Improved Feed Efficiency Research Articles

Efficacy and Growth Performance between Two Different Ionophore Coccidiostats (Narasin and Salinomycin) in Broiler Chickens after Challenge with Eimeria spp.

The objective of this study was primarily to assess the different performance impacts of two ionophore coccidiostats (narasin and salinomycin) used to manage coccidiosis. While both products may be efficacious in controlling disease challenges, previous literature has suggested that some ionophores are less well tolerated by the broiler chickens. In this study, we were particularly interested to know how the use of different coccidiostat programs translates into broiler health and performance, as measured by zootechnical parameters such as the feed conversion ratio, average daily gain, and final body weight. A total of 352 male Ross 308 one-day-old broilers were randomly divided into two treatment groups (T1 and T2). Treatment 1 included a basal diet (BD) + nicarbazin/narasin (Maxiban®, Elanco) at 100 ppm 0-24 days, narasin at 70 ppm 25-42 days, and (2) Treatment 2 included basal diet + nicarbazin/narasin at 100 ppm 0-24 days, salinomycin (Sacox®, Huvepharma) at 70 ppm 25-42 days. Efficacy and performance parameters, slaughter analysis, dry matter (DM) in litter, and intestinal integrity (I2) were measured for the broilers from both treatment groups. The findings demonstrated more favorable results for broilers reared in the group diet fed with narasin (in the finisher phase), including higher daily body weight gain, higher final body weight, lower feed conversion ratio value (improved feed efficiency), and higher European Production Efficiency Factor value, compared with the salinomycin-supplemented group.

Effect of increasing supplementation of dietary glycine on growth performance, meat quality, liver characteristics, and intestinal health in broiler chickens raised under heat stress conditions

The current study aimed to investigate the effect of increasing supplementation of dietary glycine (Gly) on growth performance, meat quality, liver characteristics, and intestinal health in broiler chickens raised under heat stress (HS) conditions. A total of one thousand six hundred 25-d-old broiler chickens were randomly allotted to 1 of 5 dietary treatments with 8 replicates. Each replicate comprised 20 male and 20 female birds. A negative control (NC) diet was prepared to meet or exceed energy and nutrient requirement estimates, whereas a positive control (PC) diet was formulated to contain increasing concentrations of AMEn by 50 kcal/kg as well as those of digestible amino acids, total Ca, and available P by 10% compared with the respective concentrations in the NC diet. Three additional diets were prepared by supplementing the NC diet with 0.4, 0.8, or 1.6% Gly. All chickens were raised under cyclic HS conditions at 29°C ± 0.89°C for 10 h/d and 23°C ± 1.45°C for the remaining time over an 18-d feeding trial. Results indicated that broiler chickens fed the NC diet had a greater (P < 0.05) FCR than those fed the PC diet under HS conditions. Increasing supplementation of up to 1.6% Gly in diets decreased (linear, P < 0.001) FCR in broiler chickens. Increasing supplementation of dietary Gly tended to increase (linear, P = 0.070) water holding capacity in the breast meat. Increasing supplementation of dietary Gly decreased (linear, P < 0.05) serum aspartate aminotransferase concentrations and tended to decrease blood heterophil:lymphocyte (linear, P = 0.083) and liver malondialdehyde concentrations (quadratic, P = 0.084). A tendency for increased villus height (linear, P = 0.086) and a significant increase in villus height:crypt depth ratio and goblet cell numbers (linear, P < 0.05) were identified following increasing Gly supplementation. In conclusion, increasing supplementation of dietary Gly improved feed efficiency, meat quality, liver health, and intestinal morphology possibly by mitigating oxidative stress and stress response in broiler chickens raised under HS conditions.

Relationship between the rumen microbiome and liver transcriptome in beef cattle divergent for feed efficiency

BackgroundFeed costs account for a high proportion of the variable cost of beef production, ultimately impacting overall profitability. Thus, improving feed efficiency of beef cattle, by way of determining the underlying genomic control and selecting for feed efficient cattle provides a method through which feed input costs may be reduced whilst also contributing to the environmental sustainability of beef production. The rumen microbiome dictates the feed degradation capacity and consequent nutrient supply in ruminants, thus potentially impacted by feed efficiency phenotype. Equally, liver tissue has been shown to be responsive to feed efficiency phenotype as well as dietary intake. However, although both the rumen microbiome and liver transcriptome have been shown to be impacted by host feed efficiency phenotype, knowledge of the interaction between the rumen microbiome and other peripheral tissues within the body, including the liver is lacking. Thus, the objective of this study was to compare two contrasting breed types (Charolais and Holstein-Friesian) divergent for residual feed intake (RFI) over contrasting dietary phases (zero-grazed grass and high-concentrate), based on gene co-expression network analysis of liver transcriptome data and microbe co-abundance network of rumen microbiome data. Traits including RFI, dry matter intake (DMI) and growth rate (ADG), as well as rumen concentrations of volatile fatty acids were also included within the network analysis.ResultsOverall, DMI had the greatest number of connections followed by RFI, with ADG displaying the fewest number of significant connections. Hepatic genes related to lipid metabolism were correlated to both RFI and DMI phenotypes, whilst genes related to immune response were correlated to DMI. Despite the known relationship between RFI and DMI, the same microbes were not directly connected to these phenotypes, the Succiniclasticum genus was however, negatively connected to both RFI and ADG. Additionally, a stepwise regression analysis revealed significant roles for both Succiniclasticum genus and Roseburia.faecis sp. in predicting RFI, DMI and ADG.ConclusionsResults from this study highlight the interactive relationships between rumen microbiome and hepatic transcriptome data of cattle divergent for RFI, whilst also increasing our understanding of the underlying biology of both DMI and ADG in beef cattle.

