Effect of a Broiler-Specific Light Spectrum on Growth Performance and Adrenocortical Activity in Chickens: A Pilot Study on a Commercial Farm

This study evaluated the effect of a broiler-specific light spectrum on productive performance corticosterone (fCC) and androgen dehydroepiandrosterone (fDHEA) concentrations in feathers, and glucocorticoid (GCMs) and androgen (AMs) metabolites in droppings of broilers. Two groups of female Ross 308 broilers were reared under white LED (WL, n = 9000) and broiler-specific LED (BSL, n = 9000) lights. The body weight (BW) of 150 randomly selected animals/groups was measured weekly. Droppings and feathers were collected at the end of the cycle (29 days) from 20 animals/group. The BSL group showed higher final BW than WL (1407 ± 11 vs. 1341 ± 15 g, respectively; p < 0.001) and higher indices of uniformity (76.8% vs. 61.2% animals in the 10% around the mean, respectively; p < 0.001). No difference between groups was found in fCC and fDHEA concentrations or in the fCC-fDHEA, indicating similar long-term HPA axis activity during the cycle. A higher concentration of GCMs was found in the BSL group, indicating higher glucocorticoid secretion before sampling, with neither a difference in AMs nor in GCMs-AMs. Finally, there was a positive correlation between fCC and fDHEA and between GCMs and AMs (p < 0.01). Our findings suggest that the use of broiler-specific light improved the productivity performances of chickens without long-term consequences on HPA activation. However, the results of this pilot study in a commercial farm setting must be interpreted with caution and need confirmation.

The Effect of Environmental Enrichment on Selected Physiological and Immunological Stress-Related Markers in Dairy Goats

Homeostasis preservation is essential for animal survival, and any event that causes a disturbance in homeostasis is defined as a stressor. Here, we aimed to evaluate the effect of scratch brushes and stages as an environmental enrichment to alleviate stress in dairy goats. Twenty-four mixed-breed goats were divided into two groups according to common physiological conditions in breeding farms: milking and dry (milk-producing and non-milk-producing, respectively). Ten days after exposure to environmental enrichment treatment or not (control), blood was sampled. Following the enrichment, we observed a reduction in reactive oxidative stress metabolites, advanced glycation end products (AGEs), and their binding protein (transferrin) in the dry goats, as determined by an ELISA. In contrast, no change in AGEs, along with an increase in transferrin levels, was observed in the milking goats. Moreover, oxytocin levels decreased in the dry and increased in the milking goats, while serotonin levels increased in the dry and remained unchanged in the milking goats. Additionally, gene expression of the cytokines, IL-6 and IL-1ß, and anti-oxidative proteins, lysozyme and transferrin (in peripheral blood leukocytes), as determined by qPCR, presented the same pattern: down-regulation in the dry or up-regulation in the milking goats. In conclusion, a reliable methodology was developed for measuring husbandry stress in goats and to improve dairy goats' husbandry practice. Current environmental enrichment produced different responsiveness in goats correlated to their physiological status: beneficial effect in dry goats, detrimental effect in milking goats.

Biological validation of faecal corticosterone metabolites as a non-invasive stress assessment in translocated California valley quail (Callipepla californica)

US quail species are vulnerable to population declines as a result of climate change, habitat loss and habitat fragmentation, all of which can result in physiological stress. Additionally, population restoration techniques (PRTs), like translocations, also induce stress. Traditional assessments of avian stress hormone levels include capturing and handling birds to extract blood, methods that are inherently stressful and can compound stress analyses. However, the stress hormone corticosterone (CORT) is metabolized from the blood and excreted in faeces as faecal corticosterone metabolites (FCMs). FCMs have been used as a non-invasive measurement of stress hormone levels in a variety of species, but must be validated for each species. The objective of this study was to biologically validate the use of FCMs as a non-invasive measurement of CORT levels in California valley quail (Callipepla californica). Reference and treatment quail were acclimated for 3 weeks in an outdoor aviary. Subsequently, treatment quail were subjected to a simulated 48-h translocation, a common and stress hormone-inducing PRT. Faecal samples were collected every 4 h and processed using an enzyme immunoassay. Mean FCM concentrations of treatment quail (41.50 ± 16.13 ng/g) were higher than reference FCM concentrations (24.07 ± 10.4 ng/g). These results biologically validate the use of FCMs as a non-invasive method to assess CORT levels in California valley quail, demonstrate diurnal variation in quail CORT levels, and confirm that quail translocations are a stress-inducing PRT. Ultimately, this research validates a new non-invasive tool for stress response measurement to advance quail research, management and conservation.

