Early Repair of Rib Fractures Is Associated with Superior Length of Stay and Total Hospital Cost: A Propensity Matched Analysis of the National Inpatient Sample

Background and Objectives: Previous studies have suggested that early scheduling of the surgical stabilization of rib fractures (SSRF) is associated with superior outcomes. It is unclear if these data are reproducible at other institutions. We hypothesized that early SSRF would be associated with decreased morbidity, length of stay, and total charges. Materials and Methods: Adult patients who underwent SSRF for multiple rib fractures or flail chest were identified in the National Inpatient Sample (NIS) by ICD-10 code from the fourth quarter of 2015 to 2016. Patients were excluded for traumatic brain injury and missing study variables. Procedures occurring after hospital day 10 were excluded to remove possible confounding. Early fixation was defined as procedures which occurred on hospital day 0 or 1, and late fixation was defined as procedures which occurred on hospital days 2 through 10. The primary outcome was a composite outcome of death, pneumonia, tracheostomy, or discharge to a short-term hospital, as determined by NIS coding. Secondary outcomes were length of hospitalization (LOS) and total cost. Chi-square and Wilcoxon rank-sum testing were performed to determine differences in outcomes between the groups. One-to-one propensity matching was performed using covariates known to affect the outcome of rib fractures. Stuart-Maxwell marginal homogeneity and Wilcoxon signed rank matched pair testing was performed on the propensity-matched cohort. Results: Of the 474 patients who met the inclusion criteria, 148 (31.2%) received early repair and 326 (68.8%) received late repair. In unmatched analysis, the composite adverse outcome was lower among early fixation (16.2% vs. 40.2%, p < 0.001), total hospital cost was less (USD114k vs. USD215k, p < 0.001), and length of stay was shorter (6 days vs. 12 days) among early SSRF patients. Propensity matching identified 131 matched pairs of early and late SSRF. Composite adverse outcomes were less common among early SSRF (18.3% vs. 32.8%, p = 0.011). The LOS was shorter among early SSRF (6 days vs. 10 days, p < 0.001), and total hospital cost was also lower among early SSRF patients (USD118k vs. USD183k late, p = 0.001). Conclusion: In a large administrative database, early SSRF was associated with reduced adverse outcomes, as well as improved hospital length of stay and total cost. These data corroborate other research and suggest that early SSRF is preferred. Studies of outcomes after SSRF should stratify analyses by timing of procedure.

Age as a Barrier to Surgical Stabilization of Rib Fractures in Patients with Flail Chest

INTRODUCTION

Although randomized trials demonstrate a benefit to surgical stabilization of rib fractures (SSRF), SSRF is rarely performed. We hypothesized older patients were less likely to receive SSRF nationally.

METHODS

The 2016 National Inpatient Sample was used to identify adults with flail chest. Comorbidities and receipt of SSRF were categorized by ICD-10 code. Univariable testing and Multivariable regression were performed to determine the association of demographic characteristics and comorbidities to receipt of SSRF.

RESULTS

1021 patients with flail chest were identified, including 244 (23.9%) who received SSRF. Patients ≥70 years were less likely to receive SSRF. (<70 yrs 201/774 [26.0%] vs ≥70 43/247 [17.4%], P = .006) and had higher risk of death (<70 yrs 39/774 [5.0%] vs ≥70 33/247 [13.4%], P < .001) In multivariable modeling, only age ≥70 years was associated with SSRF (OR .591, P = .005).

CONCLUSION

Despite guideline-based support of SSRF in flail chest, SSRF is performed in <25% of patients. Age ≥70 years is associated with lower rate of SSRF and higher risk of death. Future study should examine barriers to SSRF in older patients.

Iatrogenic rib fractures and the associated risks of mortality

PURPOSE

Rib fractures, though typically associated with blunt trauma, can also result from complications of medical or surgical care, including cardiopulmonary resuscitation. The purpose of this study is to describe the demographics and outcomes of iatrogenic rib fractures.

METHODS

Patients with rib fractures were identified in the 2016 National Inpatient Sample. Mechanism of injury was defined as blunt traumatic rib fracture (BTRF) or iatrogenic rib fracture (IRF). IRF was identified as fractures from the following mechanisms: complications of care, drowning, suffocation, and poisoning. Differences between BTRF and IRF were compared using rank-sum test, Chi-square test, and multivariable regression.

RESULTS

34,644 patients were identified: 33,464 BTRF and 1180 IRF. IRF patients were older and had higher rates of many comorbid medical disorders. IRF patients were more likely to have flail chest (6.1% versus 3.1%, p < 0.001). IRF patients were more likely to have in-hospital death (20.7% versus 4.2%, p < 0.001) and longer length of hospitalization (11.8 versus 6.9 days, p < 0.001). IRF patients had higher rates of tracheostomy (30.2% versus 9.1%, p < 0.001). In a multivariable logistic regression of all rib fractures, IRF was independently associated with death (OR 3.13, p < 0.001). A propensity matched analysis of IRF and BTRF groups corroborated these findings.

CONCLUSION

IRF injuries are sustained in a subset of extremely ill patients. Relative to BTRF, IRF is associated with greater mortality and other adverse outcomes. This population is understudied. The etiology of worse outcomes in IRF compared to BTRF is unclear. Further study of this population could address this disparity.

Surgery following neoadjuvant chemoradiation therapy in clinical N3 esophageal cancer results in improved survival: a propensity-matched analysis

Esophageal cancer patients with extensive nodal metastases have poor survival, and benefit of surgery in this population is unclear. The aim of this study is to determine if surgery after neoadjuvant chemoradiotherapy (nCRT) improves overall survival (OS) in patients with clinical N3 (cN3) esophageal cancer relative to chemoradiation therapy (CRT) alone. The National Cancer Database was queried for all patients with cN3 esophageal cancer between 2010 and 2016. Patients who met inclusion criteria (received multiagent chemotherapy and radiation dose ≥30 Gy) were divided into two cohorts: CRT alone and nCRT + surgery. 769 patients met inclusion criteria, including 560 patients who received CRT alone, and 209 patients who received nCRT + surgery. The overall 5-year survival was significantly lower in the CRT alone group compared to the nCRT + surgery group (11.8% vs 18.0%, P < 0.001). A 1:1 propensity matched cohort of CRT alone and nCRT + surgery patients also demonstrated improved survival associated with surgery (13.11 mo vs 23.1 mo, P < 0.001). Predictors of survival were analyzed in the surgery cohort, and demonstrated that lymphovascular invasion was associated with worse survival (HR 2.07, P = 0.004). Despite poor outcomes of patients with advanced nodal metastases, nCRT + surgery is associated with improved OS. Of those with cN3 disease, only 27% underwent esophagectomy. Given the improved OS, patients with advanced nodal disease should be considered for surgery. Further investigation is warranted to determine which patients with cN3 disease would benefit most from esophagectomy, as 5-year survival remains low (18.0%).

