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Results for “dietary environments”

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At least 19 recordsLinked to original sources
PubMed1978

Lysine requirement of broilers as influenced by environmental temperatures.

Two experiments were conducted to determine the influence of 15.6 and 29.4 degrees C. environmental temperatures on 2- to 4-week broiler lysine requirements. Weights for 4-week-old cockerels were maximum when either 1.10% dietary lysine in the 15.6 degrees C. environment or 1.00% dietary lysine in the 29.4 degrees C. environment were fed. Feed was used more efficiently by 4-week old cockerels fed either 1.10% dietary lysine in the 15.6 degrees C. environment or 0.95% dietary lysine in the 29.4 degrees C. environment. Plasma free lysine concentrations from 4-week-old cockerels increased as dietary lysine increased. Total plasma free amino acid concentrations from chicks grown in a 15.6 degrees C. environment were approximately 25% greater than from chicks grown at 29.4 degrees C. Total plasma free amino acids for 4-week-old cockerels peaked when 1.05% dietary lysine in the cool environment and 0.95% dietary lysine in the warm environment were fed.

Amino Acids↗
PubMed2026

Genome-Wide Association Analysis for Growth-Related Traits in Indoor- and Outdoor-Cultured Juvenile Grass Carp (Ctenopharyngodon idella).

Grass carp is a key herbivorous freshwater fish, yet long-term inbreeding reduces growth rates. Current genome-wide association studies (GWAS) primarily focus on a limited range of growth traits, while intestinal morphology is likely to emerge as a promising new proxy for both growth performance and health status. We reared juvenile grass carp from one batch in indoor vs. natural aquatic vegetation groups for 100 days, measuring body weight (BW), length (BL), height (BH), and intestinal length (IL) in 200 individuals (100/group). Phenotypic differences were significant for all traits, with IL most variable. GWAS identified 95 significant SNPs, among which 21 were related to multiple traits. Candidate gene and KEGG pathway analyses linked these SNPs to myogenesis, skeletal development, immunity, calcium signaling, and stress resistance. Twelve SNPs were found to be associated with IL, including 8 multi-trait-related and 4 trait-specific ones. This suggests that IL can serve as a supplementary growth trait. There was no overlap with prior GWAS, but recurrent signals on chromosomes 1, 2, 14 (BW) and 2, 3, 14, 24 (BH) merit further study. Our findings enrich molecular resources for grass carp and highlight IL's potential for marker-assisted breeding.

Ctenopharyngodon idella↗
PubMed1978

Interaction of dietary fiber with other dietary components: a possible factor in certain cancer etiologies.

Dietary fiber is a highly interacting dietary component and is made up of a wide variety of enzyme-indigestible polymers: cellulose, pectins, gums, mucilages, lignin, and water-insoluble hemicelluloses. The study of the effect of dietary fiber on prevention of cancer, specifically of colonic cancer, cannot be carried on without considering that: 1) various types of dietary fiber have different metabolic effect; 2) other components of the diet (e.g., amount of fat) may influence the way dietary fiber affects the colonic environment; 3) the overall effect of dietary fiber may be the sum of effects on fecal bulk, colonic microflora pattern and metabolites, dilution of carcinogens, colonic pH, transit time, alteration of nutrient absorption, and postprandial hormonal function. It is unlikely that dietary fiber can be studied in isolation in experimental diets unless great care is taken to consider all interactions with other dietary components.

Cellulose↗
PubMed2026

Post-colonial human admixture and natural selection: disentangling signals in complex demographic contexts.

Natural selection and admixture are defining population genetic features of modern human populations, yet their interaction has only recently emerged as a major focus in human evolutionary genomics. While the influence of natural selection on population structure and trait diversity is well established, the ways in which selective pressures operate after admixture have historically received far less attention. In this review, we synthesise the latest progress in understanding post-admixture selection and highlight case studies that illustrate how novel environments, pathogen exposure, dietary shifts and socio-historical transformations have driven genomic adaptation. We conclude by identifying key gaps that remain in the field with the aim of motivating future research and facilitating new insights into how admixture and selection jointly shape human diversity.

