Heng W Cheng

• MD, PhD
• Researcher at Purdue University West Lafayette

Numerous studies have evidenced that neuropsychiatric disorders (mental illness and emotional disturbances) with aggression (or violence) pose a significant challenge to public health and contribute to a substantial economic burden worldwide. Especially, social disorganization (or social inequality) associated with childhood adversity has long-last...

Injurious behaviors in laying hens are a critical issue facing the poultry egg industry. Recent studies have shown that the gut microbiota influences host brain function and behavioral characteristics in humans and various animals. In laying hens, it has been reported that injurious behaviors (such as aggression, feather pecking and cannibalism) ar...

Injurious behaviors (i.e., aggressive pecking, feather pecking, and cannibalism) in laying hens are a critical issue facing the egg industry due to increased social stress and related health and welfare issues as well as economic losses. In humans, stress-induced dysbiosis increases gut permeability, releasing various neuroactive factors, causing n...

The aim of this study was to examine effects of various daylight exposure during the 24-h light-dark (L-D) cycle on growth performance, skeletal health, and welfare state in broilers. Environmental photoperiod and related circadian clock, the 24-h L-D cycle, are important factors in maintaining productive performance, pathophysiological homeostasis...

Background Accumulating evidence from human trials and rodent studies has indicated that modulation of gut microbiota affects host physiological homeostasis and behavioral characteristics. Similarly, alterations in gut microbiota could be a feasible strategy for reducing aggressive behavior and improving health in chickens. The study was conducted...

High ambient temperature (heat stress, HS) is one of the critical environmental factors causing gut microbiota dysbiosis and increasing gut permeability, consequently inciting neuroinflammation in humans and various animals including chickens. The aim of this study was to examine if a probiotic, Bacillus subtilis, can reduce neuroinflammation in he...

Home cage aggression causes poor welfare in male laboratory mice and reduces data quality. One of the few proven strategies to reduce aggression involves preserving used nesting material at cage change. Volatile organic compounds from the nesting material and several body fluids not only correlate with less home cage aggression, but with more affil...

The aim of this study was to examine if synbiotics present similar efficiency to a common antibiotic used in poultry production under heat stress (HS) conditions. Two hundred and forty-one-day-old male Ross 708 broiler chicks were distributed among 3 treatments with 8 pens per treatment of 80 birds each for a 42-day trial. From day 15, birds were h...

Neuropsychiatry underlies personality development and social functioning. Borderline personality disorder exhibits high trait aggression and is associated with tryptophan hydroxylase polymorphisms. The acute tryptophan depletion reduces plasma and cerebrospinal fluid tryptophan availability and brain serotonin concentrations, leading to alterations...

The gut microbiota plays an important role in regulating brain function, influencing psychological and emotional stability. The correlations between conspecific aggression, gut microbiota, and physiological homeostasis were further studied in inbred laying chicken lines, 63 and 72, which were diversely selected for Marek’s disease, and they also be...

Nutrients and xenobiotics cross the blood–placenta barrier, potentially depositing in the fetal brain. The prenatal exposure affects the neuroendocrine and microbial development. The mechanism underlying maternal risk factors reprograming the microbiota–gut–brain axis with long-term effects on psychosocial behaviors in offspring is not clear. In hu...

Tryptophan, as the sole precursor of serotonin, mainly derived from diets, is essential for neurodevelopment and immunomodulation. Gestational tryptophan fluctuation may account for the maternal-fetal transmission in determining neuroembryogenesis with long-lasting effects on psychological development. Personality disorders and social exclusion are...

Recent studies have revealed that fecal microbiota transplantation exerts beneficial effects on modulating stress-related inflammation and gastrointestinal health of the host. The aim of this study was to examine if cecal microbiota transplantation (CMT) presents similar efficiency in improving the health status of egg-laying strain chickens. Chick...

Intestinal microbiota functions such as an endocrine organ to regulate host physiological homeostasis and behavioral exhibition in stress responses via regulating the gut–brain axis in humans and other mammals. In humans, stress-induced dysbiosis of the gut microbiota leads to intestinal permeability, subsequently affecting the clinical course of n...

