Improved Energy Balance Research Articles

Do favourable effects of increasing unsaturated fat intake on cardiovascular disease risk outweigh the potential adverse effect on body weight?

The major health complication of overweight and obesity is cardiovascular disease (CVD). Although dietary fat is often seen as major cause of obesity, there is no strong evidence that decreasing the dietary fat content as such, without actively improving energy balance, prevents weight gain. The limited and heterogeneous data from long-term randomized trials suggest that a 10% of energy higher fat intake results in equal or at the very most 3 kg larger body weights as compared with higher carbohydrate intake. The consequence of some possible weight gain for CVD risk should be balanced against effects of diet composition independent of body weight. There is strong and consistent evidence from metabolic and clinical studies that under isoenergetic conditions, diets high in unsaturated fat are more effective for reducing CVD risk than low-fat diets. A quantitative estimation of effects on risk factors indicates that even if increasing unsaturated fat intake at the expense of carbohydrates would produce some weight gain on the long-term, the net effect on CVD risk is probably beneficial.

Glucocorticoids exacerbate obesity and insulin resistance in neuron-specific proopiomelanocortin-deficient mice

Null mutations of the proopiomelanocortin gene (Pomc) cause obesity in humans and rodents, but the contributions of central versus pituitary POMC deficiency are not fully established. To elucidate these roles, we introduced a POMC transgene (Tg) that selectively restored peripheral melanocortin and corticosterone secretion in Pomc mice. Rather than improving energy balance, the genetic replacement of pituitary POMC in PomcTg mice aggravated their metabolic syndrome with increased caloric intake and feed efficiency, reduced oxygen consumption, increased subcutaneous, visceral, and hepatic fat, and severe insulin resistance. Pair-feeding of PomcTg mice to the daily intake of lean controls normalized their rate of weight gain but did not abolish obesity, indicating that hyperphagia is a major but not sole determinant of the phenotype. Replacement of corticosterone in the drinking water of Pomc mice recapitulated the hyperphagia, excess weight gain and fat accumulation, and hyperleptinemia characteristic of genetically rescued PomcTg mice. These data demonstrate that CNS POMC peptides play a critical role in energy homeostasis that is not substituted by peripheral POMC. Restoration of pituitary POMC expression to create a de facto neuronal POMC deficiency exacerbated the development of obesity, largely via glucocorticoid modulation of appetite, metabolism, and energy partitioning.

AAV-mediated leptin receptor installation improves energy balance and the reproductive status of obese female Koletsky rats

Leptin is a hormone secreted primarily by white adipocytes that regulates energy homeostasis and reproduction via CNS receptors. Koletsky ( f/ f) rats with a leptin receptor (OB-Rb) gene mutation are obese, diabetic and infertile. We employed recombinant adeno-associated viral (rAAV) vectors to transfer the human OB-Rb gene into the brains of female Koletsky rats to identify sites of leptin action in the brain. rAAV-OB-Rb was microinjected into the medial preoptic area (MPOA), the paraventricular nucleus (PVN), the ventromedial hypothalamus, the arcuate nucleus (ARC), or the dorsal vagal complex in the brainstem. Food intake and body weight were monitored bi-weekly for 55 days. Vaginal cytology was examined daily to assess estrous cyclicity. After sacrifice, uncoupling protein-1 (UCP-1) mRNA in brown adipose tissue and serum concentrations of leptin, insulin, glucose, estradiol and progesterone were measured. Expression of OB-Rb was documented by RT-PCR and site specificity of microinjection was verified by immunohistochemical detection of green fluorescent protein following a control microinjection of rAAV-GFP. OB-Rb installation in the ARC reduced food intake, however, energy expenditure, assessed by UCP-1 mRNA expression, was increased by OB-Rb installation in all sites except the PVN. When injected into the MPOA and ARC, rAAV-OB-Rb stimulated the reproductive axis as evidenced by normalization of estrous cycle length and increased luteinizing hormone releasing hormone concentrations in the hypothalamus. These studies show that long-term installation of a functional leptin receptor in the CNS is achievable using rAAV vectors and further show that leptin acts on specific sites in the brain to produce differential effects on food intake, energy expenditure and reproduction.

