Diagnostic yield of esophagogastroduodenoscopy in upper gastrointestinal bleeding in pediatrics: a cross-sectional study at a tertiary center

Background

Esophagogastroduodenoscopy (EGD) is currently considered the first-line diagnostic procedure of choice for upper gastrointestinal bleeding (UGIB); however, the etiology of bleeding remains unknown in a subset of patients. This study aimed to evaluate the diagnostic yield of EGD in UGIB in pediatrics and determine the clinical predictors for positive endoscopic diagnosis.

Methods

A cross-sectional study was conducted at the pediatrics endoscopy unit, Ain Shams University, Cairo, Egypt, where 100 children were included. They were referred for EGD due to overt UGIB in the form of hematemesis and/or melena. Full medical history, thorough physical examination, laboratory investigations, and endoscopic and histopathologic findings were documented.

Results

Forty-seven males and 54 females were included. Their ages ranged from 3 months to 15 years, with a median age of 4 years. Sixty-five percent presented with hematemesis only, 7% presented with melena only, and 28% presented with hematemesis and melena. An endoscopic diagnosis could be reached in 62% of cases, with Helicobacter pylori (H. pylori) gastritis (23%) and reflux esophagitis (11%) as the most common endoscopic diagnoses, with the former being the most common in children above 4 years and the latter for younger ones. Other diagnoses included non-specific gastritis (8%) and esophageal varices (4%). Presentation with melena only was a negative predictor to reach a diagnosis by EGD, while splenomegaly and thrombocytopenia were independent predictors of variceal bleeding.

Conclusion

EGD is the investigation of choice in children suffering from hematemesis especially in older age groups. Clinical and laboratory parameters might help in the prediction of the underlying etiology.

The role of rectal ultrasound in children with functional constipation

AIM

The study aimed primarily to compare the transverse rectal diameter in children with functional constipation (FC) and children without constipation in different age groups, and between cases of constipation at baseline and after treatment. Secondary aim was to determine factors that could affect the transverse rectal diameter.

METHODS

A controlled prospective study, including a total of 100 children between the ages of 2 and 11 years, who were divided into 50 patients suffering from constipation according to Rome IV criteria and 50 age- and sex-matched controls. Transverse rectal diameter was measured at presentation, and after 3 months of laxative therapy and behavioural modification.

RESULTS

Initial rectal diameter was significantly different between cases (3.55 cm (interquartile range, IQR), 3.2-4) and controls (2.3 cm (IQR, 1.8-2.5)), P value < 0.001, and it was also significantly different between those above and below 4 years, so a separate cut-off point for diagnosis of constipation was suggested being >3 cm for the former and >2.5 cm for the latter. After 3 months of follow-up, rectal diameter significantly reduced to become 2.6 (IQR, 2-2.8), P value < 0.001. Duration of symptoms positively correlated with rectal diameter.

CONCLUSIONS

Ultrasound measurement of rectal diameter is an important tool to diagnose and follow-up functional constipation in children. Different values of rectal diameter are found between those above and below 4 years of age.

First-in-human dose escalation study of cyclin-dependent kinase-9 inhibitor VIP152 in patients with advanced malignancies shows early signs of clinical efficacy

PURPOSE

To report on the first-in-human phase I study of VIP152 (NCT02635672), a potent and highly selective CDK9 inhibitor.

PATIENTS AND METHODS

Adults with solid tumors or aggressive non-Hodgkin lymphoma (NHL) who were refractory to or had exhausted all available therapies received VIP152 monotherapy as a 30-minute intravenous, once weekly infusion, as escalating doses (5, 10, 15, 22.5, or 30 mg in 21-day cycles) until the maximum tolerated dose (MTD) was determined.