Journal Article↗
PubMed1975

Spina bifida and anencephaly: miscarriage as possible cause.

In two retrospective Liverpool surveys the domestic, family, dietary, and medical environments of the mothers of children affected by anencephaly or spina bifida, or both (ASB) were examined. None seemed to be of more than minor importance and the findings of others were therefore examined to see if they suggested a major factor. The most promising lead came from the hypothesis that ASB is usually due to an interaction between twin fetuses or between a fetus and residual trophoblastic material from the previous normal pregnancy, particularly when this is of the opposite sex to the propositus. The sex finding was not confirmed. It was noted that hydatidiform moles, like children with ASB, were usually female and that moles and choriocarcinomas on the one hand and children with ASB on the other occurred in mothers of similar ages, but were to some extent reciprocal in geographical incidence. This suggested that trophoblastic disease might be a factor common to all three and if so then one would expect the frequency of miscarriages to be higher immediately before than immediately after the birth of an ASB child, since mole and choriocarcinoma seldom follow a normal pregnancy. An analysis of published data confirmed that this was almost certainly so. Hence residual pathological trophoblastic material from either a previous miscarriage or a co-twin may interact unfavourably with another fetus to produce ASB and this may be the primary cause of the condition. The hypothesis is consistent with the observed lack of concordance in twins, the high incidence in females, the maternal age effect, and the greater prevalence in social classes IV and V.

Abortion, Spontaneous↗
PubMed1978

Nutritional success in a semi-arid land: examination of Tswana agro-pastoralists of the eastern Kalahari, Botswana.

The cultural and environmental factors affecting the food quest and nutritional status of the Moshaweng Tlokwa, a Tswana agro-pastoral society occupying the semi-arid eastern Kalahari Desert of Botswana, are examined. Data are presented on methods of food procurement, storage, preparation, and preservation. Tlokwa diet is based on agriculture horticulture and animal husbandry but a surprising number of wild species are regularly used as food. This pattern is nutritionally protective and viewed by the author as a principal reason for Tlokwa dietary success in their semi-arid environment. Data are presented on food habits, dietary prohibitions, and characteristic diets of infants, children, adolescents, and adults. Many Tlokwa foods are encouraged or prohibited on the basis of the consumers age, sex, and social development. Such patterns reduce competition for dietary resources, assure a more equitable distribution of food, and sustain the nutritional quality of diet. During 1973 to 1975 the Tlokwa appeared healthy and well fed; heavy rain-fall had just broken a 7-year drought. Kwashiorkormarasmus, avitaminosis, or other classical signs of malnutrition were not observed. A trend towards bottle feeding was noted. Children and adolescents are rapidly losing their ability to identify edible wild food resources. The author concludes that the Tlokwa heretofore have coped satisfactorily with drought in their semi-arid territory and recommends continued diversification of their food quest. Diversity is viewed as essential if the Tlokwa are to maintain their nutritional well-being in coming decades.

Adolescent↗
PubMed1979

Genetic and biological variability in human nutrient requirements.

Multiple factors, associated with the host and environment, as well as the chemical form of the nutrient, its availability, chemical and metabolic interactions among nutrients, result in a variability in nutrient requirements that is probably well beyond that observed in controlled laboratory studies of small groups of "normal" healthy subjects. Although many factors are recognized as contributing to the variation in human nutrient requirements, current knowledge is largely of qualitative significance: Garn (40) state that this level of knowledge and investigation "has a long past but no foreseeable future." It is sad commentary that neither do we know adequately the quantitative extent of biological variation in requirements among individuals for any of the essential nutrients nor the quantitative importance of most of the factors which affect requirements in population groups. We believe that the potential contributions of nutrition toward solving problems of human disease and for maintaining health in populations depend as much on a better definition of the quantitative aspects of human nutrient requirements as on improved understanding of the utilization, function and metabolism of nutrients at the cellular, organ, and whole body level.

Adult↗
PubMed1977

Diet, DDT, and the toxicity of drugs and chemicals.

