The Effect of Housing Environment on Commercial Brown Egg Layer Production, USDA Grade and USDA Size Distribution.

Consumer demand for retail cage-free eggs is driving the layer industry towards greater use of extensive housing environments. However, there is limited research on how these environments affect egg production characteristics of brown egg layers, as was the focus of this study. Five housing environments were evaluated under typical industry conditions, including conventional cages, enrichable colony cages, enriched colony cages, cage-free and free-range. Three different brown egg laying strains were housed in the different housing environments and managed according to standard husbandry practices and stocking densities. Data collection for the strains began at 17 weeks of age, with a base period of 28 days for feed weigh backs and egg quality assessments. Housing environment had a highly significant (p < 0.0001) effect on all egg production characteristics measured, including egg production rates (% hen-day and % hen-housed), feed consumption (g/bird/day), feed conversion (egg g/feed g), and mortality rate (%) as well as percent grade A, B, and loss. Previous research revealed better egg production metrics for white egg layers in caged environments than extensive environments. In contrast, we observed brown egg layers had optimum production results for the free-range housing environments, and the poorest performance in enrichable colony cages.

Evaluation of Physical Egg Quality Parameters of Commercial Brown Laying Hens Housed in Five Production Systems.

This study evaluates the effect of housing environment on the egg quality characteristics of brown egg layers as many different environments are currently used in the industry. Battery cages, barren colony cages, enriched colony cages, cage-free, and free-range environments were evaluated. Overall, all egg quality measurements were affected by housing environment (p < 0.01) except for vitelline membrane strength, elasticity, and egg solids. Eggshells and yolks were lightest in barren colony cages and darkest from free-range hens (p < 0.0001). Free-range eggs were heavier than eggs from all other environments (p < 0.0001). Cage-free eggs had lower albumen height and Haugh units than other environments (p < 0.0001). Lastly, cage-free and free-range eggs had stronger eggshells than the other environments (p < 0.0001), and free-range eggs had more elastic eggshells than eggs from conventional battery cages and barren colony cages (p < 0.01). Access to the range seemed to give free-range hens different nutritional advantages, which allowed for the darker yolks and shells. Furthermore, eggs from barren colony cages seemed to exhibit more negative characteristics. Simply adding enrichments to colony cages did not improve or detract from egg quality. From this research, it appears that, as the industry moves toward extensive environments, the egg quality of brown egg layers will improve.

Addition of a protected complex of biofactors and antioxidants to breeder hen diets confers transgenerational protection against Salmonella enterica serovar Enteritidis in progeny chicks.

Addition of vitamins and antioxidants has been long associated with increased immunity and are commonly used in the poultry industry; however, less is known regarding their use in broiler breeder hens. The objective of this study was to determine if feeding a complex of protected biofactors and antioxidants composed of vitamins and fermentation extracts to broiler breeder hens conferred resistance against Salmonella enterica serovar Enteritidis (S. Enteritidis) in the progeny chicks. Three-day-old chicks from control- and supplement-fed hens were challenged with S. Enteritidis and necropsied 4- and 11-days postchallenge (dpc) to determine if there were differences in invasion and colonization. Serum and jejunum were evaluated for various cytokine and chemokine production. Fewer (P = 0.002) chicks from supplement-fed hens had detectable S. Enteritidis in the ceca (32.6%) compared to chicks from control-fed hens (64%). By 11 dpc, significantly (P < 0.001) fewer chicks from supplement-fed hens were positive for S. Enteritidis (liver [36%]; ceca [16%]) compared to chicks from the control hens (liver [76%]; ceca [76%]). The recoverable S. Enteritidis in the cecal content was also lower (P = 0.01) at 11 dpc. In additional to the differences in invasion and colonization, cytokine and chemokine production were distinct between the 2 groups of chicks. Chicks from supplement-fed hens had increased production of IL-16, IL-6, MIP-3α, and RANTES in the jejunum while IL-16 and MIP-1ß were higher in the serum of chicks from the control-fed hens. By 11 dpc, production of IFN-γ was decreased in the jejunum of chicks from supplement-fed hens. Collectively, these data demonstrate adding a protected complex of biofactors and antioxidants to the diet of broiler breeder hens offers a measure of transgenerational protection to the progeny against S. Enteritidis infection and reduces colonization that is mediated, in part, by a robust and distinct cytokine and chemokine response locally at the intestine and systemically in the blood.

The effects of high-oleic peanuts as an alternate feed ingredient on performance, ileal digestibility, apparent metabolizable energy, and histology of the small intestine in laying hens.