RESULTS

Thirty-seven patients received {greater than or equal to} 1 VIP152 dose, with 30 mg identified as the MTD based on dose-limiting toxicity of grade 3/4 neutropenia. The most common adverse events were nausea and vomiting (75.7% and 56.8%, respectively), all of grade 1/2 severity. Of the most common events, Grade 3/4 events occurring in > 1 patient were neutropenia (22%), anemia (11%), abdominal pain (8%), increased alkaline phosphatase (8%), and hyponatremia (8%). Day 1 exposure for the MTD exceeded the predicted minimum therapeutic exposure and reproducibly achieved maximal pathway modulation; no accumulation occurred after multiple doses. Seven of 30 patients with solid tumors had stable disease (including 9.5 and 16.8 months in individual patients with pancreatic cancer and salivary gland cancer, respectively), and 2 of 7 patients with high-grade B-cell lymphoma with MYC and BCL2/BCL6 translocations (HGL) achieved durable complete metabolic remission (ongoing at study discontinuation, after 3.7 and 2.3 years of treatment).

CONCLUSION

VIP152 monotherapy, administered intravenously once weekly, demonstrated a favorable safety profile and evidence of clinical benefit in patients with advanced HGL and solid tumors.

MO1025SCREENING FOR CELIAC DISEASE AMONG PEDIATRIC PATIENTS WITH CHRONIC KIDNEY DISEASE

Background and Aims

Chronic kidney diseases (CKD) in children are a group of diseases that not only affects the kidneys but also all systems of the body particularly causing anemia, bone diseases and failure to thrive in that age group. Gastrointestinal tract (GIT) manifestations are not thoroughly highlighted in those patients although they definitely have repercussions on their growth and development. GIT diseases such as celiac disease (CD) has been long linked to renal manifestations either through increasing risk of kidney diseases or as a proved association. The aim of this study was screening for celiac disease and GIT symptoms among pediatric patients with chronic kidney disease.

Method

A case-control study included 90 CKD patients from Nephrology unit, Children’s Hospital, Ain Shams University, who has been diagnosed for at least 3 months and not receiving steroids or immunosuppressive therapy: 60 patients with end stage renal disease (ESRD) on regular hemodialysis (HD) & 30 with CKD on conservative treatment. Their ages ranged between 2-13 years old, 47 males, 43 females. 200 controls were also enrolled in the study (for GIT manifestations): healthy children with ages ranging from 2-13 years old, 77 males, 123 females within a period of 12 months. All patients & controls were interviewed about GIT manifestations they regularly experience and any GIT troubles they have. All CKD patients were screened for CD by Anti Tissue transglutaminase IgG and IgA blood testing.

Results

Reviewing the most significant GIT symptoms among patients, we found that 86.7% had mucoid diarrhea, 77.8% had abdominal distension, 75.6% had anorexia, 64.4% had epigastric pain, 51.1% had watery diarrhea, 30% had nausea, 30% had vomiting, and 25.6% had constipation. None suffered from hematemesis, melena or bloody diarrhea. GIT symptoms were significantly more pronounced in CKD patients compared to controls and even more in ESRD patients than CKD patients. All patients were negative for CD screening by Anti Tissue transglutaminase IgG and IgA. No significant correlations were seen between Anti Tissue transglutaminase IgG and IgA and age, sex, anthropometric measures (except for BMI), biochemical results (except for s. ferritin) or eitiology of renal disease were observed.

Conclusion

GIT troubles are more pronounced in children with CKD compared to age and sex matched healthy controls. CD is not particularly prevalent among CKD pediatric patients compared to the known percentage among this age population.

Safety and efficacy of VIP152, a CDK9 inhibitor, in patients with double-hit lymphoma (DHL)

