Nutrient Requirements For Growth Research Articles

Computation of condition-dependent proteome allocation reveals variability in the macro and micro nutrient requirements for growth.

Sustaining a robust metabolic network requires a balanced and fully functioning proteome. In addition to amino acids, many enzymes require cofactors (coenzymes and engrafted prosthetic groups) to function properly. Extensively validated resource allocation models, such as genome-scale models of metabolism and gene expression (ME-models), have the ability to compute an optimal proteome composition underlying a metabolic phenotype, including the provision of all required cofactors. Here we apply the ME-model for Escherichia coli K-12 MG1655 to computationally examine how environmental conditions change the proteome and its accompanying cofactor usage. We found that: (1) The cofactor requirements computed by the ME-model mostly agree with the standard biomass objective function used in models of metabolism alone (M-models); (2) ME-model computations reveal non-intuitive variability in cofactor use under different growth conditions; (3) An analysis of ME-model predicted protein use in aerobic and anaerobic conditions suggests an enrichment in the use of peroxyl scavenging acids in the proteins used to sustain aerobic growth; (4) The ME-model could describe how limitation in key protein components affect the metabolic state of E. coli. Genome-scale models have thus reached a level of sophistication where they reveal intricate properties of functional proteomes and how they support different E. coli lifestyles.

Bacterial Cell, Classification and Required Essential Contents for Growth

The bacterial cell is generally single cellular micro organism that spread easily around us and infect host cell. In this review we discuss about the types and nutrient requirements for growth and spreading of bacteria. The bacteria are various types like as Phototrophs, Autotrophs, Psychrophiles, Mycoplasma etc.

