Feeding Policy Research Articles

Persistence and productivity of perennial ryegrass in sheep pastures in south-western Victoria: a review

Loss of perennial ryegrass (Lolium perenne L.) from the pasture within several years of sowing is a common problem in the higher rainfall (550–750 mm annual rainfall), summer-dry regions of south-eastern Australia. This pasture grass came to Australia from northern Europe, where it mostly grows from spring to autumn under mild climatic conditions. In contrast, the summers are generally much drier and hotter in this region of south-eastern Australia. This ‘mismatch’ between genotype and environment may be the fundamental reason for the poor persistence. There is hope that the recently released cultivars, Fitzroy and Avalon, selected and developed from naturalised ryegrass pastures in south-eastern Australia for improved winter growth and persistence will improve the performance of perennial ryegrass in the region. Soon-to-be released cultivars, developed from Mediterranean germplasm, may also bridge the climatic gap between where perennial ryegrass originated and where it is grown in south-eastern Australia. Other factors that influence perennial ryegrass persistence and productivity can be managed to some extent by the landholder. Nutrient status of the soil is important since perennial ryegrass performance improves relative to many other pasture species with increasing nitrogen and phosphorus supply. It appears that high soil exchangeable aluminium levels are also reducing ryegrass performance in parts of the region. The use of lime may resolve problems with high aluminium levels. Weeds that compete with perennial ryegrass become prevalent where bare patches occur in the pasture; they have the opportunity to invade pastures at the opening rains each year. Maintaining some herbage cover over summer and autumn should reduce weed establishment. Diseases of ryegrass are best managed by using resistant cultivars. Insect pests may be best managed by understanding and monitoring their biology to ensure timely application of pesticides and by manipulating herbage mass to alter feed sources and habitat. Grazing management has potential to improve perennial ryegrass performance as frequency and intensity of defoliation affect dry matter production and have been linked to ryegrass persistence, particularly under moisture deficit and high temperature stress. There is some disagreement as to the merit of rotational stocking with sheep, since the results of grazing experiments vary markedly depending on the rotational strategy used, climate, timing of the opening rains, stock class and supplementary feeding policy. We conclude that flexibility of grazing management strategies is important. These strategies should be able to be varied during the year depending on climatic conditions, herbage mass, and plant physiology and stock requirements. Two grazing strategies that show potential are a short rest from grazing the pasture at the opening rains until the pasture has gained some leaf area, in years when the opening rains are late. The second strategy is to allow ryegrass to flower late in the season, preventing new vegetative growth, and perhaps allowing for tiller buds to be preserved in a dormant state over the summer. An extension of this strategy would be to delay grazing until after the ryegrass seed heads have matured and seed has shed from the inflorescences. This has the potential to increase ryegrass density in the following growing season from seedling recruitment. A number of research opportunities have been identified from this review for improving ryegrass persistence. One area would be to investigate the potential for using grazing management to allow late development of ryegrass seed heads to preserve tiller buds in a dormant state over the summer. Another option is to investigate the potential, and subsequently develop grazing procedures, to allow seed maturation and recruitment of ryegrass seedlings after the autumn rains.

Effect of simple and complex carbon sources, low temperature culture and complex carbon feeding policies on poly-3-hydroxybutyric acid (PHB) content and molecular weight (M w ) from Azotobacter chroococcum 6B

The molecular weight (M w) of poly-3-hydroxybutyrate (PHB), produced by shake-flask culture of Azotobacter chroococcum showed little variation with increasing glucose concentration as carbon source (being in the range of 400–500 kDa), while M w increased from 300–400 to 640 kDa when grown with increasing concentration of sugar cane molasses. Molecular weight increased nearly 30% from 48 to 72 h culture time when 5% molasses as carbon source was used, while with glucose the highest M w was reached at 48 h. Under fermentor cultivation A. chroococcum produced PHB with a relatively high M w of 1590 kDa at 53 h culture time when grown in modified Burk's medium with glucose as carbon source at an initial C/N ratio (molar basis) of 69 under fermentor cultivation. A batch glucose-grown ammonium-limited fermentor culture was repeatedly fed with sugar cane molasses (initial C/N ratio 69) and it was observed that PHB content curve decreased at a slower rate than in the fed-batch culture in which glucose and sucrose were not consumed in the culture medium after the feed.

