Burden of disease scenarios for 204 countries and territories, 2022–2050: a forecasting analysis for the Global Burden of Disease Study 2021

Background: Future trends in disease burden and drivers of health are of great interest to policy makers and the public at large. This information can be used for policy and long-term health investment, planning, and prioritisation. We have expanded and improved upon previous forecasts produced as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) and provide a reference forecast (the most likely future), and alternative scenarios assessing disease burden trajectories if selected sets of risk factors were eliminated from current levels by 2050. Methods: Using forecasts of major drivers of health such as the Socio-demographic Index (SDI; a composite measure of lag-distributed income per capita, mean years of education, and total fertility under 25 years of age) and the full set of risk factor exposures captured by GBD, we provide cause-specific forecasts of mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) by age and sex from 2022 to 2050 for 204 countries and territories, 21 GBD regions, seven super-regions, and the world. All analyses were done at the cause-specific level so that only risk factors deemed causal by the GBD comparative risk assessment influenced future trajectories of mortality for each disease. Cause-specific mortality was modelled using mixed-effects models with SDI and time as the main covariates, and the combined impact of causal risk factors as an offset in the model. At the all-cause mortality level, we captured unexplained variation by modelling residuals with an autoregressive integrated moving average model with drift attenuation. These all-cause forecasts constrained the cause-specific forecasts at successively deeper levels of the GBD cause hierarchy using cascading mortality models, thus ensuring a robust estimate of cause-specific mortality. For non-fatal measures (eg, low back pain), incidence and prevalence were forecasted from mixed-effects models with SDI as the main covariate, and YLDs were computed from the resulting prevalence forecasts and average disability weights from GBD. Alternative future scenarios were constructed by replacing appropriate reference trajectories for risk factors with hypothetical trajectories of gradual elimination of risk factor exposure from current levels to 2050. The scenarios were constructed from various sets of risk factors: environmental risks (Safer Environment scenario), risks associated with communicable, maternal, neonatal, and nutritional diseases (CMNNs; Improved Childhood Nutrition and Vaccination scenario), risks associated with major non-communicable diseases (NCDs; Improved Behavioural and Metabolic Risks scenario), and the combined effects of these three scenarios. Using the Shared Socioeconomic Pathways climate scenarios SSP2-4.5 as reference and SSP1-1.9 as an optimistic alternative in the Safer Environment scenario, we accounted for climate change impact on health by using the most recent Intergovernmental Panel on Climate Change temperature forecasts and published trajectories of ambient air pollution for the same two scenarios. Life expectancy and healthy life expectancy were computed using standard methods. The forecasting framework includes computing the age-sex-specific future population for each location and separately for each scenario. 95% uncertainty intervals (UIs) for each individual future estimate were derived from the 2·5th and 97·5th percentiles of distributions generated from propagating 500 draws through the multistage computational pipeline. Findings: In the reference scenario forecast, global and super-regional life expectancy increased from 2022 to 2050, but improvement was at a slower pace than in the three decades preceding the COVID-19 pandemic (beginning in 2020). Gains in future life expectancy were forecasted to be greatest in super-regions with comparatively low life expectancies (such as sub-Saharan Africa) compared with super-regions with higher life expectancies (such as the high-income super-region), leading to a trend towards convergence in life expectancy across locations between now and 2050. At the super-region level, forecasted healthy life expectancy patterns were similar to those of life expectancies. Forecasts for the reference scenario found that health will improve in the coming decades, with all-cause age-standardised DALY rates decreasing in every GBD super-region. The total DALY burden measured in counts, however, will increase in every super-region, largely a function of population ageing and growth. We also forecasted that both DALY counts and age-standardised DALY rates will continue to shift from CMNNs to NCDs, with the most pronounced shifts occurring in sub-Saharan Africa (60·1% [95% UI 56·8–63·1] of