生态恢复对马尾松叶片化学计量及氮磷转移的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 生态恢复对马尾松叶片化学计量及氮磷转移的影响 DOI: 10.5846/stxb201510182100 作者: 作者单位: 福建师范大学地理科学学院,福建师范大学地理研究所,福建师范大学地理科学学院,福建师范大学地理科学学院,福建师范大学地理科学学院,福建师范大学地理科学学院,福建师范大学地理研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31370465）；国家科技部973计划课题资助项目（2012CB722203） Effects of ecological restoration on stoichiometric characteristics and nutrient resorption efficiency of Pinus massoniana foliage Author: Affiliation: College of Geographical Science, Fujian Normal University,Institute of Geography, Fujian Normal University,College of Geographical Science, Fujian Normal University,College of Geographical Science, Fujian Normal University,College of Geographical Science, Fujian Normal University,College of Geographical Science, Fujian Normal University,Institute of Geography, Fujian Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了解生态恢复对侵蚀红壤恢复的马尾松林叶片碳氮磷化学计量及氮磷养分转移的影响，在福建省长汀县河田镇典型侵蚀红壤区选取恢复13、30、33a的马尾松林为研究对象，并以未治理侵蚀地（CK1）和次生林（CK2）分别作为恢复前和恢复后的对照，通过测定马尾松叶片的碳、氮、磷含量，计算其计量比，内稳性指数和氮磷转移率，分析了侵蚀红壤生长的马尾松养分限制与养分转移的关系。结果表明：在侵蚀红壤恢复过程中，马尾松1年龄叶片C、N、P含量及1年龄叶片C：N、C：P、N：P变化较小，这与马尾松较高的内稳性有关（N和P内稳性指数分别为7.57和3.89）。所有实验地马尾松1年龄叶片N：P处于11.0-13.4之间，表明马尾松的生长受N、P共同限制，其中马尾松叶片N转移率显著低于P转移率，这与生态恢复过程中马尾松养分利用效率、生长需求以及土壤养分供应状况有关。1年龄叶片C：N、C：P分别与马尾松N、P转移率成负相关关系，当马尾松叶片C：N、C：P较低时，表明N、P利用效率较低，叶片衰老时更多的N和P被转移利用；反之，则N、P利用效率较高，转移率低。同时，C：N、C：P分别与树高、胸径成显著负相关关系，即马尾松生长对N、P的需求同样会影响化学计量比的变化，从而影响养分转移。虽然侵蚀地生态恢复过程中土壤N、P含量增加，但仍较贫瘠，不足以满足马尾松的生长，马尾松养分转移率较高，因此，为了提高侵蚀地恢复的马尾松林的生产力，建议下一步恢复措施中适当施加N肥和P肥。该研究将侵蚀红壤不同生态恢复年限的马尾松叶片C、N、P化学计量及养分转移结合，有助于全面、系统地揭示生态恢复过程马尾松林的养分循环，对指导侵蚀红壤恢复和提高马尾松生产力具有重要意义。 Abstract:Carbon (C), nitrogen (N), and phosphorus (P) content are important indexes for forest management that respond positively to environmental conditions. In recent years, stoichiometry has received considerable attention. However, few studies have reported the patterns of soil-plant stoichiometry and nutrient resorption during ecological restoration. The goal of the study was to investigate the effects of ecological restoration on stoichiometric characteristics and nutrient resorption efficiency of Pinus massoniana foliage. We used P. massoniana as our research species and determined variations in leaf C, N, and P content. The content of foliar N and P were used to estimate stoichiometric ratios, homeostatic indexes, and nutrient resorption efficiencies across years during ecological restoration at five sites. Four of the five P. massoniana woodlands were restored at 0 (CK1), 13, 30, and 33 years, and one was a secondary forest (CK2). These study sites were expected to differ based on the level of ecological restoration (years) in the typical eroded red soil region in Hetian Town, Changting County, Fujian Province. The results revealed no considerable changes in the C, N, or P content of one-year old foliage of P. massoniana during the restoration process on degraded red soil. The same observations were made for the C:N, C:P, and N:P ratios because P. massoniana has strong homeostatic mechanisms (N and P homeostatic indexes were 7.57 and 3.89, respectively). The N:P of foliage at the five sites was between 11.0 and 13.4. There may have been some degree of N and P co-limitation of P. massoniana growth in the eroded red soil region. However, N resorption efficiency was significantly lower than P resorption efficiency. This was related to P. massoniana nutrient use efficiency, nutrient requirements for growth, and soil nutrient availability. In addition, there was a negative correlation between the ratios (C:N and C:P) and resorption efficiency of one-year old foliage of P. massoniana. Furthermore, one-year old foliage of P. massoniana substantially exhibited lower N and P use efficiencies as the C:N and C:P ratios increased. As such, more nutrients could be resorbed. The opposite occurred when C:N and C:P ratios were low. Furthermore, the C:N and C:P ratios of one-year old foliage of P. massoniana were negatively correlated with tree height and diameter at breast height, respectively. This suggests that nutrient demands for the growth of P. massoniana affect the stoichiometric ratios and N and P resorption. In brief, the N and P contents increased during the restoration process in degraded red soil; in other words, this explains the slow recovery and still relatively infertile status of eroded areas. The soil nutrients cannot sufficiently support the growth of P. massoniana, which leads to relatively higher N and P resorption rates. Thus, in order to improve P. massoniana forest productivity, we suggest increasing N and P fertilizer to increase soil fertility. This study helped to clarify the nutrient cycling of P. massoniana woodlands by combining P. massoniana foliage C, N, and P stoichiometric characteristics and nutrient resorption in a comprehensive and systematic manner. Therefore, it is important to manage the ecological restoration of eroded red soil, and efforts improve the productivity of forest systems should be conducted. 参考文献 相似文献 引证文献

Uncertainty in carbon allocation strategy and ecophysiological parameterization influences on carbon and streamflow estimates for two western US forested watersheds

Increasingly sophisticated process-based ecosystem models account for the ability of plants to vary the proportion of net photosynthate that is allocated to individual organs – such as leaves, stems and roots. Because the governing mechanisms are still not well understood, models differ in the strategies used to represent carbon allocation processes. Allocation schemes may have important implications for ecosystem structure and biogeochemical cycling, thus there is a need to better understand how different carbon allocation strategies influence estimates of variables that are of interest to model users. At the same time, uncertainty in other ecophysiological parameters that are commonly used in carbon cycling models may influence these estimates and interact with different carbon allocation strategies. We use a coupled ecohydrologic model to understand how uncertainty in three relatively simple allocation strategies affects carbon (C) and streamflow estimates in two case study forested mountain watersheds in the western United States: a relatively wet site located in the western Oregon Cascades, and a drier site in California’s Sierra Nevada. Ecophysiological parameters controlling productivity rates, morphology, and nutrient requirements for growth are varied as well. The influence of specific ecophysiological parameters and allocation strategies on C sequestration and streamflow estimates differed between sites. At the wetter site, uncertainty in C cycling processes resulted in a three-fold difference in potential sequestered carbon, but had a negligible effect on annual and low monthly streamflow estimates. Conversely, at the drier site, C pool estimates showed limited sensitivity to ecophysiological parameter uncertainty, but considerable difference in annual and low monthly streamflow estimates across ecophysiological assumptions. At both sites, stemwood C pool estimates exceeded literature-derived field values when branch mortality—a surrogate for density thinning—was not included in addition to background mortality. Despite using site- and species-specific information, we are unable to invalidate any of the allocation strategies considered. Our results suggest that uncertainty in parameterization of ecophysiological parameters and assumptions about carbon allocation can strongly influence model estimates of both streamflow and forest carbon sequestration potential, but that influence is likely to vary with site bioclimatic characteristics.