Effect of larval handling on black soldier fly life history traits and bioconversion efficiency

Introduction

The black soldier fly is considered the most promising insect species for mass production; however, information on the effects of handling, which is unavoidable during experimental trials and rearing practices, is still limited.

Materials and methods

To address this gap, three different manipulation intensities were tested on 100 6-day-old larvae per replica (6 replicates/treatments) fed on Gainesville diet: (1) hard-handled (HH), larvae underwent continuous manipulation until the end of larval stage, (2) soft-handled (SH), larvae were manipulated after the appearance of the first prepupa, (3) no-handled (NH), larvae remained untouched. Every 4 days from the beginning to the end of the larval stage, the manipulations lasted 30 min and occurred under laboratory conditions (20°C). During the sampling operations, at least 30 larvae were randomly extracted, washed, dried, and weight-mimicked. At the end of larval stage, all the boxes remained untouched until the adult fly stage, and the emergency rate and sex ratio were evaluated on dead flies. Data were statistically analyzed using IBM SPSS V20.0.0 software and the considered significance level was p < 0.05.

Results

The larval stage lasted 8.2 days for both HH and SH (p > 0.05). Despite the HH larvae being the most manipulated, no difference was also observed in final weight (HH, 160 mg; SH, 150 mg; p > 0.05) and survival rate (HH, 96.2%; SH, 94.5%; p > 0.05). The manipulation did not influence the bioconversion capacity of the larvae (bioconversion efficiency corrected for the residue: HH, 14.3%; SH, 12.91%; reduction rate: HH, 58.4%; SH, 55.9%; waste reduction index: HH, 7.28%/day; SH, 7.25%/day; p > 0.05). Finally, the development time from larva to fly (about 20.7; p > 0.05), the emergency rate (NH: 92.8%; SH: 89.5%; HH: 82.7%) and sex ratio (~1.2% to male flies) were not affected by the handling (p > 0.05).

Discussion

In conclusion, the handling procedures used in the current study did not influence the life history traits of the black soldier fly. However, further studies are needed to evaluate if different experimental protocols on various scales, the colony strain or other handling procedures may suggest a different scenario or confirm the results.

Investigations of Histomonosis-Favouring Conditions: A Hypotheses-Generating Case-Series-Study

Since the ban of effective feed additives and therapeutics, histomonosis has become an important disease and, subsequently, a welfare issue for turkey production. We conducted an interview-based case series study to generate hypotheses about possible disease-favouring conditions in 31 H. meleagridis-infected flocks. The determined parameters were related to the general farm (flock management, biosecurity measures, etc.) as well as the histomonosis-specific disease management. Some inadequate biosecurity measures were observed. An inappropriate usage of the hygiene lock and cleaning as well as the disinfection frequency of equipment, clothes, and the hygiene lock could possibly be histomonosis-favouring conditions. These factors could increase the risk for the introduction of H. meleagridis and the risk of a pathogen spread on an affected farm. Insects, wild birds, litter materials, and contaminated dung could be potential vectors of H. meleagridis. Predisposing gastrointestinal diseases were observed in 71% of the affected flocks. Additionally, stress events related to higher temperature, movement of birds, and vaccination were documented in association with clinical histomonosis. The results emphasise the need for both good disease control and health management to ensure sustainable animal health and welfare.

