Browsing by Subject "Physical activity"

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Effect of Omega-3 fatty acids and physical exercise on egg quality, bone characteristics and physiological parameters in laying hens
(2013) Jahja, Ardita; Grashorn, Michael
It is well proven that eggs enriched with omega-3 fatty (n-3) acids have additional health benefits in humans. Various feeding stuffs may be used for enriching eggs with n-3 PUFA. Besides nutrition physical exercise may play a role in this context. Physical exercise influences both the metabolism of fatty acids and the mechanisms of bone formation. Bone breakage is a serious welfare problem of laying hens. Broken bones were found in about 30% of hens before slaughter and the proportion reached 90% at the end of the processing line. Beneficial effects of n-3 fatty acids have been reported on bone strength in Japanese quail and growing chickens. Thus, the objectives of the present study were to elucidate the relationships between sources of dietary fatty acids and physical exercise in laying hens on performance, egg quality, bone characteristics and some physiological criteria of lipid metabolism. In total 36 brown laying hens were used and 12 hens each were fed with three experimental diets differing only in the fat source: Palm oil (PO), Soybean oil (SO), Linseed oil (LO), corresponding to a low content of poly unsaturated fatty acids (PUFA) ? PO, high content of omega-6 (n-6) fatty acids ? SO, and high content of n-3 fatty acids ? LO. Half of hens of each dietary group (6 birds) were exposed to exercise by walking on a treadmill (EG), whereas, the remaining 6 hens served as a control (CG). EG birds were exposed to a running treadmill every day for the whole experimental period (4 wk). On the first day the birds walked 5 min with the speed of 0.5 miles/h. Then duration of walking and speed was increased progressively until day eleven. Thereafter, until the end of the experiment hens walked 25 min/day. On the first day the distance walked was 67 m and increased to 469 m/day on day eleven. The experimental design was: 3 diets x 2 activities x 6 birds = 36 hens. At the end of the experiment eggs were collected to determine yolk fatty acids profiles and hens were slaughtered to collect blood indicators for lipid metabolism, tibia bones to determine bone characteristics and hearts and livers to calculate relative weights. Diets significantly influenced egg weight, yolk proportion and fatty acids profiles. The highest egg weight was observed for SO and the highest yolk proportion for LO. Contents of SAT and MUFA were significantly higher in eggs of group PO, whereas, LO and SO showed a higher content of PUFA. Eggs of treatments SO and LO had the highest proportions of linoleic acid and linolenic acid, respectively. N-6 and n-3 contents in PO and in SO eggs were eight times higher than for LO (P<0.05). Exercise of birds did not affect egg weight, yolk proportion or fatty acids profiles indicating a dominating effect of dietary fat source. The interaction exercise x diet was significant for yolk proportion only. There was no significant effect of diet or physical exercise on bone characteristics determined by computer tomography, but, there was a consistent trend of higher level of total area and corticalis area in the LO group as compared to PO and SO groups. Total density and cortical density showed the opposite tendency. Significant diet x exercise interactions were observed for total area, corticalis area and corticalis density. Running on the treadmill resulted in lower total area and corticalis area for diets LO and PO, whereas, higher values were observed for birds with exercise fed on diet SO. In contrast, for corticalis density lower values were observed for birds without exercise fed on diets LO and PO. Further characteristics of tibia were not significantly affected by main factors or their interaction, but tibia of birds fed on diet PO showed the highest ash, Ca and P contents (% dry matter). Diet PO resulted in lower body weight, increased relative liver weight and serum cholesterol level. Hens fed with diet SO showed the highest serum ALAT level indicating an accelerated lipid metabolism. There were no significant effects of exercise on other characteristics. Interactions between dietary fat and exercise revealed that exercise can compensate negative side-effects of an increased metabolic activity for diets SO and LO, whereas, the unfavourable effects of a diet with a low content of linoleic acid (PO) cannot be removed. In summary, fatty acids profile of egg yolk has been modified by diets as expected. Physical exercise, in contrast did not show any influence on yolk fatty acid profiles. Higher levels of n-3 fatty acids in free range eggs reported in earlier studies are obviously not caused by higher physical exercise. The effect of physical exercise and diet on bone stability is not caused by the individual factors but by their interactions. While physical exercise in the LO and PO diet reduced bone area and increased bone density, the opposite effect was observed for SO diet. Since lower bone density was compensated by larger bone area the treatments did not affect bone breaking strength.
