A group of patients with damage to the ventral part of the frontal lobes was severely impaired relative to a group of patients without damage in this area (the non-ventral group) in the reversal and in the extinction of simple visual discrimination tests. In these tests they continued to make responses to a previously rewarded stimulus. Patients often reported verbally that the contingencies had changed, but were unable to alter their behaviour appropriately. These impairments occurred independently of IQ or verbal memory impairments. The perseverative touching of a previously rewarded stimulus is consistent with work with non-human primates showing impaired reversal and extinction after orbitofrontal lesions. Performance on these reversal and extinction tests was highly correlated with scores obtained on a behaviour questionnaire, which reflected the degree of disinhibited and socially inappropriate behaviour exhibited by patients. It is suggested that a difficulty in modifying responses, especially when followed by negative consequences, as manifested in these simple laboratory tests, may contribute to the inappropriate behaviour shown in daily life by patients with frontal lobe damage.

This review examines the role of nutritional strategies to improve lifetime performance in ruminants. Strategies to increase ruminants' productive longevity by means of nutritional interventions provide the opportunity not only to increase their lifetime performances and their welfare, but also to decrease their environmental impact. This paper will also address how such nutritional interventions can increase herd efficiency and farm profitability. The key competencies reviewed in this article are redox balance, skeletal development and health, nutrient utilization and sustainability, which includes rearing ruminants without antibiotics and methane mitigation. While the relationships between these areas are extremely complex, a multidisciplinary approach is needed to develop nutritional strategies that would allow ruminants to become more resilient to the environmental and physiological challenges that they will have to endure during their productive career. As the demand of ruminant products from the rapidly growing human world population is ever-increasing, the aim of this review is to present animal and veterinary scientists as well as nutritionists a multidisciplinary approach towards a sustainable ruminant production, while improving their nutrient utilization, health and welfare, and mitigation of their carbon footprint at the same time.

The study of vitamin D in cattle has often focussed on its role in calcium and mineral metabolism. However, there is evidence of a wider role for vitamin D in bone and energy metabolism. Two studies were conducted to explore relationships between calcidiol supplementation, blood minerals and metabolites in mid-lactation dairy cows. In Experiment 1, a dose-response study was conducted in which 25 mid-lactation cows were fed one of five supplementary calcidiol doses (0, 0.5, 1, 2 or 4 mg calcidiol/day) for 30 days, with blood samples taken every 10 days. Increasing calcidiol dose increased plasma calcidiol (P=0.001), 24,25-(OH)2-D3 (P=0.001) and serum phosphate (P=0.003) in a curvilinear manner, increased and then decreased plasma 25-OH-D2 (P=0.004) and linearly increased 3-epi 25-OH-D3 (P=0.001) and milk calcidiol concentrations (P=0.001). Calcidiol supplementation did not affect milk yield or composition, bodyweight or condition score. In Experiment 2, relationships between blood calcidiol and mineral and metabolite concentrations over time were explored using time-series analysis. Ten mid-lactation cows were fed either 0 or 0.5 mg calcidiol/day for 27 days, with blood samples taken every 3 days. Feeding calcidiol increased plasma calcidiol (P=0.001), 24,25-OH-D3 (P=0.038), and insulin (P=0.046), but decreased 25-OH-D2 (P=0.008) concentrations. Positive associations were identified between blood calcidiol and concentrations of other metabolites, including cholecalciferol, calcium, osteocalcin, glucose, insulin, non-esterified fatty acids, β-hydroxybutyrate, cholesterol, magnesium, phosphorus and total protein at varying lags (±0, 3 or 6 days), while negative relationships were identified between calcidiol and 24,25-(OH)2-D3, and phosphorus 3 days later. Importantly, strong positive associations between calcidiol and indicators of energy metabolism were identified. Overall, these experiments provide support for a positive effect of calcidiol treatment on dairy cow metabolism.

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