Adipocyte-Specific Glucocorticoid Inactivation Protects Against Diet-Induced Obesity

Local glucocorticoid (GC) action depends on intracellular GC metabolism by 11beta-hydroxysteroid dehydrogenases (11betaHSDs). 11betaHSD1 activates GCs, while 11betaHSD2 inactivates GCs. Adipocyte-specific amplification of GCs through transgenic overexpression of 11betaHSD1 produces visceral obesity and the metabolic syndrome in mice. To determine whether adipocyte-specific inactivation of GCs protects against this phenotype, we created a transgenic model in which human 11betaHSD2 is expressed under the control of the murine adipocyte fatty acid binding protein (aP2) promoter (aP2-h11betaHSD2). Transgenic mice have increased 11betaHSD2 expression and activity exclusively in adipose tissue, with the highest levels in subcutaneous adipose tissue, while systemic indexes of GC exposure are unchanged. Transgenic mice resist weight gain on high-fat diet due to reduced fat mass accumulation. This improved energy balance is associated with decreased food intake, increased energy expenditure, and improved glucose tolerance and insulin sensitivity. Adipose tissue gene expression in transgenic mice is characterized by decreased expression of leptin and resistin and increased expression of adiponectin, peroxisome proliferator-activated receptor gamma, and uncoupling protein 2. These data suggest that reduction of active GCs exclusively in adipose tissue is an important determinant of a favorable metabolic phenotype with respect to energy homeostasis and the metabolic syndrome.

Effects of Feeding Propionate and Calcium Salts of Long-Chain Fatty Acids on Transition Dairy Cow Performance

Multiparous Holstein cows (n=40) were used in a randomized complete block design to determine the effects of feeding Ca and Na salts (1:1, wt/wt) of propionate and Ca salts of long-chain fatty acids (LCFA) on transition cow performance. All cows were fed the same basal diet once daily for ad libitum intake. Treatments (g/d) were 320 cornstarch (CS) as a control, 120 propionate (PRO), 120 propionate and 93 LCFA (PF1), and 178 propionate and 154 LCFA (PF2). Treatments were hand-mixed into the upper one-third of the TMR from 2 wk pre- through 3 wk postpartum. Intakes were recorded from 21 d pre- through 21 d postpartum. Energy density and crude protein were 1.54 and 1.65 Mcal/kg and 14.4 and 18.8% for pre- and postpartum diets, respectively. All cows received a common diet from 22 to 70 days in milk (DIM). Milk composition was analyzed on d 7, 14, and 21. Blood was sampled at 14, 7, and 2 d prepartum and 2, 7, 14, and 21 DIM. Pre- and postpartal dry matter intake (DMI) averaged 11.9 and 16.4kg/d, respectively, and did not differ among treatments. A diet×week interaction for postpartal DMI was observed as cows fed PF2 consumed 2kg/d less DM during wk 2 relative to other treatments. Milk yields from 22 to 70 DIM were 48.8, 48.5, 47.8, and 51.3kg/d for CS, PRO, PF1, and PF2, respectively, and were not significantly affected by treatments. Milk true protein (3.32 vs. 3.16%) was increased and MUN (12.5 vs. 14.4mg/dL) was decreased for CS relative to other treatments. Milk fat yield from cows fed PRO tended to be greater than those fed PF1 (1.58 vs. 1.29kg/d). Plasma glucose, insulin, and β-hydroxybutyrate were not affected by treatments. The PF2 treatment tended to decrease NEFA in plasma relative to PF1 over all times measured (492 and 670μEq/L) and significantly decreased plasma NEFA relative to those fed PF1 postpartum (623 and 875μEq/L). Relative to PF1, feeding propionate and LCFA at the higher level in this experiment improved energy balance postpartum as evidenced by decreased concentrations of plasma NEFA.

Evaluation of Rumen-Protected Choline and Monensin Controlled-Release Capsule on Milk Production, Health and Metabolic Function of Periparturient Dairy Cows

During early lactation, dairy cows undergo a phase of negative energy balance which may lead to metabolic disorders and subsequent losses in production. To help reduce this, ionophores may be administered. Administration of monensin controlled-release capsules (CRC) prior to calving improves energy balance, while choline aids in fat metabolism and transport. Choline may be a limiting nutrient in lactating dairy cows. The objective of this study was to determine whether there is an interection between these two supplements on metabolic parameters and milk production.

