bluuebunny/crossref_metadata_2025 huggingface dataset:
433 Use of polyclonal antibodies to improve the efficiency of rumen function
Authors: da Silva Gleise Medeiros
Published: September 2024

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.
223 Exploring the relationship between corn grain yield and residue quantity and quality
Authors: Drewnoski Mary E , Wheeler Kaylee , Miller Jessica , Ference Sadie , Parsons Jay , Easterly Amanda , Redfearn Daren
Published: September 2024

Corn residue grazing is an economical winter feed resource for cows in the Midwest. However, questions about changes in the feeding value have been raised. A 2-yr experiment was conducted to evaluate the effects of corn grain yield on the quantity and quality of corn residue. In yr 1, 32 hybrids were evaluated from four locations in Nebraska. In yr 2, 31 hybrids were evaluated from three locations in Nebraska. Each hybrid was harvested from four replicate plots. Three of the locations were irrigated and four were rainfed. Observed grain yields ranged from 1,416 to 22,318 kg/ha (23 to 355 bushels/acre) with a mean of 12,704 kg/ha (202 bushels/acre). As corn yield increased, the amount of grain relative to whole plant biomass (harvest index) increased (P < 0.01). Harvest index ranged from 48.4% to 67.6% and averaged 59.3%. The increase in harvest index indicates there was less residue produced per kilogram of corn grain produced in greater yielding corn. However, as expected, total amount of residue (kg/ha) still increased (P < 0.01) as grain yield (kg/ha) increased. Within the residue, the proportions of leaf and husk increased (P < 0.01) slightly, stalk decreased (P < 0.01) slightly, while the proportion of cob did not change (P = 0.62) as grain yield increased. On average, the observed plant proportions in this experiment were 15.8% husk, 18.6% leaf, 50.5% stalk and 15.1% cob (DM basis). As grain yield increased, the proportion of husk within residue increased from 14 to 21% and leaf increased from 17 to 24%. In contrast, the proportion of stalk within residue decreased from 53 to 41%. Cattle primarily consume leaf and husk when grazing corn residue, thus the availability and digestibility of those plant parts could be a key factor that affects diet quality of grazing cattle. Both the digestible organic matter (DOM, % of DM) in leaf and husk and the kilograms of DOM from leaf plus husk per 25.4 kilograms of grain declined (P < 0.01) as grain yield increased. On average, the DOM (% of DM) for husk was 69.3% but declined from 83.6 to 56.4% with increasing in grain yield. The average DOM (% of DM) for leaf was 55.6% and declined from 65.3 to 41.6% as grain yield increased. The average amount of DOM from leaf plus husk was 3.6 kg/25.4 kg of grain (8 lb/bushel) and declined from 5.8 to 2.5 kg/25.4 kg of grain (12.8 to 5.5 lb/bushel) as grain yield increased. Thus, the concentration of nutrients in corn residue declined as grain yield increased, meaning greater yielding corn had reduced quality residue. The impacts of this decline in diet quality on cow performance should be further evaluated.
224 Yield and nutritive values of a polycrop and annual cereal monoculture used in winter swath grazing
Authors: Obiora Somtochukwu , Lardner H (Bart) A , Nowosad Janet , Oyedeji Oluwatobi , Vandenberg Carien , Larson Kathy A , Kelln Breeanna , Durunna Obioha N
Published: September 2024

This 3-yr study evaluated a comparative biomass yield and nutritive values of 2 forage systems: 1) a cereal monoculture (CDC-SO1 oats) and 2) a polycrops (PC) consisting of oat, brassicas (turnip and rape) and forage pea (4010) harvested at the hard dough (HD) stage for winter swath grazing purpose. A 12-ha field was divided into six, 2-ha paddocks, where each paddock was randomly assigned to 1 of 2 replicated (n = 3) forage systems. Forages were seeded in June and sampled for biomass yield and nutritive value at the soft dough (SD) and HD stages of oats. The seeding rate of oat monoculture (OM) was 157 kg/ha, while the PC was 45 kg/ha (oat), 11 kg/ha (forage pea) and 6 kg/ha (brassica). Forage samples were collected from a 0.6 m2 area at 24 pre-selected GPS points (4 per paddock), weighed and then oven-dried to a constant weight to determine DM yield. Data were analyzed using the PROC MIXED procedure of SAS and included treatment effects and treatments × stage interactions. Year was treated as a random effect due to climatic variations across years. For OM, there was a significant difference (P = 0.03) in biomass yield between SD (7,762.7 ± 1,217.9 kg/ha) and HD (8,902.8 ± 1,217.9 kg/ha) stages, while PC biomass yield did not differ (P = 0.94) between SD (5,922.4 ± 1,217.9 kg/ha) and HD (6,163.1±1,217.9 kg/ha) stages. The biomass yields between the two forage systems were different (P < 0.05) at the SD and HD stages. Crude protein (CP) concentration did not differ (P > 0.05) between the OM and PC at SD (10.4 vs 10.3%) and HD (8.9 vs 9.6%) stages. At the SD stage, significant differences (P < 0.05) between OM and the PC were observed for neutral detergent fiber (NDF, 50.9 vs 44.1%), calcium (0.2 vs 0.5%), phosphorus (0.2 vs 0.3%), and RFV-relative feed value (120.3 vs 142.2). Similarly, the starch (20.9 vs 16.5%), calcium (0.2 vs 0.5%), and phosphorus (0.2 vs 0.3%) values for OM and PC, respectively, also differed (P < 0.05) at the HD stage. Differences (P < 0.05) were observed between the SD and HD stages of OM for acid detergent fiber (ADF, 30.1 vs 27.0%), total digestible nutrient (TDN, 65.4 vs 67.9%), and starch (14.9 vs 20.9%) content, respectively. Study results suggest that swathing OM at the HD stage would be beneficial in terms of greater biomass yield without compromising quality, while PC can be harvested at either SD or HD stages based on the annual cereal component. Also, the lack of significant difference in the RFV, CP and TDN values between the PC and OM at the HD stage suggests that PC could be a viable alternative forage system for winter swath grazing.
396 Effects of allocation timing on cattle performance and forage utilization when swath grazing a sorghum-sudangrass hybrid in eastern Nebraska
Authors: Aquino Thomas , Drewnoski Mary E , Fernandes Pedro Henrique Jota
Published: September 2024

