RESUMO
During the periparturient period, cows undergo heightened energy demands at lactation onset, paired with reduced dry matter intake, leading to negative energy balance (NEB). Excessive lipolysis-driven adipose tissue remodeling, triggered by NEB, significantly contributes to ketosis in periparturient dairy cows. However, the role of peripheral blood mononuclear cells (PBMCs) in the pathogenesis of ketosis and in modulating adipose tissue function remains poorly understood. Here, we investigated how ketosis affects the transcriptional profile and secretome of PBMCs and its influence on preadipocyte function in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). Twenty-one postpartum Holstein dairy cows were categorized as either subclinical ketosis (SCK; BHB ≥ 1.0 mM) or control (CON; BHB < 0.8 mM) based on blood beta-hydroxybutyrate (BHB) concentration screening. Blood samples were collected intravenously for the isolation of PBMCs and serum metabolic profiling. Ketosis elevated circulating NEFA and BHB levels but reduced total WBC and neutrophil counts. Isolated PBMCs were evaluated for gene expression and used to produce conditioned media (PBMC-CM), during which PBMCs were stimulated with 10 ng/mL LPS. The overall phenotype of PBMCs was largely consistent between SCK and CON cows, with minimal differences detected in immunomodulatory cytokine expression and PBMC-CM composition following stimulation. Preadipocytes isolated from non-ketotic cows were treated with PBMC-CM to assess the effect of PBMC secretomes on adipose cell function. Preadipocytes treated with SCK PBMC-CM showed reduced lipid accumulation compared to those treated with CON PBMC-CM regardless of the depot. SAT preadipocytes had heightened expression of lipid metabolism-related genes, including DGAT1, LIPE, and FASN, compared to VAT when treated with SCK PBMC-CM. Preadipocytes treated with CM from PBMC stimulated by LPS exhibited upregulation in IL1B and IL6 regardless of the depot or source of PBMCs. Together, these results indicate that although PBMC profiles showed minimal differences, preadipocytes treated with PBMC-CM may be influenced by additional factors, leading to altered preadipocyte function and gene expression that may contribute to adipose cellular dysfunction.
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Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to characterize the effects of beef or dairy maternal genetics and the dairy management system on calf growth. Pregnancies were created with a 2â ×â 2 factorial arrangement of dam breed (Holstein or Jersey) and mating type (artificial insemination or implantation of an in vitro produced embryo from a commercial beef cow oocyte). Resulting calves were reared in a calf ranch. Additionally, commercial beef cows were inseminated and reared resulting calves on range. Therefore, the five treatments were Angusâ ×â Holstein (Aâ ×â H; nâ =â 19), Angusâ ×â Jersey (Aâ ×â J; nâ =â 22), Angusâ ×â beef gestated by Holstein (H ET; nâ =â 18), Angusâ ×â beef gestated by Jersey (J ET; nâ =â 8), and Angusâ ×â beef raised by beef (Aâ ×â B; nâ =â 20). Beginning at birth, calf body weight, cannon circumference, forearm circumference, top width, hip width, and hip height were measured approximately every 28 d until ~196 d of age. At birth, Aâ ×â J calves weighed the least (Pâ <â 0.01). At 150 d of age, body weight was greatest (Pâ <â 0.05) among Aâ ×â B calves, intermediate among H ET and Aâ ×â H calves, and least among J ET and Aâ ×â J calves (Pâ <â 0.05). Morphometric differences were detected between treatments (multivariate analysis of variance, Pâ <â 0.01). Primary discriminant function scores identified Aâ ×â B calves having lesser values than Aâ ×â J or Aâ ×â H calves (analysis of variance [ANOVA], Pâ <â 0.01); Aâ ×â B calves had greater cannon circumference, greater top width, and less hip height (standardized loadings of -0.47, -0.48, and 0.63, respectively). Secondary discriminant function scores identified J ET and H ET to have greater forearm circumference-a key indicator of muscling-than Aâ ×â J or Aâ ×â H (ANOVA, Pâ <â 0.01; standardized loading of 0.99). The dairy management system limited growth rate of beef genetics compared to the beef management system. In addition, Holstein dams transmitted greater growth potential than Jersey dams. Replacing maternal dairy genetics with beef genetics moderated frame size and created a more muscular phenotype.