Traffic stops do not prevent traffic deaths

OBJECTIVES

Amid growing calls for police reform, it is imperative to reassess whether police actions designed to improve public safety are associated with injury prevention. This study aims to examine the relationship between the police traffic stops (PTSs) and motor vehicle crash (MVC) deaths at the state level. We hypothesize that increased PTSs would be associated with reduced MVC deaths.

METHODS

We retrospectively analyzed PTSs and MVC deaths at the state level from 2004 to 2016. Police traffic stops data were from 33 state patrols from the Stanford Open Policing Project. The MVC deaths data were collected from the National Highway Traffic Safety Administration. The vehicle miles traveled data were from the Federal Highway Administration Office of Highway Policy Information. All data were adjusted per 100 million vehicle miles traveled (100MVMT) and were analyzed as state-level time series cross-sectional data. The dependent variable was MVC deaths per 100MVMT, and the independent variable was number of PTSs per 100MVMT. We performed panel data analysis accounting for random and fixed state effects and changes over time.

RESULTS

Thirty-three state patrols with 235 combined years were analyzed, with a total of 161,153,248 PTSs. The PTS rate varied by state and year. Nebraska had the highest PTS rate (3,637/100MVMT in 2004), while Arizona had the lowest (0.17/100MVMT in 2009). Motor vehicle crash deaths varied by state and year, with the highest death rate occurring in South Carolina in 2005 (2.2/100MVMT) and the lowest in Rhode Island in 2015 (0.57/100MVMT). After accounting for year and state-level variability, no association was found between PTS and the MVC death rates.

CONCLUSION

State patrol traffic stops are not associated with reduced MVC deaths. Strategies to reduce death from MVC should consider alternative strategies, such as motor vehicle modifications, community-based safety initiatives, improved access to health care, or prioritizing trauma system.

LEVEL OF EVIDENCE

Retrospective epidemiological study, level IV.

Robotic approach has improved outcomes for minimally invasive resection of mediastinal tumors

BACKGROUND

The optimal minimally invasive surgical (MIS) approach to mediastinal tumors is unknown. There are limited reports comparing the outcomes of resection with robotic-assisted and video-assisted thoracoscopy (RATS vs VATS). We hypothesized that patients who underwent RATS would have improved outcomes.

METHODS

The National Cancer Database was queried for all patients who underwent MIS for any mediastinal tumor from 2010-2016. Patients were determined to have an adverse composite outcome if they had any of the adverse perioperative outcomes; conversion to open procedure, 90-day mortality, 30-day readmission, and positive pathologic margins. Secondary outcomes of interest were length-of-stay (LOS) and overall survival. Multivariable logistic regression was used to assess likelihood of having a composite adverse outcome based on surgical approach.

RESULTS

856 patients were included: 402 (47%) underwent VATS and 454 (53%) underwent RATS. RATS resections were associated with fewer conversions (4.9% vs 14.7%, p<0.001), fewer positive margins (24.3% vs 31.6%, p=0.02), shorter LOS (3.8d vs 4.3d, p=0.01) and less composite adverse events (36.7% vs 51.3%, p<0.001). Multivariate analysis showed RATS (OR 0.44, p<0.001) was independently associated with decreased likelihood of composite adverse outcome, even among tumors >4 cm (OR 0.45, p=0.001). Overall survival was similar between the two groups.

CONCLUSIONS

Among patients who underwent MIS for a mediastinal tumor, RATS had fewer adverse outcomes than VATS, even for tumors ≥4 cm. These data suggests that RATS may be the preferred technique for patients who are candidates for minimally invasive resection of mediastinal tumors.

Palliative Surgery Outcomes for Patients with Esophageal Cancer: An NCDB Analysis

INTRODUCTION

Many patients with esophageal cancer are not candidates for surgical resection with curative intent, given the advanced stage of disease at presentation. Palliative surgery is one treatment option, but relative survival of palliative surgery has not been described. This study aims to describe the outcomes of palliative surgery in patients with esophageal cancer.

METHODS

We used the National Cancer Database to identify patients with esophageal cancer who received palliative surgery or non-surgical palliation-which consisted of palliative radiation and palliative chemotherapy without any surgery. The outcome of interest was overall survival. Characteristics of patients were compared between the palliative surgery group and the non-surgical group using rank sum test or chi square test. Survival differences between groups were compared using Kaplan Meier estimate and log rank test, and Cox proportional hazards model.

RESULTS

A total of 14,589 patients were included in the analysis, including 2,812 (19.2%) receiving palliative surgery and 11,777 (80.7%) receiving non-surgical palliation (6,512 palliative radiation and 5,265 palliative chemotherapy). Median overall survival in palliative surgery patients was 5.5 mo, shorter than non-surgical palliation (6.4 mo, P = 0.004). However, when correcting for age, sex, nodal status, metastases, Charlson score, histology, academic center, and private insurance, there was no difference in survival between palliative surgery and non-surgical palliation in Cox proportional hazard modeling (HR 1.03 (0.975-1.090), P = 0.281).

CONCLUSIONS

Palliative surgery in advanced esophageal cancer is associated with poor overall survival but is similar to other palliative modalities. Palliative Surgery for esophageal cancer patients should be used sparingly given these poor outcomes.

Should Rib Fracture Patients be Treated at High Acuity Trauma Hospitals?

BACKGROUND

It is well known that severely injured trauma patients have better outcomes when treated at centers that routinely treat high acuity trauma. The benefits of specialty treatment for chest trauma have not been shown. We hypothesized that patients with high risk rib fractures treated in centers that care for high acuity trauma would have better outcomes than patients treated in other centers.

METHODS

All rib fracture patients were identified via the 2016 National Inpatient Sample using ICD-10 codes; Abbreviated Injury Scales (AIS) and Elixhauser comorbidity scores were also extracted. Chest AIS was grouped as mild (≤ 1) or severe (≥ 2). All patients with AIS > 2 in another body region were excluded. High acuity trauma hospitals (TH) were defined as hospitals which transferred 0% of neurotrauma patients; all other hospitals were defined as non-trauma hospitals. Poor outcome was defined as any patient who died, had a tracheostomy, developed pneumonia, or had a length of stay in the longest decile. Logistic regression with an interaction term for hospital type and chest trauma severity was performed.

RESULTS

A total of 29,780 patients with rib fractures were identified (median age 64 (IQR 51-79), 60% male), of whom 22% had poor outcomes. Fifty-three percent of patients were treated at non-trauma hospitals. In unadjusted comparisons, poor outcomes occurred more often at TH (22.4% versus 21.4%, P = 0.03). However, after adjustment, severe chest trauma that was treated at non-trauma hospitals was associated with higher odds of poor outcomes (OR 1.6, < 0.001).

DISCUSSION

More than 20% of patients with severe chest trauma have a poor outcome. Severe chest trauma outcomes are improved at TH. Development of transfer criteria for chest injuries in high-risk patients may mitigate poor outcomes at hospitals without specialized trauma expertise.

