Dietary 25-hydroxy-cholecalciferol and additional vitamin E improve bone development and antioxidant capacity in high-density stocking broilers.

This study aimed to investigate the effects of diets supplemented with 25-hydroxycholecalciferol [25-(OH)D3] and additional vitamin E on growth performance, antioxidant capacity, bone development, and carcass characteristics at different stocking densities on commercial broiler farms. A total of 118,800 one-day-old Arbor Acres broilers were assigned to a 2 × 2 factorial treatment consisting of two dietary vitamin levels (5,500 IU vitamin D3 and 60 IU vitamin E: normal diet, using half 25-(OH)D3 as a source of vitamin D3 and an additional 60 IU of vitamin E: 25-(OH)D3+VE diet) and two stocking densities (high density of 20 chickens/m2: HD and 16 chickens/m2: LD). The experiment lasted for 42 d. The results showed that high-density stocking negatively affected the growth performance of broilers during the first four weeks, whereas the vitamin diet treatment significantly improved the feed conversion ratios (FCR) during the last 2 wk. Vitamin diets increased catalase at 14 and 42 d, and the glutathione peroxidase (GSH-px) levels at 42 d in high-density-stocked broilers. The interaction showed that serum vitamin E levels were significantly improved at 28 d of age in high-density-stocked broilers as a result of the vitamin diets. Stocking density and dietary treatments were found to significantly affect bone development, with the vitamin diet significantly increasing metatarsal length and femoral bone strength in broilers from high-density stocking density at 28 d of age. High stocking density increased the proportion of leg muscles and meat yield per square meter. In general, 25-(OH)D3 and additional vitamin E suppressed oxidative stress and ameliorated the negative effects of high-density stocking on bone development in a commercial chicken farm setting. Vitamin diets improved the FCR of broilers, while high-density stocking resulted in better economic outcomes.

High-density stocking is often associated with animal welfare risks in broilers, mainly in terms of oxidative stress and bone development. Nevertheless, farming at too low a density remains for the most part economically unviable. Modulation of antioxidant capacity and bone development by nutritional strategies in high-density-farmed broilers has proven an effective tool in developing countries. Therefore, the present study investigated the effects of applying diets with a higher biological potency of vitamin D3 25-hydroxycholecalciferol [25-(OH)D3] and a higher concentration of vitamin E on broiler production performance, antioxidant capacity and meat production performance at different densities of stocking under commercial farming conditions. The results indicated that the vitamin dietary treatments suppressed oxidative stress and ameliorated the negative effects of high-density farming on bone development.

Performance, blood biochemistry, carcass fatty acids, antioxidant status, and HSP70 gene expressions in Japanese quails reared under high stocking density: the effects of grape seed powder and meal.

Japanese quails reared under high stocking density (SD) were evaluated for the effects of grape seed powder (GSP) and meal (GSM) supplementation on performance, blood biochemistry, thigh and breast muscle fatty acids, antioxidant status, and HSP70 gene expression. We randomly assigned 288 (15-day-old) quail chicks to six treatment groups in a factorial design (2 × 3) with four replicates, involving two density levels [160 cm2/bird (LD) and 80 cm2/bird (HD)] and three feed forms (FFs) [no supplementation, grape seed powder (3% GSP), grape seed meal (3% GSM)]. SD had a significant effect on live weight, but not on weekly feed intake, daily weight gain, and feed conversion ratio. Serum creatinine and aspartate aminotransferase levels were significantly affected by FF and SD × FF (p < 0.05). A high SD reduced the n-3/n-6 ratio of breast muscle and a significant interaction was found between FF (p < 0.001). The SD × FF interaction reduced the Σn-6 ratio in HDM's thigh muscle, whereas in LDM, the ratio increased (p < 0.01). At high SD, neither GSP nor GSM reduced biological markers of oxidative stress (p > 0.05). Compared to GSP, GSM had higher efficacy at reducing HSP70 levels related to high SD levels. Despite this, at high SD, a diet containing 3% of GSP and GSM was not effective in overcoming oxidative stress. Therefore, more studies using different doses of GSM and GSP in quail diets would be beneficial.

Linking key husbandry factors to the intrinsic quality of broiler meat.

