M. E. Persia

Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks

This experiment was conducted to evaluate the effects of feeding dietary fiber on cecal short-chain fatty acid (SCFA) concentration and cecal microbiota of broiler and laying-hen chicks. The lower fiber diet was based on corn-soybean meal (SBM) and the higher fiber diet was formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran to contain 60.0 g/kg of both DDGS and wheat bran from 1 to 12 d and 80.0 g/kg of both DDGS and wheat bran from 13 to 21 d. Diets were formulated to meet or exceed NRC nutrient requirements. Broiler and laying-hen chicks were randomly assigned to the high and low fiber diets with 11 replicates of 8 chicks for each of the 4 treatments. One cecum from 3 chicks was collected from each replicate: one cecum underwent SCFA concentration analysis, one underwent bacterial DNA isolation for terminal restriction fragment length polymorphism (TRFLP), and the third cecum was used for metagenomics analyses. There were interactions between bird line and dietary fiber for acetic acid (P = 0.04) and total SCFA (P = 0.04) concentration. There was higher concentration of acetic acid (P = 0.02) and propionic acid (P < 0.01) in broiler chicks compared to laying-hen chicks. TRFLP analysis showed that cecal microbiota varied due to diet (P = 0.02) and chicken line (P = 0.03). Metagenomics analyses identified differences in the relative abundance of Helicobacter pullorum and Megamonas hypermegale and the genera Enterobacteriaceae, Campylobacter, Faecalibacterium, and Bacteroides in different treatment groups. These results provide insights into the effect of dietary fiber on SCFA concentration and modulation of cecal microbiota in broiler and laying-hen chicks.

Genomic analysis of Ugandan and Rwandan chicken ecotypes using a 600 k genotyping array

BackgroundIndigenous populations of animals have developed unique adaptations to their local environments, which may include factors such as response to thermal stress, drought, pathogens and suboptimal nutrition. The survival and subsequent evolution within these local environments can be the result of both natural and artificial selection driving the acquisition of favorable traits, which over time leave genomic signatures in a population. This study’s goals are to characterize genomic diversity and identify selection signatures in chickens from equatorial Africa to identify genomic regions that may confer adaptive advantages of these ecotypes to their environments.ResultsIndigenous chickens from Uganda (nu2009=u200972) and Rwanda (nu2009=u2009100), plus Kuroilers (nu2009=u200924, an Indian breed imported to Africa), were genotyped using the Axiom® 600xa0k Chicken Genotyping Array. Indigenous ecotypes were defined based upon location of sampling within Africa. The results revealed the presence of admixture among the Ugandan, Rwandan, and Kuroiler populations. Genes within runs of homozygosity consensus regions are linked to gene ontology (GO) terms related to lipid metabolism, immune functions and stress-mediated responses (FDRu2009<u20090.15). The genes within regions of signatures of selection are enriched for GO terms related to health and oxidative stress processes. Key genes in these regions had anti-oxidant, apoptosis, and inflammation functions.ConclusionsThe study suggests that these populations have alleles under selective pressure from their environment, which may aid in adaptation to harsh environments. The correspondence in gene ontology terms connected to stress-mediated processes across the populations could be related to the similarity of environments or an artifact of the detected admixture.

Single nucleotide variant discovery of highly inbred Leghorn and Fayoumi chicken breeds using pooled whole genome resequencing data reveals insights into phenotype differences

BackgroundAnalyses of sequence variants of two distinct and highly inbred chicken lines allowed characterization of genomic variation that may be associated with phenotypic differences between breeds. These lines were the Leghorn, the major contributing breed to commercial white-egg production lines, and the Fayoumi, representative of an outbred indigenous and robust breed. Unique within- and between-line genetic diversity was used to define the genetic differences of the two breeds through the use of variant discovery and functional annotation.ResultsDownstream fixation test (FST) analysis and subsequent gene ontology (GO) enrichment analysis elucidated major differences between the two lines. The genes with high FST values for both breeds were used to identify enriched gene ontology terms. Over-enriched GO annotations were uncovered for functions indicative of breed-related traits of pathogen resistance and reproductive ability for Fayoumi and Leghorn, respectively.ConclusionsVariant analysis elucidated GO functions indicative of breed-predominant phenotypes related to genomic variation in the lines, showing a possible link between the genetic variants and breed traits.

