Influence of environmental factors and parity on milk yield dynamics in barn-housed dairy cattle.

We investigated the effects of environmental factors on average daily milk yield and day-to-day variation in milk yield of barn-housed Scottish dairy cows milked with an automated milking system. An incomplete Wood gamma function was fitted to derive parameters describing the milk yield curve including initial milk yield, inclining slope, declining slope, peak milk yield, time of peak, persistency (time in which the cow maintains high yield beyond the peak), and predicted total lactation milk yield (PTLMY). Lactation curves were fitted using generalized linear mixed models incorporating the above parameters (initial milk yield, inclining and declining slopes) and both the indoor and outdoor weather variables (temperature, humidity, and temperature-humidity index) as fixed effects. There was a higher initial milk yield and PTLMY in multiparous cows, but the incline slope parameter and persistency were greatest in primiparous cows. Primiparous cows took 54 d longer to attain a peak yield (mean ± standard error) of 34.25 ± 0.58 kg than multiparous (47.3 ± 0.45 kg); however, multiparous cows yielded 2,209 kg more PTLMY. The best models incorporated 2-d lagged minimum temperature. However, effect of temperature was minimal (primiparous decreased milk yield by 0.006 kg/d and multiparous by 0.001 kg/d for each degree increase in temperature). Both primiparous and multiparous cows significantly decreased in day-to-day variation in milk yield as temperature increased (primiparous cows decreased 0.05 kg/d for every degree increase in 2-d lagged minimum temperature indoors, which was greater than the effect in multiparous cows of 0.008 kg/d). Though the model estimates for both indoor and outdoor were different, a similar pattern of the average daily milk yield and day-to-day variation in milk yield and milk yield's dependence on environmental factors was observed for both primiparous and multiparous cows. In Scotland, primiparous cows were more greatly affected by the 2-d lagged minimum temperature compared with multiparous cows. After peak lactation had been reached, primiparous and multiparous cows decreased milk yield as indoor and outdoor minimum temperature increased.

Regulation of intestinal growth in response to variations in energy supply and demand.

The growth of the intestine requires energy, which is known to be met by catabolism of ingested nutrients. Paradoxically, during whole body energy deficit including calorie restriction, the intestine grows in size. To understand how and why this happens, we reviewed data from several animal models of energetic challenge. These were bariatric surgery, cold exposure, lactation, dietary whey protein intake and calorie restriction. Notably, these challenges all reduced the adipose tissue mass, altered hypothalamic neuropeptide expression and increased intestinal size. Based on these data, we propose that the loss of energy in the adipose tissue promotes the growth of the intestine via a signalling mechanism involving the hypothalamus. We discuss possible candidates in this pathway including data showing a correlative change in intestinal (ileal) expression of the cyclin D1 gene with adipose tissue mass, adipose derived-hormone leptin and hypothalamic expression of leptin receptor and the pro-opiomelanocortin gene. The ability of the intestine to grow in size during depletion of energy stores provides a mechanism to maximize assimilation of ingested energy and in turn sustain critical functions of tissues important for survival.

Effect of vitamin D3 supplementation on blood pressure in adults: An updated meta-analysis.

BACKGROUND AND AIMS: Previous randomized clinical trials (RCTs) of the effects of vitamin D3 supplementation (VD3S) on blood pressure have generated inconsistent results. We evaluated the effect of VD3S on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in a meta-analysis. DATA SYNTHESIS: Literature searches of PubMed, Scopus, Ovid, and Google scholar for publications in English were conducted up to April 2015. RCTs that assessed the effect of VD3S on SBP and DBP were selected. CONCLUSIONS: A total of 30 RCTs with 41 arms including 4744 participants were included. The mean duration of the studies was 5.6 ± 4.0 months, and doses of VD3S varied between 200 and 12,000 IU/day. VD3S had no effect on SBP (-0.68 mmHg, 95%CI: -2.19 to 0.84), and DBP (-0.57 mmHg, 95%CI: -1.36 to 0.22). Subgroup analysis revealed that daily vitamin D3 therapy at a dose of >800 IU/day for <6 months in subjects ≥50 years old reduced both SBP and DBP (p < 0.001). In addition, VD3S showed hypotensive effects in healthy subjects and hypertensive patients, but a hypertensive effect in overweight and obese subjects. However, after excluding overweight and obese subjects, VD3S significantly reduced SBP and DBP. VD3S in combination with calcium supplementation significantly elevated SBP (3.64 mmHg, 95%CI: 3.15-4.13) and DBP (1.71 mmHg, 95%CI: 1.25-2.18). No evidence of publication bias was found. The effects of VD3S on blood pressure depend on dose of supplementation, treatment regimens, trial duration, and population subgroup. Supplementation may be beneficial at daily doses >800 IU/day for <6 months in subjects ≥50 years old.

Effect of vitamin E supplementation on serum C-reactive protein level: a meta-analysis of randomized controlled trials.