High food wastage and low nutritional intakes in hospital patients

Background and Aims: The aim of this study was to investigate the cause of continuing weight-loss in hospitalized patients. We determined 1. whether the hospital menu was able to meet the patients' minimum nutritional requirements, 2. the proportion of food being wasted and 3. the mean nutritional intakes of patients.Methods: This study was carried out in a University hospital (1200 beds). All the food supplied and wasted was measured over a 28 day period on one ward in each of 4 different specialities. Average food intake per patient was calculated and checked against individual food intake measurements.Results: The hospital menu provided over 2000 kcal/day and could meet patients' nutritional requirements. However, high wastage rates of greater than 40% resulted in energy and protein intakes within all specialities being less than 80% of that recommended. The cost of this waste was £139,655 in these four specialities.Conclusions: More than 40% of hospital food was wasted. Energy and protein intakes were low and patients did not, therefore, meet their recommended intakes. This helps to explain continuing weight-loss in hospital patients and represents a large waste of resources. Hospital feeding policies therefore need reviewing and made more appropriate to the needs of the sick.

Influence of infant feeding patterns on early mother-to-child transmission of HIV-1 in Durban, South Africa.

Previous studies on the effect of breastfeeding on mother-to-child transmission (MTCT) of HIV have not attempted to examine the influence of different types of breastfeeding practice. To attempt to address some of these inadequacies, infant feeding practices of 549 HIV-infected women involved in a trial in Durban, South Africa were documented prospectively. Women were counseled on infant feeding choices according to UNAIDS guidelines, and those who chose to breastfeed were encouraged to practice exclusive breastfeeding. The MTCT rates of HIV-1 at 3 months were compared in the three different feeding groups (never breastfed, exclusive breastfeeding, and mixed breastfeeding). At 3 months, 18.8% of 156 never-breastfed children were infected compared to 21.3% of 393 breastfed children (p = 0.50). Children exclusively breastfed to at least 3 months (n = 103) were less likely to be infected (14.3%) than those receiving mixed feeding before 3 months (24.1%) (p = 0.03). After adjustment for potential confounders (maternal CD4:CD8 ratio, syphilis screening test results, and preterm delivery), exclusive breastfeeding carried a significantly lower risk of HIV-1 transmission than mixed feeding (hazard ratio [HR] 0.52, 95% CI: 0.28-0.98) and an equivalent risk to no breastfeeding (HR 0.85, 95% CI: 0.51-1.42). Our findings have important implications for HIV and infant feeding policies in developing countries, and it is critical that further research be undertaken. In the meantime, breastfeeding policies for HIV-infected women require urgent review. If confirmed, exclusive breastfeeding may offer HIV-infected women in developing countries an affordable, culturally acceptable, and effective means of reducing MTCT of HIV-1 while maintaining the overwhelming benefits of breastfeeding.

Caries and its association with infant feeding and oral health-related behaviours in 3-4-year-old Brazilian children.

To investigate the relationships between socio-demographic factors, infant feeding habits, oral hygiene and the prevalence and patterns of caries in Brazilian 3-4-year-olds. Systematic random sampling was used to select children enrolled in municipal nurseries in Araraquara, Brazil, in 1998. Clinical examinations were carried out by one examiner using dmft and dmfs indices and WHO criteria. Questionnaires for information related to the socio-demographic background, oral hygiene and dietary history of the children were completed by their mothers. Caries was seen in 46% of the children; 17% of them had the more extensive pattern involving molars and incisors. Social class, mother's education, and age at which breast-feeding terminated showed statistically significant associations with caries. Feeding bottles with added sugars were still being given to 80% of the children. When the significant variables were taken into account only age at which breast-feeding terminated showed a significant relationship to the pattern of disease. Children who were never breast-fed or were breast-fed beyond the age of 24 months had a higher prevalence of the more extensive pattern of caries. The association between the length of time a mother breast-feeds and extensive caries should be a consideration in any local infant feeding policies or health promotion strategies. The duration for appropriate breast- or bottle-feeding should be emphasised.

Dynamic modeling and optimal fed-batch feeding strategies for a two-phase partitioning bioreactor.

