The food matrix of spinach is a limiting factor in determining the bioavailability of beta-carotene and to a lesser extent of lutein in humans.
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Carotenoid bioavailability depends, amongst other factors, on the food matrix and on the type and extent of processing. To examine the effect of variously processed spinach products and of dietary fiber on serum carotenoid concentrations, subjects received, over a 3-wk period, a control diet (n = 10) or a control diet supplemented with carotenoids or one of four spinach products (n = 12 per group): whole leaf spinach with an almost intact food matrix, minced spinach with the matrix partially disrupted, enzymatically liquefied spinach in which the matrix was further disrupted and the liquefied spinach to which dietary fiber (10 g/kg wet weight) was added. Consumption of spinach significantly increased serum concentrations of all-trans-beta-carotene, cis-beta-carotene, (and consequently total beta-carotene), lutein, alpha-carotene and retinol and decreased the serum concentration of lycopene. Serum total beta-carotene responses (changes in serum concentrations from the start to the end of the intervention period) differed significantly between the whole leaf and liquefied spinach groups and between the minced and liquefied spinach groups. The lutein response did not differ among spinach groups. Addition of dietary fiber to the liquefied spinach had no effect on serum carotenoid responses. The relative bioavailability as compared to bioavailability of the carotenoid supplement for whole leaf, minced, liquefied and liquefied spinach plus added dietary fiber for beta-carotene was 5.1, 6.4, 9.5 and 9.3%, respectively, and for lutein 45, 52, 55 and 54%, respectively. We conclude that the bioavailability of lutein from spinach was higher than that of beta-carotene and that enzymatic disruption of the matrix (cell wall structure) enhanced the bioavailability of beta-carotene from whole leaf and minced spinach, but had no effect on lutein bioavailability. (+info)
Variation in ruminants' preference for tall fescue hays cut either at sundown or at sunup.
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Plants vary diurnally in concentrations of nonstructural carbohydrates. If ruminants prefer forages with higher total nonstructural carbohydrates (TNC), then the preference for hays harvested within the same 24-h period may vary. An established field of tall fescue (Festuca arundinacea Schreb.) was harvested six times in the vegetative stage. Harvests were paired such that each cutting at sundown (PM) was followed by a cutting the next morning at sunup (AM). We harvested in this manner three times, resulting in six hays. The hays were field-dried, baled, and passed through a hydraulic bale processor prior to feeding. Experiments were conducted with sheep, goats, and cattle, using six animals in each case. During an adaptation phase, hays were offered alone as meals. In the experimental phase, every possible pair of hays (15 pairs) was presented for a meal. Data were analyzed by multidimensional scaling and by traditional analyses. Multidimensional scaling indicated that selection was based on a single criterion. Preference for PM hays was greater than for AM hays (P < .01) in all experiments. Increased preference was associated with increased TNC (P < .01) and in vitro true DM disappearance (P < .01) and decreased fiber concentration (P < .01; NDF, ADF, cellulose, and ADL). Mowing hay late in the day was effective in increasing forage preference. (+info)
The energy content of barley fed to growing pigs: characterizing the nature of its variability and developing prediction equations for its estimation.
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Currently, the pork industry attempts to formulate energy levels in swine diets to within a tolerance of 1.5%. This is difficult to achieve in practice when the energy content of primary ingredients fluctuates by up to 15%. This experiment was carried out to define the sources of variation in the energy content of barley and to develop a practical method to accurately estimate the DE and ME content of individual barley samples. Four samples of each of five covered barley varieties (AC Lacombe, B-1602, Bedford, Harrington, and Manley) were collected to obtain a range of quality within each variety. Five measurements were collected on each barley sample using 60 crossbred barrows in an apparent total tract digestibility study. The barrows, average BW of 35.3 kg, were housed in individual metabolism crates to facilitate separate collection of urine and feces. Five-day collection periods followed 5-d diet acclimation periods. Levels of total beta-glucan, ADF, CP, and starch (90% DM) in the 20 barley samples ranged from 2.7 to 4.5%, 4.5 to 9.2%, 10.8 to 15.1%, and 42.3 to 53.4%, respectively. The mean DE and ME content of the 20 samples were 2,934 and 2,857 kcal/kg (90% DM), respectively, and varied among samples by 15.2% (447 kcal). The complex structural cell wall carbohydrates seemed to have the greatest influence on the energy content of individual barley samples. The ADF fraction alone accounted for 85% of the total variation in energy content of the 20 samples. Converted into a prediction equation, DE = 3,526 - 92.8 x ADF (90% DM), the ADF content was used to estimate the DE content of barley with 85% accuracy. This experiment confirms the large variation in the energy content of barley, describes the factors that influence this variation, and presents equations based on chemical and(or) physical measurements that may be used to predict the DE and ME content of individual barley samples. (+info)
Impact of amino acid nutrition during lactation on body nutrient mobilization and milk nutrient output in primiparous sows.