Maternal metabolic disorder during early pregnancy may give rise to emotional and behavioral disorders in the child, vulnerable to bullying. Placental tryptophan fluctuation consequently disrupts offspring gut microbiome and brain neurogenesis with long-lasting physiological and social behavioral impacts. The aim of this study was to examine the hy...

The aim of this study was to examine if synbiotics can function as alternatives to antibiotics in broiler production under heat stress (HS). Day-old broiler chicks (528 birds) were randomly placed in floor pens within 2 identical temperature-controlled rooms (11 birds/pen and 24 pens/room). The pens of each room were evenly divided among 3 treatmen...

Heat stress is one of the most detrimental environmental challenges affecting the biological process and the related production performance of farm animals, especially in poultry. Commercial laying hens have been bred (selected) for high egg production, resulting in increased sensitivity to heat stress due to breeding-linked metabolic heat producti...

The elevation of ambient temperature beyond the thermoneutral zone leads to heat stress, which is a growing health and welfare issue for homeothermic animals aiming to maintain relatively constant reproducibility and survivability. Particularly, global warming over the past decades has resulted in more hot days with more intense, frequent, and long...

Long photoperiods are utilized in the broiler industry to maximize animal performance, though the impact on meat quality remains poorly understood. The current study evaluated the impact of photoperiod on functional/physicochemical properties and oxidative stability of meat through broiler processing. Ross 308 broilers (n = 432) were randomly assig...

The objective of this study was to evaluate the effects of photoperiod on meat quality, oxidative stability, and metabolites of broiler fillet (M. Pectoralis major) muscles. A total of 432 broilers was split among 4 photoperiod treatments [hours light(L):dark(D)]: 20L:4D, 18L:6D, 16L:8D, and 12L:12D. At 42 days, a total of 48 broilers (12 broilers/...

This article summarizes the design and performance of a cooled perch system for laying hens during heat stress. Water flow rates, perch loop water temperatures, and system net heat gain are provided. The average daily net heat absorption data, useful for sizing thermal water storage and chiller capacity in future applications, is 256 W m ⁻¹ perch l...

Objectives Prolonged photoperiod (light) is a common practice in the broiler industry to maximize feed intake, growth and yield. Several studies, however, have found negative impacts of extended photoperiod on animal welfare-related characteristics (e.g., leg abnormalities). While the previous research has primarily focused on animal growth/welfare...

Objectives In the broiler industry, high photoperiod (the duration of light exposure per day) regimes have traditionally been utilized to increase yield of breast meat, as well as maximize feed intake and growth rate in the growing period. However, recent literature reports this practice may have adverse effects on broiler welfare, resulting in imp...

This study examined effect of a dietary synbiotic supplement on the concentrations of plasma thyroid hormones, expressions of heat shock protein 70 (HSP70), and intestinal histomorphology in broiler chickens exposed to cyclic heat stress (HS). Three hundred and sixty day old male Ross 708 broiler chicks were randomly distributed among 3 dietary tre...

This study examined the effect of water-chilled perches on hen production and physiological responses to induced molt during elevated temperatures. A total of 288White Leghorns at 82 wk of age were housed in 36 cages of 6 banks. Each bank was assigned to 1 of 3 treatments: cooled perches, air perches, and no perches. The hens were subjected to 2 he...

The aim of this study was to examine the effect of a dietary synbiotic supplement on the cecal microflora, antioxidant status, and immune response of broiler chickens under heat stress (HS). A total of 360 one-day-old male Ross 708 broiler chicks were randomly distributed among 3 dietary treatments containing a synbiotic (PoultryStar consists of Bi...

We examined the effects of water-chilled perches as cooling devices on hen performance during 2 summers using daily cyclic heat. White Leghorns, 17 wk of age, were assigned to 36 cages arranged into 6 banks. The banks were assigned to cooled perches, air perches, and no perches resulting in 2 replicate banks and 12 cages per treatment. Chilled wate...

