Ian J. Lean

Bio: Ian J. Lean is an academic researcher from University of Sydney. The author has contributed to research in topics: Dairy cattle & Lactation. The author has an hindex of 39, co-authored 110 publications receiving 6667 citations. Previous affiliations of Ian J. Lean include University of California, Davis & University of California, Berkeley.

Milk fever in dairy cows: A review of pathophysiology and control principles

Abstract: The periparturient or transition period of 4 weeks before and 4 weeks after calving is characterised by a greatly increased risk of disease Hypocalcaemia around calving is a risk factor for many of these diseases and is an indirect risk factor for increased culling The incidence of clinical hypocalcaemia (milk fever) in the field generally ranges from 0-10%, but may exceed 25% of cows calving In research trials conducted on milk fever the incidence has approached 80% of cows calving Homeostasis of calcium (Ca) is regulated by calcitonin, parathyroid hormone and 1,25(OH)(2) vitamin D(3) Age increases the risk of milk fever by approximately 9% per lactation Control of milk fever has revolved around stimulation of homeostatic mechanisms through feeding a pre-calving diet low in Ca More recently, the role of the dietary cation anion difference (DCAD) in the prevention of Ca disorders has been examined, both by field research and meta-analysis The most appropriate form of the DCAD equation has been contentious, but recent meta-analyses have shown that the equation (Na(+)+K(+))-(Cl(-)+S(2-)) is most effective for predicting milk fever risk Decreased risk of milk fever is linear with DCAD, whereas the effect of DCAD on urinary pH is curvilinear A pivotal role of providing dietary magnesium (Mg) before calving has been confirmed by meta-analysis, and a quadratic effect of Ca on milk fever risk was found with a peak occurring with dietary levels of 11-13% of dry matter Risks of milk fever increase with increased dietary phosphorus (P) fed pre-calving and with increasing days of exposure to a pre-calving diet Meta-analysis has revealed that the important roles of dietary Ca, Mg and P, as well as the duration of exposure to the pre-calving diet in milk fever control strategies are independent of DCAD Studies on the effect of exposure to well designed pre-calving diets have shown that substantial improvements in production, reproduction and animal health can be made but further examination of the influence of the period of exposure to different diets is warranted

Tackling climate change through livestock : a global assessment of emissions and mitigation opportunities

Abstract: As renewed international efforts are needed to curb greenhouse gas emissions, the livestock sector can contribute its part. An important emitter of greenhouse gas, it also has the potential to significantly reduce its emissions. This report provides a unique global assessment of the magnitude, the sources and pathways of emissions from different livestock production systems and supply chains. Relying on life cycle assessment, statistical analysis and scenario building, it also provides estimates of the sector’s mitigation potential and identifies concrete options to reduce emissions. The report is a useful resource for stakeholders from livestock producers to policy-makers, researchers and civil society representatives, which also intends to inform the public debate on the role of livestock supply chains in climate change and possible solution.

Nutrient requirements of dairy cattle

Abstract: Nutrient requirements of dairy cattle , Nutrient requirements of dairy cattle , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی