Performing Department
(N/A)
Non Technical Summary
In the United States, conventional raised broiler chickens dominates the poultry industry as it is a very efficient and safe method of poultry production. Despite the safe and economical poultry products that are produced by U.S. poultry companies, consumer demand for meat that is produced through alternative methods (pasture, free range, and organic) continues to increase. In 2019, sales of organic chicken were $1.115 billion, and the value of the U.S. broiler chicken industry in 2021 was about $31.5 billion. Studies evaluating early age thermal conditioning, diet manipulation on heat stressed pastured poultry are limited. The objectives of this project are to 1. Evaluate the performance effects, stress response parameters, and bird behavior indicators of early age thermal conditioning, and feeding tryptophan and pre and probiotic supplemented diets, to mitigate the effects of heat stress on different breeds of chickens raised on pasture; 2. Evaluate carcass microbial levels and fecal microbiome from different breeds of chickens raised on pasture fed tryptophan and pre and probiotic supplemented diets; and 3. Establish a pasture poultry extension program at University of Maryland Eastern Shore (UMES) to assist poultry growers in the region. The ultimate goal of this project is to establish a research foundation at UMES to develop research projects to address challenges surrounding pasture raised poultry, and educate high-skilled graduates who are needed in the region and nation. This projectmeets the follwing CBG priority areas: food safety, rural communities for the 21st century and sustainable agriculture.
Animal Health Component
15%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The goal of this projectis to evaluate early age thermal conditioning and nutritional strategies to improve the health and welfare of chickens raised on pasture. Theobjectives of this project are:i. Evaluate the performance effects, stress response parameters, and bird behavior indicators of early age thermal conditioning, and feeding tryptophan(Trp) and pre and probiotic supplemented diets, to mitigate the effects of acute heat stress on two breeds of chickens (fast growing commercial broilers (FGB) and crossbred slow-growing broiler breed, (SGB)raised on pasture. ii. Evaluate carcass microbial levels and fecal microbiome from two breeds of chickens (FGB and SGB) raised on pasture fed Trp and pre and probiotic supplemented diets.iii. Establish a pasture poultry extension program at UMES to assist poultry growers in the region.
Project Methods
Project Methods1) Study 1 (Trp and heat stress effect): This will be a randomized complete block (RCB) design as a 2x2 factorial arrangement of treatments with 4 treatments and 8 replicates per treatment. The birds will be fed diets with and without Trp supplementation and will be exposed to either an acute heat stress environment (41? temperature for 6 hours at 20 d of age and 35? for 6 hours at 41 d of age, or a control (thermo-neutral temperature regime (25.5? for 6 hours at 20 d of age and 19? for 6 hours at 41 d of age). At the end of the 42 d study, performance parameters will be measured. In addition, behavior indicatorswill be measured. Blood corticosterone levels, and bursa and spleen weights will be measured for stress response indicators. Also soil samples for nutrient analysis will be collected prior to placing birds on pasture and at the end of the trial to determine the impact of raising birds on pasture on the soil nutrient content.Treatments: 1) 0% added Trp diet and thermo-neutral temperature regime (25.5? for 6 hours at 20 d of age and 19? for 6 hours at 41 d of age), 2) 0% added Trp diet and acute heat stress regime (41? temperature for 6 hours at 20 d of age and 35? for 6 hours at 41 d of age), 3) 0.4% added Trp diet and thermo-neutral temperature regime (25.5? for 6 hours at 20 d of age and 19? for 6 hours at 41 d of age), and 4) 0.4% added Trp diet and acute heat stress regime (41? temperature for 6 hours at 20 d of age and 35? for 6 hours at 41 d of age).For the heat stress treatments (d 20 and 41), birds will be moved by pen to temperature controlled rooms. Room temperature and relative humidity will be monitored during the heat stress treatments. Recording cameras will be installed to measure behavior indicatorswill be measured during the heat stress treatments, and when birds are outside on pasture. At the end of the 6 hour heat stress period birds will be moved back to their respective pens on pasture. At the end of the trial (d 42), two birds per pen will be selected for processing. Blood will be collected from each bird to measure corticosterone levels immediately upon handling.Additionally bursa and spleen weights will be collected from each bird. Fecal samples for microbiome will be analyzed using 16S rRNA sequencing. Carcass samples will also be tested for the presence of Salmonella using the whole carcass enrichment methods.This trial will be conducted two times. The first trial will use FGB (Cornish x White Plymouth Rock cross) and the second trial will use SGB.2) Study 