Concurrent diagnosis of anxiety increases postoperative length of stay among patients receiving esophagectomy for esophageal cancer

OBJECTIVE

Psychiatric comorbidities disproportionately affect patients with cancer. While identified risk factors for prolonged length of stay (LOS) after esophagectomy are primarily medical comorbidities, the impact of psychiatric comorbidities on perioperative outcomes is unclear. We hypothesized that psychiatric comorbidities would prolong LOS in patients with esophageal cancer.

METHODS

The 2016 National Inpatient Sample (NIS) was used to identify patients with esophageal cancer receiving esophagectomy. Concurrent psychiatric illness was categorized using Clinical Classifications Software Refined for ICD-10, creating 34 psychiatric diagnosis groups (PDGs). Only PDGs with >1% prevalence in the cohort were included in the analysis. The outcome of interest was hospital LOS. Bivariable testing was performed to determine the association of PDGs and demographic factors on LOS using rank sum test. Multivariable regression analysis was performed using backward selection from bivariable testing (α ≤ 0.05).

RESULTS

We identified 1,730 patients who underwent esophagectomy for esophageal cancer in the 2016 NIS. The median LOS was 8 days (IQR 5-12). In bivariable testing, a concurrent diagnosis of anxiety was the only PDG associated with LOS (9 days (IQR 6-14) with anxiety diagnosis versus 8 days (IQR 5-12) with no anxiety diagnosis, p = 0.022). Multivariable modeling showed an independent association between anxiety diagnosis and increased LOS (OR 4.82 (1.25-25.23), p = 0.022). Anxiety was not associated with increased hospital cost or in-hospital mortality.

CONCLUSIONS

This analysis demonstrates an independent effect of anxiety prolonging postoperative LOS after esophagectomy in the United States. These findings may influence perioperative care, patient expectations, and resource allocation.

Wedge Resection Offers Similar Survival to Segmentectomy for Typical Carcinoid Tumors

Current guidelines recommend anatomic lung resection of typical bronchopulmonary carcinoids. Typical carcinoid tumors have excellent prognosis and sublobar resection has been associated with noninferior long-term survival. It's unclear whether wedge resection is acceptable for small typical carcinoid tumors. We hypothesize there is no difference in survival between wedge resection and segmentectomy for Stage I typical bronchopulmonary carcinoid tumors. Using the National Cancer Database from 2010 to 2016, we identified clinical T1N0M0 typical bronchopulmonary carcinoid tumors by wedge resection or segmentectomy. Short-term outcomes included length of stay, lymph nodes evaluated, pathologic node status, positive margin status, and 90-day mortality. Primary outcome was overall survival and estimated using Kaplan-Meier survival analysis. 821 patients were identified: 677 receiving wedge resection, 144 receiving segmentectomy. Segmentectomy was more commonly performed in an academic setting (70.0% vs 57.3%, P = 0.005). The mean tumor size for segmentectomy was 1.7 cm versus 1.4 cm for wedge resection (P < 0.001). There was no difference in LOS, positive margin status, and 90-day mortality between groups. There were significantly more lymph nodes evaluated in segmentectomy patients (median 4 vs 0, P < 0.001), but there was no difference in positive lymph node status (5.3% vs 2.6%, P = 0.165). The OS was similar between wedge and segmental resection (P = 0.613): 3-year survival (93.5% vs 92.8%) and 5-year survival (83.8% vs 84.9%). Wedge resection and segmentectomy have similar survival for Stage I typical bronchopulmonary carcinoids in a large national database. This analysis suggests nonanatomic, parenchymal-sparing resection should be considered an appropriate alternative for Stage I typical bronchopulmonary carcinoids.

Does Timing of Robotic Esophagectomy Adoption Impact Short-Term Postoperative Outcomes?

BACKGROUND

Robotic esophagectomies are increasingly common and are reported to have superior outcomes compared with an open approach; however, it is unclear if all institutions can achieve such outcomes. We hypothesize that early adopters of robotic technique would have improved short-term outcomes.

METHODS

The National Cancer Database (2010-2016) was used to identify robotic esophagectomies. Early adopters were defined as programs which performed robotic esophagectomies in 2010-2011, late adopters in 2012-2013. Outcomes of esophagectomies performed between 2014 and 2016 were compared and included length of stay, number of lymph nodes evaluated, readmission, conversion rate, and 90-day mortality. Multivariable regressions, accounting for robotic esophagectomy volume, were used to control for confounding factors.

RESULTS

There were 37 early adopters and 35 late adopters. Between 2014 and 2016, 683 robotic esophagectomies were performed: 446 (65.3%) by early adopters and 237 (34.7%) by late adopters. Early adopters were more likely to be academic programs (96.2 versus 72.8%, P < 0.01). Other clinical and demographic variables were similar. Late adopters were found to have decreased a number of lymph nodes evaluated (coefficient -2.407, P = 0.004) compared with early adopters. There were no significant differences in length of stay, readmissions, rate of positive margins, conversion from robotic to open, or 90-day mortality.

CONCLUSIONS

When accounting for robotic esophagectomy volume, late adoption of robotic esophagectomy was associated with a reduced lymph node harvest, but other postoperative outcomes were similar. These data suggest that programs can safely start new robotic esophagectomy programs, but must ensure an adequate case load.

Robotic minimally invasive esophagectomy provides superior surgical resection

INTRODUCTION

Robotic minimally invasive esophagectomy (RMIE) and "traditional" minimally invasive esophagectomy techniques (tMIE) have reported superior outcomes relative to open techniques. Differences in the outcomes of these two approaches have not been examined. We hypothesized that short-term outcomes of RMIE would be superior to tMIE.

METHODS AND PROCEDURES

The National Cancer Database was used to analyze outcomes of patients undergoing RMIE and tMIE from 2010 to 2016. Patients with clinical metastatic disease were excluded. Trends in the number of procedures performed with each approach were described using linear regression testing. Primary outcome of interest was 90-day mortality rate. Secondary outcomes of interest were positive surgical margin rate, number of lymph nodes (LN) removed, adequate lymphadenectomy (> 15 LNs), length of hospitalization (LOS), readmission rate, and conversion to open rate. Outcomes of RMIE and tMIE were compared using Wilcoxon rank sum test and chi square test as appropriate. Multivariable regression was also performed to reduce the impact of differences in the cohorts of patients receiving RMIE and tMIE.