In situ Single-Pass Perfused Rabbit Intestinal Study sample Analysis of Ractopamine by UPLC

In recent years, the prediction of oral drug absorption in humans has been a challenge for researchers and many techniques for permeability studies have been developed for several purposes, including biowaiver processes. The Single-Pass Intestinal Perfusion (SPIP) method performed in rats can provide permeability results closest to in vivo condition. he use of SPIP in rats and calculations for absorption prediction in humans may indicate the transport mechanisms and/or pre-systemic metabolism involved on permeation processes of drugs, since this model is the closest to in vivo conditions. Ractopamine hydrochloride is a commercial beta-adrenergic agonist commonly used as a dietary supplement in cattle production for improved feed efficiency and growth promotion. Currently, regulatory target tissues (as approved in the New Animal Drug Application with Food and Drug Administration) for ractopamine residue testing are muscle and liver. The aim of the study is to develop and validate an UPLC assay method to determine whether detectable and quantifiable levels of perfused ractopamine in small intestine of cattle or not. The separation is carried on Acquity UPLC BEH C18 (150mm x 2.1mm, 1.7 µm) reversed phase column using acetonitrile and 0.01M ammonium formate as the mobile phase in gradient mode at flow rate of 0.5mL/min. The precision, accuracy, extraction recovery, matrix effect, and stability meet the requirements of the guiding principles. In order to verify the sensitivity and selectivity of the method in a real-time situation, the developed method is successfully applied to a perfusion study in small intestine of rabbit and the samples were analyzed by Empower software.

PSVII-9 Improvement of feed efficiency in Korean Hanwoo cattle: investigation of feed intake and analysis of residual feed intake (RFI)

Abstract Feed efficiency is an important economic trait in beef cattle production, and improving feed efficiency can reduce production costs and environmental impact. Residual feed intake (RFI) is a useful measure of individual feed efficiency, representing the difference between the actual feed intake of an animal and its predicted feed intake based on its body weight (BW) and growth. This study aimed to investigate feed intake and analyze RFI in Hanwoo cattle to improve feed efficiency. Data were collected from 120 Hanwoo steers (9 to 11 mo old) from six different test stations across the country. Individual daily feed intake of concentrates and forage was recorded over 70 d, and BW was measured at the beginning and end of the feeding trial. Daily feed intake was calculated using the TDN values of the concentrates and forage. Expected feed intake was estimated using a linear regression model based on metabolic BW and daily gain. RFI was calculated as the difference between expected and actual feed intake. Average daily gain ranged from 1.05 to 1.71 kg/d, and average daily feed intake ranged from 5.10 to 7.72 kg/d across the test stations. RFI values ranged from -0.84 to 0.95 kg/d, indicating significant variation in feed efficiency among the animals. This study provides valuable information on feed intake and RFI in Hanwoo cattle. Further research with a larger dataset is needed to develop a genetic evaluation model for RFI and to select animals with superior feed efficiency for improving Hanwoo cattle production.

PSIX-30 Interaction between rumen microbiome and host feed efficiency phenotype across contrasting breeds and dietary sources

Abstract Provision of feed accounts for a high proportion of the variable cost in beef production systems, and consequently is a major determinant of overall profitability. Thus, improving the conversion of feed to animal product by identifying and breeding cattle with improved feed efficiency potential provides a method through which feed input costs may be reduced, whilst also contributing to more environmentally sustainable beef production. The rumen microbiome dictates the feed degradation capacity and subsequent nutrient supply in ruminants and is thus potentially impacted by feed efficiency phenotype. However, the relationship between rumen microbiota and host feed efficiency phenotype is yet to be fully elucidated. This is further complicated when contrasting diets, cattle breeds as well as various stages of animal development are considered. The objective of this study was to undertake network analysis on rumen microbiome data generated from two contrasting steer breed types (Charolais and Holstein-Friesian), divergent within-breed for residual feed intake (RFI), and offered contrasting diets during different stages of development: i) high-concentrate during the growing phase; ii) grass silage during the growing phase; iii) zero-grazed grass during the growing phase, and iv) high-concentrate during the finishing phase. From approximately 10 mo of age, Charolais (n = 90) and Holstein-Friesian (n = 77) steers were individually fed each of the aforementioned diets for 70 d, following an adaptation period between each diet. At the end of each dietary phase, RFI was determined for every steer and rumen fluid was sampled using a transesophageal sampling device from the 10 most-efficient (Low-RFI) and the 10 least-efficient (High-RFI) steers within each breed. Rumen fluid samples were then subjected to 16S rRNA sequencing and a network-based systems biology analysis subsequently undertaken using PCIT incorporating the 16S sequencing data and individual RFI values across each breed and dietary phase. A total of 110 microbial taxa were connected (P &amp;lt; 0.05; r &amp;gt; 0.8) to the breed and diet contrasts examined; however, no single microbe was commonly connected to all contrasts. The Pyramidobacter genus was the most represented phylotype, displaying a positive connection with the Charolais steers during the grass silage diet, as well as a negative association with Charolais steers during the first high-concentrate diet and Holstein-Friesian steers during the zero-grazed grass diet. Similarly, of the 35 microbial taxa significantly connected to more than one breed/diet contrast, 12 displayed altered direction of association, indicating a differential relationship between the rumen microbiome and RFI phenotype depending on the prevailing dietary management. Acknowledgement: The animal model used in this study was funded by the Irish Department of Agriculture, Food and the Marine (RSF13/S/519). Kate Keogh received funding for this work from the Research Leaders 2025 program (co-funded by Teagasc and the European Union’s Horizon 2020, Marie Skłodowska-Curie grant agreement number 754380).

PSVI-6 Genomic determinants of the rumen microbiome and metabolome in Angus steers

Abstract The rumen microbiome provides approximately 70% of energy required for the ruminant host through fermentation byproducts. Due to microbial impacts on host health and productivity, several studies have associated microbiome and metabolome variation with important sustainability phenotypes, such as feed efficiency and methane emissions. Recent studies have indicated the microbial communities present in rumen fluid are under low-to-moderate host genetic control. However, microorganisms present on the rumen wall have been underrepresented in research, negating their unique role in host-microbiome interactions. Current studies investigating heritability of the rumen planktonic microorganisms are plagued by small sample sizes, high management and breed heterogeneity, and low resolution for classifying microbial communities. To determine the heritability of the rumen fluid and epithelium-associated microbiome and metabolome, Angus steers (n = 350) were enrolled in a 70-d feed efficiency trial, where real-time dry matter intake was measured. Body weights were collected throughout the trial to calculate average daily gain and residual feed intake. Mid-trial, a novel surgery method was used to swab the rumen wall to capture epithelium-associated microorganisms. On d 70, 50 mL of rumen fluid was obtained from steers using orogastric tubing for collection of planktonic microbial communities. Metagenomic DNA extracted from both rumen fluid and epimural samples was used for reduced representation sequencing to predict microbial features such as diversity, composition, and putative function. Genomic DNA isolated from whole blood was used to perform low-pass whole genome sequencing for use in downstream heritability estimates and variant association analyses. Many core microbial abundances are under low-to-moderate host genetic control (h2 &amp;gt; 0.15; P &amp;lt; 0.05); however, many microorganisms had low heritability estimates (h2 &amp;lt; 0.10). Preliminary genome-wide associations studies are vastly underpowered to detect host genetic variants associated with microbial features, but data generated using the total number of animals will better refine these polymorphisms. Several key heritable metabolites were identified in amino acid metabolism pathways in rumen fluid (P &amp;lt; 0.05). The rumen microbiome appears to act as a complex polygenic trait and incorporating microbial features into prediction models may improve feed efficiency estimations. Understanding host genetic control of the rumen microbiome and metabolome may empower downstream applications to enhance genomic and phenotypic predictions for feed efficiency and other sustainability traits in beef cattle.

358 The effect of increasing dietary limestone concentration on growth performance, gas flux, and carcass characteristics in finishing beef cattle

Abstract Reducing methane (CH4) emissions from beef cattle is desirable as CH4 is a greenhouse gas that represents an energetic loss from the production system. Limestone is commonly fed to cattle as a source of calcium but may also act as a rumen buffer and decrease CH4 emissions by limiting hydrogen availability for methanogenesis. The objective of this experiment was to determine if diet limestone concentration influences growth performance, gas flux, and carcass characteristics in finishing beef cattle. Yearling steers [n = 16; initial body weight (BW) 619 ± 34 kg] were stratified by BW and randomly assigned to 1 of 2 isocaloric and isonitrogenous dietary treatments in a completely randomized design where limestone was included at 1.3% (1X) or 2.6% (2X) of diet dry matter (DM). Finishing diets were formulated to contain 0.43 or 0.96% DM as Ca and were fed ad libitum using automated cattle feeders (SmartFeed Pro; C-Lock Inc.; Rapid City, SD) in a single pen for the final 37 d of finishing. Body weights were measured on d -1, 0, 36, and 37. An automated head chamber system (GreenFeed; C-Lock Inc.) was used to measure gas flux. Analysis of variance was conducted using JMP Pro 17 to determine the fixed effect of treatment with individual animal as the experimental unit. Statistical significance was defined as P ≤ 0.05 with a tendency defined as 0.05 &amp;lt; P ≤ 0.10. Increasing the dietary limestone concentration from 1.3 to 2.6% of DM did not influence DM intake, but numerically increased final shrunk BW (P = 0.68) and hot carcass weight (P = 0.75) and increased average daily gain (ADG; P = 0.02) and gain to feed ratio (G:F) by approximately 12%. Cattle fed the 2X diet tended to have 6.5% greater ribeye area (P = 0.09), but similar USDA yield grade, backfat thickness, and dressing percentage (P ≥ 0.34) when compared with cattle fed the 1X diet. Daily CO2 and CH4 emissions, daily O2 consumption, CH4 yield, and respiratory quotient were unaffected by treatment (P ≥ 0.47). The improvement in ADG resulted in a tendency for CH4 emission intensity to be decreased by 9.1% (P = 0.09) when the concentration of limestone was 2.6% of dietary DM. While increasing dietary limestone concentration from 1.3 to 2.6% of diet DM did not influence absolute daily CH4 emissions, it increased ADG through an improvement in feed efficiency, which translated to a tendency for a reduction in CH4 emission intensity. These preliminary data suggest that there may be a benefit to feeding limestone or calcium at levels greater than currently recommended by the NASEM (2016). Future research should focus on determining optimum dietary limestone or calcium levels for finishing cattle.

