Effects of Dietary Amino Acid Density and Exogenous Protease Inclusion on Growth Performance and Apparent Ileal Amino Acid Digestibility in Turkeys

Protein is one of the most expensive nutrients in poultry diets. In an effort to minimize feed costs, protein digestion and utilization by the animal must be carried out as effi­ciently as possible. The objective of this experiment was to evaluate the effects of dietary amino acid density and exogenous protease inclusion on growth performance and amino acid digestibility in turkey poults. Hybrid turkey poults (n = 780) were fed diets formulated to provide low (LAA) or adequate (AAA) amino acid density (approxi­mately 91 and 100% of the NRC4 recommended requirement for digestible Lys, respec­tively) with each diet being fed with or without an exogenous protease. Poults received experimental diets from d 1 to 42 of age. Growth performance metrics were calculated from pen weights and feed consumption was recorded throughout each experiment, and digestibility data were obtained from analysis of ileal contents. Data were analyzed using SAS 9.4 with pen as the experimental unit and pen location as the blocking factor. For the overall experiment (d 0 to 42), poults fed AAA diets had improved (P \u3c 0.01) ADG, ADFI, and feed conversion ratio (FCR) compared to those fed LAA diets. There was no difference (P \u3e 0.14) in poult performance due to protease inclusion. There was an amino acid density × protease interaction (P = 0.01) for apparent ileal amino acid digestibility (AIAAD) of Trp. There was no difference in AIAAD coefficients of Trp in the LAA diets with or without protease. However, in the AAA diets, poults not receiving protease had greater AIAAD of Trp than those consuming protease. There was no difference (P \u3e 0.09) in AIAAD coefficients of Arg, Met, Cys, Thr, Ile, Leu, Lys, or Val due to dietary amino acid density or protease inclusion. Greater amino acid density improved growth performance in poults up to 42 d of age. No improvement in growth performance was observed when poults were fed an exogenous protease in the starter phase, although protease inclusion increased ADG by 5.3% and ADFI by 4.1% during the grower phase. There was no benefit of increased dietary amino acid density or protease inclusion on AIAAD in poults

Effects of Dietary Amino Acid Density and Exogenous Protease Inclusion on Growth Performance and Apparent Ileal AA Digestibility in Broilers

Protein is one of the most expensive nutrients in poultry diets. In an effort to minimize feed costs, protein digestion and utilization by the animal must be carried out as efficiently as possible. Therefore, the objective of this study was to evaluate the effects of dietary AA density and exogenous protease inclusion on growth performance and AA digestibility in broilers. Treatments consisted of a 2 × 4 factorial design with main effects of commercial protease (with or without) and digestible Lys (1.12, 1.15, 1.18, or 1.21%). Broiler chicks were housed in 4 Petersime batteries and treatments were randomly assigned to 80 cages within location block, resulting in 10 cages per treatment with 6 chicks per cage at placement. A commercial enzyme complex with 3 proteolytic activities was added to the protease diets at 0.25 lb/ton, and the same inclusion of sand was added to the diets without protease. Diets were balanced by energy and Lys:amino acid ratios. Titanium dioxide was included in the diets at 0.5% as an indigestible marker. On d 20, ileal contents from 2 chicks per cage were collected and composited by cage for calculation of apparent ileal AA digestibility. Growth performance metrics were calculated from cage weights and feed consumption was recorded throughout the experiment, and AA digestibility data were obtained from analysis of ileal contents. Data were analyzed using SAS 9.4 with cage as the experimental unit and cage location as the blocking factor. There was no evidence of an amino acid density × protease interaction (P \u3e 0.05) for BW, ADG or ADFI. There was an amino acid density × protease interaction (quadratic, P \u3c 0.05) for feed conversion ratio (FCR). Chicks fed 1.12 and 1.21% digestible Lys diets with added protease had a 2-point improvement in FCR compared to chicks fed these diets without protease. There was no difference in FCR between birds consuming diets with or without protease when fed 1.15 and 1.18% digestible Lys diets. There was no evidence of difference (P \u3e 0.10) in ADG or ADFI due to dietary amino acid density throughout the feeding period. However, broiler FCR was improved (linear, P \u3c 0.01) by increasing dietary amino acid density from 1.12 to 1.21% digestible Lys. There was no evidence (P \u3e 0.10) of main effect of added protease on BW, ADG, ADFI, or FCR. There was not an amino acid density × protease interaction (P \u3e 0.09) or main effect of dietary amino acid density or protease inclusion (P \u3e 0.12) on apparent ileal digestibility (AID) of Lys, Arg, Met, Cys, Thr, Ile, Leu, Val, or Trp. In conclusion, increasing dietary amino acid density improved FCR in broiler chicks, and the rate of improvement was dependent on the inclusion of an exogenous protease

Involvement of Noradrenergic Neurotransmission in the Stress- but not Cocaine-Induced Reinstatement of Extinguished Cocaine-Induced Conditioned Place Preference in Mice: Role for β-2 Adrenergic Receptors

