SARS-CoV-2 incidence in secondary schools; the role of national and school-initiated COVID-19 measures.

INTRODUCTION: Our aim was to gain insight into the effect of COVID-19 measures on SARS-CoV-2 incidence in secondary schools and the association with classroom CO2 concentration and airborne contamination. METHODS: Between October 2020-June 2021, 18 schools weekly reported SARS-CoV-2 incidence and completed surveys on school-initiated COVID-19 measures (e.g. improving hygiene or minimizing contacts). CO2 was measured in occupied classrooms twice, and SARS-CoV-2 air contamination longitudinally using electrostatic dust collectors (EDC) and analyzed using RT-qPCR. National COVID-19 policy measures varied during pre-lockdown, lockdown and post-lockdown periods. During the entire study, schools were recommended to improve ventilation. SARS-CoV-2 incidence rate ratios (IRR) were estimated by Generalized Estimating Equation (GEE) models. RESULTS: During 18 weeks follow-up (range: 10-22) SARS-CoV-2 school-incidence decreased during national lockdown (adjusted IRR: 0.41, 95%CI: 0.21-0.80) and post-lockdown (IRR: 0.60, 0.39-0.93) compared to pre-lockdown. School-initiated COVID-19 measures had no additional effect. Pre-lockdown, IRRs per 10% increase in time CO2 exceeded 400, 550 and 800 ppm above outdoor level respectively, were 1.08 (1.00-1.16), 1.10 (1.02-1.19), and 1.08 (0.95-1.22). Post-lockdown, CO2-concentrations were considerably lower and not associated with SARS-CoV-2 incidence. No SARS-CoV-2 RNA was detected in any of the EDC samples. CONCLUSION: During a period with low SARS-CoV-2 population immunity and increased attention to ventilation, with CO2 levels most of the time below acceptable thresholds, only the national policy during and post-lockdown of reduced class-occupancy, stringent quarantine, and contact testing reduced SARS-CoV-2 incidence in Dutch secondary schools. Widespread SARS-CoV-2 air contamination could not be demonstrated in schools under the prevailing conditions during the study.

Hospital clinical research activity, rather than staff motivational engagement, significantly links effective staff communication and favourable patient feedback; a cross-sectional study.

OBJECTIVES: Healthcare staff behaviour can impact on the performance of hospitals. Staff involvement in clinical research can have a wider positive effect on patients and hospital performance. The aim of this study was to further assess the putative positive effect of clinical research activity on patient feedback with a more recent dataset, and if staff's motivational engagement levels may impact on aspects of in-patient feedback. METHODS: A retrospective cross-sectional study was conducted with (survey) data from 2019; the sample was 129 English National Health Service hospital Trusts. Sources were the national in-patient survey, national staff survey (for staff motivational engagement), and research activity (based on Trust size-corrected National Institute for Health Research records data). Spearman correlation analyses were conducted (minimum rho value 0.25, p-value<0.005), followed by principal component analysis (score cut-off 0.2). RESULTS: Initial correlation analyses identified eleven in-patient survey questions where better in-patient feedback was associated with increased clinical research activity, and only three questions linked with higher degree of staff motivational engagement. Subsequent principal component analysis confirmed that increased staff engagement is mainly linked to overall Trust performance such as staff levels, whereas staff in research-active hospitals provided in-patients with sufficient information - including on medication - and did well answering patient questions. CONCLUSIONS: Staff involvement in clinical research is associated with better patient feedback. Clear and thorough information provision to patients, may be a mechanism for improved patient outcomes including mortality.

Relationship between staff thriving, through engagement and research activity, and hospital-related outcome measures: A retrospective cross-sectional study.