Broiler farming is the fastest-growing animal production sector and broiler meat is the second most-consumed meat in the world. The intensification of broiler production often has a negative impact on the meat quality and carcass characteristics. Consumers, however, expect a quality product from animals reared extensively on farms providing good animal welfare, often intuitively associated with extensive farming practices. Therefore, this literature review investigates how the critical factors contributing to the degree of extensiveness of broiler production affect the quality of meat. We used the data from scientific articles published in the years 2012-2021 to analyze the effect of diet (n = 409), genetics (n = 86), enrichment (n = 25), and stocking density (n = 20) on meat quality and carcass characteristics. Minerals and microelements supplementation in the diet improved all the meat quality aspects: sensory, physical, and chemical in most studies. Minerals and enzymes in the diet had beneficial effects on carcass characteristics, unlike feed restriction and ingredient substitutions. The impact of outdoor access on meat quality and carcass characteristics was most frequently examined, in contrast to the use of perches or effects of litter quality. Overall, enrichment did not affect the meat's sensory or physical parameters, but outdoor access improved its lipid composition. Lower stocking density deteriorated intramuscular fat content, decreased tenderness and juiciness, yet lowered cooking and drip loss, and increased carcass and breast muscle yields. When it comes to genetics, in general, slow growing broiler strains have better meat quality parameters, especially regarding yellowness (b*), redness (a*), cooking and drip loss. Our review shows that the factors which contribute to extensiveness of broiler production systems and birds' welfare also affect meat quality and the carcass characteristics.

Effect of stocking density and vitamin E or zinc supplementation on growth, physiology, gene expression, and economic efficiency of growing broiler chicks.

A total of 636 1-day-old male Cobb chicks were randomly assigned to seven treatments. The chicks were offered feed and water ad libitum throughout the experimental period. The first three groups included different stocking densities of broiler birds (low stocking density, LSD: 23 kg/m2; medium stocking density, MSD: 34 kg birds/m2; and high stocking density HSD: 39 kg birds/m2). The LSD group was considered a control group. The other four groups included MSD or HSD broiler birds supplemented with either Vit E (100 mg/kg DM diet; MSDVE and HSDVE) or Zn (100 mg/kg DM diet; MSDZn and HSDZn) in their basal diet. The main findings indicated that HSD and MSD negatively affected (p < 0.05) all variables under investigation compared with LSD. Compared with LSD, broiler birds in the MSD and HSD groups had lower body weights and higher feed conversion ratios, higher concentrations of blood plasma hormones (triiodothyronine thyroxine and corticosterone), and downregulated expression levels of hepatic growth hormone and insulin-like growth factor-l. In addition, broiler birds stocked at medium or high densities resulted in less economic return and profit. Vit E or Zn supplementation to broiler birds stocked at medium or high densities significantly reversed all adverse effects of HSD (> 23 kg/m2) on growth performance, hormones, and gene expression. It could be recommended that adding Zn at a level of 100 mg/kg per DM diet allows increasing the stocking density of broiler birds from 23 kg/m2 to 34 birds/m2 while maintaining the birds, welfare and economic profit.

Dietary Supplemental Chromium Yeast Improved the Antioxidant Capacity, Immunity and Liver Health in Broilers under High Stocking Density.

This study was conducted to investigate the effects of different levels of yeast chromium on growth performance, organ index, antioxidant capacity, immune performance and liver health of broilers under high stocking density. A total of 684 1-day-old Arbor Acres broilers were selected and fed a common diet from 1 to 22 days of age. At the end of 22 days, broilers with similar weight were randomly divided into six treatments, with six replications in each treatment. The broilers in control groups were fed with a control diet and raised at low stocking density of broilers (14 broilers/m2, LSD) and high stocking density (20 broilers/m2, HSD). The broilers in treatment groups were fed with diets supplemented with 200, 400, 800 and 1600 µg Cr/kg chromium yeast (Cr-yeast) under HSD, respectively. The experimental period was 23~42 days. Compared with the LSD group, the HSD group significantly decreased the liver index (ratio of liver weight to live weight of broilers) of broilers (p < 0.05), the HSD group significantly increased the content of corticosterone (CORT) and the activities of alanine aminotransferase (ALT) and alkaline phosphatase (ALP) and decreased the prealbumin (PA) level in the serum (p < 0.05). HSD decreased the total antioxidant capacity (T-AOC) contents in the serum, liver and breast, serum glutathione peroxidase (GSH-Px) activities, breast total superoxide dismutase (T-SOD) activities and liver catalase (CAT) activities of broilers (p < 0.05). The HSD group significantly increased the total histopathological score (p < 0.05). Compared with the HSD group, adding 200, 400, and 1600 Cr-yeast significantly increased the liver index of broilers (p < 0.05), all HSD + Cr-yeast groups decreased the ALT activities (p < 0.05), and the HSD + 800 group significantly decreased the CORT contents and the ALP activities of the serum (p < 0.05); the HSD + 400, 800 and 1600 groups increased the PA contents of the serum (p < 0.05); HSD + 800 group significantly reduced the tumor necrosis factor-α (TNF-α) and Interleukin-1ß (IL-1ß) contents of the serum (p < 0.05); moreover, the HSD + 400 group increased the GSH-Px activities of the serum (p < 0.05), the T-AOC and the T-SOD activities of the breast (p < 0.05) and the T-AOC and CAT activities of the liver (p < 0.05). Adding 800 Cr-yeast significantly decreased the total histopathological score (degree of hepatocyte edema and inflammatory cell infiltration) under HSD (p < 0.05). In summary, Cr-yeast can improve the antioxidant capacity and immune traits, and liver health of broilers under HSD. Based on the results of the linear regression analysis, the optimal supplementation of Cr-yeast in antioxidant capacity, immunity ability and liver health were at the range of 425.00−665.00, 319.30−961.00, and 800.00−1531.60 µg Cr/kg, respectively.

