Low Feed Efficient Broilers Within a Single Genetic Line Exhibit Higher Oxidative Stress and Protein Expression in Breast Muscle with Lower Mitochondrial Complex Activity

Identification of single nucleotide polymorphisms (SNPs) potentially associated with residual feed intake in Qinchuan beef cattle by hypothalamus and duodenum RNA-Seq data

The regulation of residual feed intake (RFI) in beef cattle involves brain-gut mechanisms due to the interaction between neural signals in the brain and hunger or satiety in the gut. RNA-Seq data contain an extensive resource of untapped SNPs. Therefore, hypothalamic and duodenal tissues from ten extreme RFI individuals were collected, and transcriptome sequenced in this study. All the alignment data were combined according to RFI, and the SNPs in the same group were identified. A total of 270,410 SNPs were found in the high RFI group, and 255,120 SNPs were found in the low RFI group. Most SNPs were detected in the intronic region, followed by the intergenic region, and the exon region accounts for 1.11% and 1.38% in the high and low RFI groups, respectively. Prediction of high-impact SNPs and annotation of the genes in which they are located yielded 83 and 97 genes in the high-RFI and low-RFI groups, respectively. GO enrichment analysis of these genes revealed multiple NADH/NADPH-related pathways, with ND4, ND5, and ND6 significantly enriched as core subunits of NADH dehydrogenase (complex I), and is closely related to mitochondrial function. KEGG enrichment analysis of ND4, ND5, and ND6 genes was enriched in the thermogenic pathway. Multiple genes, such as ATP1A2, SLC9A4, and PLA2G5, were reported to be associated with RFI energy metabolism in the concurrent enrichment analysis. Protein-protein interaction analysis identified multiple potential candidate genes related to energy metabolism that were hypothesized to be potentially associated with the RFI phenotype. The results of this study will help to increase our understanding of identifying SNPs with significant genetic effects and their potential biological functions.

A high-resolution bovine mitochondrial co-expression network

The mitochondrion is a sophisticated, versatile, and dynamic organelle whose function is incompletely understood. Intending to provide a framework for mitochondrial visualisation and interpretation of genome-wide molecular data, we reverse-engineered a co-expression network whose final structure represented mRNA encoding more than half of the entire mitochondrial proteome. We drew upon 723 RNA-seq data sets representing 91 tissues and cell types from 441 individual cattle. A mitochondrial landscape was formed comprising a main network and many smaller sub-networks. One of the discrete sub-networks contains all 13 mRNA (e.g. MT-ND1, MT -CYTB, MT -COX2, MT -ATP8) plus 15/22 tRNA (e.g. MT-TT) encoded by the mt-genome itself, indicating some independent regulation from the nuclear genome with whom it must cooperate. Intriguingly, this mtDNA sub-network also contains a single nuclear-encoded gene, that of PDHA1. PDHA1 encodes a subunit of the pyruvate dehydrogenase complex that governs the conversion of pyruvate to Acetyl CoA. This enzyme is extremely influential, representing the fundamental cellular connection between the ancient, conserved pathway of glycolysis that occurs exclusively in the cytoplasm, and the TCA cycle that occurs within the mitochondrial matrix. To demonstrate the downstream utility of our approach, we overlaid Longissimus dorsi muscle transcriptome data from differentially feed efficient Charolais and Holstein Friesian cattle. This approach highlighted expression patterns sensitive to both breed and diet in a complex manner. An analytic advantage of this approach is that relatively subtle (<2-fold) but coordinated changes that may be overlooked by conventional gene-by-gene significance testing become readily apparent. Finally, intending to understand the transcriptional regulation of mitochondrial function more thoroughly, we engineered a network built with transcription factors in addition to those mRNA encoding mitochondrial proteins. Here, a set of influential nuclear hormone receptors (e.g. PPARA) are enriched among the most highly and/or well-connected TF.

Dietary ferulic acid improves growth performance of broilers via enhanced intestinal antioxidant capacity and barrier function

OBJECTIVE

In this study, the effects of dietary ferulic acid (FA) on the growth traits, antioxidant capacity, and intestinal barrier function of broilers were investigated.

METHODS

In total, 192 male Arbor Acres broilers were randomly allocated to one of three dietary groups (8 replicates of 8 birds each): control (CON) group (basal diet), FA100 group (basal diet + 100 mg/kg FA), or FA200 group (basal diet + 200 mg/kg FA). The duration of the feeding trial was 42 days.

RESULTS

Higher average daily gain (ADG) and lower feed to gain (F/G) ratio during day 0 to day 21 were found in the FA100 and FA200 groups, while higher ADG and lower F/G during day 21 to day 42 were only found in FA200 group, compared to the CON group (p<0.05). Serum levels of malondialdehyde and diamine oxidase on day 21 were lower in the FA100 and FA200 groups and those on day 42 were lower in the FA200 group, while glutathione peroxidase level in the FA100 and FA200 groups on day 21 and that in the FA200 group on day 42 were increased (p<0.05). On day 21, jejunal glutathione synthetase (GSS) expression was upregulated in the FA200 group (p<0.05), while jejunal and ileal expression of nuclear factor erythroid 2-related factor 2 (NRF2) and Occludin as well as ileal expression of glutathione peroxidase 1 (GPX1) and zonula occludens 1 (ZO1) were increased in the FA100 and FA200 groups compared to the CON group (p<0.05). On day 42, mRNA expression of GSS, NRF2, SOD1, and GPX1 in the jejunum and ileum as well as Claudin2 in the jejunum and Occludin in the ileum were increased in the FA200 group (p<0.05).

CONCLUSION

Dietary FA addition could improve the growth performance, antioxidant capacity, and gut integrity of broilers. The current findings provided evidence that the adoption of FA can be a nutrition intervention measure to achieve high-efficient broiler production for poultry farmers.

OMICs approaches and technologies for understanding low-high feed efficiency traits in chicken: implication to breeding

In poultry production, there has been a trend of continuous increase in cost of feed ingredients which represents the major proportion of the production costs. Feed costs can be reduced by improving feed efficiency traits which increase the possibility of using various indigestible feed sources and decrease the environmental impact of the enhanced poultry production. Therefore, feed efficiency has been used as one of the most important economic traits of selection in the breeding program of chickens. Recently, many OMICs experimental studies have been designed to characterize biological differences between the high and low feed efficiency chicken phenotypes. Biological complexity cannot be fully captured by main individual OMICs such as genomics, transcriptomics, proteomics and metabolomics. Therefore, researchers have combined multiple assays from the same set of samples to create multi-OMICs datasets. OMICs findings are crucial in improving existing approaches to poultry breeding. The current review aimed to highlight the components of feed efficiency and general OMICs approaches and technologies. Besides, individual and multi-OMICs based understanding of chicken feed efficiency traits and the application of the acquired knowledge in the chicken breeding program were addressed.

Reduced PGC-1β protein expression may underlie corticosterone inhibition of mitochondrial biogenesis and oxidative phosphorylation in chicken muscles

To uncover the molecular mechanism underlying glucocorticoid-induced loss of mitochondrial integrity in skeletal muscles, studies were performed to investigate whether the peroxisome proliferator-activated receptor γ coactivator 1 (PGC-1)-mediated pathway was involved in this process. In an in vivo trial, 3 groups of 30-d-old Arbor Acres male broilers were randomly subjected to one of the following treatments for 7 days: corticosterone (CORT, 30 mg/kg diet), control (blank), and pair-feeding (restricted to the same feed intake as for the CORT treatment), each with 6 replicates of 15 birds. Mitochondrial abundance, morphology, and function were determined in the pectoralis major and biceps femoris muscles. In an in vitro trial, a primary culture of embryonic chick myotubes was incubated with a serum-free medium for 24 h in the presence or absence of CORT (0, 200, and 1,000 nM). Results showed that CORT destroyed mitochondrial ultrastructure (p < 0.01), and decreased the enzymatic activity and protein expression of respiratory chain complexes (p < 0.05), leading to an inferior coupling efficiency (p < 0.05). As reflected by a decline in mitochondrial density (p < 0.01) and mitochondrial DNA copy number (p < 0.05), CORT reduced mitochondrial contents. Among all three PGC-1 family members, only PGC-1β was down-regulated by CORT at the protein level (p < 0.05). Some aspects of these responses were tissue-specific and seemed to result from the depressed feed intake. Overall, CORT may impair mitochondrial biogenesis and oxidative phosphorylation in a PGC-1β-dependent manner in chicken muscles.

