As grain prices have increased dramatically in the past year, understanding the fundamental genetic, cellular, and biochemical mechanisms responsible for feed efficiency (FE; g of gain/g of feed) or residual feed intake (RFI; an alternative feed efficiency trait that quantifies interanimal variation in DMI that is unexplained by differences in BW and growth rate) in livestock and poultry is extremely important with respect to maintaining viable meat production practices in the United States. Although breed and diet have long been known to affect mitochondrial function, few studies have investigated differences in mitochondrial function and biochemistry due to interanimal phenotypic differences in FE or RFI (i.e., variation among animals of the same breed and fed the same diet). This paper reviews existing literature on relationships of mitochondrial function and biochemistry with FE and RFI in poultry and livestock. The overall goal of all of this paper is to assist the development of tools (e.g., genetic markers or biomarkers) to aid commercial breeding companies in genetic selection that, in turn, will help maintain viable livestock and poultry industries in the United States and around the world. Copyright © 2009. . Copyright 2009 Journal of Animal Science

In this research a DNA aptamer, which was selected through SELEX (systematic evolution of ligands by exponential enrichment) to be specific against the H5N1 subtype of the avian influenza virus (AIV), was used as an alternative reagent to monoclonal antibodies in an impedance biosensor utilizing a microfluidics flow cell and an interdigitated microelectrode for the specific detection of H5N1 AIV. The gold surface of the interdigitated microelectrode embedded in a microfluidics flow cell was modified using streptavidin. The biotinylated aptamer against H5N1 was then immobilized on the electrode surface using biotin–streptavidin binding. The target virus was captured on the microelectrode surface, causing an increase in impedance magnitude. The aptasensor had a detection time of 30 min with a detection limit of 0.0128 hemagglutinin units (HAU). Scanning electron microscopy confirmed the binding of the target virus onto the electrode surface. The DNA aptamer was specific to H5N1 and had no cross-reaction to other subtypes of AIV (e.g., H1N1, H2N2, H7N2). The newly developed aptasensor offers a portable, rapid, low-cost alternative to current methods with the same sensitivity and specificity.

Studies have been conducted in our laboratory to assess differences in mitochondrial function and biochemistry in male broilers with high and low feed efficiency (FE) from the same genetic line and fed the same diet. Mitochondria obtained from broilers with low FE exhibited greater uncoupling of the electron transport chain (ETC) that was apparently due to site-specific defects in electron transport resulting in higher amounts of reactive oxygen species (ROS) compared with high FE mitochondria. Higher amounts of ROS production in Low FE mitochondria were likely responsible for higher protein carbonyl levels, indicative of higher protein oxidation compared with High FE mitochondria and tissue. In turn, higher protein damage in Low FE mitochondria may have contributed to lower activity of electron transport chain complexes relative to values observed in high FE mitochondria. Low FE mitochondria did not exhibit a compromised ability to carryout oxidative phosphorylation, and although there were differences in expression of certain electron transport chain proteins, there was nothing that would indicate that differences in coupling and respiratory chain activity could be due to a general decrease in protein expression between low and high FE mitochondria. The results of these studies provide insight into understanding cellular mechanisms associated with the phenotypic expression of feed efficiency in broilers.

Modern broiler chickens exhibit very rapid growth and high feed efficiency compared to unselected chicken breeds. The improved production efficiency in modern broiler chickens was achieved by the intensive genetic selection for meat production. This study was designed to investigate the genetic alterations accumulated in modern broiler breeder lines during selective breeding conducted over several decades. To identify genes important in determining muscle growth and feed efficiency in broilers, RNA sequencing (RNAseq) was conducted with breast muscle in modern pedigree male (PeM) broilers (n = 6 per group), and with an unselected foundation broiler line (Barred Plymouth Rock; BPR). The RNAseq analysis was carried out using Ilumina Hiseq (2 x 100 bp paired end read) and raw reads were assembled with the galgal4 reference chicken genome. With normalized RPM values, genes showing >10 average read counts were chosen and genes showing 1.3 fold change were considered as differentially expressed (DE) between PeM and BPR. DE genes were subjected to Ingenuity Pathway Analysis (IPA) for bioinformatic functional interpretation. The results indicate that 2,464 DE genes were identified in the comparison between PeM and BPR. Interestingly, the expression of genes encoding mitochondrial proteins in chicken are significantly biased towards the BPR group, suggesting a lowered mitochondrial content in PeM chicken muscles compared to BPR chicken. This result is inconsistent with more slow muscle fibers bearing a lower mitochondrial content in the PeM. The molecular, cellular and physiological functions of DE genes in the comparison between PeM and BPR include organismal injury, carbohydrate metabolism, cell growth/proliferation, and skeletal muscle system development, indicating that cellular mechanisms in modern broiler lines are tightly associated with rapid growth and differential muscle fiber contents compared to the unselected BPR line. Particularly, PDGF (platelet derived growth factor) signaling and NFE2L2 (nuclear factor, erythroid 2-like 2; also known as NRF2) mediated oxidative stress response pathways appear to be activated in modern broiler compared to the foundational BPR line. Upstream and network analyses revealed that the MSTN (myostatin) –FST (follistatin) interactions and inhibition of AR (androgen receptor) were predicted to be effective regulatory factors for DE genes in modern broiler line. PRKAG3 (protein kinase, AMP-activated, gamma 3 non-catalytic subunit) and LIPE (lipase E) are predicted as core regulatory factors for myogenic development, nutrient and lipid metabolism. The highly upregulated genes in PeM may represent phenotypes of subclinical myopathy commonly observed in the commercial broiler breast tissue, that can lead to muscle hardening, named as woody breast. By investigating global gene expression in a highly selected pedigree broiler line and a foundational breed (Barred Plymouth Rock), the results provide insight into cellular mechanisms that regulate muscle growth, fiber composition and feed efficiency.

Mitochondria are responsible for roughly 90% of the ATP produced in a cell. A consequence of aerobic metabolism is oxidative stress that results from

Escherichia coli O157:H7 is one of the leading bacterial pathogens causing foodborne illness. In this study, an impedance immunosensor based on the use of magnetic nanobeads and screen-printed interdigitated electrodes was developed for the rapid detection of E. coli O157:H7. Magnetic nanobeads coated with anti-E. coli antibody were mixed with an E. coli sample and used to isolate and concentrate the bacterial cells. The sample was suspended in redox probe solution and placed onto a screen-printed interdigitated electrode. A magnetic field was applied to concentrate the cells on the surface of the electrode and the impedance was measured. The impedance immunosensor could detect E. coli O157:H7 at a concentration of 10^4.45 cfu·mL⁻¹ (~1400 bacterial cells in the applied volume of 25 μL) in less than 1 h without pre-enrichment. A linear relationship between bacteria concentration and impedance value was obtained between 10⁴ cfu·mL⁻¹ and 10⁷ cfu·mL⁻¹. Though impedance measurement was carried out in the presence of a redox probe, analysis of the equivalent circuit model showed that the impedance change was primarily due to two elements: Double layer capacitance and resistance due to electrode surface roughness. The magnetic field and impedance were simulated using COMSOL Multiphysics software.