Feed restriction of lactating cows triggers acute downregulation of mammary mTOR signaling and chronic reduction of mammary epithelial mass.

While there is generally no consensus about how nutrients determine milk synthesis in the mammary gland, it is likely that the mechanistic target of rapamycin complex 1 (mTORC1) plays a role as a key integrator of nutritional and mitogenic signals that can influence a multitude of catabolic and anabolic pathways. The objectives of this study were to evaluate acute changes (<24 h) in translational signaling, in addition to chronic changes (14 d) in mammary gland structure and composition, in response to a severe feed restriction. Fourteen lactating Holstein dairy cows were assigned to either ad libitum feeding (n = 7), or a restricted feeding program (n = 7). Feed-restricted cows had feed removed after the evening milking on d 0. Mammary biopsies and blood samples were collected 16 h after feed removal, after which cows in the restricted group were fed 60% of their previously observed ad lib intake for the remainder of the study. On d 14, animals were sacrificed and mammary glands dissected. In response to feed removal, an acute increase in plasma nonesterified fatty acid concentration was observed, concurrent to a decrease in milk yield. In mammary tissue, we observed downregulation of the mTORC1-S6K1 signaling cascade, in addition to reductions in mRNA expression of markers of protein synthesis, endoplasmic reticulum biogenesis, and cell turnover (i.e., transcripts associated with apoptosis or cell proliferation). During the 14 d of restricted feeding, animals underwent homeorhetic adaptation to 40% lower nutrient intake, achieving a new setpoint of 14% reduced milk yield with 18% and 29% smaller mammary secretory tissue dry matter and crude protein masses, respectively. On d 14, no treatment differences were observed in markers of protein synthesis or mammary cell turnover evaluated using gene transcripts and immunohistochemical staining. These findings implicate mTORC1-S6K1 in the early phase of the adaptation of the mammary gland's capacity for milk synthesis in response to changes in nutrient supply. Additionally, changes in rates of mammary cell turnover may be transient in nature, returning to basal levels following brief alterations that have sustained effects.

A Randomised Controlled Trial of Postoperative Sensitivity after Class II Restoration with Bulk-Fill vs Conventional Composites.

INTRODUCTION: Bulk-fill composites may simplify posterior restorations, saving time and reducing technical complexity. Post-operative sensitivity is a risk of posterior composites; bulk-fill composites could mitigate this. This single centre, double-blinded, parallel groups randomised controlled trial compared postoperative sensitivity following restoration of class II carious lesions with bulk-fill or conventional, layered composite. NULL HYPOTHESIS: there will be no difference in post-operative sensitivity between the two materials. METHODS: Participants requiring class II restoration of posterior teeth were randomised to bulk-fill (FU) (Coltene Fill-UpTM) or conventional, layered (BE) (Coltene Brilliant Everglow) composite. Allocation was concealed during cavity preparation. Only the operating dentist knew allocation. The outcome was 24 h post-operative sensitivity. RESULTS: 41 patients were randomised (20/group). Two patients from FU group were excluded from analysis (factors unrelated to intervention). There was no difference in postoperative sensitivity at 24 h nor any time point. Only participant age and baseline sensitivity scores significantly impacted post-operative sensitivity. One restoration debonded in FU group at 10 days, with no other adverse effects. No difference in time taken to place restorations was seen. CONCLUSIONS: Within the study's limitations, post-operative sensitivity after class II posterior restorations was no different in bulk-fill restorations compared with conventional, incrementally cured composite.

Evaluating lactation performance of multiparous dairy cattle to prepartum and/or postpartum supplementation of fat-embedded calcium gluconate.