We aimed to determine the effects of feeding a high-oleic peanut (HOPN) diet to egg-producing laying hens on egg quality, digestibility, and feed conversion. Three isonitrogenous and isocaloric dietary treatments were formulated with 1) Control diet (CON)-a corn-soybean meal conventional diet with 7.8 % added poultry fat, 2) HOPN diet-dietary inclusion of ~20% coarse-ground whole HOPN, and 3) oleic acid (CON-OA) diet-a control diet supplemented with 2.6% oleic fatty acid oil. Ninety-nine 57-wk-old brown Leghorn laying hens were randomly assigned to 33 animals per treatment. Animals were housed individually for 8 wk. Body and feed weights were recorded weekly and feed conversation ratio was calculated. Bi-weekly, shell eggs were analyzed for quality (yolk color, albumen height, and Haugh unit [HU]). Jejunum samples were collected at week 8 for histomorphometric analysis. Analysis of variance was performed on all variables using a general linear mixed model. Laying hens fed the CON-OA diet produced greater number of eggs relative to those fed the HOPN and control diets (P < 0.05). The roche yolk color value was higher (P < 0.001) in eggs from hens fed the HOPN diet. There were no differences in laying hen performance, eggshell color, eggshell strength, eggshell elasticity and egg albumen height, or egg HU, ileal fat digestibility, or villi surface among treatment groups. However, the apparent metabolizable energy (P < 0.01) and ileal protein digestibility (P = 0.02) were greater in laying hens fed the HOPN diet relative to the CON diet. This study suggests that whole unblanched high-oleic peanuts may be an acceptable alternative feed ingredient for laying hens.

Chicken embryo development: metabolic and morphological basis for in ovo feeding technology.

Broiler embryonic development depends on the nutrients that are available in the egg, which includes mostly water, lipids, and proteins. Carbohydrates represent less than 1%, and free glucose only 0.3%, of the total nutrients. Considering that energy requirements increase during incubation and metabolism is shifted toward the use of glycogen stores and gluconeogenesis from amino acids, extensive muscle protein degradation in the end of incubation can compromise chick development in the initial days after hatch. Significant prehatch changes occur in embryonic metabolism to parallel the rapid embryonic development. Oral consumption of the amniotic fluid begins around 17 d of incubation and promotes rapid development of the intestinal mucosa, which is characterized by morphological changes and increased expression and activity of enzymes and transporters. Furthermore, ingested substrates are stored as nutritional reserves to be used during hatching and in the first week after hatch. At hatch, this limited-nutrient store is directed to the functional development of the gastrointestinal tract to enable assimilation of exogenous nutrients. In ovo feeding is an alternative to deliver essential nutrients to chick embryos at this critical and challenging phase. The improved nutritional status and physiological changes triggered by in ovo feeding can resonate throughout the entire rearing period with significant health and economic gains. The present review addresses the main changes in metabolism and intestinal development throughout incubation, and also addresses scientific advances, limitations and future perspectives associated with the use of in ovo feeding that has been regarded as an important technology by the poultry industry.

The effects of high-oleic peanuts as an alternative feed ingredient on broiler performance, ileal digestibility, apparent metabolizable energy, and histology of the intestine.

Locally grown feed ingredients of high energy and protein content, such as peanuts, maybe economically feasible alternatives to corn and soybean meal in broiler diets. Even though normal-oleic peanuts have been demonstrated to be a viable feed ingredient for poultry, few studies to date have examined the use of high-oleic peanuts (HO PN) as an alternative feed ingredient for broiler chickens. Thus, we aimed to determine the effect of feeding HO PN on broiler performance, nutrient digestibility, and intestinal morphology. Three isocaloric, isonitrogenous experimental diets were formulated with 1) dietary inclusion of ~10% coarse-ground whole HO PN; 2) a corn-soybean meal control diet with 5.5% added poultry fat; and 3) a control diet supplemented with 5.5% oleic fatty acid oil. Three-hundred Ross 708 broilers were randomly placed in 10 replicate pens per treatment with 10 chicks per pen and raised until 42 d. Body weights (BW) and feed intake were determined weekly, and feed conversion ratio (FCR) was calculated. Jejunum samples were collected at 42 d for histomorphometric analysis. Analysis of variance was performed on all variables using a general linear mixed model in JMP Pro14. Broilers in the HO PN group had lower (P < 0.05) BW and higher FCR than other treatment groups at weeks 2 and 6. There were no significant differences in the jejunum villi surface area between the treatment groups. However, broilers fed the HO PN diet had greater (P = 0.019) apparent metabolizable energy relative to the other treatment groups, suggesting improved nutrient uptake of dietary fats and/or carbohydrates in the HO PN treatment group. However, additional studies are warranted to further define the nutritional value of HO PN as an alternative poultry feed ingredient.