463 Cyber-Physical Systems with robots and AI for precision dairy farming

Abstract The emergence of precision livestock farming (PLF) offers a transformative lens through which to prioritize animal welfare. At the heart of this transformation lies the rumen, a complex microbial ecosystem within dairy cows responsible for converting feed into nutrients and impacting cow health, productivity, and environmental footprint. Despite its pivotal role, our understanding of the inner workings of the rumen remains limited due to a lack of real-time monitoring tools. My research leverages AI and robotics in PLF to address this gap, focusing on developing a closed-loop system for continuous, in-vivo rumen monitoring. This system employs cyber-physical systems (CPS) embedded with modular sensors and adaptive algorithms. These sensor modules, powered by AI-based data tracking, autonomously monitor rumen temperature, humidity, pressure, and methane concentration, enabling early detection of imbalances and prompt interventions to maintain optimal rumen health. A key innovation is the self-powered in-vivo robot capable of traversing the rumen’s stratified layers. Guided by AI-powered localization, this robot unlocks unparalleled access to new data, aiding in identifying specific regions associated with conditions like subacute ruminal acidosis (SARA) and methane production. This non-invasive approach eliminates the need for traditional cannulation, minimizing stress on the animal and opening new avenues for animal scientists. The impact of this research extends beyond individual cow health. By optimizing rumen function, we can improve feed efficiency, reduce methane emissions, and promote overall sustainability in dairy farming. Additionally, real-time data insights pave the way for precision nutrition, tailored interventions, and improved disease prevention, directly enhancing animal welfare. This novel approach to rumen monitoring represents a significant step towards realizing the full potential of PLF. By integrating AI and robotics, we can usher in a future where animal welfare and environmental sustainability go hand-in-hand, ultimately contributing to a more responsible and ethical dairy industry.

197 Hepatic mRNA expression of innate and adaptive immune genes in beef steers with divergent residual body weight gain

Abstract Immune function has a pivotal role in dictating the overall health and productivity of cattle. In a proficient immune system, the liver assumes an integral function in detoxification and metabolic processes and contributes substantially to overall production and immunity. In this study, we evaluated the hepatic mRNA expression of genes involved in innate and adaptive immunity in crossbred beef steers with positive or negative residual body weight (BW) gain (RADG). Positive-RADG beef steers (n = 8; RADG = 0.76 kg/d) and negative-RADG beef steers (n = 8; RADG = -0.64 kg/d) were identified from a group of 108 growing crossbred beef steers (average BW = 286 ± 380kg) after a 56-d performance testing period. At the end of the 56-d period, liver tissue samples were collected from the beef steers for RNA extraction and cDNA synthesis. The mRNA expression of 84 genes involved in innate and adaptive immunity were analyzed using pathway-focused PCR-based arrays. The mRNA expression of genes with false discovery rate-adjusted P-values (FDR) ≤ 0.05 and absolute fold change (FC) ≥ 1.2 were determined to be differentially expressed. Out of the 84 genes analyzed, four genes [interleukin (IL)-2, MYD88, CD-80, NFkB-1] were differentially expressed and were all upregulated in positive compared with negative-RADG beef steers. Gene ontology pathway enrichment analysis of the differentially expressed genes revealed that pathways related to positive regulation of IL-17 production, cellular response to lipopolysaccharide, and positive regulation of lymphocyte activation were enriched in the positive-RADG steers (P ≤ 0.05). In conclusion, our study revealed that positive-RADG beef steers had increased expression of genes and pathways involved in pathogen recognition and initiation of responses to effectively fight off infections while mitigating excess inflammatory reactions compared with negative-RADG steers, which might explain, in part, the improved feed efficiency of these beef animals