Prebiotic compounds may be supplemented in the diet to improve animal health and performance in a variety of ways. In dairy cattle, the transition from pregnancy through parturition and lactation represents a critical life stage with many concurrent stressors. The objectives of this study were to evaluate responses to the provision of a hindgut-targeted prebiotic compound (calcium gluconate; HFCG) when supplemented prepartum and/or postpartum in a 2 × 2 factorial design. One hundred and sixty-four multiparous Holstein cattle were enrolled and followed from approximately 21 d prior to calving until 100 d of lactation. Treatments were administered as a pelleted compound feed offered in the rotary milking parlor once daily prepartum and thrice daily postpartum. Information pertaining to milk production and body weight were automatically recorded by the milking equipment, and information pertaining to reproductive and health performance was recorded by farm staff. Cattle that received HFCG prepartum were confirmed pregnant approximately 21 d earlier (P = 0.024). Cattle that received HFCG both pre- and postpartum had 9% to 10% higher yields of milk protein, fat, and energy-corrected milk (P ≤ 0.037) from weeks 4 to 9 of lactation relative to those that received HFCG exclusively prepartum. Conversely, cattle that received HFCG exclusively postpartum had 9% to 10% higher yields of milk protein, fat, and energy-corrected milk (P ≤ 0.037) from weeks 9 to 14 of lactation relative to those that received exclusively the negative control in both periods. The mechanism underlying these responses remains unclear, however, we hypothesize that these responses are due to localized reductions in inflammation in the gut and/or signaling to extragastrointestinal tissues altering energy partitioning and balance.

Dose response to postruminal urea in lactating dairy cattle.

Inclusion of urea in dairy cattle diets is often limited by negative effects of high levels of feed urea on dry matter intake (DMI) and efficiency of rumen N utilization. We hypothesized that supplying urea postruminally would mitigate these limitations and allow greater inclusion of urea in dairy cattle diets. Four rumen-fistulated Holstein-Friesian dairy cows (7 ± 2.1 lactations, 110 ± 30.8 d in milk; mean ± standard deviation) were randomly assigned to a 4 × 4 Latin square design to examine DMI, milk production and composition, digestibility, rumen fermentation, N balance, and plasma constituents in response to 4 levels of urea continuously infused into the abomasum (0, 163, 325, and 488 g/d). Urea doses were targeted to linearly increase the crude protein (CP) content of total DMI (diet plus infusion) by 0%, 2%, 4%, and 6% and equated to 0%, 0.7%, 1.4%, and 2.1% of expected DMI, respectively. Each 28-d infusion period consisted of a 7-d dose step-up period, 14 d of adaptation, and a 7-d measurement period. The diet was fed ad libitum as a total mixed ration [10.9% CP, 42.5% corn silage, 3.5% grass hay, 3.5% wheat straw, and 50.5% concentrate (dry matter basis)] and was formulated to meet 100%, 82%, and 53% of net energy, metabolizable protein, and rumen-degradable protein requirements, respectively. Linear, quadratic, and cubic effects of urea dose were assessed using polynomial regression assuming the fixed effect of treatment and random effects of period and cow. Dry matter intake and energy-corrected milk yield responded quadratically to urea dose, and milk urea content increased linearly with increasing urea dose. Apparent total-tract digestibility of CP increased linearly with increasing urea dose and ruminal NH3-N concentration responded quadratically to urea dose. Mean total VFA concentration was not affected by urea dose. The proportion of N intake excreted in feces decreased linearly and that excreted in urine increased linearly in response to increasing urea dose. The proportion of N intake excreted in milk increased linearly with increasing urea dose. Urinary urea excretion increased linearly with increasing urea dose. Microbial N flow responded cubically to urea dose, but the efficiency of microbial protein synthesis was not affected. Plasma urea concentration increased linearly with increasing urea dose. Regression analysis estimated that when supplemented on top of a low-CP diet, 179 g/d of postruminal urea would maximize DMI at 23.4 kg/d, corresponding to a dietary urea inclusion level of 0.8% of DMI, which is in line with the current recommendations for urea inclusion in dairy cattle diets. Overall, these results indicate that postruminal delivery of urea does not mitigate DMI depression as urea dose increases.

Review: Influence of postabsorptive metabolism on essential amino acid partitioning in lactating dairy cows.