INTRODUCTION AND OBJECTIVES: Both the standardised hospital mortality index (SHMI) and Care Quality Commission (CQC) ratings are used by the National Health Service (NHS) to monitor performance in English hospitals. We assessed if staff thriving, the concept of vitality and learning at work, through application of the surrogate measures engagement and research activity is associated with more favourable hospital performance outcomes. METHODS: This concerned a retrospective cross-sectional study using data for 129 English NHS hospital Trusts from the year 2019. Outcome measures were SHMI (linear regression, unstandardised coefficient beta) and CQC (binary logistic regression, odds ratio [OR]), whereas the independent variables considered were hospital location, degree of patient deprivation, research activity (drawn from National Institute for Health Research records and controlled for hospital size), and staff engagement scores (based on three survey questions corresponding to validated engagement factors). RESULTS: Staff engagement accounted for over half of the 13% variance R2 for the whole model related to improved CQC rating (OR 13.75, p-value 0.002). Increased research activity was associated with a lower SHMI score (unstandardized beta -0.024, p-value 0.007, R2 5% for each point change in research activity quotient), but independently from the higher SHMI seen for Northern hospital Trusts (beta 0.063, p-value 0.003, R2 11.6%). The degree of patient deprivation did not influence SHMI or CQC outcomes in the regression models. CONCLUSION: Increased staff thriving exhibits a modest, yet significantly, association with improved hospital performance; this was observed despite an underlying regional dichotomy in mortality rates.

Recommendations on Surveillance for Differentiated Thyroid Carcinoma in Children with PTEN Hamartoma Tumor Syndrome.

BACKGROUND: PTEN hamartoma tumor syndrome (PHTS) represents a group of syndromes caused by a mutation in the PTEN gene. Children with a germline PTEN mutation have an increased risk of developing differentiated thyroid carcinoma (DTC). Several guidelines have focused on thyroid surveillance in these children, but studies substantiating these recommendations are lacking. OBJECTIVE: The present study intends to provide the available evidence for a thyroid carcinoma surveillance program in children with PHTS. METHODS: An extensive literature search was performed to identify all studies on DTC in pediatric PHTS patients. Two pediatric cases are presented to illustrate the pros and cons of thyroid carcinoma surveillance. Recommendations for other patient groups at risk for DTC were evaluated. Consensus within the study team on recommendations for children with PHTS was reached by balancing the incidence and behavior of DTC with the pros and cons of thyroid surveillance, and the different surveillance methods. RESULTS: In 5 cohort studies the incidence of DTC in childhood ranged from 4 to 12%. In total 57 cases of DTC and/or benign nodular disease in pediatric PHTS patients were identified, of which 27 had proven DTC, with a median age of 12 years (range 4-17). Follicular thyroid carcinoma (FTC) was diagnosed in 52% of the pediatric DTC patients. No evidence was found for a different clinical behavior of DTC in PHTS patients compared to sporadic DTC. CONCLUSIONS: Children with PHTS are at increased risk for developing DTC, with 4 years being the youngest age reported at presentation and FTC being overrepresented. DTC in pediatric PHTS patients does not seem to be more aggressive than sporadic DTC. RECOMMENDATIONS: Surveillance for DTC in pediatric PHTS patients seems justified, as early diagnosis may decrease morbidity. Consensus within the study team was reached to recommend surveillance from the age of 10 years onwards, since at that age the incidence of DTC seems to reach 5%. Surveillance for DTC should consist of yearly neck palpation and triennial thyroid ultrasound. Surveillance in children with PHTS should be performed in a center of excellence for pediatric thyroid disease or PHTS.

Hospital Workforce Engagement and Inpatient Mortality Rate: Findings from the English National Health Service Staff Surveys.