Metabolic chamber studies on energy- and macronutrient metabolism : impact of meal skipping and energy flux
(2018) Nas, Alessa; Bosy-Westphal, Anja
The classical concept of body weight regulation attributes the development of obesity to a chronically positive energy balance. There is, however, evidence indicating that beyond this basic concept, the effectiveness of body weight regulation is affected by the circadian regulation of metabolism and the level of energy flux (EF, level of energy balance). Meal skipping affects circadian regulation and might therefore also affect the regulation of body weight. In addition, an asymmetric regulation of body weight is hypothesized with improved effectiveness when EF is high (active lifestyle) and less effectiveness at a low EF (sedentary lifestyle). Metabolic chambers offer the opportunity to acquire short-term parameters of energy and macronutrient balance that precede long-term weight gain and therefore, can help to understand the impact of nutrition and physical activity interventions on body weight regulation. This thesis presents the implementation of a metabolic chamber system (Chapter II) and investigates the acute impact of meal skipping (Chapter III) and energy flux (Chapter IV) on energy and macronutrient metabolism by performing two well-controlled, cross-over intervention studies using metabolic chambers. The implementation of the metabolic chambers revealed, that thorough considerations must be made in terms of the metabolic chamber environment (room ventilation and position of analyzer unit), the additional devices (e.g. air conditioner) used as well as the study protocol, in order to obtain good data quality. The study on meal skipping includes 17 healthy participants who underwent 3 isocaloric 24-h interventions (55%, 30%, and 15% carbohydrate, fat and protein, respectively): a breakfast skipping day (BSD) and a dinner skipping day (DSD) separated by a conventional 3-meal-structure day (control). Energy and macronutrient balance were measured and postprandial glucose and insulin concentrations, as well as 24-h glycemia and 24-h insulin secretion (C-peptide), were analyzed. When compared with the 3-meal control, 24-h energy expenditure was higher on DSD (DSD: +69 kcal/d; p < 0.05), but not on BSD. Whereas, fat oxidation increased on the BSD only (+13 g/d; p < 0.01). Spontaneous physical activity, 24-h glycemia, and 24-h insulin secretion did not differ between intervention days. The postprandial homeostasis model assessment index (+54%) and glucose concentrations after lunch (+46%) were, however, higher on the BSD than on the DSD (both p < 0.05). When compared with 3 meals/d, dinner skipping increased energy expenditure. In contrast, higher postprandial insulin concentrations and increased fat oxidation with breakfast skipping show the development of metabolic inflexibility in response to prolonged fasting that may in the long-term lead to impaired glucose homeostasis. The study on energy flux includes 16 healthy participants who underwent three 24-h interventions with different levels of EF: (i) low EF, physical activity level (PAL) = 1.3 – 1.4 (ii) medium EF, PAL = 1.5 – 1.6 and (iii) high EF, PAL = 1.7 – 1.8 each at energy balance (EB), caloric restriction (CR), and overfeeding (OF) (100%, 75% and 125% of individual energy requirement with 50% carbohydrate, 35% fat, 15% protein). Different levels of EF were accomplished by walking (4 km/h) on a treadmill (0, 165 and 330 min). Sleeping energy expenditure (SEE), 24-h macronutrient oxidation and relative macronutrient balance (oxidation relative to intake) were determined. During EB and OF, 24-h fat oxidation increased with higher EF. This resulted in a higher relative fat balance at medium EF (EB: +17%, OF: +14%) and high EF (EB: +23%, OF: +17%) compared to low EF (all p < 0.05). SEE during EB and OF was higher at medium (EB: +5 kcal/3h and OF: +12 kcal/3h) and high (EB: +7 kcal/3h and OF: +18 kcal/3h) EF compared to low EF (all, p < 0.05). In contrast, during CR 24-h fat oxidation was only higher at high EF compared to low EF and neither relative fat balance nor SEE differed between the EF levels. A higher EF might have beneficial effects on body weight regulation during short-term overfeeding and energy balance because it increased SEE and improved relative fat balance. However, during short-term caloric restriction, a higher EF had no impact on the regulation of energy or fat balance. Therefore, a high EF especially can attenuate the adverse effects of short-term overfeeding. Altogether, this thesis emphasizes the importance of physical activity in daily life and suggests that the adverse metabolic outcome of breakfast skipping (caused by a positive energy balance after lunch with a preceding prolonged fasting period) might be attenuated by a high EF.