Proteomic analysis of adipose tissue revealing differentially abundant proteins in highly efficient mid-lactating dairy cows

The improvement of nutrient utilization efficiency in dairy cows represents an important task in view of the current rising demand for animal products and sustainable resource usage. In this perspective, the identification of appropriate markers to identify the most efficient animals for dairy production becomes a crucial factor. Residual feed intake (RFI), which represents the difference between predicted and actual intake, is used to define the efficiency of cows. In this study, subcutaneous adipose tissue (AT) was collected from five high efficient (HEF) and five low efficient (LEF) mid-lactation Holstein dairy cows, that represented subgroups of the 20% lowest RFI values (HEF) and highest 20% RFI values (LEF), out of a cohort of 155 cows that were examined for feed efficiency at the individual dairy barn at Volcani Institute, Israel. Adipose samples were examined for proteomic analysis by nano-LC/MS–MS and gene expression by RT-PCR. A total of 101 differential proteins (P ≤ 0.05 and fold change ± 1.5) and two protein networks related to feed efficiency were found between HEF and LEF cows. Among the enriched top canonical pathways, FAT10 signaling, EIF2 signaling, Sirtuin signaling, Acute phase response signaling, Protein ubiquitination and mTOR signaling pathways were related to feed efficiency in AT. Furthermore, abundance of transferrin (TF; FC = 78.35, P = 0.02) enriched pathways, including mTOR signaling, LXR/RXR and FXR/RXR activation was found in AT of HEF cows. Relative mRNA expression of RBM39, which is involved in energy metabolism, was decreased in AT of HEF versus LEF. The relationship found between the AT proteins and/or metabolic pathways and the feed efficiency demonstrates that AT may reflect metabolic adaptations to high efficiency, and suggests that these proteins together with their metabolic mechanisms are suitable candidates as biomarkers to identify efficient cows for dairy production.

Proper Immune Response Depends on Early Exposure to Gut Microbiota in Broiler Chicks

The successional changes in the early intestinal microbiota occur concomitantly with the development, expansion, and education of the mucosal immune system. Although great attention of researchers has been focused on understanding the linkage between microbiota and immune functions, many essential details of the symbiotic relationship between the intestinal pioneer microbiota and the avian immune system remain to be discovered. This study was conducted to understand the impact of different early life intestinal colonizers on innate and adaptive immune processes in chicks and further identify immune-associated proteins expressed in the intestinal tissue. To accomplish it, we performed an in ovo application of two apathogenic Enterobacteriaceae isolates and lactic acid bacteria (L) to determine their influences on the intestinal proteome profile of broilers at the day of hatch (DOH) and at 10 days old. The results indicated that there were predicted biological functions of L-treated chicks associated with the activation and balanced function of the innate and adaptive immune systems. At the same time, the Enterobacteriaceae-exposed birds presented dysregulated immunological mechanisms or downregulated processes related to immune development. Those findings suggested that a proper immune function was dependent on specific gut microbiota exposure, in which the prenatal probiotic application may have favored the fitting programming of immune functions in chicks.

Corn Silage Supplemented with Pomegranate (Punica granatum) and Avocado (Persea americana) Pulp and Seed Wastes for Improvement of Meat Characteristics in Poultry Production

In the present study, pomegranate peels, avocado peels, and seed vacuum microwave extraction solid by-products were supplemented in corn silage in order to investigate the effects on meat quality and growth rate in broiler chicken. There were 50 broilers, divided in two groups, treated with experimental or usual feed for 43 days (group A: 25 broilers fed with avocado and pomegranate by-products and group B: 25 broilers fed with corn-silage used as control). The results showed that broiler chickens fed with a diet supplemented with a mixture of pomegranate avocado by-products (group A) showed significant differences in chicken leg meat quality, significantly improving the level of proteins and fatty acids content in breast and leg meat, respectively. More specific ω3 and ω6 fatty acids content were three times higher than in group B. Moreover, a protective effect on the decomposition of polyunsaturated fatty acids, induced by free radicals and presented in chicken meat, is based on the evaluation of lipid peroxidation by measuring thiobarbituric acid reactive substances. Pomegranate peels, avocado peels, and seed by-products appeared to have a slight reduction on meat production, while it was found to improve the qualitative chicken meat characteristics. Regarding the production costs, it was calculated that the corn-silage supplementation, used in this study, lead to a 50% lower cost than the commercial corn-silage used for the breeding of broilers.

Lawsonia intracellularis infected enterocytes lack sucrase-isomaltase which contributes to reduced pig digestive capacity

Lawsonia intracellularis is endemic to swine herds worldwide, however much is still unknown regarding its impact on intestinal function. Thus, this study aimed to characterize the impact of L. intracellularis on digestive function, and how vaccination mitigates these impacts. Thirty-six L. intracellularis negative barrows were assigned to treatment groups (n  =  12/trt): (1) nonvaccinated, L. intracellularis negative (NC); (2) nonvaccinated, L intracellularis challenged (PC); and (3) L. intracellularis challenged, vaccinated (Enterisol^® Ileitis, Boehringer Ingelheim) 7 weeks pre-challenge (VAC). On days post-inoculation (dpi) 0 PC and VAC pigs were inoculated with L. intracellularis. From dpi 19–21 fecal samples were collected for apparent total tract digestibility (ATTD) and at dpi 21, pigs were euthanized for sample collection. Post-inoculation, ADG was reduced in PC pigs compared with NC (41%, P  <  0.001) and VAC (25%, P  <  0.001) pigs. Ileal gross lesion severity was greater in PC pigs compared with NC (P  =  0.003) and VAC (P  =  0.018) pigs. Dry matter, organic matter, nitrogen, and energy ATTD were reduced in PC pigs compared with NC pigs (P  ≤  0.001 for all). RNAscope in situ hybridization revealed abolition of sucrase-isomaltase transcript in the ileum of PC pigs compared with NC and VAC pigs (P  <  0.01). Conversely, abundance of stem cell signaling markers Wnt3, Hes1, and p27^Kip1 were increased in PC pigs compared with NC pigs (P  ≤  0.085). Taken together, these data demonstrate that reduced digestibility during L. intracellularis challenge is partially driven by abolition of digestive machinery in lesioned tissue. Further, vaccination mitigated several of these effects, likely from lower bacterial burden and reduced disease severity.

An examination of skeletal muscle and hepatic tissue transcriptomes from beef cattle divergent for residual feed intake

The selection of cattle with enhanced feed efficiency is of importance with regard to reducing feed costs in the beef industry. Global transcriptome profiling was undertaken on liver and skeletal muscle biopsies from Simmental heifers and bulls divergent for residual feed intake (RFI), a widely acknowledged feed efficiency phenotype, in order to identify genes that may be associated with this trait. We identified 5 genes (adj. p < 0.1) to be differentially expressed in skeletal muscle between high and low RFI heifers with all transcripts involved in oxidative phosphorylation and mitochondrial homeostasis. A total of 11 genes (adj. p < 0. 1) were differentially expressed in liver tissue between high and low RFI bulls with differentially expressed genes related to amino and nucleotide metabolism as well as endoplasmic reticulum protein processing. No genes were identified as differentially expressed in either heifer liver or bull muscle analyses. Results from this study show that the molecular control of RFI in young cattle is modified according to gender, which may be attributable to differences in physiological maturity between heifers and bulls of the same age. Despite this we have highlighted a number of genes that may hold potential as molecular biomarkers for RFI cattle.

The significant influence of residual feed intake on flavor precursors and biomolecules in slow-growing Korat chicken meat

Objective

This study investigated the association between feed efficiency, physicochemical properties, flavor precursors and biomolecules in the thigh meat of Korat (KR) chickens.

Methods

The feed intake and body weight of individual male KR chickens were recorded from 1 to 10 weeks old to calculate the individual residual feed intake (RFI) of 75 birds. At 10 weeks of age, chickens with the 10 highest (HRFI) and lowest RFI (LRFI) were slaughtered to provide thigh meat samples. The physicochemical properties (ultimate pH, water holding capacity [WHC], drip loss) and flavor precursors (guanosine monophosphate, inosine monophosphate (IMP), adenosine monophosphate and inosine) were analyzed conventionally, and Fourier transform infrared spectroscopy was used to identify the composition of biomolecules (lipids, ester lipids, amide I, amide II, amide III, and carbohydrates) and the secondary structure of the proteins. A group t-test was used to determine significant differences between mean values and principal component analysis to classify thigh meat samples into LRFI and HRFI KR chickens.

Results

The physicochemical properties of thigh meat samples from LRFI and HRFI KR chickens were not significantly different but the IMP content, ratios of lipid, lipid ester, protein (amide I, amide II) were significantly different (p<0.05). The correlation loading results showed that the LRFI group was correlated with high ratios of lipids, lipid esters, collagen content (amide III) and beta sheet protein (rg loading >0.5) while the HRFI group was positively correlated with protein (amide I, amide II), alpha helix protein, IMP content, carbohydrate, ultimate pH and WHC (rg loading >0.5).

Conclusion

The thigh meat from chickens with different RFI differed in physiochemical properties affecting meat texture, and in the contents of flavor precursors and biomolecules affecting the nutritional value of meat. This information can help animal breeders to make genetic improvements by taking more account of traits related to RFI.

Radical Response: Effects of Heat Stress-Induced Oxidative Stress on Lipid Metabolism in the Avian Liver

Lipid metabolism in avian species places unique demands on the liver in comparison to most mammals. The avian liver synthesizes the vast majority of fatty acids that provide energy and support cell membrane synthesis throughout the bird. Egg production intensifies demands to the liver as hepatic lipids are needed to create the yolk. The enzymatic reactions that underlie de novo lipogenesis are energetically demanding and require a precise balance of vitamins and cofactors to proceed efficiently. External stressors such as overnutrition or nutrient deficiency can disrupt this balance and compromise the liver’s ability to support metabolic needs. Heat stress is an increasingly prevalent environmental factor that impairs lipid metabolism in the avian liver. The effects of heat stress-induced oxidative stress on hepatic lipid metabolism are of particular concern in modern commercial chickens due to the threat to global poultry production. Chickens are highly vulnerable to heat stress because of their limited capacity to dissipate heat, high metabolic activity, high internal body temperature, and narrow zone of thermal tolerance. Modern lines of both broiler (meat-type) and layer (egg-type) chickens are especially sensitive to heat stress because of the high rates of mitochondrial metabolism. While this oxidative metabolism supports growth and egg production, it also yields oxidative stress that can damage mitochondria, cellular membranes and proteins, making the birds more vulnerable to other stressors in the environment. Studies to date indicate that oxidative and heat stress interact to disrupt hepatic lipid metabolism and compromise performance and well-being in both broilers and layers. The purpose of this review is to summarize the impact of heat stress-induced oxidative stress on lipid metabolism in the avian liver. Recent advances that shed light on molecular mechanisms and potential nutritional/managerial strategies to counteract the negative effects of heat stress-induced oxidative stress to the avian liver are also integrated.