Feeding high-oleic peanuts to meat-type broiler chickens enhances the fatty acid profile of the meat produced.

Early feeding trials using peanut meal prepared from normal-oleic peanuts helped to identify peanuts as a suitable alternative feed ingredient for poultry. Yet no studies to date have examined the use of high-oleic peanuts (HO-PN) as a feed ingredient for meat type chickens. Therefore, this study aimed to determine the effect of feeding whole unblanched HO-PN on the fatty acid profile of the meat produced from broilers. At hatch male chicks were randomly placed in raised wire cages, in 10 replicate pens per treatment with 10 chicks per pen, and fed with one of the 3 isocaloric, isonitrogenous diets ad libitum for 42 days: (1) conventional control of soybean meal + corn, (2) 10 to 12% HO-PN and corn diet, or (3) control diet spiked with ≈6.0% oleic acid oil. All body weights (BW) were collected, and broiler selection for processing was determined by individual BW within one-half a standard deviation of the experiment 42-D mean BW, with one bird selected per pen (10 replicate pens per treatment, 3 treatments, 10 birds selected per treatment, yielding a total sample size of 30 birds). Performance was determined weekly and breast samples were analyzed for fatty acid and amino acid profile. All data was analyzed using analysis of variance, with t-test mean comparisons at P < 0.05. BW were similar between broilers fed the HO-PN and control diet, while feed conversion ratio of broilers fed the HO-PN diet was significantly higher at weeks 2, 4, and 6 in comparison to the other treatments (P ≤ 0.03). Broilers fed with HO-PN diet had reduced carcass and pectoralis major weights in comparison to the other treatments. Chicken breast from broilers fed the HO-PN diet had significantly reduced saturated and trans fatty acid content in comparison to the controls (P ≤ 0.0002). Although additional studies must be conducted, this study suggests that feeding whole unblanched HO-PN to broiler chickens may serve as a means to enrich the meat produced with unsaturated fatty acids.

Potential Transfer of Peanut and/or Soy Proteins from Poultry Feed to the Meat and/or Eggs Produced.

Previous studies have demonstrated that allergenic feed proteins from peanuts in the diets of layer hens are not detected in the eggs produced. Hence, in this study, we aimed to determine if soy and/or peanut proteins in poultry feed rations of broiler chickens or layer hens would be transferred or detectable in the meat or eggs produced. To meet this objective, 99 layer hens and 300 broiler chickens were equally divided into treatment groups and fed one of three experimental diets: control soybean meal and corn diet, whole unblanched high-oleic peanut and corn diet (HO PN), or a control diet spiked supplemented with oleic acid (OA) oil. At termination, broiler chickens were processed, and chicken breast samples of the left pectoralis muscle were collected, and eggs were collected from layers. Total protein extracts from pooled egg samples and chicken breast samples were subjected to enzyme-linked immunosorbent assay (ELISA) methods and immunoblotting analysis with rabbit antipeanut agglutinin antibodies and rabbit antisoy antibodies for the detection of peanut and soy proteins. Peanut and soy proteins were undetected in all pooled egg samples and individual chicken breast meat samples using immunoblotting techniques with rabbit antipeanut agglutinin and rabbit antisoy antibodies. Moreover, quantitative ELISA allergen detection methods determined all pooled egg samples and individual meat samples as "not containing" peanut or soy allergens. Therefore, this study helps to evaluate the risk associated with the potential transfer of allergenic proteins from animal feed to the products produced for human consumption.

Meat quality and sensory attributes of meat produced from broiler chickens fed a high oleic peanut diet.