7538

Background: PTEFb/CDK9-mediated transcription of short-lived anti-apoptotic survival proteins and oncogenes like MCL-1 and MYC plays a critical role in a variety of cancers. VIP152 (formerly BAY 1251152), a potent and highly selective CDK9 inhibitor, has been evaluated in a Phase 1 dose-escalation study in patients with advanced cancer. The maximum tolerated dose was 30 mg once weekly administered in consecutive 21-day cycles, based on neutropenia as the dose-limiting toxicity (JCO 2018;36:2507; NCT02635672). DHL is defined as dual rearrangement of the MYC gene and either the BCL2 or BCL6 genes; the resulting overexpression of MYC and BCL2/BCL6 make it particularly difficult to treat. Patients with DHL have a poor prognosis and no standard of care. Considering the impact of CDK9 inhibition on MYC, an exploratory cohort of patients with DHL was added to the study. Methods: Patients with refractory or relapsed DHL were eligible. VIP152 was administered once weekly as a 30-minute IV infusion on Days 1, 8 and 15 of a 21-day cycle. Tumor response was assessed according to the revised Cheson criteria (2007). Results: To date a total of 7 patients have been enrolled and were evaluable at the time of data cutoff (24NOV2020). The patients were mostly men (6/7 pts, 86%) with a median (range) age of 70 (58-84) years. All patients received ≥2 prior therapies, including 2 patients with bone marrow transplant. Three of 7 patients (29%) had ≥3 prior therapies. The median time on treatment was 22 days (range 8-1361 days). The most common adverse events of any grade were: constipation, fatigue, nausea (each 3/7 pts, 43%) and abdominal pain, diarrhea, lymphocyte count decrease, neutrophil count decrease, skin infection, tumor pain, and vomiting (each 2/7 pts, 29%). Most were Grade 1 and Grade 2. The Grade 3 adverse events were fatigue, lymphocyte count decrease, neutrophil count decrease (each 1/7 pts, 14%) and tumor pain (2/7 pts, 29%). One Grade 4 lymphocyte count decrease was reported. Two patients had a serious adverse event (Grade 3 syncope and Grade 3 tumor pain). Two patients had dosing held for an adverse event; however, no patient withdrew from treatment due to any adverse events. One death occurred due to disease progression. Pharmacodynamic biomarker analysis showed significant reduction of MYC, PCNA, and MCL-1 mRNA in all patients across multiple timepoints. Antitumor activity consisted of 2 complete metabolic responses in 7 patients (29%) based on investigator-assessed FDG-PET scans. Due to the COVID pandemic, the patients withdrew consent after 3.7 and 2.3 years, respectively, of treatment. Both patients were in complete metabolic response. Conclusions: VIP152 had a manageable safety profile, on-target pharmacodynamic activity and signs of durable monotherapy antitumor activity in patients with DHL. These encouraging results warrant further evaluation of VIP152 in patients with MYC-driven lymphoma and solid tumors. Clinical trial information: NCT02635672.

Pooled analysis of safety data from clinical trials evaluating acalabrutinib monotherapy in mature B-cell malignancies

Bruton tyrosine kinase (BTK) inhibition is an effective therapy for many B-cell malignancies. Acalabrutinib is a next-generation, potent, highly selective, covalent BTK inhibitor. To characterize acalabrutinib tolerability, we pooled safety data from 1040 patients with mature B-cell malignancies treated with acalabrutinib monotherapy in nine clinical studies (treatment-naïve: n = 366 [35%], relapsed/refractory: n = 674 [65%]; median [range] age: 67 [32-90] years; median [range] prior treatments: 1 [0-13]; median [range] duration of exposure: 24.6 [0.0-58.5] months). The most common adverse events (AEs) were headache (38%), diarrhea (37%), upper respiratory tract infection (22%), contusion (22%), nausea (22%), fatigue (21%), and cough (21%). Serious AEs (SAEs) occurred in 39% of patients; pneumonia (6%) was the only SAE that occurred in ≥2%. Deaths due to AEs occurred in 52 patients (5%); pneumonia (n = 8) was the only fatal AE to occur in ≥3 patients. AEs led to treatment discontinuation in 9%. Rates for the AEs of interest (all grades) included infections (67%), hemorrhages (46%), neutropenia (16%), anemia (14%), second primary malignancies (12%), thrombocytopenia (9%), hypertension (8%), and atrial fibrillation (4%). This pooled analysis confirmed acalabrutinib's tolerability and identified no newly emerging late toxicities, supporting acalabrutinib as a long-term treatment for patients with mature B-cell malignancies.