Brachyspira hyodysenteriae Infection Reduces Digestive Function but Not Intestinal Integrity in Growing Pigs While Disease Onset Can Be Mitigated by Reducing Insoluble Fiber

Swine dysentery (SD) induced by Brachyspira hyodysenteriae manifests as mucohemorrhagic diarrhea in pigs, but little is known about the changes that occur to the gastrointestinal tract during this disease. It is thought that dietary fibers alter disease pathogenesis, although the mechanisms of action are unclear. Thus, the objectives of this study were to characterize intestinal integrity, metabolism, and function in pigs during SD and determine if replacing insoluble fiber with fermentable fibers mitigates disease. Thirty-six B. hyodysenteriae-negative gilts [24.3 ± 3.6 kg body weight (BW)] were assigned to one of three treatment groups: (1) B. hyodysenteriae negative, control diet (NC); (2) B. hyodysenteriae challenged, control diet (PC); and (3) B. hyodysenteriae challenged, highly fermentable fiber diet (RS). The NC and PC pigs were fed the same control diet, containing 20% corn distillers dried grains with solubles (DDGS). The RS pigs were fed a diet formulated with 5% sugar beet pulp and 5% resistant potato starch. On days post inoculation (dpi) 0 and 1, pigs were inoculated with B. hyodysenteriae or sham. Pigs were euthanized for sample collection after onset of SD. The challenge had high morbidity, with 100% of PC and 75% of RS pigs developing clinical SD. The timing of onset of clinical SD differed due to treatment, with RS pigs having a delayed onset (dpi 9) of clinical SD compared with dpi 7 for PC pigs. Colon transepithelial resistance was increased and macromolecule permeability was reduced in PC pigs compared with NC pigs (P < 0.01). Minimal changes in ileal permeability, mitochondrial function, or volatile fatty acids (VFAs) were observed. Total VFA concentrations were lower in the colon and cecum in both PC and RS pigs compared to NC pigs (both P < 0.05), but iso-acids were higher (both P < 0.05). Total tract digestibility of dry matter (DM), organic matter (OM), nitrogen (N), and gross energy (GE) was lower in PC pigs compared with both NC and RS pigs (both P < 0.001). These data indicate that SD reduces digestive function but does not reduce ex vivo intestinal integrity. Further, replacement of insoluble fiber with highly fermentable fibers mitigated and delayed the onset of SD.

Differences in Breast Muscle Mitochondrial Respiratory Capacity, Reactive Oxygen Species Generation, and Complex Characteristics between 7-week-old Meat- and Laying-type Chickens

The skeletal muscle growth rate is a major feature differentiating meat- and laying-type chickens. A large amount of ATP is required during skeletal muscle synthesis, in which mitochondrial energy production capacities play a significant role. Additionally, mitochondria may participate in muscle protein degradation via reactive oxygen species generation. To investigate the differences in mitochondrial energetic characteristics between chickens exhibiting different growth rates, this study evaluated respiratory capacities in response to different types of respiratory substrate, protein abundances, assembly of individual respiratory complexes (I-V) and supercomplexes, and reactive oxygen species generation rates. These characteristics were compared between mitochondria from the breast muscle (M. pectoralis superficialis) of seven-week-old meat- and laying-type male chickens. Blue native polyacrylamide gel electrophoresis analysis revealed that meat-type chickens exhibited a significantly lower protein abundance of complex III (cytochrome bc ₁ complex), complex V (F₀F₁ ATP synthase), and total amount of supercomplexes than did laying-type chickens. There were no differences between chicken types in the respiration rate of mitochondria incubated with either pyruvate/malate or succinate, each of which drives complex I- and complex II-linked respiration. Carnitine palmitoyltransferase-1-dependent and -independent respiration during ATP synthesis and carnitine palmitoyltransferase-2 enzymatic activity were significantly lower in meat-type chickens than in layingtype chickens. For mitochondria receiving pyruvate/malate plus succinate, the reactive oxygen species generation rate and its ratio to the oxygen consumed (the percentage of free radical leak) were also significantly lower in meat-type chickens than in laying-type chickens. These results suggested that the mitochondrial energetic capacities of the breast muscle of meat-type chickens could be lower than those of laying-type chickens at seven weeks of age. Furthermore, the lower reactive oxygen species generation rate in meat-type chickens might have implications for rapid muscle development, which is possibly related to their lower muscle protein degradation rates.

Effect of supplementing a Saccharomyces cerevisiae fermentation product during a preconditioning period prior to transit on receiving period performance, nutrient digestibility, and antioxidant defense by beef steers

Forty-eight newly weaned crossbred beef steers from a single-source were used to determine the effects of feeding a Saccharomyces cerevisiae fermentation product (SCFP; NaturSafe, Diamond V) on receiving period performance, nutrient digestibility, and antioxidant defense. Seven days after arrival, steers were stratified by BW (257 ± 18 kg), sorted into pens (n = 1 pen/treatment), and pens assigned to dietary treatments: SCFP at 0 (CON), 12 (SCFP12), 18 (SCFP18), or 0 g·steer^-1·d^-1 during preconditioning (PRE; days -19 to 0), then 18 g·steer^-1·d^-1 during receiving (REC; days 0 to 58; CON18). On day -1 BW and blood were collected, steers were loaded onto a semitruck and transported 1,748 km over 19 h. Upon return, steers were weighed, stratified by BW within treatment and sorted into pens with GrowSafe bunks (n = 12 steers/treatment). Steers were weighed on days -1, 0, 29, 30, 57, and 58. Blood was collected from all steers on days -1, 1, and 8 and liver biopsies were performed on all steers on days -20, -3, and 59. Titanium dioxide was included as an indigestible marker in the diet of all steers from days 14 through 29 to determine total tract nutrient digestibility. Data were analyzed as a completely randomized design using ProcMixed of SAS with the fixed effect of treatment. Steer was the experimental unit for REC period variables. Contrast statements compared the linear and quadratic effects of feeding SCFP throughout the trial (CON, SCFP12, and SCFP18) and the effect of supplementation at 18 g·steer^-1·d^-1 for the entire trial or starting in REC (SCFP18 vs. CON18). Steers fed SCFP12 exhibited the greatest ADG and G:F from days 0 to 30 (quadratic P ≤ 0.04). Total tract digestibility of NDF and ADF was linearly decreased by SCFP (linear P ≤ 0.03). On day -3, SCFP12-fed steers tended to have the greatest liver concentrations of total, oxidized, and reduced glutathione (quadratic P = 0.06). Red blood cell lysate Mn:total-superoxide dismutase activity was 16% greater 1 d posttransit compared with pretransit values (day P ≤ 0.01). Timing of SCFP supplementation (SCFP18 vs. CON18) did not affect any of the variables assessed herein (P ≥ 0.19). Supplementing SCFP at 12 g·steer^-1·d^-1 tended to affect antioxidant capacity prior to transit and improved early receiving period performance; however, overall receiving period performance was not affected by SCFP supplementation. Further research is necessary to determine the optimal dose and timing of SCFP supplementation for beef cattle.

Mitochondrial abundance and function in skeletal muscle and liver from Simmental beef cattle divergent for residual feed intake

Cellular mitochondrial function has been suggested to contribute to variation in feed efficiency (FE) among animals. The objective of this study was to determine mitochondrial abundance and activities of various mitochondrial respiratory chain complexes (complex I (CI) to complex IV (CIV)) in liver and muscle tissue from beef cattle phenotypically divergent for residual feed intake (RFI), a measure of FE. Individual DM intake (DMI) and growth were measured in purebred Simmental heifers (n = 24) and bulls (n = 28) with an initial mean BW (SD) of 372 kg (39.6) and 387 kg (50.6), respectively. All animals were offered concentrates ad libitum and 3 kg of grass silage daily, and feed intake was recorded for 70 days. Residuals of the regression of DMI on average daily gain (ADG), mid-test BW0.75 and backfat (BF), using all animals, were used to compute individual RFI coefficients. Animals were ranked within sex, by RFI into high (inefficient; top third of the population), medium (middle third of population) and low (efficient; bottom third of the population) terciles. Statistical analysis was carried out using the MIXED procedure of SAS v 9.3. Overall mean ADG (SD) and daily DMI (SD) for heifers were 1.2 (0.4) and 9.1 (0.5) kg, respectively, and for bulls were 1.8 (0.3) and 9.5 (1.02) kg, respectively. Heifers and bulls ranked as high RFI consumed 10% and 15% more (P < 0.05), respectively, than their low RFI counterparts. There was no effect of RFI on mitochondrial abundance in either liver or muscle (P > 0.05). An RFI × sex interaction was apparent for CI activity in muscle. High RFI animals had an increased activity (P < 0.05) of CIV in liver tissue compared to their low RFI counterparts; however, the relevance of that observation is not clear. Our data provide no clear evidence that cellular mitochondrial function within either skeletal muscle or hepatic tissue has an appreciable contributory role to overall variation in FE among beef cattle.

