Grazing muzzles are used on obese-prone equids to limit intake of pasture while grazing. However, the length of time grazing muzzles must be worn to prevent weight gain and whether they impede normal grazing behavior to the degree they impact welfare is unknown. The objective of this study was to assess the effects of muzzling for different lengths of time on horse behavior and physiological stress. Six mature miniature horses (initial BW of 230 +/- 19.6 kg; BCS 6 +/- 0.4) were studied using a 3 x 3 Latin Square repeated measure design with horses receiving one of three treatments over three 21 d periods. Treatments were unmuzzled (MO), muzzled for 10 h (M10, 0830-1830 h), or muzzled for 24 h (M24). Horses were housed in adjacent individual 0.11 ha grass paddocks for 24 h/d. Daily at 0800 h, muzzles were removed, horses were groomed and fed 14 g vitamin and mineral supplement. Muzzles were re-applied at 0830 h. Body morphometrics were assessed at the start and end of each period. Each horse's willingness to accept muzzle application was measured daily using a 1 (strongly accepts) to 5 (strongly rejects) scale. Horse behavior was monitored twice weekly with video recordings for 1 h each in the morning and afternoon. Physiological stress was assessed weekly using salivary cortisol concentrations (SC), heart rate (HR), and indices of heart rate variability (HRV). Data were analyzed as repeated measures with treatment and wk as main effects. M24 horses lost BW while MO and M10 horses gained BW over the course of the study (P = 0.01). M24 horses spent more time grazing than M10 horses (P = 0.04). MO horses spent more time walking than M10 or M24 horses (P = 0.02). M10 horses spent more time resting than MO or M24 horses (P < 0.01), and a trend was observed where M10 horses spent more time lying down than M24 horses (P = 0.06). There was no effect of treatment on behaviors associated with frustration including pawing and head shaking. There was no effect of treatment on muzzle acceptability score; however, all horses were less accepting of muzzle application by the third wk of each period (P = 0.01). HR was lower and beat-to-beat interval was higher in M24 horses than in MO horses (P = 0.02, 0.04 respectively). Salivary cortisol concentrations were not different between treatments. Muzzling horses while on pasture for 24 hs a day resulted in a small loss of BW and altered time spent performing behaviors, but no observed impact on our physiological stress measures.

Grazing muzzles are a popular and effective management tool used to help prevent weight gain in obese-prone equids. Concerns have been raised over their possible negative impact on horse well-being as muzzles may interfere with normal grazing and social behaviors. The objective of this study was to assess the effects of grazing muzzles used for different lengths of time on behavior, voluntary exercise, and physiological stress of grazing horses housed in a herd. Six mature miniature horses (initial BW of 114.9 +/- 11.4 kg; BCS of 6.0 +/- 0.8) were studied using a 3 x 3 Latin Square repeated measure design with horses receiving one of three treatments daily for a period of 3 weeks. Treatments were unmuzzled (M0), muzzled for 10 h/d (M10, 0830-1830 h), or muzzled for nearly 24 h/d (M24). Horses were housed as a herd on a 0.6 ha grass pasture. Body weight (BW) was assessed weekly. Reaction to muzzle application was scored daily. Behavior was monitored with video twice weekly for two hours a day. An aggressiveness rank was assigned to each horse each period. Physiological stress was assessed weekly using changes in heart rate (HR), indices of heart rate variability, and salivary cortisol concentrations (SC). Voluntary exercise was measured for 24 h twice during each period. Data were analyzed as repeated measures with treatment and wk as main effects. Horses muzzled for 24 h/d lost BW while horses muzzled 0 or 10 h/d gained BW (P = 0.01). Horses muzzled for 24 h/d spent more time grazing (P = 0.04) and less time resting (P = 0.03) than M10 horses. Unmuzzled horses spent more time walking than M24 horses (P < 0.01), more time cantering than M10 (P = 0.02), and more time trotting than M10 and M24 (P = 0.04 and 0.01 respectively). Both muzzled treatments spent less time autogrooming with their mouths than unmuzzled horses (P < 0.01). Horses muzzled for 24 h/d had lower HR than M0 horses (P = 0.01) and higher beat-to-beat intervals than M0 and M10 horses (P = 0.01 and 0.03 respectively) while grazing. There were no effects of treatment on muzzle acceptability score, salivary cortisol, voluntary exercise, or change in aggressiveness rank. In conclusion, muzzling for 24 h/d prevented weight gain and did not cause apparent physiological stress. The lower HR and higher beat-to-beat interval in horses muzzled 24 h may be a potential health benefit and needs further exploration.