Enhancement of low-fat Feta cheese characteristics using probiotic bacteria

The objective of this study was to manufacture low-fat Feta cheese (LFC) using different types of starter cultures, such as yogurt (Y) cultures (Streptococcus thermophilus and Lactobacillus bulgaricus), bifidobacterium (B) cultures (Bifidobacterium bifidum and Bifidobacterium longum), and mixed of them (Y + B) at different rates (0.4, 0.5, and 0.6%). The Y + B cultures improved the flavor and body and texture of LFC, especially at a ratio of 0.4 + 0.6% and 0.5 + 0.5%, which is similar to the typical full-fat Feta cheese. Also, the LFC maintained a higher number of probiotics and lactic acid bacteria after 30 d of storage at a range of 5 to 7 log cfu/g.

Acalabrutinib in treatment-naïve chronic lymphocytic leukemia: Mature results from phase II study demonstrating durable remissions and long-term tolerability

8024

Background: The next-generation Bruton tyrosine kinase inhibitor acalabrutinib was approved in patients (pts) with treatment-naïve (TN) and relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) based on two complementary phase 3 studies, ELEVATE-TN and ASCEND. This report of ACE-CL-001 (NCT02029443), the first phase 2 study of acalabrutinib, provides the longest safety and efficacy follow-up to date in symptomatic TN CLL pts. Methods: Adults with TN CLL/SLL were eligible if they met iwCLL 2008 criteria for treatment, were inappropriate for/declined standard chemotherapy and had ECOG performance status 0–2. Pts received acalabrutinib 100 mg BID or 200 mg QD, later switching to 100 mg BID, until progressive disease (PD) or unacceptable toxicity. Primary endpoint was safety. Events of clinical interest (ECI) were based on combined AE terms for infections, bleeding events, hypertension, and second primary malignancies (SPM) excluding non-melanoma skin, and on a single AE term for atrial fibrillation. Additional endpoints included investigator-assessed overall response rate (ORR), duration of response (DOR), time to response (TTR), and event-free survival (EFS). Results: Ninety-nine pts (n = 62 100 mg BID; n = 37 200 mg QD), were treated [median age: 64 years, 47% Rai stage 3–4 disease, 10% del(17p), 62% unmutated IGHV]. At median follow-up of 53 months (range, 1–59), 85 (86%) pts remain on treatment; most discontinuations were due to AEs (n = 6) or PD (n = 3 [n = 1 Richter transformation]). Most common AEs (any grade) were diarrhea (52%), headache (45%), upper respiratory tract infection (44%), arthralgia (42%), and contusion (42%). All-grade and grade ≥3 ECIs included infection (84%, 15%), bleeding events (66%, 3%), and hypertension (22%, 11%). Atrial fibrillation (all grades) occurred in 5% of pts (incidence: 1% in years 1, 2, 4; 3% in year 3). SPMs excluding non-melanoma skin (all grades) occurred in 11%. Serious AEs were reported in 38% of pts; those in > 2 pts were pneumonia (n = 4) and sepsis (n = 3). ORR was 97% (7% complete response; 90% partial response). Median TTR was 3.7 months (range, 2–22). Response rates were similar across high-risk groups. Median DOR and median EFS were not reached; 48-month DOR rate was 97% (95% CI, 90%–99%), and 48-month EFS rate was 90% (95% CI, 82%–94%). Conclusions: Long-term data from ACE-CL-001 further support the favorable results with acalabrutinib in phase 3 studies and demonstrate durable responses with no new long-term safety issues. Clinical trial information: NCT02029443 .