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The impact of amino acid nutrition during lactation on body nutrient mobilization and milk nutrient output in primiparous sows was evaluated. Thirty-six sows, nursing litters of 13 pigs, were allocated daily 6 kg of a fortified corn-soybean meal diet containing a high (HP, 1.20% lysine) or low (LP, .34% lysine) protein content during a 23-d lactation. Dietary lysine concentration was achieved by altering the ratio of corn and soybean meal in the diet. The LP sows consumed less daily ME (14.2 vs 16.1 Mcal; P < .11) and daily lysine (16 vs 59 g; P < .01) than the HP sows. Daily litter weight gain was less (P < .01) for sows fed the LP vs HP diet, and the differences increased (P < . 01) as lactation progressed. The lower litter weight gain for the LP sows was reflective of the lower (P < .01) estimated milk DM, CP, and GE output of these sows. The LP sows lost more body weight (1.23 vs .21 kg/d; P < .01) during the initial 20 d of lactation. In the LP sows, 59% of the weight loss was protein, water, and ash, and 37% was fat. Weight loss in the HP sows was entirely accounted for by body fat mobilization, because these sows accrued body protein, water, and ash. Muscle myofibrillar breakdown rate was higher in LP sows than in HP sows (4.05 vs 2.80%/d; P < .01). On the basis of these data, dietary amino acid restriction during lactation increases maternal mobilization of proteinaceous tissue and reduces milk nutrient output. Maternal protein mobilization is maintained over the entire lactation even though milk output is decreased as lactation progresses. (+info)
Inulin and oligofructose: what are they?
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Inulin is a term applied to a heterogeneous blend of fructose polymers found widely distributed in nature as plant storage carbohydrates. Oligofructose is a subgroup of inulin, consisting of polymers with a degree of polymerization (DP) +info)
Expression of the insecticidal bean alpha-amylase inhibitor transgene has minimal detrimental effect on the nutritional value of peas fed to rats at 30% of the diet.
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The effect of expression of bean alpha-amylase inhibitor (alpha-AI) transgene on the nutritional value of peas has been evaluated by pair-feeding rats diets containing transgenic or parent peas at 300 and 650 g/kg, respectively, and at 150 g protein/kg diet, supplemented with essential amino acids to target requirements. The results were also compared with the effects of diets containing lactalbumin with or without 0.9 or 2.0 mg bean alpha-AI, levels equivalent to those in transgenic pea diets. When 300 and 650 g peas/kg diet were fed, the daily intake of alpha-AI was 11.5 or 26.3 mg alpha-AI, respectively. At the 300 g/kg level, the nutritional value of the transgenic and parent line peas was not significantly different. The weight gain and tissue weights of rats fed either of the two pea diets were not significantly different from each other or from those of rats given the lactalbumin diet even when this was supplemented with 0.9 g alpha-AI/kg. The digestibilities of protein and dry matter of the pea diets were slightly but significantly lower than those of the lactalbumin diet, probably due to the presence of naturally occurring antinutrients in peas. The nutritional value of diets containing peas at the higher (650 g) inclusion level was less than that of the lactalbumin diet. However, the differences between transgenic and parent pea lines were small, possibly because neither the purified recombinant alpha-AI nor that in transgenic peas inhibited starch digestion in the rat small intestine in vivo to the same extent as did bean alpha-AI. This was the case even though both forms of alpha-AI equally inhibited alpha-amylase in vitro. Thus, this short-term study indicated that transgenic peas expressing bean alpha-AI gene could be used in rat diets at 300 g/kg level without major harmful effects on their growth, metabolism and health, raising the possibility that transgenic peas may also be used at this level in the diet of farm animals. (+info)
Effects of underfeeding and refeeding on weight and cellularity of splanchnic organs in ewes.