Effect of Liquid Flavor Supplementation of the Diet on Dairy Cows in the Transition Period

A 9-wk trial was conducted to study the performance of 24 Holstein cows during the transition period (3wk prepartum to 6wk postpartum). Cows were assigned to either a control or liquid-flavored (0.52mL/kg of feed) total mixed ration in a randomized complete block design. The diets contained corn silage, alfalfa haylage, cottonseed, and a grain mix based on ground corn and soybean meal. Cows were fed to ensure 10% orts, and the diet provided (on a dry matter basis) 13% crude protein, 32% acid detergent fiber, 44% neutral detergent fiber, and 1.54Mcal/kg of NEL prepartum and 17.5% crude protein, 30% acid detergent fiber, 40% neutral detergent fiber, and 1.57Mcal/kg of NEL postpartum. An additional 2.3kg of alfalfa hay was fed during the first 5 d postpartum. Weekly means of dry matter intake (DMI), milk yield, milk protein, milk fat, SNF, somatic cell counts, and body weight (BW) were analyzed using a repeated measures procedure. There was no effect of treatment on these variables, and least squares means were 16.9 and 15.7kg/d for DMI, 38 and 35.3kg/d for milk yield, 3.10 and 3.11% for milk protein, 3.69 and 3.74% for milk fat, 8.37 and 8.16% for SNF, 1.99×105 and 4.33×105 for somatic cell count, and 631 and 651kg for BW for cows fed control and flavored diets, respectively. Individual cow daily DMI data were fitted to an exponential model describing pre- and postpartum feed consumption [DMI = a−b×e(−c×t), where DMI was measured in kg, a = asymptotic DMI, b = potential fractional increase in DMI, c = fractional rate of increase in DMI, and t = days prior to calving or days in milk]. Fractional rates of increase in DMI were similar: 0.139 and 0.123/d for control and flavored diets, respectively. Data for both groups were separately analyzed using multiple regression with 3.5% fat-corrected milk as the dependent variable and BW and DMI as independent variables. More BW was mobilized per unit increase in 3.5% fat-corrected milk in cows fed the control than in cows fed the flavored diet. Cows fed the control diet tended to be in more negative energy balance during early lactation than cows fed the flavored diet. It was concluded that feeding flavor improved energy balance of cows in early lactation and may reduce the risk of health or reproductive problems.

Palliative nutritional intervention in addition to cyclooxygenase and erythropoietin treatment for patients with malignant disease: Effects on survival, metabolism, and function

The role of nutrition in the palliative treatment of patients with malignancy-related cachexia is unclear. The goal of the current study was to determine whether specialized, nutrition-focused patient care could improve integrated whole-body metabolism and functional outcome in unselected weight-losing patients with malignant disease who were receiving systemic antiinflammatory (cyclooxygenase [COX]-inhibitory) treatment along with erythropoietin (EPO) support. Three hundred nine patients with malignant disease who experienced progressive cachexia due to solid tumors (primarily gastrointestinal lesions) were randomized to receive a COX inhibitor (indomethacin, 50 mg twice daily) and EPO (15-40,000 units per week) along with specialized, nutrition-focused patient care (oral nutritional support and home total parenteral nutrition [TPN]) provided on a patient-by-patient basis to attenuate inflammation, prevent anemia, and improve nutritional status. Control patients received the same indomethacin and EPO doses that study patients received without the added nutritional support. All patients were treated and followed until death. Biochemical assays (blood, liver, kidney, and thyroid), nutritional state assessment (food intake and body composition), and exercise testing with simultaneous measurement of whole-body respiratory gas exchange before and during exercise were performed before the start of treatment and then at regular intervals during the treatment period (every 2-30 months after treatment initiation). Statistical analyses were performed on 'intention-to-treat' and 'as-treated' bases. Home TPN was provided to approximately 50% of the study patients without severe complications. Over the entire observation period, rhEPO prevented the development of anemia in both study patients and control patients. Intention-to-treat analysis revealed an improvement in energy balance for nutritionally supported patients (P < 0.03); no other significant differences in outcome between study patients and control patients were observed. As-treated analysis demonstrated that patients receiving nutrition experienced prolonged survival (P < 0.01), which was accompanied by improved energy balance (P < 0.001), increasing body fat (P < 0.05), and a greater maximum exercise capacity (P < 0.04). A trend toward increased metabolic efficiency at maximum exercise (P < 0.06) for study patients relative to control patients also was observed. The results of the current study strongly support that nutrition is a limiting factor influencing survival and that nutritional support protects integrated metabolism and metabolic function in patients with progressive cachexia secondary to malignant disease.