A Proteomic View of the Cross-Talk Between Early Intestinal Microbiota and Poultry Immune System

Proteomics has been used to investigate cross-talk between the intestinal microbiome and host biological processes. In this study, an in ovo technique and a proteomics approach was used to address how early bacterial colonization in the gastrointestinal tract (GIT) could modulate inflammatory and immune responses in young broilers. Embryos at 18 embryogenic days were inoculated with saline (S), 102 CFU of Citrobacter freundii (CF), Citrobacter species (C2), or lactic acid bacteria mixture (L) into the amnion. At 10 days posthatch, ileum samples from 12 birds per treatment were selected for tandem mass spectrometry analysis. Our further findings indicated that treatment-specific influences on early GIT microbiota resulted in different immune responses in mature broilers. Predicted functional analyses revealed activation of inflammation pathways in broilers treated in ovo with L and CF. Exposure to L enhanced functional annotation related to activation, trafficking of immune cells, and skeletal growth based-network, while CF inhibited biological functions associated with immune cell migration and inflammatory response. These results highlighted that proper immune function was dependent on specific GIT microbiota profiles, in which early-life exposure to L-based probiotic may have modulated the immune functions, whereas neonatal colonization of Enterobacteriaceae strains may have led to immune dysregulation associated with chronic inflammation.

Impact of in ovo administered pioneer colonizers on intestinal proteome on day of hatch

Pioneer colonization of the gastrointestinal tract (GIT) by bacteria is thought to have major influence on neonatal tissue development. Previous studies have shown in ovo inoculation of embryos with saline (S), species of Citrobacter (C, C2), or lactic acid bacteria (L) resulted in an altered microbiome on day of the hatch (DOH). The present study investigated GIT proteomic changes at DOH in relation to different inoculations. Embryos were inoculated in ovo with S or ∼10² cfu of C, C2, or L at 18 embryonic days. On DOH, the GIT was collected, and tissue proteins were extracted for analysis via tandem mass spectrometry. A total of 493 proteins were identified for differential comparison with S at P ≤ 0.10. Different levels were noted in 107, 39, and 78 proteins in C, C2, and L groups, respectively, which were uploaded to Ingenuity Pathway Analysis to determine canonical pathways and biological functions related to these changes. Three members of the cytokine family (interleukin [IL]-1β, IL6, and Oncostatin M) were predicted to be activated in C2, indicated with Z-score ≥ 1.50, which suggested an overall proinflammatory GIT condition. This was consistent with the activation of the acute-phase response signaling pathway seen exclusively in C2 (Z-score = 2.00, P < 0.01). However, activation (Z-score = 2.00) of IL-13, upregulation of peroxiredoxin-1 and superoxide dismutase 1, in addition to activation of nitric oxide signaling in the cardiovascular system of the L treatment may predict a state of increased antioxidant capacity and decreased inflammatory status. The nuclear factor erythroid 2-related factor 2 (NRF2)-mediated oxidative stress response (Z-score = 2.00, P < 0.01) was predicted to be upregulated in C which suggested that chicks were in an inflammatory state and associated oxidative stress, but the impact of these pathways differed from that of C2. These changes in the proteome suggest that pioneer colonizing microbiota may have a strong impact on pathways associated with GIT immune and cellular development.

Combination of herbal components (curcumin, carvacrol, thymol, cinnamaldehyde) in broiler chicken feed: Impacts on response parameters, performance, fatty acid profiles, meat quality and control of coccidia and bacteria

The objective of this study was to determine whether curcumin and a commercial microencapsulated phytogenic supplement containing thymol, cinnamaldehyde and carvacrol in broiler chicken feed would improve health and meat quality (fatty acid profile), as well as to determine the coccidiostatic and bactericidal potential of the additives. The broiler chickens were divided into five groups: NC - negative control feed; PC - positive control; CU - with 50 mg/kg of curcumin, PHY - 100 mg/kg phytogenic; and PHY + CU, a combination of both additives at 50 mg/kg (curcumin) and 100 mg/kg (phytogenic). We observed significantly higher levels of total proteins associated with increased circulating globulins, as well as lower levels of uric acid, cholesterol and triglycerides in the PHY + CU group than in the NC. There were significantly fewer oocysts in birds supplemented with additives in the NC group on day 21; on day 35, the NC, PHY and PHY + CU groups had significantly lower counts than the PC and CU groups; however, at 44 days, the lowest counts were in PC group. The bacterial counts were significantly lower on day 21 in all groups that received additives than those of the control group; however, at 44 days, the bacterial and Escherichia coli counts in these groups were significantly higher than those of the control. Curcumin with or without phytogenic agent improved meat quality, with increased antioxidant levels and reduction of lipid peroxidation. There were significantly lower total saturated fatty acid levels and significantly greater monounsaturated/polyunsaturated fatty acid levels in broilers that consumed additives individually and in combination. The combination of additives significantly increased the crypt/villus ratio, a marker of improved intestinal health and performance. Additives potentiated their individual effects, suggesting they can replace conventional growth promoters without compromising health, intestinal mucosa or meat quality.

BOARD INVITED REVIEW: Oxidative stress and efficiency: the tightrope act of mitochondria in health and disease1,2

Oxidative stress is an unavoidable consequence of aerobic metabolism. Whereas high amounts of mitochondrial reactive oxygen species (ROS) can cause oxidation, low levels play important roles in signal transduction. In a Pedigree male (PedM) broiler model of feed efficiency (FE), the low FE phenotype was characterized by increased ROS in isolated mitochondria (muscle, liver, and duodenum) with a pervasive protein oxidation in mitochondria and tissues. Subsequent proteogenomic studies in muscle revealed evidence of enhanced mitoproteome abundance, enhanced mitochondrial phosphocreatine shuttling expression, and enhanced ribosome assembly in the high FE phenotype. Surprisingly, an enhanced infrastructure would foster greater repair of damaged proteins or organelles through the autophagy and proteosome pathways in the high FE phenotype. Although protein and organelle degradation, recycling, and reconstruction would be energetically expensive, it is possible that energy invested into maintaining optimal function of proteins and organelles contributes to cellular efficiency in the high FE phenotype. New findings in mitochondrial physiology have been reported in the last several years. Reverse electron transport (RET), once considered an artifact of in vitro conditions, now is recognized to play significant roles in inflammation, ischemia-reperfusion, muscle differentiation, and energy utilization. A topology of ROS production indicates that ROS derived from Complex I of the respiratory chain primarily causes oxidation, whereas ROS generated from Complex III are primarily involved in cell signaling. It is also apparent that there is a constant fission and fusion process that mitochondria undergo that help maintain optimal mitochondrial function and enables mitochondria to adjust to periods of nutrient limitation and nutrient excess. Understanding the balancing act that mitochondria play in health and disease will continue to be a vital biological component in health-production efficiency and disease in commercial animal agriculture.

Impact of porcine reproductive and respiratory syndrome virus on muscle metabolism of growing pigs1

Porcine reproductive and respiratory syndrome (PRRS) virus is one of the most economically significant pig pathogens worldwide. However, the metabolic explanation for reductions in tissue accretion observed in growing pigs remains poorly defined. Additionally, PRRS virus challenge is often accompanied by reduced feed intake, making it difficult to discern which effects are virus vs. feed intake driven. To account for this, a pair-fed model was employed to examine the effects of PRRS challenge and nutrient restriction on skeletal muscle and liver metabolism. Forty-eight pigs were randomly selected (13.1 ± 1.97 kg BW) and allotted to 1 of 3 treatments (n = 16 pigs/treatment): 1) PRRS naïve, ad libitum fed (Ad), 2) PRRS-inoculated, ad libitum fed (PRRS+), and 3) PRRS naïve, pair-fed to the PRRS-inoculated pigs' daily feed intake (PF). At days postinoculation (dpi) 10 and 17, 8 pigs per treatment were euthanized and tissues collected. Tissues were assayed for markers of proteolysis (LM only), protein synthesis (LM only), oxidative stress (LM only), gluconeogenesis (liver), and glycogen concentrations (LM and liver). Growth performance, feed intake, and feed efficiency were all reduced in both PRRS+ and PF pigs compared with Ad pigs (P < 0.001). Furthermore, growth performance and feed efficiency were additionally reduced in PRRS+ pigs compared with PF pigs (P < 0.05). Activity of most markers of LM proteolysis (μ-calpain, 20S proteasome, and caspase 3/7) was not increased (P > 0.10) in PRRS+ pigs compared with Ad pigs, although activity of m-calpain was increased in PRRS+ pigs compared with Ad pigs (P = 0.025) at dpi 17. Muscle reactive oxygen species production was not increased (P > 0.10) in PRRS+ pigs compared with Ad pigs. However, phosphorylation of protein synthesis markers was decreased in PRRS+ pigs compared with both Ad (P < 0.05) and PF (P < 0.05) pigs. Liver gluconeogenesis was not increased as a result of PRRS; however, liver glycogen was decreased (P < 0.01) in PRRS+ pigs compared with Ad and PF pigs at both time points. Taken together, this work demonstrates the differential impact a viral challenge and nutrient restriction have on metabolism of growing pigs. Although markers of skeletal muscle proteolysis showed limited evidence of increase, markers of skeletal muscle synthesis were reduced during PRRS viral challenge. Furthermore, liver glycogenolysis seems to provide PRRS+ pigs with glucose needed to fuel the immune response during viral challenge.