The effects of mulberry (Morus alba Linn.) leaf supplementation on growth performance, blood parameter, and antioxidant status of broiler chickens under high stocking density.

Background and Aim: A stocking density system in boilers is well known for increasing productivity. However, this system increases stress and affects the growth performance of broilers. Mulberry is a valuable plant with therapeutic applications in traditional medicine; moreover, it reduces free radicals and improves growth performance in broilers. This study was conducted to investigate the effects of mulberry on the blood biochemistry parameters and the antioxidant status of broilers exposed to various raising systems. Materials and Methods: Two hundred and seventy-six 3-week-old male broilers were randomly assigned to nine categories composed of three growing systems: Semi-intensive, low stocking density, and high stocking density. Each group was fed with a control diet mixed with and without 10% mulberry leaf extract; the positive control group was provided with vitamin C. During the study, phytochemical screening of mulberry leaf extract, growth performances, hematological parameters, and antioxidant profiles were measured over the 4 weeks of the treatment. Results: In the high stocking density group, lipid peroxidation gradually increased while antioxidant activities decreased; however, the level of lipid peroxidation was reduced, whereas catalase and superoxide dismutase activities were significantly increased. The growth performance and blood biochemistry were improved after being fed with 10% mulberry leaf extract. Conclusion: This finding indicates that mulberry leaf extract reduced oxidative stress, activated antioxidant enzyme activities, and enhanced broilers' growth performance when raised under stress conditions.

Impacts of tea tree or lemongrass essential oils supplementation on growth, immunity, carcass traits, and blood biochemical parameters of broilers reared under different stocking densities.

The effects of tea tree essential oil (TTEO) and lemongrass essential oil (LGEO) with different stocking densities on the growth performance, biochemical markers, antioxidants, and immunity state of broiler chickens were studied.  Birds were housed at stocking densities of 25, 30, 35, and 40 kg/m2. The treatments were, basal diet without any supplementation, the second and third groups were supplemented with 300 mg TTEO/kg feed, and 300 mg LGEO/kg feed, respectively. Results revealed that increasing stocking density from 25 to 40 kg/m2 significantly reduced body weight and daily weight gain at different ages. The phagocytic index and activity were significantly higher under the lower stocking density (25 kg/m2). Serum amyloid A (SAA), serum or liver transferrin (TRF), or C-reactive protein (CRP) were significant decreased when decreasing stocking density. Increasing stocking density from 25 to 40 kg/m2 resulted in a significant increase in the serum urea, creatinine, uric acid, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), and catalase (CAT) levels. However, there was a significant reduction in antioxidant enzyme activity, including glutathione peroxidase (GPx) and superoxide dismutase (SOD), as stocking density increased. The supplementation of TTEO produced significantly higher body weight and daily weight gain followed by LGEO. Additionally, the mortality rates were reduced in TTEO (27.4%) and LGEO (25%) groups. TTEO or LGEO supplementation significantly improved meat constituents and cellular immunity and reduced serum total lipids, serum and meat cholesterol, and triglycerides, SAA, TRF, and CRP. For all these measured parameters, superior results were obtained when TTEO was used compared to LGEO. TTEO or LGEO supplementation also significantly reduced serum urea, creatinine, uric acid, and the enzymatic activities of LDH, ALT, AST, MDA, and CAT (but not GPx and SOD) in comparison to the control treatment. Overall, our results showed the superiority of TTEO over LGEO as a feed supplement in broiler diets. In conclusion, TTEO treatment offers a better solution for raising broiler chickens in high stocking density.

Hydroxy-Selenomethionine Improves the Selenium Status and Helps to Maintain Broiler Performances under a High Stocking Density and Heat Stress Conditions through a Better Redox and Immune Response.