A dynamic model for the degradation of phenol in a two-phase partitioning bioreactor has been developed based on mechanistic balances around the bioreactor. The key process characteristics including substrate transfer between the organic and aqueous phases, substrate inhibition, oxygen limitation, and cell entrainment were incorporated into the model. The model predictions were validated against existing experimental data obtained for a 2-L bioreactor, and good correlation was observed for the time frames of the simulations, as well as for trends in cell and substrate concentrations. Optimal fed-batch, phenol feeding strategies were then developed based on two approaches: (1) maximization of phenol consumption in a fixed time interval and (2) consumption of a fixed amount of phenol in minimal time. The optimal feeding policies, determined using the Iterative Dynamic Programming algorithm, provided substantial improvements in the amount of phenol consumed when compared to a typical experimental heuristic approach. For example, 45.73 g of phenol was predicted to be consumed in 50 h (not including lag phase) using the optimal feeding profile compared to 10.26 g of phenol consumed in the simulated experimental approach. Oxygen limitation was predicted to be a recurring operational challenge in the partitioning bioreactor, and had a strong impact on the optimization results.

Nutrition after stroke.

Decisions about feeding are amongst the most difficult to face those managing stroke patients. About a fifth of patients with acute stroke are malnourished on admission to hospital. Moreover, patients' nutritional status often deteriorates thereafter because of increased metabolic demands which cannot be met due to feeding difficulties. Poor nutritional intake may result from: (i) reduced conscious level; (ii) an unsafe swallow (iii) arm or facial weakness; (iv) poor mobility; or (v) ill fitting dentures. Malnutrition is associated with poorer survival and functional outcomes, although these associations may not be causal. Patients often receive support with oral supplements or enteral tube feeding via nasogastric or percutaneous endoscopic gastrostomy. Although these probably improve nutritional parameters, it is unclear whether they improve patients' outcomes. Also the optimal timing, type and method of enteral feeding is uncertain. Large randomised trials are now in progress to identify the optimum feeding policies for stroke patients.

Breastfeeding duration and current neonatal feeding practices in Emilia Romagna, Italy

A cohort of 1567 infants was studied at birth and at 3 mo of age to elucidate factors possibly affecting feeding policies in the maternity ward and the relationship with subsequent feeding patterns. During their stay in the maternity wards 89.6% of infants were breastfed, with 28.1% receiving formula in addition to mother's milk. Independent predictors of receiving a formula supplement in the maternity wards as a result of multivariate analyses were the separation of the newborn from the mother, a birthweight lower than 3000 g and a gestational age lower than 38 wk. At 3 mo of age, 66.1% infants were still at least partially breastfed and 48.9% were exclusively breastfed. An increased risk of not being breastfed at 3 mo of age was related to supplementary feeding at birth and birthweight. A weak relationship was found between the prevalence of breastfeeding at 3 mo of age and the magnitude of routine formula supplement use in the maternity ward. Given the present trends for early discharge from maternity wards and the National Health System facility for free paediatric assistance after discharge, in Italy paediatricians should be the main actors to support the continuation of breastfeeding.

A survey of feeding practices in infants with phenylketonuria

Summary Background: Although the management of phenylketonuria (PKU) in infancy and early childhood is a critical part of the overall care of the disorder, there are few guidelines on infant feeding in this condition. This survey was undertaken to establish the practices of dietitians from major PKU centres in Australia and the UK. Methods: A postal questionnaire examining infant feeding practices was sent to dietitians at nine major PKU centres in the UK and four in Australia, with each dietitian describing the infant feeding process in their last five infants. A total of 63 infants were investigated. Results: A lower than expected incidence of infants with PKU were breast fed at the time of diagnosis: 28% of infants in the UK and 41% from Australia. Amino acid intake varied between 2.0 g kg−1 day−1 to 3.5 g kg−1 day−1 with 86% of dietitians calculating total amino acid intake derived from both protein substitute intake and normal infant formula. Amino acid intake was not calculated in breast‐fed infants. In breast‐fed infants, phenylalanine‐free protein substitute was always given before breast feeds. In bottle‐fed infants, normal infant formula was given before phenylalanine‐free protein substitute in 75% of infants. Solids were usually introduced between 3 and 6 months and phenylalanine‐free solids were given initially to the majority of infants. Most problems were seen when introducing a more concentrated phenylalanine‐free protein substitute to maintain the required amino acid intake in older infants. Age of introduction varied between 4 and 12 months and type of approach included concentrating infant protein substitutes, use of L‐amino acid protein substitutes only, or L‐amino acid protein substitutes with added carbohydrate, vitamins and minerals. Conclusions: There appeared to be no uniform policy of infant feeding in PKU and more work is needed correlating practices to develop national and even international protocols for management.