In ovo injection of ascorbic acid and higher incubation temperature modulate blood parameters in response to heat exposure in broilers

1. This study analysed whether in ovo injection of ascorbic acid before incubation and at high incubation temperature influenced blood characteristics and performance in broilers reared in different temperature conditions. 2. A total of 3,000 fertile eggs from broiler breeders (Cobb®) were randomly divided into three incubation treatments: no ascorbic acid injection and egg incubation at 37.5°C (control); no ascorbic acid injection and egg incubation at 39°C; in ovo ascorbic acid injection prior to incubation (6 µg AA/100 µl water) and egg incubation at 39°C. 3. Male chicks hatched from the three incubation treatments were submitted to three distinct rearing temperatures (control, cold and hot) from the third week of age onwards (540 chicks were divided into 6 treatments with 5 replicates per treatment). 4. Measurements at 42 d showed that, after egg incubation at 39°C, the haematocrit, haemoglobin values, ionised calcium and glucose concentrations were increased and base excess values were reduced. However, in ovo injection of ascorbic acid normalised all these parameters. 5. Partial CO₂ and O₂ pressure were higher with increased rearing temperature. Blood pH was lower when eggs were incubated at 39°C and injected with ascorbic acid. In ovo injection of ascorbic acid induced leucocytosis due to lymphocytosis and heterophilia, restored basophils rate and led to monocytopoenia. Leucocytosis was triggered by hot rearing temperature due to lymphocytosis, eosinophilia and heterophilia. 6. The results obtained in this study showed that in ovo injection of ascorbic acid before incubation may serve as a long-term stimulator and modulator of the broiler immune system, and that high incubation temperatures induce adaptations in the electrolytic balance, minimising or avoiding the occurrence of respiratory alkalosis under hot rearing temperature.

Redressing the balance: including DHA-rich Aurantiochytrium limacinum in broiler diets increases tissue omega-3 fatty acid content and lowers the n-6:n-3 ratio

1. The consumption of sufficient quantities of long chain omega-3 fatty acids (n-3 LCPUFA) from meat and other animal products can lead to a variety of health benefits in humans. The fatty acid content of poultry meat can be increased by feeding birds ingredients that are rich in n-3 LCFUFA 2. The effect of feeding a docosahexaenoic acid (DHA) rich Aurantiochytrium limacinum biomass (AURA) on the fatty acid content of breast and thigh tissues was investigated in a feeding trial with 2880 male Ross 308 broilers. The broiler diets were supplemented with either 0, 0.25, 0.5 or 1% AURA from day 21 to 42 of age. 3. Supplementation significantly increased the DHA content of both breast and thigh meat at an inclusion rate of 1% in the diet, leading to a total of 42 and 46 mg DHA/100 g of fresh breast or thigh tissue respectively. Significant increases in the tissue eicosapentaenoic acid (EPA) concentration were seen alongside a reduced omega-6/omega-3 ratio, improving the nutritional value of the meat for consumers and identifying supplementation of broiler diets with A. limacinum as an effective and sustainable method to increase n-3 LCPUFA consumption in the human population.

Influence of bone meal degelatinisation and calcium source and particle size on broiler performance, bone characteristics and digestive and plasma alkaline phosphatase activity

1. The current experiment was performed to elucidate the effects of degelatinised bone meal (DBM) in combination with different particle sizes of limestone or oyster shell on broiler performance, bone characteristics and digestive and plasma alkaline phosphatase (ALP) activity. 2. Treatments were applied as a 3 × 3 factorial arrangement with three sources of P (DCP, bone meal and DBM) and three particle sizes (50, 100 and 200 µm) of limestone. Chickens were given either DCP or DBM with oyster shell (523 µm), resulting in a total of 11 treatments with 5 replicates of 8 chicks. 3. Performance criteria were measured weekly. Tibia strength, ash, calcium (Ca) and phosphorus (P) content and plasma P and Ca concentration along with plasma and intestinal alkaline phosphatase (ALP) activity and P digestibility were measured on d 14 and 28. 4. Body weight and FCR were improved in chicks which were fed DBM or oyster shell in comparison to the DCP and limestone respectively (P ≤ 0.05). Performance was influenced (P ≤ 0.05) by particle size; with coarser particles BW and feed intake were increased (P ≤ 0.05). Tibia shear force and P content were reduced (P ≤ 0.001), whereas tibia shear energy, length, ash and Ca content were increased by substitution of DCP with DBM or bone meal (P ≤ 0.001; P ≤ 0.05). A significant difference was observed in the tibia length between the chicks fed oyster shell or limestone with different particles (P ≤ 0.05). Plasma P concentration was reduced in chicks were fed with DBM, bone meal and lower limestone particle size. Intestinal ALP activity was increased (P ≤ 0.001) in chicks which were fed DBM, bone meal, oyster shell or coarse particles of limestone. The P digestibility in chicks fed bone meal was lower than that of those fed DBM or DCP (P ≤ 0.01). Overall, gelatin removal from bone meal improved broiler bone characteristics through the P digestibility and intestinal ALP activity enhancement.

Effect of supplementing graded concentrations of non-phytate phosphorus on performance, egg quality and bone mineral variables in White Leghorn layers

1. An experiment was conducted to determine optimal non-phytate phosphorus (NPP) concentrations for White Leghorn (WL) layers (22-72 weeks) fed diet containing 38 g Ca/kg. 2. Eight diets with graded concentrations (1.5-3.25 g/kg in increments of 0.25 g) of NPP were prepared. Each diet was fed to eight pen replicates containing 88 birds in each. Performance data was evaluated in three different phases (phase I-22-37 weeks, phase II-38-53 weeks and phase III-54-72 weeks). Optimum levels of NPP were determined by fitting a quadratic polynomial (QP) regression model. 3. Egg production (EP) was not affected (P = 0.059) by the concentration of NPP and interaction between NPP and diet phase was non-significant, indicating that the lowest concentration (1.5 g/kg diet) of NPP used in the study was adequate across the three phases. However, EP was influenced by phase (P < 0.001). 4. Optimum concentration of NPP for feed intake (FI) was estimated to be 1.5, 1.71 and 2.40 g/kg diet during phases I, II and III, respectively. FI per egg mass (EM) or feed efficiency (FE) responded quadratically with NPP and also differed significantly between phases. Optimum concentration of NPP for FE during phases I, II and III was 1.5, 2.56 and 2.32 g/kg diet, respectively. 5. Egg weight (EW), EM, shell weight and thickness were not affected by NPP concentration although all of these variables (except shell weight) were influenced by phases. 6. Breaking strength of tibia and Ca contents in tibia ash were not affected by the concentration of NPP, but bone ash and P contents in tibia ash were influenced (P < 0.001) by NPP. Predicted optimal concentrations of NPP for responses for tibia ash at 44 or 72 weeks, tibia ash P at 44 weeks and tibia ash P at 72 weeks were 1.55, 2.63 and 1.5 g/kg diet, respectively. 7. Based on the results, it was concluded that WL layers required 1.5 g, 2.63 g and 2.4 g, respectively/kg diet during phase I, II and III with the calculated daily intake of 137.3, 278.3 and 262 mg NPP/b/d.

Effects of dietary supplemental methionine source and betaine replacement on the growth performance and activity of mitochondrial respiratory chain enzymes in normal and heat-stressed broiler chickens

This study aimed to evaluate the effects of dietary supplemental methionine (Met) source and betaine (Bet) replacement for Met on performance and activity of mitochondrial respiratory chain enzymes (MRCEs) in normal and heat-stressed broiler chickens. Total of 1,200-day-old Ross 308 chicks were allocated to two houses, each consisted of 12 treatments, five replicates of 10 birds each with 2 × 2×3 × 2 (temperature × Met source × Met level × Bet, respectively) split-plot factorial arrangement. Met level in the basal diets was 70% requirements (Req) that was increased to the requirement or 130% by supplemental dl- or l-Met. Bet was or was not substituted at the rate of 30% supplemental dl- or l-Met. Feed conversion ratio (FCR) in chicks fed 70% l-Met was lower than those fed 70% dl-Met diet during 1-10 days (p = 0.04). Broilers fed diets containing requirement or 130% Met, regardless of its source, showed higher weight gain (WG) than those received 70% Met diet during 11-42 days (p < 0.001). Feed intake (FI) of broilers fed 130% Met diet was decreased compared to other two groups during 11-42 days (p < 0.05). One hundred thirty percent Met requirement diet resulted in lower FCR comparing to other two groups during 11-42 days (p < 0.001). Heat-stressed birds grew less than those under normal condition (p < 0.05). Broilers fed Req Met diet under normal temperature exhibited higher activities of complexes (Cox) I and III (p < 0.05). Cox I activity in heat-stressed birds fed Bet + diet was similar to those fed Bet-diet under normal temperature (p = 0.046). It is concluded that performance and the activities of Cox I and III were increased as the level of Met increased. Bet replacement for 30% supplemental Met resulted in similar consequences comparing to non-Bet replacement diets on performance, but increased the activity of Cox III. l-Met was effective than dl-Met at the cellular level. High ambient temperature depressed performance and MRCE activity.

