Impact of resveratrol-loaded liposomal nanocarriers on heat-stressed broiler chickens: Effects on performance, sirtuin expression, oxidative stress regulators, and muscle building factors.

Climate change is considered to be the primary cause of heat stress (HS) in broiler chickens. Owing to the unique properties of extracted polyphenols, resveratrol-loaded liposomal nanoparticles (Resv-Lipo NPs) were first explored to mitigate the harmful effects of HS. The dietary role of Resv-Lipo NPs in heat-stressed birds was investigated based on their growth performance, antioxidative potential, and the expression of heat shock proteins, sirtuins, antioxidant, immune, and muscle-building related genes. A total of 250 1-day-old Ross 308 broiler chickens were divided into five experimental groups (5 replicates/group, 10 birds/replicate) for 42 days as follows: the control group was fed a basal diet and reared in thermoneutral conditions, and the other four HS groups were fed a basal diet supplemented with Resv-Lipo NPsI, II, and III at the levels of 0, 50, 100, and 150 mg/kg diet, respectively. The results indicated that supplementation with Resv-Lipo NP improved the growth rate of the HS group. The Resv-Lipo NP group showed the most significant improvement in body weight gain (p < 0.05) and FCR. Additionally, post-HS exposure, the groups that received Resv-Lipo NPs showed restored functions of the kidney and the liver as well as improvements in the lipid profile. The restoration occurred especially at higher levels in the Resv-Lipo NP group compared to the HS group. The elevated corticosterone and T3 and T4 hormone levels in the HS group returned to the normal range in the Resv-Lipo NPsIII group. Additionally, the HS groups supplemented with Resv-Lipo NPs showed an improvement in serum and muscle antioxidant biomarkers. The upregulation of the muscle and intestinal antioxidant-related genes (SOD, CAT, GSH-PX, NR-f2, and HO-1) and the muscle-building genes (myostatin, MyoD, and mTOR) was observed with increasing the level of Resv-Lipo NPs. Heat stress upregulated heat shock proteins (HSP) 70 and 90 gene expression, which was restored to normal levels in HS+Resv-Lipo NPsIII. Moreover, the expression of sirtuin 1, 3, and 7 (SIRT1, SIRT3, and SIRT7) genes was increased (p < 0.05) in the liver of the HS groups that received Resv-Lipo NPs in a dose-dependent manner. Notably, the upregulation of proinflammatory cytokines in the HS group was restored in the HS groups that received Resv-Lipo NPs. Supplementation with Resv-Lipo NPs can mitigate the harmful impact of HS and consequently improve the performance of broiler chickens.

Dietary 1,3-ß-Glucans Affect Growth, Breast Muscle Composition, Antioxidant Activity, Inflammatory Response, and Economic Efficiency in Broiler Chickens.

Recently, researchers have been intensively looking for novel, safe antibiotic alternatives because of the prevalence of many clinical and subclinical diseases affecting bird flocks and the risks of using antibiotics in subtherapeutic doses as feed additives. The present study intended to evaluate the potential use of 1,3-ß-glucans (GLC) as antibiotic alternative growth promotors and assessed the effect of their dietary inclusion on the growth performance, carcass traits, chemical composition of breast muscles, economic efficiency, blood biochemical parameters, liver histopathology, antioxidant activity, and the proinflammatory response of broiler chickens. This study used 200 three-day-old ROSS broiler chickens (50 chicks/group, 10 chicks/replicate, with an average body weight of 98.71 ± 0.17 g/chick). They were assigned to four experimental groups with four dietary levels of GLC, namely 0, 50, 100, and 150 mg kg-1, for a 35-day feeding period. Birds fed diets containing GLC showed an identical different growth rate to the control group. However, the total feed intake (TFI) increased quadratically in the GLC50 and GLC100 groups as compared to that in the control group. GLC addition had no significant effect on the weights of internal and immune organs, except for a decrease in bursal weight in the GLC150 group (p = 0.01). Dietary GLC addition increased the feed cost and total cost at 50 and 100 mg kg-1 doses. The percentages of n-3 and n-6 PUFA in the breast muscle of broiler chickens fed GLC-supplemented diets increased linearly in a dose-dependent manner (p < 0.01). The serum alanine aminotransferase (ALT) level and the uric acid level were quadratically increased in the GLC150 group. The serum levels of total antioxidant capacity, catalase, superoxide dismutase, interleukin-1ß, and interferon-gamma linearly increased, while the MDA level decreased in the GLC-fed groups in a dose-dependent manner. Normal histological characterization of different liver structures in the different groups with moderate round cells was noted as a natural immune response around the hepatic portal area. The different experimental groups showed an average percentage of positive immunostaining to the proinflammatory marker transforming growth factor-beta with an increase in the dose of GLC addition. The results suggest that GLC up to 100 mg kg-1 concentration can be used as a feed additive in the diets of broiler chickens and shows no adverse effects on their growth, dressing percentage, and internal organs. GLC addition in diets improves the antioxidant activity and immune response in birds. GLC help enrich the breast muscle with n-3 and n-6 polyunsaturated fatty acids.

