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1.
Animal ; 18(7): 101199, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38897107

RESUMO

Demand for animal-source foods and livestock feed are forecast to increase across sub-Saharan Africa. In this context, there is a need to estimate the availability of livestock feed to support decision-making at local, sub-national and national levels. In this study, we assess feed balances for ruminant livestock in Ethiopia and Burkina Faso. Feed availability was estimated using remotely sensed products and detailed feed composition data. Feed requirements were estimated for maintenance, growth, lactation, gestation and locomotion using a data-intensive model. Biomass available as animal feed was estimated to be 8.6 tonnes of DM per hectare in the Ethiopian highlands and midlands, 3.2 tonnes DM per hectare in the Ethiopian lowlands, 2.9 tonnes DM per hectare in Burkina Faso's Sudanian agro-ecological zone and 1.0 tonne DM per hectare in the Sahel. The energy requirements of lactating cows were estimated to be 62.1 Megajoules (MJs) per animal per day in the Ethiopian highlands and midlands, 62.7 MJ in the Ethiopian lowlands, 88.5 MJ in Burkina Faso's Sudanian agro-ecological zone and 53.1 MJ per animal per day in the Sahel. Feed scarcity hotspots are most prominently located in the Ethiopian highlands and the Sahelian agro-ecological zone of Burkina Faso. Demand-side policy and investment initiatives can address hotspots by influencing herd sizes, nutritional requirements and herd mobility. Supply-side policy and investment initiatives can secure existing feed resources, develop new sources of feed and incentivise trade in feed resources. Improving feed balances will be of value to decision-makers with the aims of optimising livestock productivity, minimising exposure to climatic shocks and minimising greenhouse gas emission intensity.

2.
J Dairy Sci ; 106(1): 653-663, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36400618

RESUMO

Dairy cows are predisposed to diseases during the postpartum period. Dystocia has been associated with increased risk for disease, which is likely the result of increased tissue trauma and stress during the prolonged parturition. To attenuate the inflammatory response seen in dystocic animals and improve well-being, we assessed the effects of a glucocorticoid, dexamethasone administered within 12 h after calving. Dystocia was defined as a difficult birth resulting in a prolonged calving (≥70 min after the amniotic sac appears) and was monitored through 3 video cameras in the close-up dry-cow pen. Cows meeting the dystocia definition were randomly assigned to receive a single intramuscular injection of either dexamethasone (DEX; 0.1 mg/kg of body weight; n = 43) or saline (CON, n = 44) within 12 h following a dystocic calving. Serum haptoglobin, blood ß-hydroxybutyrate (BHB) concentrations, body temperature, and several behaviors were measured for the first 7 d postpartum. Additionally, milk production and components for the first 120 d were recorded. Using a mixed model, the fixed effects of treatment, parity, calving assistance, and time, along with 2- and 3-way interactions, were analyzed with cow as a random effect. We observed that primiparous DEX cows had greater serum haptoglobin concentrations on d 3 and d 7 postpartum compared with primiparous CON cows. There was no difference between treatment groups for blood BHB concentrations and body temperature. Behavior was altered between treatments, with DEX cows having reduced activity for the first week postpartum, as well as less restlessness and increased lying times on some of the days following calving. Treatment interacted with time for milk yield, such that DEX cows produced 2.7 kg/d less milk than CON cows for the first month following calving. The administration of dexamethasone resulted in changes in behavioral measurements, which could suggest a reduction in discomfort; however, due to the reduction in milk yield for the first month following calving, DEX administration may not be applicable for typical farm use. Additional research is needed to investigate treatments for cows experiencing dystocia without detrimental effects on milk yield.


Assuntos
Doenças dos Bovinos , Distocia , Gravidez , Feminino , Bovinos , Animais , Lactação/fisiologia , Haptoglobinas , Leite , Período Pós-Parto , Paridade , Ácido 3-Hidroxibutírico , Distocia/tratamento farmacológico , Distocia/veterinária , Dexametasona/farmacologia , Doenças dos Bovinos/tratamento farmacológico
3.
Anim Feed Sci Technol ; 262: 114419, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32255896