Application of omics technologies for a deeper insight into quali-quantitative production traits in broiler chickens: A review

The poultry industry is continuously facing substantial and different challenges such as the increasing cost of feed ingredients, the European Union's ban of antibiotic as growth promoters, the antimicrobial resistance and the high incidence of muscle myopathies and breast meat abnormalities. In the last decade, there has been an extraordinary development of many genomic techniques able to describe global variation of genes, proteins and metabolites expression level. Proper application of these cutting-edge omics technologies (mainly transcriptomics, proteomics and metabolomics) paves the possibility to understand much useful information about the biological processes and pathways behind different complex traits of chickens. The current review aimed to highlight some important knowledge achieved through the application of omics technologies and proteo-genomics data in the field of feed efficiency, nutrition, meat quality and disease resistance in broiler chickens.

Metabolic adaptation of pigs to a Mycoplasma hyopneumoniae and Lawsonia intracellularis dual challenge

Respiratory and enteric pathogens such as Mycoplasma hyopneumoniae (Mh) and Lawsonia intracellularis (LI) reduce lean accretion and feed efficiency (FE) in growing pigs. However, the metabolic mechanism by which this occurs is still unknown. Therefore, the primary aim of this study was to examine the metabolic adaptation of pigs presented with a dual Mh and LI challenge (MhLI). A secondary objective was to examine if selection for high FE, modeled by selection for low residual feed intake (RFI), alters molecular response to disease. Using a 2 × 2 factorial design, 6 littermate pairs from a high RFI (HRFI) and 6 littermate pairs from a low RFI (LRFI) line (barrows, 66 ± 2 kg BW) were selected, with 1 pig from each pair assigned to individual pens in either the challenge or the nonchallenge (control) rooms (n = 6 barrows per line/challenge). On days post inoculation (dpi) 0, MhLI pigs were inoculated intragastrically with LI and intratracheally with Mh. Pig and feeder weights were recorded at dpi 0, 7, 14, and 21. On dpi 21, pigs were euthanized and tissues and blood were collected. Markers of oxidative stress, skeletal muscle metabolism and proteolysis, and liver gluconeogenesis were evaluated to determine the effects of MhLI, RFI line, and their interaction. The interaction of line and challenge was not significant (P > 0.05) for any measure. Overall, MhLI pigs had lower ADG (38%, P < 0.001), ADFI (25%, P < 0.001), and G:F (19%, P = 0.012) compared with controls. As expected, LRFI pigs had lower ADFI (P = 0.028) for the same ADG, giving them greater G:F (P = 0.021) than HRFI pigs. Challenged pigs had greater reactive oxygen species (ROS) production in the LM and liver (P < 0.10) but did not have greater skeletal muscle proteolysis. Liver gluconeogenesis was also not upregulated (P > 0.05) due to MhLI. These results provide further evidence that selection for LRFI does not negatively affect response to disease. In addition, these results suggest that postabsorptive metabolic functions are altered due to MhLI challenge. The MhLI challenge induced mitochondrial dysfunction, evident by greater ROS production, and caused pigs to favor glycolytic energy generation. However, skeletal muscle proteolysis and liver gluconeogenesis were not upregulated during MhLI challenge. These data suggest that during mild disease stress, pigs can meet energy demands without reliance on nutrient mobilization and gluconeogenesis.

Feed conversion ratio, residual feed intake and cholecystokinin type A receptor gene polymorphisms are associated with feed intake and average daily gain in a Chinese local chicken population

Background

The feed conversion ratio (FCR) and residual feed intake (RFI) are common indexes in measuring feed efficiency for livestock. RFI is a feed intake adjusted for requirements for maintenance and production so these two traits are related. Similarly, FCR is related to feed intake and weight gain because it is their ratio. Cholecystokinin type A receptor (CCKAR) plays an important role in animal digestive process. We examined the interplay of these three parameters in a local Chinese chicken population.

Results

The feed intake (FI) and body weights (BW) of 1,841 individuals were monitored on a daily basis from 56 to 105 d of age. There was a strong correlation between RFI and average daily feed intake (ADFI) and a negative correlation between the FCR and daily gain (r_g = − 0.710). Furthermore, we identified 51 single nucleotide polymorphisms (SNPs) in the CCKAR and 4 of these resulted in amino acid mutations. The C334A mutation was specifically associated with FI and the expected feed intake (EFI) (P <  0.01) and significantly associated with the average daily gain (ADG) (P <  0.05). G1290A was significantly associated with FI and EFI (P < 0.05).

Conclusion

FCR is apply to weight selecting, and RFI is more appropriate if the breeding focus is feed intake. And C334A and G1290A of the CCKAR gene can be deemed as candidate markers for feed intake and weight gain.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0261-1) contains supplementary material, which is available to authorized users.

Liver mitochondrial dysfunction and electron transport chain defect induced by high dietary copper in broilers

Copper is an important trace mineral in the diet of poultry due to its biological activity. However, limited information is available concerning the effects of high copper on mitochondrial dysfunction. In this study, 72 broilers were used to investigate the effects of high dietary copper on liver mitochondrial dysfunction and electron transport chain defect. Birds were fed with different concentrations [11, 110, 220, and 330 mg of copper/kg dry matter (DM)] of copper from tribasic copper chloride (TBCC). The experiment lasted for 60 d. Liver tissues on d 60 were subjected to histopathological observation. Additionally, liver mitochondrial function was recorded on d 12, 36, and 60. Moreover, a site-specific defect in the electron transport chain in liver mitochondria was also identified by using various chemical inhibitors of mitochondrial respiration. The results showed different degrees of degeneration, mitochondrial swelling, and high-density electrons in hepatocytes. In addition, the respiratory control ratio (RCR) and oxidative phosphorylation rate (OPR) in liver mitochondria increased at first and then decreased in high-dose groups. Moreover, hydrogen peroxide (H2O2) generation velocity in treated groups was higher than that in control group, which were magnified by inhibiting electron transport at Complex IV. The results indicated that high dietary copper could decline liver mitochondrial function in broilers. The presence of a site-specific defect at Complex IV in liver mitochondria may be responsible for liver mitochondrial dysfunction caused by high dietary copper.

A high-caloric diet rich in soy oil alleviates oxidative damage of skeletal muscles induced by dexamethasone in chickens

Objective: Glucocorticoids (GCs) can induce oxidative damage in skeletal muscles. The purpose of this study was to demonstrate a high caloric (HC) diet rich in soy oil would change the oxidative stress induced by a GC.

Methods: The effect of dexamethasone (DEX) and HC diet on oxidative stress in plasma, skeletal muscles (M. pectoralis major, PM; M. biceps femoris, BF), and mitochondria were determined. The biomarkers of oxidative damage and antioxidative enzyme activity were determined. The fatty acid profile of muscles and the activities of complex I and II in mitochondria were measured.

Results: The results showed that DEX increased the concentrations of oxidative damage markers in plasma, muscles, and mitochondria. The activity of complex I was significantly suppressed by DEX. DEX-chickens had higher proportions of polyunsaturated fatty acids and lower proportions of monounsaturated fatty acids in the PM. A HC diet decreased the levels of oxidative damage biomarkers in plasma, muscles, and mitochondria. The interaction between DEX and diet suppressed the activities of complex I and II in HC-chickens.

Discussion: Oxidative damage in skeletal muscles and mitochondria was the result of GC-induced suppression of the activity of mitochondrial complex I. A HC diet improved the antioxidative capacity and reduced the oxidative damage induced by the GC.

Relationship between residual feed intake and lymphocyte mitochondrial complex protein concentration and ratio in crossbred steers

Rate of oxygen uptake by muscle mitochondria and respiratory chain protein concentrations differed between high- and low-residual feed intake (RFI) animals. The hypothesis of this research was that complex I (CI), II (CII), and III (CIII) mitochondria protein concentrations in lymphocyte (blood) mitochondria were related to the RFI phenotype of beef steers. Daily feed intake (ADFI) was individually recorded for 92 Hereford-crossbreed steers over 63 d using GrowSafe individual feed intake system. Predicted ADFI was calculated as the regression of ADFI on ADG and midtest BW. Difference between ADFI and predicted ADFI was RFI. Lymphocytes were isolated from low-RFI (-1.32 ± 0.11 kg/d; = 10) and high-RFI (1.34 ± 0.18 kg/d; = 8) steers. Immunocapture of CI, CII, and CIII proteins from the lymphocyte was done using MitoProfile CI, CII, and CIII immunocapture kits (MitoSciences Inc., Eugene, OR). Protein concentrations of CI, CII, and CIII and total protein were quantified using bicinchoninic acid colorimetric procedures. Low-RFI steers consumed 30% less ( = 0.0004) feed and had a 40% improvement ( < 0.0001) in feed efficiency compared with high-RFI steers with similar growth ( = 0.78) and weight measurements ( > 0.65). High- and low-RFI steers did not differ in CI ( = 0.22), CII ( = 0.69), and CIII ( = 0.59) protein concentrations. The protein concentration ratios for CI to CII ( = 0.03) were 20% higher and the ratios of CI to CIII ( = 0.01) were 30% higher, but the ratios of CII to CIII ( = 0.89) did not differ when comparing low-RFI steers with high-RFI steers. The similar magnitude difference in feed intake, feed efficiency measurements, and CI-to-CIII ratio between RFI phenotypes provides a plausible explanation for differences between the phenotypes. We also concluded that mitochondria isolated from lymphocytes could be used to study respiratory chain differences among differing RFI phenotypes. Further research is needed to determine if lymphocyte mitochondrial complex proteins can be used for identification of RFI phenotype.