Recently, the Food and Drug Administration and Association of American Feed Control Officials approved Black Soldier Fly (BSF) larvae as a feed ingredient for poultry. The objectives of this work were 1) to formulate nutritionally balanced hen diets with BSF larvae meal and BSF larvae replacing corn and soybean meal, and 2) measure the impact of the dietary BSF treatments on hen performance and egg quality. In two experiments, BSF larvae meal (Exp 1, larvae with oil expressed) and BSF larvae (Exp 2, whole larvae) were fed to White Leghorn hens from 51 to 55 and 60-64 wks of age, respectively. The 216 hens were divided into 4 groups of 54 hens with one control group and 3 treatment groups. The hens were fed iso-caloric, isonitrogenous diets that had 3 dietary treatment levels of BSF larvae meal (8, 16 and 24%) and 3 levels of the larvae (6, 12 and 18%). Data were analyzed by one-factor ANOVA with the GLM procedure of SAS software (SAS, 2012) for the main effect of diet. Tukey’s multiple comparison was used for mean separation when the F-test was significant (P<0.05). Results obtained from Exp 1 found a negative impact when hens were fed BSF larvae meal at levels greater than 16%. Hens fed a diet devoid of soybean meal and completely replaced with meal had reduced feed consumption and egg production (P<0.05). Percent egg production averaged 85.14% for the control, 8 and 16% meal fed treatments and was significantly greater than hens were fed 24% meal at 77.01%. However, intermediate dietary meal levels (8 and 16%) had no negative impact on performance parameters and were not significantly different than hens fed the control diet. Yolk color was also significantly higher among the larvae meal treatments compared to the control. In Exp 2 hen body weight averaged 1737g, egg production 85.02% and egg size 64.17g and were not significantly impacted by the BSF larvae diets compared to the control (P > 0.05). However, feed intake and feed conversion (kg egg/kg feed) were significantly reduced by greater dietary levels of larvae (P < 0.05). Measures of egg quality including blood spots, meat spots and yolk color were not impacted by the treatment diets (P > 0.05), although egg specific gravity was higher (x̅=1.075 vs. 1.073) and albumen height (x̅=7.99 vs. 8.55) and Haugh units (x̅=87.54 vs. 91.28) were lower among the treatment eggs compared to the controls (P < 0.05). Egg yolk fatty acid profile was also impacted by the BSF larvae dietary treatments. Greater amounts of yolk fatty acids C12:0, C14:0, C14:1n5 and C21:0 were realized with increasing dietary levels of larvae (P < 0.05), however, there was no impact of the treatments on C18:2, linoleic acid or C18:3n3, alpha-linolenic acid (P > 0.05). It appears from these experiments that both BSF larvae and meal can be used as dietary sources of energy, protein, and amino acids for hen maintenance and egg production although there may be upper dietary limits. Furthermore, egg yolk fatty acid profiles can be impacted based upon the dietary levels of BSF larvae in the diet to reflect a more desired fatty acid profile at the manufacturer’s discretion. EFFECTS OF BUTYRATE ON NITROGEN CORRECTED APPARENT METABOLIZABLE ENERGY OF BROILER CHICKS Becky Y. Tran*, Michael Persia Virginia Tech Department of Animal and Poultry Sciences 175 West Campus Drive, Blacksburg, VA 24061 *Email: beckyt3@vt.edu ABSTRACT: In recent years, there has been pressure to find alternatives that can either replace or reduce the use of antibiotics in the poultry industry. As the intestines are the largest organ of the body, intestinal health has a tremendous effect on overall performance and nutrient utilization. Butyrate is a short-chain fatty acid that has the potential to promote the growth and proliferation of intestinal cells as a method to improve performance in the absence of feed antibiotics. The supplementation of a protected butyrate (designed to delay absorption of butyrate until it reaches the intestine) to growing broiler chicks should increase the intestinal health of broiler chickens resulting in an increase in nitrogen corrected Apparent Metabolizable Energy (AMEn). A control and protected butyrate diet were formulated and fed to six cages of 8 Cobb 500 broiler chicks for each treatment in this preliminary experiment. Chicks were provided ad libitum access to experimental diets and water. The chicks were wing banded and weighed individually at day 0, 16. Feed offered and refused was measured over the 16 day experimental period. On experiment day 14, the excreta pan below each cage were cleaned of excreta and clean paper was added. Excreta samples were taken from excreta collected from 14 to 16 days. Excreta samples were dried and analyzed for gross energy, nitrogen and titanium. Although there were no significant differences in body weight gain (P = 0.46) and mortality corrected feed conversion ratio (P = 0.70) between treatments, this was not unexpected as no challenge was provided to the birds and growing conditions were sanitary. However, the AMEn tended to be increased by 105 kcal/kg when butyrate was added to the diet in comparison to the control fed broilers (P = 0.10). This positive AMEn response could be due to increased intestinal health resulting in the increased nutrient absorption. Although not a direct replacement of antibiotics, it appears that butyrate can be used to potentially promote intestinal health resulting in increased nutrient absorption of broiler chickens. In recent years, there has been pressure to find alternatives that can either replace or reduce the use of antibiotics in the poultry industry. As the intestines are the largest organ of the body, intestinal health has a tremendous effect on overall performance and nutrient utilization. Butyrate is a short-chain fatty acid that has the potential to promote the growth and proliferation of intestinal cells as a method to improve performance in the absence of feed antibiotics. The supplementation of a protected butyrate (designed to delay absorption of butyrate until it reaches the intestine) to growing broiler chicks should increase the intestinal health of broiler chickens resulting in an increase in nitrogen corrected Apparent Metabolizable Energy (AMEn). A control and protected butyrate diet were formulated and fed to six cages of 8 Cobb 500 broiler chicks for each treatment in this preliminary experiment. Chicks were provided ad libitum access to experimental diets and water. The chicks were wing banded and weighed individually at day 0, 16. Feed offered and refused was measured over the 16 day experimental period. On experiment day 14, the excreta pan below each cage were cleaned of excreta and clean paper was added. Excreta samples were taken from excreta collected from 14 to 16 days. Excreta samples were dried and analyzed for gross energy, nitrogen and titanium. Although there were no significant differences in body weight gain (P = 0.46) and mortality corrected feed conversion ratio (P = 0.70) between treatments, this was not unexpected as no challenge was provided to the birds and growing conditions were sanitary. However, the AMEn tended to be increased by 105 kcal/kg when butyrate was added to the diet in comparison to the control fed broilers (P = 0.10). This positive AMEn response could be due to increased intestinal health resulting in the increased nutrient absorption. Although not a direct replacement of antibiotics, it appears that butyrate can be used to potentially promote intestinal health resulting in increased nutrient absorption of broiler chickens. THE IMPACT OF AGARICUS BLAZEI MUSHROOM EXTRACT WATER SUPPLEMENT ON HEN PERFORMANCE AND EGG QUALITY Trimble, L. D.*, A. D. Ferguson, N. Acar, P. H. Patterson The Pennsylvania State University College of Agricultural, Department of Animal Science 324 Henning Building, University Park, PA 16802 *Email: ldt5107@psu.edu ABSTRACT: An extract of the mushroom Agaricus blazei (ABE) was provided to commercial laying hens as the water supplement Agaricus Bio-CX manufactured by Atlas World USA, Inc. Pasadena, CA. Three levels of supplementation corresponding to 0.5, 1.0 and 3.0 times the manufacturer’s recommendations were provided to 10 replicate cages of hens per treatment and compared to Control birds receiving pure water during a 3 period (28 days/period) study. Body weight, feed intake, water intake, egg production and egg quality including egg weight, albumen height, Haugh units, specific gravity, blood spots, meat spots and yolk color were measured each period. Data were analyzed by one-factor ANOVA with the GLM procedure of SAS software (SAS, 2012) for the main effect of diet. Tukey’s multiple comparison was used for mean separation when the F-test was significant (P<0.05). The results indicated that the ABE had no significant impact on body weight or feed consumption during the 3-period study (P > 0.05). Egg production averaged 78.87% in period 1, 77.17% in period 2 and 74.08% in period 3, however, there were no significant differences due to the ABE treatments (P > 0.05). Feed conversion was not impacted by the ABE supplement in any time during the 3 periods (P > 0.05). Water consumption averaged 159.5 g/bird/day in period 1, 164.0 in period 2 and 164.5 in period 3, however, there were no significant treatment differences (P > 0.05). Neither was the water to feed intake ratio affected by the ABE treatments (P > 0.05). For egg quality no significant treatment effects on specific gravity, egg weight, blood or meat spots were observed (P > 0.05). In period 3, egg yolk color was significantly affected, but resulted in no biological significance with the levels of inclusion of ABE in the water (P > 0.05). In period 2, there was a linear impact of ABE on albumen height (P= 0.0057) and Haugh units (P =0.0126) suggesting lower quality with great inclusion of the ABE. Finally, no mortality was observed in the 3-period study (P > 0.05). These results sugg