Modulating the Growth, Antioxidant Activity, and Immunoexpression of Proinflammatory Cytokines and Apoptotic Proteins in Broiler Chickens by Adding Dietary Spirulina platensis Phycocyanin.

This study investigated the dietary effect of Spirulina platensis phycocyanin (SPC) on growth performance (body weight (BW), body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR)) at starter, grower, and finisher stages, intestinal histomorphology, serum biochemical parameters, inflammatory and antioxidant indices, and proinflammatory cytokines (tumor necrosis factor-α and caspase-3) immune expression in broiler chickens. In total, 250 one-day-old chicks (Ross 308 broiler) were randomly allotted to five experimental groups (5 replicates/group, 10 chicks/replicate) and fed basal diets supplemented with five levels of SPC (0, 0.25, 0.5, 0.75, and 1 g kg-1 diet) for 35 days. Compared with SPC0 treatment, different SPC levels increased the overall BW and BWG without affecting the total feed consumption. However, the FCR decreased linearly with an increase in supplementation level. The serum levels of total proteins, albumin, globulins, and growth hormone increased linearly by increasing levels of SPC supplementation. Further, SPC supplementation increased the thyroxin hormones without affecting serum glucose and leptin levels. Serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) values decreased in broilers fed SPC0.250 and SPC1 diets. Triglycerides (TG) decreased in SPC0.25-, SPC0.75-, and SPC1-treated groups. Though antioxidant enzyme activities (total antioxidant capacity, catalase, and superoxide dismutase) increased linearly and quadratically, malondialdehyde (MDA) decreased linearly by increasing the SPC level. There was no effect on serum proinflammatory cytokines IL1ß levels. Immunolabelling index of caspase-3 and tumor necrosis factor-α (TNF-α) were downregulated by SPC supplementation. The intestinal histomorphology is represented by increased villus height, the villus height to crypt depth ratio, and numbers of goblet cells in different sections of the small intestine. In conclusion, SPC supplementation is beneficial in broiler chicken diets due to its growth-promoting, antioxidant, and anti-inflammatory properties.

Black Pepper or Radish Seed Oils in a New Combination of Essential Oils Modulated Broiler Chickens' Performance and Expression of Digestive Enzymes, Lipogenesis, Immunity, and Autophagy-Related Genes.

Optimal combinations of essential oils (EOs) can enhance performance and maintain poultry productivity. The effects of EOs with black pepper oil (BPO) or radish seed oil (RSO) on performance and the expression of digestive enzymes, lipogenesis, immunity, and autophagy-related genes in broiler chickens were explored. Six dietary treatments for 300 one-day-old chicks were allocated as follows: controls were fed a basal diet, one group was fed an EO-supplemented diet (1.5 g/kg diet of parsley, mint, and carrot seed oils (1:1:1)), and other groups received Eos + BPO0.25, Eos + BPO0.5, Eos + RSO0.25, and Eos + RSO0.5 treatments, with a basal diet containing EOs plus BPO or RSO at the level of 0.25 or 0.5 g/kg, respectively. Supplementation with 0.5 g/kg of EOs plus BPO or RSO resulted in the most improved maximum BWG and FCR in broiler chickens. The lactobacilli population was increased in Eos + BPO0.5, followed by EOs + RSO0.5, unlike in the control. The highest expression of the CCK and PNLIP genes was identified in the Eos + BPO group. The FAS and ACC genes were upregulated, while the IgA and IL-10 genes were downregulated, with EOs plus RSO or BPO. The group that received Eos + BPO0.5, followed by Eos + RSO0.5, displayed patterns of higher expression for atg5, atg7, and atg12, with lower expression of mTOR. In summary, a new combination of EOs with 0.5 g/kg BPO had potential growth-promoting and immune-boosting effects in broiler chickens.