Acalabrutinib with obinutuzumab (Ob) in treatment-naive (TN) and relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL): Three-year follow-up

7500

Background: Acalabrutinib is a highly selective, potent, covalent Bruton tyrosine kinase inhibitor. This Phase 1b/2 trial evaluated acalabrutinib with the CD20 antibody Ob in TN and R/R CLL. Methods: Patient (pts) with TN and R/R (≥1 prior therapy) CLL were eligible. In 28-day cycles, acalabrutinib was given at 100 mg BID or 200 mg QD PO (n=15; all switched to 100 mg BID) until progressive disease (PD); Ob was given in standard fashion for 6 cycles starting with Cycle 2. The primary endpoints were overall response rate (ORR) and safety. Minimal residual disease (MRD) was assessed using flow cytometry (sensitivity 10-4). Results: 19 TN and 26 R/R pts were treated; median age of all pts was 61 y (range 42-76). Pt characteristics, disposition, efficacy and MRD are in the Table. Common adverse events (AEs; any grade) were upper respiratory tract infection (71%), increased weight (71%), maculopapular rash (67%), cough (64%), diarrhea (62%), headache (56%), nausea (53%), arthralgia (51%) and dizziness (47%). Common Gr 3/4 AEs were decreased neutrophil count (24%), syncope (11%), decreased platelet count, increased weight and cellulitis (9% each). There were 2 (4%) Gr 3 bleeding events (hematuria, muscle hemorrhage) and 1 (2%) Gr 3 atrial fibrillation event. Conclusions: Acalabrutinib plus Ob was well tolerated and yielded high response rates that were durable and deepened over time in TN and R/R CLL patients. Clinical trial information: NCT02296918. [Table: see text]

Vitamin D Increases Percentages of Interleukin-10 Secreting Regulatory T Cells in Children with Cow's Milk Allergy

Cow's milk allergy (CMA) is known to be either IgE- or non-IgE mediated. Regulatory T (Treg) cell defect is involved in the pathogenesis of both types. Vitamin D has been suggested to improve the generation of allergen-specific Treg cell populations with the potential to provide safe and long-term alleviation of disease symptoms. This study aimed to assess Vitamin D status in children with physician-diagnosed CMA and to investigate the effect of in vitro cultivation with Vitamin D on the percentage of antigen-driven CD4+CD25highFoxp3+IL10+ Treg cells following in vitro stimulation of cells with cow's milk allergen in culture. This cross-sectional study included 20 children with CMA and 20 healthy age and sex-matched children as a control group. All patients were subjected to clinical evaluation, cow's milk skin prick test (SPT), cow's milk elimination and oral re-challenge test in patients with negative cow's milk SPT and in those with gastrointestinal presentation, measurement of serum Vitamin D level and assessment of the percentage of antigen-driven CD4+CD25highFoxp3+IL10+ Treg cells in response to stimulation with cow's milk allergen extract with and without Vitamin D in culture. Vitamin D deficiency was detected in 80% of children with CMA. Percentage of Foxp3+ and IL10+ co-expression on Treg cells was significantly increased after stimulation with cow's milk allergen extract in the presence of Vitamin D. A significant positive correlation was observed between serum Vitamin D level and percentage of antigen-driven CD4+CD25highFoxp3+IL10+ Treg cells as well as level of Foxp3+ and IL10+ co-expression on Treg cells at baseline (control cultures without stimulation) and after PBMCs stimulation with cow's milk allergen extract in the presence of Vitamin D. Re-stimulation with cow's milk allergen extract was performed in vitro in order to evaluate milk-induced immune stimulation and regulation. In conclusion, patients with CMA whether IgE- or non-IgE mediated had Vitamin D deficiency with a decreased number of CD4+CD25highFoxp3+IL10+ Treg cells which increased after in vitro addition of Vitamin D with increased Foxp3 and IL10 co-expression.

Rectal bleeding in Egyptian children

AIM

In a prospective study to outline the aetiology of bleeding per rectum (BPR) in Egyptian infants and children, a subsidiary aim was to define some of the clinical characteristics of the different aetiologies.

SUBJECTS AND METHODS

194 children with BPR are described. The diagnostic work-up included laboratory investigations, radiological and endoscopic assessment, radio-isotope scanning, angiography and histopathological examination of mucosal biopsies, as appropriate.