236 Increased dietary protein supports key metabolic and intestinal tissue functions in weaned pigs, without increasing gastrointestinal pathogen abundance

Abstract A common dietary strategy to prevent diarrhea in weaned pigs is feeding low protein diets in the period immediately following weaning. The goal of this intervention is to decrease dietary protein sufficiently to reduce pathogen proliferation and protein fermentation without negatively impacting growth performance. One potential alternative to low protein diets is provision of dietary fiber. However, many studies examining the role of protein and fiber on gastrointestinal microbiota and post-weaning diarrhea are complicated by the presence of other substrates, including polyphenols and antinutritional factors in complex ingredients. To assess the role of increased protein and fiber on gut microbiota and host metabolism, semi-purified diets differing in crude protein (CP) and crude fiber (CF) were fed to weaned pigs (n = 40; 28 d of age). Diets with high protein (HP; CP 24.3%, CF 6.4%), high fiber (HF; CP 18.9%, CF 9.4%), or both (HFHP; CP 24.9%, CF 9.5%) were compared with a control (CON; CP 18.1%, CF 6.3%) diet with industry standard crude protein and fiber levels (n = 10/group). Growth performance and diarrhea prevalence were measured alongside gut microbiota composition and metabolites. Pigs fed the HP and HFHP diets had significantly improved feed efficiency compared with both CON and HF diets. Increased protein fermentation, measured through production of biogenic amines, was observed in HP fed animals (P &amp;lt; 0.001). These effects were mitigated by addition of fiber in the HFHP fed pigs. Despite increased markers of protein fermentation, post-weaning diarrhea incidence was not greater in HP fed animals and no increases in gastrointestinal pathogen abundance were detected. Metabolomic and transcriptomic analyses identified critical alterations in host metabolism and cecal transcriptome in the CON compared with the HP fed animals. While all diets were formulated to meet the dietary requirements of weaned pigs, diets with lower protein levels (CON and HF) induced alteration in transcripts from the serine synthesis pathways (P &amp;lt; 0.001) and integrated stress response (P &amp;lt; 0.001) in cecal tissue alongside increases in metabolic pathways related to lysine degradation (P = 0.005). These results challenge the current practice of low protein feeding following weaning by demonstrating a detrimental effect of low protein diets on intestinal cell function and muscle accretion. This suggests that with careful ingredient selection, increased dietary protein post-weaning could better support pig health and performance compared with current industry standard diets.

433 Use of polyclonal antibodies to improve the efficiency of rumen function

Abstract Technologies such as polyclonal antibody preparations (PAP) have been investigated as a tool to improve rumen function, by targeting specific bacteria or molecules. While PAP can be sourced from the serum of immunized mammals, isolating targeted avian-derived antibodies (immunoglobulin Y; IgY) from egg yolk gained popularity due to its reduced impact on hens and greater IgY concentration in yolks. Advantages of avian-derived PAP utilization include cost-effectiveness and convenient production, high stability, and reduced cross-reactivity compared with other PAPs. Furthermore, IgY does not activate the host immune complement system, as observed with PAP derived from mammalian serum. Several proposed strategies explain how PAP might protect the host. It is suggested that PAP can agglutinate bacteria, inhibit bacterial adhesion, suppress bacterial virulence factors, and neutralize toxins. Avian-derived PAP, mainly administered as a direct-fed product in beef and dairy cattle diets, has been studied for its impact on specific rumen microbial populations, especially during high-grain feeding. Research confirms the effectiveness of PAP-IgY in inhibiting the growth of targeted bacteria. In beef steers, feeding PAP-IgY against Streptococcus bovis and Fusobacterium necrophorum resulted in growth inhibition, while IgY against cellulolytic rumen bacteria also showed efficacy in reducing the growth of the targeted strains in vitro. In other studies, PAP-IgY targeting S. bovis and F. necrophorum increased ruminal pH in beef steers and heifers and dairy cows, while also cattle-fed PAP-IgY against F. necrophorum had reduced severity of liver abscesses. When performance was evaluated, PAP-IgY against S. bovis improved feed efficiency of feedlot beef steers, and milk production increased when dairy cows were supplemented with PAP-IgY against lipopolysaccharides, with no observed impact on cow health status. However, not all studies have consistently demonstrated positive effects of PAP-IgY on nutrient digestibility or on mitigating systemic inflammation during high-grain feeding. A recent study revealed that supplementation with PAP-IgY against Methanobrevibacter ruminantium M1 decreased methane output ex-situ and tended to increase molar proportion of propionate in beef steers. In summary, polyclonal antibody preparations, particularly avian-derived IgY, offer a promising alternative to improve rumen function and animal performance. This is evidenced by increased ruminal pH during high grain feeding, inhibition of targeted bacterial growth, and, most recently, methane reduction. However, not all studies demonstrate consistent effects regarding nutrient digestibility. Further research is needed to refine recommendations, including dosage and antibody combinations, and to explore the broader impacts of PAP-IgY supplementation on ruminal and systemic variables to optimize livestock performance.