The responsiveness of central noradrenergic systems to stressors and cocaine poses norepinephrine as a potential common mechanism through which drug re-exposure and stressful stimuli promote relapse. This study investigated the role of noradrenergic systems in the reinstatement of extinguished cocaine-induced conditioned place preference by cocaine and stress in male C57BL/6 mice. Cocaine- (15 mg/kg, i.p.) induced conditioned place preference was extinguished by repeated exposure to the apparatus in the absence of drug and reestablished by a cocaine challenge (15 mg/kg), exposure to a stressor (6-min forced swim (FS); 20–25°C water), or administration of the α-2 adrenergic receptor (AR) antagonists yohimbine (2 mg/kg, i.p.) or BRL44408 (5, 10 mg/kg, i.p.). To investigate the role of ARs, mice were administered the nonselective β-AR antagonist, propranolol (5, 10 mg/kg, i.p.), the α-1 AR antagonist, prazosin (1, 2 mg/kg, i.p.), or the α-2 AR agonist, clonidine (0.03, 0.3 mg/kg, i.p.) before reinstatement testing. Clonidine, prazosin, and propranolol failed to block cocaine-induced reinstatement. The low (0.03 mg/kg) but not high (0.3 mg/kg) clonidine dose fully blocked FS-induced reinstatement but not reinstatement by yohimbine. Propranolol, but not prazosin, blocked reinstatement by both yohimbine and FS, suggesting the involvement of β-ARs. The β-2 AR antagonist ICI-118551 (1 mg/kg, i.p.), but not the β-1 AR antagonist betaxolol (10 mg/kg, i.p.), also blocked FS-induced reinstatement. These findings suggest that stress-induced reinstatement requires noradrenergic signaling through β-2 ARs and that cocaine-induced reinstatement does not require AR activation, even though stimulation of central noradrenergic neurotransmission is sufficient to reinstate

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Do selective serotonin reuptake inhibitors acutely increase frontal cortex levels of serotonin?

Selective serotonin uptake inhibitors (SSRIs) exert their effects by inhibiting serotonin (5-HT) re-uptake. Although blockade occurs almost immediately, the neurochemical effects on 5-HT, as measured by in vivo microdialysis, have been a matter of considerable debate. In particular, literature reports yield conflicting neurochemical results in the rat frontal cortex. Thus, while some groups consistently find increases in extracellular 5-HT levels following acute SSRI administration, others reproducibly report an absence of these acute serotonergic effects. In an attempt to unravel this apparent discrepancy, we combined published literature with in-house microdialysis experiments. When we plotted the lateral stereotaxic coordinate of the dialysis probe against published reports on the acute effects of fluoxetine a clear correlation was revealed. Whereas pronounced increases in SSRI-induced 5-HT were observed when the dialysis probe was placed 0 to 1 mm from the midline, effects diminished when the lateral probe placement was greater than 3 mm from the midline. In-house microdialysis studies corroborated these reports. Overall, these results illustrate - for the first time - that the midline stereotaxic coordinate is critical for interpreting the acute serotonergic effects of SSRIs within the frontal cortex. Moreover, the common observation that the clinical efficacy of SSRIs is not evident following acute administration complements preclinical microdialysis results in the lateral frontal cortex. The significance of this observation, along with potential explanations for the disparate neurochernical findings in the medial versus lateral cortices, will be discussed. (C) 2007 Elsevier B.V. All rights reserved

TRPV1 Antagonists and Chronic Pain: Beyond Thermal Perception

In the last decade, considerable evidence as accumulated to support the development of Transient Receptor Potential Vanilloid 1 (TRPV1) antagonists for the treatment of various chronic pain conditions. Whereas there is a widely accepted rationale for the development of TRPV1 antagonists for the treatment of various inflammatory pain conditions, their development for indications of chronic pain, where conditions of tactical, mechanical and spontaneous pain predominate, is less clear. Preclinical localization and expression studies provide a firm foundation for the use of molecules targeting TRPV1 for conditions of bone pain, osteoarthritis and neuropathic pain. Selective TRPV1 antagonists weakly attenuate tactile and mechanical hypersensivity and are partially effective for behavioral and electrophysiological endpoints that incorporate aspects of spontaneous pain. While initial studies with TRPV1 antagonist in normal human subjects indicate a loss of warm thermal perception, clinical studies assessing allelic variants suggests that TRPV1 may mediate other sensory modalities under certain conditions. The focus of this review is to summarize the current perspectives of TRPV1 for the treatment of conditions beyond those with a primary thermal sensitivity

The effects of medium chain fatty acids in mash and pelleted diets on growth performance of broilers

The objective of this experiment was to determine the effects of medium chain fatty acids (MCFA) in mash and crumbled broiler diets. A total of 400 male chicks (Cobb 500; initial BW 41.8 g) were housed in 4 Petersime batteries and used in an 18-d study. Treatments were randomly assigned to 80 cages within location block resulting in 8 cages per treatment with 5 chicks per cage at placement. Treatments were arranged in a 2 × 5 factorial with main effects of feed type (mash and crumble) and 0.5% Medium Chain Fatty Acid inclusion (Control no inclusion; Hexanoic Acid (C6); Octanoic Acid (C8); Decanoic Acid (C10); Dodeanoic Acid (C12)). Fat inclusion in the diets were equalized using 0.5% soybean oil in the control diet. Feed was pelleted using a CPM (model CL5) pellet mill equipped with a 3.97×2.22 mm die. Feed was pelleted at a conditioning temperature and retention time of 85°C and 20 sec, respectively. Dietary treatments were fed for the full duration of the study. Data was analyzed as a randomized complete block design using the PROC MIXED procedure of SAS. Results were considered significant at P ≤ 0.05 and marginally significant between P > 0.05 and P ≤ 0.10. For d 0 to 12 and d 0 to 18, there were no feed form × MCFA interactions. From d 0 to 12, broilers fed crumbles had improved (P 0.10) on broiler performance. Pelleting and crumbling feed improved growth performance regardless of MCFA inclusion. MCFA inclusion did not positively influence growth performance