Reproductive Performance and Culling Rate of Purebred Holstein Cows and Their Crosses With Fleckvieh and Brown Swiss Cows Under Subtropical Conditions.

This study aimed to elucidate the reproductive performance of purebred Holstein (HO) cows with their crosses with Fleckvieh (FV) and Brown Swiss (BS) cows under subtropical conditions. A total of 677 cows [487 HO, 104 HO × FV (HFV); 50% FV and 50% HO and 86 HO × BS (HB); 50% BS and 50% HO] were enrolled in this study. Pure HO cows had significantly greater service per conception (S/C; 3.69), days open (147.9 days), and calving interval (449.6 days), than the HFV (2.89, 116.7, and 407.4 days, respectively) and HB (3.07, 134.3, and 434.2 days, respectively) crossbred cows. At day 28, the conception percentage was significantly greater among HFV crossbred cows vs. pure HO cows [crude odds ratios (COR) = 2.16], but embryonic loss, abortion percentage, calving difficulty, and retained placenta percentage were similar (p > 0.05) among pure HO cows and their crosses. HFV crossbreds had significantly lower incidence of endometritis (COR = 0.70, p = 0.035), mastitis (COR = 0.69, p = 0.015), and ketosis (COR = 0.53, p = 0.004) vs. other cows. HB and pure HO cows had a similar incidence of mastitis, lameness, and ketosis (COR = 0.76, 0.75, and 0.81; p = 0.223, 0.468, and 0.492, respectively). HFV crossbred cows had a lower risk of culling rate than HB crossbred cows. In summary, HFV cows demonstrated the best reproductive performance in terms of S/C, days open, calving interval, conception at 28 days, mastitis percentage, ketosis percentage, and endometritis.

Effects of different feeding regimens with protease supplementation on growth, amino acid digestibility, economic efficiency, blood biochemical parameters, and intestinal histology in broiler chickens.

BACKGROUND: This study was conducted to estimate the impacts of using varied feeding regimens with or without protease supplementation on the growth performance, apparent amino acid ileal digestibility (AID%), economic efficiency, intestinal histology, and blood biochemical parameters of broiler chickens. Three hundred one-day-old chicks (Ross 308 broiler) were randomly allotted to a 3 × 2 factorial design. The experimental design consisted of three feeding regimens; FR1: a recommended protein SBM diet, FR2: a low-protein SBM diet, and FR3: a low-protein diet with the inclusion of 5% DDGS and 5% SFM, with or without protease supplementation (250 mg/kg). RESULTS: Increased feed intake and feed conversion ratio were observed in the FR3 treatment during the starter stage and decreased body weight and body weight gain during the grower stage. However, there was no significant effect of the different feeding regimens, protease supplementation, or interaction on the overall performance. The economic value of diets also remained unaffected by the different feeding regimens, protease supplementation, or interaction. Protease supplementation resulted in lowering the AID% of tryptophan and leucine. Reduced AID% of methionine was evident in the FR2 + VE and FR3 - VE treatments. Histological findings substantiated the FR3 treatment mediated a decrease in the duodenal and jejunal villous height (VH), jejunal villous width (VW), and ileal VW, whereas, increase in the ileal crypt depth (CD). The FR2 + VE treatment reduced the VH:CD ratio in the duodenum. The duodenal CD and the jejunal goblet cell count were reduced as a consequence of protease supplementation. The FR3 + VE treatment documented a rise in duodenal CD, while an increase in the jejunal goblet cell count was observed in the FR3 - VE treatment. The FR3 treatment enhanced the IgM serum levels compared to the FR1 and FR2 treatments. IgM serum levels were also elevated following protease supplementation. FR3 + VE treatment increased IgM serum levels. The highest serum ALP was found in the FR3 treatment, whereas the lowest level was obtained in the FR2 treatment. CONCLUSION: Low-protein SBM-based diets could be used without affecting the birds' growth. Altered morphometric measures of the intestine and increased IgM and ALP levels indicated the low-protein SBM/DDGS-SFM diet-induced damage of the intestinal histoarchitecture and immune system of birds. These different diets and protease supplementation failed to affect economic efficiency positively.