This study has determined whether hydroxy-selenomethionine (OH-SeMet) exerts a better protective action on broilers against environmental stress than sodium selenite (SS) or seleno-yeast (SY). Day-old male Cobb 500 broilers (12 cages/diet, 9 broilers/cage) were fed a selenium (Se)-deficient diet (0.047 mg/kg) supplemented with SS, SY or OH-SeMet at 0.3 mg Se/kg under a high stocking density and heat stress condition for six weeks. OH-SeMet improved the FCR and Se concentration in the tissues than SS and SY. SY and OH-SeMet both reduced the serum cortisol, T3, IL-6, IgA, IgM and LPS, more than SS, while only OH-SeMet further increased IL-10 and IgG. SY and OH-SeMet improved the intestinal morphology and increased the T-AOC, TXRND, SELENON and OCCLUDIN activities but decreased CLAUDIN2 in the jejunum than SS, while OH-SeMet further improved these values than SY. SY and OH-SeMet both increased SELENOS and TXNRD2 in the muscles than SS, and OH-SeMet further raised T-AOC, GPX4, SELENOP, SELENOW and TXNRD1, and reduced malondialdehyde and protein carbonyl in the muscles than SS and SY. OH-SeMet showed a better ability to maintain the performance and the redox and immune status of broilers under a high stocking density and heat stress challenge than SS and SY.

Effects of stocking density and dietary vitamin C on performance, meat quality, intestinal permeability, and stress indicators in broiler chickens.

The objective of the current study was to investigate the effects of stocking density (SD) and dietary supplementation of vitamin C on growth performance, meat quality, intestinal permeability, and stress indicators in broiler chickens. The study was conducted using a completely randomized design with a 2 × 2 factorial arrangement consisting of 2 different SD and 2 supplemental levels of dietary vitamin C. A total of 1,368 Ross 308 broiler chickens of 21 days of age with similar body weights (BW) were randomly allotted to 1 of 4 treatments with 6 replicates each. Different numbers of birds per identical floor pen (2.0 m × 2.4 m) were used to create 2 different SD levels of low SD (9 birds/m2) and high SD (18 birds/m2). The basal diet was formulated with no supplemental vitamin C to meet or exceed nutrient recommendations of the Ross 308 manual. The other diet was prepared by supplementing 200 mg/kg vitamin C in the basal diet. The study lasted for 14 days. At the end of the study, 3 male birds per replicate were selected to analyze meat quality, intestinal permeability, and stress indicators such as blood heterophil:lymphocyte (H:L) and feather corticosterone (CORT) concentrations. Results indicated that there were no interactions between different SD and dietary supplementation of vitamin C for all measurements. For the main effects of SD, birds raised at high SD had less (p < 0.01) BW, BW gain, and feed intake with increasing stress responses including greater blood H:L and feather CORT concentrations (p < 0.01) than those raised at low SD. Transepithelial electrical resistance in the jejunal mucosa was decreased (p < 0.05) at high SD, indicating an increase in intestinal permeability. However, the main effects of dietary supplementation of 200 mg/kg vitamin C were insignificant for all measurements. In conclusion, high SD of broiler chickens impairs growth performance and intestinal barrier function with increasing stress responses. However, dietary supplementation of vitamin C may have little beneficial effects on broiler chickens raised at the high SD condition used in the present study.

Dietary supplementation of methionine mitigates oxidative stress in broilers under high stocking density.

We aimed to investigate whether dietary supplementation of methionine could mitigate intestinal oxidative injury in broilers under high stocking density (HSD). In the grower phase (d 22-42), 576 broilers with similar body weight were randomly chosen and divided into 8 groups in a 2 × 4 factorial experiment. Two different stocking densities (14 and 20 broilers per m2) were tested with 4 different methionine levels: 0.35%, 0.4%, 0.45%, or 0.5%. Intestinal morphological and oxidative stress markers were assessed at the end of the test period. The results showed that mortality of broilers was significantly higher in the HSD group fed 0.35% methionine diet than the other groups, which was reversed by supplementation with 0.40% to 0.50% methionine. HSD significantly decreased feed intake and daily weight gain. HSD treatment significantly decreased T-AOC, activity of GPX (P < 0.01) and increased the level of PCO (P < 0.01), MDA (P = 0.052) of plasma. The decreased glutathione peroxidase activity in the liver and jejunum caused by HSD was alleviated by additional methionine. Supplementation of methionine increased the ration of GSH/GSSG in the plasma. The jejunum villus height and ratio of villus height to crypt depth under low stocking density conditions with 0.40% methionine diet were the highest, whereas the 0.45% methionine group was the highest under HSD conditions. Thus, additional dietary supplementation of methionine mitigates oxidative stress in broilers under HSD conditions and 0.40% to 0.45% methionine can be applied in cage rearing broiler production for amelioration of oxidative stress caused by HSD.

Dietary 25-hydroxyvitamin D improves intestinal health and microbiota of laying hens under high stocking density.

