Total-Body Irradiation Alters White Matter Volume and Microstructural Integrity in Rhesus Macaques

PURPOSE

Long-term survivors of brain irradiation can experience irreversible injury and cognitive impairment. T1-weighted and diffusion tensor magnetic resonance imaging (MRI) are used to evaluate brain volume and white matter (WM) microstructure in neurodevelopmental and neurodegenerative conditions. The goal of this study was to evaluate the long-term effects of single-dose total-body irradiation (TBI) or TBI with 5% partial-body sparing on brain volumetrics and WM integrity in macaques.

METHODS AND MATERIALS

We used MRI scans from a cohort of male rhesus macaques (age range, 3.6-22.8 years) to compare global and regional brain volumes and WM diffusion in survivors of TBI (T1-weighted, n = 137; diffusion tensor imaging, n = 121; dose range, 3.5-10 Gy) with unirradiated controls (T1-weighted, n = 48; diffusion tensor imaging, n = 38).

RESULTS

In all regions of interest, radiation affected age-related changes in fractional anisotropy, which tended to increase across age in both groups but to a lesser extent in the irradiated group (interaction P < .01). Depending on the region of interest, mean diffusivity decreased or remained the same across age in unirradiated animals, whereas it increased or did not change in irradiated animals. The increases in mean diffusivity were driven by changes in radial diffusivity, which followed similar trends across age. Axial diffusivity did not differ by irradiation status. Age-related changes in relative volumes in controls reflected normal trends in humans, with increasing WM and decreasing gray matter until middle age. Cerebrospinal fluid (CSF) volume did not differ across age in controls. WM volume was lower and CSF volume was higher in young irradiated macaques. WM volume was similar between groups, and CSF volume lower in older irradiated macaques. Gray matter volume was unaffected by radiation.

CONCLUSIONS

TBI results in delayed WM expansion and long-term disruption of WM integrity. Diffusion changes suggest that myelin injury in WM is a hallmark of late-delayed radiation-induced brain injury.

Epigenetic MLH1 silencing concurs with mismatch repair deficiency in sporadic, naturally occurring colorectal cancer in rhesus macaques

BACKGROUND

Naturally occurring colorectal cancers (CRC) in rhesus macaques share many features with their human counterparts and are useful models for cancer immunotherapy; but mechanistic data are lacking regarding the comparative molecular pathogenesis of these cancers.

METHODS

We conducted state-of-the-art imaging including CT and PET, clinical assessments, and pathological review of 24 rhesus macaques with naturally occurring CRC. Additionally, we molecularly characterized these tumors utilizing immunohistochemistry (IHC), microsatellite instability assays, DNAseq, transcriptomics, and developed a DNA methylation-specific qPCR assay for MLH1, CACNA1G, CDKN2A, CRABP1, and NEUROG1, human markers for CpG island methylator phenotype (CIMP). We furthermore employed Monte-Carlo simulations to in-silico model alterations in DNA topology in transcription-factor binding site-rich promoter regions upon experimentally demonstrated DNA methylation.

RESULTS

Similar cancer histology, progression patterns, and co-morbidities could be observed in rhesus as reported for human CRC patients. IHC identified loss of MLH1 and PMS2 in all cases, with functional microsatellite instability. DNA sequencing revealed the close genetic relatedness to human CRCs, including a similar mutational signature, chromosomal instability, and functionally-relevant mutations affecting KRAS (G12D), TP53 (R175H, R273*), APC, AMER1, ALK, and ARID1A. Interestingly, MLH1 mutations were rarely identified on a somatic or germline level. Transcriptomics not only corroborated the similarities of rhesus and human CRCs, but also demonstrated the significant downregulation of MLH1 but not MSH2, MSH6, or PMS2 in rhesus CRCs. Methylation-specific qPCR suggested CIMP-positivity in 9/16 rhesus CRCs, but all 16/16 exhibited significant MLH1 promoter hypermethylation. DNA hypermethylation was modelled to affect DNA topology, particularly propeller twist and roll profiles. Modelling the DNA topology of a transcription factor binding motif (TFAP2A) in the MLH1 promoter that overlapped with a methylation-specific probe, we observed significant differences in DNA topology upon experimentally shown DNA methylation. This suggests a role of transcription factor binding interference in epigenetic silencing of MLH1 in rhesus CRCs.

CONCLUSIONS

These data indicate that epigenetic silencing suppresses MLH1 transcription, induces the loss of MLH1 protein, abrogates mismatch repair, and drives genomic instability in naturally occurring CRC in rhesus macaques. We consider this spontaneous, uninduced CRC in immunocompetent, treatment-naïve rhesus macaques to be a uniquely informative model for human CRC.

Assessing cerebrovascular reactivity (CVR) in rhesus macaques (Macaca mulatta) using a hypercapnic challenge and pseudo-continuous arterial spin labeling (pCASL)

Cerebrovascular reactivity (CVR) is a measure of cerebral small vessels' ability to respond to changes in metabolic demand and can be quantified using magnetic resonance imaging (MRI) coupled with a vasoactive stimulus. Reduced CVR occurs with neurodegeneration and is associated with cognitive decline. While commonly measured in humans, few studies have evaluated CVR in animal models. Herein, we describe methods to induce hypercapnia in rhesus macaques (Macaca mulatta) under gas anesthesia to measure cerebral blood flow (CBF) and CVR using pseudo-continuous arterial spin labeling (pCASL). Fifteen (13 M, 2 F) adult rhesus macaques underwent pCASL imaging that included a baseline segment (100% O2) followed by a hypercapnic challenge (isoflurane anesthesia with 5% CO2, 95% O2 mixed gas). Relative hypercapnia was defined as an end-tidal CO2 (ETCO2) ≥5 mmHg above baseline ETCO2. The mean ETCO2 during the baseline segment of the pCASL sequence was 34 mmHg (range: 23-48 mmHg). During this segment, mean whole-brain CBF was 51.48 ml/100g/min (range: 21.47-77.23 ml/100g/min). Significant increases (p<0.0001) in ETCO2 were seen upon inspiration of the mixed gas (5% CO2, 95% O2). The mean increase in ETCO2 was 8.5 mmHg and corresponded with a mean increase in CBF of 37.1% (p<0.0001). The mean CVR measured was 4.3%/mmHg. No anesthetic complications occurred as a result of the CO2 challenge. Our methods were effective at inducing a state of relative hypercapnia that corresponds with a detectable increase in whole brain CBF using pCASL MRI. Using these methods, a CO2 challenge can be performed in conjunction with pCASL imaging to evaluate CBF and CVR in rhesus macaques. The measured CVR in rhesus macaques is comparable to human CVR highlighting the translational utility of rhesus macaques in neuroscience research. These methods present a feasible means to measure CVR in comparative models of neurodegeneration and cerebrovascular dysfunction.

The effect of different implant programs on beef × dairy steer feedlot growth performance and carcass characteristics

The objective of this study was to evaluate potency and timing of trenbolone acetate (TBA) administration on live performance and carcass characteristics of beef × dairy steers. A total of 6,895 beef × dairy steers [initial body weight (BW) = 157 ± 5.2 kg] were allotted into 30 pens, with pen as the experimental unit. Each pen was randomly assigned one of three implant treatments: 1) Revalor-IS (IS) at d 0, IS at d 80, and Revalor-XS (XS) at d 160 (IS/IS/XS); 2) Ralgro at d 0, IS at d 80, and XS at d 160 (Ral/IS/XS); or 3) Encore at d 0 and XS at d 160 (Enc/XS). Steers were blocked by arrival date, each pen was terminally sorted in three ways at 257 ± 22 days on feed and harvested at 329 ± 25 days on feed. For live and carcass outcomes, fixed effect of implant treatment and random effect of block was evaluated. Data are reported on a deads and removals out basis. Removals, morbidity, and mortality were similar (P ≥ 0.45). Steers administered TBA prior to d 160 were 5.8 kg heavier (P = 0.03) than Enc/XS steers at d 160. Final BW was not different (P = 0.78). Early administration of a TBA-containing implant resulted in an increased prevalence of bullers [2.40%, 5.18%, 6.86% (for Enc/XS, Ral/IS/XS, and IS/IS/XS) respectively; P < 0.01]. Dry matter intake (DMI) was 2.3% greater (P < 0.01) in steers administered Enc/XS compared to IS/IS/XS; however, DMI as a percentage of BW, average daily gain, and feed efficiency were not different (P ≥ 0.12). Dressing percentage, hot carcass weight, heavy carcass occurrence, Longissimus muscle area, and 12th rib fat thickness were similar among all steers (P ≥ 0.28). Marbling score tended to be greatest for Enc/XS and Ral/IS/XS (P = 0.09). Enc/XS graded a greater proportion of USDA Prime and fewer USDA Select carcasses than IS/IS/XS (P < 0.05). Enc/XS and Ral/IS/XS tended (P = 0.09) to have more USDA Yield Grade (YG) 1 carcasses. While delayed administration or decreased total potency of TBA-containing implants may decrease buller incidence and improve Quality Grade, few differences were observed in live or carcass outcomes.

Abstract 5203: Naturally occurring colorectal cancer in rhesus macaques as model for human cancer immunotherapy: a first report on pembrolizumab ± radiotherapy

Introduction: Rhesus macaques share extensive similarities with humans including immune cell populations, regulatory mechanisms, and targets for cancer immunotherapy but also naturally develop cancers at similar life stages. Hence, treating rhesus macaques with spontaneous tumors bears enormous potential as model for human cancer immunotherapy.

Material and Methods: We identified 2 female rhesus macaques, 23.6y (CRC_1) and 20.3y (CRC_2) old with naturally occurring colorectal cancer by imaging and clinical assessments. We collected a pre-treatment tumor biopsy in CRC_1 prior to treatment with 8 Gy intensity-modulated radiotherapy (IMRT) to the proximal portion of the tumor and 2 mg/kg i.v. pembrolizumab. The second candidate (CRC_2) was not tumor biopsy-eligible due to anemia and was treated with pembrolizumab alone. We collected blood and peripheral lymph nodes (LNs) pre- and on-treatment and complete tissue collection was performed at the 3w time point including tumor-adjacent mesenteric LNs. Follow-up assessments include IHC (e.g. CD3, CD20, IBA1), flow cytometry, cytokine assessment in plasma, and transcriptomics of LN and tumor samples.

Results and Discussions: Imaging revealed focal thickening of the proximal colonic wall with disrupted architecture in CRC_1 and focal colonic thickening and an enlarged adjacent LN in CRC_2. Both tumors displayed mismatch repair-deficiency (MLH1 & PMS2 loss) and a drastic reduction in infiltrating CD3 cells in neoplastic areas compared to adjacent healthy colon. On treatment, tumor-associated LNs demonstrated a mild increase in CD20+ cells in the medullary sinuses of both patients and increased follicle numbers with normal follicular architecture in reference to peripheral LNs. In both patients there was an increased number of tertiary lymphoid structures (TLS) surrounding the tumors, predominately populated with CD20+ cells and with Ki67+ germinal centers, profoundly so in CRC_2. Moreover, IBA1+ cells abundantly infiltrated both tumors but showed a higher aggregation within the stromal elements of the neoplasms. A gradient of histologic differentiation was evident in CRC_1 and coincided with a reduction of TLS, IBA1+ cell abundance, and CD3+ cell infiltration in those areas which were poorly differentiated. Within the irradiated tumor of CRC_1, there were abundant apoptotic cells which stained positively with cleaved caspase 3 at the 3w time point. Circulating blood counts as preliminary peripheral read-out revealed a reduction in circulating lymphocytes in both patients beginning at 3d (CRC_1) resp. 6d (CRC_2) and a sharp increase in monocytes at 3d in unirradiated patient CRC_2.

Conclusion: The immunological and tumoral response to pembrolizumab and radiotherapy matches the clinical response in humans and enables an unprecedented examination of the peripheral and local lymph node response.