Cigarette smoke exposure is a major cause of chronic obstructive pulmonary disease. Cadmium is a leading toxic component of cigarette smoke. Cadmium and zinc are highly related metals. Whereas, zinc is an essential metal required for normal health, cadmium is highly toxic. Zrt- and Irt-like protein 8 (ZIP8) is an avid transporter of both zinc and cadmium into cells and is abundantly expressed in the lung of smokers compared to nonsmokers. Our objective was to determine whether disturbed zinc homeostasis through diet or the zinc transporter ZIP8 increase susceptibility to lung damage following prolonged cigarette smoke exposure.Cigarette smoke exposure was evaluated in the lungs of mice subject to insufficient and sufficient zinc intakes, in transgenic ZIP8 overexpressing mice, and a novel myeloid-specific ZIP8 knockout strain.Moderate depletion of zinc intakes in adult mice resulted in a significant increase in lung cadmium burden and permanent lung tissue loss following prolonged smoke exposure. Overexpression of ZIP8 resulted in increased lung cadmium burden and more extensive lung damage, whereas cigarette smoke exposure in ZIP8 knockout mice resulted in increased lung tissue loss without a change in lung cadmium content, but a decrease in zinc.Overall, findings were consistent with past human studies. Imbalance in Zn homeostasis increases susceptibility to permanent lung injury following prolonged cigarette smoke exposure. Based on animal studies, both increased and decreased ZIP8 expression enhanced irreversible tissue damage in response to prolonged tobacco smoke exposure. We believe these findings represent an important advancement in our understanding of how imbalance in zinc homeostasis and cadmium exposure via tobacco smoke may increase susceptibility to smoking-induced lung disease.