191 Awardee Talk: Characterizing biological processes influencing the efficiency of nutrient utilization in growing cattle

Abstract 2Abstract: Residual feed intake (RFI), a metric of feed efficiency, is moderately heritable and minimally associated with body size and productivity, making it an ideal trait for investigation as a selection criterion to improve feed efficiency of growing cattle. The objective of this research was to characterize the inter-animal variation in biological processes of growing cattle selected to be divergent in RFI. Holstein heifers [n = 55; body weight (BW) = 351 ± 64 kg) with low- (n = 29) or high- (n = 26) genomically enhanced RFI (RFIg) were selected from a contemporary group of 453 heifers. Heifers were assigned to 1 of 2 pens, equipped with electronic feed bunks and a GreenFeed gaseous-exchange measurement system. Individual dry matter intake (DMI) and feeding behavior data were collected for 84-d. Body weight was measured weekly, and spot fecal samples collected at weighing. Phenotypic RFI (RFIp) was calculated as the residual from regression of DMI on ADG and mid-test BW0.75. On d 70 of the study a rumen fluid sample was collected via esophageal tubing. Blood samples were collected and analyzed for complete blood count (CBC). A mixed model including the fixed effect of RFIg classification and random effect of pen was used to evaluate the effect of RFIg classification on response variables. There were no differences (P &amp;gt; 0.05) in BW and ADG for heifers with divergent RFIg; however, low RFIg heifers consumed 7.5% less (P &amp;lt; 0.05) feed per day. Consequently, low RFIg heifers exhibited a more favorable (P &amp;lt; 0.05) RFIp (-0.188 vs 0.211 kg/d, respectively). Low RFIg heifers exhibited more favorable feeding behavior, with 8.7% fewer (P &amp;lt; 0.05) bunk visit events per day and an 11.2% slower (P ≤ 0.05) eating rate. Low RFIg heifers had 12.5% greater (P &amp;lt; 0.05) total rumen volatile fatty acid concentrations than high RFIg heifers, indicating potentially enhanced microbial fermentation and improved efficiency of feed utilization. Low RFIg heifers had 8.2% less (P &amp;lt; 0.05) methane emissions (g/d), 6.3% less (P &amp;lt; 0.05) carbon dioxide production (g/d), and 6.1% less (P &amp;lt; 0.05) heat production (Mcal/d) calculated according to Brouwer (1965) than high RFIg heifers. Dry matter digestibility did not differ (P &amp;gt; 0.05) between heifers with divergent RFIg. Overall, heifers selected to be more feed efficient exhibited more favorable energy efficiencies and feed efficiency phenotypes. To quantify the variation in RFIg explained by feeding behavior, gas flux, digestibility and rumen fermentation, and CBC partial least squares regression models were developed. Feeding behavior accounted for the largest proportion of variation in RFIg (28.8%). Upon sequential addition of gas flux, digestibility and rumen fermentation, and CBC to feeding behavior, 56.3% of the variation in RFIg was accounted for. Identifying the magnitude at which metabolic processes influence inter-animal variation in efficiency of nutrient utilization provides opportunities to discover valuable candidate biomarkers for selection of more feed efficient cattle.

399 Effect of feeding palm oil products on finishing cattle performance, carcass characteristics, and methane production

Abstract The objectives of this experiment were to evaluate feeding palm oil products on feedlot cattle performance and methane production. Steers (n = 320; 380 ± 14.5 kg) were allocated to 40 pens in a randomized block design and assigned to 1 of 5 treatments consisting of different sources of supplemental fat: 1) No Oil; negative control containing 0.0% supplemental fat, 2) Corn Oil; positive control containing 4.0% supplemental corn oil, 3) Whole Palm; 4.0% supplemental whole palm oil, 4) Olein; 4.0% supplemental palm olein oil, or 5) Stearin; 4.0% supplemental palm stearin oil. Cattle consuming Corn Oil, Olein and Stearin all had greater (P = 0.04) final body weight (BW) and hot carcass weight (HCW) than cattle consuming no oil but were not different (P &amp;gt; 0.11) from each other or from Whole Palm, which was intermediate. Dry matter intake (DMI) of cattle consuming No Oil, Whole Palm and Stearin oil was not different from each other; however, cattle fed Corn Oil had greater intake than Whole Palm (P = 0.03). Corn Oil, Olein, and Stearin all had greater average daily gain (ADG) than cattle consuming No Oil (P = 0.04) but were not different (P &amp;gt; 0.12) from Whole Palm. Adding fat improved feed efficiency (gain to feed; G:F) as all diets including added fat had greater (P &amp;lt; 0.01) G:F than No Oil. Marbling scores were greater (P = 0.01) for Olein and Stearin than Corn and Whole Palm. There were no differences in backfat, ribeye area or liver abscess rate among any treatments (P &amp;gt; 0.74). Gas emissions were evaluated for only the No Oil and Whole Palm treatments. Total methane and methane produced per pound of dry matter intake was less for cattle consuming Whole Palm than No Oil by 14.8% (P &amp;lt; 0.04) while cattle were in the methane chamber. Methane produced per kilogram of ADG for Whole Palm was also reduced (P &amp;lt; 0.01) by 21.4% compared with No Oil. The results of this study indicate feeding palm oil products as a source of supplemental fat in finishing diets increases final BW, ADG, and HCW compared with feeding no supplemental fat, but had minimal impact on DMI resulting in an improvement in G:F. Adding supplemental fat reduced methane emissions in cattle when feeding Whole Palm compared with No Oil. The value of palm oil products in feedlot finishing diets is comparable with feeding corn oil.