Effects of anti-stress agents on the growth performance and immune function in broiler chickens with vaccination-induced stress

The aim of this study was to evaluate the effects of anti-stress agents on the growth performance and immune function of broilers under immune stress conditions induced by vaccination. A total of 128, 1-day-old Arbor Acres broilers were randomly divided into four groups. Group normal control (NC) was the control group. Group vaccination control (VC), T 0.5%, and T 1% were the treatment groups, which were nasally vaccinated with two doses of the Newcastle disease virus (NDV) vaccine. The chicks in groups T 0.5% and T 1% were fed conventional diets containing 0.5% and 1% anti-stress agents. Thereafter, these broilers were slaughtered on 1, 7, 14, and 21 days post-vaccination. The results indicated that anti-stress agents could significantly reduce serum adrenocorticotropic hormone (ACTH) (P < 0.01) and cortisol (CORT) (P < 0.05) levels, and improve the growth performance (P < 0.05) and immune function of broilers (P < 0.05); However, the levels of malondialdehyde (MDA) (P < 0.05) were decreased, and the decreased total antioxidant capacity (T-AOC) (P < 0.01) levels mediated by vaccination were markedly improved. In addition, anti-stress agents could attenuate apoptosis in spleen lymphocytes (P < 0.01) by upregulating the ratio of Bcl-2 to BAX (P < 0.01) and downregulating the expression of caspase-3 and -9 (P < 0.01), which might be attributed to the inhibition of the enzymatic activities of caspase-3 and -9 (P < 0.05). In conclusion, anti-stress agents may improve growth performance and immune function in broilers under immune-stress conditions.RESEARCH HIGHLIGHTS Investigation of effects and mechanism of immune stress induced by vaccination.Beneficial effect of anti-stress agents on growth performance, immune function, oxidative stress, and regulation of lymphocyte apoptosis.Demonstration of the effects of apoptosis on immune function in the organism.

Zeolite and corn with different compositions in broiler chickens feeding

The objective of this work was to evaluate the behavior of zeolite against different types of corn in broiler chickens' diets. 1,200 male broiler chickens were assigned to 6 diets in a completely randomized design and a 2 × 3 factorial arrangement, consisting of 2 types of corn (higher or lower mycotoxin contamination) and the inclusion of zeolite (0; 5,000 and 10,000 g ton^-1). In the period from d 1 to 21, there was an interaction (P = 0.0040) between types of corn and the inclusion of zeolite for feed conversion ratio (FCR). In the phase from 1 to 42 d, there was an interaction (P = 0.0322) on the serum levels of creatinine (CREA) and digestible gross energy (dGE); corn with lower mycotoxin level contamination (LMLC), caused a reduction in body weight gain (BWG) (P = 0.0046) and increase in the relative weight of abdominal fat (P = 0.0256). Inclusion rates of zeolite promoted an increase in the digestible CP (P = 0.0477) and digestible ash (P < 0.0001), as well as an increase (P < 0.0001) in hot carcass yield (P = 0.0433). The results indicate that the inclusion of zeolite, in the amounts used, did not alter the performance, serum levels, intestinal development and litter quality of the birds at 42 d of age. However, it was responsible for the improvement in the percentage of digestible nutrients (CP, GE, and MM).

Rubber (Hevea brasiliensis) seed oil supplementation attenuates immunological stress and inflammatory response in lipopolysaccharide-challenged laying hens