Usefulness of ionophores for lactating dairy cows: a review

In recent years, ionophores (IOP) have been approved in several countries around the word for use in lactating dairy cows with claims for improved milk production and immune response. Currently, the use of IOP in lactating dairy cattle is not allowed in the USA, although the application for approval of monensin for use in these animals has been submitted. As a result, additional data from experiments in which IOP were administered to lactating dairy cattle have become available over the last few years. The objective of this paper is to review the current data regarding the effects of these compounds on milk production, health status, and reproductive performance of lactating dairy cows. In the rumen, IOP inhibit gram positive bacteria, which subsequently alter ruminal fermentation resulting in increased amounts of energy and N from feeds in forms usable by the cow. When administered at effective doses, IOP do not affect, or slightly decrease, feed intake by lactating cows. This effect combined with the IOP-mediated alterations in rumen fermentation increases the supply of nutrients, particularly propionate. As a result, the energy balance is improved, enhancing in turn milk production, efficiency of milk production, and immune response. The magnitude of these effects, however, appears to be determined by several factors, many of which are poorly understood. Based on available data, improved energy balance and its favorable effects on health and milk production would be primary benefits of administering IOP to lactating cows. Thus, periparturient dairy cows, particularly over-conditioned cows, may benefit the most from the use of IOP. However, the development of efficient implementation strategies that maximize the economic returns will depend on a better understanding of the effects of IOP on the metabolism, performance, and health of transition and lactating dairy cattle.

カラマツ林の熱収支に与える貯熱変化量の影響

Sum of sensible and latent heat fluxes measured by the eddy covariance technique is systematically smaller than available energy in many terrestrial ecosystems, which includes forests. This energy imbalance is an essential issue for the flux measurement. In this study, we evaluated heat storage flux and investigated its effect on energy balance in a larch plantation developing on a flat terrain. Above-ground biomass was the largest component producing the heat storage flux of the forest ecosystem; about 70-80% of the heat storage flux was generated in above-ground biomass for summer and fall. Moreover, the heat storage flux of topsoil over heat plates had a considerable bearing on the evaluation of soil heat flux. Adding these heat storage fluxes improved energy balance by 6-10%; it increased the slope of the ordinary least square between eddy energy fluxes and available energy, which was used as an index of energy balance closure, from 0.83 to 0.88 in summer and from 0.93 to 1.03 in fall. This suggests that we have to measure and consider heat storage flux when we investigate the energy balance of forest ecosystems.

Propionibacteria Fed to Dairy Cows: Effects on Energy Balance, Plasma Metabolites and Hormones, and Reproduction

To determine the effect of feeding Propionibacteria on energy balance, milk yield, and composition, metabolites and hormones of early-lactating dairy cows, multiparous Holstein cows were individually fed a total mixed ration from −2 to 12 wk postpartum with no addition (control, n = 10) or with an additional 17g of Propionibacteria culture daily (Treated, n = 9). Daily feed intake and milk production were recorded. Plasma cholesterol, nonesterified fatty acids (NEFA), leptin, insulin, glucose, insulin-like growth factor-I (IGF-I), IGF-binding proteins (IGFBP), and progesterone concentrations were measured up to twice weekly. Cows fed supplemental Propionibacteria had improved energy balance at wk 1 of lactation and had lower DMI per kg of body weight than control cows on wk 3 to 7, 10, and 12. Cows fed Propionibacteria had a greater percentage of milk protein and solids-not-fat and plasma NEFA concentrations than did control cows only at wk 1 of lactation. Treatment did not affect milk production or percentage of milk fat and lactose. Leptin levels were greater in treated than control cows throughout the study. Plasma glucose, insulin, cholesterol, IGFBP-3, and IGF-I concentrations were not affected by feeding Propionibacteria, but those variables increased with week postpartum. Plasma IGFBP-2 and IGFBP-5 levels decreased with week postpartum. Measures of reproductive and ovarian function did not differ between Propionibacteria-treated and control cows. Feeding Propionibacteria culture to transition and early lactating dairy cows may hold potential for improved milk protein production and metabolic efficiency during early lactation, without affecting reproductive function.

