Healthy environments for athleTes (HEAT): environmental conditions along a 90 km ultra-marathon event, South Africa.

This paper provides an overview of the HEAT (Healthy Environments for AthleTes) project, which aims to understand the impact of environmental conditions on athlete health and performance during major sporting events such as long-distance running, cycling, and triathlons. In collaboration with the SAFER (Strategies to reduce Adverse medical events For the ExerciseR) initiative, the HEAT project carried out a field campaign at the 2022 Comrades Marathon in the KwaZulu-Natal province of South Africa. The measurement campaign deployed seven weather stations, seven PM2.5 monitors and one spore trap along the 90 km route to capture spatially representative measurements of complex micro-climates, allergenic aerospora, and particulate matter exposure. The results indicate that runners were exposed to moderate risk heat stress conditions. Novel findings from this initial campaign shows elevated and potentially harmful PM2.5 levels at spectator areas, possibly coinciding with small fire events around the race day festivities. Our findings show values PM2.5 levels over the WHO 24-h guidelines at all stations, while 2000 µg/m3 at two stations. However, the lack of an acute exposure standard means direct health impacts cannot be quantified in the context of a sport event. The HEAT project highlights important aspects of race day monitoring; regional scale climatology has an impact on the race day conditions, the microclimatic conditions (pollution and meteorology) are not necessarily captured by proximity instruments and direct environmental measurements are required to accurately capture conditions along the route.

CARE: Protocol of a randomised trial evaluating the feasibility of preoperative intentional weight loss to support postoperative recovery in patients with excess weight and colorectal cancer.

AIM: Excess weight increases the risk of morbidity following colorectal cancer surgery. Weight loss may improve morbidity, but it is uncertain whether patients can follow an intensive weight loss intervention while waiting for surgery and there are concerns about muscle mass loss. The aim of this trial is to assess the feasibility of intentional weight loss in this setting and determine progression to a definitive trial. METHODS: CARE is a prospectively registered, multicentre, feasibility, parallel, randomised controlled trial with embedded evaluation and optimisation of the recruitment process. Participants with excess weight awaiting curative colorectal resection for cancer are randomised 1:1 to care as usual or a low-energy nutritionally-replete total diet replacement programme with weekly remote behavioural support by a dietitian. Progression criteria will be based on the recruitment, engagement, adherence, and retention rates. Data will be collected on the 30-day postoperative morbidity, the typical primary outcome of prehabilitation trials. Secondary outcomes will include, among others, length of hospital stay, health-related quality of life, and body composition. Qualitative interviews will be used to understand patients' experiences of and attitudes towards trial participation and intervention engagement and adherence. CONCLUSION: CARE will evaluate the feasibility of intensive intentional weight loss as prehabilitation before colorectal cancer surgery. The results will determine the planning of a definitive trial.

Assessment of gastrointestinal health in racing Alaskan sled dogs using capsule endoscopy and inflammatory cytokines.

OBJECTIVES: Exercise-induced gastrointestinal syndrome occurs in dogs and people and might compromise athlete performance by increasing intestinal permeability and causing gastrointestinal erosions. Racing sled dogs often receive acid suppressant prophylaxis which decreases the incidence of gastric erosions induced by exercise. The objectives were to quantify intestinal injury by measuring serum pro-inflammatory cytokine concentrations before and after exercise and to evaluate gastrointestinal mucosa using video capsule endoscopy after exercise. MATERIALS AND METHODS: Prospective study of 12 racing Alaskan sled dogs receiving approximately 1 mg/kg omeprazole once daily from the day before the race until race completion. Blood was drawn before and 8 to 10 hours after an endurance race for the quantification of cytokines. Gastrointestinal tract mucosa was assessed with video capsule endoscopy immediately post-race. RESULTS: Eight of nine dogs (89%; 95% confidence interval 52 to 100%) had gastric erosions; all dogs (100%, 95% confidence interval 63 to 100%) had small intestinal erosions. Most of the dogs (seven of nine) had straw or foreign material present. Cytokine levels were not different from before to after the race. CLINICAL SIGNIFICANCE: Video capsule endoscopy identified gastrointestinal tract mucosal erosions after exercise in all dogs receiving once-daily omeprazole treatment, though other causes for the lesions besides exercise are possible.