Comparative omega-3 fatty acid enrichment of egg yolks from first-cycle laying hens fed flaxseed oil or ground flaxseed

&NA; When laying hen diets are enriched with omega‐3 polyunsaturated fatty acids to generate value‐added eggs for human consumption markets, concentrations of alpha‐linolenic (ALA), eicosapentaenoic (EPA), and docosahexaenoic acids (DHA) in the yolk can reach 250 mg/50 g whole egg. Flaxseed, a rich source of ALA, is commonly used for omega‐3 enrichment; however, the impact of dietary flaxseed source (extracted oil vs. milled seed) on fatty acid transfer to egg yolk in laying hens is unknown. Therefore, transfer of ALA, EPA, and DHA into egg yolk from extracted flaxseed oil or milled flaxseed was evaluated in Hy‐Line W‐36 laying hens over an 8‐week feeding period (25 to 33 wk old). Hens (n = 132) were randomly housed with 3 birds/cage (4 replicates/treatment) for each of the 11 treatment groups. Diets were isocaloric and consisted of a control diet, 5 flaxseed oil diets (0.5, 1.0, 2.0, 3.0, or 5.0% flaxseed oil), and 5 milled flaxseed diets (calculated flaxseed oil concentration from milled flaxseed 0.5, 1.0, 2.0, 3.0, 5.0%). Increasing dietary concentrations of flaxseed oil and milled flaxseed resulted in increased ALA, EPA, and DHA concentration in egg yolk, and fatty acid deposition from flaxseed oil was 2 times greater compared to milled flaxseed when fed at the same dietary inclusions (P < 0.01). Egg yolk EPA and DHA concentrations were not different due to oil or milled source (P = 0.21); however, increasing dietary inclusion rates of flaxseed oil from either source increased yolk EPA and DHA (P < 0.01). Hens fed either flaxseed oil or milled flaxseed resulted in reduced BW change as dietary concentrations increased (P = 0.02). Feed efficiency increased as flaxseed oil increased in concentration, while feeding milled flaxseed decreased feed efficiency (P = 0.01). Analysis of the nitrogen corrected apparent metabolizable energy of flaxseed oil resulted in 7,488 kcal/kg on an as‐fed basis. Dietary flaxseed oil improved feed efficiency and increased ALA deposition into yolk compared to a milled source, demonstrating flaxseed oil to be a viable alternative for ALA egg enrichment.

Satellite cell-mediated breast muscle regeneration decreases with broiler size.

ABSTRACT Satellite cells (SCs) reside between the sarcolemma and basal lamina of muscle fibers and are the primary contributor of DNA for post‐hatch muscle growth and repair. Alterations in SC content or properties by intrinsic and extrinsic factors can have detrimental effects on muscle health and function, and ultimately meat quality. We hypothesized that disrupted SC homeostasis may account in part for the increased breast myopathies observed in growing broilers. To test this hypothesis, we selected broilers with different body weights at comparable ages and studied SC characteristics in vitro and in vivo. Data shows that SC numbers in the breast muscles decrease (P < 0.001) and their inherent abilities to proliferate and differentiate diminish (P < 0.001) with age and size. Further, when breast muscle is presented with an insult, muscle of larger broilers regenerates more slowly than their smaller, age‐matched counterparts arguing that SC quality changes with size and age. Together, our studies show that birds with greater muscle hypertrophy have less SCs with diminished ability to function, and suggest that aggressive selection for breast growth in broilers may exhaust SC pools when birds are grown to heavier processing weights. These findings provide new insights into a possible mechanism leading to breast myopathies in the poultry industry and provide targets for mitigating adverse fresh breast quality.

Genomic Comparison of Indigenous African and Northern European Chickens Reveals Putative Mechanisms of Stress Tolerance Related to Environmental Selection Pressure

Global climate change is increasing the magnitude of environmental stressors, such as temperature, pathogens, and drought, that limit the survivability and sustainability of livestock production. Poultry production and its expansion is dependent upon robust animals that are able to cope with stressors in multiple environments. Understanding the genetic strategies that indigenous, noncommercial breeds have evolved to survive in their environment could help to elucidate molecular mechanisms underlying biological traits of environmental adaptation. We examined poultry from diverse breeds and climates of Africa and Northern Europe for selection signatures that have allowed them to adapt to their indigenous environments. Selection signatures were studied using a combination of population genomic methods that employed FST, integrated haplotype score (iHS), and runs of homozygosity (ROH) procedures. All the analyses indicated differences in environment as a driver of selective pressure in both groups of populations. The analyses revealed unique differences in the genomic regions under selection pressure from the environment for each population. The African chickens showed stronger selection toward stress signaling and angiogenesis, while the Northern European chickens showed more selection pressure toward processes related to energy homeostasis. The results suggest that chromosomes 2 and 27 are the most diverged between populations and the most selected upon within the African (chromosome 27) and Northern European (chromosome 2) birds. Examination of the divergent populations has provided new insight into genes under possible selection related to tolerance of a population’s indigenous environment that may be baselines for examining the genomic contribution to tolerance adaptions.