RESUMO

Feed scarcity is a major challenge for livestock production in West Africa, especially during the dry season when grass quality and quantity on grazing lands are inadequate. In the dry season, crop residues are a key source of livestock feed. The residues of grain legumes, also known as grain legume fodders (GLFs), are stored and traded for feeding in the dry season. The objectives of our experiment were to evaluate the effects of storage conditions and duration on dry matter (DM) and nutritional quality of GLFs, and to assess the risk of aflatoxin in stored groundnut fodder. The experiment was designed as a factorial trial with 18 treatment combinations with four replicates (4 farms). The treatments included: 3 types of GLFs (cowpea, groundnut and soybean fodder), 3 types of storage locations (rooftop, room and tree-fork) and 2 types of packaging (packed in polythene sacks and unpacked but tied with rope). Over a 120 day storage period, DM quantity reduced by an average of 24 % across all storage conditions, showing a range from 14 % in the best condition (sacks and rooms) to 35 % in the worst condition (bundles tied with rope and stored on rooftops or tree-forks). Soybean fodder had no leaves, the lowest crude protein content (CP) and organic matter digestibility (OMD), and the highest content of cell wall components compared to cowpea and groundnut fodder. These nutritional quality parameters in soybean fodder hardly changed during storage. Cowpea and groundnut fodder showed a decrease in leaf-to-stem ratio (LSR), CP and OMD, and an increase in the content of cell wall components during storage, but their nutritional value remained better than that of soybean fodder. Storage in sacks resulted in less DM loss, in less reduction of LSR and in a smaller increase of the content of cell wall components than storage of bundles tied with rope. Our study shows that the DM loss, the decrease in LSR, and the increase in the content of cell wall components can be prevented partly by storing GLFs in sacks instead of tying bundles with rope, and to a minor extent by storing in rooms instead of in the open air. Aflatoxin was not detectable in the groundnut fodder samples. Our results highlight that attention to storage conditions can improve the feeding value of GLFs which are key for livestock nutrition during the dry season.

4.
East Afri Agric For J ; 83(4): 351-367, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32309420

RESUMO

To understand farmers' preference and perceptions of breed attributes, breeding and feeding practices, 419 households in western Kenya were interviewed in a cross-sectional survey. Respondents scored their preference for cattle breeds, traits and breeding methods on a scale of 1 (most preferred) to 5 (least preferred). Preferences were compared using multinomial logistic regression models on weighted scores. The Ayrshire breed was most preferred followed by the Friesian. Using hardship tolerance as a reference trait, the Friesian was preferred 4.86 times more for high milk production and Ayrshire, Jersey and Guernsey breeds 4.61, 4.60 and 4.18 times (p < 0.01) more, respectively, for milk fat content. The Ayrshire was preferred 4.16 times more for its perceived low feed requirement and 1.22 times more (p < 0.01) for resistance to diseases. Friesian was the only breed preferred (3.18 times more) (p < 0.01) for high growth rate of calves. Artificial insemination (AI) was the breeding method of choice, but majority (>68%) of respondents used natural mating, because it was readily available and cheaper. The current study highlights the importance of taking into account farmers' objectives and the production environment when designing breed improvement programmes and recommends packaging of breeding together with feeding interventions.

5.
Animal ; 12(s2): s199-s209, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30139396

RESUMO

The role of herbivorous livestock in supporting the sustainability of the farming systems in which they are found is complex and sometimes conflicting. In Sub-Saharan Africa (SSA), the integration of livestock into farming systems is important for sustainable agriculture as the recycling of nutrients for crop production through returns of animal manure is a central element of the dominant mixed crop-livestock systems. Sustainable agriculture has been widely advocated as the main practical pathway to address the challenge of meeting the food needs of the rapidly growing population in SSA while safeguarding the needs of future generations. The objective of this paper is to review the state of knowledge of the role of herbivores in sustainable intensification of key farming systems in SSA. The pathways to sustainable agriculture in SSA include intensification of production and livelihood diversification. Sustainable agricultural practices in SSA have focused on intensification practices which aim to increase the output : input ratio through increasing use of inputs, introduction of new inputs or use of existing inputs in a new way. Intensification of livestock production can occur through increased and improved fodder availability, genetic production gains, improved crop residue use and better nutrient recycling of manure. Livestock deliver many 'goods' in smallholder farming systems in SSA including improving food and nutrition security, increased recycling of organic matter and nutrients and the associated soil fertility amendments, adding value to crop residues by turning them into nutrient-rich foods, income generation and animal traction. Narratives on livestock 'bads' or negative environmental consequences have been largely shaped by the production conditions in the Global North but livestock production in SSA is a different story. In SSA, livestock are an integral component of mixed farming systems and they play key roles in supporting the livelihoods of much of the rural population. None-the-less, the environmental consequences of livestock production on the continent cannot be ignored. To enhance agricultural sustainability in SSA, the challenge is to optimize livestock's role in the farming systems by maximizing livestock 'goods' while minimizing the 'bads'. This can be through better integration of livestock into the farming systems, efficient nutrient management systems, and provision of necessary policy and institutional support.