We assessed the effects of water-chilled perches as a cooling device on the physiological parameters of caged laying hens exposed to 2 cyclic heating episodes. White Leghorns, 17 wk of age, were randomly assigned to 36 cages of 6 banks placed in the same room. Each bank was randomly assigned to 1 of 3 treatments: cooled perch (CP), air perch (AP),...

The objective of this study was to determine the effects of a dietary synbiotic inclusion on broiler bone health under daily cyclic heat stress. A total of 360 Ross 708 broilers were randomly assigned to 1 of 3 dietary treatments (8 replicates per treatment): a regular diet (control) and the regular diet mixed with a commercial synbiotic product at...

The aim of the study was to assess the effects of dietary supplementation of a Bacillus subtilis based probiotic on broiler bone health. After 43 days, probiotic fed broilers had greater bone mineralization, wall thickness, size, and weight of tibias and femurs compared to the controls. We further found that probiotic fed broilers also had higher s...

The aim of this study was to determine the impact of probiotic feeding and chronic heat stress on meat quality, total lipid and phospholipid contents, lipid oxidation, antioxidant capacity, and heat shock protein abundance of broiler breast muscle. A total of 240 male broilers (5 birds per pen) were subjected to 4 treatments consisting of a 2 × 2 f...

Recent researches have showed that probiotics promote bone health in humans and rodents. The objective of this study was to determine if probiotics have the similar effects in laying hens. Ninety-six 60-week-old White Leghorn hens were assigned to four-hen cages based on their BW. The cages were randomly assigned to 1 of 4 treatments: a layer diet...

Probiotics reduce stress-related inflammation and abnormal behaviors in humans and rodents via regulation of the microbiota-gut-brain axis. The objective of this study was to determine if probiotic, Bacillus subtilis, has similar functions in broiler chickens under heat stress (HS). Two hundred forty 1-day-old broiler chicks were assigned to 48 pen...

Background and Objective: Probiotics modulate stress-induced changes of physiological homeostasis and behavioral exhibition through regulating the microbiota-gut-brain axis. The aim of this study was to assess if dietary supplementation of probiotic, Bacillus subtilis, reduces aggressive behaviors in laying hens following social challenge. Methodol...

This study examined the effects of a dietary synbiotic supplement on the behavioral patterns and growth performance of broiler chickens exposed to heat stress (HS). Three hundred sixty 1-day-old male Ross 708 broiler chicks were distributed among 24 floor pens (15 chicks per pen); each pen was randomly assigned to one of 3 dietary treatments contai...

This study was performed to evaluate the effect of probiotic feeding level on meat quality and protein functionality of breast muscle from chickens exposed to cyclic heat challenge. A total of 180 one-d-old male chicks were randomly allocated in 36 floor pens. From Day 15, the birds were exposed to 32°C for 10 h daily until the end of the experimen...

Background: The objective of this study was to evaluate effects of heat stress and probiotic supplementation on protein functionality and oxidative stability of ground chicken leg during display storage. Two hundred and forty 1-day-old male chicks (5 bird per pen) were subjected to four treatments in a 2 (thermoneutral condition at 21 °C and cycli...

Objective: This study aimed to examine the effect of dietary Brazilian propolis on the growth performance, physiological homeostasis and gut characteristics in broiler chickens reared under mild chronic heat stress. Materials and Methods: Five hundred and four 15 days old male broiler chicks were fed one of six diet (0.0, 100, 250, 500, 1000 and 30...

Nh3: Ammonia ( ) is a potential health hazard to both humans and animals, causing local and systemic low-grade inflammation based on its levels and exposure durations. The objective of this study was to examine the effects of 45 wk of exposure to 30 ppm NH 3 on the concentrations of acute-phase proteins, immunoglobulins, and cytokines in laying he...

Background and Objective: Ammonia (NH3) is one of the most prominent aerial pollutants inside poultry barns, affecting chicken health and well-being based on its level and exposure duration. The aim of this study was to investigate the effect of 30 ppm NH3 on the immune response of laying hens. Methodology: Hy-Line W-36 hens at 18 weeks of age were...