Growth performance, tissue precipitation, metallothionein and cytokine transcript expression and economics in response to different dietary zinc sources in growing rabbits.

The impact of different dietary zinc sources on the growth, serum metabolites, tissue zinc content, economics and relative expression of cytokine and metallothionein genes was evaluated in this study. A total of 120 35-day-old male New Zealand White (NZW) rabbits were randomly distributed into four dietary experimental groups with 10 replicates per group and 3 animals per replicate. The control group was fed basal diet with a Zn-free vitamin-mineral premix; the other three groups received control basal diet supplemented with 50 mg/kg level with zinc oxide (ZnO; as inorganic source), Zn-methionine (Zn-Met; as organic source) and zinc oxide nanoparticles (nano-ZnO). The results indicated that Zn-Met and nano-ZnO groups significantly improved body weight, daily weight gain (DWG), feed conversion ratio (FCR) and nutrient digestibility, as well as decreased mortality, compared to ZnO and control groups. Zn-Met and nano-ZnO significantly reduced serum total cholesterol but did not affect serum proteins and liver function. Nano-ZnO supplemented group also recorded the highest value of serum alkaline phosphatase (ALP), insulin-like growth factor (IGF-1) and lysozymes compared to other groups. Nano-ZnO supplementation had increased hepatic Zn and Cu content and decreased faecal Zn content. Also nano-ZnO group recorded higher expression levels of genes encoding for metallothionein I and metallothionein II, interleukin-2 and interferon-γ in the liver of rabbits. The findings of this study demonstrated zinc nanoparticles, and organic zinc supplementation had improved growth performance and health status of growing rabbits than inorganic zinc oxide.

Efficacy of nano zinc oxide dietary supplements on growth performance, immunomodulation and disease resistance of African catfish Clarias gariepinus.

Zinc (Zn) is an important trace element in fish diets that is required for growth, immunity and antioxidant defense mechanisms. The current study assessed the effects of both organic and nanoparticle zinc oxide (ZnO and ZnO-NPs, respectively) on growth performance, immune response and the antimicrobial effect against Pseudomonas aeruginosa in African catfish Clarias gariepinus. Fish were fed either a control diet or diets supplemented with organic ZnO at concentrations of 20 and 30 mg kg-1 or ZnO-NPs at concentrations of 20 and 30 mg kg-1. After 60 d, a subset of the fish was injected intraperitoneally with 3 × 107 CFU ml-1 of P. aeruginosa. Results showed that body weight gain, feed conversion ratio and specific growth rates were significantly increased in ZnO-NPs20 compared to all other groups. The dietary supplementation with 20 mg kg-1 of ZnO-NPs improved the antioxidant status of fish. Moreover, IgM, lysozyme and nitric oxide showed a significant increase in the fish which received the ZnO-NPs20-supplemented diet. A significant upregulation of growth and stress-related genes was seen in the ZnO-NPs20-supplemented group compared to other groups. However, there was no significant difference in the expression of immune-related genes among ZnO-NPs20, ZnO-NPs30 and ZnO30 groups. These findings highlight the potential use of nano-ZnO for improving growth performance, antioxidant status, immunological status and antibacterial activity against P. aeruginosa in African catfish.

Thermal stress consequences on growth performance, immunological response, antioxidant status, and profitability of finishing broilers: transcriptomic profile change of stress-related genes.