Assuntos
Agricultura , Ração Animal , Abastecimento de Alimentos , Ruminantes , Desenvolvimento Sustentável , África Subsaariana , Animais , Produção Agrícola , Fazendas , Herbivoria , Gado
6.
Trop Anim Health Prod ; 49(7): 1415-1422, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28681285

RESUMO

The objective of this study was to determine the effect of supplementing increasing levels of dried tagasaste (Chamaecytisus palmensis) leaf on the nutrition and performance of sheep fed a basal diet of barley straw. The study had four treatments, which involved supplementation of dried tagasaste leaf at 100, 200, 300, and 400 g/day. Twenty-four yearling Menz sheep (weight 17 ± 0.83 kg) were assigned to one of the four treatments in a randomized complete block design. The experiment comprised a feeding trial lasting for 90 days, a digestibility trial, and carcass evaluation using all animals. Samples of the feed consumed, refused, and feces were analyzed for nutrients. Intake and digestibility of dry matter (DM) and nutrients increased linearly (P < 0.001) as tagasaste supplementation increased from 100 to 400 g/day. Similarly, average daily body weight gain increased linearly (P < 0.001) from 20 to 73 g/day, feed conversion efficiency from 0.04 to 0.10, and dressing percentage from 40 to 48%, as the supplementation increased from 100 to 400 g/day. Proportion of tagasaste leaf in the diet increased from 20 to 50%, while the ratio of neutral detergent fiber (NDF) to crude protein (CP) decreased from 7.9 to 5.3, as the level of supplementation increased. It was thus concluded that supplementation of dried tagasaste leaf up to 50% of the diet DM, resulting in a NDF:CP ratio of 5.3, produces no deleterious effects on the performance of sheep, and inclusion to this level can be applied for superior growth performance and carcass yield in sheep fed crop residue-based diets.


Assuntos
Digestão/efeitos dos fármacos , Fabaceae/química , Comportamento Alimentar , Estado Nutricional/efeitos dos fármacos , Ovinos/fisiologia , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Dieta/veterinária , Suplementos Nutricionais/análise , Relação Dose-Resposta a Droga , Masculino , Folhas de Planta/química , Distribuição Aleatória
7.
PLoS One ; 12(5): e0175628, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28472078

RESUMO

We show theoretically that the hypothesis of criticality as a theory of long-range fluctuation in the human brain may be distinguished from the theory of passive filtering on the basis of macroscopic neuronal signals such as the electroencephalogram, using novel theory of narrowband amplitude time-series at criticality. Our theory predicts the division of critical activity into meta-universality classes. As a consequence our analysis shows that experimental electroencephalography data favours the hypothesis of criticality in the human brain.


Assuntos
Encéfalo/fisiologia , Neurônios/fisiologia , Encéfalo/citologia , Eletroencefalografia , Humanos
8.
Trop Anim Health Prod ; 49(4): 681-690, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28224262

RESUMO

While there is a general consensus that using dairy technologies, such as improved breeds of dairy cows, can substantially increase farm productivity and income, adoption of such technologies has been generally low in developing countries. The underlying reasons for non-adoption of beneficial technologies in the dairy sector are not fully understood. In this study, we characterised adopters and non-adopters of dairy technologies in Ethiopia and Kenya based on farmers' resources ownership in order to identify why many farmers in Ethiopia and Kenya have not adopted improved dairy technologies. As compared to non-adopters, farmers who adopt dairy technology own relatively more farm resources. The result signals that differences in resource endowments could lead to divergent technology adoption scenarios. Results show that a higher proportion of sample smallholders in Kenya have adopted dairy technologies than those in Ethiopia. Except for the use of veterinary services, fewer than 10% of sample farmers in Ethiopia have adopted dairy technologies-less than half the number of adopters in Kenya. The higher level of dairy technology adoption in Kenya can be ascribed partly to the long history of dairy development, including improvements in the value chain for the delivery of inputs, services and fluid milk marketing. Interventions that deal with the constraints related to access to farm resources and input and output markets could facilitate uptake of dairy technology in developing countries.