C-reactive protein (CRP), a marker of chronic inflammation, has a major role in the etiology of chronic disease. Vitamin E may have anti-inflammatory effects. However, there is no consensus on the effects of vitamin E supplementation on CRP levels in clinical trials. The aim of this study was to systematically review randomized controlled trials (RCTs) that report on the effects of vitamin E supplementation (α- and γ-tocopherols) on CRP levels. A systematic search of RCTs was conducted on Medline and EMBASE through PubMed, Scopus, Ovid and Science Direct, and completed by a manual review of the literature up to May 2014. Pooled effects were estimated by using random-effects models and heterogeneity was assessed by Cochran's Q and I(2) tests. Subgroup analyses and meta-regression analyses were also performed according to intervention duration, dose of supplementation and baseline level of CRP. Of 4734 potentially relevant studies, only 12 trials met the inclusion criteria with 246 participants in the intervention arms and 249 participants in control arms. Pooled analysis showed a significant reduction in CRP levels of 0.62 mg/l (95% confidence interval = -0.92, -0.31; P < 0.001) in vitamin E-treated individuals, with the evidence of heterogeneity across studies. This significant effect was maintained in all subgroups, although the univariate meta-regression analysis showed that the vitamin E supplementation dose, baseline level of CRP and duration of intervention were not the sources of the observed heterogeneity. The results of this meta-analysis suggest that supplementation with vitamin E in the form of either α-tocopherol or γ-tocopherol would reduce serum CRP levels.

α-Tocopherol supplementation reduces biomarkers of oxidative stress in children with Down syndrome: a randomized controlled trial.

BACKGROUND: Down syndrome (DS) is the most common human chromosomal abnormality. It is characterized by mental retardation and several metabolic disturbances, including elevated oxidative stress, which may be causally linked. Treatment with dietary antioxidants has been suggested as a potential method to alleviate the oxidative damage and retardation of DS patients, but prior supplementation work has been equivocal. AIM: To evaluate the effects of supplementation with antioxidants α-tocopherol and α-lipoic acid (ALA) on oxidative stress biomarkers in DS children. METHODS: Ninety-three DS children aged 7-15 years from both sexes were randomly allocated to three groups: α-tocopherol (400 IU/day), ALA (100 mg/day) and placebo. The intervention period was 4 months. A healthy control group consisted 26 non-DS siblings. Serum thiobarbituric acid reactive substances (TBARS) and urinary 8-hydroxy-2'-deoxyguanosine (8OHdG) were used as biomarkers of oxidative stress. RESULTS: DS children had greater levels of baseline oxidative stress than their siblings. Moreover, males had greater levels of 8OHdG than females (P<0.001) but there was no significant association between age and biomarkers of oxidative stress. Serum levels of TBARS did not change significantly over time, or relative to placebo. Although urinary 8OHdG concentrations decreased significantly in both α-tocopherol and ALA, groups compared with the baseline levels (P<0.001), mean final levels of urinary 8OHdG concentrations differed significantly only between α-tocopherol and placebo groups (P<0.01). CONCLUSIONS: α-Tocopherol supplementation of the diets of DS children may attenuate oxidative stress at the DNA level.

Photoperiodic effects on body mass, energy balance and hypothalamic gene expression in the bank vole.

We examined the effect of increasing photoperiod, at a constant low temperature, on the body mass and energy budget of the bank vole Clethrionomys glareolus. Simultaneously, we determined the hypothalamic gene expression of neuropeptides and receptors known to be involved in short-term energy balance. Despite an increase in body mass (approximately 10% of initial mass), we found no significant changes in any energetic parameters (food intake, energy assimilation rate, resting metabolic rate and total daily energy expenditure by doubly-labelled water). Apparent energy assimilation efficiency was higher in voles exposed to long-days (LD) compared to short-days (SD). Surprisingly, gene expression of corticotrophin releasing factor (CRF; in the paraventricular nucleus), and the melanocortin-3 receptor (in the arcuate nucleus), both known to be involved in appetite suppression and elevation of energy expenditure in short-term energy balance, were higher in voles kept in LD compared to SD. CRF expression was also elevated in females compared to males. These paradoxical data suggest an alternative mechanism for the control of seasonal body mass changes compared to short-term body mass changes, and between male and female voles. Furthermore, they highlight the need for studies to perform simultaneous measurements at both the molecular and whole animal levels.

Hypothalamic neuropeptide mechanisms for regulating energy balance: from rodent models to human obesity.

In small rodents there is compelling evidence of a lipostatic system of body mass regulation in which peripheral signals of energy storage are decoded in the hypothalamus. The ability of small mammals to defend an appropriate mass against imposed energy imbalance has implicated hypothalamic neuroendocrine systems in body mass regulation. The effect of the neuropeptide systems involved in this regulation is primarily compensatory. However, small mammals can also effect changes in the level of body mass that they will defend, as exemplified by seasonal species. Regulatory control over fat mass may be relatively loose in humans; the sizes of long-term storage depots may not themselves be regulated, but rather may be a consequence of temporal variations in the matching of supply and demand. Whether food intake is regulated to match energy demand, or to match demand and to regulate storage, it is clear that physiological defects or genetic variation in hypothalamic and peripheral feedback systems will have profound implications for fat storage. Study of mechanisms implicated in energy homeostasis in laboratory rodents is likely to continue to identify targets for pharmacological manipulation in the management of human obesity.