Citation Format: Simon Deycmar, George W. Schaaf, Brendan J. Johnson, J. Daniel Bourland, James D. Ververs, Christopher T. Whitlow, J. Mark Cline. Naturally occurring colorectal cancer in rhesus macaques as model for human cancer immunotherapy: a first report on pembrolizumab ± radiotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5203.

Pharmacokinetics and safety of TCMCB07, a melanocortin-4 antagonist peptide in dogs

The melanocortin-4 receptor (MC4R) antagonistic peptide TCMCB07 was developed for the treatment of cachexia. The objectives of this study were to examine pharmacokinetics and safety of TCMCB07 administered subcutaneously to healthy dogs. Dogs were treated with high- (2.25 mg kg-1 ) (n = 5) and low-dose TCMCB07 (0.75 mg kg-1 ) (n = 5) once daily for 28 days with a 14-day washout period between groups. Histamine levels, complete blood count, chemistry panel, blood pressure, 24-hour Holter recording, and pharmacokinetic parameters were monitored in the high-dose group. Physical examination changes were limited to weight gain and darkening of the coat color. There was no elevation of plasma histamine within 24 hours of injection but there was a significant elevation of plasma histamine across time. An approximately doubled eosinophil count and an approximately 25% increase, and then 25% decrease back to pre-treatment plasma phosphorous were also found, although both remained within the reference interval. Serial blood pressure and 24-hour Holter monitors revealed no clinically relevant changes. A difference was found in the AUC between dosing groups and a significant effect of dose, time, and interaction was noted for Vd . Low-dose TCMCB07 had a Cmax of 2.1 ug ml-1 at day 28, compared to high-dose TCMCB07 which had a Cmax 3.6 ug ml-1 at day 28. Once-daily subcutaneous administration of TCMCB07 was well-tolerated for up to 28 days in dogs when administered at doses one and three times (0.75 mg kg-1 and 2.25 mg kg-1 ) the predicted therapeutic dose and pharmacokinetic parameters are described. SIGNIFICANCE STATEMENT: Melanocortin-4 receptor (MC4R) antagonistic peptide TCMCB07 is safe at both low and high doses in dogs. Therapy was tolerated well as determined by physical examination, clinical pathology, and cardiovascular parameters; darkening of the coat was noted with treatment and resolved with discontinuation. Pharmacokinetics are described and further study in the naturally occurring canine model is warranted.

How to reduce parental provision of unhealthy foods to 3- to 8-year-old children in the home environment? A systematic review utilizing the Behaviour Change Wheel framework

BACKGROUND AND OBJECTIVE

The effectiveness of obesity prevention interventions to improve children's diet can be enhanced. Deconstructing past interventions can identify components with potential to change behaviour. This systematic review using the Behaviour Change Wheel aimed to examine the behaviour change content of interventions supporting parents of 3- to 8-year olds to reduce provision of unhealthy foods to children.

METHODS

Ebscohost, Ovid, Scopus and Web of Science were searched. Eligible studies included controlled interventions with active parent involvement, at least one intervention strategy and outcome measure for unhealthy foods ≥3 months from baseline. Seventeen interventions were included describing 18 intervention arms.

RESULTS

Interventions frequently targeted parents' reflective motivation (n = 17) and psychological capability (n = 15), through education (n = 15) or enablement (n = 15) intervention functions and service provision (n = 18) policy category. Only 24 of the 93 behaviour change techniques were used with an average of five techniques used per intervention.

CONCLUSIONS

Existing interventions achieving small reductions in unhealthy food intake are homogenous in approach. There is potential to utilize untapped behaviour change techniques, through comprehensive intervention design and behavioural analysis guided by the Behaviour Change Wheel. Interventions targeting opportunity through persuasion, modelling or environmental restructuring, and using different policy categories are urgently needed to provide an evidence base to inform policy and practice.

Cortical Thinning and Structural Bone Changes in Non-Human Primates after Single-Fraction Whole-Chest Irradiation

Stereotactic body radiation therapy (SBRT) is associated with an increased risk of vertebral compression fracture. While bone is typically considered radiation resistant, fractures frequently occur within the first year of SBRT. The goal of this work was to determine if rapid deterioration of bone occurs in vertebrae after irradiation. Sixteen male rhesus macaque non-human primates (NHPs) were analyzed after whole-chest irradiation to a midplane dose of 10 Gy. Ages at the time of exposure varied from 45-134 months. Computed tomography (CT) scans were taken 2 months prior to irradiation and 2, 4, 6 and 8 months postirradiation for all animals. Bone mineral density (BMD) and cortical thickness were calculated longitudinally for thoracic (T) 9, lumbar (L) 2 and L4 vertebral bodies; gross morphology and histopathology were assessed per vertebra. Greater mortality (related to pulmonary toxicity) was noted in NHPs <50 months at time of exposure versus NHPs >50 months ( P = 0.03). Animals older than 50 months at time of exposure lost cortical thickness in T9 by 2 months postirradiation ( P = 0.0009), which persisted to 8 months. In contrast, no loss of cortical thickness was observed in vertebrae out-of-field (L2 and L4). Loss of BMD was observed by 4 months postirradiation for T9, and 6 months postirradiation for L2 and L4 ( P < 0.01). For NHPs younger than 50 months at time of exposure, both cortical thickness and BMD decreased in T9, L2 and L4 by 2 months postirradiation ( P < 0.05). Regions that exhibited the greatest degree of cortical thinning as determined from CT scans also exhibited increased porosity histologically. Rapid loss of cortical thickness was observed after high-dose chest irradiation in NHPs. Younger age at time of exposure was associated with increased pneumonitis-related mortality, as well as greater loss of both BMD and cortical thickness at both in- and out-of-field vertebrae. Older NHPs exhibited rapid loss of BMD and cortical thickness from in-field vertebrae, but only loss of BMD in out-of-field vertebrae. Bone is sensitive to high-dose radiation, and rapid loss of bone structure and density increases the risk of fractures.

Effects of tannic acid on growth performance, carcass characteristics, digestibility, nitrogen volatilization, and meat lipid oxidation of steers fed steam-flaked corn-based finishing diets

Effects of a tannic acid blend (ByPro; Silvateam USA, Ontario, CA) added to steam-flaked corn-based fishing diets on beef cattle growth performance, carcass characteristics, nutrient digestibility, fecal N volatilization, and meat lipid oxidation were evaluated. Steers ( = 144; 349 ± 25 kg initial BW) were blocked by initial BW and assigned randomly to 1 of 3 treatments with 12 pens/treatment and 4 steers/pen and fed ad libitum. Treatments included a control (CON; no ByPro) and ByPro fed at 30 or 60 g DM/steer daily (30-ByPro and 60-ByPro, respectively). Pen fecal samples were collected 7 d after cattle were shipped to slaughter for estimation of N volatilization. Strip loins were aged for 21 d for evaluation of color and antioxidant activity. Intake quadratically increased ( = 0.05) from d 0 to 35, whereas linear trends were observed for increased DMI from d 0 to 105 and d 0 to slaughter ( = 0.07 and = 0.06, respectively), resulting in a 3.7% greater overall DMI for 60-ByPro than for CON. No differences were detected for carcass-adjusted ADG ( = 0.65) or G:F ( = 0.17). Carcass characteristics including HCW ( = 0.52), fat thickness ( = 0.32), LM area ( = 0.57), quality grade ( = 0.44), yield grade ( = 0.29), and percentage of condemned livers ( = 0.13) were not affected by treatments. Apparent total tract digestibility of starch linearly decreased tendency ( = 0.03) with increasing ByPro dose, whereas tends for a linear decrease ( = 0.09) in CP and a quadratic increase ( = 0.09) in OM digestibility were observed. No effects of treatment ( ≥ 0.39) were noted for fecal N volatilization. An increase ( < 0.01) in metmyoglobin in strip loin steaks was observed with ByPro inclusion. Oxymyoglobin decreased ( < 0.01) as display day progressed, except on d 5, at which time CON and 30-ByPro steaks had lower proportions than 60-ByPro steaks. Only subtle changes in discoloration ratio and deoxymyoglobin were observed, whereas no effects ( ≥ 0.43) for pH or thiobarbituric acid reactive substances were noted. Feeding ByPro increased DMI during the first half of the feeding period without negatively affecting gain efficiency; however, fecal N retention was not altered by ByPro. ByPro did not negatively affect meat quality or carcass characteristics, and it did not seem to affect retail meat antioxidant activity.

Ionophore strategy affects growth performance and carcass characteristics in feedlot steers

One hundred ninety-two steers (BW = 354 ± 23.5 kg) were used in a randomized block design to evaluate the effects of ionophore and ractopamine hydrochloride (RH) supplementation strategies on performance and carcass characteristics. Twelve pens of 4 steers were assigned to each of the following treatments: unsupplemented control (CON), laidlomycin propionate (12.1 mg/kg DM) with or without RH (LPRH and LP, respectively), and monensin sodium (36.4 mg/kg DM) with RH (MSRH). Steers were fed for 151 d, of which respective treatments received RH (Actogain; Zoetis, Florham Park, NJ) at a rate of 300 mg/(animal · d) for the final 32 d. Laidlomycin was removed from the LPRH treatment during this period, as no combination feeding has been approved. Upon harvest, carcass data were collected by trained personnel, and subsequent analysis of the LM was conducted to estimate tenderness using Warner-Bratzler shear force (WBSF). Prior to RH supplementation, both LP and LPRH had greater ADG ( ≤ 0.02) and G:F ( < 0.01) than CON, whereas MSRH was intermediate. During the final 32 d, MSRH improved G:F ( ≤ 0.02) compared to all other treatments and tended to increase ADG over unsupplemented controls ( = 0.05). Cattle receiving LP without RH had significantly greater BW at d 151 than CON ( = 0.02), whereas both RH treatments tended to improve final BW ( ≤ 0.09). Ionophores improved ADG ( ≤ 0.03) and G:F ( < 0.01) for the entire feeding period, and although LP-supplemented cattle had greater DMI for the final 32 d than both RH treatments ( ≤ 0.01), intakes for the 151-d trial were similar among treatments. Carcass weights were greater ( = 0.04) in cattle fed LP with no RH than CON, where cattle yielded an average of 12 kg more HCW. Ractopamine increased LM area in MSRH-supplemented cattle ( = 0.03) and tended to increase LM area for steers receiving LPRH ( = 0.07). Longissimus steaks of MSRH-supplemented cattle had greater WBSF values than CON ( = 0.04) after 7 d of postmortem aging and greater WBSF values than LPRH steaks after 28 d ( = 0.03). All other carcass and WBSF measurements were similar among treatments. The results of this study indicate that LP supplementation without RH may yield a performance similar to and carcass responses associated with the administration of a β-agonist. These results also suggest that performance and carcass characteristics for cattle fed LP are similar to those of cattle fed monensin throughout the feeding period.