BACKGROUND: Healthcare workforce engagement may represent a proactive approach against provider burnout, a widely prevalent condition that is associated with poor patient outcomes. OBJECTIVE: We examine whether workforce engagement is associated with better hospital performance, measured as lower inpatient mortality, in English National Health Services (NHS) acute Trusts. DESIGN: Panel study using cross-lagged regression, applying an optimally time-lagged value of the dependent variable as covariate to account for unmeasured Trust characteristics. PARTICIPANTS: NHS acute Trusts and respondents to the NHS Staff Surveys, 2012-2018. MAIN MEASURES: We measured engagement using three survey questions corresponding to validated engagement factors, and hospital performance using the Summary Hospital-level Mortality Indicator (SHMI). In the first analyses, associations of SHMI (dependent variable) with workforce engagement in the current, prior, and subsequent years were studied to find the optimum lag period for lagged regression analysis. In the subsequent cross-lagged regression analysis, bi-directional associations between SHMI and engagement were studied. Heterogeneity in engagement components across Trusts was studied in detail for the year 2017. KEY RESULTS: In the first analyses, current SHMI was negatively associated with engagement in the current year (ß = - 0.044; p = 0.035) more than with the prior year (ß = - 0.037; p = 0.049). In the second analysis, (a) engagement predicted same-year SHMI after controlling for prior-year SHMI (ß = - 0.044; p = 0.035). A 1-unit higher engagement score was associated with 4.4% lower SHMI. (b) SHMI predicted engagement in the same year (ß = - 0.066; p = 0.001) after controlling for prior-year engagement. More in-depth analysis showed high inter-trust heterogeneity on all three engagement factors (I2 > 85%). CONCLUSION: Higher workforce engagement predicts lower mortality which in turn predicts engagement. Heterogeneity in workforce well-being suggests an opportunity to foster mutual learning across Trusts.

Ferric carboxymaltose (Ferinject®) associated hypophosphataemia: case report illustrating the need for increased awareness to minimise incidence and risk.

Ferric carboxymaltose (Ferinject®) is an infusion administered for the treatment of iron deficiency anaemia. A number of previous case reports have shown the occurrence of hypophosphataemia after Ferinject® treatment, supposedly managed though high dose phosphate therapy. This case report highlights the risk associated with, and futility of, managing this adverse effect through high dose phosphate infusion. A review of the available literature suggests that if hypophosphataemia develops as a result of Ferinject®, through upregulation of the renal protein Fibroblast Growth Factor-23, it cannot be readily reversed and on average persists for circa 50 days. Acute medical units should be aware of this - likely underreported - adverse effect, and avoid treating these hypophosphataemic patients with high dose phosphate since it can compound symptoms.

Influence of maternal factors and mode of induction on labour outcomes: a pragmatic retrospective cohort study.

Since recent research indicates that other modalities are at a minimum non-inferior to the NICE-recommended hormonal agent prostaglandin E2 (PGE2), a retrospective cohort study was conducted on 1971 consecutively induced singleton pregnancies. Multinominal regression analysis showed that the odds ratio (OR) for vaginal delivery with balloon-mediated labour induction (84% vaginal deliveries; OR 1.6; 95% CI 0.7-3.5) is similar to the PGE2 agents propess (81%; OR 1.2; 95% CI 0.68-1.98) and prostin (79%; OR 0.99; 95% CI 0.55-1.79) when using a triple multi-agent induction as a reference. On the other hand, combining the propess and prostin (60% vaginal deliveries; OR 0.45; 95% CI 0.21-0.96) and attempting quadruple combinations of the induction modalities (56%; OR 0.37; 95% CI 0.16-0.85) yields significantly poorer outcomes. However, compared to the known factors associated with increased caesarean section rates, such as an increased maternal age, nulliparous pregnancies and a history of caesarean section, the differential impact of different induction modalities appear less pronounced. Impact statement What is already known on this subject? Recent published data from controlled clinical trials have shown that other labour-inducing agents, including balloon catheters, are as effective as prostaglandin E2 (PGE2) in achieving a vaginal delivery. What do the results of this study add? The data from this pragmatic retrospective cohort study supports the findings of others that the use of a balloon is as effective as PGE2. It also demonstrates that regular clinical practice can differ from an experimental environment, with patients receiving multiple induction modalities in a daily practice. Both the combination of different PGE2 medications and a quadruple labour induction approach are associated with poorer results, as measured by the vaginal delivery rate. The data presented here also confirms that a nulliparous status, a maternal age and a history of caesarean section are associated with reduced odds of achieving a vaginal delivery. What are the implications of these findings for clinical practice and/or further research? The body of evidence showing favourable results with a balloon induction is growing. Furthermore, there are limits to the effectiveness of combining the different induction modalities. Maternal and perinatal factors associated with a risk of caesarean section further complicate labour induction management.