The current study was conducted to investigate the impact of thermal stress on growth performance, blood biomarkers, metabolic hormones, immunological response, antioxidant activity, and expression of stress-related genes in broilers. One hundred and fifty one-day-old chicks (Ross 308) were utilized in this work. On the 21st day of age, birds were subjected to three environmentally controlled treatments with five replicate pens of 10 birds per each, representing an initial density of 10 birds/m2-control: reared in a thermoneutral condition; THS1 and THS2: exposed to 4 and 6 h of daily thermal stress at 40 ± 1 °C, respectively, until the 42 days of age. The results demonstrated that thermal stress for 4 and 6 h significantly reduced (P < 0.001) daily weight gain, daily feed intake, blood leukocyte and lymphocyte counts, serum immunoglobulins (IgM, IgA, IgG), and insulin-like growth factor-1 (IGF-1), while serum levels of aspartate aminotransferase, alanine aminotransferase, glucose, cholesterol, low-density lipoprotein, and lactate dehydrogenase were elevated relative to the thermoneutral group. Additionally, the corticosterone level and the ratio of heterophil:lymphocyte increased significantly (P < 0.001) in thermal-stressed groups. The antioxidant enzymes were affected by thermal stress as represented by a significant decrease in the activity of serum catalase (CAT) and glutathione peroxidase (GSH-Px) along with an increase in malonaldehyde concentration. Thermal stress affected gene expression by upregulating heat shock protein 70, heat shock factors 1 and 3, nuclear factor kappa B, interleukin-4, and uncoupling protein, and downregulating GSH-Px, CAT, and IGF-1 transcript levels. However, no changes were observed in interleukin-2 expression levels. It can be concluded that thermal stress destructively influences productivity, physiological status, and gene expression by upregulating heat shock protein 70, heat shock factors 1 and 3, nuclear factor kappa B, interleukin-4, and uncoupling protein, and downregulating GSH-Px, CAT, and IGF-1 transcript levels of broiler chickens.

Effect of Dietary Medium-Chain α-Monoglycerides on the Growth Performance, Intestinal Histomorphology, Amino Acid Digestibility, and Broiler Chickens' Blood Biochemical Parameters.

This trial was conducted to assess the impact of medium-chain α-monoglycerides, glycerol monolaurate (GML) supplementation on the growth performance, apparent ileal digestibility coefficient (AID%) of amino acids, intestinal histomorphology, and blood biochemical parameters of broiler chickens. Three-day-old chicks (76.82 g ± 0.40, n = 200) were haphazardly allocated to four experimental groups with five replicates for each (10 chicks/replicate). The treatments consisted of basal diets supplemented with four glycerol monolaurate levels; 0, 1, 3, or 5 g kg-1 (GML0, GML1, GML3, and GML5, respectively). Growth performance was determined at three periods (starter, grower, and finisher). Dietary GML had no significant effect on the growth performance parameters (body weight, weight gain, and feed conversion ratio) through all the experimental periods. GML1 diet increased the AID% of leucine and decreased the AID% of arginine. GML1 diet increased the duodenal and jejunal villous height and the jejunal muscle thickness. GML3 and GML5 diets increased the goblet cell count in the duodenum. GML supplementation increased the serum level of high density lipoprotein (HDL)-cholesterol. GML5 diet increased the serum levels of IgM and interleukin 10 compared to the control group. We could conclude that dietary supplementation of glycerol monolaurate can supplement broiler chicken diets up to 5 g kg-1 to enhance the immune status and intestinal histomorphology of birds with no improving effect on growth performance.

Impact of strain and duration of thermal stress on carcass yield, metabolic hormones, immunological indices and the expression of HSP90 and Myogenin genes in broilers.