Anabolic payout of terminal implant alters adipogenic gene expression of the longissimus muscle in beef steers

This experiment evaluated the dose and payout pattern of trenbolone acetate (TBA) and estradiol-17β (E) on LM mRNA expression of adenosine monophosphate-activated protein kinase-ɑ (-ɑ), β, G protein-coupled receptor 41(), G protein-coupled receptor 43 (), γ, and stearoyl CoA desaturase () in finishing feedlot steers as indicators of adipogenesis and marbling development. British × Continental steers (n = 168; 14 pens/treatment; initial BW = 362 kg) were used in a randomized complete block design. Treatments included: no implant (NI), Revalor-S (REV-S; 120 mg TBA + 24 mg E), or Revalor-XS (REV-X; delayed release implant: 80 mg TBA + 16 mg E [uncoated], 120 mg TBA + 24 mg E [coated], 200 mg TBA + 40 mg E [total]). Steers were fed 1 time daily for an average of 164 d. The LM biopsies were collected (1 steer/pen) on d -1, 27, 55, and 111 relative to timing of implant. Total RNA was isolated from each sample and real-time quantitative PCR was used to measure quantity of -ɑ, β, , ,it, γ, and mRNA. No implant × day interactions were detected ( ≥ 0.19) in this experiment. Day impacted the mRNA expression of all adipogenic genes ( ≤ 0.02). The main effect of implant tended ( = 0.09) to influence expression of -ɑ, REV-X had an 8.8% increase over NI and an 18.7% increase over REV-S. Implant influenced ( = 0.03) mRNA expression of , expression of for the REV-X treatment was not different ( > 0.10) from NI, and both were greater ( ≤ 0.05) than REV-S (1.13, 1.00, and 0.67 ± 0.224 arbitrary units) for REV-X, NI, and REV-S, respectively. Implant also influenced ( = 0.02) expression of , expression of for REV-X was not different ( > 0.10) from NI, and both were greater ( ≤ 0.05) than REV-S (1.27, 1.07, and 0.72 ± 0.234 arbitrary units) for REV-X, NI, and REV-S, respectively. Implant influenced ( = 0.02) mRNA expression of γ in LM tissue, expression of γ for REV-X was not different ( > 0.10) from NI, and both were greater ( ≤ 0.05) than REV-S (1.09, 1.02, and 0.69 ± 0.195 arbitrary units) for REV-X, NI, and REV-S, respectively. The REV-X steers received the greatest anabolic dose of TBA + E without detriment to marbling scores. The increased mRNA expression of adipogenic genes for REV-X steers suggest that the delayed and gradual release of anabolic stimulants associated with REV-X might have mitigated decreases in marbling generally attributed to multiple combined TBA + E implants.

Viral Antigen Distribution in the Respiratory Tract of Cattle Persistently Infected with Bovine Viral Diarrhea Virus Subtype 2a

Tissues were obtained at necropsy from the nasal vestibule, turbinates, nasopharynx, trachea, tracheobronchial bifurcation, and lung from each of 10 clinically healthy calves persistently infected (PI) with bovine viral diarrhea virus (BVDV) serotype 2a. Tissues from the nasal vestibule were obtained by biopsy from five additional PI calves. Formalin-fixed tissues were processed for immunohistochemistry to localize the distribution of BVDV throughout the respiratory tract. Antigen distribution and intensity were subjectively evaluated. Throughout the respiratory tract, mononuclear leukocytes, vascular smooth muscle, and endoneural and perineural cells had BVDV immunoreactivity (BVDV-IR). Multifocally, squamous and ciliated columnar epithelium throughout the respiratory tract contained weak to moderate BVDV antigen. Viral antigen was not seen in goblet cells. BVDV-IR in mixed tubuloalveolar glands of the nasal cavity was weak to strong in serous secretory cells and ductular epithelium. Chondrocytes of the concha often contained BVDV antigen diffusely. Nasal mucus-secreting and tracheobronchial glands multifocally contained weak viral signal. In all cases, alveolar macrophages had moderate to strong BVDV-IR, whereas BVDV-IR in alveolar epithelial cells was weak to moderate. BVDV was present in interalveolar leukocytes and mesenchymal cells. Results indicate that serous secretions of the nasal cavity, productive viral infection of epithelium, and infected leukocytes in respiratory secretions are likely major sources of infectious BVDV from PI calves. The presence of BVDV antigen in respiratory epithelium is, at least, indirect support for the notion that this virus predisposes PI cattle to secondary microbial infections.

Zinc Methionine Supplementation Impacts Gene and Protein Expression in Calf-Fed Holstein Steers with Minimal Impact on Feedlot Performance

Providing cattle a more bioavailable zinc (Zn) source prior to administering a beta adrenergic agonist (βAA) may enhance the metabolic pool of primary nutrients that will influence the magnitude of the βAA response. Calf-fed Holstein steers were supplemented with a Zn methionine supplement (ZnMet; ZINPRO(®); Zinpro Corporation, Eden Prairie, MN) for 115 ± 5 days prior to harvest along with zilpaterol hydrochloride (ZH; Zilmax(®); Merck Animal Health, Summit, NJ) for the last 20 days with a 3-day withdrawal to evaluate the effects on growth and carcass performance together with gene and protein expression of skeletal muscle, adipose tissue, and fatty acid composition of polar and neutral lipid depots. Steers (n = 1296; initial weight = 468.5 ± 0.5 kg) were sorted by weight, blocked by harvest date, and randomly assigned to pens (n = 12) and treatments: control (90 ppm Zn from ZnSO4) and ZnMet (Control plus 720 mg Zn from ZnMet/hd/d). There were no differences (P > 0.05) in growth performance or carcass characteristics. The ZnMet-fed cattle had reduced (P < 0.05) abundance of myosin heavy chain (MHC)-IIX, β1-adrenergic receptor (βAR), peroxisome proliferator-activated receptor gamma, and stearoyl-CoA desaturase mRNA in skeletal muscle tissue. The ZnMet cattle had greater (P < 0.05) abundance of MHC-II protein, increased MHC-IIA and IIX cross-sectional areas (P < 0.05), an increased percentage of MHC-I fibers (P < 0.05), and a decreased percentage of MHC-IIX fibers (P < 0.05). The combination of ZnMet and ZH had positive biological effects on musculoskeletal tissue; however, these molecular effects were not significant enough to impact overall feedlot and carcass performance.

Effects of supplemental lysine and methionine with zilpaterol hydrochloride on feedlot performance, carcass merit, and skeletal muscle fiber characteristics in finishing feedlot cattle

Feeding zilpaterol hydrochloride (ZH) with ruminally protected AA was evaluated in a small-pen feeding trial. Crossbred steers ( = 180; initial BW = 366 kg) were blocked by weight and then randomly assigned to treatments (45 pens; 9 pens/treatment). Treatment groups consisted of no ZH and no AA (Cont-), ZH and no AA (Cont+), ZH and a ruminally protected lysine supplement (Lys), ZH and a ruminally protected methionine supplement (Met), and ZH and ruminally protected lysine and methionine (Lys+Met). Zilpaterol hydrochloride (8.3 mg/kg DM) was fed for the last 20 d of the finishing period with a 3-d withdrawal period. Lysine and Met were top dressed daily for the 134-d feeding trial to provide 12 or 4 g·hd·d, respectively, to the small intestine. Carcass characteristics, striploins, and prerigor muscle samples were collected following harvest at a commercial facility. Steaks from each steer were aged for 7, 14, 21, and 28 d, and Warner-Bratzler shear force (WBSF) was determined as an indicator of tenderness. Prerigor muscle samples were used for immunohistological analysis. Cattle treated with Met and Lys+Met had increased final BW ( < 0.3) and ADG ( < 0.05) compared to Cont- and Cont+. Supplementation of Lys, Met, and Lys+Met improved G:F ( < 0.05) compared to Cont- during the ZH feeding period (d 111 to 134) as well as the entire feeding period ( < 0.05). Zilpaterol hydrochloride increased carcass ADG ( < 0.05) when compared to non-ZH-fed steers. Methionine and Lys+Met treatments had heavier HCW ( < 0.02) than that of Cont-. Yield grade was decreased ( < 0.04) for Cont+ steers compared to steers treated with Lys, Lys+Met, and Cont-. Tenderness was reduced ( < 0.05) with ZH regardless of AA supplementation. Lysine, Met, Lys+Met, and Cont+ had less tender steaks ( < 0.05) throughout all aging groups compared to Cont-. Steaks from Lys-treated steers were less tender ( < 0.05) than those of Cont+ during the 7- and 14-d aging periods. Nuclei density was the greatest with Cont- cattle compared to all other treatments suggesting a dilution effect of the nuclei in the larger muscle fibers with ZH feeding. Supplementation of Met in conjunction with ZH feeding increased ADG and HCW although this may lead to decreased tenderness even after aging for 28 d. These findings indicated that steers fed ZH may require additional AA absorbed from the small intestine to maximize performance.

Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations before and after an endotoxin challenge

English × Continental heifers ( = 180) were sourced in 2 loads (219.3 ± 16.0 and 221.4 ± 16.4 kg, respectively) from commercial auction barns to study the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly received heifers. A completely randomized block design was used with BW nested within arrival load and blocked by BW into 3 dietary treatments (36 pens, 5 heifers/pen, 12 blocks, 3 pens/block, and 12 pens/treatment). Treatment diets contained 1) 0% DCP (control diet [CON]), 2) 10% DCP, or 3) 20% DCP on a DM basis. Diets containing DCP were exchanged with steam-flaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from d 0 to 28, d 28 to 42, and d 42 to 56, respectively. Over the 56-d trial period, as the amount of dietary DCP increased, DMI decreased ( = 0.01), ADG decreased ( < 0.01), and G:F decreased ( = 0.02). From d 0 to 28, there was no difference in the observed minus the predicted NEg of the diet ( = 0.73); from d 28 to 42, there was a linear increase in NEg favoring DCP treatments ( < 0.01); and from d 42 to 56, there was a linear decrease in NEg against the DCP treatments ( < 0.01). At the conclusion of the trial, a subset of heifers ( = 22; 307.89 ± 3.32 kg on d 63) were used to evaluate blood metabolite concentrations before and after a lipopolysaccharide (LPS) challenge. On d 63, heifers were fitted with jugular catheters and moved into individual stalls. On d 64, heifers were intravenously challenged with LPS (0.5 μg/kg BW), and blood samples were collected every 0.5 h from -2 to 8 h and at 24 h relative to the LPS challenge (0 h). Serum glucose, serum urea nitrogen (SUN), and NEFA concentrations were determined. Cattle lost less weight at both 24 and 72 h after the LPS challenge with increasing DCP percentage ( < 0.01). Glucose ( = 0.12) and NEFA ( = 0.13) concentrations did not differ before the LPS challenge; however, there was a treatment effect for SUN, with elevated concentrations of SUN in CON cattle ( < 0.01). After the LPS challenge, DCP-fed cattle had reduced glucose, elevated NEFA, and reduced SUN concentrations ( ≤ 0.01). Results indicate that dietary DCP modulated metabolite concentrations in heifers following an endotoxin challenge and affected feedlot performance when incorporated in receiving diets in replacement of corn. Future studies will need to address strategies to increase DMI or explore levels of DCP less than 10% in the diet of newly received heifer calves.

AMPKα, C/EBPβ, CPT1β, GPR43, PPARγ, and SCD Gene Expression in Single- and Co-cultured Bovine Satellite Cells and Intramuscular Preadipocytes Treated with Palmitic, Stearic, Oleic, and Linoleic Acid

We previously demonstrated that bovine subcutaneous preadipocytes promote adipogenic gene expression in muscle satellite cells in a co-culture system. Herein we hypothesize that saturated fatty acids would promote adipogenic/lipogenic gene expression, whereas mono- and polyunsaturated fatty acids would have the opposite effect. Bovine semimembranosus satellite cells (BSC) and intramuscular preadipocytes (IPA) were isolated from crossbred steers and cultured with 10% fetal bovine serum (FBS)/Dulbecco’s Modified Eagle Medium (DMEM) and 1% antibiotics during the 3-d proliferation period. After proliferation, cells were treated for 3 d with 3% horse serum/DMEM (BSC) or 5% FBS/DMEM (IPA) with antibiotics. Media also contained 10 μg/mL insulin and 10 μg/mL pioglitazone. Subsequently, differentiating BSC and IPA were cultured in their respective media with 40 μM palmitic, stearic, oleic, or linoleic acid for 4 d. Finally, BSC and IPA were single- or co-cultured for an additional 2 h. All fatty acid treatments increased (p = 0.001) carnitine palmitoyltransferase-1 beta (CPT1β) gene expression, but the increase in CPT1β gene expression was especially pronounced in IPA incubated with palmitic and stearic acid (6- to 17- fold increases). Oleic and linoleic acid decreased (p = 0.001) stearoyl-CoA desaturase (SCD) gene expression over 80% in both BSC and IPA. Conversely, palmitic and stearic acid increased SCD gene expression three fold in co-cultured in IPA, and stearic acid increased AMPKα gene expression in single- and co-cultured BSC and IPA. Consistent with our hypothesis, saturated fatty acids, especially stearic acid, promoted adipogenic and lipogenic gene expression, whereas unsaturated fatty acids decreased expression of those genes associated with fatty acid metabolism.