Tenecteplase Versus Alteplase for Acute Stroke: Mortality and Bleeding Complications.

STUDY OBJECTIVE: Intravenous thrombolysis with alteplase has been the foundation of initial treatment of acute ischemic stroke for several decades. Tenecteplase is a thrombolytic agent that offers logistical advantages in cost and administration relative to alteplase. There is evidence that tenecteplase has at least similar efficacy and safety outcomes compared with alteplase for stroke. In this study, we compared tenecteplase versus alteplase for acute stroke in a large retrospective US database (TriNetX) regarding the following 3 outcomes: (1) mortality, (2) intracranial hemorrhage, and (3) the need for acute blood transfusions. METHODS: In this retrospective study using the US cohort of 54 academic medical centers/health care organizations in the TriNetX database, we identified 3,432 patients treated with tenecteplase and 55,894 patients treated with alteplase for stroke after January 1, 2012. Propensity score matching was performed on basic demographic information and 7 previous clinical diagnostic groups, resulting in a total of 6,864 patients with acute stroke evenly matched between groups. Mortality rates, the frequency of intracranial hemorrhage, and blood transfusions (as a marker of significant blood loss) were recorded for each group over the ensuing 7- and 30-day periods. Secondary subgroup analyses were conducted on a cohort treated from 2021 to 2022 in an attempt to determine whether temporal differences in acute ischemic stroke treatment would alter the results. RESULTS: Patients treated with tenecteplase had a significantly lower mortality rate (8.2% versus 9.8%; risk ratio [RR], 0.832) and lower risk of major bleeding as measured by the frequency of blood transfusions (0.3% versus 1.4%; RR, 0.207) than alteplase at 30 days after thrombolysis for stroke. In the larger 10-year data set of patients with stroke treated after January 1, 2012, patients receiving tenecteplase were not found to have a statistically different incidence of intracranial hemorrhage (3.5% versus 3.0%; RR, 1.185) at 30 days after the administration of the thrombolytic agents in patients. However, a subgroup analysis of 2,216 evenly matched patients with stroke treated from 2021 to 2022 demonstrated notably better survival and statistically lower rates of intracranial hemorrhage than the alteplase group. CONCLUSION: In our large retrospective multicenter study using real-world evidence from large health care organizations, tenecteplase for the treatment of acute stroke demonstrated a lower mortality rate, decreased intracranial hemorrhage, and less significant blood loss. The favorable mortality and safety profiles observed in this large study, taken together with previous randomized controlled trial data and operational advantages in rapid dosing and cost-effectiveness, all support the preferential use of tenecteplase in patients with ischemic stroke.

Cost-effective restoration for carbon sequestration across Brazil's biomes.

Tropical ecosystems are central to the global focus on halting and reversing habitat destruction as a means of mitigating carbon emissions. Brazil has been highlighted as a vital part of global climate agreements because, whilst ongoing land-use change causes it to be the world's fifth biggest greenhouse gas emitting country, it also has one of the greatest potentials to implement ecosystem restoration. Global carbon markets provide the opportunity of a financially viable way to implement restoration projects at scale. However, except for rainforests, the restoration potential of many major tropical biomes is not widely recognised, with the result that carbon sequestration potential may be squandered. We synthesize data on land availability, land degradation status, restoration costs, area of native vegetation remaining, carbon storage potential and carbon market prices for 5475 municipalities across Brazil's major biomes, including the savannas and tropical dry forests. Using a modelling analysis, we determine how fast restoration could be implemented across these biomes within existing carbon markets. We argue that even with a sole focus on carbon, we must restore other tropical biomes, as well as rainforests, to effectively increase benefits. The inclusion of dry forests and savannas doubles the area which could be restored in a financially viable manner, increasing the potential CO2e sequestered >40 % above that offered by rainforests alone. Importantly, we show that in the short-term avoiding emissions through conservation will be necessary for Brazil to achieve it's 2030 climate goal, because it can sequester 1.5 to 4.3 Pg of CO2e by 2030, relative to 0.127 Pg CO2e from restoration. However, in the longer term, restoration across all biomes in Brazil could draw down between 3.9 and 9.8 Pg of CO2e from the atmosphere by 2050 and 2080.