Swath, or windrow, grazing is the process of cutting hay, leaving it in windrows, and allowing cattle to graze these windrows in the winter. This grazing system reduces winter feeding costs by mitigating the need to bale and transport hay, while having the potential for increased utilization compared with grazing the forage standing. This study aimed to determine the effect of varying allocation timing on cattle performance and forage utilization. A sorghum-sudangrass hybrid (Sorghum× drummondii) was planted in June 2023, cut in early November, and grazed from mid-November 2023 to mid-January 2024. A 16-ha field was divided based on seeding rate with one-half seeded at the recommended rate of 39.2 kg/ha (REC) and one-half with a double rate of 78.4 kg/ha (DOU). The field was subdivided into a total of 8 paddocks (4 per seeding rate) with either 10 (n = 4) or 11 (n = 4) windrows. Forage was cut and windrows were gathered from a 4.57 m width in the field. Prior to grazing, a 0.30 m length of three swaths in each paddock was sampled to determine initial forage mass. A total of 60 steers [initial body weight (BW) = 240 ± 8.3 kg] were stratified by BW and assigned to one of 8 paddocks (n = 7 or 8 calves) to result in equal BW per swathed area. Allocations were offered in full once-per week (1X) or, one-half of the total forage was allocated twice weekly (2X). Post-graze samples were collected to estimate utilization and allocation amount was adjusted as needed based on visual appraisal of post grazing biomass. Cattle were pulled from the field due to snow cover after a 64-d grazing period. The area grazed was used to calculate the animal unit months/ha (AUM) achieved for each paddock. Pre-grazing forage mass did not differ between allocation timing (P = 0.89) or among seeding rates (P = 0.10; REC = 6,720 ± 545 kg/ha, DOU = 8,534.0 ± 545 kg/ha). There was an allocation timing by seeding rate interaction (P < 0.01) for forage offered with 1X (10.62 kgּ steer-1ּ d-1) being offered more (P < 0.01) than 2X (8.43 kg/steer/d) within REC, but no difference (P = 0.31) in forage offered due to allocation within DOU (8.31 kgּ steer-1ּ d-1). However, post grazing biomass (P = 0.35) and utilization (59 ± 8%) were not affected by allocation timing (P = 0.48). Average daily gain (ADG) also did not differ (P = 0.93) due to allocation timing (0.20 ± 0.07 kg). Most notably, there was a significant allocation effect (P = 0.05) on AUM/ha with 1X (14.51 ± 1.00) being lesser than 2X (16.82 ± 1.00). However, there was no significant difference (P = 0.30) in forage disappearance (291 ± 61 kg/AUM) due to allocation timing. This indicates that more frequent allocations can lead to increased carrying capacity. Increasing the frequency of allocation is a simple management practice producers can implement when swath grazing sorghum-sudangrass to increase carrying capacity.
397 Effect of corn harvest with a chopping head on performance of cattle grazing corn residue
Authors: Biehler Connor K , Davies-Jenkins Shelby L , Aquino Thomas , Lorences Sofia Suarez , McDermott Rebecca L , MacDonald James C , Drewnoski Mary E
Published: September 2024

