About

Ramon Malheiros is an Assistant Professor in the Prestage Department of Poultry Science at NC State University. He earned his bachelor’s and master’s degrees from Federal University of Minas Gerais (UFMG), Brazil, and his Ph.D. from São Paulo State University (UNESP), Brazil. He also completed postdoctoral research at the Laboratory of Physiology of Domestic Animals at KUL in Belgium and at NC State University in the United States. His research focuses on broiler breeders' physiology and management, evaluating alternative feed ingredients, new feed additives, and incubation parameters. His work investigates how these factors influence animal growth, carcass development, intestinal health, blood biochemistry, rooster sperm quality, animal performance during production, egg quality, fertility, incubation parameters, embryo development, and hatchability.

Research topics

• Biology
• Animal science
• Food science
• Chemistry
• Internal medicine

Selected publications

• Determining how different ventilation shutdown plus methods change the electroencephalography, blood chemistry, corticosterone, and heat shock protein 70 of laying hens

  Frontiers in Physiology · 2025-03-21

  articleOpen access

  The poultry industry faces a major impediment in dealing with highly pathogenic avian influenza (HPAI). Large outbreaks have resulted in depletion of available resources needed for desired depopulation methods, leading to the need for alternative methods. This study was conducted to explore alternative ventilation shutdown procedures and how they affect laying hens throughout the process. Three treatments evaluated were ventilation shutdown plus heat (VSDH), ventilation shutdown plus heat and relative humidity (VSDHRh), and ventilation shutdown plus carbon dioxide (VSDCO 2 ). There were two phases used: one phase was used to study treatment effects on the hens’ EEG responses from beginning to time of death and how laying hens behaved. Phase 2 examined how these treatments affected hen blood chemistry and HSP70 during the process. VSDCO 2 had a significantly quicker time of death (P = 0.0003), and VSDH and VSDHRh were not different. There were no differences in pre- or post-corticosterone levels in Phase 1; however, there was a trend (P = 0.07) toward significance in the post corticosterone levels. Heat shock protein 70 (HSP70) levels were higher (P = 0.0001) in the VSDCO 2 treatment, which could be due to the protein upregulation to prevent apoptosis. In Phase 2, VSDH corticosterone had a significantly greater treatment effect compared to VSDHRh and VSDCO 2 . corticosterone levels were significantly greater than those of VSDHRh. There were no significant treatment effects in Phase 2 for HSP70 expression; however, the sequence was significant, with the HSP70 being significantly greater at 75% to the average time of death than at 100% to the average time of death. Overall, VSDHRh could be a good alternative for the industry to use to rapidly depopulate laying hen facilities. However, more research on this treatment and more in-depth stress parameters measured needs to be conducted to fully determine how it affects laying hens.

  PublisherOA PDFDOI

• Meat quality of hens fed an unblanched, high-oleic peanut diet

  Poultry Science · 2025-12-09 · 1 citations

  articleOpen access

  High-oleic peanuts are an energy-dense, protein-rich alternative to conventional poultry feed ingredients and may have an impact on meat quality in spent laying hens, which are typically diverted to low-value uses. This study evaluated the effects of unblanched high-oleic peanuts at five levels (0 %, 5 %, 10 %, 15 %, 20 %) into layer diets for 8 wks on carcass traits, meat composition, physicochemical properties, lipid stability, and sensory quality of spent layers. Diets were isonitrogenous (18 % crude protein) and isocaloric (3,080 kcal/kg metabolizable energy). A total of 200 hens were acclimated for 7 days, then randomly assigned to treatments (n = 5 replicates of 8 hens each). Ten hens per treatment were processed to assess body weight, carcass yield, breast meat pH, color, texture profile, water-holding capacity, proximate composition, lipid oxidation, and sensory attributes. Peanut inclusion up to 20 % did not adversely affect growth performance or carcass yield (P > 0.05). Meat pH and color were influenced in some dietary treatments, though all values remained within acceptable ranges for commercial meat. Moderate inclusion (10-15 %) greatly increased breast meat protein content, reduced fat and collagen levels, and improved moisture retention (P < 0.05), indicating enhanced nutritional quality and processing potential. Water-holding capacity parameters (purge, thaw, cook loss) were not different among treatments (P > 0.05). Likewise, texture profile attributes did not differ (P > 0.05) from control values. Lipid oxidation remained low and stable during extended frozen storage, consistent with the oxidative stability conferred by the peanuts' high oleic acid and polyphenol content. Sensory evaluation indicated that flavor, texture, and overall acceptability remained consistent across treatments (P > 0.05), with no evidence of rancidity, bitterness, or off-flavor development, even at the highest inclusion level. These results demonstrate that unblanched high-oleic peanuts can be incorporated into poultry diets at 10-15 % to enhance spent layer meat composition and maintain sensory quality, offering a sustainable, value-added strategy for improving the marketability of spent laying hens.