Creating a Chest Wall Injury and Reconstructive program: A single center experience with rib fractures.

BACKGROUND: New Chest Wall Injury and Reconstructive Centers (CWIRC) are emerging; this study aims to investigate the potential benefits of implementing a CWIRC at a single institution. We hypothesized that patients treated at CWIRC will have improved outcomes. METHODS: We instituted a CWIRC in 2019 at our American College of Surgeons (ACS) Level One Trauma Center. We retrospectively compared trauma patients with rib fractures who presented to our center 18 months before (PRE-C) and 18 months after CWIRC implementation (POST-C). Outcomes measured included mortality, length of stay (LOS), intensive care unit (ICU-LOS), readmission rates, and unplanned ICU admission. RESULTS: There were 192 PRE-C patients, compared to 388 POST-C. The mortality in PRE-C was not significantly different compared to the POST-C group (11.46% vs 8.8%, p=0.308). There were also no differences in LOS, ICU-LOS, readmission, and unplanned ICU admission. ICU utilization was dramatically different: PRE-C 17.8% were admitted to ICU compared to 35.6% POST-C (p<0.0001). CONCLUSIONS: The number of patients admitted with rib fractures to our center nearly doubled after CWIRC establishment. Early diagnosis and triage led to significantly more admissions to higher levels of care. There are trends toward improved outcomes using practice management protocols, albeit with higher ICU utilization. Establishment of a CWIRC should be considered for level 1 ACS trauma centers and as utilization of established CWIRC protocols are increased, patients will have improved outcomes. LEVEL OF EVIDENCE: IV STUDY TYPE: Retrospective chart review.

Key predictors and burden of meticillin-resistant Staphylococcus aureus infection in comparison with meticillin-susceptible S. aureus infection in an Australian hospital setting.

BACKGROUND: Staphylococcus aureus is associated with significant mortality and increased burden on the healthcare system. Relatively few reliable estimates are available regarding the impact of meticillin-resistant S. aureus (MRSA) infection compared with meticillin-susceptible S. aureus (MSSA) infection. AIMS: To compare patients with MRSA infection and MSSA infection to identify differences in inpatient mortality, length of stay and costs of hospital services, and identify predictors of MRSA as a cause of S. aureus infection. METHODS: An analytical, retrospective, longitudinal study using non-identifiable linked data on adults admitted to hospitals of a health district in Australia with a diagnosis of S. aureus infection over a 10-year period. The main outcome measure was 30-day inpatient mortality. Secondary endpoints included total overnight stays, all-cause inpatient mortality, and hospitalization costs within 1 year of index admission. FINDINGS: Inpatient mortality at 30, 100 and 365 days was estimated to be significantly greater for patients with MRSA infection. The mean additional cost of MRSA infection when controlling for additional factors was $5988 and 4 nights of additional hospital stay per patient within 1 year of index admission. Key predictors of MRSA infection were: date of index admission; higher comorbidity score; greater socio-economic disadvantage; admission to hospital other than via the emergency department; older age; and prior admission to hospital within 28 days of index admission. CONCLUSIONS: MRSA infection is associated with increased inpatient mortality, costs and hospital length of stay compared with MSSA infection. Efforts are required to alleviate the additional burden of MRSA infection on patients and healthcare systems.

Effects of milk replacer allowances and levels of starch in pelleted starter on nutrient digestibility, whole gastrointestinal tract fermentation, and pH around weaning.

The objectives of this study were to examine the effects of pelleted starter diets differing in starch and neutral detergent fiber (NDF) content when fed differing levels of milk replacer (MR) on nutrient digestibility, whole gastrointestinal tract fermentation, pH, and inflammatory markers in dairy calves around weaning. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) in a 2 × 2 factorial design based on daily MR allowance and amount of starch in pelleted starter (SPS): 0.691 kg of MR per day [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch on DM basis, respectively), and 1.382 kg of MR per day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Starting on d 35, an indwelling pH logger was inserted orally to monitor rumen pH until calves were dissected at the end of the study in wk 8. Higher SPS calves showed an increase in rumen pH magnitude (1.46 ± 0.07) compared with low SPS calves (1.16 ± 0.07), a decrease in rumen pH in wk 8 (high SPS: 5.37 ± 0.12; low SPS: 5.57 ± 0.12), and a decrease in haptoglobin in wk 8 (high SPS: 0.24 ± 0.06 g/L; low SPS: 0.49 ± 0.06 g/L). The majority of differences came from increased starter intake in general, which suggests that with completely pelleted starters the differences in starch and NDF do not elicit drastic changes in fermentation, subsequent end products, and any resulting inflammation in calves around weaning.