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Bovine leukemia virus (BLV) is a retrovirus of cattle that infects approximately 45% of all US dairy cattle, with about 90% of US dairy herds having at least one infected animal. Studies have found BLV infection to be associated with multiple measures of decreased immune function, which may explain the observed economic losses from milk production, decreased cow longevity, and predisposition to lymphoma and other diseases. Our objective was to measure the association between BLV infection and cow longevity in dairy cow operations. Ninety-one dairy herds from 9 US states volunteered to participate in this study. Milking dairy cows (n = 3,611) were tested for BLV antibodies using an ELISA milk test, and their presence in the herd was monitored for an average of 29 mo. The survival analysis controlled for herd and lactation number. Cows sold for dairy purposes were excluded, and individual cow results were not shared with producers so as not to influence culling decisions. Overall, 47.1% (1,701/3,611) of cows were BLV-positive by ELISA. The significant hazard ratio of 1.30 indicated that positive cows were 30% more likely than their negative herdmates to die or be culled during the monitoring period. These results are consistent with other studies in finding a negative effect of BLV infection on cow lifespan.
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Bovine leukemia virus (BLV) causes enzootic bovine leukosis, the most common neoplastic disease in cattle. Previous work estimates that 78% of US beef operations and 38% of US beef cattle are seropositive for BLV. Infection by BLV in a herd is an economic concern for producers as evidence suggests that it causes an increase in cost and a subsequent decrease in profit to producers. Studies investigating BLV in dairy cattle have noted disease resistance or susceptibility, measured by a proviral load (PVL) associated with specific alleles of the bovine leukocyte antigen (BoLA) DRB3 gene. This study aims to investigate the associations between BoLA DRB3 alleles and BLV PVL in beef cattle. Samples were collected from 157 Midwest beef cows. BoLA DRB3 alleles were identified and compared with BLV PVL. One BoLA DRB3 allele, *026:01, was found to be associated with high PVL in relation to the average of the sampled population. In contrast, two alleles, *033:01 and *002:01, were found to be associated with low PVL. This study provides evidence of a relationship between BoLA DRB3 alleles and BLV PVL in US beef cows.
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Bovine leukosis is a chronic lymphoproliferative disorder caused by bovine leukemia virus (BLV). Previous studies estimate that 38 % of cow-calf beef herds and 10.3 % of individual beef cows in the US are BLV seropositive. About 70 % of BLV infected animals are asymptomatic carriers of the virus, while less than 5% develop lymphosarcoma, the leading reason for carcass condemnation at the US slaughterhouses. Studies provide evidence that BLV infection leads to decreased immune function making animals more vulnerable to other diseases, which could shorten their productive lifespan and increase economic losses in the cattle industry. BLV seropositive dairy cows are reportedly more likely to be culled sooner compared with their uninfected herd mates. Beyond simple prevalence studies, little is known about the impact of BLV infection in beef cattle production or specifically on beef cow longevity. Our objective was to determine the association between BLV infection and cow longevity in beef cow-calf operations. Twenty-seven cow-calf herds from the Upper Midwest volunteered to participate in this study. Female beef cattle (n = 3146) were tested for serum BLV antibodies by ELISA. A subsample of 648 cows were also tested for BLV proviral load (PVL). Culling data was collected for the subsequent 24 months. Twenty-one herds (77.7 %) had at least one BLV-infected animal, and 29.2 % (930/3146) of tested animals were BLV seropositive. Of the BLV-positive cows, 33.7 % (318/943) were culled compared with 32.1 % (541/1682) of the seronegative cows. BLV status did not affect cows' longevity within herds (P = 0.062). However, cows with high BLV PVL had decreased survival within the herd compared with ELISA- negative cows (P = 0.01). Overall, infection with BLV did not impact beef cow longevity unless the disease had progressed to a point of high BLV PVL.