Progesterone signalling in broiler skeletal muscle is associated with divergent feed efficiency

Background

We contrast the pectoralis muscle transcriptomes of broilers selected from within a single genetic line expressing divergent feed efficiency (FE) in an effort to improve our understanding of the mechanistic basis of FE.

Results

Application of a virtual muscle model to gene expression data pointed to a coordinated reduction in slow twitch muscle isoforms of the contractile apparatus (MYH15, TPM3, MYOZ2, TNNI1, MYL2, MYOM3, CSRP3, TNNT2), consistent with diminishment in associated slow machinery (myoglobin and phospholamban) in the high FE animals. These data are in line with the repeated transition from red slow to white fast muscle fibres observed in agricultural species selected on mass and FE. Surprisingly, we found that the expression of 699 genes encoding the broiler mitoproteome is modestly–but significantly–biased towards the high FE group, suggesting a slightly elevated mitochondrial content. This is contrary to expectation based on the slow muscle isoform data and theoretical physiological capacity arguments. Reassuringly, the extreme 40 most DE genes can successfully cluster the 12 individuals into the appropriate FE treatment group. Functional groups contained in this DE gene list include metabolic proteins (including opposing patterns of CA3 and CA4), mitochondrial proteins (CKMT1A), oxidative status (SEPP1, HIG2A) and cholesterol homeostasis (APOA1, INSIG1). We applied a differential network method (Regulatory Impact Factors) whose aim is to use patterns of differential co-expression to detect regulatory molecules transcriptionally rewired between the groups. This analysis clearly points to alterations in progesterone signalling (via the receptor PGR) as the major driver. We show the progesterone receptor localises to the mitochondria in a quail muscle cell line.

Conclusions

Progesterone is sometimes used in the cattle industry in exogenous hormone mixes that lead to a ~20% increase in FE. Because the progesterone receptor can localise to avian mitochondria, our data continue to point to muscle mitochondrial metabolism as an important component of the phenotypic expression of variation in broiler FE.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0396-2) contains supplementary material, which is available to authorized users.

Mitochondrial metabolism: a driver of energy utilisation and product quality?

High feed efficiency is a very desirable production trait as it positively influences resource utilisation, profitability and environmental considerations, albeit at the possible expense of product quality. The modern broiler is arguably the most illustrative model species as it has been transformed over the past half century into an elite feed converter. Some producers are currently reporting that 42-day-old birds gain 1 kg of wet weight for every 1.35 kg of dry weight consumed. Its large breast muscle is exclusively composed of large, low mitochondrial-content Type IIB fibres, which may contribute to low maintenance costs and high efficiency. In an effort to gain a better understanding of individual variation in chicken feed efficiency, our group has been exploring the biology of the mitochondrion at multiple levels of organisation. The mitochondrion is the organelle where much biochemical energy transformation occurs in the cell. Using Cobb-Vantress industrial birds as our primary experimental resource, we have explored the tissue content, structure and function of the mitochondrion and its relationship to growth, development, efficiency and genetic background. While much remains to be understood, recent highlights include (1) variation in muscle mitochondrial content that is associated with performance phenotypes, (2) altered muscle mitochondrial gene and protein expression in birds differing in feed efficiency, (3) variation in isolated mitochondrial function in birds differing in feed efficiency and (4) evidence for an unexpected role for the mitochondrially localised progesterone receptor in altering bird muscle metabolism. Mitochondrial function is largely conserved across the vertebrates, so the same metabolic principles appear to apply to the major production species, whether monogastric or ruminant. A speculative role for the mitochondria in aspects of meat quality and in influencing postmortem anaerobic metabolism will conclude the manuscript.

Relationships between the activity of respiratory-chain complexes in pre- (biopsy) or post-slaughter muscle samples and feed efficiency in random-bred Ghezel lambs

The present study was conducted to determine the relationship between the activity of mitochondrial respiratory chain complexes in pre- and post-slaughter muscle samples and residual feed intake (RFI) in Ghezel male lambs born as a result of random mating. The study was based on the hypothesis that random-bred lambs with lower feed (or higher) RFI have lower (or higher) respiratory chain-complex activity in muscle samples. Lambs (n = 30) were fed a diet consisting of 70% concentrate and 30% alfalfa hay during a 70-day period. Individual feed intake and average daily gain were recorded to calculate the RFI, feed-conversion ratio (FCR) and adjusted FCR (aFCR). On the basis of these calculations, the lambs were classified into low and high groups for RFI, with FCR and aFCR (n = 22) being one standard deviation above or below the means; this was corroborated by Student’s t-test (P &lt; 0.01). At the end of the experiment, a 10-g biopsy sample was taken from the posterior side of the left femoral biceps. After 24 h, the lambs were slaughtered, and a sample from the posterior side of the right femoral biceps was dissected for determination of mitochondrial protein and respiratory chain-complex activities (Complexes I–V). The RFI was not correlated with the metabolic bodyweight and average daily gain, but was positively correlated (r = 0.56) with the average daily feed intake (P &lt; 0.01); mean daily feed intake in the low-RFI group was 200 g less than that in the high-RFI group. The FCR and aFCR were not significantly (P &gt; 0.05) correlated with average daily feed intake (r = 0.39 and r = 0.36 respectively), but showed a negative correlation (P &lt; 0.01) with average daily gain (r = –0.73 and r = –0.76 respectively). Although very high negative correlations were recorded between the activities of all five respiratory-chain complexes and RFI in muscle samples obtained before (–0.91 to –0.97) and after (–0.92 to –0.97) slaughter, Complexes I and V showed small negative correlations (–0.40) with FCR or aFCR (P &lt; 0.05). Enzyme activities of the respiratory-chain Complexes I, III and V were not significantly different between the pre- and post-slaughter biopsy samples; however, the enzyme activities of respiratory-chain Complexes II and IV were slightly higher in post-slaughter samples (P &lt; 0.01). These results suggested that it may be possible to use the enzymatic activity of respiratory-chain complexes in muscle biopsy samples for screening of lambs for RFI, providing a useful procedure for genetic selection of lambs for this component of feed efficiency. These encouraging results need to be verified in further experiments using other sheep breeds and a larger number of lambs.

Relationship between antioxidant capacity, oxidative stress, and feed efficiency in beef steers

Feed efficiency (FE) can vary between individuals but sources of variation are not well characterized. Oxidative stress is among the biological mechanisms believed to contribute to variation. The objective of this study was to evaluate the relationship between FE, antioxidant activity, and oxidative stress in feedlot steers representing phenotypic extremes for FE. Crossbred beef steers ( = 181) fed 70-d growing phase (GP) whole-shell corn-based (G-Corn) or rye baleage and soybean hull-based (G-Rough) diets in GrowSafe bunks at the University of Missouri were shipped to Iowa State University where the 12 most feed efficient (HFE) and 12 least feed efficient (LFE) steers from each diet (n = 48; 467 kg [SD 51]) were selected for evaluation. Steers received diets similar to GP diets, and 3 d after arrival, blood was sampled to evaluate antioxidant activity and oxidative stress markers for the GP following transit. Steers were transitioned to finishing phase (FP) cracked corn-based (F-Corn) or dried distillers' grains and soybean hull-based (F-Byp) diets, and on FP d 97, blood samples for the FP were collected. Data for the GP were analyzed as a 2 × 2 factorial, and data for the FP were analyzed as a 2 × 2 × 2 factorial using PROC MIXED of SAS. No GP diet × FP diet, FP diet × FE group, or 3-way interactions were noted ( ≥ 0.11) for FP measures. Steers fed the G-Rough diet had greater ( = 0.04) GP plasma protein carbonyl concentrations. During the GP, HFE steers had greater ( ≤ 0.04) protein carbonyl and ratio of oxidized:reduced blood lysate glutathione concentrations than LFE steers. There were GP diet × FE group interactions ( ≤ 0.03) during the GP and FP. During the GP, total blood lysate superoxide dismutase (SOD) activity was greater ( ≤ 0.03) in G-Rough/LFE steers than in G-Rough/HFE and G-Corn/LFE steers; G-Corn/HFE steers were intermediate. The G-Rough/LFE steers had greater ( < 0.04) glutathione peroxidase (GPX) activity than other groups and greater ( = 0.03) plasma malondialdehyde concentrations than G-Corn/LFE steers. During the FP, the G-Rough/LFE steers had greater ( ≤ 0.04) GPX activity than G-Rough/HFE and G-Corn/LFE steers; G-Corn/HFE steers were intermediate. The F-Byp diet had greater ( < 0.01) protein carbonyl than the F-Corn diet, and no other FP diet effects were noted ( ≥ 0.3) for any FP measures. The GP diet and FE groups had stronger relationships with antioxidant activity and oxidative stress markers measured for the GP than for the FP. Overall, antioxidant activity may play a role in FE as LFE steers, driven largely by G-Rough/LFE steers, had greater SOD activity and GPX activity than HFE steers, potentially using a greater proportion of energy otherwise available for tissue accretion.