Dietary recommendations and athletic menstrual dysfunction.

Exercise-induced or athletic menstrual dysfunction (amenorrhoea, oligomenorrhoea, anovulation, luteal phase deficiency, delayed menarche) is more common in active women and can significantly affect health and sport performance. Although athletic amenorrhoea represents the most extreme form of menstrual dysfunction, other forms can also result in suppressed estrogen levels and affect bone health and fertility. A number of factors, such as energy balance, exercise intensity and training practices, bodyweight and composition, disordered eating behaviours, and physical and emotional stress levels, may contribute to the development of athletic menstrual dysfunction. There also appears to be a high degree of individual variation with respect to the susceptibility of the reproductive axis to exercise and diet-related stresses. The dietary issues of the female athlete with athletic menstrual dysfunction are similar to those of her eumenorrhoeic counterpart. The most common nutrition issues in active women are poor energy intake and/or poor food selection, which can lead to poor intakes of protein, carbohydrate and essential fatty acids. The most common micronutrients to be low are the bone-building nutrients, especially calcium, the B vitamins, iron and zinc. If energy drain is the primary contributing factor to athletic menstrual dysfunction, improved energy balance will improve overall nutritional status and may reverse the menstrual dysfunction, thus returning the athlete to normal reproductive function. Because bone health can be compromised in female athletes with menstrual dysfunction, intakes of bone-building nutrients are especially important. Iron and zinc are typically low in the diets of female athletes if meat products are avoided. Adequate intake of the B vitamins is also important to ensure adequate energy production and the building and repair of muscle tissue. This review briefly discusses the various factors that may affect athletic menstrual dysfunction and two of the proposed mechanisms: the energy-drain and exercise-intensity hypotheses. Because energy drain can be a primary contributor to athletic menstrual dysfunction, recommendations for energy and the macro- and micronutrients are reviewed. Methods for helping the female athlete to reverse athletic menstrual dysfunction are discussed. The health consequences of trying to restrict energy intake too dramatically while training are also reviewed, as is the importance of screening athletes for disordered eating. Vitamins and minerals of greatest concern for the female athlete are addressed and recommendations for intake are given.

Polyunsaturated fatty acid regulation of gene transcription: a mechanism to improve energy balance and insulin resistance.

This review addresses the hypothesis that polyunsaturated fatty acids (PUFA), particularly those of the n-3 family, play essential roles in the maintenance of energy balance and glucose metabolism. The data discussed indicate that dietary PUFA function as fuel partitioners in that they direct glucose toward glycogen storage, and direct fatty acids away from triglyceride synthesis and assimilation and toward fatty acid oxidation. In addition, the n-3 family of PUFA appear to have the unique ability to enhance thermogenesis and thereby reduce the efficiency of body fat deposition. PUFA exert their effects on lipid metabolism and thermogenesis by upregulating the transcription of the mitochondrial uncoupling protein-3, and inducing genes encoding proteins involved in fatty acid oxidation (e.g. carnitine palmitoyltransferase and acyl-CoA oxidase) while simultaneously down-regulating the transcription of genes encoding proteins involved in lipid synthesis (e.g. fatty acid synthase). The potential transcriptional mechanism and the transcription factors affected by PUFA are discussed. Moreover, the data are interpreted in the context of the role that PUFA may play as dietary factors in the development of obesity and insulin resistance. Collectively the results of these studies suggest that the metabolic functions governed by PUFA should be considered as part of the criteria utilized in defining the dietary needs for n-6 and n-3 PUFA, and in establishing the optimum dietary ratio for n-6:n-3 fatty acids.