Preparation and characterization of MMA-BA-DMAEMA terpolymer latex

The terpolymer latex of methyl methacrylate (MMA)/butyl acrylate (BA)/dimethylaminoethyl methacrylate (DMAEMA) was prepared by batch and semi-continuous emulsion copolymerization. The effects of emulsifier type and concentration, polymerization temperature, and feed policy of emulsified monomers on process stability of the copolymerization and properties of the terpolymer latex were studied systematically. The results suggest that the selection of emulsifier should not be based on the HLB values for the DMAEMA-containing systems. The co-emulsifiers suitable for stabilizing the copolymerization process are in the order of SDS/OP>SDBS/OP>OT/OP. The results also indicate that an increase in amount of the co-emulsifiers, sodium dodecyl sulfate (SDS) and octyl phenol polyoxyethyl ether (OP), improves the process stability, decreases the surface tension and particle size of latices; however, it has little influence on the electrolyte stability when SDS/OP ratio is unchanged. A decrease in reaction temperature improves the process stability of polymerization but decreases the electrolyte stability of latices. The DMAEMA content does not affect the process stability significantly under investigated conditions but contributes to improve the electrolyte stability of latices. Compared to the batch polymerization process, the semi-continuous polymerization with a lower monomer feed rate provides better process stability for the polymerization and better electrolyte stability for the latices.

Characterization and comparison of biomasses from single- and multi-fed upflow anaerobic filters

Two lab-scale single-fed (SFR) and multi-fed (MFR) upflow anaerobic filters treating a cheese whey wastewater were operated at Organic Loading Rates (OLR) higher than 20 kg COD/m 3/d. The occluded and attached biomass values and the hydrolytic, acidogenic and methanogenic activities of sludges at different heights were determined in the filters. The feeding policy affected both biomass concentration (attached and occluded) and activity. Although a lower amount of biomass was retained in the MFR, the distribution along the filter was more homogeneous than in the SFR. The specific activities of the different trophic groups were higher in the MFR. Because of both facts, the methanogenic capacity of the MFR was higher than that in the SFR, this resulting in a more efficient operation, especially when operated at the highest OLR.

Improved stability and expression of a recombinant shuttle plasmid in Escherichia coli during fedbatch cultivation

The effect of higher cell densities on the expression and segregational stability of a recombinant E. coli- B. subtilisshuttle plasmid coding for carboxymethylcellulase (CMCase) activity, was studied in E. coli DH5α. Of the various feeding policies adopted for maximal expression and stability, exponential feeding resulted in the highest biomass of 15g dry cell weight (DCW) l−1 and plasmid stability of 45%. A CMCase activity of 11400 Uml−1 was achieved as compared to 230 Uml−1 during batch cultivation. In the case of other feeding strategies viz., constant feeding, linear feeding or intermittent feeding, the plasmid stability varied between 20% to 60%. Biomass achieved ranged from 5.0 g DCW l−1 to 9.0 g DCW l−1 and enzyme activities were between 2550 Uml−1 and 6000 Uml−1.

