52 research outputs found
Effects of Microencapsulated Methionine on Milk Production and Manure Nitrogen Excretions of Lactating Dairy Cows
No full text: The study objective was to determine the effects of rumen-protected methionine (Met) by microencapsulation (RPM) on amino acid (AA) supply to the udder, milk production, and manure nitrogen (N) losses of dairy cows. A corn and soybean-based diet deficient in metabolizable Met (~10 g/d) was supplemented with RPM providing 0, 11.0, 19.3, and 27.5 g/d of Met. Dry matter intake (DMI), milk production, plasma essential AA (EAA), mammary plasma flow (MPF), and fecal (FN) and urinary N (UN) outputs (g/d) were determined. The RPM increased linearly milk yield, milk protein yield, and energy corrected milk yield (p < 0.040) without affecting DMI. Milk protein yield increased by 50 g/d for the 19.3 vs. 0 g/d dose (p = 0.006) but the rate of increment decreased for 27.5 g/d dose. Plasma Met, and MPF increased linearly with RPM dose (p < 0.050). Apparent total tract digestibility of crude protein (p = 0.020) and FN (p = 0.081) decreased linearly with RPM. The UN did not change but total manure N decreased linearly with RPM (p = 0.054). The RPM (19.3 g/d) seemed to help cows overcome the metabolizable Met deficiency while mitigating manure N excretions to the environment
Effects of drinking water on feed intake, growth performance, health status, nutrient digestibility and composition of gut microbiota in young dairy calves
No full textThere is a lack of data on water consumption and its role in dairy calves. The water requirements of dairy calves are negligibly defined. Producers pay little attention to whether calves consume enough drinking water (also called free water) as they consider water in milk or milk replacer would satisfy the total water requirement. A recent USDA survey revealed that dairy producers wait on average 17 d to first offer drinking water to newborn calves. Unlike milk or milk replacer directly shunted to the abomasum, drinking water first enters the rumen and then moves to the rest of the gastrointestinal tract. Therefore, drinking water presumably play a unique role in the development of gut and its microbiome in turn affecting nutrient intake, nutrient digestibility, and growth. The present study was conducted 1) to determine if newborn calves consume significant amount of free water separate from the water in milk, and 2) to examine the effects of offering drinking water since birth (W0) vs. 17 days later (W17) on starter intake, health status, growth, nutrient digestibility, and the composition of gut microbiota in young dairy calves. Thirty Holstein heifer calves were randomly assigned to W0 or W17 (n = 15). Calves had free access to drinking water and a starter ration, and bottle-fed with pasteurized waste milk until weaning at 49 d of age. Fresh fecal samples were collected directly from the rectum at 14, 42, and 70 d of age. The DNA were extracted from fecal samples and sequenced using 16S rRNA gene-amplicon sequencing on an Illumina MiSeq system. The sequences were clustered into operational taxonomic units with a 99% similarity threshold. Total fecal output of individual calves was measured over two consecutive days to determine apparent total-tract digestibility (ATTD) of nutrients three weeks post-weaning. Newborn calves consumed a significant amount (0.75±0.05 kg/d) water separate from the water in milk during the first 16 d. Once offered, W17 drank 59% more free water than W0 during the rest of the pre-weaning period. Starter intake of W0 and W17 was similar, but W0 consumed 0.285 kg/d more milk and tended to achieve greater BW and heart girth (HG) compared to W17 during the pre-weaning period. Offering water from birth versus offering it later did not affect the number of days with diarrhea, intensity of diarrhea, and blood hematocrit values. Despite a similar starter intake, W0 had greater hip height, body length, ATTD of ADF and NDF, and gain: feed ratio than W17 post-weaning. At 14 d of age, feces from W0 had a greater number of bacterial species (5908 vs. 4698, P = 0.033) and species richness (Chao1 index, P = 0.042) than feces from W17. The number of bacterial species, and Chao1 index increased with age (P < 0.001) and became similar between W0 and W17 at 42 d of age. At 42 d of age, the abundance of Faecalibacterium prausnitzii, and Bifidobacterium breve previously shown to improve gut health and growth were greater in W0 than W17 (P < 0.040). Overall, the present study highlighted that offering drinking water since birth has a potential to improve growth, nutrient digestibility, feed conversion efficiency, and the abundance of beneficial bacterial communities in the gut of young dairy heifer calves.</p