RESULTS

Ages ranged from 3 to 192 months with a mean (SD) of 49.8 (43.5). Infectious enterocolitis was the most common cause (37.1%). Others included colorectal polyps (21.1%), chronic colitis (16%) including inflammatory bowel diseases (5.2%), allergic colitis (2.6%), solitary rectal ulcer syndrome (1.5%) and non-specific colitis (6.7%). Intussusception and Meckel's diverticulae were the cause in 7.3% and 2.6%, respectively, while other aetiologies included vascular (6.2%), systemic (3.6%), local anal (3.1%) and upper gastro-intestinal causes (1.5%). In 1.5% of cases, the cause remained 'obscure'.

CONCLUSION

In Egyptian children, infectious enterocolitis followed by colorectal polyps and chronic colitis are major causes of BPR.

Phase I/II study of PCI-27483, a coagulation factor VIIa (FVIIa) inhibitor, in combination with gemcitabine in patients with advanced pancreatic cancer

e15014

Background: Tissue factor (TF) up-regulation is associated with increased tumor invasiveness and progression, worsened prognosis and increased thromboembolism (VTE). Activation of protease activated receptors by TF:FVIIa complex leads to increases in IL-8, VEGF and other invasiveness promoting factors. PCI-27483 (P), a selective FVIIa inhibitor, reduced pancreatic adenocarcinoma (PCa) xenograft growth in mice at doses producing 2.5 - 3.0 x PT changes. Methods: Escalating doses of P combined with gemcitabine (G) targeting peak (2 hr post) INR = 3.0 was studied in Phase I preceding randomization to G+P at the determined dose vs. G alone in Phase II. Eligible patients (pts) had measurable locally advanced or metastatic PCa, ECOG PS 0-1, and normal PT/aPTT, and no history of VTE. G was given IV at 1 G/m2 q wk X3 every 4 wks, and P was self-administered SC bid continuously. Tumor evaluation including spiral CTs were performed at baseline and q 8 wks. Results: In phase I, 8 pts were enrolled and the targeted INR was attained at 1.2 mg/kg. In phase II, 34 patients were randomized, 16 to G and 18 to G+P. The randomized arms were well balanced; overall 88% had metastatic disease; most had liver involvement. Among pts randomized to P+G, mean ± SD 2-hr post injection INR was 3.1 ± 1.2 on D8 and 2.8 ± 1.0 on D22 (n=13). P dosing was continued for up to 96 wks; mean ± SD: 17 ± 24 wks. Dose reduction to maintain target INR was required for 6 pts. Overall tolerability and safety of G+P was similar to that of G, with a higher incidence of mostly low grade bleeding events and decreased Hgb. Efficacy measures of G vs G+P pts were not significantly different (Table). Conclusions: PCI-27483 +G was well tolerated at doses of P up to 1.5 mg/kg bid. The safety profile of the combination was consistent with that expected of each agent. While the clinical endpoints were not achieved in pancreatic cancer, the targeted inhibition of the coagulation cascade was achieved. Clinical trial information: NCT01020006. [Table: see text]

Effect of passive smoking on blood lymphocyte apoptosis in children

BACKGROUND

Passive smoking is a well-known risk factor for both recurrent respiratory infections and disturbed lipid profile. Whether passive smoking problems are related to altered lymphocyte survival and its relation to altered lipid profile are the points of concern in this work.

MATERIALS AND METHODS

Urinary cotinine and creatinine levels as well as lipid profile and flow cytometric assessment of apoptosis of peripheral blood lymphocytes (PBL) were assessed in 26 children with history of indoor exposure to cigarette smokers in comparison with 14 matched children with no such history.

RESULTS

Lipid profile showed significantly higher mean levels of triglycerides, cholesterol and low-density lipoprotein (LDL) and significantly lower mean levels of high-density lipoprotein (HDL) in passive smoking children compared to nonpassive-smoking ones. Furthermore, cotinine parameters were positively correlated with triglycerides and LDL and negatively correlated with HDL. Early apoptosis of PBL was significantly higher in exposed vs nonexposed ones.

CONCLUSIONS

Passive smoking in children could be a risk factor for enhanced lymphocytic apoptosis. It is possible that altered lipid profile may play a role in the increased risk. The impact of this lymphocytic derangement on increased frequency of infections is noticeable.

