Acinetobacter baumannii: an evolving and cunning opponent

Acinetobacter baumannii is one of the most common multidrug-resistant pathogens causing nosocomial infections. The prevalence of multidrug-resistant A. baumannii infections is increasing because of several factors, including unregulated antibiotic use. A. baumannii drug resistance rate is high; in particular, its resistance rates for tigecycline and polymyxin—the drugs of last resort for extensively drug-resistant A. baumannii—has been increasing annually. Patients with a severe infection of extensively antibiotic-resistant A. baumannii demonstrate a high mortality rate along with a poor prognosis, which makes treating them challenging. Through carbapenem enzyme production and other relevant mechanisms, A. baumannii has rapidly acquired a strong resistance to carbapenem antibiotics—once considered a class of strong antibacterials for A. baumannii infection treatment. Therefore, understanding the resistance mechanism of A. baumannii is particularly crucial. This review summarizes mechanisms underlying common antimicrobial resistance in A. baumannii, particularly those underlying tigecycline and polymyxin resistance. This review will serve as a reference for reasonable antibiotic use at clinics, as well as new antibiotic development

Three-Dimensional Organization of Chicken Genome Provides Insights into Genetic Adaptation to Extreme Environments

The high-throughput chromosome conformation capture (Hi-C) technique is widely used to study the functional roles of the three-dimensional (3D) architecture of genomes. However, the knowledge of the 3D genome structure and its dynamics during extreme environmental adaptations remains poor. Here, we characterized 3D genome architectures using the Hi-C technique for chicken liver cells. Upon comparing Lindian chicken (LDC) liver cells with Wenchang chicken (WCC) liver cells, we discovered that environmental adaptation contributed to the switching of A/B compartments, the reorganization of topologically associated domains (TADs), and TAD boundaries in both liver cells. In addition, the analysis of the switching of A/B compartments revealed that the switched compartmental genes (SCGs) were strongly associated with extreme environment adaption-related pathways, including tight junction, notch signaling pathway, vascular smooth muscle contraction, and the RIG-I-like receptor signaling pathway. The findings of this study advanced our understanding of the evolutionary role of chicken 3D genome architecture and its significance in genome activity and transcriptional regulation

Effects of dietary supplemented of γ-amino butyric acid on growth performance, blood biochemical indices and intestinal morphology of yellow-feathered broilers exposed to a high temperature environment

This experiment was conducted to study the effects of γ-amino butyric acid (GABA) on growth performance, blood biochemical indices and intestinal morphology of yellow-feathered broilers exposed to a high temperature environment. One hundred and forty four, 28-day-old male yellow-feathered broilers were separated into 2 groups with 6 replicates and 12 birds per replicate. The two experimental groups included: control group, which fed the basal diet, and GABA supplemented group, which fed the basal diet supplemented with 100 mg/kg GABA. After 7 days of feeding experimental diet at 26 °C, birds were fed the experimental diet and exposed to a high temperature environment at 35 °C and 60% RH for 14 days. Results revealed that average daily gain (ADG, p = .004) and average daily feed intake (ADFI, p = .003) of the GABA group were higher than control group, feed: gain ratio (F/G; p = .023) and mortality (p = .042) were lower than control group. The serum levels of glucose (GLU; p = .016), total cholesterol (T-CHO; p = .001), and low density lipoprotein (LDL; p = .001) as well as the activities of aspartate-aminotransferase (AST; p = .008), lactate dehydrogenase (LDH; p = .042) and creatine kinase (CK; p = .032) of the GABA group were lower than control group, while villus length (p = .016) of jejunum was higher than control group. In conclusion, adding 100 mg/kg GABA to diet can improve growth performance, reduce serum intracellular enzyme activities, protect the organs and intestinal morphology of yellow-feathered broilers exposed to a high temperature environment during 36-49 days of age.Highlights GABA improves growth performance of yellow-feathered broilers exposed to a high temperature environment. GABA protects the intestine of yellow-feathered broilers exposed to a high temperature environment

Effects of cyclic heat stress on the phenotypic response, meat quality and muscle glycolysis of breasts and thighs of yellow-feather broilers