The correlation between National Health Service trusts' clinical trial activity and both mortality rates and care quality commission ratings: a retrospective cross-sectional study.

OBJECTIVES: Evidence supporting the notion that clinical research activity in itself is of benefit to organisations as a whole is inconclusive. In the recent past, a positive association between research activity and reduced mortality has been shown. This study aimed to ascertain if clinical research activity is associated with established organisational outcome measures. STUDY DESIGN: Retrospective cross-sectional study. METHODS: For 129 English National Health Service hospital Trusts, National Institute for Health Research study activity data, Summary Hospital-level Mortality Indicator (SHMI) scores and Care Quality Commission (CQC) ratings were collected. Research activity was controlled for Trust size by dividing it by clinical staffing levels. Multiple linear regression and Spearman correlation analyses were performed. RESULTS: Although there is a significant association between the number of studies and participants with both SHMI score and CQC rating, one particular variable is correlated more significantly than others: the number of participants recruited into interventional studies. It shows a significant correlation with better CQC ratings (standardised coefficient beta 0.26, P-value 0.003) and lower SHMI scores (standardised coefficient beta -0.50, P-value 0.001). CONCLUSIONS: The mortality-related results corroborate with other published data showing a correlation between increased research and reduced deaths. Furthermore, there is also a statistically significant association between clinical trials activity and improved CQC ratings. However, these tie-ins are predominantly driven by the number of participants in interventional research rather than observational research activity.

NHS Trusts' clinical research activity and overall CQC performance - Is there a correlation?

OBJECTIVE: Since the late 2000's, the creation of the National Institute for Health Research (NIHR) has transformed clinical research activity in the United Kingdom. This study sought to establish if there is a link between clinical research activity and overall NHS Trust performance. STUDY DESIGN: Retrospective cohort study. METHODS: Data for NHS Trust performance were obtained from public databases, namely the Care Quality Commission (CQC) 2013 risk rating for overall performance, and 2012-13 NIHR records for clinical research activity. RESULTS: Applying Spearman's rank analysis, none of the Trust categories showed a correlation with CQC risk rating: small hospitals, r = -0.062 (P = 0.76; n = 27); medium, r = -0.224 (P = 0.13; n = 47); large, r = -0.008 (P = 0.96; n = 57); academic, r = -0.18 (P = 0.41; n = 24). Similar results were observed when CQC risk rating was compared with the number of different clinical research studies conducted per Trust. CONCLUSION: The degree of NIHR National Portfolio clinical research activity is not significantly related to CQC risk rating, used as an indicator of overall NHS Trust performance. Other studies have previously shown that increased research activity correlates with improved mortality rates, one component of CQC risk rating scores. Alternative tools may have to be explored to evaluate the impact of clinical research on NHS Trusts and its patients.

Physiological POSSUM as an indicator for long-term survival in vascular surgery.

OBJECTIVES: We investigated whether the POSSUM physiology score, originally designed as an indicator for 30-day mortality for comparative audit, could be used as an indicator of long-term survival in vascular surgery practice. METHODS: Data from 184 different vascular procedures conducted between 1989 and 2000, containing survival data for each patient of 10 years or longer, were analysed retrospectively. Parameters collected were the pre-operative physiological and the operative severity POSSUM score, gender, and type of procedure. Multivariate analyses were performed using Cox regression method and, on the basis of their physiological POSSUM score grouping, Kaplan-Meier analysis was performed for estimation of overall survival. RESULTS: Both an increase in physiological POSSUM score (hazard ratio [HR] 1.050, 95% confidence interval [CI] 1.031 to 1.070) and one of its components, age (HR 1.025, 95% CI 1.006 to 1.045; p = 0.009), were shown to be indicators of long-term all-cause mortality. The sample's mean physiological POSSUM score of 21 was then used as a cut-off point to categorise low and high-risk vascular surgery patients. Median survival in the low-risk group was 70 months (95% CI 56-86 months), whereas in the high-risk group this was 17 months (95% CI 3-31 months). CONCLUSION: The physiological POSSUM score, including patient age, is an indicator of long-term survival of patients with vascular disease. This may help in choosing the appropriate vascular intervention.