Fate and ultra-structural features of chicken skin mucosa around juvenile polyps

OBJECTIVE

Chicken skin mucosa (CSM) is a common finding around juvenile polyps in children. Its ultrastructural features and fate after polypectomy are not yet clear. The aim was to study ultra-structural features and outcome of this CSM compared to that of the polyps and distant endoscopically normal mucosa.

MATERIAL AND METHODS

From 240 children with juvenile polyps, 45 needed a second colonoscopy. Thirty six patients showing CSM represented the cohort of this study. One polyp only was studied in each patient. The histologic features of the CSM were compared to normal and polyp mucosa. The fate of CSM was evaluated in the second colonoscopy.

RESULTS

The mean numbers of intraepithelial lymphocytes, as well as lamina propria inflammatory cellular infiltrates were significantly higher in polyp mucosa than in CSM. Goblet cells were significantly higher in CSM compared to normal mucosa with marked depletion in the polyp mucosa. The muscularis mucosae thickness was significantly higher in CSM compared to polyps (p<0.0001) and both showed higher values than the normal mucosa. The CSM almost disappeared within a month period following polypectomy.

CONCLUSIONS

The polyp showed the most intense mucosal inflammatory reaction. CSM with the unique thickening of muscularis mucosae especially around larger polyps almost disappeared after polypectomy. So these results suggest that CSM is a benign compensatory reaction induced by the mechanical effect of the polyp.

Effects of air humidity during incubation and age after hatch on heat tolerance of neonatal male and female chicks

Effects of incubation 45 versus 55% relative humidity (RH) and early versus late hatching time on heat tolerance of neonatal male and female chicks were studied. Chicks were exposed for 48 h to temperatures of 35 (Experiment 1), 37 (Experiment 2), or 39 C (Experiment 3). Chicks that hatched from eggs incubated at 45% RH were lighter at hatch than chicks that hatched from eggs incubated at 55% RH. Chicks that hatched from eggs incubated at 55% RH lost more body weight and water during heat exposure than those that hatched from eggs incubated at 45% RH. Body weight and water loss during heat exposure of chicks that hatched early and late was similar. However, chicks that hatched late maintained their initial heat production and respiratory quotient better during heat exposure than chicks that hatched early. Body weight and water loss of male and female chicks was similar. At 37 and 39 C, heat production of chicks fell to lower values during the 2nd day of exposure compared with the 1st day. It was concluded that chicks that hatched late, i.e., with a short holding period in the hatcher, and coming from eggs incubated at 45% RH had increased heat tolerance in comparison with the other chicks.

Effects of incubation humidity and hatching time on heat tolerance of neonatal chicks: growth performance after heat exposure

Three experiments were performed with 300 neonatal Hisex Brown layer chicks in each. The chicks hatched from eggs incubated at a relative humidity (RH) of 55 or 45%. Within each RH group, two groups were separated based on hatching time (early and late hatch groups). After hatch, 60 chicks served as controls. The other chicks were exposed to 35, 37, or 39 C for 48 h. After exposure, a 4-wk experimental growing period started at Day 2 of age. Chicks exposed to the experimental temperature regimens for 2 days had lower body weights at the end of exposure and grew less than controls during the 1st wk afterwards. At Day 2 of age, chicks hatched from eggs incubated at 45% RH had higher body weights than chicks hatched from eggs incubated at 55% RH. These chicks also had higher body weight gain in the 1st and 2nd wk following exposure to 39 C than chicks hatched from eggs incubated at 55% RH. Chicks hatching late were heavier at Day 2 than early-hatching ones, but body weight gain was similar. Chicks exposed to the experimental temperature regimens had lower rectal temperatures than controls at the end of the 1st and 2nd wk. Incubation RH, hatching time, and sex did not affect feed intake, feed conversion, or rectal temperature. After exposure to 39 C, fewer chicks that had hatched from eggs incubated at low RH died compared with chicks that had hatched from the 55% RH group. Early-hatching chicks had a significantly higher risk of dying than late-hatching ones.