DALYs were from CMNNs in 2022 compared with 35·8% [31·0–45·0] in 2050) and south Asia (31·7% [29·2–34·1] to 15·5% [13·7–17·5]). This shift is reflected in the leading global causes of DALYs, with the top four causes in 2050 being ischaemic heart disease, stroke, diabetes, and chronic obstructive pulmonary disease, compared with 2022, with ischaemic heart disease, neonatal disorders, stroke, and lower respiratory infections at the top. The global proportion of DALYs due to YLDs likewise increased from 33·8% (27·4–40·3) to 41·1% (33·9–48·1) from 2022 to 2050, demonstrating an important shift in overall disease burden towards morbidity and away from premature death. The largest shift of this kind was forecasted for sub-Saharan Africa, from 20·1% (15·6–25·3) of DALYs due to YLDs in 2022 to 35·6% (26·5–43·0) in 2050. In the assessment of alternative future scenarios, the combined effects of the scenarios (Safer Environment, Improved Childhood Nutrition and Vaccination, and Improved Behavioural and Metabolic Risks scenarios) demonstrated an important decrease in the global burden of DALYs in 2050 of 15·4% (13·5–17·5) compared with the reference scenario, with decreases across super-regions ranging from 10·4% (9·7–11·3) in the high-income super-region to 23·9% (20·7–27·3) in north Africa and the Middle East. The Safer Environment scenario had its largest decrease in sub-Saharan Africa (5·2% [3·5–6·8]), the Improved Behavioural and Metabolic Risks scenario in north Africa and the Middle East (23·2% [20·2–26·5]), and the Improved Nutrition and Vaccination scenario in sub-Saharan Africa (2·0% [–0·6 to 3·6]). Interpretation: Globally, life expectancy and age-standardised disease burden were forecasted to improve between 2022 and 2050, with the majority of the burden continuing to shift from CMNNs to NCDs. That said, continued progress on reducing the CMNN disease burden will be dependent on maintaining investment in and policy emphasis on CMNN disease prevention and treatment. Mostly due to growth and ageing of populations, the number of deaths and DALYs due to all causes combined will generally increase. By constructing alternative future scenarios wherein certain risk exposures are eliminated by 2050, we have shown that opportunities exist to substantially improve health outcomes in the future through concerted efforts to prevent exposure to well established risk factors and to expand access to key health interventions

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic

Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Different dietary protein:energy ratios for dairy goats

Dois experimentos foram conduzidos para avaliar o desempenho de cabras leiteiras alimentadas com quatro dietas isoenergéticas contendo 1,53 Mcal de energia líquida/kg MS e diferentes concentrações de proteína bruta (PB), 11,4; 16,5; 19,5 e 22,6%, que resultaram nas seguintes razões PB:energia líquida (PB/EL): 7,3; 10,8; 12,9 e 14,8; respectivamente. Os experimentos foram conduzidos com o objetivo de avaliar os efeitos das razões PB/EL sobre o consumo, a digestibilidade de matéria seca (MS) e nutrientes, a produção e a composição do leite de cabras, o metabolismo de nitrogênio, os metabólitos plasmáticos, o comportamento ingestivo e os parâmetros digestivos e metabólicos de cabras. No primeiro experimento, foram utilizadas oito cabras lactantes, distribuídas em dois quadrados latino 4 x 4, com período experimental de 21 dias – 14 dias de adaptação e sete para coleta de amostras, enquanto, no segundo, quatro cabras canuladas no rúmen foram distribuídas em um quadrado latino 4 x 4, com período experimental de 21 dias – 12 dias de adaptação e nove para coleta de amostras. Os animais foram mantidos em baias individuais adaptadas para coleta total de fezes e urina. Para as cabras lactantes foram observados maiores consumos de MS e PB nas razões mais altas de PB/EL. De maneira inversa, nos tratamentos com menor razão dos nutrientes estudados, houve maiores consumos de CNF e EE e, conseqüentemente, redução no consumo de NDT e EL. Maior digestibilidade de EE foi observada nas cabras lactantes quando usada a menor razão PB/EL. Menor digestibilidade da PB foi observada ao se adicionarem fontes nitrogenadas de alta degradabilidade ruminal como a uréia no tratamento com a menor razão PB/EL (7,3). A digestibilidade da MS apresentou diferenças significativas entre os níveis extremos das razões PB/EL e foi menor para o nível 7,3. Maior produção de leite foi observada ao se compararem as razões PB/EL de 14,8 e de 7,3 e 10,8, porém nenhuma alteração ocorreu para os componentes do leite. Maiores valores de eficiência de uso da MS consumida foram observados no tratamento com maior razão PB/EL, mas a eficiência de uso do N no leite em relação ao N consumido foi reduzida de maneira inversa. Maiores consumos de N e