The toxic and carcinogenic effects of many compounds depend on their activation to reactive molecules in the cytochrome P-450 system of the endoplasmic reticulum of cells. Changes in dietary input alter P-450 levels in different tissues and so alter toxicity. In this way, low protein diets protect against carbon tetrachloride poisoning. Fats, proteins, and nonnutrients such as flavones, antioxidants, and contaminants like DDT all affect P-450 levels. The activated molecules may be diverted from their target sites by inactivation processes, such as epoxide hydratase or glutathione trappin. This is also under nutritional control. Low protein diets render animals sensitive to acetaminophen by reducing glutathione levels. In the sequence of events leading from initial contact of toxin with organism to eventual cell injury or neoplasm, nutritional factors are of import at every stage. Assessments of the toxicity of chemicals that do not take into account the nutritional variable in man are likely to be incorrect.

Acetaminophen↗
PubMed1977

Two-stage control of cell proliferation induced in rat liver by alpha-hexachlorocyclohexane.

Determinants of the timing of DNA synthesis in rat liver were studied, using alpha-hexachlorocyclohexane as a tool for stimulation of cell proliferation. One determinant is the time of alpha-hexachlorocyclohexane administration. The increase in DNA synthesis starts after a lag phase (prereplicative phase) of minimally 20 hr. Use of animals adapted to a controlled feeding and lighting schedule revealed a second determinant provided by food consumption. Initiation of DNA synthesis is suppressed by fasting or protein deprivation and occurs 5 to 8 hr after readministration of a protein-containing diet. The light-dark rhythm has no direct influence on the timing of DNA synthesis. Stimulation of hepatic DNA synthesis, therefore appears to require two different sequential signals. The first is provided by alpha-hexachlorocyclohexane, and the second is provided by protein intake. In the absence of the second signal, committed cells are arrested at a critical point of the prereplicative phase and accumulate. Protein intake permits release from the block, and the accumulated cells enter the S period almost synchronously after completion of the remaining 5 to 8 hr of the prereplicative phase. These observations provide a means of synchronizing, in the living animal, a proliferating population of hepatocytes. In addition, they offer an explanation for the diurnal rhythmicity in the rate of hepatic cell proliferation.

Animals↗
PubMed1978

Pig-bel--a zoonosis?

It is postulated that the combination of a very low protein diet, with low pancreatic tryptic activity, plus the continual consumption of sweet potato trypsin inhibitors leads to inadequate proteolysis when a meal containing meat contaminated with C. perfringens type C and its beta toxin is consumed. The necrotizing pathogenic process concluding as segmental gangrene is set in motion by toxin produced under altered dietary conditions first by motor paralysis via beta toxin, followed by villous attachment and colonisation by ingested or resident C. perfringens type C in the gut. Necrobiosis is maintained by further toxin production which may be blocked in immune individuals. The endemicity of the disease is governed by the amount of C. perfringens type C in both the general and gut environments, the latter determined by dietary influences and the protein nutrition of the host. A hypothesis put forward is that the organism is carried and dispersed by the domestic pig and man becomes an incidental host. Infectivity only occurs when critical ecological factors exist in the small gut of humans. Prevention in the short term is possible with a toxoided vaccine using three injections given at one month and twelve month intervals.

Animals↗
PubMed1976

Role of residual olfactory cues in the determination of feeding site selection and exploration patterns of domestic rats.

Weanling domestic rat pups feed and explore in areas containing residual olfactory cues deposited by conspecific adults in preference to clean areas. Both nulliparous and lactating Long-Evans female rats deposit residual cues in an area that induce pups to explore and feed in it. Residual cues continue to affect the feeding and exploratory behavior of pups to maturity. Discrepancies between results obtained in the olfactory discrimination apparatus used by Leon and Moltz and those of the present experiments are resolved, and evidence is presented for the existence of residual cues not contained in anal excreta, which are attractive to pups. It is suggested that residual cues deposited by adult rats can play a role in directing weanlings to their first meals of solid food in the natural environment.

Animals↗