The addition of stalk chopping equipment on combine heads has become more common. An advantage of grazing residue compared with baling, is the ability of cattle to select the more digestible plant parts (husk and leaf). Chopping may impact this ability and decrease the feeding value. Thus, this study was designed to evaluate the effects of chopping residue at harvest on grazing cattle performance. A cornfield (16 Mg grain/ha) was divided into 12 paddocks blocked by location within field and assigned randomly to be harvested using a chopping or non-chopping combine head, with 4 paddocks assigned to be grazed (1.05 ha) from each harvest method (HM) and 4 ungrazed. Growing steers [n = 40; body weight (BW) = 230 ± 3.5 kg] were stratified by BW and assigned randomly to a grazed paddock, with 6 steers in the west block and 4 steers in the east block, with 1 rumen canulated steer (484 ± 33 kg BW) being assigned to each of the east paddocks and used as diet samplers. This resulted in the same grazing pressure (2.9 animal units/ha) in grazed paddocks. Cattle were supplemented at 0.6 % of initial BW with a distillers dried grains plus solubles and mineral mix daily. Cattle grazed for 56 d resulting in 5.4 Animal Units Months/ha. Residue mass of three 0.58 m2 frames was sampled in each paddock before (d -1), during (d 36) and after grazing. Husks were collected from three 5.81 m2 areas per paddock at each of the three timepoints. For residue mass, there was a significant (P < 0.01) HM by time interaction. There was no difference (P = 0.34) in residue mass between HM prior to grazing. However, at 36 d into grazing, residue mass of standard was greater (P = 0.03) than chopped, and post-grazing residue mass of chopped was greater (P = 0.01) than standard. When husk (kg/ha) was evaluated, there was a significant (P < 0.01) HM by time by grazing interaction. Prior to grazing, there was no difference (P ≥ 0.66) in husk between the grazed and ungrazed paddocks within HM. However, husk was less (P < 0.01) for chopped than standard. On d 36, within HM, grazed had less (P < 0.01) husk than the ungrazed. However, within grazing status on d 36 there was no effect (P ≥ 0.52) of HM. Post-grazing there were no differences (P ≥ 0.19) in husk among treatments. Within grazed treatments there was greater (P < 0.01) husk prior to grazing initiation compared with both D36 and post-grazing which did not differ (P ≤ 0.85). Within ungrazed treatments, pre-grazing and D36 did not differ (P ≥ 0.10) in husk, however, husk was lesser (P > 0.01) at the post-grazing sampling. For ADG there was no difference (P = 0.20) between HM, with 0.37 and 0.31kg/d for standard and chopped, respectively. Overall, HM had no effect on grazing cattle performance.
281 Changes in satellite cell number in maternal and fetal muscle with 5-hydroxy tryptophan supplementation during late gestation
Authors: Udoka Aliute Nkoyo S , Iheanacho Gabriella , Worley Grayson , Klotz James L , Duckett Susan K
Published: September 2024

Toxic tall fescue contains ergot alkaloids, which induce vasoconstriction in livestock, leading to fescue toxicosis. This condition can impact muscle development due to altered blood flow. Supplementation with 5-HTP may counteract the vasoconstrictive effects of fescue alkaloids. We aimed to investigate the influence of 5-HTP supplementation on satellite cells, myoblast, and preadipocyte numbers in maternal and fetal muscle during late gestation in Suffolk ewes. We hypothesized that 5-HTP supplementation would mitigate the effects of fescue toxicosis on muscle cell populations, potentially promoting muscle development and regeneration in maternal and fetal tissues. Suffolk ewes (n = 75), naïve to toxic tall fescue, were blocked by body condition score and body weight into 10 groups for synchronization. Ewes were confirmed pregnant using transabdominal ultrasound, and lamb number was estimated at gestational day (gd) 60. Pregnant ewes carrying twins (n = 30) were randomly assigned to one of three treatments: 1) negative control (CON, n = 10), 2) toxic tall fescue seed containing 1.77 mg ewe-1ּ d-1 ergovaline/ergovalinine plus 5-HTP (2.5 mg/kg BW) supplement (5HTP, n = 10), or 3) positive control, fed toxic tall fescue seed containing 1.77 mg ewe-1ּ d-1 ergovaline/ergovalinine (E+, n = 10). Ewes were individually fed a total mixed ration from gd 78 to gd 85 of pregnancy and then TMR plus treatment (CON, E+ or 5HTP) from gd 86 to d 111. On gd 112, terminal necropsies were performed, and semimembranosus muscle (SM) from the ewe and fetus was removed. Weights were obtained, and then samples were digested using pronase (1.5mg/mL) to isolate preadipocyte (PP1), myoblasts (PP2) and satellite cell (PP3) fractions using a pre-plating technique. Cells were quantified using a Neubauer-hemocytometer and trypan blue to also assess cell viability and changes in cell number. Fetal SM had a greater (P < 0.05) number of pre-adipocytes, myoblasts, and satellite cells per gram of tissue digested in comparison with the ewes. Pre-adipocyte and myoblast number per gram of tissue digested did not differ (P > 0.05) by treatment. The 5HTP group had the greater (P < 0.05) number of satellite cells per gram of tissue digested in comparison with the CON group. Satellite cell numbers tended (P < 0.10) to be greater in the 5HTP group in comparison to the E+ group. Satellite cell numbers from CON and E+ treatment groups did not differ (P > 0.05). In conclusion, 5-HTP supplementation during late gestation in Suffolk ewes exposed to toxic tall fescue significantly increased satellite cell numbers in maternal and fetal muscle tissues. This suggests a potential mitigation of the impact of fescue toxicosis on muscle cell populations.
427 Impact of late gestation slow-release nitrogen-enriched diets on energy metabolism in calf skeletal muscle: A proteomic and transcriptomic approach
Authors: Gionbelli Mateus P , Costa Thais C , Cediel-Devia Diana C , Nascimento Karolina B , Gionbelli Tathyane R S , Duarte Marcio S
Published: September 2024