Proteomics of Breast Muscle Tissue Associated with the Phenotypic Expression of Feed Efficiency within a Pedigree Male Broiler Line: I. Highlight on Mitochondria

As feed represents 60 to 70% of the cost of raising an animal to market weight, feed efficiency (the amount of dry weight intake to amount of wet weight gain) remains an important genetic trait in animal agriculture. To gain greater understanding of cellular mechanisms of feed efficiency (FE), shotgun proteomics was conducted using in-gel trypsin digestion and tandem mass spectrometry on breast muscle samples obtained from pedigree male (PedM) broilers exhibiting high feed efficiency (FE) or low FE phenotypes (n = 4 per group). The high FE group had greater body weight gain (P = 0.004) but consumed the same amount of feed (P = 0.30) from 6 to 7 wk resulting in higher FE (P < 0.001). Over 1800 proteins were identified, of which 152 were different (P < 0.05) by at least 1.3 fold and ≤ 15 fold between the high and low FE phenotypes. Data were analyzed for a modified differential expression (DE) metric (Phenotypic Impact Factors or PIF) and interpretation of protein expression data facilitated using the Ingenuity Pathway Analysis (IPA) program. In the entire data set, 228 mitochondrial proteins were identified whose collective expression indicates a higher mitochondrial expression in the high FE phenotype (binomial probability P < 0.00001). Within the top up and down 5% PIF molecules in the dataset, there were 15 mitoproteome proteins up-regulated and only 5 down-regulated in the high FE phenotype. Pathway enrichment analysis also identified mitochondrial dysfunction and oxidative phosphorylation as the number 1 and 5 differentially expressed canonical pathways (up-regulated in high FE) in the proteomic dataset. Upstream analysis (based on DE of downstream molecules) predicted that insulin receptor, insulin like growth receptor 1, nuclear factor, erythroid 2-like 2, AMP activated protein kinase (α subunit), progesterone and triiodothyronine would be activated in the high FE phenotype whereas rapamycin independent companion of target of rapamycin, mitogen activated protein kinase 4, and serum response factor would be inhibited in the high FE phenotype. The results provide additional insight into the fundamental molecular landscape of feed efficiency in breast muscle of broilers as well as further support for a role of mitochondria in the phenotypic expression of FE.

Funding provided by USDA-NIFA (#2013–01953), Arkansas Biosciences Institute (Little Rock, AR), McMaster Fellowship (AUS to WB) and the Agricultural Experiment Station (Univ. of Arkansas, Fayetteville).

Heat stress impairs mitochondria functions and induces oxidative injury in broiler chickens

The objective of this study was to explore the linkage of oxidative stress occurring in mitochondria, skeletal muscles, and plasma in heat stress-challenged broilers. At d 35, 24 broilers were randomly assigned to 2 treatments: rearing at high temperature (32 ± 1°C; heat stress group) or normal temperature (21 ± 1.2°C; control) for 7 d. The oxidative damage of lipid, DNA, and protein and the activities of antioxidative enzymes were measured, respectively, in plasma, skeletal muscles (breast and thigh muscles), and skeletal muscle mitochondria. The result showed that heat exposure increased (P < 0.01) plasma concentrations of thiobarbituric acid reacting substances (TBARS) and 8-hydroxydeoxyguanosine (8-OHdG) whereas it deceased total antioxidant capacity (P < 0.05) and ability to inhibit hydroxyl radicals (AIHR; P< 0.001). Protein carbonyl and TBARS levels were increased (P < 0.001) by heat stress in breast and thigh muscles. In skeletal muscle mitochondria, heat stress increased (P < 0.05) 8-OHdG and suppressed AIHR. Plasma activity of superoxide dismutase (SOD) was increased (P< 0.001) whereas glutathione peroxidase (GSH-Px) was suppressed by heat stress (P < 0.001). Heat exposure increased SOD and catalase activities in breast muscle (P < 0.01) but the reverse was true in thigh muscle (P < 0.05). Glutathione peroxidase was increased in thigh muscle (P < 0.001) but was not changed in breast muscle (P > 0.05). Heat stress increased SOD (P < 0.05) and decreased GSH-Px activities (P < 0.05) of mitochondria regardless of muscle types. Plasma allantoin level increased (P < 0.01) correspondingly with urate (P < 0.001) in heat-stressed broilers, indicating that urate could serve as an antioxidant to enhance the antioxidative capacity during stress in a concentration-dependent manner. The activities of respiratory chain complexes I and III were estimated in skeletal muscle mitochondria. Mitochondrial complex I activity was suppressed (P < 0.01) by heat exposure in breast and thigh muscles but complex III activity was elevated only in breast muscle (P < 0.01) of heat-stressed broiler. The fatty acid composition in skeletal muscle was not influenced by heat stress. In conclusion, suppressed mitochondrial complex I activity is associated with oxidative stress induced by heat exposure, which, in turn, is linked with the oxidative damages in muscle tissues and plasma.

In-Depth Duodenal Transcriptome Survey in Chickens with Divergent Feed Efficiency Using RNA-Seq

Since the feed cost is a major determinant of profitability in poultry industry, how to improve feed efficiency through genetic selection is an intriguing subject for breeders and producers. As a more suitable indicator assessing feed efficiency, residual feed intake (RFI) is defined as the difference between observed and expected feed intake based on maintenance and growth. However, the genetic mechanisms responsible for RFI in chickens are still less well appreciated. In this study, we investigated the duodenal transcriptome architecture of extreme RFI phenotypes in the six brown-egg dwarf hens (three per group) using RNA sequencing technology. Among all mapped reads, an average of 75.62% fell into annotated exons, 5.50% were located in introns, and the remaining 18.88% were assigned to intergenic regions. In total, we identified 41 promising candidate genes by differential expression analysis between the low and high RFI groups. Furthermore, qRT-PCR assays were designed for 10 randomly chosen genes, and nine (90.00%) were successfully validated. Functional annotation analyses revealed that these significant genes belong to several specific biological functions related to digestibility, metabolism and biosynthesis processes as well as energy homeostasis. We also predicted 253 intergenic coding transcripts, and these transcripts were mainly involved in fundamental biological regulation and metabolism processes. Our findings provided a pioneering exploration of biological basis underlying divergent RFI using RNA-Seq, which pinpoints promising candidate genes of functional relevance, is helpful to guide future breeding strategies to optimize feed efficiency and assists in improving the current gene annotation in chickens.

Feed supplemented with byproducts from olive oil mill wastewater processing increases antioxidant capacity in broiler chickens

In the present study, a ceramic membrane microfiltration method was used for the separation of two liquid products, the downstream permeate and the upstream retentate, from olive mill wastewater (OMWW). These liquid products were examined for their antioxidant activity by incorporating them into broilers' feed. Twenty four broilers 13 d old were divided into two feeding groups receiving supplementation with OMWW retentate or permeate for 37 d. Blood was drawn at 17, 27 and 37 d, while tissues (muscle, heart, liver) were collected at 37 d. The antioxidant effects were assessed by measuring oxidative stress biomarkers in blood and tissues. The results showed that broilers given feed supplemented with OMWW retentate or permeate had significantly lower protein oxidation and lipid peroxidation levels and higher total antioxidant capacity in plasma and tissues compared to control group. In both OMWW groups, catalase activity in erythrocytes and tissues was significantly increased compared to control group. OMWW retentate administration increased significantly GSH in erythrocytes in broilers with low GSH, although both OMWW products significantly reduced GSH in broilers with high GSH. Thus, it has been demonstrated for the first time that supplementation with OMWW processing residues could be used for enhancing broilers' redox status.

Transcriptomic analysis to elucidate the molecular mechanisms that underlie feed efficiency in meat-type chickens

Feed efficiency phenotypes defined by genotypes or gene markers are unknown. To date, there are only limited studies on global gene expression profiling on feed efficiency. The objective of this study was to identify genes and pathways associated with residual feed intake (RFI) through transcriptional profiling of duodenum at two different ages in a chicken population divergently selected for low (LRFI) or high (HRFI) RFI. The global gene expression differences in LRFI and HRFI were assessed by the Affymetrix GeneChip(®) Chicken Genome Array and RT-PCR using duodenal tissue on days 35 and 42. The Ingenuity Pathway Analysis program was used to identify canonical and gene network pathways associated with RFI. A global view of gene expression differences between LRFI and HRFI suggest that RFI can be explained by differences in cell division, growth, proliferation and apoptosis, protein synthesis, lipid metabolism, and molecular transport of cellular molecules. Chickens selected for improved RFI achieve efficiency by reducing feed intake with a nominal or no change in weight gain by either up-regulating CD36, PPARα, HMGCS2, GCG or down-regulating PCSK2, CALB1, SAT1, and SGK1 genes within the lipid metabolism, small molecule biochemistry, molecular transport, cell death, and protein synthesis molecular and cellular functions. Chickens selected for reduced RFI via reduced feed intake with no change in weight gain achieve feed efficiency for growth by the up-regulation of genes that reduce appetite with increased cellular oxidative stress, prolonged cell cycle, DNA damage, and apoptosis in addition to increased oxidation of dietary fat and efficient fatty acids transported from the intestines.