Evaluation of an alternative in vitro test battery for detecting reproductive toxicants.

The application of alternative methods in developmental and reproductive toxicology is challenging in view of the complexity of mechanisms involved. A battery of complementary test systems may provide a better prediction of developmental and reproductive toxicity than single assays. We tested twelve compounds with varying mechanisms of toxic action in an assay battery including 24 CALUX transcriptional activation assays, mouse cardiac embryonic stem cell test, ReProGlo assay, zebrafish embryotoxicity assay, and two CYP17 and two CYP19 activity assays. The battery correctly detected 11/12 compounds tested, with one false negative occurring, which could be explained by the absence of the specific mechanism of action of this compound in the battery. Toxicokinetic modeling revealed that toxic concentrations were in the range expected from in vivo reproductive toxicity data. This study illustrates added value of combining assays that contain complementary biological processes and mechanisms, increasing predictive value of the battery over individual assays.

Marked variation in venous thromboprophylaxis management for abdominal aortic aneurysm repair; results of survey amongst vascular surgeons in the United kingdom.

OBJECTIVES: We aimed to survey the current management of venous thromboprophylaxis in patients undergoing elective surgery for abdominal aortic aneurysm (AAA) by vascular surgeons in the United Kingdom. DESIGN: A questionnaire was designed to investigate anticoagulation strategies in the perioperative period of elective AAA repair, both open and endovascular. This included both chemical and mechanical prophylaxis. A total of 395 questionnaires was posted to the members of the Vascular Society of Great Britain and Ireland. RESULTS: One hundred and seventy-two (44%) valid responses were received. Half of the respondents administered pre-operative chemical prophylaxis at a mean of 13 h prior to AAA surgery. There was a high level of concordance in administration of heparin during surgery and in thromboprophylaxis post-operatively, with 97% giving some form of thromboprophylaxis. However there was a variation in the dose and timing, if administered, of chemical and mechanical prophylaxis. CONCLUSION: The survey revealed diversity in perioperative thromboprophylaxis strategies among vascular surgeons. This suggests that standardisation of pre-operative and post-operative mechanical and chemical thromboprophylaxis may be required which could potentially improve the outcomes in elective management of AAA in the UK.

Maternal and prenatal factors influencing the outcome of prostaglandin E2 induced labour.

In this retrospective cohort study involving 393 singleton pregnancies, we evaluated the maternal and prenatal factors influencing the use of and the outcome of prostaglandin E(2) (PGE(2)) induced labours. Only a nulliparous pregnancy was shown to be a significant predictor of the use of more than one dose of PGE(2) (odds ratio, OR 2.73, 95% confidence interval, CI 1.61-4.63). When the type of delivery was assessed, nulliparous status was significantly associated with a decreased chance of vaginal delivery (OR 0.12, 95% CI 0.045-0.32). Other variables that positively influence the chance of vaginal delivery include a mother's age being under 30 years (OR 2.63, 95% CI 1.51-4.58) and a single dose of PGE(2) (OR 2.86, 95% CI 1.21-6.79). Gestational age, fetal weight and maternal BMI have much less impact on PGE(2) use and chance of successful vaginal delivery than parity.

Prospective screening of patients with unexplained mental retardation using subtelomeric MLPA strongly increases the detection rate of cryptic unbalanced chromosomal rearrangements.