Energy and nutrient status of amenorrheic athletes participating in a diet and exercise training intervention program.

Chronic energy deficit is one of the strongest factors contributors to exercise-induced menstrual dysfunction. In such cases, macro- and micronutrient intakes may also be low. This study presents the results of a diet and exercise training intervention program. designed to reverse athletic amenorrhea, on improving energy balance and nutritional status in 4 amenorrheic athletes. The 20-week program provided a daily sport nutrition supplement and 1 day of rest/week. The program increased protein intakes for the 3 athletes with a protein deficit to within the recommended levels for active individuals. Micronutrient intakes increased, as did serum concentrations of vitamin B12, folate, zinc, iron, and ferritin. These results indicate that some amenorrheic athletes have poor nutritional status due to restricted EIs and poor food selections. A sport nutrition supplement may improve energy balance and nutritional status in active amenorrheic women.

Maximal parenteral glucose oxidation in hypermetabolic young children: a stable isotope study.

During periods in which nutrition support of critically ill young children must be parenteral, glucose infusions are administered at up to 10 or more mg.kg-1.min-1 to meet predicted energy needs. However, data in adults suggest that such high glucose loads exceed the ability to oxidize glucose in the hormonal milieu that characterizes critical illness. The purpose of this study was to determine if these high glucose loads are oxidized by critically ill young children. Ten young children with serious burns were enrolled in a stable isotope study of glucose metabolism. These five boys and five girls were an average age of 5.2 years (range, 1 to 11 years), weight of 18.4 kg (range, 10 to 31 kg) and burn size of 51.6% of the body surface (range, 35% to 86%). During clinically required episodes of parenteral nutrition support, we used the [13C6]glucose tracer to assess the efficacy of glucose oxidation at both 5 and 8 mg.kg-1.min-1. Serum glucose was recorded and indirect calorimetry was performed. The fraction of exogenous glucose oxidation fell from 59% +/- 5% to 47% +/- 5% (p < .05). Although there was a significantly increased level of total glucose oxidation (3.2 to 3.8 mg.kg-1.min-1), this increment (29% +/- 9%) was accompanied by a significant decrease in the efficiency of energy production, because the bulk of the additional glucose above 5 mg.kg-1.min-1 was not being oxidized. Plasma glucose concentration did not change (145 +/- 4 vs 137 +/- 4 mg/dL, p < .01) and whole-body expired gas respiratory quotients remained consistent with a mixed fuel oxidation, implying that there exists an increased rate of exogenous glucose uptake by tissues in nonoxidative pathways. Maximum glucose oxidation in severely burned children occurs at intakes approximating 5 mg.kg-1.min-1. Exogenous glucose in excess of this amount enters nonoxidative pathways and is unlikely to improve energy balance. Clinical markers such as serum glucose levels or expired respiratory quotient may not detect inefficient glucose utilization.

PHYSICAL ACTIVITY AND THE PRIMARY PREVENTION OF CANCER

Evidence has been accumulating that suggests that physical activity may help reduce the risk of cancer. Physically active people have been shown to have a decreased rate of all-cancer mortality. The incidence of colon, breast, and perhaps prostate cancer are decreased in more active people when compared with their sedentary peers. Chronic physical activity may decrease tumor risk by its effect on natural immunity, antioxidant defenses, improved energy balance, hormonal changes, or by other unknown mechanisms.

Energy metabolism after ischemic preconditioning in streptozotocin-induced diabetic rat hearts.