Poultry breeding flocks experience stress from numerous sources including feed restrictions, confinement, social aggression, changing environments, transport, and stockperson turnover. Maternal diet and stress can increase catecholamine levels, including norepinephrine (NEP), and alter tyrosine metabolism. Elevated NEP levels impact the embryo and lead to altered survival behaviors in the developed offspring. In order to determine the effects of NEP on feeding and social behaviors, activity level, and fear response, Japanese quail (Coturnix japonica) embryos were injected with 10 μL of 0.01 or 0.05 M of NEP or saline at ED1 (n = 130) and incubated with intact controls (n = 80). Weekly behavioral scan samples (AM and PM) were taken from wk 4 (juvenile) to 11 (sexually mature) with rehoming between wk 6 and 7 samplings. Body weights were taken every other week, and organ weights were taken at wk 11. Tonic immobility tests were conducted at 2, 5, and 9 wk. Results showed a greater incidence of eating behavior in birds that received 0.01 or 0.05 M of NEP compared with control birds, with eating frequency increasing over time in older NEP-treated birds (P = 0.019, wk 5; P = 0.005, wk 10; and P = 0.017, wk 11). Younger birds that received 0.01 M of NEP spent more time drinking compared with birds that received 0.05 M of NEP or controls (P = 0.013, wk 5, and P = 0.016, wk 6). Birds that received 0.05 M of NEP foraged more frequently compared with birds that received 0.01 M of NEP (P = 0.002, wk 6; P = 0.046, wk 8; P = 0.002, wk 10; and P = 0.009, wk 11). Following rehoming, NEP-treated birds exhibited an increase in inactivity compared with control birds (P = 0.007, wk 7). Birds that received 0.01 M of NEP weighed significantly less than birds that received saline (P = 0.008, wk 3; P = 0.010, wk 5; P = 0.006, wk 7; and P = 0.006, wk 9). Relative heart, liver, and spleen weights did not significantly differ (P = 0.412, P = 0.561, and P = 0.293, respectively). We observed no difference in tonic immobility inductions (P = 0.637, wk 2; P = 0.475, wk 5; and P = 0.349, wk 9) or duration (P = 0.108, wk 2; P = 0.426, wk 5; and P = 0.730, wk 9). Our data show that NEP injections during early embryonic development have lasting impacts on feeding and drinking behaviors, activity levels, and weight. These results suggest that maternal and environmental stress, including rehoming, impact both production and behavior with implications for poultry management.