An experiment was conducted to evaluate the effects of cyclic heat stress on phenotypic response, meat quality and muscle glycolysis of broiler. One hundred and eighty 35-day-old male Xueshan broilers with similar BW were randomly selected and exposed to either thermal neutral (TN; 23 °C, 55–60% RH, n = 6) or heat stress conditions (CHS; cyclic temperatures of 35 °C from 10:00 to 18:00, 32 °C from 18:00 to 20:00, 28 °C from 20:00 to 08:00, and 32 °C from 08:00 to 10:00 at 40–45% RH, n = 6) for 7 days. Relative to broilers under thermoneutral conditions, broilers subjected to cyclic heat stress had an overall increase in rectal temperature and respiration rate (p < .001, p < .001, respectively), and a reduced body weight, average daily gain, average feed intake and feed conversion ratio (p = .001, p < .001, p < .001, p = .002, respectively). A higher L* value was obtained from both the breast and thigh muscle of broilers under high temperatures (p = .022 and p = .009, respectively). Furthermore, the thigh muscle of broilers exposed to high temperatures showed a higher hexokinase activity than that of broilers exposed to thermal neutral conditions (p = .014). The results indicate that cyclic heat stress significantly lowers Xueshan broiler production performance and meat quality but has no significant effect on the chemical composition and glycolytic process of the meat.Highlights Cyclic heat stress decreases body weight, average daily weight gain, average feed intake and feed conversion ratio in yellow-feather broilers. Cyclic heat stress decreases the weight, physicochemical characteristics of breast and thigh meat in yellow-feather broilers. Cyclic heat stress increases hexokinase activity to mobilize more glucose to supply the energy for aerobic metabolism in yellow-feather broilers

Supplemental dietary genistein improves the laying performance and antioxidant capacity of Hy-Line brown hens during the late laying period

ABSTRACT: The present study evaluated the effects of 3 supplemental levels of dietary genistein ingested during the late laying period (66–73 wk) of laying hens. A total of 384 Hy-Line brown hens (66 wk old) were randomly divided into 4 groups (6 replicates of 16 hens in each group), the basal diet group (CON), and groups for the basal diet supplemented with 80, 120, and 400 mg/kg of genistein, G1, G2, and G3, respectively. The results of the present study showed an increased laying rate in groups G2 and G3 (linear, P < 0.01), and decreased feed-egg ratios (linear, P < 0.05) and broken egg rate (P < 0.01) in all genistein-treated groups compared with the CON group. Moreover, the G2 group showed an increase in eggshell strength and ratio (linear, P < 0.05), whereas all genistein-treated groups saw a decrease in the L* value (linear, P < 0.01) and an increase in the a* value (linear, P < 0.05) compared with the CON group. Additionally, all genistein-treated groups had an increase in the total antioxidant capacity of plasma (linear, P < 0.05), along with reduced plasma, ovarian, and yolk malondialdehyde levels (linear, P < 0.05), compared with the CON group. The G2 group had an increase in both the superoxide dismutase activity of plasma (P < 0.01) and the total antioxidant capacity of the ovaries (linear, P < 0.05), compared with the CON group. The G3 group had an increase in both the glutathione peroxidase concentration of plasma (linear, P < 0.05) and the total antioxidant capacity of the ovaries (linear, P < 0.01), compared with the CON group. The transcript levels of nuclear factor erythroid 2-related factor 2, superoxide dismutase 1, and catalase were increased in all of the genistein-treated groups (P < 0.05) compared with the CON group, whereas heme oxygenase 1 and glutamate-cysteine ligase modifier subunit were increased only in the G2 group (P < 0.05). In conclusion, supplementation with 120 mg/kg dietary genistein had the best effect on improving the laying rate, eggshell quality, and antioxidant capacity in Hy-Line brown hens during the late laying period

Effects of starter feeding time on body growth and viscera development of newly hatched chicks

The experiment was conducted to investigate the effects of starter feeding time on body growth and viscera development of newly hatched chicks. A total of 1080 Yangzhou chicks with similar weight derived from 1800 eggs were selected in this experiment. These chicks were randomly assigned to six groups (1, 2, 3, 4, 5 and 6) according to six feeding schedules (fasting for 12, 24, 36, 48, 60, 72 hours posthatch), with 3 replicates per group and 60 chicks (30 males and 30 females) per replicate. After fasting, all birds were fed a crumbled starter feedstuff ad libitum until 6 days of age. At 0, 1, 2, 3, 4, 5 and 6d posthatch, eight chicks (4 males and 4 females) per replicate of each experimental group were randomly selected and individually weighed. Yolk sac, liver, heart, pancreas, bursal and small intestine of each chick were taken out and weighed; the length of small intestine, moreover, was measured. Results showed that food deprivation reduced body weight (BW) of experimental chicks; furthermore BW decreased more and more with a prolonged fasting time. At 6 d of age, the BW of the former five groups was higher than that of the Group 6 (P<0.05). At the same time, the growth of viscera apparatuses was influenced by different starter feeding times. There was a significant effect of fasting for 72h posthatch on BW, small intestine weight and length, liver, heart, pancreas and bursal weight. The viscera weights of the former three groups (fasting for 12-36h) were, respectively, more than that of latter three groups (fasting for 48-72h) in different ages (P<0.05). Results of the present study demonstrated that the feasible starter feeding time should be within 36h posthatch, and the maximum fasting period could not exceed 60h posthatch