The aim of this study was to compare the cardioprotective effects of preconditioning in hearts from streptozotocin-induced diabetic rats with its effects in normal rat hearts. The protective effect of ischemic preconditioning against myocardial ischemia may come from improved energy balance. However, it is not known whether preconditioning can also afford protection to diabetic hearts. Isolated perfused rat hearts were either subjected (preconditioned group) or not subjected (control group) to preconditioning before 30 min of sustained ischemia and 30 min of reperfusion. Preconditioning was achieved with two cycles of 5 min of ischemia followed by 5 min of reperfusion. In the preconditioned groups of both normal and diabetic rats, left ventricular developed pressure, high energy phosphates, mitochondrial adenosine triphosphatase and adenine nucleotide translocase activities were significantly preserved after ischemia-reperfusion; cumulative creatine kinase release was smaller during reperfusion; and myocardial lactate content was significantly lower after sustained ischemia. However, cumulative creatine kinase release was less in the preconditioned group of diabetic rats than in the preconditioned group of normal rats. Under ischemic conditions, more glycolytic metabolites were produced in the diabetic rats (control group) than in the normal rats, and preconditioning inhibited these metabolic changes to a similar extent in both groups. The present study demonstrates that in both normal and diabetic rats, preservation of mitochondrial oxidative phosphorylation and inhibition of glycolysis during ischemia can contribute to preconditioning-induced cardioprotection. Furthermore, our data suggest that diabetic myocardium may benefit more from preconditioning than normal myocardium, possibly as a result of the reduced production of glycolytic metabolites during sustained ischemia and the concomitant attenuation of intracellular acidosis.

Experiences of wastewater treatment in Chilean forest industry

The present situation of water treatment facilities in the forest industry of Chile is briefly described. Some data of the Chilean pulp mill production and the present level of water pollution are shown. This paper is the result of five years of applied research conducted to study and evaluate liquid effluent treatment from pulp, paper and board mills. We describe laboratory results corresponding to three industrial mills that we have studied. The first case presented in this paper corresponds to a bleached Kraft pulp mill with a fiber line consisting in a MCC digester, a delignification unit and four steps in bleaching. In this mill the effluents are treated in an extended lagoon and the suspended solids are settled in a primary treatment. Lab scale lagoons were installed to developed start up strategies and to determine optimal operational efficiencies. The second case that we present is a paper mill, with primary treatment in an air flotation unit used for separating suspended solids. A technical economical analysis was necessary to burn solid sludge in order to improve energy balance. Finally, the third case we have studied corresponds to a hardboard mill effluent. In this case, high COD, mainly as colloidal solids, characterize this effluent. Laboratory experiences were made using a system of two sequential aerated lagoons.

Experiences of wastewater treatment in chilean forest industry

The present situation of water treatment facilities in the forest industry of Chile is briefly described. Some data of the Chilean pulp mill production and the present level of water pollution are shown. This paper is the result of five years of applied research conducted to study and evaluate liquid effluent treatment from pulp, paper and board mills. We describe laboratory results corresponding to three industrial mills that we have studied. The first case presented in this paper corresponds to a bleached Kraft pulp mill with a fiber line consisting in a MCC digester, a delignification- unit and four steps in bleaching. In this mill the effluents are treated in an extended lagoon and the suspended solids are settled in a primary treatment. Lab scale lagoons were installed to developed start up strategies and to determine optimal operational efficiencies. The second case that we present is a paper mill, with primary treatment in an air flotation unit used for separating suspended solids. A technical economical analysis was necessary to bum solid sludge in order to improve energy balance. Finally, the third case we have studied corresponds to a hardboard mill effluent. In this case, high COD, mainly as colloidal solids, characterize this effluent. Laboratory experiences were made using a system of two sequential aerated lagoons.

Relationships between energy balance and post-partum ovarian activity and fertility in first lactation dairy cows

AbstractForty primiparous Holstein dairy cows were monitored from calving through 100 days in milk to evaluate the effect of energy balance in the early post-partum period on subsequent fertility. The post-partum interval to first ovulation (R2 = 0·41; P &lt; 0·005) was lengthened by greater negative energy balance, and reduced by greater body weight at parturition or decreased body-weight loss during the experimental period. Luteal activity (R2 = 0·58; P &lt; 0·0001), measured by plasma progesterone area under curve, was increased in the first cycle post partum by a shorter interval to first ovulation, improved energy balance during the 1st week of lactation and by decreased body-weight loss. Pregnancy status following first artificial insemination was related positively to the number of ovulations before insemination, improved energy balance during the 1st month post partum, fewer days to first ovulation and greater body weight at calving. These data suggest that energy balance and body weight are important in determining the post-partum interval to first ovulation and the subsequent fertility of first lactation dairy cotes.