Sow lameness accounts for approximately 15% of culling, resulting in a decrease in productivity and welfare. Previous research in our laboratory has shown a high incidence of osteochondritic lesions in young sows. We hypothesized that decreasing the growth rate of sows would allow for proper formation of articular cartilage. The objectives of this study were to (1) quantify behavioral changes associated with the diet, and (2) prevent the development of osteochondritic lesions. Therefore, 70-d old gilts were placed on either a control diet (CON; n = 23) or a low energy diet (LOW; n = 24). The CON diet contained 3427 Kcal/kg ME. The LOW diet utilized wheat middling and soy hulls, and contained 2643 Kcal/kg ME, targeting 65 to 70% of growth. Both diets were available ad libitum from d 70 to 182. Gilts were fed LOW or CON diets in four 28 d phases, and were weighed at diet changes to calculate ADG and ADFI, which were 0.80 and 0.92 kg, respectively, for CON gilts and 0.61 and 1.06 kg, respectively, for LOW gilts. A G:F of 1.15 resulted for CON and 1.73 for LOW gilts. Behavioral observations were recorded monthly and included posture, activity, agonistic behavior, and vices. Joint samples were taken (CON = 9; LOW = 10) between d 182 to 361 and analyzed for damage. Joints were evaluated for number of lesions, lesion size, and received an articular cartilage score from 0 to 4, with 0 representing healthy cartilage and 4 representing severely lesioned cartilage. The LOW gilts spent more time standing (P < 0.01), sitting (P < 0.01), and feeding (P < 0.01). Overall, diet did not alter sham chewing (P = 0.76), nosing (P = 0.11), or tail biting (P = 0.36). Both LOW and CON gilts did not differ in the number of fights (P = 0.67); however, CON gilts spent less time fighting than LOW gilts (P < 0.01). Energy restricted feed did not decrease the lesion size or prevalence of lesions (P > 0.10). Older gilts had larger lesions on the proximal humerus (P < 0.01) and femur (P < 0.01) and the distal humerus (P < 0.03) and femur (P < 0.04) than younger gilts. An energy restricted diet is not a suitable solution to decrease fighting or to improve joint health in young sows.

Norepinephrine and epinephrine (noradrenaline and adrenaline) are integral in maintaining behavioral and physiological homeostasis during both aversive and rewarding events. They regulate the response to stressful stimuli through direct activation of adrenergic receptors in the central and sympathetic nervous systems, hormonal activity and through the interaction of the brain, gut, and microbiome. The multiple functions of these catecholamines work synergistically to prepare an individual for a “fight or flight” response. However, hyper-reactivity of this system can lead to increased fearfulness and aggression, decreased health and productivity, and a reduction in overall well-being. Behaviors, such as aggression and certain fear-related behaviors, are a serious problem in the poultry industry that can lead to injury and cannibalism. For decades, catecholamines have been used as a measure of stress in animals. However, few studies have specifically targeted the adrenergic systems as means to reduce behaviors that are damaging or maladapted to their rearing environments and improve animal well-being. This article attempts to address our current understanding of specific, adrenergic-regulated behaviors that impact chicken well-being and production.

Animal Production Science (continuing Australian Journal of Experimental Agriculture) publishes original research into applied agriculture including animal production, animal-plant interactions, pasture and fodder crops, field crops, extension and horticulture

The search for humane methods to euthanize piglets is critical to address public concern that current methods are not optimal. Blunt force trauma is considered humane but esthetically objectionable. Carbon dioxide (CO2) is used but criticized as aversive. This research sought to: 1) evaluate the aversiveness of inhaling nitrous oxide (N2O; 'laughing gas') using an approach-avoidance test relying on the piglet's perspective, and 2) validate its humaneness to induce loss of consciousness by electroencephalography (EEG). The gas mixtures tested were N2O and air (90%:10%; '90 N'); N2O, oxygen and air (60%:30%:10%; '60 N'); and CO2 and air (90%:10%; '90 C'). Experiment 1 allowed piglets to walk freely between one chamber filled with air and another prefilled with 60 N or 90 N. All piglets exposed to 60 N lasted for the 10 min test duration whereas all piglets exposed to 90 N had to be removed within 5 min because they fell recumbent and unresponsive and then started to flail. Experiment 2 performed the same test except the gas chamber held N2O prefilled at 25%, 50%, or 75% or CO2 prefilled at 7%, 14%, or 21%. The test was terminated more quickly at higher concentrations due to the piglets' responses. Time spent ataxic was greater in the middle concentration gradients. Flailing behavior tended to correlate with increasing concentrations of CO2 but not N2O. Experiment 3, using the minimal anesthesia model, showed that both 90 N and 90 C induced isoelectric EEG, in 71 and 59 s respectively, but not 60 N within 15 min. The EEG results together with the observed behavioral changes reflect differences in the animal's perceptive experience. The implications for animal welfare are that N2O is much less aversive than CO2, and 90% N2O can euthanize piglets.