RESULTS

6661 minimally invasive esophagectomies were performed from 2010 to 2016 (1543/6661 (23.2%) RMIE and 5118/6661 (76.8%) tMIE). Over the study period, the proportion of RMIE increased from 10.4% (64/618) in 2010 to 27.2% (331/1216) in 2016 (p < 0.001) (Fig. 1). The primary outcome of 90-day mortality was similar between RMIE and tMIE (92/1170 (7.4%) vs 305/4148 (7.9%), p = 0.558) (Table 2). RMIE and tMIE also had similar readmission rate (6.3 vs 7%, p = 0.380). There was no difference between the cohorts based on sex, age, race, insurance, and tumor size. The cohorts of patients receiving RMIE and tMIE differed in that RMIE patients had lower rates of elevated Charlson scores, were more likely to be treated at an academic institution, had a higher rate of advanced clinical T-stage and clinical nodal involvement, and had received neoadjuvant therapy. In a univariate analysis, RMIE had a lower rate of positive margin (3.9 vs 6.1%, p = 0.001), more mean lymph nodes evaluated (16.6 ± 9.74 vs 16.1 ± 10.08 p = 0.018), lower conversion to open rate (5.4 vs 11.4%, p < 0.001), and a shorter mean length of stay (12.1 ± 10.39 vs 12.8 ± 11.18 days, p < 0.001). In multivariable analysis, RMIE was associated with lower risk of conversion to open (OR 0.51, 95% CI: 0.37-0.70, p < 0.001) and lower rate of positive margin (OR 0.62, 95% CI: 0.41-0.93, p = 0.021).). Additionally, in a multivariable logistic regression, RMIE demonstrated superior adequate lymphadenectomy (> 15 LNs) (OR 1.18, 95% CI 1.02-1.37, p < 0.032).

CONCLUSION

In the National Cancer Database, robotic esophagectomy is associated with superior rate of conversion to open and positive surgical margin status. We speculate enhanced dexterity and visualization of RMIE facilitates intraoperative performance leading to improvement in these outcomes.

Minimally invasive esophagectomy is associated with superior survival, lymphadenectomy and surgical margins: propensity matched analysis of the National Cancer Database

Despite excellent short-term outcomes of minimally invasive esophagectomy (MIE), there is minimal data on long-term outcomes compared to open esophagectomy. MIE's superior visualization may have improved lymphadenectomy and complete resection rate and therefore improved long-term outcomes. We hypothesized that MIE would have superior long-term survival. Patients undergoing an esophagectomy for cancer between 2010 and 2016 were identified in the National Cancer Database. MIE included laparoscopic/robotic approach, and conversions were categorized as open. A 1:1 propensity match was performed. Lymphadenectomy and margin status were compared between MIE and open using Stuart Maxwell marginal homogeneity and Wilcoxon matched-pair signed-rank test. Survival was compared using log-rank test. 13,083 patients were identified: 8,906 (68%) open and 4,177 (32%) MIE. Propensity matching identified 3,659 'pairs' of MIE and open esophagectomy patients. Among them, MIE was associated with higher number lymph nodes examined (16 vs. 14, P < 0.001) and similar number of positive lymph nodes (0 vs. 0, P = 0.33). MIE had higher rate of negative pathologic margin (95 vs. 93.5%, P < 0.001). MIE was also associated with shorter hospitalization (9 vs. 10 days, P < 0.001). Survival was improved among MIE patients (46.6 vs. 41.4 months for open, P = 0.003) and among pathologic node-negative patients (71.4 vs. 61.5 months, P = 0.005). These data suggest that MIE has improved short-term outcomes (improved lymphadenectomy, pathologic margins, and length of stay) and also associated improved overall survival. The etiology of superior overall survival is likely secondary to many factors related and unrelated to surgical approach.

Outcomes of robotic esophagectomies for esophageal cancer by hospital volume: an analysis of the national cancer database

BACKGROUND

Robotic minimally invasive esophagectomies (RMIE) have been associated with superior outcomes; however, it is unclear if these are specific to robotic technique or are present only at high-volume institutions. We hypothesize that low-volume RMIE centers would have inferior outcomes.

METHODS

The National Cancer Database (NCDB) identified patients receiving RMIE from 2010 to 2016. Based on the total number of RMIE performed by each hospital system, the lowest quartile performed ≤ 9 RMIE over the study period. Ninety-day mortality, number of lymph nodes evaluated, margins status, unplanned readmissions, length of stay (LOS), and overall survival were compared. Regression models were used to account for confounding.

RESULTS

1565 robotic esophagectomies were performed by 212 institutions. 173 hospitals performed ≤ 9 RMIE (totaling 478 operations over the study period, 30.5% of RMIE) and 39 hospitals performed > 9 RMIE (1087 operations, 69.5%). Hospitals performing > 9 RMIE were more likely to be academic centers (90.4% vs 66.2%, p < 0.001), have patients with advanced tumor stage (65.3% vs 59.8%, p = 0.049), andadministered preoperative radiation (72.8% vs 66.3%, p = 0.010). There were no differences based on demographics, nodal stage, or usage of preoperative chemotherapy. On multivariable regressions, hospitals performing ≤ 9 RMIE were associated with a greater likelihood of experiencing a 90-day mortality, a reduced number of lymph nodes evaluated, and a longer LOS; however, there was no association with rates of positive margins or unplanned readmissions. Median overall survival was decreased at institutions performing ≤ 9 RMIE (37.3 vs 51.5 months, p < 0.001). Multivariable Cox regression demonstrated an association with poor survival comparing hospitals performing ≤ 9 to > 9 RMIE (HR 1.327, p = 0.018).

CONCLUSION

Many robotic esophagectomies occur at institutions which performed relatively few RMIE and were associated with inferior short- and long-term outcomes. These data argue for regionalization of robotic esophagectomies or enhanced training in lower volume hospitals.

Conversion from thoracoscopic to open pneumonectomy is not associated with short- or long-term mortality

BACKGROUND

Thoracoscopic pneumonectomy commonly requires conversion to thoracotomy. We hypothesize that conversion would lead to worse short- and long-term outcomes compared with operations completed thoracoscopically.

METHODS

The National Cancer Database identified patients who underwent a pneumonectomy from 2010 to 2016. Trends in conversion were described using linear regression. Multivariable regression of factors associated with conversion was performed. Short-term outcomes included duration of stay, number of lymph nodes harvested, margin status, readmission, and 90-day mortality. Long-term outcome was evaluated as overall survival.

RESULTS

A total of 8,037 patients underwent a pneumonectomy. The rate of attempted thoracoscopic pneumonectomies increased from 11% to 22% (P < .001) and the rate of conversion decreased from 39% to 33% (P = .011). On multivariable analysis, a greater patient comorbidity index and pathologic nodal-stage 2 disease were associated with an increased rate of conversion. The mean number of lymph nodes evaluated was greater as was the duration of stay in the conversion group, but conversion to open thoracotomy was not associated with positive surgical margins, readmission rate, 90-day mortality, or survival.

CONCLUSION

Thoracoscopic pneumonectomy is performed with increasing frequency and decreasing conversion rate. Conversion is associated with a greater duration of stay but other short- and long-term outcomes are similar. This observation suggests minimal harm in conversion from minimally invasive to open pneumonectomy.