  PublisherDOI

• The comparative effects of ventilation shutdown with heat (VSDH), relative humidity (VSDHRh), or CO2 (VSDCO2) on broiler electroencephalogram (EEG), blood chemistry and gene expression

  The Journal of Applied Poultry Research · 2025-04-11

  articleOpen access

  Highly Pathogenic Avian Influenza (HPAI) outbreaks have highlighted major needs for multiple effective depopulation methods across all sectors and housing systems in the commercial poultry industry. Ventilation shutdown plus heat (VSDH), heat and relative humidity (VSDHRh), and carbon dioxide (VSDCO 2 ) were analyzed to understand how these methods affect broiler stress parameters and behavior. Two phases were used with both phases being conducted in sealable Plexiglass® chambers. Phase 1 (P1) analyzed electroencephalogram (EEG) of each broiler in each treatment along with blood chemistry, corticosterone, and heat shock protein 70 (HSP70) at time of death (TOD). Phase 2 (P2) looked at the progression of the stress parameters over time with specific physiological points when birds were removed from their respective chamber. There was a significant difference (P<0.0001) between time of death (TOD) with VSDCO 2 being significantly faster at 21.25 minutes compared to VSDH and VSDHRh at 63.75 and 58.25, respectively, in P1. However, there were no significant differences in the TOD between VSDH or VSDHRh. There was also a significant increase in chamber ending CO 2 , for VSDCO 2 compared to VSDH and VSDHRh. However, both VSDH and VSDHRh broilers had significantly greater (P<0.0001) post core body temperatures indicating hyperthermia being the mode of action rather than hypoxia which is the mode of action in VSDCO 2 . The HSP70 levels were significantly greater in VSDH at 1.23 CT -1 compared to both VSDHRh at 0.98 CT -1 and VSDCO 2 at 0.90 CT -1 , which were not significantly different from each other. Blood chemistry parameters that were significantly higher in VSDCO 2 treatment broilers when compared to VSDHRh were total CO 2 (TCO 2 ), partial pressure of CO 2 (pCO 2 ), partial pressure of oxygen (pO 2 ), Bicarbonate (HCO 3), and blood oxygen saturation (sO 2 ). When compared to VSDH, TCO 2 , pCO 2 , and sO 2 levels were significantly greater in broilers undergoing the VSDCO 2 treatment. There were also no significant differences in corticosterone between treatments in P1 with corticosterone levels for VSDH being 0.11 ng/mL, 0.10 ng/mL for VSDHRh, and 0.12 ng/mL for VSDCO 2 . When analyzing the effects of these treatments on broilers over time in P2, there were no significant differences in corticosterone, blood chemistry, or HSP70 when compared within their respective treatments. Based on this research, VSDHRh may be an effective and useful depopulation method that may be used in the event of an outbreak. This is due to the equivalency of TOD in comparison to VSDH, with potential reduction in HSP70 levels. More research should be conducted on the effects of VSDHRh, especially in a non-environmentally controlled setting.

  PublisherDOI

• The effect of feed and water provision strategies on broiler breeder pullet performance and welfare