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 infant mortality and failure to thrive (or unthriftiness), and umbilical 5-HT concentration in piglets. Umbilical blood was collected from a total of 60 piglets from 15 litters for analysis of 5-HT and tryptophan (Trp; the AA precursor to 5-HT) concentrations. Behavior was scan sampled for the first 2 days after birth. Brain samples were also taken at 8 h after birth from healthy and unthrifty piglets (n = 4/group). The raphe nucleus was dissected out and analyzed for 5-HT and dopamine concentrations as well as their major metabolites 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), respectively. Data were analyzed by ANOVA. Piglets that died within 48 h of birth (n = 14) had significantly lower umbilical blood 5-HT concentrations at the time of their birth compared to their healthy counterparts (n = 46, P = 0.003). However, no difference in Trp was detected (P 0.38). Time spent under the heat lamp and sleeping were positively correlated with umbilical 5-HT levels (P = 0.004 and P = 0.02, respectively), while inactivity had a negative correlation with 5-HT levels (P = 0.04). In the raphe nucleus, the center for brain 5-HT biosynthesis, unthrifty piglets had a greater concentration of 5-HIAA (P = 0.02) and a trend for higher concentrations of 5-HT (P = 0.07) compared with healthy piglets. Dopamine levels did not differ between thrifty and unthrifty piglets (P = 0.45); however, its metabolite HVA tended to be greater in unthrifty piglets (P = 0.05). Our results show evidence of serotonergic dysfunction, at both the central and peripheral levels, accompanying early piglet mortalities. These data suggest a possible route for intervention, via the 5-HT system, to improve piglet survivability. However, further research is required to validate this hypothesis.

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 in chickens.2. Our objective was to investigate the aggressive and impulsive behavioural response to antagonism of the 5-HT1A and 1B receptors in cocks bred for susceptibility and resistance to Marek's disease (i.e. strain 7(2) and 6(3), respectively).3. Cocks from strain 7(2) exhibited increased aggressive behaviours and lower brain 5-HT concentrations compared to strain 6(3) cocks.4. Antagonism of 5-HT1A receptors increased aggressiveness and reduced serotonin turnover in strain 7(2), but not strain 6(3) cocks. 5-HT1B receptor antagonism had no effect on aggression or serotonin turnover in either strain.5. Levels of the serotonin metabolite 5-HIAA, but not absolute central 5-HT levels, were altered in both strains following 5-HT1B antagonism, but only in strain 7(2) cocks following 5-HT1A antagonism.6. The data suggest that 5-HT1A and 1B regulate aggression differently in high and low aggressive strains.