This study was conducted to investigate the effect of PUFA-enriched rubber (Hevea brasiliensis) seed oil (RSO) supplementation in diets on the productive performance, plasma biochemical parameters, immune response, and inflammation in lipopolysaccharide (LPS)-challenged laying hens. Two hundred and forty 25-wk-old Lohmann Brown laying hens were randomly divided into 5 treatments, each including 4 replicates with 12 birds per replicate. The control group and LPS-challenged group were fed a corn-soybean-basal diet; 3 RSO-supplemented groups were fed experimental diets containing 1, 2, and 4% RSO for a feeding period of 4 wk. On the 15, 18, 21, 24, and 27 d of the RSO supplementation period of 4 wk, hens were injected intraperitoneally with LPS at 1 mg/kg body weight (challenge group and RSO-supplemented groups) or with the same amount of saline (control group). The results showed that the addition of RSO promoted laying performance by increasing egg production, total egg weight, daily egg mass, and feed intake in comparison to the LPS-challenged laying hens (P < 0.05). In addition, compared with laying hens stimulated with LPS, the analysis of blood cell and plasma parameters revealed that hens in RSO-supplemented groups had significantly lower levels (P < 0.05) of white blood cells (WBC), lymphocytes (LYM), aspartate aminotransferase (AST) activity, immunoglobulin A (IgA), triiodothyronine (T3), interleukin-2 (IL-2), and tumor necrosis factor-α (TNF-α). Further, RSO supplementation significantly reduced the mRNA expression of toll-like receptor 4 (TLR4), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukin-6 (IL-6), and interleukin-1β (IL-1β) of the ileum, spleen, and liver in LPS-challenged laying hens (P < 0.05), suggesting that the anti-inflammatory mechanism of RSO is related to the TLR4/NF-κB signaling pathway. In conclusion, RSO supplementation in diets could improve laying performance, attenuate immunological stress, and inhibit the inflammatory response in LPS-challenged laying hens, especially at the dietary inclusion of 4% RSO. This study will provide an insight into the application of RSO to positively contribute to overall health and welfare in laying hens.

The Benefit of Hedgerow Access on the Health and Growth Rate of Pasture Raised Broiler Chickens

Pasture rearing is an increasingly common option for small farms to produce humanely raised poultry products for an expanding market, however profit margins tend to be much lower for pastured poultry producers than for those that opt for conventional indoor rearing. Research into simple methods to optimize the growth and health of pasture-raised poultry can help small farmers maximize meat yields and decrease the morbidity and mortality of their flock, ultimately leading to higher profit margins and improved animal welfare. The objective of this study was to measure how the inclusion of mature, native foliage into pastures can impact the production performance and overall health status of two different popular breeds of commercial broiler chickens; fast-growing Cornish cross and slower growing Red rangers. During the finisher phase (30–78 days old), pastured chickens were separated by breed into either a treatment population with access to a mature bordering hedgerow, or a control population without access to a hedgerow. Weekly weight gain, daily feed intake and basic hematologic values were used to evaluate differences in the production performance and health status between each population. We found that hedge access led to a significant improvement in the rate of gain of the Cornish cross without an associated increase in feed intake, suggesting that the addition of hedges can increase meat yields in fast-growing broilers without increasing feed costs. Red rangers with hedge access demonstrated an improved ability to neutralize bacterial pathogens in whole blood and a lesser degree of hemodilution compared to control populations, suggesting improved immune function and a lower degree of heat stress in these populations. We conclude that the addition of natural environmental enrichment such as mature foliage to grass pastures can lead to improved production performance in fast-growing broilers and improvements in the health and immune function of slower growing broiler chickens.

Research Note: A sip of stress. Effects of corticosterone supplementation in drinking water on feather corticosterone concentrations in layer pullets