Transcriptomic profiling reveals potential regulatory genes and molecular mechanisms of residual feed intake in Jian carp (Cyprinus carpio var. Jian)

Feed efficiency is one of the most important economic traits in animal production. Improving feed efficiency through genetic selection or other approaches will reduce production costs and mitigate environmental impacts. Residual feed intake (RFI) has some advantages over traditional feed efficiency metrics as a selection criterion for improving feed efficiency, because it is not a ratio and unrelated to growth. In this study, high RFI (HRFI) and low RFI (LRFI) Jian carp (Cyprinus carpio var. Jian) were tested for feed efficiency traits and serum biochemical indices. No significant differences were observed in the growth rates between HRFI and LRFI group, but daily feed intake of LRFI was significantly lower than that of the HRFI group. The results indicated that significantly higher content of triglyceride (TG) and total cholesterol (T-CHO) in the LRFI group was significantly correlated with RFI. We also selected HRFI and LRFI carp for transcriptomic analysis to determine differentially expressed genes (DEGs) in the liver tissues of 12 individuals. A total of 830 DEGs were identified between HRFI and LRFI group, of which 486 genes were up-regulated and 344 genes were down-regulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that DEGs were mainly enriched in fatty acid metabolism, ErbB signaling pathway, phosphatidylinositol signaling system, and autophagy. Lipid metabolism and autophagy-related genes, were considered candidate genes that played a crucial role in regulating feed efficiency. Taken together, these results indicated that differences in RFI affect Jian carp metabolism and cell fate, and that alterations in fatty acid metabolism and autophagy are key physiological modes of regulation in low RFI Jian carp. Our data provide valuable candidate genes and candidate pathways, which will help to study the molecular mechanisms of feed efficiency in carp.

Genetic parameters and genotype-by-environment interaction estimates for growth and feed efficiency related traits in Chinook salmon, Oncorhynchus tshawytscha, reared under low and moderate flow regimes

BackgroundA genotype-by-environment (G × E) interaction is defined as genotypes responding differently to different environments. In salmonids, G × E interactions can occur in different rearing conditions, including changes in salinity or temperature. However, water flow, an important variable that can influence metabolism, has yet to be considered for potential G × E interactions, although water flows differ across production stages. The salmonid industry is now manipulating flow in tanks to improve welfare and production performance, and expanding sea pen farming offshore, where flow dynamics are substantially greater. Therefore, there is a need to test whether G × E interactions occur under low and higher flow regimes to determine if industry should consider modifying their performance evaluation and selection criteria to account for different flow environments. Here, we used genotype-by-sequencing to create a genomic-relationship matrix of 37 Chinook salmon, Oncorhynchus tshawytscha, families to assess possible G × E interactions for production performance under two flow environments: a low flow regime (0.3 body lengths per second; bl s−1) and a moderate flow regime (0.8 bl s−1).ResultsGenetic correlations for the same production performance trait between flow regimes suggest there is minimal evidence of a G × E interaction between the low and moderate flow regimes tested in this study, for Chinook salmon reared from 82.9 ± 16.8 g (x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\overline{\ ext{x}}}$$\\end{document} ± s.d.) to 583.2 ± 117.1 g (x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\overline{\ ext{x}}}$$\\end{document} ± s.d.). Estimates of genetic and phenotypic correlations between traits did not reveal any unfavorable trait correlations for size- (weight and condition factor) and growth-related traits, regardless of the flow regime, but did suggest measuring feed intake would be the preferred approach to improve feed efficiency because of the strong correlations between feed intake and feed efficiency, consistent with previous studies.ConclusionThis new information suggests that Chinook salmon families do not need to be selected separately for performance across different flow regimes. However, further studies are needed to confirm this across a wider range of fish sizes and flows. This information is key for breeding programs to determine if separate evaluation groups are required for different flow regimes that are used for production (e.g., hatchery, post smolt recirculating aquaculture system, or offshore).