The aim was to elucidate the effects of strain and the duration of thermal stress (36 °C) on the carcass yield, metabolic hormones, immunological parameters and the relative expression of liver heat shock protein 90 (HSP90) and Myogenin genes. Two hundred and seventy day-old chicks (135 of each breed; Ross 308 and Cobb 500) were used in this trial. The birds were divided into 3 equal groups (CON: thermoneutral condition; S1 and S2 groups were subjected to 4 and 6 h of daily thermal stress, respectively. The relative bursa weight in the thermonuteral Ross broilers, but not Cobb broilers was significantly greater than both heat-stressed groups (P = 0.001). The serum Na and phosphorus levels were significantly decreased when both broiler strains subjected to 6 h of thermals stress (P = 0.020 and 0.022, respectively). A linear decrease in the serum T3 level was recorded in both broiler strains as the duration of thermal stress increases (P = 0.001). In both broiler strains, heat stress up-regulate the expression of liver HSP90 gene compared with the thermoneutral group (P = 0.012). Meanwhile, the S2 group of Ross broilers showed a significantly lower IgG level (P = 0.027). Moreover, thermal stress for 6 h down-regulate the relative expression of Myogenin gene compared with the S1 and thermoneutral groups (P = 0.005). In conclusion, thermal stress for 6 h down-regulate the mRNA expression of liver Myogenin, concomitantly with an increase in the expression of HSP90 gene in both broiler strains. These results could be helpful in the markers assisted selection to develop more heat-tolerant broiler strains.

Impact of lactation stage on milk composition and blood biochemical and hematological parameters of dairy Baladi goats.

The objective of this study was to elucidate the impact of lactation stage on milk composition, hematological and biochemical parameters of dairy Baladi goats under Egyptian conditions. Forty-eight Baladi goats (32.8 ± 2.9 kg of BW) were enrolled in the current study. The lactation period has been divided into three stages; early (DIM less than 80 days), Mid (DIM 80-140 days), and Late (DIM over 140 days). Baladi goats had decreased daily-MY at a rate of 18.4% and 31.9% at mid and late stages of lactation, compared with early stage, respectively (p = 0.001). Furthermore, lactose% decreased significantly with progress of lactation (p = 0.017). Total solids%, however, decreased significantly at early stage of lactation in comparison with mid and late stages (p = 0.022). On the contrary, no significant differences were found in protein, fat and SNF percentages at different stages of lactation (p = 0.836, 0.625 and 0.281, respectively). Serum glucose and total protein were significantly reduced at late stage of lactation in comparison with early and mid stages (p = 0.001 and 0.001, respectively). On the contrary, no significant differences were found for erythrocytes count, hemoglobin, serum cholesterol, catalase and triiodothyronine at different stages of lactation. There were high and positive correlations between daily-MY and serum total protein (r = 0.87, P < 0.01) and triiodothyronine (r = 0.41, P < 0.01). However, negative estimates were reported between daily-MY and triglycerides (r = -0.55, P < 0.01) and cholesterol (r = -0.33, P < 0.05). Our results indicate that dairy Baladi goats produce milk with relatively stable protein, fat and solid not fat (SNF) contents at the different stages of lactation, encouraging the continuous utilization of their milk in processing. Also, dairy Baladi goats seem able to maintain the most vital biochemical parameters.

Growth Performance, Antioxidant Capacity, Lipid-Related Transcript Expression and the Economics of Broiler Chickens Fed Different Levels of Rutin.

The effects of rutin on growth performance, hematological and biochemical profiles, antioxidant capacity, economics and the relative expression of selected antioxidants and lipid-related genes were studied in broiler chickens over 42 days. A total of 200 one-day-old female Ross-308 broiler chickens were distributed into four groups, with five replicates of 10 individuals per replicate. They were fed with 0 (control), 0.25, 0.5 or 1 g rutin/kg supplementation in their basal diet. Dietary rutin supplementation, especially the 1 g/kg diet, increased body weight gain, the protein efficiency ratio (p < 0.001) and both white blood cell and lymphocyte counts (p < 0.001). However, it had no effect on total protein, albumin, globulin, or alanine transaminase. A high concentration of rutin (0.5 and 1 g/kg) also significantly reduced serum total cholesterol, triacylglycerol and low-density lipoprotein cholesterol concentrations (p < 0.001), as well as malondialdehyde concentrations (p = 0.001). A high concentration diet also increased the activity of superoxide dismutase, catalase and glutathione peroxidase. Of the lipid-related genes examined, acetyl CoA carboxylase and fatty acid synthase were significantly down-regulated in the livers of rutin-fed individuals, whereas carnitine palmitoyl transferase 1 and peroxisome proliferator-activated receptor alpha were significantly up-regulated. Therefore, rutin supplementation at 1 g/kg has the potential to improve the productive performance and health status of broiler chickens.