Assuntos
Indústria de Laticínios/métodos , Países em Desenvolvimento , Tecnologia/tendências , Criação de Animais Domésticos , Animais , Cruzamento , Bovinos , Indústria de Laticínios/estatística & dados numéricos , Etiópia , Feminino , Humanos , Quênia , Masculino , Leite , Propriedade , Inquéritos e Questionários , Tecnologia/estatística & dados numéricos
10.
Animal ; 11(5): 881-889, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28031076

RESUMO

Evaluation of lifetime productivity of individual animals in response to various interventions allows assessment of long-term investment opportunities for farmers. In order to gain a better understanding of promising feed interventions for improvement of small ruminant production in Southwestern Nigeria, a dynamic modelling approach was used to explore the effect of different feeding strategies on the lifetime productivity of West African Dwarf (WAD) goats. Modifications were made to the current version of Livestock Simulator developed for cattle production to simulate goat production systems particularly for WAD goats. Effects of changes in input parameters (quality of feed and potential adult weight) confirmed the sensitivity of the modelled weight development and reproductive performance. The values of simulated model outputs corresponded well with observed values for most of the variables, except for the pre-weaning mortality rate in the cut-and-carry system where a wide discrepancy between simulated (2.1%) and observed (23%) data was found. The scenario analysis showed that simulated goats in the free grazing system attained sexual maturity and kidded much later than those in the grazing with supplementation and the cut-and-carry systems. The simulated results suggested that goats require supplementation with protein and energy sources, in order to promote lifetime productivity, early sexual maturity and higher birth weight. In terms of economic returns based on feed cost alone, the moderately intense system produced the most profit. We therefore conclude that grazing with adequate supplementation using farm-generated feed resources offers an opportunity for improving smallholder goat production systems in West Africa.


Assuntos
Criação de Animais Domésticos/métodos , Cabras/fisiologia , Animais , Modelos Teóricos , Nigéria
11.
Neuroimage ; 141: 291-303, 2016 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-27402598

RESUMO

Ongoing neuronal oscillations are pivotal in brain functioning and are known to influence subjects' performance. This modulation is usually studied on short time scales whilst multiple time scales are rarely considered. In our study we show that Long-Range Temporal Correlations (LRTCs) estimated from the amplitude of EEG oscillations over a range of time-scales predict performance in a complex sensorimotor task, based on Brain-Computer Interfacing (BCI). Our paradigm involved eighty subjects generating covert motor responses to dynamically changing visual cues and thus controlling a computer program through the modulation of neuronal oscillations. The neuronal dynamics were estimated with multichannel EEG. Our results show that: (a) BCI task accuracy may be predicted on the basis of LRTCs measured during the preceding training session, and (b) this result was not due to signal-to-noise ratio of the ongoing neuronal oscillations. Our results provide direct empirical evidence in addition to previous theoretical work suggesting that scale-free neuronal dynamics are important for optimal brain functioning.


Assuntos
Ritmo alfa/fisiologia , Interfaces Cérebro-Computador , Córtex Cerebral/fisiologia , Imaginação/fisiologia , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Percepção Visual/fisiologia , Adulto , Mapeamento Encefálico/métodos , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Prognóstico , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de Tempo
12.
Sci Rep ; 6: 27089, 2016 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-27250630

RESUMO

We show that widely used approaches in statistical physics incorrectly indicate the existence of power-law cross-correlations between financial stock market fluctuations measured over several years and the neuronal activity of the human brain lasting for only a few minutes. While such cross-correlations are nonsensical, no current methodology allows them to be reliably discarded, leaving researchers at greater risk when the spurious nature of cross-correlations is not clear from the unrelated origin of the time series and rather requires careful statistical estimation. Here we propose a theory and method (PLCC-test) which allows us to rigorously and robustly test for power-law cross-correlations, correctly detecting genuine and discarding spurious cross-correlations, thus establishing meaningful relationships between processes in complex physical systems. Our method reveals for the first time the presence of power-law cross-correlations between amplitudes of the alpha and beta frequency ranges of the human electroencephalogram.