In the lactating cow, essential amino acids (EAAs) absorbed from the gut are partitioned to mammary and extra-mammary tissues via blood plasma circulation. There is also entry of EAA into plasma from the breakdown of proteins in the cow's body. A balance model across plasma was solved to integrate entry rates of branched-chain (BCAA) and non-branched-chain EAA (NBAA) with their corresponding rate constants for clearance by mammary glands and the remainder of the body, for selected glucose and fat infusion experiments. Endogenous EAA entry from whole-body proteolysis was reduced by glucose and unchanged or increased by fat, the efficiency of net plasma BCAA clearance by mammary and extra-mammary tissues was elevated by glucose but slightly reduced by fat, and the efficiency of extra-mammary NBAA clearance may have decreased during glucose infusion but it was not affected or slightly increased by fat. These differences between glucose and fat responses can be accounted for by insulin and glucagon. Insulin suppresses endogenous EAA entry through mechanistic target of rapamycin complex 1, integrated stress response, and glycogen synthase kinase 3 signaling networks in skeletal muscle. While these networks can also regulate protein synthesis rates in muscle and the extra-mammary body, they exhibit low sensitivities to insulin in lactating ruminants. However, in the mammary glands, via these same networks, insulin stimulates clearance of EAA from plasma, although the drive to maintain a set point for milk protein yield takes precedence over nutritional signals. The glucose-induced increase in mammary BCAA clearance without an effect on NBAA clearance is due to a pronounced decrease in plasma BCAA concentrations. Because NBAAs do not experience a similar decline in concentration, the BCAA effect must be due to their metabolic transformation as opposed to sequestration in proteins. In adipose, the products of BCAA catabolism are lipogenic precursors. We propose that faster lipogenesis in adipose tissue, stimulated by glucose infusion, also promotes the uptake of precursor BCAA from plasma, causing a drop in their circulating concentrations. In addition, insulin stimulates BCAA oxidation in muscle as an alternative fuel to fatty acids. A lower efficiency of extra-mammary NBAA clearance during glucose infusion may be the consequence of decreased hepatic expression of AA-catabolizing enzymes in response to low glucagon concentration. The proportion of EAA entry partitioned to the mammary glands is a culmination of regulatory shifts at all of the points discussed above according to a regulated or unfair competition between mammary and extra-mammary processes.

Associations between feed efficiency and aspects of lactation curves in primiparous Holstein dairy cattle.

Genetic selection for improved feed efficiency in dairy cattle has received renewed attention over the last decade to address the needs of a growing global population. As milk yield is a critical component of feed efficiency metrics in dairy animals, our objective was to evaluate the associations between feed efficiency in primiparous Holstein cattle and parameters of a mathematical model describing individual lactation curves. The Dijkstra lactation curve model was fit to individual lactation records from 34 Holstein heifers with previously estimated measures of feed efficiency. We found that the optimal fit of the Dijkstra model was achieved using daily milk yield records up to 21 d in milk to capture the rise to peak milk yield and using monthly dairy herd improvement records for the remainder of lactation to accurately characterize lactation persistency. In the period of lactation before peak milk yield, improved feed efficiency was associated with a faster increase in daily milk yield over a shorter period of time at the expense of increased mobilization of body reserves; this serves to reinforce the concept that dairy cattle are primarily capital breeders versus income breeders. Feed efficiency in the period following peak lactation, as measured by gross feed efficiency, return over feed costs, and net energy efficiency of lactation, was positively associated with higher peak milk yield. The findings in early lactation suggest that estimates of feed efficiency could be improved by evaluating feed efficiency relative to conception, rather than parturition and lactation, to better account for the energy stored and released from body reserves in capital breeding.

Effects of supplemental calcium gluconate embedded in a hydrogenated fat matrix on lactation, digestive, and metabolic variables in dairy cattle.

