The influence of somatic growth and genetic selection on the whole blood oxygen equilibrium curve (OEC) was measured under standard conditions in double-muscled and dairy calves during their first 3 mo of life. Crossbreed animals were also investigated. Hemoglobin, 2,3-diphosphoglycerate (DPG), Cl, and Pi concentrations were also measured. The percentage of fetal hemoglobin (HbF) was determined. The influence of exogenous Cl, Pi, and pH on the OEC was also assessed. The PO2 at 50% hemoglobin saturation (P50) increased during somatic growth, probably because of the increase in DPG recorded in double-muscled neonates and to the progressive disappearance of HbF in both breeds. The oxygen exchange fraction (OEF%) was used to assess the combined influence of the OEC shift and OEC shape changes on blood oxygen desaturation under standard conditions, when the PO2 decreases within a physiological range. The OEF% showed an increase during the first month, then a stabilization. The effects of Cl, Pi, and pH in Friesian calves were similar as in adult cattle. Double-muscled neonates had a lower P50, OEF% values, and DPG concentrations and higher hemoglobin and Cl concentrations than Friesian neonates. The Pi concentration and the percentage of HbF were similar in both breeds. The pH and the Cl concentration had significantly less effect on the OEC in double-muscled than in Friesian calves. Crossbreed animals exhibited intermediate parameter values, between those recorded for double-muscled and Friesian calves. All differences between breeds progressively disappeared during the first month. These data show that blood function changes markedly in calves during the first month of life and that genetic selection can alter blood function.
Climate change has the potential to impair livestock health, with consequences for animal welfare, productivity, greenhouse gas emissions, and human livelihoods and health. Modelling has an important role in assessing the impacts of climate change on livestock systems and the efficacy of potential adaptation strategies, to support decision making for more efficient, resilient and sustainable production. However, a coherent set of challenges and research priorities for modelling livestock health and pathogens under climate change has not previously been available. To identify such challenges and priorities, researchers from across Europe were engaged in a horizon-scanning study, involving workshop and questionnaire based exercises and focussed literature reviews. Eighteen key challenges were identified and grouped into six categories based on subject-specific and capacity building requirements. Across a number of challenges, the need for inventories relating model types to different applications (e.g. the pathogen species, region, scale of focus and purpose to which they can be applied) was identified, in order to identify gaps in capability in relation to the impacts of climate change on animal health. The need for collaboration and learning across disciplines was highlighted in several challenges, e.g. to better understand and model complex ecological interactions between pathogens, vectors, wildlife hosts and livestock in the context of climate change. Collaboration between socio-economic and biophysical disciplines was seen as important for better engagement with stakeholders and for improved modelling of the costs and benefits of poor livestock health. The need for more comprehensive validation of empirical relationships, for harmonising terminology and measurements, and for building capacity for under-researched nations, systems and health problems indicated the importance of joined up approaches across nations. The challenges and priorities identified can help focus the development of modelling capacity and future research structures in this vital field. Well-funded networks capable of managing the long-term development of shared resources are required in order to create a cohesive modelling community equipped to tackle the complex challenges of climate change.
Subacute ruminal acidosis (SARA) has been considered a major pathology in high producing dairy herds for years. These findings were corroborated by several studies in Europe. However, different feeding practices and herds’ production levels are found in Southern Belgium. This study aimed to ascertain whether dairy cows of several herds from the south of Belgium (Wallonia) with a suspicion of SARA really did present too low ruminal pH values. Twenty-four herds were visited and 172 cows were sampled using an oropharyngeal device to collect ruminal fluid, i.e. Geishauser probe. On the samples, three tests were performed: pH measurement, methylene blue reduction test and microscopic evaluation of protozoa vitality. Based on these analyses, no cows demonstrated pH values lower than 5.5 and, only ten cows could be considered at risk for SARA. By contrast, in eightteen cows, pH values higher than 7.0 were measured and ruminal inactivity was suspected. In this study, ruminal alkalosis appeared to be more frequently observed than SARA.
More dairy farms (up to more than one in four in some countries) are equipped with automatic milking systems (AMS) worldwide. Because of the positive impacts of grazing, e.g., on animal welfare or on production costs, numerous researchers have published papers on the combination of AMS with grazing. However, pasture-based AMS usually causes a reduction in milking frequency (MF) compared to indoors systems. The objectives of this meta-analysis were to review publications on the impacts of pasture-based AMS on MF and mitigation strategies. First, data from 43 selected studies were gathered in a dataset including 14 parameters, and on which a Principal Component Analysis (PCA) was performed, leading to the description of four clusters summarizing different management practices. Multiple pairwise comparisons were performed to determine the relationship between the highlighted parameters of MF on milk yield (MY). From these different analyses, the relationship between MF and MY was confirmed, the systems, i.e., Clusters 1 and 2, that experienced the lowest MF also demonstrated the lowest MY/cow per day. In these clusters, grazed grass was an essential component of the cow’s diet and low feeding costs compensated MY reduction. The management options described in Clusters 3 and 4 allowed maintenance of MF and MY by complementing the cows’ diets with concentrates or partial mixed ration supplied at the AMS feeding bin or provided at barn. The chosen management options were closely linked to the geographical origin of the papers indicating that other factors (e.g., climatic conditions or available grasslands) could be decisional key points for AMS management strategies.
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