CO2 fluxes from three different temperate grazed pastures using Eddy covariance measurements.

Grasslands cover around 25% of the global ice-free land surface, they are used predominantly for forage and livestock production and are considered to contribute significantly to soil carbon (C) sequestration. Recent investigations into using 'nature-based solutions' to limit warming to <2 °C suggest up to 25% of GHG mitigation might be achieved through changes to grassland management. In this study we evaluate pasture management interventions at the Rothamsted Research North Wyke Farm Platform, under commercial farming conditions, over two years and consider their impacts on net CO2 exchange. We investigate if our permanent pasture system (PP) is, in the short-term, a net sink for CO2 and whether reseeding this with deep-rooting, high-sugar grass (HS) or a mix of high-sugar grass and clover (HSC) might increase the net removal of atmospheric CO2. In general CO2 fluxes were less variable in 2018 than in 2017 while overall we found that net CO2 fluxes for the PP treatment changed from a sink in 2017 (-5.40 t CO2 ha-1 y-1) to a source in 2018 (6.17 t CO2 ha-1 y-1), resulting in an overall small source of 0.76 t CO2 ha-1 over the two years for this treatment. HS showed a similar trend, changing from a net sink in 2017 (-4.82 t CO2 ha-1 y-1) to a net source in 2018 (3.91 t CO2 ha-1 y-1) whilst the HSC field was a net source in both years (3.92 and 4.10 t CO2 ha-1 y-1, respectively). These results suggested that pasture type has an influence in the atmospheric CO2 balance and our regression modelling supported this conclusion, with pasture type and time of the year (and their interaction) being significant factors in predicting fluxes.

Performance and visceral tissue growth and development of Holstein calves fed differing milk replacer allowances and starch concentrations in pelleted starter.

The objectives of this study were to investigate how milk replacer (MR) allowance and differing concentrations of starch and neutral detergent fiber in starter alters visceral tissue and overall growth of the calf. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) arranged in a 2 × 2 factorial based on daily MR allowance (MRA) and amount of starch in pelleted starter (SPS) as follows: 0.691 kg of MR/d [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch, respectively) and 1.382 kg of MR/day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered to minimize intake. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning, and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Intakes were measured daily, and body weight (BW) and blood samples were recorded and collected weekly. Calves were dissected in wk 8 for visceral tissue measurements. Overall, there was increased MR DM intake for the high- (0.90 ± 0.01 kg/d; ± SE) compared with the low-MRA (0.54 ± 0.01 kg/d) calves, whereas starter DM intake increased in low- (0.47 ± 0.05 kg/d) compared with high-MRA (0.20 ± 0.05 kg/d) calves, which was driven by increases in wk 6, 7, and 8. High-MRA calves had increased BW during wk 2, 3, 4, 5, 6, and 7. The difference in BW disappeared by wk 8, with overall average daily gain having a tendency to be increased in high (0.57 ± 0.04 kg/d) compared with low-MRA (0.50 ± 0.04 kg/d) calves, whereas average daily gain was increased in high-MRA calves during wk 2 and 3 and increased in low-MRA calves during wk 7 and 8. There were several differences throughout visceral tissue measurements, but most notably, an increase in rumen mass (i.e., full, empty, and digesta weights) in low- compared with high-MRA calves, as well as in low- compared with high-SPS calves was observed. The length, width, and 2-dimensional area of rumen papillae were also increased in low- (area: 0.88 ± 0.03 mm2) compared with high-MRA (0.46 ± 0.03 mm2) calves. The majority of differences were attributed to increased MR allowance, which contributed to reduced pelleted starter intake by more than 50% and reduced rumen development, whereas differences in starch intake from the completely pelleted starter had minimal effects on overall growth and tissue measurements.

Calcaneal offset index to measure hindfoot alignment in pes planus.