The study was conducted to determine the effects of probiotic supplementation and fast freezing on quality attributes and oxidation stability of frozen/thawed chicken breast muscle. Broilers (n = 168) were fed with a basal diet or the basal diet plus 250 mg of Sporulin (three strains of Bacillus subtilis)/kg of basal diet for 45 days. Pairs of brea...

We assessed the effects of chilled water cooling perches on hen performance and physiological and behavioral parameters under “natural” high temperatures during the 2013 summer with a 4-hour acute heating episode. White Leghorns at 16 wk of age (N = 162) were randomly assigned to 18 cages (n = 9) arranged into 3 units. Each unit was assigned to one...

In egg industry, transportations and mixing are common stressors for hens. The objective of this study was to determine if the dietary antioxidant supplement improves hen performance, egg quality and behavior following transportation and housing environment changes. At 28 week of age, floor pen housed Bovans Brown hens (n = 48) were transferred to...

[This corrects the article DOI: 10.1371/journal.pone.0141215.].

This study evaluated the effects of dietary probiotic supplement and postmortem storage on meat quality of chicken breast during retail display. A total of 35 birds were randomly obtained from 3 feeding groups (control without probiotic supplement, 250 ppm Sporulin, and 500 ppm PoultryStar). The probiotic supplement had no influence on feed convers...

Propolis is a resinous hive product collected by honeybees from various sources of plants. Numerous scientific investigations have been focused on the biological activities of propolis and its functions as a health supplement in humans. It could have similar function in other animals, such as in poultry. This review is focused on the recent finding...

The objective of this study was to determine if thermally cooled perches improve hen immunity during hot summer. White Leghorn pullets at 16 week of age were randomly assigned to 18 cages of 3 banks at 9 hens per cage. Each bank was assigned to 1 of the 3 treatments up to 32 week of age: 1) thermally cooled perches, 2) perches with ambient air, and...

Heat stress, as one of the environmental stressors affecting the dairy industry, compromises the cow milk production, immune function, and reproductive system. However, few studies have looked at how prenatal heat stress (HS) affects the offspring. The objective of this study was to evaluate the effect of HS during late gestation on calf immunity....

The wattles and comb of chickens are important for thermoregulation allowing for heat exchange during high temperatures. These integumentary tissues are sometimes trimmed to prevent tears if caught on cage equipment and to also improve feed efficiency; however, the procedure itself could be painful to chicks. Our objective was to determine the effe...

This experiment was conducted to evaluate the effects of dietary supplementation of green Brazilian propolis on behavioral patterns and feather condition of heat stressed broiler chickens. Five hundred and four (504) male Ross 708 broiler chicks at 15-day old were randomly allotted to six dietary treatments containing 0 (control), 100, 250, 500, 10...

This experiment evaluated the effect of dietary supplement with green Brazilian propolis on serum thyroxin (T4) and tri-iodothyronine (T3) levels in broiler chickens exposed to chronic heat stress for 4 wks (from 15 to 42 d of age). Five hundred and four 15-d-old, male broiler chickens (Ross 708) were randomly allocated to 6 treatments (4 pens/trea...

Exposing broiler chickens to heat stress increases leg abnormalities and gait score, also it reduced the time of Latency to Lie Test. This experiment was conducted to examine the effect of dietary supplemention with green Brazilian propolis on Latency to Lie Test for leg strength and leg abnormalities in broiler chickens exposed to chronic heat str...

This experiment evaluated the effect of dietary supplement with green Brazilian propolis on serum thyroxin (T4) and tri-iodothyronine (T3) levels in broiler chickens exposed to chronic heat stress for 4 wks (from 15 to 42 d of age). Five hundred and four 15-d-old, male broiler chickens (Ross 708) were randomly allocated to 6 treatments (4 pens/trea...

This experiment investigated effects of dietary supplementation of green Brazilian propolis on behavior of heat stressed broiler chickens. Five hundred and four 15-day old male Ross 708 broiler chicks were randomly allotted to six dietary treatments containing 0, 100, 250, 500, 1000 or 3000 mg kg-1 propolis. Each diet was fed to four replicates of...