Evaluating the Effect of Margin Consensus Guideline Publication on Operative Patterns and Financial Impact of Breast Cancer Operation

BACKGROUND

This study sought to evaluate re-excision rates, patient satisfaction with their breasts, and healthcare costs before and after publication of 2014 Society of Surgical Oncology/American Society of Radiation Oncology consensus guideline on margins for breast conserving operation with whole-breast irradiation for stage I and II breast cancer at an academic institution.

STUDY DESIGN

Patients with stage I and II invasive carcinomas who underwent partial mastectomy were divided into 2 groups based on whether they were treated before (PRE) or after (POST) guideline publication in March 2014. Groups were compared with respect to re-excision rates, conversion to mastectomy, specimen volumes, mean cost per patient of surgical care, and prospectively collected patient post-procedure quality of life.

RESULTS

A total of 237 patients who underwent partial mastectomy were examined (n = 126 in the PRE group and n = 111 in the POST group). Patients in the POST group were less likely to require re-excision (9% POST vs 37% PRE; p < 0.001) and were less likely to undergo conversion to mastectomy (5% POST vs 14% PRE; p = 0.02). After consensus guideline publication, mean operative cost per patient decreased ($4,874 POST vs $5,772 PRE; p < 0.001), and patients had improved breast quality of life scores (77 out of 100 POST vs 61 out of 100 PRE; p = 0.03). On multivariable analysis, publication of the consensus statement was an independent predictor of decreased re-excision rates (odds ratio 0.17; 95% CI 0.08 to 0.38; p < 0.001) and operative cost per patient (odds ratio 0.14; 95% CI 0.78 to 0.30; p < 0.001).

CONCLUSIONS

Widespread implementation of the consensus guideline on margins for breast conserving operation will likely lead to the intended improvements in operative and financial outcomes, as well as patient satisfaction with breast conserving operation.

Short communication: Effect of estrogen supplemented at dry-off on temporal changes in concentrations of lactose in blood plasma of Holstein cows

The objective was to determine the effect of supplemental estrogen (estradiol cypionate, ECP) at dry-off on temporal changes in concentrations of lactose in blood plasma of Holstein cows as an indicator of rate of mammary involution. Thirty-two Holstein cows (8/group) were assigned randomly to 4 treatment groups: 30-d dry, 30-d dry + ECP, 60-d dry, and 60-d dry + ECP. A single injection (7.5 mL) of cottonseed oil (30- and 60-d dry) or ECP (15 mg) in oil (30- and 60-d dry + ECP) was administered intramuscularly at dry-off. Blood samples were collected from the coccygeal vein of all cows 24 h before dry-off and at dry-off, and then 8 samples were collected throughout the subsequent 48 h to monitor concentrations of lactose in blood plasma. No significant effects of ECP on the overall mean concentrations of lactose were detected. Concentrations of lactose increased and were greatest in blood collected 20 h (520.4 +/- 54.1, 268.1 +/- 48.2, 345.0 +/- 52.3, 418.4 +/- 49.8 microM, for the 4 treatment groups respective to the order listed above) after supplemental ECP and final milk removal. At 40 h, concentrations approached those observed 24 h before dry-off (140.5 +/- 52.1, 57.6 +/- 47.1, 90.1 +/- 51.4, 61.2 +/- 48.4 microM, respectively). Concentrations of lactose at 20 h were positively correlated with milk yield of cows at dry-off. Similar temporal profiles of lactose in blood plasma of cows supplemented or not with ECP indicated that ECP at dry-off did not markedly alter the course of tight junction leakage that typically occurs in mammary epithelial tissue during progressive early involution when milk removal is discontinued.

Milk Production from Holstein Half Udders After Concurrent Thirty- and Seventy-Day Dry Periods,

The objective of this study was to use a within-cow, half-udder model to compare the effect of cessation of milk removal from mammary quarters within respective half udders at either 30 or 70 d before expected calving date (ECD) on the ability of the half udders to subsequently produce milk. Pregnant Holstein cows were assigned to control (n = 14) or treatment (TRT, n = 26) groups. All mammary quarters in the udder of cows in the control group had 70-d (68 +/- 9 d) dry periods, whereas in each cow of the TRT group, 1 randomly selected half udder was dried at 70 d before ECD and the other half udder continued to be milked twice daily until dried at 30 d before ECD. From 80 through 70 d before ECD, amounts of milk produced by the left and right half udders of cows in the TRT group were measured at the first-shift milking. No differences were detected in the actual or relative amounts of milk produced by the left (3.46 +/- 0.2 kg; 48.8 +/- 1.0%) and the right (3.63 +/- 0.2 kg; 51.2 +/- 1.0%) half udders. Furthermore, the actual and relative amounts of milk produced by the half udders (n = 12 left, 14 right) subsequently dry for 67 +/- 7 d (3.56 +/- 0.2 kg; 50.2 +/- 1.0%) and the half udders (n = 14 left, 12 right) subsequently dry for 27 +/- 7 d (3.54 +/- 0.2 kg; 49.8 +/- 1.0%) did not differ before they were dried. However, from 3 to 100 d of the subsequent lactation, the 30-d dry half udders produced 18.9% less milk than the 70-d dry half udders (16.3 vs. 20.1 +/- 1.0 kg/d). In addition, relative amounts of total-udder milk produced by the 30- and 70-d dry half udders in the same cow differed (44.9 vs. 55.1 +/- 0.2%, respectively). Cows in the control group produced more milk than cows in the TRT group through 80 DIM (39.5 vs. 35.2 +/- 0.6 kg/d), but not from 3 through 150 DIM (39.0 vs. 36.2 +/- 1.6 kg/d). Thus, half udders that produced the same actual and relative amounts of milk before being dried did not do so when given a 30-d dry period instead of a 70-d dry period. When compared with the pre-dry value (49.8%), the relative contribution of half udders dry for 30 d to the total milk yield during the first 100 DIM was decreased by 9.8%.

Invited Review: Bovine Studies on Optimal Lengths of Dry Periods,

Milk production per cow has increased as a result of progressive changes in the genetics and management of the dairy animal population. A management constant during many decades of progress has been the widely adopted dry period length of 51 to 60 d. The scientific basis for that industry standard was examined to assess its validity as the appropriate standard for the modern dairy industry. If subsequent milk yields can be sustained fully after dry periods that are shorter than the current standard, then considerable milk is being forfeited by retaining longer dry periods. Conversely, failure to allow any dry period will result in a significant decrease in subsequent milk synthesis and secretion. Most studies to determine the minimum length of dry period required have involved retrospective analyses of observational data. Only five experiments have been reported in which dairy cows were assigned, at random, to planned 30- and 60-d dry periods. Estimates of the change in subsequent milk production when days dry were decreased from 50 to 57 d to 30 to 34 d ranged from a 10% decrease to a 1% increase. However, lower yields after shorter dry periods may be partially offset by greater milk yields in the previous lactation if such cows are milked 3 to 4 wk longer. Environmental factors that influence milk production as well as the biological processes that occur within the mammary gland during the nonlactating period must be considered when dry period lengths are compared. Importantly, additional animal trials that specifically assign cows randomly to the dry period lengths to be evaluated are needed to determine optimal dry period lengths for modern dairy cows in differing management scenarios.