Lighting can greatly alter broiler production and behavior. Currently, more energy-efficient means of illuminating broiler barns are being sought. Using LED light bulbs that are easily retrofit into existing electrical sockets are starting to become an alternative to incandescent bulbs. However, they still do not maximize the energy savings capacity of this technology as the bulbs must light the barn from the ceiling down. This project investigated using LED lighting attached to the feeders and waterers to light only the bird level. The treatments (n = 120 birds per treatment) were incandescent lighting (Incan), LED lighting (LEDhi) and LED lighting at bird level (LEDlo). All lighting was 23L:1D at 20 lx for 14 d and then was changed to 20L:4D at 5 lx for the remaining 31 d. Fearfulness was determined using several fear tests and stress susceptibility was assessed using a composite asymmetry score determined by middle toe length and metatarsal length and width. The Incan (2.73 ± 0.08 kg) birds weighed less (P < 0.05) after 45 d than both the LEDhi (2.95 ± 0.06 kg) and LEDlo birds (3.02 ± 0.05 kg). The LEDlo (1.61 ± 0.02) birds had better (P < 0.05) FCR than the Incan (1.71 ± 0.03) and LEDhi birds (1.67 ± 0.01). The LEDlo birds were less fearful (128.6 ± 9.15 s; 13.3 ± 2.1 s; P < 0.05) than the other birds in the emergence (Incan, 160.7 ± 6.7 s; LEDhi, 148.9 ± 7.4 s) and isolation tests (Incan, 27.7 ± 3.7 s; LEDhi, 23.2 ± 3.7 s). Both LED groups were less fearful (P = 0.05) during tonic immobility (LEDlo, 230.5 ± 27.6 s; LEDhi, 225.3 ± 25.9 s) and had lower composite asymmetry (LEDlo, 13.32 ± 0.15 mm; LEDhi, 1.68 ± 0.15 mm), when compared with the Incan birds (312.3 ± 26.6 s; 2.82 ± 0.19 mm). All data were analyzed using PROC GLM and significant differences were considered at P < 0.05; the LSD post hoc procedure was used for mean separation. The results indicate that illuminating the birds at their level not only increases growth and feed conversion but results in birds that are less fearful and less stress susceptible. This method of illuminating birds might save energy and improve production and bird welfare.

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-old White Leghorn hens were housed in 1 of 4 treatments with 9 hens per cage. Treatment 1 hens never had access to perches during their life cycle. Treatment 2 hens had access to perches during the pullet phase only. Treatment 3 hens had access to perches during the laying phase only. Treatment 4 hens always had access to perches. Liver weight, abdominal fat pad weight, BW, liver fat, and circulating alanine transaminase, aspartate transaminase, and adiponectin were determined. Provision of perches during either the rearing or laying phase did not affect liver health in 71-wk-old hens. However, perch access compared with no perch access during the egg laying phase reduced relative fat pad weight. These results suggest that providing perches as a means of stimulating activity reduced abdominal fat deposition in caged hens during the laying period. However, perch access in caged hens was ineffective in reducing fat deposition in the liver and altering enzyme activities related to improved liver function.

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 maternal effects from treatment. Eggs were injected with 50 μL of excess 5-HT (10 μg/egg), 8-OH-DPAT (a 5-HT1A receptor agonist; 16 μg/egg), or saline on day 0 prior to the 21 days incubation. Injections were performed at 0.5 cm below the shell. Behavior was analyzed at 9 weeks of age and again at the onset of sexual maturity (18 weeks). Hens treated with excess embryonic 5-HT exhibited significantly less aggressive behaviors at 9 weeks of age compared to both 5-HT1A agonist treated and saline hens (P < 0.05), and at 18 weeks of age compared to saline control birds only (P < 0.05). Excess embryonic 5-HT also increased fearfulness response (P < 0.05) as tested by duration of tonic immobility. Increased degree of fluctuating asymmetry at 18 weeks in 5-HT-treated birds (P < 0.05) suggests that excess 5-HT in early embryonic stages may create a developmental instability, causing phenotypic variations. These results showed that modification of the serotonergic system during early embryonic development alters its functions in mediating aggressive and fearful or anxious behaviors. Prenatal modification of the serotonergic system has long lived implications on both physiology and behavior, especially aggressive and fearful behaviors.

Serotonin (5-HT) acts as a neurogenic compound in the developing brain; however serotonin altering drugs such as SSRIs are often prescribed to pregnant and lactating mothers. Early agonism of 5-HT receptors could alter the development of serotonergic circuitry, altering neurotransmission and behaviors mediated by 5-HT signaling, including memory, fear and aggression. This study was designed to investigate the effects of early serotonin agonism on later behaviors. An extremely aggressive White leghorn strain (15I5) was used in the study. The chicks were injected with 5-MT (a serotonin agonist) at 2.5 mg/kg (low dose), 10 mg/kg (high dose) or saline (control) on the day of hatch and a second dose 24 h later (n = 9/sex/trt). Chicks’ fear response and memory were tested at 2 weeks of age. In the fear test, chicks were subjected to a social isolation test for 20 min, time to first vocalization and numbers of vocalizations were recorded. In the memory test, chicks were placed in a running wheel and presented with an imprinted object (white box with a red light) and a similar shaped novel object (blue box with a white light), respectively. The distance traveled in the wheel toward each object was measured. At 10 weeks of age birds were tested for aggression and concentrations of catecholamines were determined from the raphe nucleus and hypothalamus by HPLC (n = 12). Expression of 5-HT1A and 5-HT1B receptor genes were measured by RT-PCR. Both high and low dose chicks tended to have shorter latency to first vocalization and a greater number of vocalizations compared with control chicks. Memory test showed that chicks from all groups traveled a similar distance toward a familiar object. However, control chicks walked the least toward a novel object, low dose chicks tended to walk further, and high dose chicks walked significantly further for a novel object. In aggression tests, both high and low dose males exhibited greater frequency of aggressive behaviors compared to controls, while no difference in aggression was evident in the females. Norepinephrine concentrations were also reduced in the low dose birds in the hypothalamus and in the raphe nucleus. Serotonin concentrations tended to be lower only in the both hypothalamus and raphe nucleus of the low dose birds. 5-HT1A expression was greatest in the hypothalamus and raphe nucleus of low dose birds. The agonism of the serotonin system during neural development of birds genetically predisposed to aggression alters both the dopaminergic and serotonergic systems further increasing their aggressiveness.