INTRODUCTION: Pes planus is a common three-dimensional (3D) deformity characterised by forefoot abduction, the collapse of the medial longitudinal arch, and hindfoot valgus. Several radiological measurements such as anteroposterior talocalcaneal angle (Kite's) and 'Calcaneal pitch angle' (CPA) exist to calculate the degree of hindfoot alignment in these patients with variable intra- and interobserver reliability. OBJECTIVE: To describe a new radiological ancillary method of measuring hindfoot alignment, the calcaneal offset index (COI). MATERIAL AND METHODS: Anteroposterior (mortise) and lateral view weight-bearing (WB) ankle radiographs of 200 consecutive patients referred for foot and ankle pain were reviewed. Demographic details, clinical indication, and COI calculation were undertaken on the mortise view along with the measurement of CPA for each patient. A one-way analysis of variance (ANOVA) was performed. Intraclass correlation coefficient (ICC) analysis was evaluated to assess the intraclass reliability between observers. RESULTS: There was a female preponderance of 2:1 in the study population with a mean age of 51.21 years (13-86 years). The calcaneal offset was increased in pes planus (hindfoot valgus). The p-value was 0.00023 on ANOVA. The COI gave an excellent interobserver correlation with ICC of 0.9 and moderate intraobserver reliability on the ICC analysis of 0.55. CONCLUSION: The COI can be an additional index of measuring hindfoot alignment in patients with pes planus. Contrary to the traditional angular measurements, this linear transverse plane measure is easier to calculate and reproducible. COI measurement has shown moderate intraobserver reliability but excellent interobserver reliability.

Hard to Kill: Inactivation of Plasmodiophora brassicae Resting Spores Using Chemical Disinfectants.

Biosafety practices, such as bioexclusion via sanitization, can prevent the spread of infectious soilborne threats such as the clubroot pathogen Plasmodiophora brassicae. Twenty-three chemical disinfectants were evaluated for efficacy against P. brassicae resting spores. Evans blue staining was used to directly measure the viability of P. brassicae resting spores after 20-min exposures to 10 concentrations of each of the 23 chemical disinfectants. Only nine disinfectants were capable of >95% inactivation, and only five were capable of inactivating >99% of resting spores. Bleach (sodium hypochlorite) and Spray Nine were the most effective disinfectants for inactivation of clubroot resting spores. AES 2500, SaniDate, and ethanol also inactivated >99% of resting spores but only at very high concentrations. A time course experiment showed that 10- to 12-min contact time was sufficient for ≥95% resting spore inactivation with Spray Nine and sodium hypochlorite, but ≥30-min contact was required for other disinfectants evaluated. These results will assist in guiding management recommendations for sanitization aimed at bioexclusion and biocontainment of P. brassicae.

Effects of mixed tocopherols added to milk replacer and calf starter on intake, growth, and indices of stress.

Vitamin E comprises 8 fat-soluble isoforms: α-, ß-, γ-, and δ-tocopherol and α-, ß-, γ-, and δ-tocotrienol. Yet the body preferentially uses α-tocopherol, and only α-tocopherol supplementation can reverse vitamin E deficiency symptoms. However, other isoforms influence many biological functions in the body, including inflammation and stress. Therefore, the study objective was to determine metabolic and performance responses in young calves fed diets containing a constant amount of α-tocopherol and increasing amounts of soybean oil-derived mixed γ- and δ-tocopherols. Holstein calves [n = 48; 2-3 d of age; 40.2 kg of initial body weight (BW), standard error = 0.54] were assigned to receive approximately 0, 5, 10, or 15 mg/kg of BW daily (treatments T0, T1, T2, and T3, respectively) of mixed tocopherols (TMIX) provided in milk replacer (MR) and calf starter. The TMIX liquid contained 86% γδ-tocopherols and 9% α-tocopherol. Milk replacers were formulated to contain approximately 0, 400, 800, or 1,200 mg of TMIX/kg for treatments T0, T1, T2, and T3, respectively. Calf starters were formulated to contain approximately 0, 250, 500, or 750 mg of TMIX/kg for treatments T0, T1, T2, and T3, respectively. Mean consumption of γδ-tocopherols was 0.0, 6.5, 14.3, and 20.5 mg/kg of BW, respectively. Milk replacer contained 24% crude protein (CP) and 20% fat on a dry matter (DM) basis. Calf starters were pelleted and offered for ad libitum consumption from 0 to 56 d. Starters contained 18 to 20% CP and 9 to 12% starch in the DM. On d 28, 4 calves per treatment were randomly selected for slaughter, and necropsy was performed. Samples of liver, duodenum, ileum, and trapezius muscle were collected and stored before analysis for α-, ß-, γ-, and δ-tocopherols and δ-tocotrienol. Data were analyzed using a completely randomized design using mixed model ANOVA with orthogonal polynomials to determine linear and quadratic effects of TMIX. Repeated-measures analyses were performed for data collected over time. Increasing dietary TMIX increased or tended to increase change in hip width at 28 and 56 d, respectively, and improved average daily BW gain and gain-to-feed ratio at 56 d. Increasing TMIX reduced plasma xanthine oxidase at 0 h and tended to reduce concentrations at 24 h following vaccination with 2 commercial vaccines on d 28; however, we detected no effect of TMIX following vaccination on d 56. Concentration of α-tocopherol in skeletal muscle declined quadratically with increasing TMIX, whereas ileal and liver γ-tocopherol increased linearly with increasing TMIX. The number of mucin-2 cells in the ileum increased more than 2-fold in calves fed T3. Addition of mixed tocopherols to diets of young dairy calves improved animal growth and altered indices of antioxidant metabolism.