13.
PLoS One ; 11(6): e0157257, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27336162

RESUMO

We present a novel, quantitative view on the human athletic performance of individual runners. We obtain a predictor for running performance, a parsimonious model and a training state summary consisting of three numbers by application of modern validation techniques and recent advances in machine learning to the thepowerof10 database of British runners' performances (164,746 individuals, 1,417,432 performances). Our predictor achieves an average prediction error (out-of-sample) of e.g. 3.6 min on elite Marathon performances and 0.3 seconds on 100 metres performances, and a lower error than the state-of-the-art in performance prediction (30% improvement, RMSE) over a range of distances. We are also the first to report on a systematic comparison of predictors for running performance. Our model has three parameters per runner, and three components which are the same for all runners. The first component of the model corresponds to a power law with exponent dependent on the runner which achieves a better goodness-of-fit than known power laws in the study of running. Many documented phenomena in quantitative sports science, such as the form of scoring tables, the success of existing prediction methods including Riegel's formula, the Purdy points scheme, the power law for world records performances and the broken power law for world record speeds may be explained on the basis of our findings in a unified way. We provide strong evidence that the three parameters per runner are related to physiological and behavioural parameters, such as training state, event specialization and age, which allows us to derive novel physiological hypotheses relating to athletic performance. We conjecture on this basis that our findings will be vital in exercise physiology, race planning, the study of aging and training regime design.


Assuntos
Atletas , Desempenho Atlético , Modelos Teóricos , Corrida , Algoritmos , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Corrida/fisiologia
14.
Springerplus ; 5: 63, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26839756

RESUMO

Body linear measurements, and specifically heart girth (HG), have been shown to be useful predictors of cattle liveweight. To test the accuracy of body linear measurements for predicting liveweight, crossbred dairy cattle of different genotypes were measured and weighed. A total of 352 mature cows and 100 heifers were weighed using an electronic weighing scale and measurements of HG, body length, height at withers were taken using an ordinary measuring tape and body condition scored (BCS) using a five-point scale. The animals were grouped according to genotype and age. Genotype classification was undertaken from farmer recall and by visual appraisal as 40-60, 61-80 or 81-100 % exotic (non-indigenous). Age classification was simply as mature cows or heifers. Liveweight of the animals ranged from 102 to 433 kg. Liveweight was strongly correlated with HG (r = 0.84) and body condition scores (r = 0.70) and moderately correlated with body length (r = 0.64) and height at withers (0.61). Regressing LW on HG measurements gave statistically significant (P < 0.01) equations with R(2) ranging from of 0.53 to 0.78 and residual standard deviation ranging from 18.11 to 40.50 kg. The overall model developed (adjusted R(2) = 0.71) had a prediction error of 26 kg (or 11 % of the mean) and predicted LW of over 95 % of crossbred dairy cattle in the range of 100-450 kg, regardless of age and breed group. Including BCS in the model slightly improved the model fit but not the prediction error. It was concluded that the model can be useful in making general management decisions in smallholder farms.

15.
Vet Rec ; 178(12): 292, 2016 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-26867641

RESUMO

Globally, the eradication of bovine viral diarrhoea virus (BVDV) is still in its infancy, but eradication has been, or is being, adopted by several countries or regions. Comparisons between countries' schemes allow others to assess best practice, and aggregating published results from eradication schemes provides greater statistical power when analysing data. Aggregating data requires that results derived from different testing schemes be calibrated against one another. The authors aimed to evaluate whether relationships between published BVDV test results could be created and present the outcome of a systematic literature review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The results are tabulated, providing a summary of papers where there is potential cross-calibration and a summary of the obstacles preventing such data aggregation. Although differences in measuring BVDV present barriers to academic progress, they may also affect progress within individual eradication schemes. The authors examined the time taken to retest following an initial antibody BVDV test in the Scottish eradication scheme. The authors demonstrate that retesting occurred quicker if the initial not negative test was from blood rather than milk samples. Such differences in the response of farmers/veterinarians to tests may be of interest to the design of future schemes.