Previous studies have identified peanut meal prepared from normal-oleic peanuts as a suitable and economical ingredient for broiler feed. However, to date, no studies have examined the use of new, high-oleic peanut (HO-PN) cultivars as a feed ingredient for poultry. This project aimed to determine the effect of HO-PNs as a feed ingredient for broiler chickens on the quality and sensory attributes of the meat produced. To test 3 experimental diets, male broiler chicks were randomly placed, at hatch, in raised-wire cages, in 10 replicate pens per treatment with 10 chicks per cage. For 6 wk, chicks were fed, ad libitum, one of the three isocaloric, isonitrogenous diets: (1) a conventional soybean meal plus corn control diet, (2) 10 to 12% HO-PN + corn diet, or (3) a control corn diet spiked with ≈6.0% oleic fatty acid oil (OA). At 42 D, 3 broilers per pen (30 per treatment) were processed to determine meat quality and for consumer evaluation. Carcass weights and breast yields were reduced in broilers fed HO-PN, while leg carcass yields were greater in broilers fed HO-PN in comparison to the other groups. Chicken breast from broilers fed HO-PN had reduced meat-pH, reduced L* color values, and increased cooked loss compared to other treatments. Nevertheless, a group of 100-consumer panelists scored all 3-treatment groups similar in terms of sensory attributes for cooked chicken. While additional studies must be performed, this study suggest that HO-PN may be a suitable broiler feed ingredient.

A novel non-invasive method for evaluating electroencephalograms on laying hens.

The use of electroencephalograms (EEG) to study the avian brain relative to behavior was conducted as early as the 1960's. EEG readings, combined with visual cues, provide the ability to elucidate and correlate behaviors to neurological and physiological changes in a chicken. The use of EEG recordings in animal models require access to the brain to implant electrodes. Having the ability to observe EEG activity on sensible birds without surgical implantation could broaden the research in this area and give further insight related to the hen's state of awareness. The development, construction, and implementation of a minimally invasive EEG electrode placement method is described. After implementation, test animals were exposed to extreme environmental stressors as part of a concurrent depopulation methods study and EEG placement withstood the condition changes and corresponding animal physical activity. Sixteen white commercial laying hens had three monopolar 32-gauge needle electrodes inserted subcutaneously and secured to their head and body. Electrodes were attached to a pre-amplifier which transferred EEG signals to a laptop based recording system. Once the electrodes were in place, the hens were placed in individual treatment/observation chamber then various environmental stressors were applied. Verification that the observed brainwave activity was neural and not muscular was done using a photic stimulation validation test. Behavior observations were recorded to correlate sensible and insensible brainwave activity. The validation test and behavior observations demonstrated the method was successful in measuring EEG in sensible laying hens. The use of a non-surgical method for recording EEG will broaden research capabilities and enhance the understanding of a hen's response its environment, eliminate the need for invasive surgical procedures, and minimizes the confounding components of anesthesia, brain surgery, and recovery. With further refinements, the method could open new avenues in avian behavioral and physiological research.

Effect of Dietary Exogenous Enzyme Supplementation on Enteric Mucosal Morphological Development and Adherent Mucin Thickness in Turkeys.

Anti-nutritional factors (ANFs) in feed ingredients can challenge gut health and reduce nutrient utilization. Birds typically activate their innate immune system as a protective response against the adverse effects of ANF, which often involves the secretion of mucin. Although dietary supplementation of exogenous enzymes are commonly used to alleviate the adverse effects of ANF on apparent nutrient digestibility, little is known about how they affect gut health, particularly in relation to the morphological development and mucin secretion of enteric mucosa. We carried out two trials to examine the effect of dietary supplementation of different types of exogenous enzymes on gut health of by accessing the effect of jejunum morphological development and ileal enteric adherent mucin thickness layer in turkeys. Dietary ß-mannanase supplementation reduced ileal adherent mucin thickness layer (804 vs 823 µg/g; p < 0.05), while a commercial blend of xylanase, amylase, and protease (XAP) reduced ileal adherent mucin layer thickness (589 vs 740 µg/g; p < 0.05); thus reducing the apparent endogenous loss of nutrients. Both enzyme supplements also affected gut morphological characteristics. In comparison to the control treatment, dietary ß-mannanase supplementation improved the jejunum tip width (219 vs 161; p < 0.05), base width (367 vs 300; p < 0.05), surface area (509,870 vs 380, 157; p < 0.05) and villi height/crypt depth ratio (7.49 vs 5.70; p < 0.05), and XAP improved the crypt depth (p < 0.05). In conclusion, dietary supplementation of exogenous enzymes may help alleviate the adverse effects of ANF on nutrient utilization by directly or indirectly removing the mucosal irritation that stimulates enteric mucin secretion.

Effects of dietary macronutrient content on energy metabolism and uncoupling protein mRNA expression in broiler chickens.