The high stocking density is a major stress factor that adversely affects the health and performance of poultry. Therefore, the object of this study was conducted to explore whether dietary 25-hydroxyvitamin D (25-OH-D3) could improve gut health of laying hens reared under high stocking density. A 2 × 2 factorial design was used in this 16-week study, in which 800 45-week-old Lohmann laying hens were allocated into two levels of dietary 25-OH-D3 levels (0 and 69 µg/kg) and two rates of stocking densities [506 (low density, LD) and 338 (high density, HD) cm2/hen]. Compared with the layers with LD, the layers with HD had lower crypt depth in duodenum (P(Density) < 0.05), lower short chain fatty acid (propionic and butyric acid) contents in cecum (P(Density) < 0.05), and lower mRNA expression of intestinal barrier associated protein (claudin-1, mucin-1 and mucin-2). Exposed layer to HD also led to lower intestinal antioxidative capacity [superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), and higher malondialdehyde (MDA) content] in small intestine (P(Density) < 0.05), lower bacterial abundance of Bacteroidetes (phylum), Spirochaetes (phylum) and Bacteroides (genus; P(Density) < 0.05), higher bacterial enrichment of Lactobacillaceae (genus) and Firmicutes/Bacteroidetes ratio (P(Density) < 0.05) in cecum. Dietary 25-OH-D3 increased the villus height in duodenum and jejunum (P(25-OH-D3) < 0.05), decreased Chao 1 and ACE indexes in cecum (P(25-OH-D3) < 0.05), and it also up-regulated the mRNA expression of claudin-1, mucin-1 and mucin-2 (P(25-OH-D3) < 0.05). Layers treated with 25-OH-D3 led to an enhanced antioxidative enzyme activity of CAT (P(25-OH-D3) < 0.05). Additionally, the effect of 25-OH-D3 reversed the effect of HD on T-AOC and MDA content (P(Interaction) < 0.05). In HD layers, 25-OH-D3 administration decreased the enrichment of Bacteroidetes (phylum), increased Firmicutes (phylum), and Firmicutes/Bacteroidetes ratio (P(Interaction) < 0.05). These results suggest that supplementing 25-OH-D3 in diets may elevate gut health through the improvement of intestinal barrier function, antioxidant capacity and cecal microbiota composition in laying hens with high stocking density.

Effects of alpha-lipoic acid on the behavior, serum indicators, and bone quality of broilers under stocking density stress.

The objective of present study was to investigate the effects of alpha-lipoic acid (ALA) dietary supplementation on the behavior, physiological and oxidant stress indicators, and bone quality in broilers under high stocking density (HSD) stress. A total of one thousand eight hundred 22-day-old Arbor Acres male broiler chicks were randomly allocated to 18 pens (2.97 × 2.03 m) in 3 groups: 14 birds/m2 (NSD, normal stocking density) or 18 birds/m2 (HSD) or 18 birds/m2 plus 300 mg/kg ALA dietary supplement (HSD + ALA, high stocking density + alpha-lipoic acid). Each treatment had 6 replicates, and the experiment lasted 3 wk. The HSD group was significantly lower than the NSD group (P < 0.05) in the frequency of eating, walking, and preening behavior. The alkaline phosphatase activity and serum calcium content were significantly higher, and the parathyroid hormone (PTH) level was significantly lower in the HSD group than in the NSD group (P < 0.05). When compared with the NSD group, the HSD group showed an increase (P < 0.05) in serum heterophil/lymphocyte ratio (H/L ratio), corticosterone (CORT), malondialdehyde (MDA) content, and catalase (CAT) activity, whereas a decrease (P < 0.05) in total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) concentrations. The HSD group was also significantly lower (P < 0.05) than the NSD group in the tibia and femur breaking strength, bone mineral density, and BMC. Importantly, the addition of ALA into the diets of the HSD group enabled the HSD + ALA group to recover to the levels of NSD group (P > 0.05) in the standing and preening behavior, alkaline phosphatase activity, PTH concentration, H/L ratio, CAT, T-AOC, MDA, SOD, and GSH-Px. These results indicate that the increase of stocking density lowered the bone quality, increased the physiological and oxidative stress indicators, and modified the behavior of broilers, whereas ALA dietary supplementation could counteract the reduction in the performance and physiological responses of broilers under high-density environmental stress.

Transcriptome analysis reveals a molecular understanding of nicotinamide and butyrate sodium on meat quality of broilers under high stocking density.