Assuntos
Doença das Mucosas por Vírus da Diarreia Viral Bovina/diagnóstico , Vírus da Diarreia Viral Bovina/isolamento & purificação , Programas de Rastreamento/veterinária , Animais , Doença das Mucosas por Vírus da Diarreia Viral Bovina/epidemiologia , Doença das Mucosas por Vírus da Diarreia Viral Bovina/prevenção & controle , Bovinos , Erradicação de Doenças , Programas de Rastreamento/métodos , Escócia/epidemiologia
16.
Hum Brain Mapp ; 36(8): 2901-14, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25930148

RESUMO

Relating behavioral and neuroimaging measures is essential to understanding human brain function. Often, this is achieved by computing a correlation between behavioral measures, e.g., reaction times, and neurophysiological recordings, e.g., prestimulus EEG alpha-power, on a single-trial-basis. This approach treats individual trials as independent measurements and ignores the fact that data are acquired in a temporal order. It has already been shown that behavioral measures as well as neurophysiological recordings display power-law dynamics, which implies that trials are not in fact independent. Critically, computing the correlation coefficient between two measures exhibiting long-range temporal dependencies may introduce spurious correlations, thus leading to erroneous conclusions about the relationship between brain activity and behavioral measures. Here, we address data-analytic pitfalls which may arise when long-range temporal dependencies in neural as well as behavioral measures are ignored. We quantify the influence of temporal dependencies of neural and behavioral measures on the observed correlations through simulations. Results are further supported in analysis of real EEG data recorded in a simple reaction time task, where the aim is to predict the latency of responses on the basis of prestimulus alpha oscillations. We show that it is possible to "predict" reaction times from one subject on the basis of EEG activity recorded in another subject simply owing to the fact that both measures display power-law dynamics. The same is true when correlating EEG activity obtained from different subjects. A surrogate-data procedure is described which correctly tests for the presence of correlation while controlling for the effect of power-law dynamics.


Assuntos
Encéfalo/fisiologia , Eletroencefalografia/métodos , Atividade Motora/fisiologia , Tempo de Reação , Processamento de Sinais Assistido por Computador , Ritmo alfa , Artefatos , Eletromiografia , Dedos/fisiologia , Humanos , Estimulação Física/métodos , Limiar Sensorial , Fatores de Tempo
17.
Animal ; 9(5): 908-16, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25496957

RESUMO

Livestock production is a major consumer of fresh water, and the influence of livestock production on global fresh water resources is increasing because of the growing demand for livestock products. Increasing water use efficiency of livestock production, therefore, can contribute to the overall water use efficiency of agriculture. Previous studies have reported significant variation in livestock water productivity (LWP) within and among farming systems. Underlying causes of this variation in LWP require further investigation. The objective of this paper was to identify the factors that explain the variation in LWP within and among farming systems in Ethiopia. We quantified LWP for various farms in mixed-crop livestock systems and explored the effect of household demographic characteristics and farm assets on LWP using ANOVA and multilevel mixed-effect linear regression. We focused on water used to cultivate feeds on privately owned agricultural lands. There was a difference in LWP among farming systems and wealth categories. Better-off households followed by medium households had the highest LWP, whereas poor households had the lowest LWP. The variation in LWP among wealth categories could be explained by the differences in the ownership of livestock and availability of family labor. Regression results showed that the age of the household head, the size of the livestock holding and availability of family labor affected LWP positively. The results suggest that water use efficiency could be improved by alleviating resource constraints such as access to farm labor and livestock assets, oxen in particular.


Assuntos
Criação de Animais Domésticos/métodos , Água Doce/análise , Gado/fisiologia , Água/metabolismo , Animais , Etiópia , Chuva
18.
Theor Popul Biol ; 98: 11-8, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25220357

RESUMO

Comparisons between mass-action or "random" network models and empirical networks have produced mixed results. Here we seek to discover whether a simulated disease spread through randomly constructed networks can be coerced to model the spread in empirical networks by altering a single disease parameter - the probability of infection. A stochastic model for disease spread through herds of cattle is utilised to model the passage of an SEIR (susceptible-latent-infected-resistant) through five networks. The first network is an empirical network of recorded contacts, from four datasets available, and the other four networks are constructed from randomly distributed contacts based on increasing amounts of information from the recorded network. A numerical study on adjusting the value of the probability of infection was conducted for the four random network models. We found that relative percentage reductions in the probability of infection, between 5.6% and 39.4% in the random network models, produced results that most closely mirrored the results from the empirical contact networks. In all cases tested, to reduce the differences between the two models, required a reduction in the probability of infection in the random network.