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 production and KGB (kind, gentle bird), a strain selected for high group productivity and survivability. Ninety hens (48 DXL and 42 KGB) at 28 wk of age were randomly assigned to either a hot (H: mean = 32.6°C) or control (C: mean = 24.3°C) treatment and housed in pairs by strain for 9 d. Egg production and quality, behavior, body and organ weights, and circulating hormone concentrations were measured. Heat-stressed hens had lower egg production [adjusted (adj) P < 0.001] than their respective controls. Among H-DXL hens, egg weight tended to be reduced at d 1 and was reduced at d 9 (adj P = 0.007), but was reduced only at d 9 among H-KGB hens (adj P = 0.007). Eggshell thickness was also reduced among H hens at d 9 (adj P = 0.007), especially among H-KGB hens (adj P = 0.01). Plasma triiodothyronine concentration was reduced among H-hens (adj P = 0.01), especially among H-DXL hens (adj P = 0.01). Neither temperature nor strain affected the plasma thyroxine and plasma and yolk corticosterone concentrations. Heat-stressed hens spent less time walking (adj P = 0.001) and more time drinking (adj P = 0.007) and resting (adj P = 0.001) than C-hens. The results indicate that although HS reduced production and caused behavioral changes among hens from both strains, the responses differed by genotype. The data provide evidence that genetic selection is a useful strategy for reducing HS response in laying hens. The results provide insights for conducting future studies to develop heat-resistant strains to improve hen well-being, especially under the current commercial conditions.

Public concern about the welfare of hens kept in conventional cages has become an important issue worldwide. This study examined the effects of conventional cages (CC) and floor pens (FP) on hens’ health and egg production. A total of 84 19-wk-old Bovan Brown hens were randomly assigned into 2-bird cage (n = 12), providing 968 cm2 floor space per hen or 10-bird floor pens (n = 6), providing 3711 cm2 floor space per hen for 8 wks. The floor pens were furnished with perches, nest boxes, and wood shavings. Egg production was recorded up to 27 wk of age. Egg weight, egg quality and shell quality were measured at wk 23, 25, and 27. Plumage condition, foot health, mineral density of tibia, femur, humerus, and heterophil/lymphocyte (H/L) ratio were evaluated at wk 27. Daily egg production, plumage condition, and feet hyperkeratosis of hens were not affected by the housing environment (P > 0.05). The mean claw lengths of caged hens were longer (CC = 1.11 ± 0.02, FP = 0.87 ± 0.02, P < 0.0001) than those housed in floor pens. Compared with floor pen housed hens, caged hens had greater egg weight and larger width at 23 wk of age (CC = 62.65 ± 0.85, FP = 57.83 ± 0.85, P = 0.001 and CC = 44.28 ± 0.22, FP = 42.99 ± 0.27, P = 0.001, respectively). However, the floor pen housed hens had higher shell mass at 23 wk of age (CC = 0.09 ± 0.001, FP = 0.10 ± 0.001, P = 0.001). Floor pen housed hens also had greater bone mineral density in all 3 bones than that of the caged hens (P = 0.002). The H/L ratio, an immunological response parameter and stress indicator, was higher (CC = 3.76 ± 0.09, FP = 3.32 ± 0.09, P = 0.002) in caged hens. Overall, the results suggest that furnished floor pens may be a favorable alternative housing system to conventional cages for improving hen welfare; however, the cages still have certain advantages for egg production.