As consumers and society in general become more aware of ethical and moral dilemmas associated with intensive rearing systems, pressure is put on the animal and poultry industries to adopt alternative forms of housing. This presents challenges especially regarding managing competitive social interactions between animals. However, selective breeding...

ABSTRACT: Improving piglet survivability rates is of high priority for swine production as well as for piglet well-being. Dysfunction in the serotonin (5-HT) system has been associated with growth deficiencies, infant mortalities, or failure to thrive in human infants. The aim of this research was to determine if a relationship exists between infan...

Propolis is a resin produced by honeybees (Extra Green Propolis, Apis Flora Co., São Paulo, Brazil) that has been implicated in induction of H2O2 generation by peritoneal MO and inhibition of NO, simulation of antibody production, and enhanced natural killer activity. TLR2 and TLR4 and interleukin (IL) 1 and 6 were enhanced in mice treated with pro...

Enriched cages, compared with conventional cages, allow egg laying strains of chickens to meet some behavioral needs, including a high motivation to perch. The objective of this study was to determine if perch availability during rearing affected perch use as adults and if perch presence affected eating and drinking in caged White Leghorn hens. Chi...

This experiment was conducted to examine the effect of dietary supplement with green Brazilian propolis on body weight (BW), weight gain (BWG) and cecal microflora in broiler chickens raised under heat stress condition. A total of 504 fifteen-d-old male broiler chickens (Ross 708) were randomly allocated to 6 treatments, each with 4 replicate pens...

Egg laying strains of chickens have a strong motivation to perch. Providing caged chickens with perches allows them to perform their natural perching behavior and also improves their musculoskeletal health due to exercise. Little is known about the effect of perch access for hens on physiological measures of stress. Our hypothesis was that denying...

Fatty liver is a common energy metabolic disorder in caged laying hens. Considering that the egg industry is shifting from conventional cages to alternative housing systems such as enriched cages, the objective of this study was to determine the effects of perches on fat deposition and liver health in laying hens. Three hundred twenty-four 17-wk-ol...

Heat stress (HS) causes oxidative damage, increasing mortality and reducing productivity in chickens. The objective of this study was to determine the benefits of antioxidant supplementation in laying hens during HS. Eighty 32-week-old W-36 White Leghorn hens were used in this study. Hens were randomly pair-housed in two adjacent rooms and fed a co...

Abstract 1. Serotonin (5-HT) is a primary regulating neurotransmitter involved in aggressive and impulsive behaviours in mammals. Previous studies have also demonstrated that the function of the serotonergic system in regulating aggression is affected by both genetic and environmental factors. The serotonergic system may display similar functions i...

After birth, piglets undergo procedures likely to cause stress. The aim of this study was to evaluate stress responses evoked by 2 combinations (More Stressful [all a] or Less Stressful [all b]) of alternative methods for performing: 1) teeth resection (TR) - [a] clip vs. [b] grind; 2) identification (ID) - [a] ear tag vs. [b] ear notch; 3) iron ad...

Heat stress in both mechanically and naturally ventilated egg production facilities is a problem for the egg industry. Various means of providing supplemental cooling to hens in facilities are available, including tunnel ventilation to increase convective losses and evaporative cooling from either pads or from misting (lower pressure) or fogging (h...

The neuroendocrine system controls animals' adaptability to their environments by releasing psychotropic compounds such as catecholamines [epinephrine (EP), norepinephrine (NE), and dopamine (DA)], corticosterone (CORT), and serotonin (5-hydroxytryptamine or 5-HT). Changes of these neuroendocrine compounds have been used as biomarkers of animals' s...

Osteocalcin (OC) is a sensitive biochemical marker for evaluating bone turnover in mammals. The role of avian OC is less clear because of the need for a chicken assay. Our objectives were to develop an assay using indirect competitive ELISA for detecting chicken serum OC and use the assay to examine the effects of perches on bone remodeling in cage...