Nutritional Considerations for the Overweight Young Athlete.

Nutritional considerations for the overweight young athlete have not been thoroughly discussed in the scientific literature. With the high prevalence of childhood obesity, more children participating in sports are overweight or obese. This is particularly true for select sports, such as American football, where large size provides an added advantage. While sport participation should be encouraged because of the many benefits of physical activity, appropriate nutritional practices are vital for growth, and optimizing performance and health. The overweight young athlete may face certain challenges because of variable energy costs and nutrient requirements for growth and routine training, compared with nonoverweight athletes. Special attention should be given to adopting healthy lifestyle choices to prevent adverse health effects due to increased adiposity. In this review, we aim to discuss special nutritional considerations and highlight gaps in the literature concerning nutrition for overweight young athletes compared with their nonoverweight peers.

Data needs for B-24 and beyond: NHANES data relevant for nutrition surveillance of infants and young children

The period from birth to 24 mo (B-24) is a critical phase in which nutrient requirements for growth and development are high and several transitions in food consumption practices occur. A few large-scale national studies (eg, the Feeding Infants and Toddlers Study and Infant Feeding Practices Study) offer important insights into infant feeding practices and food consumption patterns in young children in the United States. The NHANES collects comprehensive cross-sectional data on the nutrition and health of Americans including infants and toddlers. This article describes the NHANES program and data from NHANES 1999-2010 on young children that are relevant for the B-24 Project. NHANES is a nationally representative survey of the noninstitutionalized US population that combines personal interviews with standardized physical examination and measurements via mobile examination centers. Data on infant feeding practices (breastfeeding and timing of introduction and nature of complementary foods), dietary intake (two 24-h recalls), and nutrient supplements are collected. Data on demographic characteristics, anthropometric measurements, biomarkers of nutrient status, food security, and participation in federal nutrition programs are also available. Data can be accessed online, downloaded, and pooled over several survey cycles, allowing examination of infant feeding practices, food and nutrient intakes, and nutritional status of Americans <2 y old. Subgroup analyses by race-ethnicity and income status are also possible. NHANES responds to evolving data needs, as feasible, in the context of the survey design, research priorities, and funding. It offers a vehicle for potentially gathering additional data on children <2 y to address the objectives of the B-24 Project in the future.

Gluten-Free Diet in Children: An Approach to a Nutritionally Adequate and Balanced Diet

Gluten-free diet (GFD) is the cornerstone treatment for celiac disease (CD). GFD implies a strict and lifelong elimination from the diet of gluten, the storage protein found in wheat, barley, rye and hybrids of these grains, such as kamut and triticale. The absence of gluten in natural and processed foods, despite being the key aspect of GFD, may lead to nutritional consequences, such as deficits and imbalances. The nutritional adequacy of GFD is particularly important in children, this the age being of maximal energy and nutrient requirements for growth, development and activity. In recent years, attention has focused on the nutritional quality of gluten-free products (GFPs) available in the market. It is well recognized that GFPs are considered of lower quality and poorer nutritional value compared to the gluten-containing counterparts. The present review focuses on the nutritional adequacy of GFD at the pediatric age, with the aim being to increase awareness of the potential complications associated with this diet, to identify strategies in order to avoid them and to promote a healthier diet and lifestyle in children with CD.

Nutritional factors influencing intestinal health of the neonate.