There is growing evidence suggesting that by improving gut integrity and function, less energy is partitioned toward immune responses related to xenobiotic infiltration, sparing energy for productive purposes. Gluconic acid and its salts have previously shown prebiotic effects in the lower gut of nonruminant animals, where they serve as a precursor for butyrate, although evidence in ruminants is limited. Butyrate and its fermentative precursors have demonstrated multiple beneficial effects to gastrointestinal ecology, morphology, and function, such as the stimulation of epithelial cell proliferation and improvement of gut barrier function and ecology. The objective of this study was to evaluate changes in milk production, milk fatty acid composition, and fecal and blood parameters in lactating dairy cattle fed a hydrogenated fat-embedded calcium gluconate (HFCG) supplement designed to target the hindgut for calcium gluconate delivery. In addition, the effects of a compound feed processing method (i.e., incorporated into a mash or an extruded pellet) were tested to evaluate the effect of extrusion on product efficacy. Forty-five lactating Holstein cows at approximately 165 d in milk were used in a 3 × 3 Latin square consisting of three 28-d periods, during which animals were offered a basal ration mixed with 3 different compound feeds: a negative control in mash form containing no HFCG, or the HFCG supplement fed at a target rate of 16 g/d, delivered in either a mash or pelleted form. Supplementation of HFCG tended to increase yields of milk fat and fat- and energy-corrected milk. Total yields and concentrations of milk fatty acids ≥18 carbons in length tended to increase in response to HFCG. Plasma nonesterified fatty acids and milk urea increased in HFCG treatments. No differences were observed in fecal pH or fecal concentrations of volatile fatty acids, with the exception of isobutyrate, which decreased in HFCG-fed cows. Changes in milk fatty acid profile suggest that increased milk fat yield was driven by increased incorporation of preformed fatty acids, supported by increased circulating nonesterified fatty acid. Future research investigating the mode of action of HFCG at the level of the hindgut epithelium is warranted, as measured fecal parameters showed no response to treatment.

The dynamic behavior of feed efficiency in primiparous dairy cattle.

A variety of measures are currently used to evaluate feed efficiency in livestock, with some of the most popular being the linear regression of nutrient intake on the various energy sinks of the cohort being evaluated. The adoption of novel on-farm technologies has greatly increased the breadth and depth of data being collected on a daily basis, which creates the opportunity for the implementation of more advanced feed efficiency models. The objectives of the current study were to leverage data collected using high-throughput biometric technologies to evaluate changes of early-lactation feed efficiency on a daily basis and to develop a novel measure of feed efficiency based on the NRC net energy model. Daily records of nutrient intake, fat- and protein-corrected milk yield, body weight, and body condition score were used to model 7 different indices of feed efficiency (gross feed efficiency, return over feed costs, residual feed intake, residual net energy intake, and net energy efficiencies of lactation, maintenance, and body reserve flux) in primiparous Holstein heifers (n = 40) from 0 to 150 d in milk. We observed that feed efficiency was dynamic and fluctuated over the course of the experimental period regardless of the efficiency measure used, but most measures followed similar trends in changes of efficiency on a day-to-day basis. Of the measures evaluated, return over feed costs would be most suited for management purposes due to practicality and simplicity, whereas other measures, such as the efficiency of net energy flux to and from body reserves, present potential targets for inclusion in breeding goals. Net energy efficiency of lactation was estimated to have higher repeatability compared with residual feed or energy intake, which may reduce the time required to estimate whole-lactation efficiency. Because decreased net energy balance was strongly correlated with increased efficiency for all indices evaluated, future work investigating the associations of feed efficiency with the magnitude and duration of negative energy balance is warranted.

Invited review: Determination of large-scale individual dry matter intake phenotypes in dairy cattle.

Feed efficiency has been widely studied in many areas of dairy science and is currently seeing renewed interest in the field of breeding and genetics. A critical part of determining how efficiently an animal utilizes feed is accurately measuring individual dry matter (DM) intake. Currently, multiple methods are used to measure feed intake or determine the DM content of that feed, resulting in different levels of accuracy of measurement. Furthermore, the scale at which data need to be collected for use in genetic analyses makes some methodologies impractical. This systematic review aims to provide an overview of the current methodologies used to measure both feed intake in ruminants and DM content of feedstuffs, current methods to predict individual DM intake, and applications of large-scale intake measurements. Overall, advances in milk spectral data analysis present a promising method of estimating individual DM intake on a herd scale with further validation of prediction models. Although measurements of individual feed intake rely on the same underlying principle, the methods selected are largely dictated by the costs of capital, labor, and necessary analyses. Finally, DM methodologies were synthesized into a comprehensive protocol for use in a variety of feedstuffs.