Mortality and AIDS-defining events among young people following transition from paediatric to adult HIV care in the UK.

OBJECTIVES: To investigate risk of AIDS and mortality after transition from paediatric to adult care in a UK cohort of young people with perinatally acquired HIV. METHODS: Records of people aged ≥ 13 years on 31 December 2015 in the UK paediatric HIV cohort (Collaborative HIV Paediatric Study) were linked to those of adults in the UK Collaborative HIV Cohort (CHIC) cohort. We calculated time from transition to a new AIDS event/death, with follow-up censored at the last visit or 31 December 2015, whichever was the earliest. Cumulative incidence of and risk factors for AIDS/mortality were assessed using Kaplan-Meier and Cox regression. RESULTS: At the final paediatric visit, the 474 participants [51% female, 80% black, 60% born outside the UK, median (interquartile range) age at antiretroviral therapy (ART) initiation = 9 (5-13) years] had a median age of 18 (17-19) years and CD4 count of 471 (280-663) cell/µL; 89% were prescribed ART and 60% overall had a viral load ≤ 400 copies/mL. Over median follow-up in adult care of 3 (2-6) years, 35 (8%) experienced a new AIDS event (n = 25) or death (n = 14) (incidence = 1.8/100 person-years). In multivariable analyses, lower CD4 count at the last paediatric visit [adjusted hazard ratio = 0.8 (95% confidence interval: 0.7-1.0)/100 cells/µL increment] and AIDS diagnosis in paediatric care [2.7 (1.4-5.5)] were associated with a new AIDS event/mortality in adult care. CONCLUSIONS: Young people with perinatally acquired HIV transitioning to adult care with markers of disease progression in paediatric care experienced poorer outcomes in adult care. Increased investment in multidisciplinary specialized services is required to support this population at high risk of morbidity and mortality.

Effects of feeding milk replacer at a moderate rate, ad libitum, or with a step-up program on Holstein calf growth performance to 4 months of age.