Assuntos
Doenças dos Bovinos/transmissão , Doenças Transmissíveis/veterinária , Busca de Comunicante/veterinária , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças Transmissíveis/epidemiologia , Doenças Transmissíveis/transmissão , Simulação por Computador , Busca de Comunicante/métodos , Modelos Animais de Doenças , Modelos Teóricos
19.
Neuroimage ; 99: 377-87, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-24862080

RESUMO

Although the long-range temporal correlation (LRTC) of the amplitude fluctuations of neuronal EEG/MEG oscillations is widely acknowledged, the majority of studies to date have been performed in sensor space, disregarding the mixing effects implied by volume conduction and confounding noise. While the effect of mixing on the evaluation of evoked responses and connectivity measures has been extensively studied, there are, to date, no studies reporting on the differences in the values of the estimated Hurst exponents when moving between sensor and source space representations of the multivariate data or on the effect of noise. Such differences, if not duly acknowledged, may lead to erroneous data interpretations. We show in simulations and in theory that measuring Hurst exponents in sensor space may lead to an incomplete picture of the LRTC properties of the underlying data and that noise may significantly bias the estimate of the Hurst exponent of the underlying signal. Moreover, these predictions are confirmed in real data, where we analyze the amplitude dynamics of neuronal oscillations in the resting state from EEG data. By moving either to an independent components representation or to a source representation which maximizes the signal to noise ratio in the alpha frequency range, we observe greater variance, skewness and kurtosis over measured Hurst exponents than in sensor space. We confirm the suitability of conventional source separation methodology by introducing a novel algorithm HeMax which obtains a source maximizing the Hurst exponent in the amplitude dynamics of narrow band oscillations. Our findings imply that the long-range correlative properties of the EEG should be studied in source space, in such a way that the SNR is maximized, or at least with spatial decomposition techniques approximating source activities, rather than in sensor space.


Assuntos
Algoritmos , Eletroencefalografia/métodos , Simulação por Computador , Interpretação Estatística de Dados , Eletroencefalografia/estatística & dados numéricos , Humanos , Magnetoencefalografia/métodos , Magnetoencefalografia/estatística & dados numéricos , Processamento de Sinais Assistido por Computador , Razão Sinal-Ruído , Adulto Jovem
20.
Animal ; 7(12): 2054-62, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24103418

RESUMO

Smallholder dairy production represents a promising income generating activity for poor farmers in the developing world. Because of the perishable nature of milk, marketing arrangements for collection, distribution and sale are important for enhanced livelihoods in the smallholder dairy sector. In this study we examined the relationship between market quality and basic feeding and breeding practices at farm level. We define market quality as the attractiveness and reliability of procurement channels and associated input supply arrangements. We took as our study countries, India with its well-developed smallholder dairy sector, and Ethiopia where the smallholder dairy industry has remained relatively undeveloped despite decades of development effort. We conducted village surveys among producer groups in 90 villages across three States in India and two Regions in Ethiopia. Producer groups were stratified according to three levels of market quality - high, medium and low. Data showed that diet composition was relatively similar in India and Ethiopia with crop residues forming the major share of the diet. Concentrate feeding tended to be more prominent in high market quality sites. Herd composition changed with market quality with more dairy (exotic) cross-bred animals in high market quality sites in both India and Ethiopia. Cross-bred animals were generally more prominent in India than Ethiopia. Herd performance within breed did not change a great deal along the market quality gradient. Parameters such as calving interval and milk yield were relatively insensitive to market quality. Insemination of cross-bred cows was predominantly by artificial insemination (AI) in India and accounted for around half of cross-bred cow inseminations in Ethiopia. Data on perceptions of change over the last decade indicated that per herd and per cow productivity are both increasing in high market quality sites with a more mixed picture in medium and low-quality sites. Similarly dairy-derived income is on the increase in high market quality sites. This is accompanied by a strong increase in stall feeding at the expense of grazing. The study indicates that the first constraint to intensification of dairy production in Ethiopia is the genetic quality of the herd. There is less scope for improved AI provision in India since the cross-bred herd is mainly serviced by AI already. However, as for Ethiopia, there is considerable scope for closing yield gaps in India through improved feed use and supply. Results strongly show that well-developed markets with good procurement arrangements are key for sustainable dairy intensification.


Assuntos
Criação de Animais Domésticos/métodos , Cruzamento , Bovinos/genética , Bovinos/fisiologia , Indústria de Laticínios/métodos , Países em Desenvolvimento , Ração Animal/análise , Animais , Composição Corporal , Indústria de Laticínios/economia , Etiópia , Feminino , Índia , Lactação , Modelos Teóricos
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