BACKGROUND: In recent years, increased attention has been focused on breast muscle yield and meat quality in poultry production. Supplementation with nicotinamide and butyrate sodium can improve the meat quality of broilers. However, the potential molecular mechanism is not clear yet. This study was designed to investigate the effects of supplementation with a combination of nicotinamide and butyrate sodium on breast muscle transcriptome of broilers under high stocking density. A total of 300 21-d-old Cobb broilers were randomly allocated into 3 groups based on stocking density: low stocking density control group (L; 14 birds/m2), high stocking density control group (H; 18 birds/m2), and high stocking density group provided with a combination of 50 mg/kg nicotinamide and 500 mg/kg butyrate sodium (COMB; 18 birds/m2), raised to 42 days of age. RESULTS: The H group significantly increased cooking losses, pH decline and activity of lactate dehydrogenase in breast muscle when compared with the L group. COMB showed a significant decrease in these indices by comparison with the H group (P < 0.05). The transcriptome results showed that key genes involved in glycolysis, proteolysis and immune stress were up-regulated whereas those relating to muscle development, cell adhesion, cell matrix and collagen were down-regulated in the H group as compared to the L group. In contrast, genes related to muscle development, hyaluronic acid, mitochondrial function, and redox pathways were up-regulated while those associated with inflammatory response, acid metabolism, lipid metabolism, and glycolysis pathway were down-regulated in the COMB group when compared with the H group. CONCLUSIONS: The combination of nicotinamide and butyrate sodium may improve muscle quality by enhancing mitochondrial function and antioxidant capacity, inhibiting inflammatory response and glycolysis, and promoting muscle development and hyaluronic acid synthesis.

Integrated biomarker parameters response to the toxic effects of high stocking density, CuSO4, and trichlorfon on fish and protective role mediated by Angelica sinensis extract.

The present study explored the protective role of dietary the extract of Angelica sinensis (EAs) on high density, CuSO4, or trichlorfon-treated Crucian carp (Carassius auratus auratus). Firstly, the study showed that the optimum density for growth and growth inhibition was 0.49 and 0.98 fish L-1 water, respectively. Dietary EAs relieved the high density-induced growth inhibition in Crucian carp. The appropriate concentration of EAs for recovery of growth was estimated to be 4.30 g kg-1 diet in high-density fish. Moreover, high density decreased both digestive and absorptive enzyme activities and increased lipid oxidation in digestive organs, suggesting the ability of high density to induce oxidative damage. However, dietary EAs inhibited the oxidative damage through elevating ROS scavenging ability and enzymatic antioxidant activity in digestive organs. Secondly, our data demonstrated that the appropriate concentration of CuSO4 to induce the decrease in feed intake (FI) was 0.8 mg Cu L-1 water. Dietary EAs returned to FI of Crucian carp treated with CuSO4. The appropriate concentration of EAs for recovery of FI was estimated to be 4.25 g kg-1 diet. Moreover, dietary EAs suppressed the CuSO4-induced decrease in digestion and absorption capacity and increase in protein metabolism in digestive organs of Crucian carp. Finally, the present results suggested that dietary EAs inhibited the trichlorfon-induced rollover (loss of equilibrium) in Crucian carp. The appropriate concentration of EAs for inhibition of rollover was estimated to be 4.18 g kg-1 diet. Moreover, trichlorfon stimulated not only the decrease in energy metabolism but also lipid and protein oxidation, suggesting that trichlorfon caused loss of function and oxidative damage in muscles of fish. However, dietary EAs improved muscular function and inhibited oxidative damage via quenching ROS and elevating non-enzymatic and enzymatic antioxidant activity in muscles of trichlorfon-induced fish. So, EAs could be used as an inhibitor of high density, CuSO4, and trichlorfon stress in fish.

Effect of dietary 25-hydroxycholecalciferol supplementation and high stocking density on performance, egg quality, and tibia quality in laying hens.

This study was conducted to determine the effects of 25-hydroxycholecalciferol (25-OH-D3) on performance, egg quality, tibia quality, and serum hormones concentration in laying hens reared under high stocking density. A total of 800 45-week-old Lohmann laying hens were randomly allotted into a 2 × 2 factorial design with 2 levels of dietary 25-OH-D3 levels (0 and 69 µg/kg) and 2 rates of stocking densities [506 (low density) and 338 (high density) cm2/hen]. Laying hens were monitored for 16 wk. High stocking density decreased laying rate, egg weight, and feed intake compared with low stocking density (P < 0.01) during 1 to 8 wk and 1 to 16 wk. Overall, high stocking density increased eggshell lightness value and decreased shell redness and yellowness value, strength, thickness, and relative weight compared with low stocking density (P < 0.05). Dietary supplementation with 25-OH-D3 reduced the value of the eggshell lightness and increased its yellowness and eggshells weight (P ≤ 0.05). The increase in eggshell thickness was more pronounced when 25-OH-D3 was supplemented to layers under high stocking density (interaction, P < 0.05). Layers under high stocking density had lower ash content and calcium content in the tibia than layers under low stocking density (P = 0.04); dietary 25-OH-D3 increased tibia strength compared with no addition (P = 0.05). Layers under high stocking density had higher serum concentrations of 25-OH-D3, corticosterone (CORT), lipopolysaccharide (LPS), and osteocalcin (OC; P < 0.05), lower content of parathyroid hormone (PTH) compared with layers under low stocking density (P < 0.01). Dietary 25-OH-D3 increased serum concentration of 25-OH-D3, carbonic anhydrase (CA), and calcitonin (CT) (P < 0.01) and reduced corticosterone, lipopolysaccharide and osteocalcin concentration (P ≤ 0.05). The increase effect in PTH was more pronounced when 25-OH-D3 was supplemented to layers under high stocking density (interaction, P = 0.05). Overall, the results gathered in this study indicate that high stocking density result in reducing production performance, shell color and quality, and tibia health, whereas dietary 25-OH-D3 was able to maintain tibia health and to mitigate the negative impact of high stocking density on productive performance.