Effects of Clostridium butyricum on breast muscle lipid metabolism of broilers

To investigate the effects of Clostridium butyricum (C. butyricum) on breast muscle lipid metabolism of broilers, 192 one-day-old male Arbor Acres broilers were randomly allocated into 2 treatments with 6 replicates in a completely randomised design. The broilers were fed corn-soybean meal-based diets and supplemented with 0 or 1 × 109 cfu of C. butyricum/kg of diet for 42 days. The birds in the C. butyricum-supplemented group showed higher (p < .05) average daily gain during the grower phase and throughout the entire period of the experiment and a lower (p = .047) feed conversion rate during the grower phase. Supplementation with C. butyricum increased (p < .05) the intramuscular fat content, lipoprotein lipase activity and mRNA levels in the breast muscle at 42 days of age, increased (p = .032) the serum insulin level at 21 days of age, and enhanced (p = .020) the caecal Firmicutes relative abundance at 42 days of age. Additionally, supplementation with C. butyricum reduced (p < .05) the serum growth hormone levels at both 21 and 42 days of age, decreased (p < .05) the ileum angiopoietin-like protein 4 (ANGPTL4) mRNA levels and serum ANGPTL4 concentrations at 42 days of age, and decreased (p < .05) the hormone-sensitive lipase activity, carnitine palmitoyltransferase 1, carnitine palmitoyltransferase 2, and long-chain acyl-CoA dehydrogenase mRNA levels in the breast muscle at 42 days of age. In conclusion, dietary supplementation with C. butyricum could potentially target caecal microbiota and reduced the breast muscle fatty acid oxidation of broilers

Effects of newly harvested corn on growth performance, intestine development and metabolism of nutrients in broilers

This experiment was to study the effects of newly harvested corn on growth performance, intestine development and metabolism of nutrients in broilers. A total of 380 one-day-old Arbor Acres male broilers were assigned to ageing corn group (AC group), 1/3 newly harvested corn group (1/3 NC group), 2/3 newly harvested corn group (2/3 NC group), and newly harvested corn group (NC group), which according to the proportion of newly harvested corn in the total amount of corn of basal diets. Each group included six replicates with 16 birds. Digestion and metabolism trials were conducted at 39 to 42 days of age. Results showed that feed: gain ratio (F/G) of NC group was higher than that of 1/3 NC group and 2/3 NC group at 22 to 42 and 1 to 42 days of age (p < .05). The metabolic rates of calcium and phosphorus in NC group were lower than those in AC group, 1/3 NC group and 2/3 NC group (p < .05). In NC group, the relative weight of caecum was significantly higher than that in 2/3 NC group and AC group at 21 days of age (p < .05), while the relative weight of jejunum was lower than that in 2/3 NC group and AC group at 42 days of age (p < .05). In summary, newly harvested corn can reduce the growth performance and metabolism of some nutrients in broilers. Newly harvested corn should be controlled during actual production.Highlights Newly harvested corn can reduce the growth performance in broilers. Newly harvested corn can reduce apparent metabolic rate of calcium and phosphorus in broilers. Newly harvested corn can affect the intestine development in broilers

Low-protein diets with balanced amino acids reduce nitrogen excretion and foot pad dermatitis without affecting the growth performance and meat quality of free-range yellow broilers

An experiment was conducted to evaluate the effects of crude protein (CP) levels on growth performance, carcase quality, meat quality, immune indices, litter and faeces quality, as well as welfare quality, in free-range yellow broilers using balanced amino acid technology. In total, 600 one-d-old Suqin yellow broilers were raised for 21 d. On d 22, 540 birds with similar BW (390 ± 7 g SD) were randomly selected and placed into 9 pens (3 groups with 3 replicates per group and 60 birds each replicate) and then reared to 56 d of age. The birds were fed a diet containing CP 19% (control), 18% or 17% (measured value: 18.878%, 17.881%, 17.052%, respectively), in three groups for 35 d. The results revealed that decreasing dietary CP levels from 19% to 17% had no impact on broiler growth performance, carcase quality and meat quality (p > .05). The relative immune organ weights also showed no change to the lowering of dietary CP levels (p > .05), whereas serum albumin was significantly influenced by decreasing dietary CP levels (p = .042). Furthermore, nitrogen content in litter and faeces, as well as the footpad dermatitis score for welfare indices, were decreased with decreased dietary CP levels (p = .009, p = .014, p = .045, respectively). The results of this study suggest that low-protein diets with balanced amino acids reduce nitrogen excretion and footpad dermatitis without effecting the performance, carcase quality, and meat quality of free-range yellow broilers