The measurement of feather corticosterone concentrations (fCORT) is a comparatively new method for the evaluation of stress in wild and captive birds and may be a useful indicator in animal welfare research. The aim of this study was to assess the suitability of fCORT as an indicator of stress, and for this purpose a prolonged stress period was experimentally simulated by oral intake of corticosterone via drinking water and corticosterone concentrations were analyzed in feathers grown during this period. Layer pullets of both a control group (n = 20) and a CORT group (n = 20) were offered drinking water ad libitum throughout the entire experimental phase. The drinking water of the CORT group was supplemented with corticosterone at a concentration of 20 mg/l from the 64th to the 114th day of life. The vaned parts of the primaries 5 (P5s) were clipped on d 114 and fCORT was analyzed by ELISA after extraction. Body weights increased from day 64 until d 114 in both groups, however, at the end of the experiment, mean body mass in the CORT group was significantly lower than in the control group (P < 0.001). Pullets of the CORT group also showed shorter and lighter P5s as well as a retarded molt of the primaries. The supplementation of drinking water with corticosterone increased the average fCORT in the P5s of the CORT pullets compared with the control group (median: 110.3 pg/mm [interquartile range (IQR): 47.2] vs. 10.0 pg/mm [IQR: 2.5], P < 0.001). The results show that experimentally increased systemic corticosterone concentrations over a period of seven weeks in layer pullets are reflected in corticosterone concentrations of feathers grown during that time. This indicates that the measurement of fCORT may be a useful and minimally invasive tool for the evaluation of long-term stress in chicken and provides the basis for further investigations on its use in animal welfare research.

Impact of juçara (Euterpe edulis) fruit waste extracts on the quality of conventional and antibiotic-free broiler meat

Juçara (Euterpe edulis) is a native Brazilian palm tree from the Atlantic Forest, whose fruit-processing waste can present high concentration of antioxidant compounds. This research was assessed to determine the antioxidant potential of juçara waste extracts aiming to reduce the lipid and protein oxidation processes on conventional and antibiotic-free broiler meat throughout 9 d during refrigerated storage. The juçara waste extracts were obtained by microwave-assisted extraction. Two different extracts were tested based on the optimum point obtained when checking total phenolic (TPC) contents (Extract P) and antioxidant activity (Extract A) based on a previous study. The treatments using conventional and antibiotic-free broiler meat included: chicken patties without antioxidant addition (AFBNC and CBNC), with synthetic antioxidant (BHT) (AFBPC and CBPC), with Extract P (AFBEP and CBEP) and with Extract A (AFBEA and CBEA), totaling 8 treatments. Antioxidant activity of extracts along with TPC, flavonoid, anthocyanin, and tannin contents of extracts and patties were assessed. Proximate composition, fatty acid profile, lipid and protein oxidation process, and instrumental color were analyzed in patty treatments. Although both extracts had similar content of TPC and tannin, extract A presented the highest anthocyanin, while extract P exhibited the highest flavonoid. While extract A exhibited the highest antioxidant activity, extract P was highly influential in the stability of lipid oxidative degradation in both types of broiler meat (AFBEP and CBEP), and as successful as BHT (AFBPC and CBPC). In addition, extract P was also able to stabilize protein oxidation in conventional broiler meat (CBEP) from the third day, until the end of the storage period. Therefore, the fruit waste extract P of juçara can be a promising source of natural antioxidants to prevent the oxidative process in conventional and antibiotic-free broiler meat.

Single fluff-spray application of mother hen uropygial secretion analogue positively influences bursa of Fabricius development and the heterophil-to-lymphocyte ratio in ROSS 308 chicks

Stress is an important cause of illness and mortality in chick production. Stressors such as manipulation, absence of maternal care, transport, and housing can lead to welfare issues, immunodepression, and decreased productivity. The mother hen uropygial secretion analogue (MHUSA), a synthetic analog of a maternal semiochemical secretion, has been proven to protect chicks and broilers against stress, significantly reducing the heterophil-to-lymphocyte ratio. The aim of the present study was to test the effects of the MHUSA on chicks' stress when single-sprayed on their fluff at the age of 1 d. Two-hundred eighty ROSS 308 chicks were included in the study. At day 1, each chick received a spray of 200 μL of a 2% MHUSA aqueous solution (140 chicks) or the same amount of the excipient (control group, 140 chicks), and then chicks were housed in 2 separate rooms. To assess the persistence of the MHUSA after this single application, fluff was sampled from 10 chicks every day for 7 d and at day 13 and 19, weighed, placed in dichloromethane, and analyzed by gas chromatography. Blood smears and the bursa of Fabricius were collected every 3 d from 10 chicks of each group for 36 d to assess the heterophil-to-lymphocyte ratio and the bursa weight-to-BW ratio, respectively. Gas chromatography analysis showed that the MHUSA was present on chick fluff until day 5. The statistical analysis revealed that the heterophil-to-lymphocyte ratio was lower in the MHUSA group at day 4, 7, and 9 (P < 0.0001 for day 4 and 7; P = 0.0377 for day 9). The bursa weight-to-BW ratio was significantly higher in the MHUSA group than in the control group from day 4 until day 29. These results confirm the beneficial effects of the MHUSA on chicks' adaptation to the new environment and on bursa of Fabricius development, suggesting its potential role in improving chicks' immune response.