The current study aimed to determine the enriched biological processes, through proteomic and transcriptomic data, associated with maternal slow-release nitrogen diets received during late gestation and their effects on the skeletal muscle of offspring. From d 180 to d 268 of gestation, a total of 16 pregnant Brahman cows were divided into two groups: a control (CON, n = 12) low crude protein (CP) basal diet (6% of CP, ad libitum) plus mineral mixture (130 gּ cow-1ּ d-1), or the CON treatment supplemented with a slow-released N (SRN, n = 9) based protein concentrate supplement [40% CP, fed 2 g/kg of body weight (BW)/d in the morning) composed by corn, soybean meal, urea and a SRN source (Timafeed Boost, Roullier Group, Saint-Malo, France). Muscle biopsies were performed on d 45 of age in calves for RNA sequencing (RNA-seq) and proteomic (HPLC-MS/MS) analyses. The quality control of RNAseq raw data was assessed using FASTQc software, with low-quality reads trimmed by Trimmomatic. Reads were mapped against the Bos taurus reference genome using STAR. Differentially expressed (DE) genes and isoforms, significant at an adjusted P-value ≤ 0.05, were identified using the limma package and Cuffdiff tool, respectively, in the R environment. Proteomic data was processed in MaxQuant against the Bos taurus reference proteome, with statistical analysis performed using the MSqRob package in R. Network analyses identified significant biological processes (adjusted P-value ≤ 0.05) among differentially abundant proteins (DAPs). Notably, while the experimental treatment did not affect transcript abundance, protein-level differences were observed. Enriched biological processes in SRN group skeletal muscle of calves included acetyl-CoA biosynthesis from pyruvate, mitochondrial respiratory chain complex assembly, regulation of calcium ion transmembrane transport, and several others related to energy and nitrogen metabolism. Protein-protein interaction network analyses revealed key processes such as ATP and glucose metabolism, tricarboxylic acid cycle, and sarcomere organization. Overall, our findings underscore the beneficial impact of slow-release nitrogen-enriched diets during late gestation on energy metabolism in calf skeletal muscle.
429 Maternal rate of gain and one-carbon metabolites supplementation alters the gene expression profile of fetal brain during early gestation in beef heifers
Authors: Anas Muhammad , Ward Alison K , Da Diniz Wellison Jarles Silva , King Layla E , Syring Jessica G , Entzie Yssi L , Hirchert Mara R , Borowicz Pawel P P , Crouse Matt S , Reynolds Lawrence P P , Dahlen Carl R , Caton Joel S S
Published: September 2024

Maternal nutritional plane during pregnancy may leave lifelong impacts on offspring in beef cattle. Given that, we hypothesized that the supplementation of one-carbon metabolites (OCM) during pregnancy would mitigate the negative effects of maternal rate of gain through brain gene expression regulation in early developing bovine fetuses. The objective of this study was to evaluate the effects of OCM supplementation and maternal rate of gain on gene expression in the developing fetal brain in gestating beef heifers. Herein, Angus crossbred heifers (n = 72, body weight = 406 ± 33 kg) were randomly assigned to 2 × 2 factorial arrangement of treatments with two levels of maternal rate of gain (CON, 0.60 kg/d; and RES, -0.23 kg/d) each with or without OCM supplementation (+OCM, and -OCM). Heifers were fed individually and were bred using female-sexed semen from a single sire. The OCM supplementation included rumen-protected choline (44.4 g/d) and methionine (7.4 g/d) in corn carrier fed daily and weekly injections of folate (320 mg) and vitamin B12 (20 mg). The -OCM heifers received the corn carrier and saline injections. The treatments started at the time of breeding and continued until d 63 of gestation when pregnant heifers (n = 29) were slaughtered to collect fetal brain tissues for RNA sequencing. The fetal brain phenotypic data were analyzed using MIXED procedures of SAS, indicating that restricted nutrition affected the fetal right hemisphere weight (P < 0.05), and there was a strong tendency for overall fetal brain weight (0.05 < P < 0.1) to be affected as well. Brain transcriptomics data were analyzed using STAR aligner and a total of 177 differentially expressed genes (DEGs, FDR < 0.05) were identified across all treatment comparisons using DESeq2. Most of the DEGs were either isoforms of spliceosomal non-coding RNAs or micro-RNAs (miRNAs) associated with biological processes (FDR < 0.1) like mRNA processing, cellular nitrogen metabolism, lipid metabolism, and post-transcriptional gene silencing. The key miRNAs upregulated in the brain tissue of restricted fetuses without OCM supplementation, bta-mir-2375, bta-mir-876, and bta-mir-196a-1, were found to be associated with early embryogenesis and essential cellular regulatory processes. Conversely, in restricted fetuses with OCM supplementation, upregulated miRNAs such as bta-mir-216b, bta-mir-2285dd, and bta-mir-1298 were linked to early embryonic development, muscular development, and lipid metabolism in cattle. Both phenotypic and transcriptomics data here revealed that the maternal rate of gain altered fetal brain development, with differences seemingly compensated by OCM supplementation. USDA is an equal opportunity provider and employer.
428 Influence of melatonin supplementation in pregnant multiparous crossbred beef cows grazing endophyte-infected tall fescue on dam weight, milk yield, and pre-weaning growth of steer calves
Authors: Snider Miriam A , Hopkins Carson R , Moss Nathaniel T , Looney Charles R , Powell Jeremy G , Kegley Elizabeth B , Coffey Ken P , Gadberry M Shane , Meyer Allison M , Lemley Caleb O , Littlejohn Brittni P
Published: September 2024