This study was designed to increase the diagnostic detection rate for subtelomeric unbalanced chromosomal rearrangements (UCRs) that are believed to cause 3-5% of all cases of mental retardation (MR), but often remain undetected by routine karyotyping because of limited resolution in light microscopy. Increased detection of such cryptic UCRs may be achieved by CGH- or SNP-array technology adapted for genome wide screening but these techniques are labor-intensive and expensive. We have implemented subtelomeric Multiplex Ligation-dependant Probe Amplification (MLPA), a relatively low cost and technically uncomplicated molecular approach, as a high throughput prospective screening tool for UCRs in MR patients. We prospectively studied a cohort of 466 MR patients and detected 53 aberrant MLPA signals. After exclusion of false-positives, potential familial polymorphisms and of non-cryptic UCRs also found in routine chromosome analysis, 18 cases or 3.9% of total could be confirmed as true cryptic subtelomeric UCRs. These were 6 terminal deletions, 8 unbalanced translocations, 3 Prader-Willi deletions and 1 subtelomeric interstitial deletion. This result increases our laboratory's detection rate in this patient cohort from 8.3% (without MLPA) to 12.2% (with MLPA), representing a 47% improvement. This study demonstrates that when applying MLPA in a routine cytogenetic diagnostic setting, a major increase of the diagnostic yield can be achieved.

Efficacy of in-feed medication with tylosin for the treatment and control of Mycoplasma hyopneumoniae infections.

The efficacy of in-feed medication with tylosin for the treatment of enzootic pneumonia was examined in an experimental Mycoplasma hyopneumoniae infection model. One group of 10 conventional M. hyopneumoniae-free pigs was inoculated intratracheally with a highly virulent field isolate of M. hyopneumoniae; a second group of 10 pigs was inoculated in the same way and after 12 days was given tylosin at 100 mg/kg feed for 21 days; a third group of 10 pigs was inoculated with sterile culture medium, and these pigs were not given tylosin. The pigs were examined daily for clinical signs and each pig was given a respiratory disease score. Thirty-three days after they had been infected the pigs were euthanased, the lung lesions were quantified and samples of lung were processed for immunofluorescence testing for M. hyopneumoniae. The mean (sd) respiratory disease and lung lesion scores were significantly higher (P<0.05) in both the infected groups than in the uninfected group. Between 23 and 33 days after infection the mean respiratory disease score of the pigs treated with tylosin was 0.54 (0.22), significantly (P<0.05) lower than that of the infected pigs which were left untreated, 1.54 (0.46); similarly, their average lung lesion score, 1.72 (1.20), was significantly lower than that of the untreated pigs, 5.27 (3.85).

Effect of monensin on blood ketone bodies, incidence and recurrence of disease and fertility in dairy cows.

Twelve trials designed to test the effect of monensin on milk production were carried out at eight different research farms. Data from these studies were evaluated for effects of monensin on health and reproduction. Monensin was added to the concentrate starting either 2 wk before (293 cows) or 5 wk after calving (601 cows) for periods ranging 16 to 37 wk. Applied after calving, the incidence of clinical mastitis was reduced in the monensin-treated animals. Monensin decreased the rate of intramammary infection (approximated by a change from below to above 250,000 somatic cells in milk) in first lactation heifers by 13%. Indicated by an adjusted incidence rate ratio of 0.58 (P = 0.03), the case incidence of noninfectious lameness decreased from 31% in control cows to 18% in cows receiving monensin before calving. The time from calving to first service was shorter for cows fed monensin before calving. Monensin reduced calving to conception intervals in cows with endometritis during the pretreatment period. No significant effects of monensin were observed for the duration of intra mammory infection (somatic cells in milk above 250,000), infectious lameness, endometritis, cystic ovarian disease, a summary category of 'other diseases,' times from calving to first observed estrus, and from first service to conception.

Effect of monensin on milk production of Holstein-Friesian dairy cows.