Dietary nutrients are essential for gastrointestinal (GI) growth and function, and nutritional support of GI growth and development is a significant component of infant care. For healthy full-term neonates, nutritional provisions of the mother's milk and/or formula will support normal maturation of structure and function of the GI tract in most infants. The composition of breast milk affects GI barrier function and development of a competent mucosal immune system. The functional nutrients and other bioactive components of milk support a microenvironment for gut protection and maturation. However, premature infants struggle with feeding tolerance impairing normal GI function, leading to intestinal dysfunction and even death. The high prevalence worldwide of enteric diseases and dysfunction in neonates has led to much interest in understanding the role of nutrients and food components in the establishment and maintenance of a functioning GI tract. Neonates who do not receive enteral feeding as either mother's milk or formula are supported by total parental nutrition (TPN). The lack of enteral nutrition can compound intestinal dysfunction, leading to high morbidity and mortality in intestinally compromised infants. Reciprocally, enteral stimulation of an immature GI tract can also compound intestinal dysfunction. Therefore, further understanding of nutrient interactions with the mucosa is necessary to define nutritional requirements of the developing GI tract to minimize intestinal complications and infant morbidity. Piglet models of intestinal development and function are similar to humans, and this review summarizes recent findings regarding nutrient requirements for growth and maintenance of intestinal health. In particular, this article reviews the role of specific amino acids (arginine, glutamine, glutamate, and threonine), fatty acids (long chain polyunsaturated, medium chain, and short chain), various prebiotic carbohydrates (short-chain fructo-oligosaccharide, fructo--oligosaccharide, lacto-N-neotetraose, human milk oligosaccharide, polydextrose, and galacto-oligosaccharide), and probiotics that have been examined in the suckling piglet model of intestinal health.

Nitrogen Requirements for Vegetative Growth, Flowering, Seed Production, and Ramet Growth of Paphiopedilum armeniacum (Orchid)

Paphiopedilum armeniacum S. C. Chen et F. Y. Liu is endemic to China and has great ornamental value. Little is known about its nutrient requirement for growth and reproduction after deflasking (transplantation of seedlings from culture vessels to pots). We studied the effects of adding nitrogen (N) (0, 105, 210, and 420 mg·L−1) on the vegetative growth and reproduction of P. armeniacum. N enrichment improved leaf area and lengthened the leaf lifespan during the vegetative stage. The effects of N application on flower size were minor. The intermediate N level of 210 mg·L−1 (MN) increased the seed capsule weight, seed germination rate, and improved the growth of seedlings that developed from seeds of MN-treated plants. N fertilizer exerted little influence on ramet emergence and ramet number per plant, but a low N concentration of 105 mg·L−1 promoted the leaf number and leaf area of ramets. Appropriate N levels for P. armeniacum in production and cultivation should be determined according to different production objectives.

Grazer interactions with four species of Lyngbya in southeast Florida

Blooms of the toxic cyanobacteria Lyngbya spp. have been increasing in frequency and severity in southeast Florida in recent years. Lyngbya produces many active secondary metabolites which often act as feeding deterrents to generalist herbivores, possibly increasing the longevity of these nuisance blooms. Whilst diverse arrays of small invertebrate consumers are often found in association with Lyngbya, little is known of their grazing selectivity among species of Lyngbya. This study examines the feeding preference of grazers for four local Lyngbya species ( Lyngbya majuscula, Lyngbya confervoides, Lyngbya polychroa and Lyngbya spp.). Stylocheilus striatus and Haminoea antillarum showed no dietary selectivity between L. polychroa, L. majuscula and Lyngbya spp. in multiple choice feeding assays, whereas Bulla striata showed a distinct preference for L. polychroa ( P < 0.001). To determine whether preference might be related to species-specific secondary metabolites, L. majuscula, L. confervoides and L. polychroa non-polar and polar extracts were incorporated into artificial diets and offered to a range of mesograzers. No significant difference was noted in feeding stimulation or deterrence amongst extracts and the controls for any of the grazers. When fed a monospecific diet of L. polychroa, S. striatus consumed more ( P < 0.001) and attained a higher daily biomass ( P = 0.004) than S. striatus fed L. confervoides. As L. polychroa and L. confervoides often co-exist on local coral reefs and yield dense numbers of S. striatus, host switching to a more palatable species of Lyngbya may have important implications regarding top-down control of local blooms leading to proliferation of one species and decimation of another. S. striatus fed a diet of L. polychroa consumed more ( P = 0.003), had a greater increase in body mass ( P = 0.020) and higher conversion efficiency ( P = 0.005) than those fed L. confervoides regardless of host origin. Possible explanations for host switching between species of Lyngbya related to morphology, toxicity and nutrient requirements for growth are discussed.