Host genetics and gut microbiota synergistically regulate feed utilization in egg-type chickens

BackgroundFeed efficiency is a crucial economic trait in poultry industry. Both host genetics and gut microbiota influence feed efficiency. However, the associations between gut microbiota and host genetics, as well as their combined contributions to feed efficiency in laying hens during the late laying period, remain largely unclear.MethodsIn total, 686 laying hens were used for whole-genome resequencing and liver transcriptome sequencing. 16S rRNA gene sequencing was conducted on gut chyme (duodenum, jejunum, ileum, and cecum) and fecal samples from 705 individuals. Bioinformatic analysis was performed by integrating the genome, transcriptome, and microbiome to screen for key genetic variations, genes, and gut microbiota associated with feed efficiency.ResultsThe heritability of feed conversion ratio (FCR) and residual feed intake (RFI) was determined to be 0.28 and 0.48, respectively. The ileal and fecal microbiota accounted for 15% and 10% of the FCR variance, while the jejunal, cecal, and fecal microbiota accounted for 20%, 11%, and 10% of the RFI variance. Through SMR analysis based on summary data from liver eQTL mapping and GWAS, we further identified four protein-coding genes, SUCLA2, TNFSF13B, SERTM1, and MARVELD3, that influence feed efficiency in laying hens. The SUCLA2 and TNFSF13B genes were significantly associated with SNP 1:25664581 and SNP rs312433097, respectively. SERTM1 showed significant associations with rs730958360 and 1:33542680 and is a potential causal gene associated with the abundance of Corynebacteriaceae in feces. MARVELD3 was significantly associated with the 1:135348198 and was significantly correlated with the abundance of Enterococcus in ileum. Specifically, a lower abundance of Enterococcus in ileum and a higher abundance of Corynebacteriaceae in feces were associated with better feed efficiency.ConclusionsThis study confirms that both host genetics and gut microbiota can drive variations in feed efficiency. A small portion of the gut microbiota often interacts with host genes, collectively enhancing feed efficiency. Therefore, targeting both the gut microbiota and host genetic variation by supporting more efficient taxa and selective breeding could improve feed efficiency in laying hens during the late laying period.

PEMBERDAYAAN MASYARAKAT MELALUI PENERAPAN ALAT PEMBERI PAKAN IKAN OTOMATIS DENGAN TENAGA PANEL SURYA BERBASIS IOT

This community service activity aims to develop and implement an automatic fish feeder based on IoT and solar panel power in Cikolelet Village, Cinangka District, Serang Regency. This tool is designed to improve feeding efficiency and productivity of fish farmers by utilizing renewable technology. The service process includes prototype design, installation, and evaluation of tool performance in the field. The implementation results show that this tool is able to provide feed automatically and regularly, making it easier for fish farmers to manage their aquaculture. Follow-up assistance and maintenance are carried out to ensure the tool continues to function properly and provide long-term benefits. This initiative is expected to provide practical and sustainable solutions for fish farmers and promote the utilization of modern technology in local communities.

PSI-27 Dietary supplementation of betaine and an antioxidant blend improved feed efficiency in commercially housed fattening pigs under heat stress conditions

PSI-27 Dietary supplementation of betaine and an antioxidant blend improved feed efficiency in commercially housed fattening pigs under heat stress conditions

Alleviating effects of guar gum on high-fat diet-induced liver injury in common carp (Cyprinus carpio)

This research aimed to determine the effect of dietary guar gum inclusion in high-lipid diets on the liver health of common carp (Cyprinus carpio). Four high-fat diets (10 % crude lipid) containing 0 % (HF), 0.3 % (HFG0.3), 1 % (HFG1), and 3 % (HFG3) of guar gum and a normal-lipid diet (5 % crude lipid; Control) were formulated. The tested diets were evenly and randomly distributed to fifteen tanks, with each tank containing thirty fish (4.53 ± 0.05 g). Fish were fed until apparent satiation for eight weeks. Compared to HF, diets HFG0.3, HFG1, and HFG3 significantly improved feed efficiency, with the HFG0.3 diet enhancing weight gain rate and specific growth rate. The results indicated that HF induced gut dysbiosis, hepatic lipid accumulation, oxidative stress, inflammation, and disturbance in hepatic lipid and cholesterol metabolism. Compared to the HF diet, diets HFG0.3, HFG1, and HFG3 substantially decreased hepatic lipid accumulation and malonaldehyde content, increased catalase activity and the expression of AMP-activated protein kinase (AMPKα2), peroxisomal proliferator-activated receptor alpha (PPARα), cholesterol 7alpha-hydroxylase, and decreased the expression of interleukin-1β (IL-1β). Moreover, the HFG0.3 and HFG1 diets dramatically increased nuclear factor erythroid 2-related factor 2 and liver X receptor expression and decreased protein carbonyl contents and expression of IL-8, nuclear factor kappa B (NF-κB p65), and tumor necrosis factor α. Furthermore, the HFG1 diet significantly increased carnitine palmitoyltransferase 1 and peroxisomal proliferator-activated receptor gamma coactivator 1 expression and reduced expression levels of fibroblast growth factor 19, farnesoid X receptor, and sterol regulatory element-binding protein type 1. The linear discriminant analysis effect size (LEfSe) analysis showed that HFG 0.3 and HFG1 substantially increased the enrichment of beneficial microbiota (e.g., lactic acid bacteria, Cetobacterium, and Fusobacterial) and decreased the enrichment of harmful microbiota (e.g., Proteobacteria, Acinetobacter, and Pseudomonas) compared to HF. These results suggested that guar gum can mitigate high-fat diet-induced liver damage in fish.