We examined the effects of monensin on feed intake and milk production in Holstein-Friesian cows receiving a total mixed rations in two experiments. In experiment 1, 60 individually fed cows consumed, during wk 7 to 26 of lactation, 1 kg/d of supplement containing either 0, 150,300, or 450 mg of monensin. In experiment 2, 98 group-fed cows also received 1 kg/d of a supplement with either 0 or 300 mg/d of monensin for two consecutive lactations. In lactations 1 and 2, treatment started at wk 8 and 3 wk prior to calving, and continued for 32 wk. In experiment 1, 150, 300, and 450 mg of monensin/d produced a small decrease in feed intake and milk yield responses of 2.8, 2.5 and 1.5 kg/d, respectively. In experiment 2, milk yield responses of 0.8 and 1.1 kg/d were recorded in lactations 1 and 2. Milk fat and milk protein content declined in experiments 1 and 2, lactations 1 and 2 by 0.46, 0.38 and 0.27%, and 0.16, 0.16 and 0.11%, respectively. Yield of milk constituents was unaffected. Efficiency of milk production was increased by 5% in experiment 1. In experiment 2, lactation 2, monensin decreased beta-hydroxybutyrate and acetoacetate but increased blood glucose concentration.

Effect of monensin on milk production by Holstein and Jersey cows.

Effects of the administration of monensin via concentrates to dairy cows were studied in two trials. In one trial, 64 Holstein cows were assigned to four groups that received 0, 150, 300, or 450 mg/d of monensin from 5 to 24 wk postpartum. Milk production tended to increase (4.0, 3.3, and 5.4%, respectively) for the three groups of treated cows. Fat content was decreased by 0.09, 1.89, and 4.09 g/kg, respectively, for these same three groups. The effect on protein content was small and nonsignificant. Feed intake was reduced in treated cows, although not significantly, and feed efficiency was improved by monensin. In a confirmatory trial, 58 Holstein and 22 Jersey cows were allocated either to a control group or to a treatment group that received 300 mg/d of monensin from 5 to 36 wk postpartum during the first lactation and from 2 wk before calving to 36 wk postpartum during a subsequent lactation. During the first lactation, cows in the treatment group showed a 7% increase in milk production, a relative decrease (1.4 g/kg) in milk fat content, and equal protein content compared with cows in the control group. Body weight gain and body condition scores near the end of the treatment period were higher for cows in the treatment group. A decrease in blood ketone concentrations was found between 7 and 56 d of lactation. Treatment effects on milk production differed between breeds and within genetic lines. Jersey cows were less responsive than were Holstein cows, and Holstein cows with a high ratio of breeding values for protein and fat showed larger milk production responses. Results from the second lactation showed similar differences between the two groups as did those from the first lactation.

Effects of treatment of dairy cows with recombinant bovine somatotropin over three or four lactations.

Jersey, Dutch Red and White, and Friesian cows were subcutaneously injected with 640 mg of recombinant bST at 28-d intervals from 87 to 115 d after calving through four successive lactations. A TMR (6.72 MJ of NEL) and 168 g of CP/kg of DM) was fed for ad libitum consumption. The bST effects per day were 3.3 kg for milk yield, 189 g for fat yield, 109 g for protein yield, 157 g for lactose yield, 4 MJ of NEL for feed intake, and -4 kg for body weight. Responses in blood parameters measured 7 d after injection were -.007 mmol/L for glucose, -1.3 mg of N/100 ml for urea, 221 mumol/L for 3-hydroxybutyrate, 59 mumol/L for NEFA, 65 ng/L for insulin, 2.8 micrograms/L for thyroxine, and 26.7 micrograms/L for somatotropin. Somatic cell count in milk was 75,000 cells/ml higher in treated cows. Concentrations of NEFA, Ca, Mg, and phosphorus were unaffected. Repeatability of the maximum response in milk yield after bST treatment was low: .2 within and .5 between lactations. Cows treated in the previous lactation had slightly more retained placentas, and birth weight of their calves was 2 kg less. No differences were observed between treated and control cows in disease incidence. Six treated cows were culled in third and fourth lactations. No indications for tissue damage, inflammation, or stress after bST injections were detected.