Cattle and other ruminants produce large quantities of methane (~110 million metric tonnes per annum), which is a potent greenhouse gas affecting global climate change. Methane (CH4) is a natural by-product of gastro-enteric microbial fermentation of feedstuffs in the rumen and contributes to 6% of total CH4 emissions from anthropogenic-related sources. The extent to which the host genome and rumen microbiome influence CH4 emission is not yet well known. This study confirms individual variation in CH4 production was influenced by individual host (cow) genotype, as well as the host’s rumen microbiome composition. Abundance of a small proportion of bacteria and archaea taxa were influenced to a limited extent by the host’s genotype and certain taxa were associated with CH4 emissions. However, the cumulative effect of all bacteria and archaea on CH4 production was 13%, the host genetics (heritability) was 21% and the two are largely independent. This study demonstrates variation in CH4 emission is likely not modulated through cow genetic effects on the rumen microbiome. Therefore, the rumen microbiome and cow genome could be targeted independently, by breeding low methane-emitting cows and in parallel, by investigating possible strategies that target changes in the rumen microbiome to reduce CH4 emissions in the cattle industry.

SummaryA reciprocal cross-fostering model with an obese typical Chinese piglet breed and a lean Western breed was used to identify genetic and maternal effects on the acquisition and development gut bacteria from birth until after weaning. Pyrosequencing of 16S rRNA genes results revealed an age-and diet-dependent bacterial succession process in piglets. During the first 3 days after birth, the bacterial community was relatively simple and dominated by Firmicutes with 79% and 65% relative abundance for Meishan and Yorkshire piglets, respectively. During the suckling period until day 14, the piglet breed and the nursing mother lead to increasing differentiation of the fecal bacterial community, with specific bacteria taxa associated with breed, and others with the nursing sow most likely due to its milk composition. Although the effect of nursing mother and the breed were evident through the suckling period, the introduction of solid feed and subsequent weaning were the major events occurring that dominated succession of the gut microbiota in the early life of piglets. This piglet crossfostering model is a useful tool for studying the effects of diet, host genetics and the environment on the development and acquisition of the gut microbiota and over longer studies the subsequent impact on growth, health and performance of pigs.

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Some studies reported a significant association between polycystic ovary syndrome (PCOS) and risk of cardiovascular disease (CVD). However, the results are controversial. A systematic search was conducted in the PubMed, Science Direct, EMBASE, and Cochrane Library databases. Five case-control studies and 5 cohort studies were selected, involving a total of 104392 subjects in this meta-analysis. PCOS was significantly associated with the increased risk of CVD (OR = 1.30; 95% CI 1.09 – 1.56; P = 0.004). In the subgroup analysis of study design, both case-control studies and prospective cohort studies showed significant results (OR = 1.79; 95% CI 1.16 – 2.77; P = 0.009; OR = 1.20; 95% CI 1.06 – 1.37; P = 0.005), while retrospective cohort studies did not show positive result (OR = 0.91; 95% CI 0.60 – 1.40; P = 0.68). In a further stratified analysis by type of CVD, a significant association was found between PCOS and coronary heart disease (CHD) (OR = 1.44; 95% CI 1.13 – 1.84; P = 0.004). However, no significant association was observed between PCOS and myocardial infarction (MI) (OR = 1.01; 95% CI 0.68 – 1.51; P = 0.95). In conclusion, this meta-analysis suggested that PCOS is significantly associated with increased CHD risk.