Breastfeeding

While Marie Biancuzzo’s guest editorial, “Breastfeeding: Making It Happen at Home” (July/August 1998 JOGNN) is informative, we believe that its identification of infant formula marketing practices as the “most notable barrier” to breastfeeding initiation and continuation in the United States is inconsistent with published research reports. Although several clinical trials have examined the link between distribution of hospital discharge packs and shortened duration of breastfeeding, this relationship remains inconclusive ( Bliss et al., 1997 Bliss M.C. Wilkie J. Acredolo C. Berman S. Tebb K.P. The effect of discharge pack formula and breast pumps on breastfeeding duration and choice of infant feeding method. Birth. 1997; 24: 90-97 Crossref PubMed Google Scholar ; Feinstein et al., 1986 Feinstein J.M. Berkelhamer J.E. Gruszka M.E. Wong C.A. Carey A.E. Factors related to early termination of breastfeeding in an urban population. Pediatrics. 1986; 78: 210-215 PubMed Google Scholar , Frank et al., 1987 Frank D.A. Wirtz S.J. Sorenson J.R. Heeren T. Commercial discharge packs and breastfeeding counseling: Effects on infant feeding practices in a randomized trial. Pediatrics. 1987; 78: 845-854 Google Scholar ; Howard and Howard, 1997 Howard C. Howard F.M. Commentary: Discharge packs: How much do they matter?. Birth. 1997; 24: 98-101 Crossref PubMed Scopus (2) Google Scholar ; Perez-Escamilla et al., 1994 Perez-Escamilla, R., Pollitt, E., Lonnerdal, B., & Dewey, K.G. Infant feeding policies in maternity wards and their effect on breast-feeding success: An analytic overview. American Journal of Public Health, 84, 89-97. Google Scholar ). This finding does not mean that we need to accept, condone, or participate in these marketing practices. Instead, the data suggest that we should not become so focused on policy about formula marketing that we fail to address the research-based barriers to breastfeeding that make women vulnerable to these marketing practices in the first place.

Strategies for the continuous production of ligninolytic enzymes in fixed and fluidised bed bioreactors

Production of ligninolytic enzymes by white-rot fungi is a phenomenon typically associated to the secondary metabolism, the main drawback of which is the limited yield of the enzyme obtained under growth-limiting conditions and the morphological behaviour of these filamentous microorganisms while growing. An efficient production system is needed for the promising applications of these enzymes in bioprocesses such as detoxification of effluents and biobleaching of kraft pulp. Several bioreactor configurations were considered which were operated in batch or semi-continuous modes. These operational conditions permitted high titres of enzymatic activity, however, the extent of production was limited. A different modus operandi is then to be proposed to overcome these limitations. The present work reviews the state of production of ligninolytic enzymes and proposes a new method to achieve continuous production of manganese peroxidase (MnP). The method comprises a feeding policy based on controlled feed rates of nutrients and the use of an adequate bioreactor configuration. They were both key factors to attain and sustain continuous production of MnP. The feeding of limited concentrations of nutrients kept secondary metabolism in steady-state conditions and limited the fungal growth. The configuration of two conventional bioreactors (fluidised bed and fixed bed bioreactors) was modified with the introduction of pulsation of gas. Pulsation proved to be a good alternative to enhance nutrients and oxygen transfer as well as to maintain fungal cultures as independent bioparticles both for pellets and foam blocks of mycelia. Other environmental factors such as a Mn 2+ concentration of 5 mM and high oxygen tension enhanced MnP production. The hydraulics of the bioreactor also had effect on MnP production, the optimum corresponded to a plug flow model with partial mixing and an operating HRT of 24 h. This policy facilitated long operation periods, obtaining higher productivity rates than the best reported to date.

Fuzzy-Decision-Making Problems of Fuel Ethanol Production Using a Genetically Engineered Yeast

A fuzzy-decision-making procedure is applied to find the optimal feed policy of a fed-batch fermentation process for fuel ethanol production using a genetically engineered Saccharomyces yeast 1400 (pLNH33). The policy consisted of feed flow rate, feed concentration, and fermentation time. The recombinant yeast 1400 (pLNH33) can utilize glucose and xylose simultaneously to produce ethanol. However, the parent yeast utilizes glucose only. A partially selective model is used to describe the kinetic behavior of the process. In this study, this partially selective fermentation process is formulated as a general multiple-objective optimal control problem. By using an assigned membership function for each of the objectives, the general multiple-objective optimization problem can be converted into a maximizing decision problem. In order to obtain a global solution, a hybrid method of differential evolution is introduced to solve the maximizing decision problem. A simple guideline is introduced in the interactive programming procedures to find a satisfactory solution to the general multiple-objective optimization problem.