  Frontiers in Veterinary Science · 2025-08-08

  articleOpen access

  Feed restriction is common in the broiler breeder industry to optimize health and reproduction. However, this practice has been associated with increased drinking behavior, leading to water spillage, higher litter moisture, and footpad lesions. Consequently, parts of the industry have adopted water restriction protocols. This study aimed to evaluate how different combinations of feed and water restriction affected drinking behavior, welfare, and performance indicators in broiler breeder pullets. At 1 day of age, 960 Cobb 500 FF pullets ( Gallus gallus domesticus ) were randomly allocated to one of four treatments: skip-a-day feeding with ad libitum water (SAD + ADLIB), every-day feeding with ad libitum water (ED + ADLIB), skip-a-day feeding with 3 h daily water restriction (SAD + WR), and every-day feeding with 3 h daily water restriction (ED + WR). All data were analyzed with generalized linear or linear mixed effects models in R Studio. Drinking behavior was observed at 16 and 22 weeks at an hour after feeding (HAF), when water was turned off for SAD + WR and ED + WR (12:00), and when water access resumed for SAD + WR and ED + WR (14:30). The ED pullets displayed more drinker use at HAF at both ages ( p = 0.014), while SAD treatments performed more drinker use at 12:00 ( p &amp;lt; 0.0001) and 14:30 ( p = 0.0028) at 22 weeks. The WR pullets displayed more drinker use than ADLIB pullets at HAF and 14:30 ( p &amp;lt; 0.0001), while ADLIB pullets performed more drinker use at 12:00 ( p = 0.008). Water use (g/bird) was higher in ED + ADLIB pullets at 16 and 22 weeks compared to SAD+ADLIB pullets ( p = 0.042), but WR groups did not differ ( p &amp;gt; 0.05). Litter moisture under drinker lines reflected water use patterns, with ED pens wetter at 16 weeks ( p = 0.0011), but SAD pens unexpectedly had higher moisture at 22 weeks ( p = 0.011). General pen area litter was wetter in SAD and ADLIB groups ( p = 0.0036). Footpad scores did not differ among treatments ( p &amp;gt; 0.05). Body weight and uniformity did not drive water use. Overall, feeding program significantly influenced water use and behavior. Compensatory drinking in WR birds may indicate a welfare concern. Future research should explore measures of satiety and hydration to better understand the behavioral and physiological impacts of water restriction.

  PublisherOA PDFDOI

• Broiler Breeders Fed Diets Supplemented with Conventional or Lipid Matrix Microencapsulated Trace Minerals at Standard or High Levels: Part I. Influence on Production, Skeletal Integrity, and Intestinal Histomorphology of Broiler Breeders

  Poultry · 2025-04-06

  articleOpen access

  Lipid matrix microencapsulation is hypothesized to improve bioavailability for broiler breeders supplemented with normal and protect against excessive levels of inorganic trace minerals. At 27 weeks (wk), nine females and two males were assigned to each of the 12 floor pens. Each pen was randomly assigned to dietary treatments (trt) in a factorial arrangement of two mineral premix forms, free (FRTM) and microencapsulated (MITM), and two mineral premix supplement dosages (100% and 300% of Aviagen recommendations). At 55 wk termination, 15 hens/trt were randomly selected to assess tibia and jejunum morphology. Breeders receiving MITM improved hen day % (HD %), hen housed (HH%), and FCR but produced the lightest chicks at hatch. The TM form had no significant effect on histology, but TM 100% had greater villus height (VH), crypt depth (CD), and villi area than TM 300% (p &lt; 0.5). No significant treatment effects on bone weight, length, and bone mass density were observed. However, MITM treatments increased tibia thickness, and FRTM supplementation increased ash% and Cu content. Hens fed 300% TM had higher bone Mn content than 100% TM, whereas hens fed MI100 had the highest Fe content. Feeding lipid matrix microencapsulated trace minerals to broiler breeders does have positive impacts on the production of eggs, but no effects were observed in the histomorphology of the jejunum or tibia bone parameters.

  PublisherOA PDFDOI

• Assessment of the Effects of Stocking Density on Laying Hens Raised in Colony Cages: Part I—The Effect of Density, Time of Day and Hen Age on Behavior and Aggression

  Poultry · 2025-06-20

  articleOpen accessSenior author

  The amount of space provided to laying hens has been an animal welfare topic of concern from consumers, special interest groups, and lawmakers. The freedom to perform normal behaviors is one component of animal welfare, and, therefore, the objective of this study was to assess behavior at different stocking densities. Shaver White laying hens were housed in colony cages at five stocking densities. Video recordings of three cages/treatment were taken at 30, 46, and 62 weeks of age in the morning, afternoon, and night. At each age, a 20 min segment of video from each time of day was analyzed. Every minute was annotated to identify the behavior that hens spent the majority of their time performing. Data were averaged to calculate the percentage of hens engaged in each behavior per cage. The total count of aggressive bouts was recorded across the 20 min period. Data were analyzed with a general linear model utilizing the variables time of day, density, age, and the full factorial of interactions. Intermediate stocking densities displayed the lowest percentage of crouching (p = 0.009) and aggressive acts per hen (p &lt; 0.0001). Hens stocked at 1341.93 cm2 walked the most (p &lt; 0.0001). Hens were seen standing and preening (p &lt; 0.0001) more in the morning, crouching and sham dust bathing (p &lt; 0.0001) more in the afternoon, stretching less while feeding and drinking, and being more aggressive at night (p &lt; 0.0001). Finally, as hens aged, they began to stand and crouch more (p &lt; 0.0001) and preen (p = 0.013), walk (p &lt; 0.0001), and demonstrate aggressive behaviors (p = 0.007) less. In conclusion, the majority of behaviors assessed were not influenced by stocking density. However, the different amounts of aggression between the treatments could indicate higher stress and frustration, which warrants more investigation.