The impact of β-glucans on performance and response of broiler chickens during a coccidiosis challenge

Abstract Coccidiosis is a costly parasitic disease to the poultry industry with multiple prevention methods being explored to control its impact. This study evaluated the feeding effects of &bgr;‐glucans on performance and responses of chickens during a coccidiosis challenge. Cobb 500 male broilers (n = 1280) were assigned to 1 of 8 treatment groups (8 replicate pens; 20 birds/pen) in a 2 × 4 factorial arrangement, including non‐infected and Eimeria‐infected birds fed for 28 d a control diet, control + BG (150 g/MT Algamune 50), control + BGZn (100 g/MT Algamune 50 Zn), and control + 0.01% Salinomycin (Sal). On d15, birds in the challenge groups received a mixed Eimeria inoculum. Birds and feed were weighed weekly on a per pen basis to evaluate body weight gain (BWG), feed intake (FI), and feed conversion ratios (FCR). Lesion scores were assessed 6 d post infection (d21) on 3 birds per pen. Performance data were subjected to ANOVA and differences were established using the LS‐MEANS statement with significance reported at P ≤ 0.05. There were minor differences in lesion scores among the dietary treatments in the infected groups with reduced duodenal and cecal scores in the Sal group compared to the BGZn and BG groups, respectively. The coccidiosis challenge main effect resulted in a significant reduction in 0‐28 d BW and FI. Dietary treatment resulted in non‐significant effect on BWG, but Sal addition resulted in increased FI. A significant diet X challenge interaction resulted in higher FCR in the Eimeria‐challenged birds supplemented with Sal and BGZn in comparison to the other challenged groups, likely due to reduced mortality in the challenged Sal and BGZn groups. Body composition analysis at d28 revealed that the Eimeria challenge reduced both fat and lean tissue contents, where the &bgr;‐glucans and Sal birds had lower fat percent than control birds.

Evaluation of the Valine requirement of small-framed first cycle laying hens

ABSTRACT An experiment was conducted to evaluate the total Valine (Val) requirement of first cycle laying hens from 41 to 60 wk of age. A total of 270 Hy‐line W‐36 laying hens were randomly assigned to 6 treatments with 15 replicate groups of 3 birds for each experimental unit. A Val deficient basal diet was formulated with corn and peanut meal with analyzed Val, Lys and crude protein concentrations of 0.515, 0.875, and 13.38%, respectively. Synthetic L‐Val was supplemented to the basal diet in 0.070% increments to generate experimental diets containing 0.515, 0.585, 0.655, 0.725, 0.795, and 0.865% Val respectively. A controlled feeding program was applied during the experiment resulting in approximately 95 g feed intake per hen per day. Linear broken line, quadratic broken line, quadratic polynomial and exponential models were used to estimate the Val requirement of the hens based on hen‐housed egg production (HHEP), egg mass (EM), and feed conversion ratio (FCR). Hen‐housed egg production ranged from 48.3 to 81.4%, dependent upon dietary concentration of Val. Val requirements estimated by linear broken line, quadratic broken line, quadratic polynomial and exponential models were reported. Using the linear broken line model, the Val requirement was highest for egg mass, 597.3 mg/d, followed by egg production, 591.9 mg/d and lowest for FCR, 500.5 mg/d.

Evaluation of the tryptophan requirement of small-framed first cycle laying hens

ABSTRACT An experiment was conducted to evaluate the total Trp requirement of first cycle laying hens from 41 to 60 wk of age. In total, 270 Hy‐Line W36 laying hens were randomly allocated to six treatments with 15 replicate groups of three birds for each experimental unit. A Trp‐deficient basal diet was formulated with corn, corn gluten meal, and soybean meal with determined Trp, Lys, and crude protein concentrations of 0.096%, 0.873%, and 15.0%, respectively. Synthetic L‐Trp was supplemented to the basal diet in 0.020% increments to generate experimental diets containing 0.096%, 0.116%, 0.136%, 0.156%, 0.176%, and 0.196% Trp, respectively. Hens were provided a controlled amount of feed of approximately 95 g/d. The diet containing the lowest concentration of Trp resulted in reduced egg production and was halted at 45 wk of age due to low performance with all other dietary treatments reaching the conclusion of the experiment at 60 wk of age. Plasma serotonin responded to dietary Trp concentration, but was not a good candidate for Trp requirement estimation. Linear broken line, quadratic broken line, quadratic polynomial, and exponential models were used to estimate Trp requirement based on hen‐housed egg production (HHEP), egg mass (EM), and feed conversion ratio (FCR). HHEP ranged from 50.7% to 81.0%, dependent upon dietary concentration of Trp. Tryptophan requirements estimated by linear broken line, quadratic broken line, quadratic polynomial, and exponential models were reported. Using the linear broken line model, Trp requirement was highest for EM, 155.8 mg/d, followed by egg production, 153.2 mg/d and lowest for FCR, 140.4 mg/d.

Regions of Genomic Control Identified for Feed Efficiency in Laying Hens under Heat Stress

Recommended Citation Rowland, Kaylee; Hsieh, John C.F.; Barrett, Nathaniel; Ashwell, Chris M.; Persia, Mike E.; Rothschild, Max F.; Schmidt, Carl; and Lamont, Susan J. (2018) Regions of Genomic Control Identified for Feed Efficiency in Laying Hens under Heat Stress, Animal Industry Report: AS 664, ASL R3254. DOI: https://doi.org/10.31274/ans_air-180814-308 Available at: https://lib.dr.iastate.edu/ans_air/vol664/iss1/52