Biological responses of beef steers to steroidal implants and zilpaterol hydrochloride

British × Continental steers (n = 168; 7 pens/treatment; initial BW = 362 kg) were used to evaluate the effect of dose/payout pattern of trenbolone acetate (TBA) and estradiol-17β (E2) and feeding of zilpaterol hydrochloride (ZH) on serum urea-N (SUN), NEFA, IGF-I, and E2 concentrations and LM mRNA expression of the estrogen (ER), androgen (ANR), IGF-I (IGF-IR), β1-adrenergic (β1-AR), and β2-adrenergic (β2-AR) receptors and IGF-I. A randomized complete block design was used with a 3 × 2 factorial arrangement of treatments. Main effects were implant (no implant [NI], Revalor-S [REV-S; 120 mg TBA + 24 mg E2], and Revalor-XS [REV-X; 200 mg TBA + 40 mg E2]) and ZH (0 or 8.3 mg/kg of DM for 20 d with a 3-d withdrawal). Steers were fed for 153 or 174 d. Blood was collected (2 steers/pen) at d -1, 2, 6, 13, 27, 55, 83, 111, and 131 relative to implanting; LM biopsies (1 steer/pen) were collected at d -1, 27, 55, and 111. Blood and LM samples were collected at d -1, 11, and 19 relative to ZH feeding. A greater dose of TBA + E2 in combination with ZH increased ADG and HCW in an additive manner, suggesting a different mechanism of action for ZH and steroidal implants. Implanting decreased (P < 0.05) SUN from d 2 through 131. Feeding ZH decreased (P < 0.05) SUN. Serum NEFA concentrations were not affected by implants (P = 0.44). There was a day × ZH interaction (P = 0.06) for NEFA; ZH steers had increased (P < 0.01) NEFA concentrations at d 11 of ZH feeding. Serum E2 was greater (P < 0.05) for implanted steers by d 27. Serum trenbolone-17β was greater (P < 0.05) for implanted steers by d 2 followed by a typical biphasic release rate, with a secondary peak at d 111 for REV-X (P < 0.05) implanted steers. Implanting did not affect mRNA expression of the ANR or ER, but the IGF-IR and the β1-AR and β2-AR were less (P < 0.05) for REV-S than NI at d 55 and β2-AR mRNA was less (P < 0.05) for REV-S than for REV-X. Expression of the IGF-IR and the β1-AR at d 111 was greater (P< 0.05) for REV-X than for REV-S and NI at d 111, and the β2-AR was less (P< 0.05) for REV-S than for REV-X. Feeding ZH did not affect mRNA expression of the β1-AR and β2-AR. Both implanting and feeding ZH decreased SUN, but a greater dose of TBA + E2 did not result in further decreases. In addition, feeding ZH increased serum NEFA concentrations. Metabolic changes resulting from implanting and feeding ZH may aid in explaining steer performance and carcass responses to these growth promotants.

Contact angles on surfaces using mean field theory: nanodroplets vs. nanoroughness

With emerging systems and applications accessing features within the nanoregime, whether due to droplet size or feature size, understanding the wetting behaviours of these materials is an area of ongoing interest. Theoretical studies, providing a fundamental understanding of how contact angle behaviour changes at these length scales, are important to further such work. This study provides a comprehensive examination of the application of lattice density functional theory (LDFT) to a pillared surface to confirm the suitability of LDFT for studying more complex surfaces. Incorporation of the correct level of details for the fluid-wall interaction was found to produce all of the qualitative changes that have been observed in off-lattice theories. Though previous reports have provided apparently conflicting results, the more comprehensive examination of feature sizes provided here demonstrates that those behaviours are consistent with one another. The well-studied failure of macroscopic models that results from non-negligible line tension contributions and small droplets to feature size ratios was demonstrated using LDFT. Furthermore, the failure of macroscopic models resulting upon reduction in feature size, which has been considered less often, is clearly demonstrated. A key assumption of the macroscopic models is the consistent interaction between surface and fluid regardless of the flatness or roughness of the surface. The density functional results presented here show that, for the smallest features, this is not the case and demonstrate that macroscopic models do not predict the correct contact angle for droplets of any size on nanorough surfaces.

U. S. consumer perceptions of U. S. and Canadian beef quality grades

A U.S. consumer (n = 642) study (Baltimore, MD; Phoenix, AZ; and Lubbock, TX) was conducted to compare consumer sensory scores of U.S. beef (83 USDA Choice [Choice] and 96 USDA Select [Select]) and Canadian beef (77 AAA and 82 AA) strip loins. Strip loins (n = 338) were obtained from beef processors in Canada and the United States and were wet aged until 21 d postmortem at 2°C. Marbling scores were assigned at 21 d and loins were paired according to quality grades and marbling score. Strip loins were fabricated into 2.54-cm thick steaks; steaks were vacuum packaged and frozen until further evaluations. Proximate analysis was performed to compare fat, moisture, and protein. Choice and Canadian AAA had similar marbling scores and intramuscular fat. Both Choice and Canadian AAA had greater (P < 0.05) marbling scores and intramuscular fat than Canadian AA, but Select strip loins had intermediate values that were not different from any of the other grades (P > 0.05). Consumers' opinions did not differ when comparing equivalent grades (Choice with Canadian AAA and Select with Canadian AA), but they rated Choice and Canadian AAA more palatable than Select and Canadian AA for all sensory attributes (P < 0.05). Regarding percentage of acceptability and likelihood to buy score, consumers indicated a preference and greater probability to buy (P = 0.001 and P = 0.004, respectively) strip loin steaks from higher quality grade carcasses (Choice and Canadian AAA) than lower quality grade carcasses (Select and Canada AA). Additionally, consumers gave their opinion of Canadian beef, where its quality and safety were rated as "good" to "excellent" for both attributes (76.72% and 88.36%, respectively; P < 0.05), feeling confident in beef that is imported from Canada. In the same way, consumers indicated that country-of-origin labeling was a minimal factor influencing their beef steak purchasing decisions. Results from this consumer study indicated U.S. consumers could not differentiate between U.S. and Canadian beef within comparable quality grades; however, strip loin steaks from higher quality grades were more palatable than lower quality grades according to consumer scores for eating quality traits.

Successional mosquito dynamics in surrogate treehole and ground-container habitats in the northeastern United States: where does Aedes albopictus fit in?

This study assessed the risk of larval displacement of the eastern treehole mosquito, Aedes triseriatus, and the northern house mosquito, Culex pipiens, by Aedes albopictus, the Asian tiger mosquito, during the establishment and successional stages of novel larval mosquito treehole and ground-container habitats in the state of New Jersey, U.S.A. Culex pipiens and Culex restuans were the first mosquito species to colonize ground-container habitats and were the dominant larval species throughout the study period, whereas Ae. albopictus was late to colonize ground habitats and accounted for less than 15% of weekly larval collections once established. Ae. albopictus had a much stronger community presence within treehole ovitraps; however, Ae. albopictus never reached the average larval densities of the expected primary colonizer, Ae. triseriatus. Throughout the study period, the weekly abundances of Ae. triseriatus and Ae. albopictus were positively correlated and there were no significant differences between the abundances of each species. The larval dominance of Ae. triseriatus appears to be enhanced by the presence of Toxorhynchites rutilus septentrionalis, a large predatory mosquito species. When Tx. rut. septentrionalis was present, mature larvae (3(rd) -4(th) instar) of Ae. albopictus were also present in only 16.7% of collections, whereas mature larvae of Ae. triseriatus were collected concurrently with Tx. rut. septentrionalis in 53.8% of collections. These data suggest that Ae. triseriatus is at a greater risk of displacement by Ae. albopictus than are Cx. pipiens and Cx. restuans.

Fatty acid biosynthesis and lipogenic enzyme activities in subcutaneous adipose tissue of feedlot steers fed supplementary palm oil or soybean oil

We hypothesized that supplementing finishing diets with palm oil would promote adipocyte differentiation in subcutaneous adipose tissue of feedlot steers, and that soybean oil supplementation would depress adipocyte differentiation. Twenty-eight Angus steers were assigned randomly to 3 groups of 9 or 10 steers and fed a basal diet without additional fat (control), with 3% palm oil (rich in palmitic acid), or with 3% soybean oil (rich in polyunsaturated fatty acids), for 10 wk, top-dressed daily. Palm oil had no effect (P > 0.05) on ADG, food intake, or G:F, whereas soybean oil depressed ADG (P = 0.02), food intake (P = 0.04), and G:F (P = 0.05). Marbling scores tended (P = 0.09) to be greater in palm oil-fed steers (Modest(09)) than in soybean oil-fed steers (Small(55)). Subcutaneous adipocyte mean volume was greater in palm oil-fed steers (515.9 pL) than in soybean-supplemented cattle (395.6 pL; P = 0.01). Similarly, glucose and acetate incorporation into total lipids in vitro was greater in subcutaneous adipose tissue of palm oil-fed steers (119.9 and 242.8 nmol·3h(-1)·10(5) cells, respectively) than adipose tissue of soybean oil-fed steers in (48.9 and 95.8 nmol·3h(-1)·10(5) cells, respectively). Glucose-6-phosphate dehydrogenase and NADP-malate dehydrogenase activities were greater (P ≤ 0.05) in subcutaneous adipose tissue of palm oil-fed steers than in adipose tissue of control steers. Palm oil did not increase palmitic acid or decrease oleic acid in subcutaneous adipose tissue or LM, but decreased (P ≤ 0.05) myristoleic, palmitoleic, and cis-vaccenic acid in adipose tissue, indicating a depression in stearoyl-coenzyme A desaturase activity. Soybean oil increased the proportion of α-linolenic acid in adipose tissue and muscle and increased linoleic acid and 18:1trans-10 in muscle. We conclude that palm oil supplementation promoted lipid synthesis in adipose tissue without depressing feed efficiency or increasing the palmitic acid content of beef.

Drought-induced amplification of local and regional West Nile virus infection rates in New Jersey

ABSTRACT This study looked at the influence of interannual variations in temperature and precipitation on seasonal mosquito abundances, the prevalence of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in the northeastern United States, and the capacity for local mosquito communities to maintain and transmit WNV, defined as vector community competence. Vector and virus surveillance took place within Middlesex County in New Jersey over two transmission seasons (2010 and 2011). Drought conditions during the 2010 season were associated with significant increases in the number of blood-fed Culex spp. mosquitoes collected per week, and significant increases in vector community competence, or the ability of local vector communities to transmit WNV, when compared with the wetter and milder 2011 season. These increases were associated with significantly higher weekly WNV infection rates in Culex spp. (i.e., Culex pipiens L. and Culex restuans L.) during the 2010 drought season. On a larger scale, the positive influence of drought on the amplification of WNV was also confirmed at the state level where early seasonal (June-July) increases in temperature and decreases in precipitation were strongly correlated with increases in yearly WNV infection rates over a 9-yr period (2003-2011). These data suggest that there may be clear temperature and precipitation thresholds beyond which epidemic levels of WNV transmission occur.