Assuntos
Leucose Enzoótica Bovina/fisiopatologia , Vírus da Leucemia Bovina/fisiologia , Longevidade , Animais , Bovinos , Leucose Enzoótica Bovina/virologia , FemininoRESUMO
Bovine leukosis is a chronic lymphoproliferative disorder that leads to significant economic losses in the beef and dairy industries. The major route of virus transmission is believed to be iatrogenic through the transfer of blood containing infected lymphocytes. In addition, BLV proviral DNA has been identified in nasal secretions, saliva, milk, colostrum, semen and smegma; however, natural transmission of BLV through these secretions has not been clearly demonstrated. The use of bulls for natural breeding has been identified as a risk factor in BLV infected dairy herds. However, the risk of BLV-infected bulls transmitting the virus is unknown. The objective of this study was to evaluate the potential for BLV transmission during natural breeding between a BLV-infected bull and uninfected heifers. Forty healthy, BLV seronegative, and proviral-negative beef heifers were randomly assigned to one of two groups: control heifers (nâ¯=â¯20) exposed to a BLV seronegative and proviral negative bull and challenged heifers (nâ¯=â¯20) exposed to a BLV seropositive and proviral-positive bull. Each group was housed with the bull for a period of 38 days in a 5-acre pasture to replicate the housing of commercial beef cattle during the breeding season. Blood samples were collected from heifers at -60, -30 and 0 days prior to breeding and day 30, 60 and 90 after the breeding period ended. Blood samples were tested for BLV antibodies by ELISA and BLV proviral DNA by CoCoMo-qPCR. New infection was not detected by ELISA or CoCoMo-qPCR in any of the challenge or control heifers at any time point during the study. Based on these results, BLV infected bulls that are healthy and aleukemic may not be a significant risk of BLV transmission during a defined breeding season.
Assuntos
Leucose Enzoótica Bovina/transmissão , Vírus da Leucemia Bovina/isolamento & purificação , Animais , Cruzamento/métodos , Bovinos , Leucose Enzoótica Bovina/epidemiologia , Feminino , Fatores de Risco , Esmegma/virologiaRESUMO
OBJECTIVE: To determine the prevalence of bovine leukemia virus (BLV) in beef bulls; evaluate the presence of BLV provirus DNA in blood, smegma, and semen samples; and analyze whether blood BLV proviral load was associated with differential blood cell counts. DESIGN: Observational cross-sectional study. ANIMALS: 121 beef bulls ≥ 2 years old from 39 Michigan herds. PROCEDURES: Blood, smegma, and semen samples were collected from each bull during a routine breeding soundness examination. An ELISA was used to detect serum anti-BLV antibodies. A coordination of common motifs-quantitative PCR assay was used to detect BLV provirus DNA in blood, smegma, and semen samples. Bulls with positive results on both the BLV serum ELISA and coordination of common motifs-quantitative PCR assay were considered infected with BLV. RESULTS: 19 of 39 (48.7%) herds and 54 of 121 (44.6%) bulls were infected with BLV. Provirus DNA was detected in the blood of all 54 and in smegma of 4 BLV-infected bulls but was not detected in any semen sample. Lymphocyte count was significantly greater in BLV-infected bulls than in uninfected bulls. The proportion of BLV-infected bulls with lymphocytosis (16/54 [29.6%]) was greater than the proportion of uninfected bulls with lymphocytosis (6/67 [9%]). Lymphocyte count was positively associated with BLV proviral load in BLV-infected bulls. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that almost half of beef bulls and herds were infected with BLV, and BLV provirus DNA was detected in the smegma of some BLV-infected bulls. Bulls may have an important role in BLV transmission in beef herds.