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We assessed the effects of a long and severe period of underfeeding, followed by a rapid refeeding with a high-concentrate diet, on weight, protein mass, and cellularity of the splanchnic organs in adult ewes. Twenty-four ewes, allocated to four groups of six, were fed a forage diet (50% regrowth of natural grassland hay and 50% wheat straw) either at maintenance (groups M and MO) or at 40% maintenance (groups U and UO) for 78 d. Groups M and U were then slaughtered, and groups MO and UO were subsequently overfed a high-concentrate diet (52% hay, 20% barley, 16% rapeseed meal, 4% fish meal, and 8% Megalac) at 236% maintenance for 26 d before being slaughtered. During the experiment, feed was adjusted to maintain feed supply at a constant percentage of animal requirements. After slaughter, fresh weight, dry weight, and protein mass of the reticulorumen, omasum, abomasum, small intestine, large intestine, and liver were measured. Cellularity was assessed from nucleic acids and protein contents for both ruminal mucosa and muscular-serosa layers, jejunum, and liver. The concentrations of ubiquitin and cathepsin D mRNA were measured in ruminal mucosa and muscular-serosa layers and in jejunum. Underfeeding decreased protein mass of splanchnic organs, especially in liver (-29%) and reticulorumen (-39%). Refeeding previously underfed animals increased protein mass of liver (+102%) and small intestine (+59%). No carry-over effect of the previous level of intake (UO vs. MO) was observed on the protein mass of splanchnic tissues after 26 d of refeeding. Variations in liver mass were mainly due to hypertrophy, as determined by the protein:DNA ratio, whereas variations in small intestinal mass were mainly due to hyperplasia, as determined by the amount of DNA. By contrast, changes in rumen mass associated with increasing ME intake seemed to be related to hypertrophy in the muscular-serosal component and hyperplasia in the epithelial component. The concentrations of ubiquitin and cathepsin D mRNA in the rumen and jejunum were not modified by feeding level, demonstrating that the expression of these genes for proteolytic enzymes was unchanged under these conditions. (+info)
Legumes and soybeans: overview of their nutritional profiles and health effects.
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Legumes play an important role in the traditional diets of many regions throughout the world. In contrast in Western countries beans tend to play only a minor dietary role despite the fact that they are low in fat and are excellent sources of protein, dietary fiber, and a variety of micronutrients and phytochemicals. Soybeans are unique among the legumes because they are a concentrated source of isoflavones. Isoflavones have weak estrogenic properties and the isoflavone genistein influences signal transduction. Soyfoods and isoflavones have received considerable attention for their potential role in preventing and treating cancer and osteoporosis. The low breast cancer mortality rates in Asian countries and the putative antiestrogenic effects of isoflavones have fueled speculation that soyfood intake reduces breast cancer risk. The available epidemiologic data are limited and only weakly supportive of this hypothesis, however, particularly for postmenopausal breast cancer. The data suggesting that soy or isoflavones may reduce the risk of prostate cancer are more encouraging. The weak estrogenic effects of isoflavones and the similarity in chemical structure between soybean isoflavones and the synthetic isoflavone ipriflavone, which was shown to increase bone mineral density in postmenopausal women, suggest that soy or isoflavones may reduce the risk of osteoporosis. Rodent studies tend to support this hypothesis, as do the limited preliminary data from humans. Given the nutrient profile and phytochemical contribution of beans, nutritionists should make a concerted effort to encourage the public to consume more beans in general and more soyfoods in particular. (+info)