Administration of estradiol, trenbolone acetate, and trenbolone acetate/estradiol implants alters adipogenic and myogenic gene expression in bovine skeletal muscle

Twenty crossbred yearling steers (421 kg) were used to evaluate the effects of implanting with trenbolone acetate (TBA; 120 mg), estradiol-17β (E(2); 25.7 mg), and a combination (120 mg of TBA and 24 mg of E(2)) on adipogenic and myogenic mRNA concentrations. Animals were blocked by BW and within each block were assigned to 1 of 4 treatments. Animals were housed and fed in individual pens with 5 animals per treatment. All animals were weighed weekly, and muscle biopsy samples were taken from the LM of each steer on d 0 (before implantation), 7, 14, and 28. Total RNA was isolated from each sample and real-time quantitative PCR was used to measure the quantity of C/EBPβ, PPARγ, stearoyl CoA desaturase (SCD), myogenin, and 3 isoforms of bovine myosin heavy chain (MHC) mRNA. Total BW gain from the 28-d period was adjusted to d 0 by use of covariant analysis, and steers in the implant groups tended (P = 0.09) to have increased BW gain compared with nonimplanted control steers. Analysis of the gene expression of MHC showed that neither implant nor day (P > 0.20) had a significant effect on the expression of type I or IIX MHC mRNA There was also no treatment effect (P > 0.20) on MHC-IIA and myogenin, but increasing days on feed increased (P = 0.05) the expression of MHC-IIA mRNA. Relative mRNA abundance of C/EBPβ, PPARγ, and SCD increased (P < 0.05) during days of feed but PPARγ decreased (P < 0.05) with the treatment of combined TBA/E(2) implant. Results of this study indicate that implanting with TBA, E(2), or both increased BW gain and decreased adipogenic gene expression of finishing steers without significantly affecting the concentration of type I, IIA, or IIX MHC mRNA. Increasing days on feed increased both MHC-IIA and adipogenic gene expression in bovine skeletal muscle biopsy samples. We conclude that administration of steroidal implants had no effect on the proportion of the 3 MHC mRNA isoforms but decreased C/EBPβ, PPARγ, and SCD mRNA in bovine skeletal muscle.

Effects of zilpaterol hydrochloride and days on the finishing diet on feedlot performance, carcass characteristics, and tenderness in beef heifers

British × Continental heifers (n = 3,382; initial BW = 307 kg) were serially slaughtered to determine if increasing days on the finishing diet (DOF) mitigates negative consequences of zilpaterol HCl (ZH) on quality grade and tenderness of beef. A 2 × 3 factorial arrangement of treatments in a completely randomized block design (36 pens; 6 pens/treatment) was used. Zilpaterol HCl (8.33 mg/kg DM) was fed 0 and 20 to 22 d before slaughter plus a 3 to 5 d withdrawal to heifers spending 127, 148, and 167 DOF. Feedlot and carcass performance data were analyzed with pen as the experimental unit. Three hundred sixty carcasses (60 carcasses/treatment) were randomly subsampled, and strip loin steaks were aged for 7, 14, and 21 d for assessment of Warner-Bratzler shear force (WBSF) and slice shear force (SSF) with carcass serving as the experimental unit for analysis. No relevant ZH × DOF interactions were detected (P > 0.05). Feeding ZH during the treatment period increased ADG by 9.5%, G:F by 12.5%, carcass ADG by 33.6%, carcass G:F by 35.9%, carcass ADG:live ADG by 15.6%, HCW by 3.2% (345 vs. 356 kg), dressing percent by 1.5%, and LM area by 6.5% and decreased 12th-rib fat by 5.2% and yield grade (YG) by 0.27 units (P < 0.01). Feeding ZH tended to decrease marbling score (437 vs. 442 units; P = 0.10) and increased WBSF at 7 (4.25 vs. 3.47 kg; P < 0.01), 14 (3.57 vs. 3.05 kg; P < 0.01), and 21 d (3.50 vs. 3.03 kg; P < 0.01). Feeding ZH decreased empty body fat percentage (EBF; 29.7% vs. 30.3%; P < 0.01) and increased 28% EBF adjusted final BW (473.4 vs. 449.8 kg; P < 0.01). Analysis of interactive means indicated that the ZH × 148 DOF group had a similar percentage of USDA Prime, Premium Choice, Low Choice, and YG 1, 2, 3, 4, and 5 carcasses (P > 0.10) and decreased percentage of Select (30.4 vs. 36.6%; P = 0.03) and Standard (0.2 vs. 0.9%; P = 0.05) carcasses compared with the control × 127 DOF group. As a result of ZH shifting body composition, extending the DOF of beef heifers is an effective feeding strategy to equalize carcass grade distributions. This can be accomplished along with sustaining the ZH mediated advantages in feedlot and carcass weight gain.

Effects of postmortem calcium chloride injection on meat palatability traits of strip loin steaks from cattle supplemented with or without zilpaterol hydrochloride

An experiment was conducted to determine the effects of zilpaterol hydrochloride mM supplementation (ZH; 8.3 mg/kg on a DM basis for 20 d) and calcium chloride injection [CaCl(2), 200 at 5% (wt/wt) at 72 h postmortem] on palatability traits of beef (Bos taurus) strip loin steaks. Select (USDA) strip loins were obtained from control (no ZH = 19) and ZH-supplemented carcasses (n = 20). Right and left sides were selected alternatively to serve as a control (no INJ) or CaCl(2)-injected (INJ) and stored at 4°C. Before injecting the subprimals (72 h postmortem), 2 steaks were cut for proximate, sarcomere length, and myofibrillar fragmentation index (MFI) analyses. At 7 d postmortem each strip loin was portioned into steaks, vacuum packaged, and aged for the appropriate period for Warner-Bratzler shear force (WBSF; 7, 14, 21, and 28 d postmortem), trained sensory analysis (14 and 21 d postmortem), purge loss (7 d), and MFI (3, 7, 14, 21, and 28 d postmortem). Results indicated steaks from both ZH supplementation and INJ had reduced WBSF values as days of postmortem aging increased. The WBSF values of ZH steaks were greater (P < 0.05) than no ZH steaks at each postmortem aging period. The INJ steaks had lower WBSF values (P < 0.05) than non-injected steaks. A greater percentage (91 vs. 71%) of steaks had WBSF values < 4.6 kg from steers with no ZH supplementation at 7 d postmortem, but the percentage did not differ (P > 0.05) due to ZH at 14, 21, or 28 d or due to INJ at any aging period. Trained panelists rated tenderness less in ZH steaks than steaks with no ZH at 14 d and 21 d. However, INJ improved (P < 0.05) the tenderness ratings and flavor intensity of the trained panelists, compared with their non-injected cohorts at 21 d. Zilpaterol hydrochloride supplementation reduced (P < 0.05) MFI values, but INJ resulted in greater (P < 0.05) MFI values compared with no INJ. Subprimals from ZH and INJ showed greater purge loss (P < 0.05). Although no interactions were found with ZH and CaCl(2), injecting USDA Select strip loins from ZH-fed cattle can help reduce the normal WBSF variation as it does in steaks from non-ZH-fed cattle.

Adipogenic gene expression and fatty acid composition in subcutaneous adipose tissue depots of Angus steers between 9 and 16 months of age

We have demonstrated that among carcass adipose tissue depots, brisket subcutaneous adipose tissue contains the greatest concentration of MUFA and lowest concentration of SFA. Therefore, we hypothesized that brisket subcutaneous adipose tissue depots would exhibit greater adipogenic gene expression over time than other major subcutaneous adipose tissue depots. Four Angus steers, each at 9, 12, 14, and 16 mo of age, were harvested and fresh subcutaneous adipose tissue samples were collected from over the brisket, chuck, rib, loin, sirloin, round, flank, and plate. Relative gene expression for C/EBPβ, PPARγ, carnitine palmitoyltransferase-1 beta (CPT-1β), stearoyl-coenzyme A desaturase (SCD), AMP-activated protein kinase alpha (AMPKα), and G-coupled protein receptor 43 (GPR43) was analyzed by quantitative real-time PCR. Expression of C/EBPβ, PPARγ, and CPT-1β was greatest at 12 to 14 mo of age (all P < 0.0001) and declined to very low abundance by 16 mo of age in all depots. Expression of PPARγ and CPT-1β was greater (P < 0.03) in flank, rib, and sirloin subcutaneous adipose tissues than in brisket and round adipose tissues. The expression of the SCD gene did not differ among the 4 age groups (P = 0.95). The palmitoleic:stearic acid ratio (an estimate of SCD activity) was greater (P < 0.001) in the subcutaneous adipose tissues from brisket, plate, and round than in the loin, rib, and sirloin. Conversely, subcutaneous adipose tissue from the loin, rib, and sirloin had greater (P < 0.001) SCD gene expression than the brisket, plate, and round. In general, subcutaneous adipose tissues with the highest concentration of MUFA and least SFA consistently exhibited the least SCD gene expression and adipogenic gene expression. We conclude that MUFA in the brisket and other depots with large SCD indices were deposited before 9 mo of age, during a time when the subcutaneous adipocytes were highly differentiated.

Effects of sequential feeding of β-adrenergic agonists on cull cow performance, carcass characteristics, and mRNA relative abundance

The objectives of this study were to determine the effects of supplementation with a single β-adrenergic agonist (β-AA) or a sequence of β-AA on cow performance, carcass characteristics, and mRNA relative abundance of cull cows implanted and fed a concentrate diet. Sixty cull cows were implanted with Revalor-200 (200 mg of trenbolone acetate and 20 mg of estradiol) and assigned to 1 of 4 treatments (n = 15/treatment): CON = fed a concentrate diet only; RH = supplemented with ractopamine-HCl for the last 25 d before slaughter; ZH = supplemented with zilpaterol-HCl for 20 d before a 3-d withdrawal before slaughter; RH + ZH = supplemented with RH for 25 d, followed by ZH for 20 d before a 3-d withdrawal before slaughter. Ractopamine-HCl was supplemented at a dose of 200 mg·animal(-1)·d(-1), and ZH was supplemented at 8.33 mg/kg (100% DM basis) of feed. All cows were fed a concentrate diet for 74 d. Each treatment had 5 cows per pen and 3 replicate pens. Body weights were collected on d 1, 24, 51, and 72. Muscle biopsies from the LM were collected on d 24, 51, and at slaughter from a subsample of 3 cows per pen. Carcass traits were evaluated postslaughter. The 2 ZH treatments averaged 15.3 kg more BW gain, 0.20 kg greater ADG, and 7.8 cm(2) larger LM area than CON and RH treatments, and 21 kg more HCW than CON, but these differences were not significant (P > 0.10), likely due to a sample size of n = 15/treatment. The sequence of RH followed by ZH tended to optimize the combination of HCW, LM area, percent intramuscular fat, and lean color and maturity compared with the ZH treatment. Abundance of β(2)-adrenergic receptor (AR) mRNA was not altered in the RH + ZH treatment during RH supplementation from d 24 to 51 of feeding. However, the abundance of β(2)-AR mRNA increased (P < 0.05) the last 23 d of feeding for the RH treatment and tended (P = 0.10) to increase in ZH cows during ZH supplementation. For all cows, abundance of type IIa myosin heavy chain (MHC-IIa) mRNA decreased (P < 0.05) after 24 d of feeding. Abundance of MHC-IIx mRNA increased (P < 0.05) for ZH and RH + ZH treatments the last 23 d of feeding during ZH supplementation. Although few significant differences were observed in performance or carcass traits, mRNA quantification indicated that β-AA supplementation elicited a cellular response in cull cows. Implanting and feeding cull cows for 74 d, regardless of β-AA supplementation, added economic value by transitioning cows from a cull cow to what is referred to in industry as a white cow market in which cows have white fat resulting from grain feeding.