Regulatory Roles of Essential Amino Acids, Energy, and Insulin in Mammary Cell Protein Synthesis
No full textDairy cows inefficiently convert dietary protein to milk protein causing economic and environmental costs. Amino acids (AA), insulin, and glucose significantly enhance muscle protein synthesis efficiencies. The objectives of this research project were 1) to investigate the regulatory effects of essential AA (EAA) and their interactions with insulin, glucose and acetate on mammary protein synthesis rates, 2) to investigate whether branched chain amino acids (BCAA): leucine , isoleucine , and valine , become limiting for milk protein synthesis when Met and Lys supply were not limiting, and 3) to develop a mathematical representation for the EAA and insulin effects on cellular signals for protein synthesis. MAC-T cells were treated with EAA, insulin, glucose, and acetate to observe their individual and interactive effects on phosphorylation of mTOR, rpS6, S6K1, 4EBP1, eEF2, eIF2α, Akt, and AMPK. These signaling effects on protein synthesis rates were examined with mammary tissue slices. A mathematical representation of the insulin and EAA effects was developed. The effects of supplementing BCAA on milk protein synthesis were investigated using nine Holstein cows, assigned to 7 d continuous jugular infusions of saline, Met and Lys, and Met and Lys plus BCAA.
Multiple essential amino acids, Leu, Ile, Met, and Thr were able to substantially regulate protein synthesis rates in bovine mammary cells by increasing (P < 0.05) phosphorylation of mTOR, S6k1, 4EBP1, and decreasing (P < 0.10) eEF2 phosphorylation. Insulin considerably (P < 0.10) exerted similar signaling effects in MAC-T cells, independent of EAA. Supplementation of only acetate increased (P = 0.09) mammary cell energy status as indicated by reduced AMPK phosphorylation in MAC-T cells. Neither acetate nor glucose had substantial regulatory effects on mammary protein synthesis rates. Although Met and Lys supplementation increased (P < 0.01) milk protein yields and protein efficiencies, there were no apparent benefits of BCAA supplementation under the feeding circumstances of our study. The developed mathematical model adequately represented the regulatory effects of EAA and insulin. Such mathematical representations of regulatory effects of EAA and their interaction with other nutrients may improve our current AA requirement models to predict AA requirements of dairy cows with increased accuracy.Ph. D
Evaluating Performance of Metal-Organic Complexes as Electrodes in Hydrogen Peroxide Fuel Cells
No full textWith increasing energy demands, fuel cells are a popular avenue for portability and low waste emissions. Hydrogen fuel cells are popular due to their potential output power and clean waste. However, due to storage and transport concerns, hydrogen peroxide fuel cells are a promising alternative. Although they have a lower output potential compared to hydrogen fuel cells, peroxide can act as both the oxidizing and reducing agent, simplifying the structure of the cell. In addition to reducing the complexity, hydrogen peroxide is stable in liquid form and can be stored in less demanding methods. This paper investigates chelated metals as electrode material for hydrogen peroxide fuel cells. Chelated metal complexes are ring-like structures that form from binding organic or inorganic compounds with metal ions. They are used in medical imaging, water treatment, and as catalysts for reactions. Copper(II) phthalocyanine, phthalocyanine green, poly(copper phthalocyanine), bis(ethylenediamine)copper(II) hydroxide, iron(III) ferrocyanine, graphene oxide decorated with Fe3O4, zinc phthalocyanine, magnesium phthalocyanine, manganese(II) phthalocyanine, cobalt(II) phthalocyanine are investigated as electrode materials for peroxide fuel cells. In this study, the performance of these materials is evaluated using cyclic voltammetry. The voltammograms are compared, as well as observations are made during the materials’ use to measure their effectiveness as electrode material. There has been limited research comparing the use of these chelated metals in the context of hydrogen peroxide fuel cells. Through this research, the goal is to further the viability of hydrogen peroxide fuel cells. Poly(copper phthalocyanine) and graphene oxide doped with iron oxides had strong redox catalytic activity for use in acidic peroxide single-compartment fuel cells, where the poly(copper phthalocyanine) electrode compound generated the highest peak power density of 7.92 mW/cm2 and cell output potential of 0.634 V