The objective was to evaluate the influence of melatonin supplementation in pregnant beef cattle grazing toxic, endophyte-infected tall fescue (E+) on post-calving dam body weight (BW), milk production, and preweaning growth of steer calves. Multiparous cows were artificially inseminated with sex-sorted semen (Y chromosome-bearing sperm) from a single Red Angus sire and maintained on pastures free from E+ fescue prior to the start of the treatment period. Pregnant cows were assigned to one of three treatment groups with two replications per treatment: non-toxic, novel endophyte-infected (NE+) tall fescue without melatonin supplementation (NE+/NM; n = 15), E+ fescue with melatonin supplementation (E+/M; n = 16), and E+ fescue without melatonin supplementation (E+/NM; n = 18). The treatment period was over 70 d between May and July (d 147 ± 1 to 217 ± 1 of gestation). A commercially available feed was mixed with melatonin (100 µg/kg BW) or without melatonin and hand-fed to each cow daily. At the conclusion of the treatment period (56 ± 18 d before parturition), cattle were moved to a single group and maintained on pastures free from E+ fescue for the remainder of the study. Dams and steer calves were weighed at d 0, 28, 56, 84, 112, 140, and 168 relative to calving (d 0 = calving). Four-hour milk yields on d 28 ± 3 and d 56 ± 3 were used to estimate daily milk volume and weight. Dam and calf BW were analyzed using the MIXED procedure of SAS specific for repeated measures with treatment, time, and the interaction as fixed effects and replicate as random. Calf birth weight, dam milk volume, and dam milk weight were analyzed using the MIXED procedure of SAS with treatment as a fixed effect and replicate as random. On d 28, estimated daily milk volume and weight were decreased (P < 0.05) in E+/NM dams relative to NE+/NM dams. On d 56, estimated daily milk volume and weight were decreased (P < 0.03) in E+/NM and E+/M dams relative to NE+/NM dams. There was an effect of time for dam and calf weights (P < 0.01). There was a treatment by time interaction for calf body weight, with calves born to E+/NM dams having decreased body weight relative to calves born to NE+/NM and E+/M dams from d 112 to d 168 (P = 0.02). There were no other effects of treatment, time, or the interaction (P > 0.05). These data suggest melatonin supplemented to pregnant crossbred multiparous beef cows grazing endophyte-infected tall fescue during mid-late gestation may increase preweaning growth of steer calves.
172 Impact of maternal and postnatal 25-hydroxycholecalciferol supplementation on porcine and avian satellite cell mitotic activity and skeletal muscle growth characteristics
Authors: Starkey Jessica D
Published: September 2024

Vitamin D is an essential micronutrient most well-known for regulating calcium and phosphorus homeostasis and bone mineralization. However, over the last 20 yr, the extra-skeletal, pleotropic effects of vitamin D and its metabolites have gained greater attention. For livestock species reared indoors, vitamin D supplementation is especially important and commonly achieved by dietary addition of cholecalciferol, also known as vitamin D3 (D3). Cholecalciferol is hydroxylated in the liver to produce the circulating form, 25-hydroxycholecalciferol (25OHD3), also called calcidiol. Circulating 25OHD3 is subsequently converted to 1α,25-hydroxycholecalciferol (1,25OHD3) which binds a nuclear receptor found in many tissues, including skeletal muscle, to elicit its effects. This presentation will focus on the recent work regarding the effects of both maternal and postnatal 25OHD3 supplementation on porcine and avian satellite cell mitotic activity and skeletal muscle growth characteristics. Feeding broilers 25OHD3 posthatch results in a satellite cell-mediated skeletal muscle hypertrophic response in the fast-twitch pectoralis major but not the slow-twitch biceps femoris. Maternal dietary supplementation of gilts and hens with 25OHD3 in place of the majority of D3 increases circulating 25OHD3 concentrations in both dams and their offspring. The improvements in vitamin D status coincide with positive effects on skeletal muscle fiber number in fetal piglets as well as satellite cell mitotic activity and hypertrophic growth of fibers in both swine and broiler chickens. Though, interestingly, combining maternal and posthatch 25OHD3 supplementation in broilers does not appear to produce additive or synergistic effects on SC-mediated muscle growth. However, increasing circulating concentrations of 25OHD3 by supplementing either the maternal or postnatal diet with 25OHD3 has positive effects on meat yield in both porcine and avian models. Overall, these data shed light on the cellular mechanisms behind the efficacy of this vitamin D supplementation strategy using commercially available 25OHD3 sources in increasing meat yield and yet, leaves enough unanswered questions remaining to warrant further exploration.
56 Establishing grain-based modified protocols for the nutritional and physical reconditioning of malnourished horses
Authors: Bardassi Ariane Tabari , Boyd Jamie A , Santos Hugo , Dodson Zach A , Rosa Laura Patterson
Published: September 2024