Symposium Paper: Pre-Calving Nutrition and Management Programs for Two-Year-Old Beef Cows

AbstractA female replacement program is needed in beef production enterprises to replace cows that have been culled for various reasons. Replacement females may come from either internal or external sources. Regardless of the source, management and nutrition play a large role in the successful development of these replacement females. In either case, females must be grown, mated, calved, and re-mated to enter the cow herd successfully. In most production systems in the US and Canada, replacement females are mated to calve at 2yr of age. These females have not yet reached their mature BW (MBW) at first calving. Consequently, higher nutritional and management demands are placed on these females following first calving. In addition to nutrient requirements for maintenance, lactation, and reproduction, these females also have nutrient requirements for growth. It is generally accepted, based on numerous research trials and production observations, that pre-calving nutrition [which is fundamentally reflected in body condition score (BCS) at calving] has a major impact of the length of the postpartum anestrous period. Recent and on-going research has identified potential opportunities to positively manipulate physiological processes in young cows through feeding elevated undegradable intake protein (UIP) or gluconeogenic precursors. Studies in animal behavior related to grazing and foraging indicate that opportunities and interactions for improved nutritional status exist by incorporating principles of animal learning and behavior into heifer development programs. Low-cost strategies designed to meet the nutritional demands of young cows and management programs designed to optimize reproductive performance will facilitate successful replacement programs.

Effects of a Simulated Martian UV Flux on the Cyanobacterium, Chroococcidiopsis sp. 029

Dried monolayers of Chroococcidiopsis sp. 029, a desiccation-tolerant, endolithic cyanobacterium, were exposed to a simulated martian-surface UV and visible light flux, which may also approximate to the worst-case scenario for the Archean Earth. After 5 min, there was a 99% loss of cell viability, and there were no survivors after 30 min. However, this survival was approximately 10 times higher than that previously reported for Bacillus subtilis. We show that under 1 mm of rock, Chroococcidiopsis sp. could survive (and potentially grow) under the high martian UV flux if water and nutrient requirements for growth were met. In isolated cells, phycobilisomes and esterases remained intact hours after viability was lost. Esterase activity was reduced by 99% after a 1-h exposure, while 99% loss of autofluorescence required a 4-h exposure. However, cell morphology was not changed, and DNA was still detectable by 4',6-diamidino-2-phenylindole staining after an 8-h exposure (equivalent to approximately 1 day on Mars at the equator). Under 1 mm of simulant martian soil or gneiss, the effect of UV radiation could not be detected on esterase activity or autofluorescence after 4 h. These results show that under the intense martian UV flux the morphological signatures of life can persist even after viability, enzymatic activity, and pigmentation have been destroyed. Finally, the global dispersal of viable, isolated cells of even this desiccation-tolerant, ionizing-radiation-resistant microorganism on Mars is unlikely as they are killed quickly by unattenuated UV radiation when in a desiccated state. These findings have implications for the survival of diverse microbial contaminants dispersed during the course of human exploratory class missions on the surface of Mars.

GROWING MANGO UNDER ORGANIC SYSTEM

Organic farming largely excludes the use of synthetic farm chemicals which are replaced with organic inputs and biologically active formulations. In order to market any produce as organic, certification is necessary from competent authorities, taking into consideration the system of raising the crop. Hence organic is a process claim than a product claim. Mango appears to be amenable for organic farming. Perennial fruit crops with their large framework and huge dry matter built-up over the years, meet a large part of their current nutrient requirements for growth and development through internal mobilization of vast reserve of nutrients. Mango being a perennial fruit crop with a large framework seems even less dependent on chemical fertilizers than many other fruit crops and its current nutrient requirement can be met by recycling of its plant residues by vermiculture, organic manures and biofertilizers. Biological control methods for managing some pests and diseases are available. Chemical-free postharvest treatments are in vogue in mango. However, more location-specific research efforts would be required on some of these aspects in order to achieve sustainable high yields.

Measuring energy expenditure in preterm and unstable infants

Measuring energy expenditure in preterm and unstable infants

Response of weaned pigs to choice feeding of a complete diet

Choice feeding of complete feeds offers the potential for a more gradual transition to feeds of lower specification as the pig grows. This may result in more efficient production as the pig consumes a blend of nutrients which provides the optimum match to its nutrient requirement for growth. The objective of this study was to compare performance of weaned pigs fed a sequence of commercial feeds with pigs allowed consume these diets free choice.Two experiments were carried out using pigs weaned at 22-26 days of age, penned in groups of 16 and fed the test diets for a 26 day period from weaning. The test diets were commercial starter, link and weaner feeds, marketed as suitable for pigs of 3-8kg, 8-15kg and 15-30kg respectively. Each group had two self feeders, 0.75m long with one diet in each. After the 26 day trial period all pigs received a common grower diet (barley, wheat, soyabean meal, fishmeal, DE: 14.4 MJ/kg, lysine: 1.19%) to about 36kg liveweight