Zilpaterol hydrochloride alters abundance of β-adrenergic receptors in bovine muscle cells but has little effect on de novo fatty acid biosynthesis in bovine subcutaneous adipose tissue explants

We predicted that zilpaterol hydrochloride (ZH), a β-adrenergic receptor (AR) agonist, would depress mRNA and protein abundance of β-AR in bovine satellite cells. We also predicted that ZH would decrease total lipid synthesis in bovine adipose tissue. Bovine satellite cells isolated from the semimembranosus muscle were plated on tissue culture plates coated with reduced growth factor matrigel or collagen. Real-time quantitative PCR was used to measure specific gene expression after 48 h of ZH exposure in proliferating satellite cells and fused myoblasts. There was no effect of ZH dose on [(3)H]thymidine incorporation into DNA in proliferating myoblasts. Zilpaterol hydrochloride at 1 µM decreased (P < 0.05) β1-AR mRNA, and 0.01 and 1 µM ZH decreased (P < 0.05) β2-AR and β3-AR mRNA in myoblasts. The expression of IGF-I mRNA tended to increase (P = 0.07) with 1 µM ZH. There was no effect (P > 0.10) of ZH on the β-AR or IGF-I gene expression in fused myotube cultures at 192 h or on fusion percentage. The β2-AR antagonist ICI-118, 551 at 0.1 µM attenuated (P < 0.05) the effect of 0.1 µM ZH to reduce expression of β1- and β2-AR mRNA. The combination of 0.01 µM ZH and 0.1 µM ICI-118, 551 caused an increase (P < 0.05) in β1-AR gene expression. There was no effect (P > 0.10) of ICI-118, 551 or ZH on β3-AR or IGF-I. Western blot analysis revealed that the protein content of β2-AR in ZH-treated myotube cultures decreased (P < 0.05) relative to control. Total lipid synthesis from acetate was increased by ZH in bovine subcutaneous adipose tissue explants in the absence of theophylline but was decreased by ZH when theophylline was included in the incubation medium. These data indicate that ZH alters mRNA and protein concentrations of β-AR in satellite cell cultures, which in turn could affect responsiveness of cells to prolonged ZH exposure in vivo. Similar to other β-adrenergic agonists, ZH had only modest effects on lipid metabolism in adipose tissue explants.

A search for socio-economic influences in behaviour and attitudes to medicines available for self-medication and NHS prescription

Focal points

Effects of supplementing feedlot steers and heifers with zilpaterol hydrochloride on Warner-Bratzler shear force interrelationships of steer and heifer longissimus lumborum and heifer triceps brachii and gluteus medius muscles aged for 7, 14 and 21d

Longissimus lumborum (LL) muscles from 117 steers plus LL, gluteus medius (GM), and triceps brachii (TB) muscles from 132 heifers were evaluated for effects of feeding duration of zilpaterol hydrochloride (Zilmax(R); ZH; 7.56g/907kg on a dry matter basis) and aging time on tenderness. Both genders were blocked by initial weight into six blocks of four pens. Pens were assigned to treatments of control (C), or 20, 30 or 40days on ZH, with a 3day withdrawal. Steaks from each subprimal were vacuum aged individually for 7, 14 or 21days, frozen, thawed, and cooked to 71 degrees C for Warner-Bratzler shear force (WBSF). All muscles from steers and heifers from ZH30 and ZH40 treatments had higher (P<0.05) WBSF than those of C. The WBSF of steer LL and heifer TB from the ZH20 treatment was higher (P<0.05) than C. There was a treatment by aging interaction (P>0.05) for WBSF of GM steaks from heifers. Percentage of intramuscular fat had little effect on tenderness. Percentages of steer LL and heifer TB steaks with WBSF values below thresholds of either 5.0 or 4.6kg from the ZH20 treatment were quite high, whereas percentages of heifer LL and GM muscles below 5.0kg (67%) and 4.6kg (57%) were low. Feeding ZH20days generally increased WBSF values, but mean WBSF values for steer LL and heifer TB were below 4.6kg. Feeding ZH 20days resulted in>40% of GM steaks with WBSF values above 4.6kg.

Tissue expression of angiopoietin-like protein 4 in cattle

Angiopoietin-like protein 4 (ANGPTL4; also known as fasting-induced adipose factor) is a plasma protein that stimulates oxidation of fatty acids and inhibits fat accumulation. The gastrointestinal tract appears to play an important role in regulating plasma ANGPTL4 concentration in some situations and may be influenced by microbes within the gastrointestinal tract. Our aim was to determine which tissues express ANGPTL4 in the bovine. Rumen, omasum, abomasum, duodenum, jejunum, ileum, colon, pancreas, liver, and subcutaneous adipose tissue samples were collected postmortem from 2 steers. Abundance of ANGPTL4 messenger RNA was quantified by quantitative real-time PCR, and was most abundant in liver and adipose tissue (P < 0.05). We also detected ANGPTL4 messenger RNA throughout the gastrointestinal tract, although its abundance was approximately 10% of that found in liver and adipose tissue. Western blot analysis revealed that ANGPTL4 protein was most abundant in liver and adipose tissue (P < 0.05), but omasal, abomasal, and ileal samples contained at least 60% as much ANGPTL4 protein as the liver and adipose tissue samples, and the protein was detected in all tissues. Finally, cross-sections of the liver, pancreas, and rumen wall were used for indirect immunofluorescent detection of ANGPTL4. Despite the low abundance of ANGPTL4 measured by quantitative real-time PCR and Western blot in ruminal tissue, immunofluorescence demonstrated that expression of ANGPTL4 in ruminal epithelial cells was equivalent to or greater than that in liver hepatocytes. These findings indicate that, as in other species studied, liver and adipose tissue are key sources of ANGPTL4 in cattle. However, the protein was also highly abundant in ruminal epithelium, making it possible that commensal microbes may influence ANGPTL4 synthesis and secretion in the ruminant gastrointestinal tract.

Effects of duration of zilpaterol hydrochloride and days on the finishing diet on carcass cutability, composition, tenderness, and skeletal muscle gene expression in feedlot steers

Preselected carcasses (n = 112) from feedlot steers fed zilpaterol hydrochloride (ZH; 8.33 mg/kg, DM basis) in a serial slaughter experiment were evaluated to determine the effects of ZH upon carcass cutability, composition, and tenderness. A 4 x 4 factorial arrangement of treatments in a completely random design was used with days on ZH (0, 20, 30, and 40 d before slaughter with a 3-d withdrawal) and days on the finishing diet (DOF; 136, 157, 177, and 198 d). No relevant ZH duration x slaughter group interactions were detected (P > 0.05) for carcass cutability, composition, or tenderness data. Exposure to ZH increased the lean yield of 22 of the 33 subprimals evaluated with every subprimal within the round showing increased cutability (P < or = 0.04). Carcass fat was decreased, whereas carcass protein and moisture were increased due to ZH (P < 0.01). Lengthening the ZH feeding period did not result in additive gains in subprimal yield or chemical composition (P > 0.05). Warner-Bratzler shear force analysis of the LM indicated that ZH caused a toughening effect (P < 0.01) regardless of the length of the aging period (7, 14, or 21 d). Extending the ZH dose duration caused a linear increase in Warner-Bratzler shear force at 7 (P = 0.06) and 21 d (P < 0.01) of aging. Within 10 min postmortem, samples (n = 48) were collected from the semimembranosus muscle for RNA isolation from 4 randomly selected steers from each treatment within the 157, 177, and 198 d slaughter groups. Feeding ZH did not alter beta1- or beta2-adrenergic receptor (AR), calpastatin (CAL), IGF-I, or myosin heavy chain (MHC) isoform I mRNA abundance (P > 0.10). There was a ZH duration x DOF interaction (P < 0.01) for the expression of MHC-IIa and -IIx. Expression of MHC-IIa was decreased in every ZH treatment within the 177 and 198 DOF groups (P < 0.02). Expression of MHC-IIx was increased in the 20-d ZH group in the 157 DOF group (P = 0.03), and the 40-d ZH group in the 177 (P = 0.10) and 198 (P = 0.03) DOF groups. There was a tendency for a linear decrease in CAL mRNA abundance as ZH duration increased (P = 0.07), and there was a linear increase in beta2-AR (P = 0.03) and CAL (P < 0.01) mRNA abundance as DOF increased. Collectively, the data indicate that ZH may influence net protein turnover by decreasing MHC-IIa mRNA transcription and possibly increasing MHC-IIx. Furthermore, a ZH feeding duration of 20 d appeared to be adequate for capturing lean yield benefits while limiting tenderness losses.

Systemic reactive angioendotheliomatosis-like syndrome in a steer presumed to be persistently infected with bovine viral diarrhea virus

Unusual proliferative intravascular lesions were seen in multiple organs of a 2-year-old Corriente steer presumed to be persistently infected with bovine viral diarrhea virus (BVDV), based on widespread immunohistochemical detection of BVDV antigen. Proliferations of spindle cells, which were immunohistochemically positive for von Willebrand factor-related antigen, partially-to-completely occluded vessel lumens and were supported by cells that were immunohistochemically positive for smooth muscle actin. Distribution and character of the intraluminal proliferations are strikingly similar to those described in feline systemic reactive angioendotheliomatosis, a rare entity of unknown cause. The presence of occasional intravascular thrombi suggests that the proliferative vasculopathy was associated with an underlying thrombotic process with immunohistochemical similarities to thrombotic thrombocytopenic purpura of humans. Death of the steer was due to hemorrhage from a castration wound, which may indicate thrombocytopenia or platelet dysfunction. The role of persistent BVDV infection in the formation of the intravascular lesions is unknown.

Omega-3 fatty acids in the gravid pig uterus as affected by maternal supplementation with omega-3 fatty acids

Two experiments evaluated the ability of maternal fatty acid supplementation to alter conceptus and endometrial fatty acid composition. In Exp. 1, treatments were 1) the control, a corn-soybean meal diet; 2) flax, the control diet plus ground flax (3.75% of diet); and 3) protected fatty acids (PFA), the control plus a protected fish oil source rich in n-3 PUFA (Gromega, JBS United Inc., Sheridan, IN; 1.5% of diet). Supplements replaced equal parts of corn and soybean meal. When gilts reached 170 d of age, PG600 (PMSG and hCG, Intervet USA, Millsboro, DE) was injected to induce puberty, and dietary treatments (n = 8/treatment) were initiated. When detected in estrus, gilts were artificially inseminated. On d 40 to 43 of gestation, 7 gilts in the control treatment, 8 gilts in the PFA treatment, and 5 gilts in the flax treatment were pregnant and were slaughtered. Compared with the control treatment, the flax treatment tended to increase eicosapentaenoic acid (EPA: C20:5n-3) in fetuses (0.14 vs. 0.25 +/- 0.03 mg/g of dry tissue; P = 0.055), whereas gilts receiving PFA had more (P < 0.05) docosahexaenoic acid (DHA: C22:6n-3) in their fetuses (5.23 vs. 4.04 +/- 0.078 mg/g) compared with gilts fed the control diet. Both the flax and PFA diets increased (P < 0.05) DHA (0.60, 0.82, and 0.85 +/- 0.078 mg/g for the control, flax, and PFA diet, respectively) in the chorioallantois. In the endometrium, EPA and docosapentaenoic acid (C22:5n-3) were increased by the flax diet (P < 0.001; P < 0.05), whereas gilts receiving PFA had increased DHA (P < 0.001). The flax diet selectively increased EPA, and the PFA diet selectively increased DHA in the fetus and endometrium. In Exp. 2, gilts were fed diets containing PFA (1.5%) or a control diet beginning at approximately 170 of age (n = 13/treatment). A blood sample was collected after 30 d of treatment, and gilts were artificially inseminated when they were approximately 205 d old. Conceptus and endometrial samples were collected on d 11 to 19 of pregnancy. Plasma samples indicated that PFA increased (P < 0.005) circulating concentrations of EPA and DHA. Endometrial EPA was increased (P < 0.001) for gilts fed the PFA diet. In extraembryonic tissues, PFA more than doubled (P < 0.001) the EPA (0.13 vs. 0.32 +/- 0.013 mg/g) and DHA (0.39 vs. 0.85 +/- 0.05 mg/g). In embryonic tissue on d 19, DHA was increased (P < 0.05) by PFA (0.20 vs. 0.30 +/- 0.023 mg/g). Supplementing n-3 PUFA, beginning 30 d before breeding, affected endometrial, conceptus, and fetal fatty acid composition in early pregnancy. Dynamic day effects in fatty acid composition indicate this may be a critical period for maternal fatty acid resources to affect conceptus development and survival.

