Rapid changes in key ruminal microbial populations during the induction of and recovery from diet-induced milk fat depression in dairy cows.

The ruminant provides a powerful model for understanding the temporal dynamics of gastrointestinal microbial communities. Diet-induced milk fat depression (MFD) in the dairy cow is caused by rumen-derived bioactive fatty acids, and is commonly attributed to the changes in the microbial population. The aim of the present study was to determine the changes occurring in nine ruminal bacterial taxa with well-characterised functions, and abundance of total fungi, ciliate protozoa and bacteria during the induction of and recovery from MFD. Interactions between treatment and time were observed for ten of the twelve populations. The total number of both fungi and ciliate protozoa decreased rapidly (days 4 and 8, respectively) by more than 90% during the induction period and increased during the recovery period. The abundance of Streptococcus bovis (amylolytic) peaked at 350% of control levels on day 4 of induction and rapidly decreased during the recovery period. The abundance of Prevotella bryantii (amylolytic) decreased by 66% from day 8 to 20 of the induction period and increased to the control levels on day 12 of the recovery period. The abundance of Megasphaera elsdenii and Selenomonas ruminantium (lactate-utilising bacteria) increased progressively until day 12 of induction (>170%) and decreased during the recovery period. The abundance of Fibrobacter succinogenes (fibrolytic) decreased by 97% on day 4 of induction and increased progressively to an equal extent during the recovery period, although smaller changes were observed for other fibrolytic bacteria. The abundance of the Butyrivibrio fibrisolvens/Pseudobutyrivibrio group decreased progressively during the induction period and increased during the recovery period, whereas the abundance of Butyrivibrio hungatei was not affected by treatment. Responsive taxa were modified rapidly, with the majority of changes occurring within 8 d and their time course was similar to the time course of the induction of MFD, demonstrating a strong correlation between changes in ruminal microbial populations and MFD.

Age reporting among white Americans aged 85+: results of a record linkage study.

This study investigates age reporting on the death certificates of older white Americans. We link a sample of death certificates for native-born whites aged 85+ in 1985 to Social Security Administration records and to records of the U.S. censuses of 1900, 1910, and 1920. When ages in these sources are compared, inconsistencies are found to be minimal, even beyond age 95. Results show little distortion and no systematic biases in the reported age distribution of deaths. To explore the effect of age misreporting on old-age mortality, we estimate "corrected" age-specific death rates by the extinct-generation method for the U.S. white cohort born in 1885. With few exceptions, corrected and uncorrected rates in single years differ by less than 3% and are not systematically biased. When we compare corrected rates with those for the same birth cohort in France, Japan, and Sweden, we find that white American mortality at older ages is exceptionally low.