Efficacy of irrigant activation techniques in removing intracanal smear layer and debris from mature permanent teeth: a systematic review and meta-analysis.

AIMS: To establish whether irrigant activation techniques (IATs) result in greater intracanal smear layer and debris removal than conventional needle irrigation (CNI). METHODOLOGY: Six electronic databases were searched to identify scanning electron microscopy studies evaluating smear layer and/or debris removal following the use of manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI) or apical negative pressure (ANP) IATs in mature permanent teeth. Meta-analyses were performed for each canal segment (coronal, middle, apical and apical 1 mm) in addition to subgroup analyses for individual IATs with respect to CNI. Outcomes were presented as standardized mean differences (SMD) alongside 95% confidence intervals (95% CI) and chi-squared analysis. RESULTS: From 252 citations, 16 studies were identified. The meta-analyses demonstrated significant improvements in coronal (SMD: 1.15, 95% CI: 0.72-1.57 / SMD: 0.54, 95% CI: 0.29-0.80), middle (SMD: 1.30, 95% CI: 0.59-2.53 / SMD: 0.8, 95% CI: 0.58-1.13) and apical thirds (SMD: 1.22, 95% CI: 0.83-1.62 / SMD: 1.86, 95% CI: 0.76-2.96) for smear layer and debris removal, respectively. In the apical 1 mm IATs improved cleanliness; however, differences were insignificant (SMD: 1.15, 95% CI: -0.47-2.77). Chi-squared analysis revealed heterogeneity scores of 79.3-92.8% and 0.0-93.5% for smear layer and debris removal, respectively. CONCLUSIONS: IATs improve intracanal cleanliness across a substantial portion of the canal, and therefore, their use is recommended throughout root canal preparation. However, current data is too heterogeneous to compare and identify superiority of an individual technique highlighting the need to standardize experimental protocols and develop a more representative research model to investigate the in vivo impact of IATs on clinical outcomes and periapical healing following root canal treatment.

Effective anaesthesia of the acutely inflamed pulp: part 2. Clinical strategies.

Achieving profound pulpal anaesthesia in a mandibular molar diagnosed with irreversible pulpitis can be argued to be the most testing of dental anaesthetic challenges. Following discussion on the possible reasons for this occurrence in part 1, part 2 outlines the various local anaesthetic techniques that practitioners can use to overcome the acutely inflamed mandibular molar. They should then be able to apply these same principles to help anaesthetise any other tooth presenting with an acutely inflamed pulp. Techniques are discussed in detail along with key variables that have been associated with having an impact on the anaesthetic efficacy. This is to bring to light factors that can aid anaesthetic success as well as dispel common misnomers.

Effective anaesthesia of the acutely inflamed pulp: part 1. The acutely inflamed pulp.

Achieving profound pulpal anaesthesia in a mandibular molar diagnosed with irreversible pulpitis can be argued to be the most testing of dental anaesthetic challenges. This can be attributed to the technical complexities of conventional techniques and the presence of pulp pathosis. Reasons for why the latter influences the ability to attain pulpal anaesthesia is not yet fully understood, but its frequent occurrence is well documented. In light of overcoming this it has become common practice to prescribe antibiotics, refer onto secondary care or to even commence treatment without appropriately anaesthetising the tooth. Therefore, this two part series aims to help practitioners attain clinically acceptable pulpal anaesthesia in the most testing of scenarios; the acutely inflamed mandibular molar. They should then be able to apply these same principles to other teeth presenting with similar symptoms. This section outlines the clinical presentation and pathophysiology associated with an acutely inflamed pulp, defines what it is to attain pulpal anaesthesia and critically analyses theories as to why these teeth are up to eight times more difficult to anaesthetise than their healthy counterparts.