The objective of the present study was to investigate the effects of dietary macronutrient ratio on energy metabolism and on skeletal muscle mRNA expression of avian uncoupling protein (UCP), thought to be implicated in thermogenesis in birds. Broiler chickens from 2 to 6 weeks of age received one of three isoenergetic diets containing different macronutrient ratios (low-lipid (LL) 30 v. 77 g lipid/kg; low-protein (LP) 125 v. 197 g crude protein (Nx6.25)/kg; low-carbohydrate (LC) 440 v. 520 g carbohydrate/kg). LP chickens were characterised by significantly lower body weights and food intakes compared with LL and LC chickens (-47 and -38 % respectively) but similar heat production/kg metabolic body weight, as measured by indirect calorimetry, in the three groups. However, heat production/g food ingested was higher in animals receiving the LP diet (+41 %, P<0.05). These chickens also deposited 57 % less energy as protein (P<0.05) and 33 % more as fat. No significant differences in energy and N balances were detected between LL and LC chickens. The diets with the higher fat contents (i.e. the LP and LC diets) induced slightly but significantly higher relative expressions of avian UCP mRNA in gastrocnemius muscle, measured by reverse transcription-polymerase chain reaction, than the LL diet (88 and 90 v. 78 % glyceraldehyde-3-phosphate dehydrogenase respectively, P<0.05). Our present results are consistent with the recent view that UCP homologues could be involved in the regulation of lipid utilisation as fuel substrate and provide evidence that the macronutrient content of the diet regulates energy metabolism and especially protein and fat deposition.

Metabolism of stevioside by chickens.

In intubation experiments (643-1168 mg per animal), most of the stevioside administered to chickens was recovered unchanged in the excreta, and only about 2% was converted into steviol. Neither stevioside nor steviol could be found in the blood. In chronic studies (667 mg of stevioside/kg of feed) with laying hens and meat-type chickens, no significant differences were found in feed uptake, weight gain, and feed conversion as the result of stevioside administration. The egg production and egg composition of laying hens were not influenced. Most of the stevioside taken up was found untransformed in the excreta, and about 21.5% or 7.3% was converted to steviol by meat-type chickens or laying hens, respectively. No stevioside or steviol could be detected in the blood or in the eggs of the different groups of animals. In anaerobic incubation experiments with chicken excreta, only a 20% conversion of stevioside into steviol was found. No harmful effects were observed in the chronic stevioside supplementation experiments nor in the intubation experiments in which very high stevioside doses were given.

Cold-induced enhancement of avian uncoupling protein expression, heat production, and triiodothyronine concentrations in broiler chicks.

The relationships among avian uncoupling protein (avUCP) mRNA expression, heat production, and thyroid hormone metabolism were investigated in 7-14-day-old broiler chicks (Gallus gallus) exposed to a low temperature (cold-exposed chicks, CE) or a thermoneutral temperature (TN). After 7 days of exposure, CE chicks exhibited higher heat production (+83%, P<0.01), avUCP mRNA expression (+20%, P<0.01), and circulating triiodothyronine (T(3)) levels (+104%, P=0.07) for non-statistically different body weights and feed intake between 3 and 7 days of exposure as compared to TN chicks. Plasma thyroxine (T(4)) concentration was clearly decreased in CE chicks (-33%, P=0.06). The lower hepatic inner-ring deiodination activity (-47%) and the higher renal outer-ring deiodination activity (+75%) measured in CE compared to TN chicks could partly account for their higher plasma T(3) concentrations. This study describes for the first time the induction of avUCP mRNA expression by low temperature in chickens, as it has been previously shown in ducklings, and supports the possible involvement of avUCP in avian thermogenesis.

Thyroid status, but not insulin status, affects expression of avian uncoupling protein mRNA in chicken.

The aim of this study was to investigate the hormonal regulation of the avian homolog of mammalian uncoupling protein (avUCP) by studying the impact of thyroid hormones and insulin on avUCP mRNA expression in chickens (Gallus gallus). For 3 wk, chicks received either a standard diet (control group), or a standard diet supplemented with triiodothyronine (T(3); T3 group) or with the thyroid gland inhibitor methimazole (MMI group). A fourth group received injections of the deiodinase inhibitor iopanoic acid (IOP group). During the 4th wk of age, all animals received two daily injections of either human insulin or saline solution. The results indicate a twofold overexpression of avUCP mRNA in gastrocnemius muscle of T3 birds and a clear downregulation (-74%) in MMI chickens compared with control chickens. Insulin injections had no significant effect on avUCP mRNA expression in chickens. This study describes for the first time induction of avUCP mRNA expression by the thermogenic hormone T(3) in chickens and supports a possible involvement of avUCP in avian thermogenesis.