Potential role of G-protein-coupled receptor 30 (GPR30) in estradiol-17beta-stimulated IGF-I mRNA expression in bovine satellite cell cultures

Androgenic and estrogenic steroids enhance muscle growth in animals and humans. Estradiol-17beta (E2) and trenbolone acetate (TBA) (a synthetic testosterone analog) increased IGF-I mRNA expression in bovine muscle satellite cell (BSC) cultures. The goal of this study was to evaluate the mechanisms responsible for this increase by evaluating the effects of ICI 182 780 (an E2 receptor antagonist), flutamide (an androgen receptor inhibitor), G1 (a GPR30 agonist), and BSA-conjugated E2 on E2 and/or TBA-stimulated IGF-I mRNA expression in BSC cultures. Flutamide completely suppressed TBA-stimulated IGF-I mRNA expression in BSC cultures. ICI 182 780 did not suppress E2-stimulated IGF-I mRNA expression and 100 nM ICI 182 780 enhanced (93%, p<0.05) IGF-I mRNA levels in BSC cultures. G1 (100 nM) stimulated IGF-I mRNA expression (100%, p<0.05) but had no effect on proliferation in BSC cultures. E2-BSA, which cannot cross the cell membrane, stimulated IGF-I mRNA expression (approximately 100%, p<0.05) in BSC but even at extremely high concentrations had no effect on proliferation. In summary, our data indicate the E2-stimulation of proliferation and E2-stimulation of IGF-I mRNA expression in BSC cultures occur via different mechanisms. Our previous results showing that ICI 182 780 inhibited BSC proliferation and results of the current study showing lack of response to E2-BSA or G1 suggest that E2-stimulated proliferation in BSC cultures is mediated through classical estrogen receptors. Stimulation by ICI 182 780, G1 and E2-BSA suggests the E2-stimulated IGF-I mRNA expression in BSC cultures is mediated through the GPR30 receptor.

Roles of IGF-I and the estrogen, androgen and IGF-I receptors in estradiol-17beta- and trenbolone acetate-stimulated proliferation of cultured bovine satellite cells

Although numerous studies have shown that both androgenic and estrogenic steroids increase rate and efficiency of muscle growth in steers, there is little consensus as to their mechanism of action. A combined estradiol 17beta (E2)/trenbolone acetate (TBA) implant causes a significant increase in muscle IGF-I mRNA and both E2 and TBA stimulate a significant increase in IGF-I mRNA level in bovine satellite cell (BSC) cultures in media containing 10% fetal bovine serum (FBS). Consequently, increased IGF-I expression may play a role in anabolic-steroid-enhanced muscle growth. However, even though treatment of cultured BSC with E2 or TBA in media containing 1% IGFBP-3-free swine serum (SS) results in increased proliferation there is no effect on IGF-I mRNA expression, suggesting that increased IGF-I expression may not be responsible for anabolic-steroid-enhanced BSC proliferation. To further examine the role of estrogen, androgen and IGF-I receptors and their respective ligands in E2- and TBA-stimulated BSC proliferation, we assessed the effects of specific inhibitors on E2- or TBA-stimulated proliferation of BSC. Both ICI 182 780 (an estrogen receptor blocker) and flutamide (an inhibitor of androgen receptor) suppressed (p<0.05) E2- and TBA-stimulated BSC proliferation, respectively. JB1 (a competitive inhibitor of IGF-I binding to type I IGF receptor) reduced (p<0.05) both E2- and TBA-stimulated proliferation in BSC cultures. Both the Raf-1/MAPK kinase (MEK)1/2/ERK1/2, and the phosphatidylinositol 3-kinase (PI3K)/Akt pathways play significant roles in the actions of IGF-I on proliferation and differentiation of myogenic cells. PD98059, an inhibitor of the MAPK pathway, and wortmannin, an inhibitor of the PI3K pathway, both suppressed (p<0.05) E2- and TBA-stimulated proliferation of cultured BSC. Our data suggest that IGF-I plays a role in E2- and TBA-stimulated proliferation of cultured BSC even in the absence of increased IGF-I expression.

Effects of steroidal implantation and ractopamine-HCl on nitrogen retention, blood metabolites and skeletal muscle gene expression in Holstein steers

Six Holstein steers (231 +/- 17 kg) housed in metabolism crates were used in a randomized complete block design with three blocks of two steers based on previous serum insulin-like growth factor (IGF)-I concentrations. One of the two steers in each block was implanted with 120 mg trenbolone acetate and 24 mg oestradiol-17beta on day 0. None of the steers was fed ractopamine-HCl in the initial 28 days, and then all steers were fed 200 mg of ractopamine-HCl per steer daily from day 28 until the end of the trial. Steers were fed a corn-based diet (62% rolled corn, 20% expeller soya bean meal and 15% alfalfa hay) twice daily with an average dry matter intake of 4.8 kg/day. Blood and M. longissimus biopsy samples were collected prior to implantation and on days 14, 28, 42 and 56. There was an implant x ractopamine interaction for retained nitrogen (p < 0.05); ractopamine feeding led to only small improvements in nitrogen retention for implanted steers (45.9 g/day vs. 44.5 g/day), whereas ractopamine led to larger increases in nitrogen retention for non-implanted steers (39.0 g/day vs. 30.4 g/day). Implantation increased (p < 0.05) and ractopamine tended to decrease (p = 0.06) serum IGF-I concentrations. Implantation tended to increase (p = 0.16) and ractopamine decreased (p < 0.05) mRNA expression of IGF-I in the M. longissimus. Ractopamine decreased mRNA expression of beta(1)- and beta(2)-receptors in M. longissimus (p </= 0.02). The steroidal implant and the feeding of ractopamine both increased nitrogen retention in steers, but the combination did not yield an additive response. The two growth promotants had opposite effects on serum concentrations of IGF-I and mRNA expression of IGF-I in M. longissimus.

Effects of vitamin A supplementation in young lambs on performance, serum lipid, and longissimus muscle lipid composition

Forty crossbred wethers (BW = 28.7 kg) were used to evaluate the effects on LM lipid composition of diets containing high and low levels of vitamin A. Four treatments arranged as a 2 x 2 factorial with a completely random design were investigated: backgrounding (BG) and finishing (FN) with no supplemental vitamin A (LL); BG with no supplemental vitamin A and FN with high vitamin A (6,600 IU/kg of diet, as fed) supplementation (LH); BG with high vitamin A supplementation and FN with no vitamin A supplementation (HL); and BG and FN with high vitamin A (HH) supplementation. Diets included cracked corn (62.4%), soybean meal (16.0%), cottonseed hull pellets (14.8%), and supplement (7%), and contained <100 IU of vitamin A/kg (as fed) from carotenes before vitamin A was added. During the BG period (d 1 to 56), feed intake was restricted to achieve 0.22 kg of ADG. During the FN period (d 57 to 112), lambs consumed the same diet ad libitum. Lambs were weighed every 14 d, and blood was sampled every 28 d to evaluate changes in serum fatty acids and vitamin A levels. Lambs were slaughtered after 112 d. Lipid composition was determined for liver and LM. There were no treatment differences (P > 0.05) in feed intake, ADG, or final BW. Carcass weights were not affected by vitamin A treatment (P > 0.20), although backfat thickness tended to be different between HL and LL lambs (0.80 vs. 0.64 cm, respectively; P = 0.08). Carcasses from the HH group had greater (P < 0.05) marbling scores than those from the LL group (514 vs. 459) and had 25.8% more extractable intramuscular lipids (3.88 vs. 3.08% for HH and LL, respectively; P < 0.05); the LH and HL treatments were intermediate. Interestingly, the LL group had the greatest increase in serum fatty acids throughout the experimental period (change of 127 vs. 41 microg/g for LL and HH, respectively; P < 0.01). The degree of saturation of fatty acids was not affected by treatment (P = 0.18) in the serum but was affected in the longissimus thoracis fat. Oleic acid increased and linoleic acid decreased in the longissimus thoracis of HH-treated lambs (P < 0.02). These data suggest that increases in total intramuscular lipids may be achieved with high levels of vitamin A supplementation for 112 d in young lambs.

Fibrolytic enzymes to increase the nutritive value of dairy feedstuffs

In vitro studies and a lactation trial were conducted to investigate the effects of fibrolytic enzyme mixtures at different inclusion amounts. Seven enzymes in amounts designed to mimic addition of 1, 5, 15, or 30 g/d to dairy diets were incubated in vitro with either soybean hulls or alfalfa for 24 or 48 h. Enzyme treatments generally increased in vitro dry matter disappearance (IVDMD), but not volatile fatty acid production. For some enzyme mixtures, lesser amounts of enzymes led to greater increases in IVDMD, whereas for others there were no differences among the amounts tested. The enzyme mixture with the most cellulase activity was the most effective enzyme in improving IVDMD. In additional in vitro experiments, the same enzymes were used at an amount of 5 g/d, as well as at other amounts that showed promising responses in the first trial. Preincubation of substrates with enzymes before fermentation also was tested. Alfalfa, soybean hulls, corn silage, and corn gluten feed were used as substrates. Preincubation of the substrate with enzymes for 18 h before in vitro fermentation improved IVDMD. The effect on substrate solubilization of incubating substrates with the enzymes but without rumen fluid was also studied. Addition of enzymes to substrates without subsequent fermentation did not solubilize significant amounts of dry matter, indicating that the positive effect of preincubation cannot be attributed directly to hydrolysis of substrates before the in vitro fermentation with ruminal microbes. The fibrolytic enzyme that appeared most promising in vitro did not affect lactational performance when fed to dairy cows.

Response to ractopamine-HCl in heifers is altered by implant strategy across days on feed1

Two experiments were conducted to investigate the effects of ractopamine-HCl (RAC) and implant strategy or days on feed (DOF) on feedlot performance and expression of beta-adrenergic receptors (AR). In Exp. 1, 1,147 feedlot heifers weighing 282 +/- 3 kg were used with implant treatments of Revalor-200 (R200) at arrival, or Revalor-IH at arrival with reimplantation with Finaplix-H on d 58 (RF). Ractopamine (0 vs. 200 mg/d) was fed the last 28 d in both experiments. Treatments were randomly assigned to 16 pens. At slaughter, semimembranosus muscle tissue was excised for RNA isolation. Ractopamine administration increased (P < 0.05) ADG, G:F, HCW, and LM; decreased (P < 0.05) 12th rib fat depth; and improved (P < 0.05) yield grade. There was no effect (P > 0.10) on the expression of beta1-AR mRNA; however, there was a tendency (P = 0.10) for RAC feeding to increase beta2-AR mRNA levels. For beta3-AR mRNA, there was an implant by RAC interaction (P = 0.05), with RAC numerically increasing beta3-AR mRNA in heifers implanted with RF, but a decrease (P < 0.05) in expression in heifers implanted with R200. Ractopamine also decreased (P < 0.05) IGF-I mRNA in heifers implanted with RF. In Exp. 2, 2,077 heifers were used to investigate the effects of RAC and DOF. Days on feed were 129, 150, and 170, and RAC was administered the last 28 d. Ractopamine improved (P < 0.05) G:F, but had no other effects (P > 0.05) on performance. Average daily gain decreased (P < 0.05) as DOF increased. Hot carcass weight, LM area, 12th rib fat, G:F, calculated yield grade, and marbling score increased (P < 0.05) and the percentage of KPH fat decreased (P < 0.05) as DOF increased. These data aid in our understanding of the effects of steroidal implants, DOF, and RAC administration in feedlot heifers.