quantidade de N na urina e no leite e de N retido foram observados nos níveis mais altos de PB/EL. A quantidade de N excretado nas fezes e a concentração de N-uréia na urina não foram influenciados pelos tratamentos. A concentração plasmática de glicose e de proteínas totais não foi influenciada pelas razões PB/EL, enquanto a maior concentração plasmática de uréia foi observada nos níveis mais altos de PB/EL. O comportamento ingestivo das cabras e as digestibilidades aparente da MS e dos nutrientes não foram influenciados pelas razões PB/EL, em cabras canuladas no rúmen. Todavia, as digestibilidades ruminal e intestinal da PB apresentaram diferenças significativas ao se compararem as razões PB/EL, que influenciaram o consumo de nitrogênio (N em g/dia) e a excreção urinária de N (g/dia). O pH e a concentração ruminal de amônia apresentaram diferenças significativas ao se compararem as razões PB/EL. As concentrações plasmáticas de glicose e de proteínas totais não foram influenciadas pelas razões PB/EL avaliadas, mas com efeito sobre a concentração plasmática de uréia.Two trials were conducted to evaluate the effects of feeding four isoenergy diets (1.53 Mcal of net energy/kg DM) and different crude protein [CP] levels - 11.4, 16.5, 19.5, and 22.6%). The following protein:net energy ratios (CP/NE) were used: 7.3, 10.8, 12.9, and 14.8, respectively) on intake, nutrient digestibility, milk yield and composition, nitrogen metabolism, plasma metabolites, ingestive behavior and digestive and metabolic parameter, in dairy goats. In the first trial, eight lactating goats were randomly assigned to two 4 x 4 Latin squares with 21 days period (14 days for diet adaptation and seven days for sample collection). In the second trial, four ruminally cannulated goats were randomly assigned to a 4 x 4 Latin square with periods also lasting 21 days but 12 days for diet adaptation and nine days for sample collection. Animals were confined in individual stalls for total collections of feces and urine. Higher intakes of DM and CP were observed at higher CP/NE ratios while greater intakes of NFC and EE were found at lower CP/NE ratios leading to decreased TDN and NE intakes. Feeding the lowest CP/NE ratio to lactating goats resulted in higher total tract digestibility of EE. Inclusion of urea, which is rapidly degraded in the rumen, in the diet with the smallest CP/NE ratio decreased the total tract digestibility of CP in this trial. Significant differences were observed for DM digestibility across the treatments with the lowest values for goats fed diet containing a 7.3 CP/NE ratio. - x -Higher milk yield was observed comparing 14.8, 7.3, and 10.8 CP/NE ratios, but not significant effects were found for milk components. The treatment with highest CP/NE ratio also had greatest feed efficiency whereas milk N efficiency decreased. As expected, goats fed higher CP/NE ratios consumed and excreted more N in the urine and milk. It was also observed a greater N retention on these diets. No significant changes in N excreted in both urine and feces were observed among treatments. The CP/NE ratios did not affect the concentrations of plasma glucose and total protein but higher urea plasma concentration was found at higher CP/NE ratios. The CP/NE ratios did not change significantly ingestive behavior and apparent nutrient digestibilities of ruminally cannulated goats. However, significant differences were noticed for ruminal and intestinal CP digestibilities comparing the different CP/NE ratios. Increasing the dietary CP/NE ratio also increased N intake and urinary N excretion. Significant effects of CP/NE ratios on pH and ruminal ammonia concentration were detected. The CP/NE ratios did not affect the concentrations of plasma glucose and total protein, but showed significant effect on the urea plasma concentration.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Effect of dietary net energy level on performance and non esterified fatty acid fatty acid level of dairy goats under different body conditions in the transition period

O estudo foi conduzido nas dependências do Departamento de Zootecnia da Universidade Federal de Viçosa, Setor de Caprinocultura, com o objetivo de avaliar as relações entre diferentes níveis de energia em dietas, durante o período de transição, e a condição corporal de cabras leiteiras sobre o consumo de matéria seca, fibra e energia, bem como a performance produtiva no terço inicial da lactação. Utilizaram-se 48 cabras gestantes e posteriormente 45 cabras lactantes, alojadas em baias individuais. O período experimental foi de 90 dias, 30 dias antes do parto previsto até 60 dias de lactação. Os animais foram divididos em dois grupos, um com escore da condição corporal maior que 3,25 e outro com escore menor que 3,25. Durante o período pré-parto, foram oferecidas às cabras dietas