From April to June 2023, we conducted a study to evaluate the effects of Total Equine containing Ascophyllum nodosum seaweed and chelated minerals on the continued recovery and reconditioning of 10 horses. Horses were used on a preceding 8-wk study and given a 21-d, 24-h turnout, with ad libitum access to Bermuda hay washout period between trials. Once the washout was complete horses were randomly assigned to one of three diets: Control (Ctrl) - a commercial grain product and Bermuda hay (n = 3); Treatment (Trt) - Total Equine and Bermuda hay (n = 4); and Grain only (Grn) - Total Equine without Bermuda hay (n = 3); for 8 wk with ad libitum access to water. For Ctrl and Trt diets we offered hay twice a day in port-a-gazer tubs to control waste, adjusted daily for a 3% refusal rate, and orts were collected twice a day. Individuals were weighed weekly, and their body condition score (BCS) was evaluated during the standardization period, wk 4 and wk 8. Grain was offered at a rate of 0.005% BW + 227 kg and divided into 2 equal feedings for Ctrl and Trt diets, while for the Grn diet horses were offered up to 9.07 kg of grain divided into 3 daily feedings, with grain amounts adjusted weekly based on BW. For physical reconditioning, horses were exercised 5 d/wk with a Priefert hot walker, increased in duration and intensity from wk 1 to 8. We collected samples of grain, hay, and orts for DM, NDF, ADF, EE, CP, and ash analysis. Blood samples were collected at wk 0, 4, and 8 for analysis. Baseline health parameters as rectal temperature, heart, and respiratory rate were measured weekly throughout the study to evaluate possible detrimental effects of the trial. Data were analyzed using Proc Mixed procedures in SAS. Investigation into Dry matter intake (DMI) between the Ctrl and Trt cohorts revealed no significant difference. However, significant differences (P ≤ 0.05) were observed in Overall DMI (grain + hay) among Grn and other diet pairs. Significant average daily gain (ADG) and Efficiency (EFF) observations in wk 1, 4, and 6 (P ≤ 0.05) suggest that Total Equine grain had better overall performance in both groups during the first 6 wk of the trial compared with the Ctrl grain. Our results demonstrate the successful outcome of a modified, grain-based protocol in nutritional and physical reconditioning of a cohort of malnourished horses. Further evaluation of larger populations is still needed.
146 The effects of antimicrobials and antimicrobial associated diarrhea on the fecal microbiome of the horse
Authors: Arnold Carolyn E
Published: September 2024

Antibiotics are commonly given to horses to treat known bacterial infections or as prophylaxis against the development of infection. Diarrhea is a recognized adverse effect of antimicrobial administration in horses (antimicrobial associated diarrhea, AAD). In veterinary referral centers, AAD has a reported incidence of 22 to 94% (McGorum, 2010), while horses with AAD are 4.5 times more likely to die compared with horses with other types of colitis (Woods and Cohen, 1999). Although all antibiotics have potential to induce diarrhea, some have increased risk due to low oral absorption, biliary excretion, or enterohepatic recycling. The role of dysbiosis in the gut microbiota is a key feature in the pathogenesis of AAD. Disruption of commensal bacteria of the hindgut allows for pathogen overgrowth and alteration in microbial metabolic function. To date, 16S rRNA sequencing has been used to characterize the effects of penicillin, trimethoprim sulfa, doxycycline, erythromycin, ceftiofur, enrofloxacin, oxytetracycline and metronidazole on the fecal microbiome in healthy horses (Costa et al., 2015; Arnold et al., 2020; Liepman, 2022). Regardless of mechanism of action, antibiotics typically reduce diversity (species richness and evenness) and alter the bacterial community structure of the fecal microbiome, even when animals maintain normal health status and fecal character (Arnold et al., 2021). These effects typically require at least 30 days before the microbiome returns to baseline (Gomez et al, 2023). In horses with colitis, changes in the microbiome are often significant. Horses with AAD demonstrate the most severe disruption of the fecal microbiome compared with horses with Salmonella or undifferentiated colitis. These changes are evident from the phylum to species level, and include important phyla such as Bacteroidetes, Firmicutes, Fibrobacter and Verrucomicrobia (Arnold et al., 2020; Liepman, 2022; Costa et al., 2015). Alterations in the microbiota result in functional metabolic changes that are clinically manifested by diarrhea. Potential changes include alterations in the metabolism of bile acids, carbohydrates including short chain fatty acids, amino acids, lipids and proteins. There is also evidence that antimicrobials increase intestinal permeability via effects on tight junction proteins and by compromising the barrier function provided by the mucus layer between the enterocytes and gut lumen. Recent work comparing horses on antimicrobials that did and did not develop diarrhea confirm that horses with diarrhea have depletion of Verrocomicrobia and metabolites related to gastrointestinal barrier function (Arnold et al., 2021).
148 The equine dermal microbiome: State of the science
Authors: Perry Erin B
Published: September 2024

Equine microbiome research has rapidly moved from a fledgling field to a thriving and productive area of research. Impacts to the equine gastrointestinal microbiome have been examined related to travel, antibiotic administration, meal size, fiber type, breed, sex and nutrient level. Although advances in this field are exciting, data related to the dermal microbiota are sorely lacking. Conducting equine microbiome research presents unique challenges and opportunities. Coordination for data collection in conjunction with other studies will be reviewed. Diet is widely recognized as a significant modulating factor to the microbiome and will be reviewed as a potential consideration in equine dermal microbiome research. This presentation will highlight the limited data available on equine dermal microbiota and identify potential areas for further examination. Studies reporting the characteristics of equine dermal measures will be discussed and gaps in current understanding will be identified. Specific conditions including equine pastern dermatitis as well as wound dressing methods will be examined, and a discussion of future works will be included. Dermatological studies of the microbiome in humans and canines will be examined as a potential map for the future of equine dermal microbiome research. As microbiome research continues to evolve, its impact on equine health has become increasingly apparent. The skin functions as a protective organ and is the first line of defense against pathogenic invasion and immune function support. It is home to bacteria, fungi and viruses with many roles similar to those of the gastrointestinal microbiome. This presentation will highlight the critical need for increased understanding of the dermal microbiome in conjunction with current equine gastrointestinal microbiome studies.
76 Camera vision grading and objective tenderness outcomes of steers fed lubabegron fumarate for the final 56 d of the feeding period
Authors: Wendler Wilsey M , Lawrence Ty , Davis Michael S , Rincker Phil J , Pyatt Nathan , Koers Wally
Published: September 2024