  PublisherDOI

• 34 Use of recycled ash from swine waste as a potential alternative dietary phosphorus source for pigs

  Journal of Animal Science · 2025-05-01

  articleOpen access

  Abstract Excess phosphorus excretion in manure can have negative environmental consequences, but could be recycled into the diet as a valuable dietary nutrient. Therefore, this study evaluated the potential of feeding recycled ash from swine lagoon sludge as an alternative phosphorus (P) source for swine. Fifty-six individually housed pigs (BW of 44.14±4.11 kg) were blocked by sex and initial BW and randomly assigned within blocks to 7 dietary treatments (8 blocks/treatment). Treatments consisted of a negative control diet (NC; 0.45% Ca and 0.12% available P representing 40% of the requirement), and the NC supplemented with either monosodium phosphate (MSP) or ashed swine lagoon sludge (ASLS) to provide an additional 0.05%, 0.10%, and 0.15% of total P, while maintaining a constant Ca:P ratio. Ash was produced through combustion reaching a peak temperature of 1800°C. Analyzed concentrations of Ca and P in ASLS were 8.42% and 9.31%, respectively. Diets were formulated using MSP, ASLS, limestone, salt, and fine sand while keeping other ingredients equal. Pigs were limit-fed at 3 times maintenance, calculated as 197 kcal ME/kg BW0.60 based on average BW for each block. Feed was provided twice daily for the 35-d study. Diet analysis showed that the NC diet exceeded targeted Ca and P concentrations and this diet was excluded from statistical analysis. Thus, data were analyzed as a 2×3 factorial arrangement with source (MSP or ASLS) and level (0.05, 0.10, and 0.15%) as factors. Final BW and overall average daily gain were not affected by treatments (P &amp;gt;0.27). Serum P concentrations linearly increased (P=0.022) in pigs supplemented with MSP (8.13, 8.53, 8.90 mg/dL) and tended to increase with ASLS supplementation (P=0.098; 8.26, 8.64, 8.79 mg/dL). Slope-ratio analysis for serum P indicated a bioavailability of P of 68.89% for ASLS. Analyzed P concentrations (DM basis) in feces increased linearly with the addition of P from MSP (P&amp;lt; 0.001; 1.79, 1.96, and 1.99%) and ASLS (P=0.014, 1.78, 1.85, 2.00 %) but there was no difference between sources (P=0.809). Apparent total tract digestibility of P increased (P&amp;lt; 0.001) with added P for both MSP (39.30, 48.23, and 48.56%) and ASLS (40.67, 46.39, and 48.17%) with no difference between sources (P=0.722). Third metacarpal bone breaking force increased linearly with increasing P from MSP (P&amp;lt; 0.001; 75.06, 99.90, and 114.89 kg) but not from ASLS (P=0.695; 98.11, 96.86, and 102.11 kg). Dry matter of the third metacarpal bone was not affected by treatment, but bone ash linearly increased (P=0.012) with additional P from ASLS (47.07, 48.20 and 48.70%), but not from MSP (P=0.135; 47.57, 48.03, and 48.52%). Results indicate that ASLS has reduced bioavailability compared to MSP as the standard, but can be used as an alternative dietary P source if approved as a feed ingredient.

  PublisherOA PDFDOI

• Broiler Breeders Fed Diets Supplemented with Conventional or Lipid Matrix Microencapsulated Trace Minerals at Standard or High Levels: Part II—Influence on Hatching Egg Quality

  Poultry · 2025-04-06

  articleOpen access

  The objective of this study was to evaluate the effects of free or microencapsulated trace mineral (TM) premixes at normal and high dietary inclusion levels on the internal and external quality and mineral composition of broiler breeder eggs. Twelve breeder pens were randomly assigned to one of four treatments consisting of a factorial arrangement of two TM premix forms (free and microencapsulated) and two dietary inclusion levels of TM premix (100% and 300% of Aviagen recommendations). Hens fed the microencapsulated TM had significantly greater vitelline membrane strength than those fed the free TM (1.92 g vs. 1.81 g, respectively (p &lt; 0.05)). Hens fed high dietary TM levels produced eggs with significantly greater shell elasticity and yolk color than hens fed the lower TM inclusion level (0.224 mm vs. 0.247 mm, and 8.89 vs. 8.62, respectively (p &lt; 0.05)). Only the whole-egg Mn concentration was observed to be significantly (p &lt; 0.01) increased by the higher dietary inclusion level of TM compared to lower (0.0301 mg/g vs. 0.0248 mg/g, respectively (p &lt; 0.01)). There were no treatment effects on eggshell mineral composition. Regardless of the dietary inclusion level, feeding broiler breeders microencapsulated TM does have some beneficial effects on the internal egg quality properties, whereas increased dietary TM supplementation levels improve the shell quality, yolk color index, and whole-egg Mn concentration. There were no significant premix form X TM premix dose effects observed.