Supplemental methionine and stocking density affect antioxidant status, fatty acid profiles, and growth performance of broiler chickens.

Broilers stocked in high densities may be prone to oxidative and inflammatory insults, resulting in impaired health status, growth performance, and meat quality. This study was to determine if 30% extra supplemental dl-methionine alleviated or prevented those adverse effects of a higher stocking density in broiler chickens. A total of 560 male Cornish Cross cockerels (day old) were divided into four groups: two stocking densities (9 and 12 birds/m2) and two supplementations of methionine (grower: 2.90 or 3.77 g/kg and finisher: 2.60 or 3.38 g/kg). Growth performance was recorded weekly. Blood and tissues were sampled at the end of each period. High stocking density decreased (P < 0.05) body weight and growth performance of growers and (or) finishers. Those differences were partially attenuated by the extra methionine supplementation. The high methionine elevated (P < 0.05) glutathione (GSH) concentration in the thigh at both ages (> 24%). The high stocking density elevated (>28%, P < 0.05) glutathione concentration in the plasma, breast, and thigh of growers, but decreased (P < 0.05) it in the liver of growers and thigh of finishers. Interaction effects (P < 0.05) between dietary methionine and stocking density were found on activities of the antioxidant enzyme glutathione S-transferase in the liver of growers and breast, thigh, and adipose tissue of finishers. The interaction effect was also found on activities of glutathione peroxidase and superoxide dismutase in the thigh of growers. The extra methionine decreased (P < 0.05) hepatic gene expression of heat shock protein 90 (18%) and thigh and breast malondialdehyde concentrations of the finishers (35%). In conclusion, the 30% extra dl-methionine supplementation was able to partially mitigate adverse effects caused by the higher stocking density and to improve the redox status of the broilers.

Effects of nicotinamide and sodium butyrate on meat quality and muscle ubiquitination degradation genes in broilers reared at a high stocking density.

This study was conducted to investigate the effects of supplementation with nicotinamide (NAM) and sodium butyrate (BA) on meat quality and expression of muscle development genes in broilers reared at a high stocking density. A total of 567, 21-day-old AA broilers were randomly assigned to 5 treatment groups and 2 control groups, with 7 replicates of each group. The control groups included a low stocking density (LD; 12.9 birds/m2) and were fed a basal diet. The treatment groups were kept at a high stocking density (HD; 18.6 birds/m2) and received either a low dose of NAM (50 mg/kg; treatment LN), a high dose of NAM (100 mg/kg; treatment HN), a low dose of BA (500 mg/kg; treatment LB), a high dose of BA (1,000 mg/kg; treatment HB), or a compound supplement (50 mg/kg NAM+500 mg/kg BA; treatment COMB); broilers were reared till 42 D of age. The control groups were kept at HD or at LD (12.9 birds/m2) and were fed a basal diet. The heterophil-to-lymphocyte ratio was significantly higher in the HD control group than that in the LD group; this ratio was significantly lower in treatments LN, HN, HB, and COMB than that in the HD control group. The lightness of breast muscles at 45 min and 24 h after slaughter was significantly higher in the HD group than that in the LD group, and the HD group showed the highest drip loss at 24 h and 48 h. Lightness and drip loss were lower in the HN, LB, and COMB treatments than those in the HD group. HD rearing significantly reduced gene expression of myogenic regulatory factor 5 (MYF5) while significantly increased expression of the protein ubiquitin degradation genes FBXO9, FBXO22, and FBXO32. All treatments significantly reduced FBXO9 and FBXO32 expression. Our results suggest dietary supplementation with NAM and BA can improve meat quality of broilers under high stocking density by upregulating the expression of myogenic genes, and inhibiting protein ubiquitination.

Effect of dietary l-carnitine supplementation and energy level on oxidant/antioxidant balance in laying hens subjected to high stocking density.

