A 1000-cow study across four European countries was undertaken to understand to what extent ruminant microbiomes can be controlled by the host animal and to identify characteristics of the host rumen microbiome axis that determine productivity and methane emissions. A core rumen microbiome, phylogenetically linked and with a preserved hierarchical structure, was identified. A 39-member subset of the core formed hubs in co-occurrence networks linking microbiome structure to host genetics and phenotype (methane emissions, rumen and blood metabolites, and milk production efficiency). These phenotypes can be predicted from the core microbiome using machine learning algorithms. The heritable core microbes, therefore, present primary targets for rumen manipulation toward sustainable and environmentally friendly agriculture.

The objective of this study was to identify the risk factors associated with 3 presentations of hock lesions (hair loss, ulceration, and swelling) in freestall-housed lactating cattle. By independent identification and scoring of, and analysis of the factors associated with, hair loss, ulceration, and swelling, the aim was to identify whether risk factors were common to all 3, or differed among the presentations. A cross-sectional study was conducted on 76 herds in the UK during the winter housing period of 2007 to 2008, with a total of 3,691 cows examined for hock lesions. A randomly selected sample of approximately 50 cows in each herd were scored for body condition, lameness, cleanliness, rising behavior, and lesions at the hocks. For all cows, hair loss, ulceration, and swelling were scored separately on 4-point scales, with both left and right hocks scored. Based on a review of the literature, potential risk factors were identified and measured, collected from milk-recording data, or obtained through interviews with the farmers. Risk factors associated with hocks lesions in cattle were examined using data from the 2,982 cows housed in the 63 freestall-housed herds visited. Risk factors for each of the 3 lesion presentations were considered separately in multilevel logistic regression models, with moderate or severe hair loss, any degree of ulceration, and moderate or severe swelling as the outcome variables. Thirty risk factors were identified, none of which were common to all 3 lesion presentations. Five risk factors (locomotion score, number of days of winter housing, mean milk yield, freestall base material, and herd size) were common to both hair loss and ulceration. The stall bedding material was a common risk factor for both hair loss and swelling. A further 8, 5, and 11 risk factors were unique to hair loss, ulceration, and swelling, respectively. The existence of several differential risk factors between the 2 lesion presentations suggests that ulceration may not always be a direct extension of hair loss, as has been implied in previous scoring systems. Of the 12 risk factors associated with swelling, only 1 was common to another lesion presentation, which suggests that swelling may have a different etiology than hair loss and ulceration. The variables associated with the lesions indicate the importance of factors that affect the lying and rising behavior of the animal, including freestall structure and design, and the lying surface.

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Methane (CH 4 ) emissions by dairy cows vary with feed intake and diet composition. Even when fed on the same diet at the same intake, however, variation between cows in CH 4 emissions can be substantial. The extent of variation in CH 4 emissions among dairy cows on commercial farms is unknown, but developments in methodology now permit quantification of CH 4 emissions by individual cows under commercial conditions. The aim of this research was to assess variation among cows in emissions of eructed CH 4 during milking on commercial dairy farms. Enteric CH 4 emissions from 1964 individual cows across 21 farms were measured for at least 7 days/cow using CH 4 analysers at robotic milking stations. Cows were predominantly of Holstein Friesian breed and remained on the same feeding systems during sampling. Effects of explanatory variables on average CH 4 emissions per individual cow were assessed by fitting a linear mixed model. Significant effects were found for week of lactation, daily milk yield and farm. The effect of milk yield on CH 4 emissions varied among farms. Considerable variation in CH 4 emissions was observed among cows after adjusting for fixed and random effects, with the CV ranging from 22% to 67% within farms. This study confirms that enteric CH 4 emissions vary among cows on commercial farms, suggesting that there is considerable scope for selecting individual cows and management systems with reduced emissions.

The objectives of this paper were to characterise lesions found at the hock and to establish their prevalence across a large sample of dairy cows in the UK. In addition, the study aimed to examine farmers' perceptions of these lesions. Seventy-seven farms were visited; both hocks on a random sample of approximately 50 cows were scored on a categorical scale for hair loss, ulceration and swelling. In addition, the size and location of lesions were marked on a hock map. A questionnaire designed to explore attitudes towards lesions was conducted with the owner. Hair loss and ulceration were seen at five locations. Hair loss was identified on 5,619 of 6,896 hocks (mild: 43.7 per cent; moderate: 25.1 per cent; severe: 12.6 per cent) and 1,137 of 6,896 hocks had areas of ulceration (mild: 8.6 per cent; moderate: 5.8 per cent; severe: 2.1 per cent). The majority of lesions were small; however, a small proportion had extensive areas of hair loss (maximum size 113.3 cm2) and ulceration (maximum size 95.5 cm2). Moderate swelling was recorded on 20 per cent of hocks, and 2.0 per cent had severe swelling. Interview results suggested that more than 90 per cent of participants were aware of hock lesions and a third had sought treatment for them; most felt that lesions had at least some impact on productivity and welfare.