The objective of this study was to evaluate 3 milk replacer (MR) feeding programs on calf performance to 4 mo of age. Male Holstein calves (n = 48; 2-3 d old) were randomly assigned to either a moderate rate of MR (MOD; 0.66 kg/d for 39 d, then 0.33 kg/d for 3 d), an ad libitum rate of MR (ADLIB; offered twice daily between 0630 and 0830 h and between 1430 and 1630 h for 35 d, 0.66 kg/d for 4 d, and 0.33 kg/d for 3 d), or a step-up rate of MR (STEPUP; increased from 0.32 to 0.62 kg/d in first 12 d, 0.66 kg/d for 27 d, and 0.33 kg/d for 3 d). The MR (25% CP, 18% fat) was fed twice daily to d 39 and once daily thereafter. During the nursery phase (0-56 d), calves were housed in individual pens and offered textured starter (40% starch, 21% CP on a DM basis) and water ad libitum. Calf body weight (BW) was measured initially and weekly thereafter. Hip widths (HW) were measured initially and every 2 wk thereafter. In the grower phase, (57-112 d), calves were grouped by previous treatment and moved to group pens (4 calves/pen). The same starter used in the nursery phase was blended with 5% chopped grass hay and offered ad libitum. Calf BW and HW were measured on d 56, 84, and 112. Total MR intake per calf averaged 27, 51, and 25 kg for MOD, ADLIB, and STEPUP programs, respectively, with a range of 42 to 63 kg for ADLIB. In the nursery phase, starter intake and feed efficiency were less for ADLIB versus MOD, whereas fecal scores and abnormal fecal score days were greater for calves fed ADLIB versus MOD. Calves fed STEPUP had lesser average daily gain than calves fed MOD. During the grower phase, initial BW was greater for ADLIB versus MOD, though final BW was not different between MOD and ADLIB or STEPUP. Calves previously fed MOD had greater average daily gain, feed efficiency, and HW change than calves fed ADLIB. In this study, feed efficiency was lower when MR was fed ad libitum, and growth advantages observed at 2 mo were lost by 4 mo of age.

Effects of milk replacer feeding rate and fat content on Jersey calf nutrient digestion and performance to 4 months of age.

This study evaluated effects of milk replacer (MR) feeding rate and fat concentration in MR on total-tract digestion (TTD) and growth performance in Jersey calves. Jersey heifer calves (n = 100, 2 blocks of 50; initially 30 ± 3.0 kg of body weight; 4-11 d of age) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of MR feeding rate [454 g for 42 d, and 227 g for 7 d (MOD); or 454 g for 7 d, 681 g for 35 d, and 341 g for 7 d (HI), as-fed basis] and MR fat content (17 or 24% fat as-fed basis). Milk replacers (24% crude protein as-fed basis) were reconstituted to 14% solids and fed in 2 equal feedings for 42 d, and then mornings only for 7 d. Textured calf starter (21% crude protein, 40% starch, dry matter basis) and water were offered for ad libitum consumption. From d 57 to 112, calf starter was mixed with 5% chopped grass hay. Calves were housed individually to d 56 and housed in groups (4-5 calves/pen) from d 57 to 112. Estimates of TTD were measured in 5 calves/treatment (block 1) at wk 3 of the study using acid-insoluble ash as an indigestible marker. From 0 to 56 d, calf starter intake (CSI) was greater for MOD vs. HI and 17 versus 24% fat; average daily gain was greater for HI versus MOD; and hip width change was greater for 17 versus 24% fat. Estimates of organic matter TTD were greater for HI versus MOD, but neutral detergent fiber TTD was greater for MOD versus HI and for 17 versus 24% fat. From 57 to 112 d, hip height change was greater for MOD versus HI, and hip width change was greater for 17 versus 24% fat. In this study, feeding Jersey calves more MR improved preweaning average daily gain, but had a negative effect on CSI and likely rumen development, as neutral detergent fiber TTD was reduced at 3 wk and frame growth was reduced from d 57 to 112. This resulted in similar final calf body weights between MR feeding rates at the end of the study. No benefits were observed for feeding more fat in MR as CSI or for NDF digestibility, and frame growth was reduced.

Starch-protein interaction in the rumen of weaned dairy calves.