Response of weaned pigs to choice feeding of a complete diet

Choice feeding of complete feeds offers the potential for a more gradual transition to feeds of lower specification as the pig grows. This may result in more efficient production as the pig consumes a blend of nutrients which provides the optimum match to its nutrient requirement for growth. The objective of this study was to compare performance of weaned pigs fed a sequence of commercial feeds with pigs allowed consume these diets free choice.Two experiments were carried out using pigs weaned at 22-26 days of age, penned in groups of 16 and fed the test diets for a 26 day period from weaning. The test diets were commercial starter, link and weaner feeds, marketed as suitable for pigs of 3-8kg, 8-15kg and 15-30kg respectively. Each group had two self feeders, 0.75m long with one diet in each. After the 26 day trial period all pigs received a common grower diet (barley, wheat, soyabean meal, fishmeal, DE: 14.4 MJ/kg, lysine: 1.19%) to about 36kg liveweight

In vitro growth and microcycle conidiation of Idriella bolleyi, a biocontrol agent of cereal pathogens

The minimum nutrient requirements for growth of Idriella (= Microdochium ) bolleyi in shaken liquid culture were mineral salts, nitrate nitrogen, glucose and thiamine. Typical batch culture kinetics were displayed in this medium and were assessed by culture turbidity when sodium alginate was used to induce growth by dispersed mycelia. Conidia were produced during exponential growth and reached maximum numbers ( ca 6 × 10 7 ml −1 ) by the deceleration or early stationary phase. Applying the Monod equation to culture parameters at different glucose concentrations, the minimum doubling time in glucose-nitrate-thiamine medium at 25 °C was calculated as between 5·25 and 6·1 h, and K s (limiting substrate concentration at half maximum specific growth rate) was between 0·049 and 0·077% glucose. Conidial germination was oxygen-dependent but did not require nutrients. On water agar or 0·1% glucose agar most spores germinated by germ-tubes, but up to 15% of spores swelled and produced further conidia (2–5) from one or both poles of the parent spore. This microcycle conidiation was suppressed at higher glucose levels. The findings are discussed in relation to production of biocontrol inocula and efficiency of I. bolleyi in biocontrol on roots.

Body Composition of Cats as a Basis for Factorial Calculation of Energy and Nutrient Requirements for Growth

Body Composition of Cats as a Basis for Factorial Calculation of Energy and Nutrient Requirements for Growth

A Rumen Linear Programming Model for Evaluation of Concepts of Rumen Microbial Function

A linear programming model provides for analysis of general input-output relationships in the rumen, for evaluation of competitive relationships among rumen microbes, and for computation of optimal relationships in the rumen. Eight rumen microbial groups defined on the bases of substrate specificity, nutrient requirements for growth, fermentation products, and relative metabolic activities comprise the central core of the model. Relative metabolic rates of microbial groups calculated from their cell sizes were used as coefficients in the objective function. The model was used to evaluate effects of different amounts of protein from feed and various carbohydrates upon microbial population and fermentation patterns as accommodated by current concepts. During the several solutions of the model, considerable simplification of the rumen microflora occurred. This implies that current data and concepts, and the hypothesis regarding relative metabolic rate, as represented in the model, do not accommodate adequately competitions among the several rumen microbial species and, thus, that additional data and concepts regarding rumen microbial interactions are required. Also evaluated were effects of ingestion of bacteria by protozoa upon over-all rumen function, absolute microbial cell yields, cell yields per mole of adenosine triphosphate, and factors affecting these.

The Effect of Thyroprotein on Growth Rate of Dwarf Pullets

Interest has been growing recently in the use of dwarf pullets for commercial egg production. Such interest stems from the possible saving in feed and housing costs due to the small body size of this bird. The adult body weight of the dwarf is approximately two-thirds that of today’s normal egg production pullet even though the hatching weights of both are the same. Comparatively little work has been done concerning the nutrient requirements for growth and egg production of the dwarf birds. However, from the work that has been reported by Bernier and Arscott (1966) and Arscott and Bernier (1968), it is evident that they consume much less feed, and egg production and egg size are significantly lower than that of normal hens. A study in our laboratory has confirmed the work of the above authors with regards to low egg production and small egg size and attempts to improve…