Effects of Age of Dairy Calves First Offered Free Drinking Water on Feed Intake, Growth, and Health
No full textOffering adequate amount of clean drinking water to dairy calves has become recently a significant concern in the dairy industry. This also brought attention to the fact that many dairy farmers wait for a couple of weeks to offer drinking water to newly borne calves even though offering water from birth is the recommendation. Neonate calves could consume considerable amount of water via whole milk or milk replacer but it’s not clear that amount alone would fulfill the water requirements to support growth and development. The present study was conducted to examine the effects of receiving drinking water from birth or about two weeks (wk) later on water and grain intake, and growth and health performances of Holstein heifer calves receiving a large amount (6 to 9 kg/d) of whole milk. The results revealed that, when offered from birth, calves drank significant amount (0.70 kg) of water in addition to a large amount of water they received via whole milk (about 5.0 kg/d) during the first two weeks of their life. Calves not receiving drinking water from birth consumed more grain and drank more water, once offered. Nonetheless, both groups achieved similar drinking water and grain intakes by the time they were 5 wk old. Regardless of the water and grain intake differences during neonate life, calves receiving or not receiving drinking water from birth had similar growth rates and body weight from birth to 10 wk of age. Nonetheless, calves receiving water from birth tended to have lower scours scores, and greater body lengths and hip heights after weaning compared to the calves receiving drinking water later. Overall, offering drinking water to calves from birth itself appeared to offer positive benefits even in systems promoting a large amount of liquid feed (whole milk or milk replacer) intake.</p
Improving decision making, communication and documentation regarding advanced resuscitation decisions in a tertiary care hospital in Sri Lanka
No full textBackground: Resuscitation decisions made in advance are especially important to prevent negative patient outcomes at end-of-life. We conducted a clinical audit to assess the current practice of these decisions in Sri Lanka and then introduced interventions to improve the same.
Methods: An auditor-administered questionnaire developed through a focused group discussion among experts was used to analyse the medical records of deaths during a period of sixty days focusing on advanced resuscitation decisions and factors affecting them. The junior doctors directly involved in the care of each patient were interviewed regarding their retrospective judgement about the most appropriate resuscitation decision, which was later compared with the decision of an expert panel, who decided on the most appropriate resuscitation decision based on the medical records of the patient. An educational session for doctors was then conducted to improve their knowledge about advanced resuscitation decisions including the importance of meticulous documentation of such decisions. The outcome was assessed after sixty days following the introduction of the intervention using the same questionnaire.
Results: There was a significant improvement in the number of documented advanced resuscitation decisions from 4/40 (10%) to 17/38 (44.73%) (Z=3.5, P=0.0006), with a significant increase in DNACPR decisions from 4/40 (10%) to 14/38 (36.8%) (Z= 2.8, P=0.005) following the intervention. Unsuccessful CPR attempts decreased significantly from 31/40 (77.5%) to 14/38 (36.8%) (Z=3.6, P=0.0003) in the post-intervention period. The resuscitation decisions suggested by junior doctors that matched with expert decisions increased significantly for both interns ((from 11/40 (27.5%) to 22/38 (57.9%) (Z=2.7, P=0.0066)) and registrars ((18/40 (45%) to 27/38 (71.05%) (Z=2.3, P=0.0202)) in the post-intervention period.