Modal analysis and optimization of isothermal autocatalytic reactions

A comprehensive and systematic analysis of optimization of autocatalytic reactions is presented in this article considering a very general objective function. The objective functions of common interest, such as maximum yield, maximum selectivity, maximum productivity and minimal reaction time, are some of the special cases of this general objective function. The following reaction scheme is considered in this work: A+ nB ⇌ ( n+1)B, A ⇌ B, B→C. The problem of maximization of the general objective function is posed as that of the optimal control of a variable-volume reactor with time-variant feed and effluent flow rates as the control variables. The systematic ‘modal’ analysis enables identification of feasible modes of reactor operation and conditions under which each feasible mode is admissible. Of all the possible modes, only a few are proved to be feasible and only certain transitions are permissible from each feasible mode. The policy for programmed manipulation of the feed and effluent flow rates is obtained employing the optimal control theory. Candidate optimal policies are identified as individual feasible modes or certain sequences of these. A singular fed-batch operation in which the feed rate is decided exclusively by the state of the reactor is part of some of the candidate optimal policies. Conditions for admissibility and feasibility of singular control and the feeding policy during singular control interval are obtained analytically for arbitrary kinetics of these reactions. The concentration trajectories in a fed-batch operation converge to or diverge from one or more limit points. Operation at each limit point is characterized by invariance of concentrations of all species, the feed rate being an exponential function of time. A linearized stability analysis, supported by numerical illustrations, reveals that some or all of the limit points may be accessible during fed-batch operation. The optimal operation strategy is linked to the disposition of batch reactor trajectories in the space of concentration variables. The rich behavioral patterns of autocatalytic reactions are revealed by specific numerical illustrations.

Current feeding policies for patients with stroke.

It is well known that policies for feeding patients who have suffered a recent stroke vary enormously. The choice of method used may depend on the severity of the stroke, i.e. swallowing ability, conscious level, ability to communicate and the level of sensory and motor dysfunction. Other considerations may include age and previous nutritional status. However, in the absence of evidence from controlled clinical trials, the preferences of individual physicians and nurses may have a significant influence. As part of the preparatory work before the start of a clinical trial of different feeding policies, the author wished to assess both the degree of variability of feeding practice on wards in the same hospital and also whether there were reasons other than lack of evidence which influenced feeding policies. One nurse from each of 19 wards (one neurology, nine medical and nine care of the elderly) in two hospitals of the same trust was interviewed to ascertain their current feeding practice for patients with stroke. The results showed the expected variability in feeding practice, possibly reflecting the uncertainties felt by physicians and nurses in this area. However, many comments revealed the concerns that nurses have in trying to meet the nutritional needs of their stroke patients in busy acute general hospitals.

Food (Feed or Ordinary Diet) a Multicentre International Randomised Trial Evaluating Feeding Policies for Patients Hospitalised with a Recent Stroke: Introducing the Concept of a "Family" of trials

Food (Feed or Ordinary Diet) a Multicentre International Randomised Trial Evaluating Feeding Policies for Patients Hospitalised with a Recent Stroke: Introducing the Concept of a "Family" of trials

Optimization of fed-batch bioreactor using neural network model

An algorithm using feedforward neural network model for determining optimal substrate feeding policies for fed-batch fermentation process is presented in this work. The algorithm involves developing the neural network model of the process using the sampled data. The trained neural network model in turn is used for optimization purposes. The advantages of this technique is that optimization can be achieved without detailed kinetic model of the process and the computation of gradient of objective function with respect to control variables is straightforward. The application of the technique is demonstrated with two examples, namely, production of secreted protein and invertase. The simulation results show that the discrete-time dynamics of fed-batch bioreactor can be satisfactorily approximated using a feedforward sigmoidal neural network. The optimal policies obtained with the neural network model agree reasonably well with the previously reported results.

APPLICATIONS OF COMPOSITION CONTROL TO THE STYRENE-BUTYL ACRYLATE EMULSION COPOLYMERIZATION

Three different operating modes to produce constant composition copolymers in emulsion are examined. Experimental data are presented with reference to the binary copolymerization of styrene and butyl acrylate. Firstly, combining a composition-conversion model with the on-line monitoring of conversion through densimetry, a semibatch monomer feed policy aimed to minimize the reaction time is discussed. Secondly, a batch, pseudo-azeotropic mode is analyzed. A constant composition polymer is obtained by properly adjusting the initial amount of water to take advantage of the different monomer solubilities in aqueous phase. Finally, a semibatch case is examined where limitations of maximum reaction rate are operative. Once more, the composition-conversion model is combined with a suitable on-line monitoring of conversion by measurements of the ultrasound velocity in the reacting system.