Milk production and feed intake of Holstein cows given short (30-d) or normal (60-d) dry periods

Eighty-four Holstein cows were utilized to evaluate effects of dry period (60 d vs. 30 d), with or without estradiol cypionate (ECP) injections to accelerate mammary involution, on prepartum and postpartum dry matter intake (DMI), body weight (BW), body condition score (BCS), and subsequent milk yield (MY). Treatments were arranged in a 3 x 2 x 2 factorial design that included dry period (30 d dry, 30 d dry + ECP, and 60 d dry), prepartum and postpartum bovine somatotropin (bST; 10.2 mg/d), and prepartum anionic or cationic diets. To accelerate mammary involution, ECP (15 mg) was injected intramuscularly at dry-off. No interaction of bST or prepartum diet with dry period length was detected on BW, BCS, or MY. No significant effects of dry period length on prepartum DMI, BW, or BCS were detected. Cows with shorter dry periods maintained postpartum BCS better and tended to have greater DMI immediately postpartum. Mean daily yields of milk for dry period groups did not differ during overall lactation period (1 to 21 wk). Injection of ECP at the onset of the 30-d dry period did not affect MY. No significant differences due to dry period length were detected for milk, 3.5% FCM, or SCM yields during first 10 wk of lactation. Data indicated that a short dry period protocol can be used as a management tool with no loss in the subsequent milk production of dairy cows.

Milk production of dairy cows treated with estrogen at the onset of a short dry period

The objective was to determine whether the use of estradiol-17beta (E2) at the initiation of short dry periods prevented an anticipated decline in milk production in the subsequent lactation. Lactating Holstein cows (n = 66) were dried at either 60 or 30 d before expected calving. Treatments in a 2 x 2 factorial arrangement included: D60 (n = 19, 60-d dry, no E2), D60 + E2 (n = 18, 60-d dry, E2), D30 (n = 15, 30-d dry, no E2), and D30 + E2 (n = 14, 30-d dry, E2). To accelerate mammary involution, estradiol-17beta (15 mg in 4 ml of ethanol) was injected subcutaneously daily for 4 d beginning 30 d before expected calving. Parturitions occurred between November 1995, and March 1996. Actual days dry for respective treatments were 57.3, 60.6, 33.9, and 33.8 +/- 1.7 d. Onset of parturition, calving difficulty, and cow health were not affected by E2. Actual 305-d milk yields for the lactation completed immediately before the experimental dry period were 10,318, 10,635, 10,127, and 10,447 +/- 334 kg, respectively; and were 9942, 9887, 9669, and 10,172 +/- 387 kg, respectively, for the lactation immediately following treatment. Respective pre- and posttreatment mature equivalent 305-d yields were 9574, 9861, 9812, and 9724 +/- 297 kg; 8987, 8843, 9126, and 9008 +/- 294 kg. Milk yields did not differ across treatments. Cows with a 34-d dry period were as productive as cows with a 59-d dry period. Estradiol-17beta had no effect, but perhaps should be evaluated with dry periods shorter than 34 d.

Milk plasmin during bovine mammary involution that has been accelerated by estrogen

The purpose of this study was to evaluate whether the plasminogen and plasmin system within bovine mammary secretions was influenced by an estrogen treatment that was used to accelerate mammary tissue involution. Holstein cows were injected with 4 ml of ethanol excipient (n = 21) or 15 mg of estradiol-17 beta (n = 23) on each of the 4 d that preceded final milk removal. Dates of final milk removal (d 0) were designated as 60 d prior to expected dates of calving. Each mammary quarter was sampled once to collect secretions that corresponded to d 0, 3, 11, and 25 or d 1, 7, 18, and 30 of the dry period. Concentrations of plasminogen, plasmin, and somatic cells in secretions increased earlier for treated cows than for control cows. The ratio of plasminogen to plasmin in secretions decreased earlier for treated cows than for control cows. These responses support the suggestion that the plasminogen and plasmin system is involved in the involution of bovine mammary tissue. Estrogen treatment increased the activation of plasminogen, which was evidenced by a precipitous decrease in the ratio of plasminogen to plasmin that occurred as concentrations of plasminogen and plasmin increased. The activation of plasminogen likely contributed to the increased rate of mammary tissue involution that was effected by exogenous estrogen. Endogenous estrogen secreted by the developing fetal and placental unit might mediate, in part, the gradual involution that occurs during lactation.

Estrogen administered at final milk removal accelerates involution of bovine mammary gland

To evaluate whether estrogen hastened involution of mammary tissue, Holstein cows were injected with 4 ml of ethanol excipient (n = 21) or 15 mg of estradiol-17 beta (n = 23) on each of the 4 d that preceded final milk removal. Dates of final milk removal (d 0) were designated as 60 d prior to expected dates of calving. Milk volumes were recorded, and samples were collected prior to the first and fourth injections. During the dry period, each mammary quarter within the cow was sampled once to collect secretions on dates that corresponded to d 0, 3, 11, and 25 or 1, 7, 18, and 30 of the dry period. Milk synthesis and secretion declined abruptly because of treatment. The decreased concentrations of alpha-lactalbumin, lactose, citrate, and potassium in secretions of controls, as well as the increased somatic cells, protein, lactoferrin, and sodium, occurred earlier in secretions from treated cows. These shifts of approximately 6 d, relative to days dry, suggested that exogenous estradiol increased the involution rate of mammary tissue.

Milk yields and hormone concentrations of Holstein cows in response to sometribove (somatotropin) treatment during the dry period

Holstein cows (n = 135) under commercial management were used to determine whether sometribove (recombinant methionyl bST, 25 mg/d) administered during the dry period affected milk yield during the ensuing lactation. Cows scheduled to begin lactations (greater than or equal to 2) during January to March were assigned randomly to treatments of sodium bicarbonate excipient (n = 67) or bST (25 mg/d, n = 68). Subcutaneous injections were given for 14 d, corresponding to d -21 to -7 relative to expected calving date. Days dry prior to first injection (64.0, 60.2) and number of injections received (13.9, 13.8) were similar for control and treatment groups, but days from last injection to calving (8.8, 7.1) differed. No differences in incidence of dystocia or udder edema were detected. Previous lactation yields were 8251 and 7952 kg, and yields for lactations following treatment were 8328 and 7852 kg, based on complete lactation data. Mean test date 3.5% FCM yields for control and treated groups during experimental lactation differed before (30.3 vs. 28.1 kg) but not after (29.5 vs. 28.4 kg) covariance adjustment for previous total lactation milk yield. Test of heterogeneity of regression provided no evidence that respective curves for FCM yield during lactation were not parallel or of different magnitude. Elevation of serum bST during 2 wk of the dry period resulted in no apparent increase in extent of mammogenesis or lactogenesis that was translated into an increase in milk yield.