Conclusion: Documentation and practice regarding advanced resuscitation decisions are suboptimal in Sri Lanka. This can be improved by interventions targeting improving the knowledge about the concept and its proper documentation among health care professionals
Nutritional interventions for dairy calves undergoing weaning and heat stresses
No full textDairy calves experience marked growth depressions during weaning and heat stress. Inflammation and oxidative stress are responsible for a considerable portion of that growth depression, and represent serious animal welfare concerns. The intestinal barrier function impairment is a leading cause of inflammation in young animals undergoing weaning or exposed to heat stress. As far as weaning is concerned, step-down weaning schemes are proposed to mitigate the growth slumps and associated stresses. However, the literature suggests the need to optimize those schemes to achieve expected outcomes. Despite the environmental management tools such as fans and misters to mitigate heat stress, the subpar performance of heat-stressed cattle demands nutritional interventions to mitigate the intestinal barrier function damage, inflammation, and oxidative stress. Data on pigs and poultry show that functional amino acids such as glutamine (Gln) and branched-chain amino acids (BCAA), and phytogenic feed additives (PFA) are promising strategies to alleviate the negative consequences of weaning and heat stress. This dissertation focused on evaluating those nutritional interventions in weaning and heat-stressed calves under the hypothesis that the effects seen in monogastric species would be true for dairy calves.
Chapter 2 describes a study to examine the effects of a Gln supplementation (2.0% of DMI) in a step-down weaning scheme on starter feed intake (SFI), average daily gain (ADG), paracellular permeability of intestinal epithelium (PPIE), and inflammation markers of dairy heifer calves weaned from a high milk volume (9.0 L/d). The step-down weaning was initiated by decreasing the milk volume to 3.0 L/d, and calves continued to receive the 3.0 L/d milk until they were weaned completely with a 1.0 kg/d SFI. Glutamine was fed dissolved in the 3.0 L/d milk, and PPIE was determined with lactulose: D-mannitol (LMR) in blood serum 1.0 h after feeding those sugars in milk using gas chromatography-mass spectrometry (GC-MS). The responses of calves beginning the scheme at 35 d of age with, or without Gln were compared with that of calves beginning the scheme without Gln at 49 d of age (n = 12). Additionally, an in vitro experiment with calf intestinal epithelial cells (CIEC) was conducted to elucidate the impact of Gln on the tight junction protein abundance and the localization to the cell membrane. The in vivo study results revealed that the milk volume restriction at 35 d negated ADG during weaning. The supplementation of Gln tended to increase the ADG to a level similar to that of calves beginning weaning without Gln at 49 d. Calves with Gln increased the SFI faster and completed weaning 3 d earlier than calves without Gln (51 vs. 54 d of age). Despite the SFI increase, serum BCAA concentrations decreased more rapidly in calves with vs. without Gln. Regardless of the age, weaning without Gln increased LMR 7 d after the milk restriction, whereas calves with Gln did not experience such an LMR increase. Blood haptoglobin, and LPS-binding protein concentrations, however, increased earlier than the LMR increase suggesting that inflammation might have preceded the PPIE increase in response to the milk volume restriction. The in vitro experiment results revealed a 2 to 3-fold increase in tight junction protein expression in CIEC when media Gln concentration increased from 0.0 to ≥5.0 mM. The extracellular Gln supplementation improved energy status but did not affect the localization of tight junction proteins to the cell membrane of CIEC. Overall, the supplementation of Gln at 2.0% of DMI could improve ADG and preserve intestinal barrier function of dairy calves weaned from a high milk volume without affecting post-weaning growth or SFI.
In the following study (Chapter 3), the Gln supplementation was decreased from 2.0 to 1.0% of DMI as the literature showed that the 1.0% supplementation was related to >5.0 mM Gln in the intestinal lumen of weaning piglets. Moreover, the 1.0% supplementation of Gln improved feed intake, ADG, and immune responses of piglets undergoing weaning and transportation stresses. Given the critical roles of BCAA as precursors and stimulatory signals in muscle growth, BCAA at the ratio of milk protein (17, 10, and 11 g/d Leu, Ile, and Val, respectively) were supplemented with the 1.0% Gln dose (~8.0 g/d). The Gln and BCAA supplementations were hypothesized to mitigate additively the growth slump of dairy calves undergoing the step-down weaning from a high milk volume at an early age of 35 d (n = 11). As observed in the previous experiment, the milk volume restriction (9.0 to 3.0 L/d) negated the ADG, but the 1.0% Gln supplementation did not affect ADG, SFI, or the efficiency (ADG: SFI) during weaning (35 to ~50 d of age). The supplementation of Gln and BCAA tended to increase ADG without affecting SFI and ADG: SFI during weaning. Neither Gln nor Gln+BCAA supplementations affected blood haptoglobin concentrations during weaning. Paradoxically, Gln and Gln+BCAA supplementations during weaning were associated with 9 and 18% decreases in SFI post-weaning (~50 to 70 d of age). Those SFI decreases were positively and negatively associated with plasma serotonin and leptin concentrations determined on the last day of the amino acid supplementations, respectively. Glutamine and BCAA fed in milk during weaning seemed to exert sustained and negative effects on the feed intake of dairy calves by modulating hormones secreted by the gastrointestinal tract.