Assuntos
Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Animais , Cruzamento , Bovinos , Estudos Transversais , Leucose Enzoótica Bovina/transmissão , MasculinoRESUMO
Bovine leukemia virus (BLV) is a contagious, oncogenic deltaretrovirus of cattle with a worldwide distribution. In the US, over 40% of dairy cows are infected with the virus, and evidence of its economic impact is growing. This study evaluated the performance of a field-deployable automatic nucleic acid-extraction/insulated isothermal PCR (iiPCR) system for on-site BLV-proviral DNA detection in dairy cows compared with a conventional laboratory real-time PCR (rt-PCR). Assay performance was verified in parallel tests of 36 archived blood samples with 100% agreement (κâ¯=â¯1.0; nâ¯=â¯36) between the iiPCR and conventional rt-PCR systems, and the limit of detection of the iiPCR assay was estimated to be 4 copies (genome equivalent) per reaction. The field-deployable iiPCR system was subsequently used on-farm to test freshly collected blood samples, and showed 100% agreement (κâ¯=â¯1.0; nâ¯=â¯32) with the laboratory rt-PCR system. Fresh blood samples were collected on a second farm and tested on both systems, also with 100% agreement (κâ¯=â¯1.0; nâ¯=â¯34). The field-deployable iiPCR/POCKIT™ combo system performs as well as a conventional laboratory-based rt-PCR system for detection of BLV proviral DNA in whole blood and may be a useful tool for on-farm evaluation of BLV-infection status in dairy cattle.
Assuntos
DNA Viral/isolamento & purificação , Leucose Enzoótica Bovina/diagnóstico , Vírus da Leucemia Bovina/isolamento & purificação , Técnicas de Diagnóstico Molecular/métodos , Testes Imediatos , Reação em Cadeia da Polimerase/métodos , Provírus/isolamento & purificação , Animais , Automação/métodos , Bovinos , DNA Viral/genética , Leucose Enzoótica Bovina/virologia , Vírus da Leucemia Bovina/genética , Provírus/genéticaRESUMO
Bovine leukemia virus (BLV) is a retrovirus that is highly prevalent in US dairy herds: over 83% are BLV infected and the within-herd infection rate can be almost 50% on average. While BLV is known to cause lymphosarcomas, only 5% or fewer infected cattle will develop lymphoma; this low prevalence of cancer has historically not been a concern to dairy producers. However, more recent research has found that BLV+ cows without lymphoma produce less milk and have shorter lifespans than uninfected herdmates. It has been hypothesized that BLV infection interferes with normal immune function in infected cattle, and this could lead to reduced dairy production. To assess how naturally infected BLV+ cows responded to a primary and secondary immune challenge, 10 BLV+ and 10 BLV- cows were injected subcutaneously with keyhole limpet hemocyanin (KLH) and dimethyldioctadecylammonium bromide. B- and T-cell responses were characterized over the following 28 days. A total of 56 days after primary KLH exposure, cows were re-injected with KLH and B- and T-cell responses were characterized again over the following 28 days. BLV+ cows produced less KLH-specific IgM after primary immune stimulation; demonstrated fewer CD45R0+ B cells, altered proportions of CD5+ B cells, altered expression of CD5 on CD5+ B cells, and reduced MHCII surface expression on B cells ex vivo; exhibited reduced B-cell activation in vitro; and displayed an increase in BLV proviral load after KLH exposure. In addition, BLV+ cows had a reduced CD45R0+γδ+ T-cell population in the periphery and demonstrated a greater prevalence of IL4-producing T cells in vitro. All together, our results demonstrate that both B- and T-cell immunities are disrupted in BLV+ cows and that antigen-specific deficiencies can be detected in BLV+ cows even after a primary immune exposure.