Limited research has compared no beta-agonist, ractopamine and lubabegron in feedlot cattle. We evaluated carcass quality and yield variables using a camera grading instrument and also examined objective tenderness outcomes. Treatments were negative control (no beta-ligand; CON), Optaflexx (ractopamine hydrochloride, 300 mg·steer-1·d-1 for 35 d; OPT), and Experior (lubabegron fumarate, 36 mg·steer-1·d-1 for 56 d + 4 d removal; 0EXP) fed for 198 d. Additional EXP treatments investigated total days on feed (DOF) of 184 d (-14EXP), 212 d (+14EXP) and 226 d (+28EXP). Carcasses (n = 2,517) were instrument graded 24 h post-mortem. Longissimus tenderness and lipid content were evaluated in a subset (n = 361) of carcasses via slice shear force and ether extract. Statistical analyses were conducted using mixed models; pen was the experimental unit, treatment was the fixed effect, block was a random effect, and means were separated with the Tukey-Kramer adjustment. Longissimus muscle area (LMA) was 4.0 to 6.2 cm2 larger (P < 0.01) for steers fed EXP compared with CON, which did not differ from OPT. Weight corrected LMA (LMA:HCW) was 1.3 cm2/100 kg larger (P < 0.01) for -14EXP compared with CON. Marbling score was 31 to 39 points lower (P < 0.01) for -14EXP compared with CON and OPT, whereas 0EXP, +14EXP and +28EXP were similar to CON and OPT. Total number of fat pieces within the longissimus did not differ (P = 0.11) across treatments, however number of fat pieces in the lateral one-half of the longissimus decreased (P ≤ 0.03) for -14EXP and +28EXP, whereas +14EXP tended (P = 0.09) to decrease compared with CON. Total meat area was 3.7 percentage points greater (P < 0.01) for -14EXP compared with CON; +14EXP and +28EXP tended (P = 0.07) to be greater than CON. Total fat area was 1.6 to 1.8 percentage points less (P ≤ 0.02) for 0EXP, +14EXP, and +28EXP when compared with CON. Compared with CON, dorsal-ventral longissimus distance increased (P < 0.01) by 3.3 to 5.4% for -14EXP, 0EXP, +14EXP and +28EXP. Medial-lateral longissimus distance increased 1.9 to 2.5 % (P < 0.01) for +14EXP and +28EXP compared with CON, whereas -14EXP tended (P = 0.08) to increase. Percentage intramuscular fat (IMF) was similar (P ≥ 0.44) for +14EXP, +28EXP, and OPT compared with CON, whereas 0EXP tended (P = 0.09) to be less. Marbling score and IMF were moderately correlated (r = 0.66). Slice shear force values were 20.1% greater (P < 0.02) for +14EXP compared with CON, whereas 0EXP tended (P = 0.09) to be greater and +28EXP, -14EXP and OPT were similar (P ≥ 0.28) to CON. These findings illustrate the effect of EXP on carcass traits and tenderness in feedlot cattle.
137 Possible mechanisms underlying enhanced intramuscular adipogenesis in Wagyu cattle
Authors: Du Min , Fu Xing
Published: September 2024

The quality of beef hinges significantly on the abundance of intramuscular fat and tenderness. Intramuscular fat accumulation results directly from intramuscular adipogenesis, while tenderness is adversely affected by collagenous intramuscular connective tissue. Both intramuscular fat and connective tissue originate from fibro/adipogenic progenitors (FAPs), a group of bipotent progenitors. Wagyu cattle are renowned for their tender beef with rich intramuscular fat, likely owing to the distinctive features of Wagyu FAPs. Our study has identified fewer myogenic cells but more FAPs with greater adipogenic potential in Wagyu compared with Angus muscle. Furthermore, single-cell transcriptomic analysis identified that Wagyu FAPs exhibit greater adipogenic and decreased fibrogenic characteristics compared with FAPs in Brahman cattle, which generally produce low-quality beef with limited intramuscular fat and tenderness. Interestingly, Wagyu muscle also contains more abundant vascular cells, crucial for supporting adipogenesis. Mechanistic studies have unveiled several signaling pathways, including the bone morphogenetic protein signaling and the alternative complement pathway of the complement system, which likely contributes to the heightened adipogenic programming of Wagyu FAPs and is subject to epigenetic regulation.
138 Regulation of post protein translational modification in adipogenesis and fat accumulation in pigs
Authors: Yin Jingdong
Published: September 2024