Chapter 4 covers a study, which was aimed to evaluate a PFA added to a total mixed ration on DMI, ADG, indices of hyperthermia, and antioxidant and anti-inflammatory markers of weaned heifer calves (5-6 months old) subjected to a cyclic heat stress bout (HS) in the summer. Calves were fed total mixed ration with or without PFA (n = 11) for 7 d under usual summer conditions (the baseline), and then subjected to HS employed by setting the barn temperature at 33 °C during the daytime (0900 to 2000 h) for 7 d. Similar to what was observed with weaning, HS negated ADG relative to the baseline. However, the growth slump was not related to a DMI decrease indicating a substantial diversion of nutrients from growth, a significant energy efficiency decreases of growth, or both in response to HS. Calves decrease DMI during the day but ate more during the night making DMI similar between HS and the baseline. The PFA increased DMI during the day but did not affect the total daily DMI. Rectal temperature (>40 °C) and respiration rate (>120 breaths/min) indicated similar degrees of hyperthermia in calves with and without PFA. The blood carbon dioxide decreased, but oxygen increased in response to PFA postulating increased blood flow to the lungs, and perhaps to the periphery during HS. The blood inflammation markers, serum haptoglobin and plasma LPS-binding protein increased in calves without PFA while calves with PFA did not experience such a change in response to HS. Moreover, blood oxidative stress markers, plasma L-lactate, thiobarbituric acid reactive substances, protein carbonyl, and cortisol concentrations were lower in calves with PFA than calves without PFA during HS.
In summary, weaning from a high milk volume and summer heat stress bouts can result in substantial growth depression in dairy calves. The weaning-associated growth slumps were primarily a result of slow SFI increase and thus prolonged nutrient deficiencies. Nevertheless, the elevated blood markers of intestinal barrier function damage and inflammation of weaning calves indicate that energy diverted to other functions such as immune system activation could contribute to some part of the weight gain decline. The improved intestinal barrier function and weight gain improvement for Gln supplementation during weaning attest to such contribution. Nevertheless, supplementation of functional amino acids such as Gln and BCAA during weaning could negatively affect post-weaning SFI. Further investigation into the mechanisms involving those effects would explain the negative link between high milk volumes and SFI as Gln and BCAA represent a major part of free and protein-bound amino acid pools in milk. The diurnal heatwaves in the summer would not change daily DMI, as calves seem to consume more during the night to compensate for the DMI losses during extremely hot daytime. Despite the unchanged DMI, summer heat waves can result in zero weight gain in calves possibly due to the diversion of energy from growth to functions involved in thermoregulation and immune system activation. Feeding PFA often known to possess anti-inflammatory and antioxidant properties could improve health and wellbeing, but may not be potent enough to improve the weight gain of calves exposed to intense heat stress episodes. Nevertheless, further investigations into PFA addressing the variability in inclusion rates, diet composition, feeding duration, and interaction with other heat abatement practices would yield a better understanding of their potential to improve the growth of heat-stressed calves
Algebraic properties of Toeplitz operators on weighted Bergman spaces
No full textsummary:We study algebraic properties of two Toeplitz operators on the weighted Bergman space on the unit disk with harmonic symbols. In particular the product property and commutative property are discussed. Further we apply our results to solve a compactness problem of the product of two Hankel operators on the weighted Bergman space on the unit bidisk
- …