  PublisherOA PDFDOI

• Assessment of the Effects of Stocking Density on Laying Hens Raised in Colony Cages: Part II—Egg Production, Egg Quality, and Welfare Parameters

  Poultry · 2025-06-20 · 2 citations

  articleOpen accessSenior author

  Stocking density is one of the major concerns in all production systems, which is why lawmakers, retailers, and consumers are increasingly concerned about this issue and its relation to animal welfare. The aim of this study was to identify if stocking density had an effect on white egg layer production, egg quality, bird health, and welfare parameters. For this study, five stocking densities were evaluated in colony cages: 1342 cm2/hen, 897 cm2/hen, 671 cm2/hen, 535 cm2/hen, and 445 cm2/hen. Egg production and physical egg quality were measured. Hen health and welfare parameters including corticosterone levels, H/L, oxidative stress pathways, jejunum tight junction protein expression, bone health, gut histology, body condition, and cytokine expression were evaluated. The results from this indicated that higher stocking densities resulted in lower production but larger eggs, while feed efficiency remained unaffected. Furthermore, physical egg quality parameters also remained unaffected. When stress and welfare parameters were analyzed, this research identified that decreasing stocking density did not affect jejunum oxidative stress pathways, pro-inflammatory cytokine expression, bone health, or intestinal health. At the final sampling period (69 weeks), the highest stocking density demonstrated higher corticosterone concentrations and IL-10 expression compared to the lowest stocking density. Furthermore, feather scores were found to be poorer as density increased. Finally, the highest density had higher Hansen’s test scores compared to other densities, which indicates a greater fear response. In conclusion, it appears that decreasing stocking density may provide some benefits in production and welfare to commercial egg layers, particularly at the end of the laying cycle.

  PublisherDOI

• Effects of an Unblanched Peanut and/or Peanut Skin Diet on Egg Quality, Egg Lipid Chemistry, and Performance of Hens Housed in a Cage-Free Environment

  Animals · 2025-09-12 · 1 citations

  articleOpen access

  Peanuts and poultry production predominate within the southeast US. Hence, the objective of this study was to determine the dietary effects of unblanched (skin-intact) high-oleic peanuts (HOPNs) and peanut skins (PN skins) on layer performance, egg quality, and fatty acid profile. To meet these objectives, 200 hens were randomly assigned to four treatments, housed in floor pens, and fed ad libitum for 8 weeks a control, HOPN (24%), PN Skin (3%), or 2.5% oleic acid (OA) diet. All empirical data was statistically analyzed for variance at the p &lt; 0.05 level. Hens fed the HOPN and PN Skin diets had heavier body weights relative to the controls at week 8 (p &lt; 0.05). Layers fed the HOPN treatment had poor FCR and smaller egg weights with lower levels of polyunsaturated fatty acids relative to the controls (p &lt; 0.05). Hens fed the PN Skin treatment had similar performance parameters, egg quality, and egg chemistry relative to the controls over the 8-week study. These results imply that PN skins may be an acceptable poultry feed additive without adverse effects on performance, egg quality, or egg lipid chemistry. Also, these results demonstrate the potential value-added utilization of PN skins, a waste by-product of the peanut industry, as a layer feed ingredient.

  PublisherOA PDFDOI

Frequent coauthors

• Ondulla T. Toomer

  Agricultural Research Service

  40 shared

• Vera Maria Barbosa de Moraes

  North Carolina State University

  27 shared

• Kenneth E. Anderson

  North Carolina State University

  25 shared

• Thien Vu

  Agricultural Research Service

  24 shared

• Rebecca Wysocky

  North Carolina State University

  22 shared

• Kari L Harding

  North Carolina State University

  17 shared

• P.R. Ferket

  North Carolina State University

  17 shared

• Johan Buyse

  15 shared

Labs

• Prestage Department of Poultry SciencePI