2 (thermal conditioning and heat stress effect): This will be a RCB design as a 2x2 factorial arrangement of treatments with 4 treatments and 8 replicates per treatment. The factors for this study include thermal conditioning (unexposed control group, 31? or chicks exposed to 36? and 70-80% relative humidity at 5 d of age for 24 hours x grow-out temperature (thermo-neutral control or heat stress). At hatch, 12 male broiler chickens (experimental unit) will be group weighed and brooded in pens inside the UMES research house. At 5 d of age, the thermal conditioned treatment (36? and 70-80% relative humidity for 24 hours) will be applied to chicks. All chickswill be moved to pensoutside on the UMES farm when they have obtained sufficient plumage (approximately 14 days of age). The birds will be exposed to either an acute heat stress environment (41? for 6 hours at 20 d of age and 35? for 6 hours at 41 d of age,) or a control (thermo-neutral temperature regime (25.5? for 6 hours at 20 d of age and 19? for 6 hours at 41 d of age). At the end of the 42 d study, performance parameters will be measured (body weight gain, feed efficiency, feed consumption, mortality, and carcass yield). In addition, behavior indicators such as number of birds observed panting, wing spreading, eating, and drinking during heat stress exposure period (20 and 41 d of age) will be measured. Blood corticosterone levels, and bursa and spleen weights will be measured for stress response indicators.Treatments: 1) Unexposed thermal conditioning and thermo-neutral temperature regime, 2) Unexposed thermal conditioning and acute heat stress regime, 3) Thermal conditioned and thermo-neutral temperature regime, and 4) Thermal conditioned and acute heat stress regime.For the heat stress treatments (d 20 and 41), birds will be moved by pen to temperature controlled rooms. Room temperature and relative humidity will be monitored during the heat stress treatments. Recording cameras will be installed to evaluate behavior indicators during the heat stress treatments, and when birds are outside on pasture. At the end of the 6 hour heat stress period birds will be moved back to their respective pens on pasture. At the end of the trial (d 42), two birds per pen will be selected for processing. Each bird will be wing tagged and a live weight will be recorded. Blood will be collected from each bird to measure corticosterone levels. UMES's SOP will be followed to humanely process the birds for carcass yield determination. Additionally bursa and spleen weights will be collected from each bird. Fecal samples for microbiome will be analyzed using 16S rRNA sequencing. Carcass samples will also be tested for the presence of Salmonella using the whole carcass enrichment methods.This trial will be conducted two times. The first trial will use FGB and the second trial will use SGB. Genotype selection will be the same as described in Study 1.3) Study 3 (probiotic/prebiotic and heat stress effect): Two flocks (Ross 708) will be raised during the summer in Mississippi (June-August) using a RCB design with a 2 X 4 factorial arrangement of treatments i.e. thermoneutral-control or heat stress and four dietary treatments consisting of. 1) corn/SBM diet (control diet), 2) the control diet plus probiotic , 3) control diet plus prebiotic , or 4) control diet with a combination of prebiotic and probiotic. Each treatment will be made up of 5 replicates with 15 birds/replicate.Thermal conditioned chicks will be exposed to 36? and 70-80% relative humidity at 5 d of age for 24 hours.After thermal conditioning and brooding period (d 15) chicks will be transferred to well-established pasture. Portable pens with open bottoms will be used to house the birds at a stocking density of 3 ft2 per bird. Pens will be moved once or twice a day depending on pasture conditions, diets and water will be offered ad libitum. Broiler performance will be evaluated weekly. Blood samples will be collected before and after heat stress and analyzed for pH, pO2, pCO2, HCO3, glucose, Na+, and K+ using a VetScan i-Stat analyzer and EC81 cartridges (Abaxis, Union City, CA) in addition, circulating levels of triiodothyronine (T3), thyroxine (T4), and corticosterone (CORT) in plasma will determined using commercial kits4) Study 4. Effects of dietary probiotic and prebiotic on broiler exposed to heat stress in commercial house setting.A similar experiment design as the one described in Study 3 will be used to conducted research using floor pens in a commercial broiler house. However, all birds (thermos-conditioned and non-conditioned birds) will be exposed to constant heat stress (32oC) for 6 hours per d for a duration of last two weeks before processing.Meat Quality parameters: After processing, chicken breast and thigh meat will be analyzed for lipid oxidation using 2 -thiobarbituric acid reactive substance (Min and Ahn, 2009). Protein oxidation and antioxidant capacity using oxygen radical absorbance capacity will also be determined (Lund et al., 2008; Min et al., 2017) respectively. Shear force and texture profile of cooked meat will be determined using a texture analyzer.