Responses of lactating dairy cows to protected fats or whole cottonseed in low or high forage diets

Thirteen treatments to compare effects of dietary fat on milk yield and composition were control, 15% whole cottonseed, and 2 and 4% Ca-tallowate factorially distributed in low forage (35% corn silage DM) with 14 or 18% CP and high forage (66% corn silage) diets with an additional diet of 8% Ca-tallowate. Different treatments were fed to 36 cows in each of three 28-d periods. Feeding 2 and 4% Ca-tallowate improved milk yield with high forage, although DM intake was slightly depressed; compared with 4% Ca-tallowate, DM intake and milk yield were depressed by 8% Ca-tallowate. Across all diets, whole cottonseed depressed DM intake and milk yield more than when nearly equal fat came from Ca-tallowate (4%). Calcium-tallowate depressed milk fat percentage linearly. Milk fat from cows fed whole cottonseed or Ca-tallowate contained unsaturated fatty acids (mostly C18:1) and lesser quantities of short-chain fatty acids. In a subsequent experiment, Ca-tallowate depressed milk fat percentage, whereas Megalac (calcium salts of fatty acids from palm oil) did not. In a field study, one trial with 210 cows in midlactation showed no effect on milk yield and composition from .54 kg of Megalac/d for 60 d, nor was there any effect detected with 121 cows in early lactation from feeding of .45 kg of Megalac/d for 90 d.

Effects of bovine somatotropin on milk yield and composition, dry matter intake, and some physiological functions of Holstein cows during heat stress

Thirteen Holstein cows (46 to 106 d postpartum) were assigned to a partially balanced incomplete block experiment to evaluate effects of bovine somatotropin (20.6 mg monomer/d) and environment (shade and no shade) on milk yield and composition, feed intake, rectal temperature, respiration rate, and concentrations of hormones in plasma. Two treatment periods were 29 d each, preceded by 10-d preliminary periods. Water and cotton-seed hull-based diet were available ad libitum. Mathematical model for statistical analyses included cow, period, treatment, environment, day, and estimable interactions. Black globe temperature and respiration rate and rectal temperature of cows were higher in no shade. Milk and 3.5% FCM yields and feed intake of cows in no shade were approximately 9.5 and 16% less than for cows in shade. Much of the effect of heat stress was associated with reduced DM intake. The 3.5% FCM, but not milk yield, was increased by injections of bovine somatotropin. Dry matter intake was unaffected, but milk, 3.5% FCM, and component yields were increased by bovine somatotropin when adjusted for DM intake. Response of cows to bovine somatotropin was not different in the two environments, except cows injected with bovine somatotropin had slightly higher body temperature and respiration rate. Increased production responses of heat-stressed cows due to bovine somatotropin were less than in cows injected under more temperate conditions.

Effect of pregnancy, milk yield, and somatic cell count on bovine milk fat hydrolysis

During 12 mo, 1818 milk samples were collected from Holsteins and Jerseys (n = 261) to evaluate effects of advancing lactation and pregnancy on milk fat hydrolysis. Aliquots, cooled immediately and stored 48 h at 4 degrees C, were analyzed for free fatty acid content. Holsteins had higher acid degree values than Jerseys (.90 vs. .62). No difference in values was detected between alternate a.m. (.74) and p.m. (.76) sampling times. Repeatability of acid degree values from lactation to lactation was low (.22). Days in milk, days pregnant, and milk yield had curvilinear effects on acid degree values, whereas SCC effects were linear. Estimated acid degree value at 335 d in milk (average dry-off) was lowered from .80 to .63 when adjusted for days pregnant and to .48 when adjusted also for milk yield. These responses agree with the increased acid degree values associated with two late lactation events: increasing day pregnant and decreasing milk yield. Estrogen secreted by the developing fetal-placental unit could mediate changes in milk composition that promote milk fat hydrolysis.

Interactions of climatic factors affecting milk yield and composition

Objectives were to evaluate effects of interactions of maximum temperature, minimum relative humidity, and solar radiation on milk yield and constituent traits. Effects of climate variables and their interactions were significant but small in most cases. Second order regression models were developed for several variables. Six were examined in detail: Holstein and Jersey milk yields, Holstein fat and Feulgen-DNA reflectance percent, and Jersey protein percent and yield. Maximum temperature had greatest influence on each response, followed by minimum relative humidity and solar radiation. Optimum conditions for milk production were at maximum temperatures below 19.4 degrees C, increasing solar radiation, and minimum relative humidity between 33.4 and 78.2% (cool sunny days, moderate humidity). Maximum Holstein fat percent of 3.5% was predicted for maximum temperatures below 30.8 degrees C, minimum relative humidity below 89%, and solar radiation below 109 Langleys; actual mean Holstein fat percent was 3.35%. Optimum climatic conditions for Jersey protein percent were at maximum temperature of 10.6 degrees C with solar radiation at 300 Langleys and relative humidity at 16% (cool sunny days, low humidity). Because noteworthy interactions existed between climate effects, response surface methodology was suitable for determining optimum climatic conditions for milk production.

Induction of lactation: histological and biochemical development of mammary tissue and milk yields of cows injected with estradiol-17 beta and progesterone for 21 days

Lactations were induced in nonpregnant, nonlactating dairy cows by subcutaneous injections of estradiol-17 beta and progesterone for 21 d (.10 and .25 mg/kg body weight/d) and dexamethasone (.028 mg/kg body weight/d) on d 31 to 34. Milking was initiated on d 35. Each cow was biopsied two or three times during the experiment with five to eight mammary tissue biopsies on d 0, 7, 14, 21, 28, 35, 49, and 130. Mammary tissue preinjection had abundant connective and adipose tissues with limited lobuloalveolar structures. Beginning on d 7, there was decreased stroma, increased epithelial cell area, increased lobuloalveolar architecture, plus the accumulation of intracellular and intraluminal secretions which were high in lipid droplets. From d 7 through 35, these changes were progressive although variable among cows. Changes in activities of enzymes and concentrations of ribonucleic acid and deoxyribonucleic acid were gradual during this time but essentially paralleled histological development. Tissue samples during lactation (d 49 and 130) showed increased histological and biochemical development; development was maximal for d 130 samples. Fourteen of 15 cows that lactated had mean daily yields of milk more than 5 kg and yields of milk of 12 cows with projected or actual 305-d lactations were 63.0% of that during their previous natural lactations. Reasons for less yields of milk and for varied patterns of tissue development were not identified nor explained by concentrations of several selected hormones in plasma.