Increased serum levels of advanced glycation end products due to induced molting in hen layers trigger a proinflammatory response by peripheral blood leukocytes

Induced molting (IM), a severe detriment to animal welfare, is still used in the poultry industry in some countries to increase or rejuvenate egg production and is responsible for several physiological perturbations, possibly including reactive oxidative stress, a form of metabolic stress. Because metabolic stress has been shown to induce a proinflammatory response involved in attempts to restore homeostasis, we hypothesized that similar responses followed IM. To confirm this hypothesis, we initially confirmed the establishment of oxidative stress during IM in 75-wk-old layers by demonstrating increased production of advanced glycation end products (AGE). Concomitant with increased oxidative metabolites, cellular stress was demonstrated in peripheral blood leukocytes (PBL) by increased levels of stress gene products (the glucocorticoid receptor, sirtuin-1, and heat shock protein 70 mRNA). Increased expression of stress proteins in PBL was followed by a proinflammatory response as demonstrated by increased levels of proinflammatory gene products (IL-6 and IL-1β mRNA); increased expression of these gene products was also demonstrated in direct response to AGE in vitro, thus establishing a direct link between oxidative and cellular stress. To establish a possible pathway for inducing a proinflammatory response by PBL, we showed that AGE increased a time dependent expression of galactin-3, Toll-like receptor-4, and nuclear factor - κB, all involved in the proinflammatory activation pathway. In vivo, AGE formed complexes with increased levels of circulating acute phase proteins (lysozyme and transferrin), products of a proinflammatory immune response, thereby demonstrating an effector response to cope with the consequences of oxidative stress. Thus, the harmful consequences of IM for animal welfare are extended here by demonstrating the activation of a resource-demanding proinflammatory response.

Effect of transportation and shackling on plasma concentrations of corticosterone and heterophil to lymphocyte ratios in market weight male turkeys in a commercial operation

There is limited information on the effects of stress and/or physiological manipulation on either plasma concentrations of corticosterone (CORT) and/or heterophil: lymphocyte (H : L) ratios in turkeys. The present studies examine the effects of catching/transportation/lairage in a holding shed and shackling on plasma concentrations of CORT and H : L ratios in male market weight turkeys. Plasma concentrations of CORT were increased after transportation and lairage but not further elevated by shackling, irrespective of its duration up to 240 s. In one study, there were increased H : L ratios following catching/placing birds into transportation cages/transportation/lairage. In one study, H : L ratios declined following shackling. It is concluded that while moving turkeys from the farm to immediately before the shackling line is stressful, shackling for up to 4 min was not perceived as more stressful in turkeys. There were also differences between farms/houses for both plasma concentrations of CORT and H : L ratios.

Development and reactivity of the immune system of Japanese quail lines divergently selected for the shape of the growth curve