A major skeletal problem of conventionally caged hens is increased susceptibility to osteoporosis mainly due to lack of exercise. Osteoporosis is characterized by a progressive decrease in mineralized structural bone. Whereas considerable attention has been given to enriching laying cages, little research has been conducted on providing caged pulle...

Studies have demonstrated that obesity and osteoporosis are linked disorders in humans. This study examined the hypothesis that excessive lipid consumption affects bone metabolism in laying hens. A total of one hundred 63-wk-old laying hens were randomly divided into 2 treatments and fed either a regular layer diet (control) or a high energy and lo...

Prenatal stress can alter the serotonin (5-HT) system in the developing and adult brain and lead to mood and behavioral disorders in children and adults. The chicken provides a unique animal model to study the effects of embryonic stressors on childhood and adolescent behavior. Manipulations to the egg can be made in the absence of confounding mate...

Genetic differences alter the type and degree of hens' responses and their ability to adapt to a stressor. This study examined the effects of genotypic variations on the productivity and behavior of laying hens following heat stress (HS). Two strains of White Leghorn hens were used: DXL (Dekalb XL), a commercial strain individually selected for egg...

Enrichment of pullet cages with perches has not been studied. Our objective was to determine if access to metal perches during all or part of the life cycle of caged White Leghorns affected egg traits, foot health, and feather condition. Treatment 1 represented control chickens that never had access to perches during their life cycle. Treatment 2 h...

Osteoporosis, a progressive decrease in mineralized structural bone, causes 20 to 35% of all mortalities in caged White Leghorn hens. Previous research has focused on manipulating the egg laying environment to improve skeletal health, with little research on the pullet. The objective of the current study was to determine the effect of perch access...

Infrared beak trimming provides an alternative to conventional trimming, purporting to provide a welfare-friendly means of trimming. The infrared system can be adjusted to use multiple plate and power settings. In the present study, we used 2 different plate sizes (27/23C, less severe; 25/23C, more severe) with each of 3 power settings: high (52),...

Heat stress (HS) is a major problem experienced by the poultry industry during high-temperature conditions. The ability to manage the detrimental effects of HS can be attributed to multiple factors, including genetic background of flocks. The objective of the present study was to determine the genetic variation in HS effects on laying hens’ physiol...

Aggression and cannibalism in laying hens can differ in intensity and degree due to many factors, including genetics. Previous behavioral analysis of 2 strains of White Leghorns, DeKalb XL (DXL) and HGPS (a group-selected line for high group productivity and survivability), revealed high and low aggressive phenotypes, respectively. However, the exa...

The dopaminergic system is involved in the regulation of aggression in many species, especially via dopamine (DA) D1 and D2 receptor pathways. To investigate heritable differences in this regulation, 2 high aggressive strains [Dekalb XL (DXL) and low group egg productivity and survivability (LGPS)] and one low aggressive strain (low group egg produ...

Dietary etiologies or treatments for complex mental disorder are highly controversial in psychiatry. Nevertheless, diet affects brain chemistry (particularly serotonin), and can reduce abnormal behavior in humans and animals. We formulated a diet that elevated brain serotonin and tested whether it would reduce hair pulling in a mouse model of trich...

This study examined the effects of infrared beak treatment (IR-BT) and hot blade beak trimming (HB-BT) on beak length and production in laying hen pullets. Seventy-two 1-d-old birds were randomly assigned to the HB-BT, IR-BT, or control group. Birds were pair housed by treatment, and beak images and production indices were obtained posttreatment at...

Aggression is a major source of social stress with negative effects on health and well-being, yet limited information is known about the molecular mechanisms mediating aggressive behavior in swine. Ractopamine (RAC) is a β-adrenoreceptor agonist that enhances growth but increases aggressive behaviors in female pigs. Thus, the effects of RAC, sex, a...

Under farm conditions, aggression related to the formation of social hierarchy and competition for resources can be a major problem because of associated injuries, social stress, and carcass losses. Any factor that may affect the regulation and amount of aggression within a farmed system, for instance, feeding the beta-adrenoreceptor agonist ractop...