Variação Genética , Genótipo , Masculino , Modelos Genéticos , Músculo Esquelético/diagnóstico por imagem , Fenótipo , Fatores de Tempo , Ultrassonografia , DesmameRESUMO
Bath-PUVA is an alternative to oral-PUVA for the treatment of psoriasis. This study compares the effectiveness of the two methods in two groups, each consisting of 17 patients with plaque psoriasis. Three patients who failed to improve with oral-PUVA were transferred to bath-PUVA and subsequently cleared. Another seven patients who returned with a further episode of psoriasis received the alternative treatment; this gave a group of 10 patients in whom a cross-over comparison was possible. In both comparisons bath-PUVA was as effective as, or more effective than, oral-PUVA and required, overall, less than 50% of the total UVA, although this saving was not as great as in previous reports. Bath-PUVA caused fewer immediate problems and was preferred by many patients. It is suitable for those taking other systemic medications and we recommend it as a valuable therapeutic option that should be available at all treatment centres.