Growth characteristics, blood metabolites, and insulin-like growth factor system components in maternal tissues of gilts fed L-carnitine through day seventy of gestation1,2

A total of 59 gilts (BW = 137.7 kg) from 3 breeding groups were used to assess the effects of feeding l-carnitine during gestation on gilt growth characteristics, blood metabolites, and uterine and chorioallantoic expression of IGF axis components at d 40, 55, and 70 of gestation. Experimental treatments were arranged in a 2 x 3 factorial, with main effects of added l-carnitine (0 or 50 ppm) and day after initial breeding (d 40, 55, or 70 of gestation). All gilts received a constant feed allowance of 1.75 kg/d and a top-dress containing 0 or 50 ppm of l-carnitine beginning on the first day of breeding through the assigned day of gestation. No dietary treatment differences were observed for gilt BW, backfat, or estimated protein or fat mass at any day of gestation. No differences were observed in circulating total and free carnitine at breeding, but concentrations increased (P < 0.01) as day of gestation increased for gilts fed diets containing l-carnitine compared with those fed the control diet. Maternal IGF-I concentration decreased (P < 0.01) from d 0 to 70 for all gilts, with no differences between treatments. Insulin-like growth factor binding protein-3 mRNA (P = 0.05) and IGFBP-5 mRNA (P = 0.01) increased in the endometrium of gilts supplemented with l-carnitine. These data demonstrate that l-carnitine supplementation and day of gestation alter the expression of the IGF axis by changing the expression of IGFBP at the fetal-maternal interface in swine. These changes in the IGF axis at the fetal maternal interface may aid in determining the reasons for the effects of l-carnitine on reproductive traits.

Effects of feeding Salmonella enterica serovar Typhimurium or serovar Choleraesuis on growth performance and circulating insulin-like growth factor-I, tumor necrosis factor-α, and interleukin-1β in weaned pigs1

The most common Salmonella serovars causing clinical disease in pigs are Salmonella enterica serovars Typhimurium (Typhimurium) and Choleraesuis. Given that the swine host-adapted serovar Choleraesuis has been reported to cause systemic disease, a different disease outcome from that of Typhimurium, our working hypothesis was that this serovar would likely engage systemic immune-inflammatory mechanisms, resulting in elevated systemic cytokine secretion. Forty-eight weaned pigs were blocked by BW and sex, and randomly allotted to 1 of 3 treatments in a 14-d study. Each treatment had 8 replicates (pens), with 2 pigs/pen. The treatments consisted of a negative control and pigs repeatedly fed 10(8) cfu of Typhimurium or Choleraesuis. On d 0, the pigs were fed Choleraesuis or Typhimurium in dough balls, and the bacteria were refed twice weekly throughout the experiment. Control pigs received dough balls without bacteria. All pigs were housed in temperature-controlled rooms under constant lighting and were fed a standard corn-soybean meal-based nursery diet. Pig BW and feed disappearance were used to determine ADG, ADFI, and G:F. Rectal temperatures were obtained daily from 1 pig/pen beginning 2 d before the first bacterial feeding through d 7 using rapid-response digital thermometers. Serum was collected on d 0, 7, and 14 from a single pig/pen for analysis of IGF-I, tumor necrosis factor-alpha , and IL-1beta. There was no change in the rectal temperature of the control or the Typhimurium-challenged pigs (compared with d 0) or when comparing Typhimurium-challenged pigs with control animals. In contrast, pigs fed Choleraesuis had increased rectal temperatures beginning on d 2 and continuing through d 7 (P < 0.05), with the greatest elevation on d 3 (P < 0.001) compared with the control pigs. Average daily gain and ADFI of pigs challenged with Typhimurium did not differ from those of the control animals. Pigs fed Choleraesuis had a 25% reduction in ADG (P < 0.0001) and ADFI (P < 0.002) compared with the control pigs. On d 7, pigs fed Choleraesuis had reduced serum IGF-I compared with control (P < 0.01) or Typhimurium-challenged pigs (P = 0.01). Bacterial feeding did not affect serum tumor necrosis factor-alpha or IL-1beta compared with control pigs at any time throughout the experiment. We conclude that repeated exposure of weaned pigs to Choleraesuis reduced growth performance in the absence of changes in systemic inflammatory cytokines.

Response to ractopamine-hydrogen chloride is similar in yearling steers across days on feed

Yearling steers (n = 2,552; 314 kg of initial BW) were used to evaluate the effects of ractopamine-HCl (RAC) and days on feed on performance, carcass characteristics, and skeletal muscle gene expression in finishing steers. Treatment groups included serial slaughter dates of 150, 171, or 192 d on feed. Within each slaughter date, steers either received RAC (200 mg/steer) daily for the final 28 d or were not fed RAC. All steers were initially implanted with Revalor-IS and were reimplanted with Revalor-S after 75 d on feed. At slaughter, muscle samples from the semimembranosus were collected for mRNA analysis of the beta-adrenergic receptors (beta-AR). Ractopamine administration increased (P < 0.05) ADG, G:F, and HCW and increased (P = 0.08) LM area. Ractopamine did not affect the dressing percentage, USDA yield grade, or quality grade (P > 0.3). There was no change in overall feed intake across the entire feeding period; however, feed intake was increased during the 28-d period during which the steers were fed RAC (P < or = 0.05). Greater days on feed decreased (P < 0.05) ADG, G:F, DMI, and the number of yield grade 1 and 2 carcasses. Also, greater days on feed increased (P < 0.05) HCW, dressing percentage, and the number of prime and choice carcasses, as well as the number of yield grade 4 and 5 carcasses. Increasing days on feed decreased (P < 0.05) the abundance of beta(1)-AR and beta(3)-AR mRNA and increased (P < 0.05) the abundance of beta(2)-AR mRNA in skeletal muscle samples obtained at slaughter. Ractopamine had no effect (P > 0.10) on the abundance of beta(1)-AR or beta(3)-AR mRNA, but tended (P = 0.09) to increase beta(2)-AR mRNA. Additional time-course studies with primary muscle cell cultures revealed that advancing time in culture increased (P < 0.001) beta(2)-AR mRNA but had no effect (P > 0.10) on beta(1)-AR or beta(3)-AR mRNA. We conclude that days on feed and RAC are affecting beta-AR mRNA levels, which could, in turn, impact the biological response to RAC feeding in yearling steers.

Melengestrol acetate alters muscle cell proliferation in heifers and steers1

In vitro experiments were performed to investigate the effects of melengestrol acetate (MGA) or progesterone (P4) on bovine muscle satellite cells and C2C12 myoblasts. Addition of MGA at physiological and supraphysiological concentrations resulted in a dose-dependent decrease (P < 0.05) in DNA synthesis as measured by [3H]-thymidine incorporation (TI). Similarly, P4 addition (0.01 nM) reduced (P < 0.05) TI. Addition of MGA (10 nM) increased (P < 0.05) IGF-I mRNA abundance but did not affect myogenin mRNA. Progesterone addition (10 nM) increased myogenin mRNA abundance (P < 0.05). In C2C12 cultures, P4 addition resulted in a dose-dependent decrease in TI. The antiprogestin RU486, in combination with MGA or P4, also resulted in reduced (P < 0.05) TI. Treatment with RU486 alone had a negative effect (P < 0.05) on TI that was similar to the progestins. Treatment of C2C12 myoblasts with MGA (100 nM) resulted in an increase (P < 0.05) in myogenin mRNA. These studies suggest that progestins may reduce satellite cell proliferation, ultimately affecting carcass composition.

Effects of L-carnitine on fetal growth and the IGF system in pigs1,2

The effects of L-carnitine on porcine fetal growth traits and the IGF system were determined. Fourth-parity sows were fed a gestation diet with either a 50-g top dress containing 0 (control, n = 6) or 100 mg of L-carnitine (n = 6). At midgestation, fetuses were removed for growth measurements, and porcine embryonic myoblasts (PEM) were isolated from semitendinosus. Real-time quantitative PCR was used to measure growth factor messenger RNA (mRNA) levels in the uterus, placenta, muscle, hepatic tissue, and cultured PEM. A treatment x day interaction (P = 0.02) was observed for maternal circulating total carnitine. Sows fed L-carnitine had a greater (P = 0.01) concentration of total carnitine at d 57 than control sows. Circulating IGF-I was not affected (P = 0.55) by treatment. Supplementing sows with L-carnitine resulted in larger (P = 0.02) litters (15.5 vs. 10.8 fetuses) without affecting litter weight (P = 0.07; 1,449.6 vs. 989.4 g) or individual fetal weight (P = 0.88) compared with controls. No treatment effect was found for muscle IGF-I (P = 0.36), IGF-II (P = 0.51), IGFBP-3 (P = 0.70), or IGFBP-5 (P = 0.51) mRNA abundance. The abundance of IGF-I (P = 0.72), IGF-II (P = 0.34), and IGFBP-3 (P = 0.99) in hepatic tissue was not influenced by treatment. Uterine IGF-I (P = 0.46), IGF-II (P = 0.40), IGFBP-3 (P = 0.29), and IGFBP-5 (P = 0.35) mRNA abundance did not differ between treatments. Placental IGF-I (P = 0.30), IGF-II (P = 0.18), IGFBP-3 (P = 0.94), and IGFBP-5 (P = 0.42) mRNA abundance did not differ between treatments. There was an effect of side of the uterus for IGF-I (P = 0.04) and IGF-II (P = 0.007) mRNA abundance; IGF-I mRNA abundance was greater in the left uterine horn than in the right uterine horn (0.14 and 0.07 relative units, respectively). Placental IGF-II mRNA abundance was greater (P = 0.007) in the left than in the right uterine horn (483.5 and 219.59, respectively). The abundance of IGFBP-3 was not affected by uterine horns in either uterine (P = 0.66) or placental (P = 0.13) tissue. There was no treatment difference for IGF-I (P = 0.31) or IGFBP-5 (P = 0.13) in PEM. The PEM isolated from sows fed L-carnitine had decreased IGF-II (P = 0.02), IGFBP-3 (P = 0.03), and myogenin (P = 0.04; 61, 59, and 67%, respectively) mRNA abundance compared with controls. These data suggest that L-carnitine supplemented to gestating sows altered the IGF system and may affect fetal growth and development.

Effect of flax supplementation and growth promotants on lipoprotein lipase and glycogenin messenger RNA concentrations in finishing cattle1

Lipoprotein lipase (LPL) hydrolyzes triacylglycerols into monoacylglycerol and fatty acids, which are taken up by tissues and used for energy. Glycogenin is the core protein on which glycogen molecules are synthesized. There is one molecule of glycogenin per molecule of glycogen in skeletal muscle; therefore, glycogen storage is limited by the amount of glycogenin present in muscle. The objective of this study was to investigate the effect of feeding flaxseed, a source of PUFA, and administering a growth promoter on steady-state LPL and glycogenin mRNA content of muscle in finishing cattle. Sixteen crossbred steers (initial BW = 397 kg), given ad libitum access to a 92% concentrate diet for 28 d, were used in a four-treatment, 2 x 2 factorial experiment, with flaxseed supplementation (0 or 5% of dietary DM) and implanting (not implanted or implanted with Revalor-S) as the main effects. Muscle biopsies were obtained from the LM at 0, 14, and 28 d, and used to quantify LPL and glycogenin mRNA concentrations using real-time quantitative PCR. Implanting with Revalor-S did not affect LPL (P = 0.13) or glycogenin (P = 0.98) mRNA concentrations. A day x flaxseed interaction (P < 0.001) was observed for both LPL and glycogenin mRNA concentrations. No differences (P > 0.10) were observed between 0 and 5% flaxseed supplemented steers; however, at 28 d, nonflaxseed-fed steers had 4.1- and 5.7-fold increases (P < 0.001) over flaxseed steers for LPL and glycogenin mRNA concentrations, respectively. To further evaluate the effects of alpha-linolenic acid (alpha-LA) on LPL and glycogenin mRNA concentrations, muscle satellite cells were isolated from five finishing steers, and different alpha-LA concentrations were applied in culture. The RNA was isolated from the bovine satellite cells. Addition of alpha-LA numerically increased (P = 0.16) the LPL mRNA concentration 48% at 1 microM alpha-LA compared with the control. The expression of glycogenin was increased (P < 0.05) 50% at 1 microM alpha-LA compared with the control. These results suggest that flaxseed supplementation to finishing steers for 28 d decreased gene expression of both LPL and glycogenin compared with not feeding flaxseed. Alterations in local concentrations of these two proteins could affect the ability of muscle to use fatty acids and glucose for energy, and, ultimately, affect carcass quality.