1. Selection strategies for broilers must balance rapid growth with the welfare and health of animals, strategies must deal with the trade-off with other vital functions.2. Divergent selection of Japanese quail for high (HG) and low (LG) relative body weight gain between 11 and 28 days of age has been conducted to accelerate linear phase growth without influencing the final adult body weight. Higher body growth rate is often connected with a weakened immune system. Therefore, the present study explored the immunological characterisation of quail from HG and LG lines, which differ substantially in their growth rate.3. The trial evaluated the maternal investment to immunologically active substances, cell-mediated immunity stimulated by phytohaemagglutinin (PHA) injection and the acute phase of the immune response to lipopolysaccharide (LPS) administration in three different phases of early postnatal growth.4. Except for higher lysozyme activity in the LG group when compared to the HG line, the maternal investment did not differ between the two lines. Plasma antibody concentrations responded quickly to any change in growth rate in both lines. Overall, it seems that initial rapid growth of the LG line had long-lasting effects on immune responsiveness, even after the growth rate of the HG line escalated during the linear phase of growth.5. The study indicated that changes in the growth rate caused by the selection for growth in meat-type Japanese quail can influence the acute phase of the immune response and development of the immune system.

Evaluation of responses to vaccination of Angus cattle for four viruses that contribute to bovine respiratory disease complex

Although vaccination is an effective measure in reducing the risk of bovine respiratory disease complex (BRDC) in cattle, BRDC losses remain significant. Increasing the efficacy of vaccination depends on elucidating the protective immune response to different antigens included in vaccines, determining the best timing for vaccination, and understanding the impact of the age of the calf on vaccination. This study measured the serum antibodies present in calves following vaccination against 4 viruses commonly associated with BRDC: bovine viral diarrhea virus type 1 and 2 (BVDV1 and BVDV2), bovine respiratory syncytial virus (BRSV), and bovine herpesvirus 1 (BHV1). Serum antibody titers were measured in more than 1,600 calves at 3-wk intervals starting at the time of the first vaccination. This first vaccination occurred at weaning for approximately half of the individuals and 3 wk before weaning for the other half. Dam age (years), time of weaning (initial vaccination or booster vaccination), and age of calf within year-season (days within year-season) classification all were found to have a significant effect on measured traits such as the initial titer and overall response. An increased initial titer was negatively correlated with each response trait (initial, booster, and overall response). Calves that were weaned at initial vaccination had greater overall antibody response to BVDV1 and BVDV2 compared with calves weaned 3 wk before initial vaccination. In contrast, calves given their initial vaccination 3 wk before weaning had greater overall antibody response to BRSV and BHV1 compared with calves that were vaccinated at weaning. Furthermore, the circulating antibody titer at which each virus needed to be below for an individual calf to positively respond to vaccination was determined (log titer of 0.38 for BVDV1, 1.5 for BVDV2, 3.88 for BRSV, and 1.5 for BHV1). This information can be used to improve vaccination protocols to allow for a greater response rate of individuals to vaccination and, hopefully, improved protection.

Behavioral phenotype predicts physiological responses to chronic stress in proactive and reactive birds

Animal species display significant variation in personality traits among individuals, and two main coping styles have been identified and termed "proactive" and "reactive". Further, these coping styles appear to correlate directly with the strength of the physiological stress response exhibited by those individuals. In our study system, white laying hens are reactive, flighty, and exhibit large hormonal and behavioral responses to acute stress, while brown laying hens are proactive, exploratory, and exhibit low hormonal and behavioral responses to acute stress. The objective of the current study was to determine if personality type also corresponds to differences in multiple measures of stress when birds are subjected to a chronic stressor. We tested the responses of hens to chronic stress applied by providing feed according to an unpredictable schedule for 14 days, and measured corticosterone concentrations in circulation, expression of heat shock proteins (HSPs), molecules known to protect cells in response to stress, and the ratios of heterophils:lymphocytes in blood, two immune cells known to change in quantity in circulation during chronic stress. We predicted that white hens would show greater physiological responses to the chronic stress treatment. Plasma corticosterone levels significantly increased after 7 days of treatment and returned to baseline levels on day 14, but did not differ significantly between strains. H:L ratios, on the other hand, were significantly elevated by day 7 of treatment, and increased significantly more in brown hens than white. HSP70 and HSP90 expression levels were significantly higher after stress began in white hens than brown. Our results showed that brown hens were more reactive in one response (H:L ratios) while white hens were more reactive in another (HSP expression). These different reactions to the same stressor may represent different strategies for dealing with the same stressor.