The management of traumatic tooth loss with dental implants: part 2. Severe trauma.

In part 2 of this series, we look at the clinician's role in replacing multiple missing teeth and the associated soft tissues and bone, following severe forms of trauma. These patients usually wish to have fixed prostheses to help restore their appearance and function. In order to fulfil the patient's request, the multidisciplinary team can be faced with significant challenges, often requiring extensive reconstructive surgery and complex implant oral rehabilitation. The aim of this paper is to highlight to the general dental practitioner some of the challenges faced in rehabilitating severe trauma patients with implant retained prosthesis. By understanding the challenges it is hoped that the general dental practitioner will be able to make an assessment of the clinical situation and seek appropriate specialist advice to ensure optimal results for their patients. In the longer term, the management of these patients requires a shared care approach between the general dental practitioner and relevant specialists.

Clinical case reports using a novel calcium-based cement.

A novel calcium-based cement was launched in 2009 claiming to be a revolutionary material capable of offering a bioactive and biocompatible replacement for dentine. The calcium-based cement has been reported to encourage the repair and regeneration of lost dental tissue, preserve pulp vitality, promote pulp healing and provide a bioactive substitute for natural dentine. This article looks at two clinical cases using this new material for endodontic purposes.

A biocompatible and bioactive replacement for dentine: is this a reality? The properties and uses of a novel calcium-based cement.

As part of the continuing evolution towards conservative dentistry there has been a drive to push further and investigate the possibility of inducing the repair and regeneration of lost dental hard tissue. Until recently, the prospect of repair and regeneration had been confined to laboratory studies and hypothesised scientific models. In 2009, a new product was launched claiming to be a revolutionary material capable of offering a bioactive and biocompatible replacement for dentine. The calcium-based cement is reported to preserve pulp vitality, promote pulp healing and provide a natural substitute for dentine through bioactive stimulation of the dentino-pulpal complex. Its clinical indications are extensive, described as a restorative material suitable for use wherever dentine replacement is required. In this article the physical, mechanical, chemical and biological properties of this novel material are presented, together with the results of experimental laboratory-based investigations and on-going clinical in vivo investigations.

How should we investigate CUO (C-Reactive Protein elevation of unknown origin)? A case-based discussion of infective endocarditis in an octogenarian.

Infective endocarditis and other chronic infections may cause diagnostic difficulties, regardless of age. The likelihood of an atypical presentation of chronic infection probably increases with age. Serum CRP may be a useful guide to the presence of underlying infection and its resolution in older people. The term CUO (CRP elevation of unknown origin) may have a place in triggering further investigation for the presence of infection or other pathology.

Evaluation of the basic erosive wear examination (BEWE) for use in general dental practice.

OBJECTIVE: The basic erosive wear examination (BEWE) is a relatively new index proposed for the screening and recording of tooth wear in adults. The aim of this study was to test the validity and reliability of the BEWE. DESIGN: Cross sectional study of a sample of 164 adult patients. SETTING: General dental practice in East Lancashire, UK in 2010. SUBJECTS: Patients attending for routine examination or treatment. MAIN OUTCOME MEASURES: By screening patients with the BEWE and comparing the results to the established tooth wear index (TWI) the sensitivity and specificity of the BEWE was established.Results The BEWE predicted moderate to severe wear (BEWE grade 3) with a sensitivity of 48.6% and a specificity of 96.1%, and predicted severe wear with a sensitivity of 90.9% and a specificity of 91.5% (also BEWE score 3). Inter- and intra-examiner reliability for the BEWE were both moderate (κ(w) = 0.43 and 0.57 respectively). CONCLUSION(S): BEWE scores show a similar distribution to TWI scores and the examination is an effective screening test for severe tooth wear. The moderate levels of examiner reliability suggests the BEWE scores should be interpreted with some caution.