The objectives of this study were to investigate the effect of starch and protein interaction on rumen environment, in situ digestion, and total-tract digestibility of nutrients in weaned dairy calves between 8 and 16 wk of age. Sixteen rumen-cannulated calves were randomly divided into 4 dietary treatment groups with 4 calves fed in each treatment. The treatment diets had 2 levels of starch [18%, low starch (LS), or 38%, high starch (HS)] and 2 levels of protein [16%, low protein (LP), or 22%, high protein (HP)] on a dry matter (DM) basis in calf grower: (1) LPLS, (2) LPHS, (3) HPLS, and (4) HPHS. Calves were fed for ad libitum intake (95% assigned grower and 5% grass hay), and refusals were collected weekly. Total-tract digestibility collection and in situ digestibility procedures were performed for each calf at 11 and 15 wk. Samples for in situ digestibility, grass hay (GH), soybean hulls (SBH), wheat middlings (WM), ground corn (GrC), and soybean meal (SBM) were incubated for 9 and 24 h. There was no starch and protein interaction on total-tract digestibility of calves. Total-tract DM, neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility, and feed efficiency were affected by both protein and starch inclusion level in calf diet. Total-tract starch digestibility was lower for LS diets. Dry matter digestibility and feed efficiency were greater in calves fed HP and HS diets compared with calves fed LP and LS diets, respectively. Fiber digestibility (NDF and ADF) was less in calves fed HS diets compared with calves fed LS diets but was greater in calves fed HP diets compared with calves fed LP diets. Level of protein did not affect in situ DM and NDF disappearance of GH, but HP increased in situ DM and NDF disappearance of SBH. High-starch diets decreased DM and NDF disappearance of both GH and SBH. At 20 h after feeding, ruminal pH was 0.51 unit higher in calves fed HPHS compared with calves fed LPHS. Total ruminal VFA and proportion of propionate was greater with HS versus LS, whereas proportion of acetate was greater with LS versus HS. The DM disappearance of SBM and WM and NDF disappearance of WM was greater for calves fed HPHS compared with calves fed LPHS at 11 wk of age. In our study, when HP was fed with HS, rumen pH, in situ digestion of WM and SBM, and total-tract digestion of DM, NDF, and ADF increased. This provides evidence for starch-protein interaction in the rumen of recently weaned dairy calves. Improvements in total-tract and in situ digestibility suggest that both protein and starch levels are important for 8- to 16-wk-old calves.

Models to predict dry feed intake in Holstein calves to 4 months of age.

Voluntary daily dry feed intake (DFI) in Holstein calves was predicted using 60,761 individual daily observations collected from 1,235 Holstein calves in 30 experiments from 4 research stations in the United States and Europe. Consumption of dry feed (calf starter and hay, kg/d or percent of body weight) was measured from 3 to 114 d of age. Linear models and 2- and 3-parameter nonlinear models were evaluated to predict DFI using age of calf, intake of milk replacer, ambient temperature, percent forage, and neutral detergent fiber concentration in ration dry matter (DM) as independent variables. The initial data set was randomly divided within study location into development (80% of all observations) and validation data sets, and initial screening was conducted using the development data set. Five nonlinear models and 3 linear models (candidate models) were identified and used in further model evaluation. Cross-validation studies (n = 20) with the validation data set were conducted by linear regression of DFI with predicted DFI as independent variable. Candidate models were subsequently evaluated with data from 12 published studies in 2 analyses. The exponential model that best predicted daily DFI in Holstein calves in original and external data sets was DFI (kg/d) = 1.3207 × e[(-5.3892 + 0.6376 × MEgap) × EXP(-0.0392 × Age)] - 0.0013 × Temp + 0.0032 × NDFDM + 0.0026 × Age × MEgap - 0.3646 × PctForage [coefficient of determination (R2) = 0.92, concordance correlation coefficient (CCC) = 0.96, and mean square error of prediction (MSEP) = 0.10 kg]; where MEgap (Mcal/d) = difference of daily metabolizable energy (ME) requirement and ME intake from milk replacer; Age = age of calf (d) from 3 to 114, Temp = mean daily ambient temperature (°C), NDFDM = ration neutral detergent fiber (% DM); PctForage = percent forage in ration DM. The linear model that best predicted DFI was DFI (kg/d = -0.1349 + 0.0106 × Age + 0.1808 × MEgap + 0.0013 × Age × MEgap + 0.0001 × Temp + 0.00002 × Age × Temp (R2 = 0.93, CCC = 0.96, and MSEP = 0.10 kg). When Temp and ration characteristics were not included, optimal models were 1.4362 × e[(-4.6646 + 0.5234 × MEgap) × EXP(-0.0361 × Age)] + 0.0025 × Age × MEgap (R2 = 0.92, CCC = 0.96, and MSEP = 0.11 kg) and -0.1344 + 0.0102 × Age + 0.1810 × MEgap + 0.0013 × Age × MEgap [R2 = 0.93, CCC = 0.96, and MSEP = 0.10 kg]. Models of daily DFI may improve prediction of nutrient supply to young Holstein calves to approximately 4 mo of age, thereby increasing prediction of growth performance.