Effects of chronic thermal stress on growth performance, carcass traits, antioxidant indices and the expression of HSP70, growth hormone and superoxide dismutase genes in two broiler strains.

The objective was to investigate the effects of genetic type and the duration of chronic thermal stress (36 °C) on the growing efficiency, carcass traits, antioxidant status, and the expression of liver heat shock protein 70 (HSP70), growth hormone (GH) and superoxide dismutase (SOD) genes. Two hundred and seventy one-day-old chicks (135 male chicks of each breed; Ross 308 and Cobb 500) were used in this work. On the 21st day of age, birds were allocated randomly into 3 equal groups till the 42 days of age (CON:raised in a thermoneutral condition; HS1 and HS2 groups were subjected to 4 and 6 h of daily thermal stress, respectively). Regardless of genetic type, thermal stress decreased the dressing percentage in broilers when compared with the thermoneutral conditions (p = 0.039). In both broiler strains, thermal stress for 6 h (HS2) increased the heterophil to lymphocyte ratio (p = 0.036) and the serum albumin, cholesterol and triglyceride levels (p = 0.023, 0.012 and 0.005, respectively) compared with the thermoneutral group. Under the thermonuteral and heat stress conditions, the Ross broiler chickens showed a significant lower serum triiodothyronine level compared with the Cobb boilers (p = 0.042). It is interesting to note that the expression of HSP70 in the liver of heat-stressed Ross broilers, either 4 or 6 h, was significantly (p = 0.002) higher than that reported in the heat-stressed Cobb broilers. In both broiler strains, the thermal stress for 6 h up-regulate the expression of SOD gene (p = 0.001), but down-regulate the expression of GH gene (p = 0.021) when compared with the CON group. In conclusion, chronic thermal stress down-regulate the mRNA expression of liver GH, concomitantly with an increase in the expression of HSP70 and SOD genes in both broiler strains. This could be useful in the identification of molecular genetic markers to assist in selecting broilers that are more tolerant to heat stress.

Impact of parity on the efficiency of ovulation synchronization protocols in Holstein cows.

The objective of this study was to elucidate the impact of parity on the efficiency of three different protocols to synchronize time of ovulation in Holstein cows. All cows enrolled in this trial were categorized into primiparous and multiparous (M1 = 2-3 and M2 ≥3 parities). Conception (P/AI at Day 28) and pregnancy (P/AI at Day 75) rates in the Presynch and CIDRsynch (31.7% and 35.5%; 26.3% and 28.4%, respectively) groups were significantly greater than that in spontaneous estrus (SE; 24.7 and 20.4%, respectively) group (P = 0.048 and 0.024; 0.041 and 0.011, respectively); however, no significant differences were detected between the SE and Ovsynch group for conception, pregnancy, and embryonic loss rates. Conception and pregnancy rates in the Presynch group decreased from 37.8% and 33.5%, respectively in primiparous cows to 29.6% and 23.1%, respectively in M1 cows (P = 0.022 and 0.007, respectively). However, conception and pregnancy rates using the CIDRsynch regimen were increased from 31.1% and 23.8% in primiparous cows to 41.4% and 34.7% in M1 cows (P = 0.017 and 0.008, respectively), and 40.9% and 33.6% in M2 cows (P = 0.021 and 0.019, respectively). Embryonic loss rate using the CIDRsynch protocol was decreased from 22.9% in primiparous cows to 15.1% and 18.2% in M1 and M2 cows (P = 0.013 and 0.130, respectively). On the contrary, embryonic loss rate using the Ovsynch protocol was increased from 11.5% in primiparous cows to 22.1% and 21.8% in M1 and M2 cows (P = 0.001 and 0.003, respectively). The Cox proportional-hazards model of embryonic loss showed significant associations for parity and season of calving with the hazard of embryonic loss (P = 0.001 and 0.016, respectively). Multiparous cows (M1 and M2) had a higher risk of embryonic loss than primiparous cows (Hazard ratio = 1.32 and 1.89, respectively). Our results indicate that use of the CIDRsynch regimen may achieve satisfactory conception and pregnancy rates in multiparous Holstein cows. However, synchronizing time of ovulation in primiparous cows with use of the Presynch treatment increases the fertility indices.