This study aimed to investigate the effect of l-carnitine and energy level and on oxidant/antioxidant balance in laying hens subjected to high stocking density. A total of 176, 32-week-old laying hens were assigned to eight groups with four replicates and hens in four groups were placed at the normal stocking densities of 500 cm2 /hen (four hens per cage) and in the remaining four groups were placed at the high stocking densities of 287.5 cm2 /hen (seven hens per cage). Hens received diets of high (2,850 kcal/kg ME) or normal (2,650 kcal/kg ME) energy which are supplemented with 0 or 200 mg/kg l-carnitine for 70 days. Results showed that exposure to high stocking density increased (p < .05) plasma malondialdehyde (MDA) and nitric oxide (NO) levels and decreased (p < .05) erythrocyte superoxide dismutase (SOD), catalase (CAT) and superoxide dismutase (GPx) activities. l-carnitine supplementation increased (p < .05) erythrocyte SOD, CAT and GPx activities, and decreased (p <.05) MDA and NO level in high stocking densities. The oxidan/antioxidan balance of birds was not influenced by increasing dietary energy level. The results of the present study indicate that the supplementation of l-carnitine to the birds subjected to high stocking density could effectively reverse the negative effects of high stocking density by improving oxidant/antioxidant balance. Therefore, l-carnitine supplementation at level of 200 mg/kg to diet may be as a favourable alternative to deal with oxidative stress caused by high stocking density in laying hens.

Effect of stocking density and dietary tryptophan on growth performance and intestinal barrier function in broiler chickens.

The objective of the present experiment was to investigate the effect of stocking density (SD) and dietary supplementation of crystalline tryptophan (Trp) on growth performance and intestinal barrier function in broiler chickens raised in a floor pen. The experiment was conducted using a completely randomized design with a 2 × 2 factorial arrangement consisting of 2 different SD and 2 supplemental levels of dietary Trp. A total of 1,140 Ross 308 broiler chickens at 21 d of age were allotted to 1 of 4 treatments with 5 replicates. Low SD (9 birds/m2) and high SD (18 birds/m2) were achieved by raising different number of birds per identical floor pen (2.0 m × 2.4 m). The basal diet was formulated with no supplemental Trp in diets to meet or exceed nutrient recommendation of the Ross 308 manual. The calculated concentrations of total Trp and digestible Trp in the basal diet were 0.19 and 0.16%, respectively. The other diet was prepared by adding 0.16% crystalline Trp to the basal diet. Diets were fed to birds for 21 d. At the end of the experiment, 2 birds per replicate were euthanized to collect tissue samples for further analyses. Results indicated that there were no interactions between SD and dietary Trp for all measurements. For the main effects, birds raised at a low SD had greater (P < 0.01) body weight gain, feed intake, and feed efficiency than those raised at a high SD. However, supplementation of dietary Trp had no effect on broiler performance. Furthermore, there were no main effects of SD and dietary Trp on intestinal barrier functions. In conclusion, broiler chickens raised in a floor pen with a high SD (18 birds/m2) have decreased growth performance with little changes in intestinal barrier functions. Supplementation of dietary Trp at 0.16% has no positive effect on broiler chickens raised in a floor pen with either a low or high SD.

Effects of Cassia abbreviata extract and stocking density on growth performance, oxidative stress and liver function of indigenous chickens.

The objective of the study was to investigate the effect of stocking density and extract from Cassia abbreviata stem bark on growth performance, oxidative stress and liver function of indigenous chickens. A total of 420 1-day-old female Ovambo chicks with initial body weight of 0.32 ± 0.036 kg (mean ± SD) were used in the study. Birds, which were cooped in stocking densities consisting 5, 10 and 20 birds/m2, were orally administered with 0, 50, 200 and 500 mg/kg of extract from C. abbreviata stem bark. Each stocking density per dosage level of extract was repeated three times. Average feed intake was lower (P < 0.05) in birds housed at 20 birds/m2. There was a low (P < 0.05) average daily gain in birds housed at 20 birds/m2. Malondialdehyde was higher (P < 0.05) in 20 birds/m2. Average daily gain was high (P < 0.05) in birds administered with 0 and 50 mg/kg of C. abbreviata stem bark extract. Birds administered with 0 and 50 mg/kg of C. abbreviata stem bark extract had a higher (P < 0.05) gain to feed ratio. Birds dosed with 500 and 200 mg/kg had high (P < 0.05) superoxide dismutase activity. Birds administered with 500 mg/kg of C. abbreviata stem bark extract had the lowest (P < 0.05) malondialdehyde. A 500 mg/kg of stem bark extract from C. abbreviata resulted to higher (P < 0.05) activities of aspartate transaminase and alanine transaminase. There was a significant (P < 0.05) interaction between the stocking density and C. abbreviata extract on catalase activity. High stocking density of 20 birds/m2 reduced growth performance and induced stress in indigenous chickens. High dosage of level 500 mg/kg of stem bark extract of C. abbreviata reduced oxidative stress while depressing growth performance and causing hepatotoxicity in birds. There is a need to precisely determine the maximum dosage level of C. abbreviata extract to improve growth performance and reduce oxidative stress and hepatotoxicity in indigenous chickens in high stocking density.