Yield and composition of milk and weight gain of nursing pigs from sows fed diets containing fructose or dextrose

Yield and composition of milk and growth of nursing pigs in response to dietary treatment were estimated from 25 lactating sows during a 22-d period. Eight sows were fed 6 kg/d of a corn-soybean control diet (C sows). Nine were fed the control diet in which approximately 6.5 g X kg body weight (BW-1) X d-1 of carbohydrate was supplied by fructose corn syrup (F sows) and eight were fed the control diet containing equivalent carbohydrate supplied by powdered dextrose (D sows). Blood samples collected via jugular cannulae were analyzed for plasma concentrations of fructose, glucose and insulin. Concentrations of fructose and glucose from F sows were significantly higher throughout the study than that from D and C sows, while insulin concentration was approximately 2.5-fold lower. Milk yield from F sows on d 14 and 21 was significantly higher and pigs weaned on d 21 were heavier than those from D and C sows. Sows fed the diet containing fructose experienced significant BW loss during lactation. Coefficients of gross correlation across treatments showed milk yield and litter weight gain to be negatively associated with percentages of protein, lipids and total solids in milk, but positively associated with concentrations of lactose and gross energy. Nursing pig weight gain at weaning was more responsive to total yields of milk and milk nutrients than to composition. These data support the hypothesis that source of metabolizable energy (ME) affects milk yield, composition and efficiency at which the sow converts dietary nutrients into milk.

Climatological and genetic effects on milk composition and yield

Results confirm most other research on milk composition and yield. All responses were affected by climate, some considerably more than others, if percent of error variance is the criterion. Jersey yields were less sensitive to climate than were Holstein, but Jersey milk composition appeared more sensitive. Somatic cell count (REF), a measure of mastitis, was affected by climate but less than all other variables except protein/fat and LM%. Needed are estimates of interactions between climatic effects and response surface models to quantify possible improvement in performance following environmental modification. Genetic correlations between milk yield and REF and chloride % suggest that single trait selection for milk yield might increase incidence of mastitis although phenotypic correlations indicate that high yields and absence of mastitis are correlated.

Effect of exogenous estradiol and progesterone upon lipase activity and spontaneous lipolysis in bovine milk

Three of six lactating Jersey cows received estradiol--17 beta and progesterone (.10 and .25 mg/kg body weight per day subcutaneously for 7 consecutive days. Lipase activity and acid degree were determined for morning milk samples stored 24 h at 4 degrees C. Whole milk lipase activity did not increase over control milk samples; however, lipase activity of cream fraction and percent whole milk lipase activity in cream fraction increased 200 and 100%. Increases in acid degree occurred also and were closely correlated (.8 to .9) with lipase activity of cream fraction and percent whole milk lipase activity in cream fraction. Cooling was not required to effect association of lipase with cream fraction. Two treated cows developed mastitis-like symptoms after elevation in lipase activity of cream fraction and acid degree. Estradiol alone evoked similar responses.

Rumen and fecal tungstic acid precipitable nitrogen and total amino nitrogen in cows fed complete diets

Tungstic acid precipitable N and nonprecipitable N were measured in feed, rumen and feces of cows fed complete diets, and changes in ratios of these components to chromic oxide were used to estimate net changes in true protein from feed to rumen to feces. Apparent digestible true protein leaving the rumen was assumed to be metabolizable protein. Rumen contents were hand mixed before sampling from rumen-fistulated cows so that samples would be as representative of total rumen contents as possible, and these samples were assumed to represent contents being passed to small intestine. Metabolizable protein percentages of three low protein basal diets containing 1.90, .95 and 0% urea and three similar diets with added soybean meal fit responses of milk yield obtained in a previous experiment much better than metabolizable protein estimated from literature values for various feedstuffs. Net true protein digestion estimates confirmed negative performance from 1.90% urea basal diets compared with performance from other basal diets. An experiment in which rumen samples were taken by stomach tube from intact cows showed rumen samples were not representative of total rumen contents, at least not for chromic oxide percentage, and, consequently, net true protein digestion could not be estimated a well as with fistulated cows.

Sensitive colorimetric determination of cholesterol in dairy products

Cholesterol can be determined colorimetrically in dairy products at levels of larger than or equal to 10 mug (coefficient of variation = 5.3%) with an o-phthalaldehyde reagent when non-cholesterol lipids are eliminated prior to color development. Absorbance for 2 mg tripalmitin was found to be equivalent to about 20 mug cholesterol. Saponification followed by hexane extraction removed interfering lipids. Using the described procedure, 238 individual raw milk samples were found to contain 144.4+/-37.9 mug cholesterol/ml, while their skim milk portions had 26.5+/-6.4 mug cholesterol/ml (mean +/- standard deviation). The o-phthalaldehyde cholesterol estimates agreed with those obtained by a gas-liquid chromatographic procedure when cheese and ice cream were analyzed by the colorimetric procedure with and without prior fat extraction.

Factors that influence milk cholesterol and lipid phosphorus: content and distribution

Average cholesterol content of 356 raw milk samples was 152.2 mug/ml and upon centrifugation (3000 X g for 8 min), 16.9% was distributed in the skim milk phase. Lipid phosphorus averaged 19.0 mug/ml and was partitioned 50:50 between cream and skim milk phases. Weight ratios of cholesterol to lipid phosphorus for milk and skim milk were 8.30:1 and 2.94:1. When variation due to milk yield, fat percent, and somatic cell numbers (deoxyribonucleic acid percent reflectance) was accounted for by least squares, cholesterol content and distribution did not differ among breeds (Holstein, Jersey, and Guernsey). Breed differences in lipid phosphorus content of whole milk could not be detected. However, Holsteins had a significantly lower content of lipid phosphorus and a higher weight ratio for skim milk. Milk yield, fat content, and somatic cells affected responses of cholesterol and lipid phosphorus. This supports a multiple origin concept for membrane material in skim milk.

Effect of a synthetic corticoid on milk yield and composition and on blood metabolites and hormones in dairy cows

Twenty-five dairy cows were assigned randomly by breed to flumethasone treatment (10 mug/day, 13 cows) or placebo control (12 cows) from 4 to 44 wk of lactation. Lactation means and trends with stage of lactation were treatment responses. Mean milk yields of cows supplemented with flumethasone were not significantly different from controls. Mean metabolite (glucose, nonesterified fatty acids, and total esterified fatty acids) and hormone concentrations (corticoids, insulin, and prolactin) of blood plasma and their trends throughout lactation were unaffected by supplementation. Data were pooled to determine effects of stage of lactation, temperature, pregnancy, and month on these variables. Changes during lactation were systematic for feed intake, body weight, milk yield, milk components except somatic cells, blood metabolites, and prolactin. At environmental temperatures above 18 C, effects were consistently negative for milk yield and composition, but only above 26 C for feed intake. Prolactin of plasma increased with increasing temperature to 18.2 C and then decreased. No other plasma metabolite or hormone was affected by days pregnant, age, or temperature. Months affected feed intake, milk yield, milk fat percentages, all blood metabolites, and prolactin. Prolactin concentrations increased as daylight hours increased. Our inability to augment established lactation by feeding a supplement of synthetic glucocorticoid to lactating cows is consistent with the view that a lack of avialable corticoids does not limit persistency of lactation in the cow.