In this study, we explored the role of protein transcriptional modification (PTM) in the adipogenesis and fat accumulation of intramuscular adipocytes. Intramuscular fat (IMF) is mainly stored in adipocytes interspersed in the perimysial space or within fascicles, and its content is a key factor attributing to meat quality in farm animals, especially in terms of tenderness, flavor and juiciness. The early stage from the fetus to the neonate is crucial for skeletal muscle development involving myogenesis, adipogenesis, and fibrogenesis, and is susceptible to environmental factors. Previous studies have been subjected to explore the molecular mechanism involved in IMF development. However, it was obscured by muscular background of IMF adipocytes. Therefore, we investigated PTM dynamics from three aspects: 1) first analyzed PTM levels of lysine acetylation (Kac), 2-hydroxyisobutyrylation (Khib), crotonylation (Kcr) and succinylation (Ksu) in three distinct differentiation potenctial primary stem cells, including myogenic precursor cells (MPCs), fibro-adipogenic progenitors (FAPs) and MSCs isolated from neonatal longissimus dorsi muscle of pigs within 3-d of age; 2) Comparing the Khib levels of proliferative and differentiated FAPs; and 3) Exploring the role of Khib modification in the adipose tissue of obese- and lean-types of pigs. We found that only Khib level in FAPs was significantly greater than MSCs. During adipogenic differentiation of FAPs, the modification level of Khib was significantly increased quadratically in parallel with protein levels of acylation regulatory enzymes KAT5 (writer) and HDAC2 (Eraser). In comparison of Khib levels in FAPs in proliferation and in differentiation and Khib levels in backfat tissues from obese pigs (Laiwu pigs) and lean pigs (Duroc pigs), we also demonstrated that Khib modification level was positive correlated with adipogenic differentiation and fat accumulation. Accordingly, the expression patterns of KAT5 and HDAC2 were parallel to the degree of lipid accumulation in the backfat adipose tissue of finishing pigs. Furthermore, we showed that KAT5 knockdown in FAPs inhibited adipogenic differentiation, while HDAC2 knockdown enhanced adipogenic differentiation of FAPs. By employing C3H10T1/2 cells, we identified EON1 involved in Khib modification in regulation of adipo gesis and fat accumulation with analysis of Liquid chromatography-tandem mass spectrometry (LC-MS/MS) using the Tandem Mass Tag (TMT Through conditional loss- and gain-of-function mutations, we further demonstrated that khib modification of ENO1 is necessary for preadipocyte differentiation and subsequent fat accumulation by mediating cellular glycolysis. In conclusion, we are the first to reveal the role of Khib modification in adipogenesis and fat deposition in pigs, and provided new clues for the improvement of fat accumulation and distribution via genetic selection and nutritional strategy in pigs.
139 Metabolic regulation of intramuscular adipose tissue development
Authors: Smith Stephen B
Published: September 2024

Acetate arguably is the most important substrate for de novo fatty acid biosynthesis in bovine adipose tissue. However, including glucose in incubation media in vitro strongly stimulates fatty synthesis from acetate; additionally, glucose carbon is essential for triacylglycerol synthesis from acetate. Our laboratory is unique in that we utilize bovine intramuscular (i.m.) and subcutaneous (s.c.) adipose tissue explants dissected from beef longissimus muscle immediately post-exsanguination to study bovine adipose tissue metabolism. Four decades ago, using this experimental technique, we established that glucose is a primary substrate for fatty acid biosynthesis in i.m. adipose tissue. Recent research in our laboratory has addressed the hypothesis that acetate and/or long-chain fatty acids (LCFA) differentially affect lipid filling of i.m. and s.c. adipose tissue. We had previously demonstrated that, whereas s.c. adipose tissue is highly responsive to isoproterenol (a non-selective ß-adrenergic agonist), i.m. adipose tissue is relatively refractory to isoproterenol. This subsequently was confirmed in our laboratory utilizing primary cultures of bovine s.c. and i.m. adipocytes. We currently are focusing on the G-coupled protein receptors-43 (GPR43) and GPR120. Several previous studies from our laboratory have documented GPR43 expression in i.m. and s.c. adipose tissue, and we more recently demonstrated GPR120 expression in bovine adipose tissues. Acetate is a ligand for GPR43, whereas LCFA are ligands for GPR120. The binding of ß-adrenergic agonists to ß-adrenergic receptors increases the production of cyclic adenosine monophosphate (cAMP), whereas binding of acetate and LCFA to GPR43 and GPR120, respectively, decreases cAMP production. Thus, binding of circulating acetate and LCFA to their respective GPR receptors putatively should lead to increase lipid filling of bovine adipose tissues. A current study from our laboratory demonstrated that acetate had no effect on forskolin-stimulated cAMP production in i.m. or s.c. adipose tissue explants unless the culture medium also included oleic acid (18:1n-9). A subsequent study confirmed that oleic acid and palmitic acid (16:0), but not acetate, strongly depressed forskolin-stimulated cAMP production in s.c. adipose tissue explants; oleic and palmitic acid were much less effective in depressing cAMP production in i.m. adipose tissue explants. Unusually, GPR43 expression was detected in neither s.c. adipose tissue nor i.m. adipose tissue in our most recent study, whereas GPR120 expression was readily detected in both adipose tissue types. We conclude the following from these recent studies: LCFA binding to GPR120 is more effective than acetate binding to GPR43 in promoting lipid filling in bovine adipose tissue; and LCFA binding to GPR120 putatively would promote greater lipid filling in s.c. adipose tissue than in i.m. adipose tissue.