isoprotéicas (13% de PB), com diferentes níveis de energia líquida (1,1; 1,4 e 1,6 Mcal de EL/kg de MS), e, durante o período pós-parto, as dietas também foram isoprotéicas (16% de PB), com dois níveis de energia líquida (1,4 e 1,6 Mcal de EL/kg de MS). As dietas foram oferecidas duas vezes ao dia, a primeira vez pela manhã e a segunda à tarde, ambas após a ordenha da manhã e da tarde, respectivamente. Os animais foram pesados por três dias consecutivos, após a ordenha da manhã a cada 15 dias, período em que foi realizada, também, a avaliação da condição corporal. Diariamente, foram realizados ajuste de consumo, duas ordenhas e coletas das sobras para posteriores análises bromatológicas. Semanalmente, foram coletadas amostras de leite e realizadas análise de densidade e de gordura, sendo feitas amostras compostas para posteriores análises laboratoriais de proteína. Durante 21 dias anteriores ao parto previsto até 21 dias após o parto, foram coletadas amostras de sangue a cada sete dias para análise de ácidos graxos não-esterificados (AGNE). Analisada individualmente durante o período de pré-parto, a condição corporal influenciou (P3,25) apresentaram menor consumo, quando comparados com os de menor condição corporal (<3,25). Ao se aumentar o nível de energia líquida das dietas, houve aumento (P<0,05) no consumo de MS e EL e redução no consumo de FDN. No período pós-parto, a interação entre condição corporal e os níveis de energia líquida influenciou (P<0,05) o consumo de FDN, sendo que as cabras com menor condição corporal apresentaram consumos de FDN diferentes para os dois níveis de energia. Os níveis de energia fornecidos durante o período pós-parto influenciaram (P<0,05) o consumo de MS, FDN e EL, sendo que o aumento na densidade energética da dieta proporcionou incremento no consumo de MS. Em relação aos níveis de AGNE, durante o período pré-parto, apenas aos 14 dias antes do parto e no dia do parto houve influência (P<0,05) dos níveis de energia líquida, sendo que as cabras que consumiram a dieta menos energética apresentaram maiores concentrações de AGNE.This experiment was conducted at the Dairy Goat Facility of the Department of Animal Science of Federal University of Viçosa, to evaluate the relations of different levels of dietary energy, in the transition period, and the body condition of dairy goats on dry matter, fiber and energy intakes, as well as on productive performance in the first three weeks of lactation. Forty-eight pregnant goats, followed by forty-five dairy goats, were kept in individual cages. The experimental period lasted 90 days, 30 days before parturition until 60 days of lactation. The animals were separated in two groups, one with body condition score higher than 3.25 and other with body condition score lower than 3.25. During the prepartum period, goats were fed isoprotein diets (13% CP), with different levels of net energy (1.1, 1.4, and 1.6 Mcal NE/kg DM), and, during the postpartum period, the diets were also isoprotein (16% CP), with two levels of net energy (1.4 and 1.6 Mcal NE/kg DM). The diets were fed twice a day, first in the morning and, after, in the afternoon, both after morning and afternoon milking, respectively. The animals were weighed for three consecutive days, after the morning milking, every 15 days, period also used to evaluate the body condition. Feed intake was daily measured, two milking were taken and samples of orts were collected for posterior chemical analyses. Samples of milk were weekly collected for analysis of density and fat, and two milk samples were collected for posterior analysis of protein. During 21 days before parturition until 21 days after parturition, blood samples were collected every seven days for analysis of non esterified fatty acids (NEFA). Dry matter (DM) and neutral detergent fiber (NDF) were affected (P<0.05) by the body condition, that was individually analyzed during the prepartum period, and the animals with body condition higher than 3.25 showed lower intake, when compared to those with body condition lower than 3.25. DM and NE intake increased (P<0.05) and NDF intake decreased as dietary net energy level increased. In the postpartum period, the interaction between body condition and net energy levels affected (P<0.05) NDF intake, and goats with lower body condition showed different NDF intakes for both energy levels. The energy levels fed during the postpartum period affected (P<0.05) DM, NDF and NE intakes. DM intake increased as dietary energy density increased. Concerning the NEFA levels, during the prepartum period, only at 14 days before parturition and at the parturition day there was positive effect (P<0.05) of net energy levels. Goats fed diets with lower energy levels showed higher NEFA levels.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorDissertação importada do Alexandri