Susceptible Cows Research Articles

Potential biomarkers for lameness and claw lesions in dairy cows: A scoping review.

One of the major challenges in lameness management is prompt detection, especially before visible gait disturbance. This scoping review describes the potential biomarkers for lameness in dairy cows reported in the literature, their relevance in lameness diagnosis, identifying cows at risk of developing claw lesions and monitoring recovery after treatment. Using specific keywords, a comprehensive literature search was performed in three databases: PubMed, Google Scholar and ScienceDirect to retrieve relevant articles published between 2010 and 2022. A total of 31 articles fulfilling the inclusion criteria were analysed. The categories of potential markers for lameness reported in the literature included acute phase proteins (APPs), nociceptive neuropeptides, stress hormones, proteomes, inflammatory cytokines and metabolites in serum, urine and milk. Cortisol, APPs (serum amyloid A and haptoglobin) and serum, urinary and milk metabolites were the most studied biomarkers for lameness in dairy cows. While APPs, nociceptive neuropeptides and blood cortisol analyses assisted in elucidating the pain and stress experienced by lame cows during diagnosis and after treatment, evidence-based data are lacking to support their use in identifying susceptible animals. Meanwhile, metabolomic techniques revealed promising results in assessing metabolic alterations occurring before, during and after lameness onset. Several metabolites in serum, urinary and milk were reported that could be used to identify susceptible cows even before the onset of clinical signs. Nevertheless, further research is required employing metabolomic techniques to advance our knowledge of claw horn lesions and the discovery of novel biomarkers for identifying susceptible cows. The applicability of these biomarkers is challenging, particularly in the field, as they often require invasive procedures.

Early detection and effective treatment of milk fever in high-yield dairy cows

Production diseases arise from management practices, leading to metabolic imbalances in high-yielding dairy cows. Milk fever, or parturient paresis, is a significant production ailment occurring during the periparturient phase. The heightened milk production during this period places an increased demand on calcium, often resulting in milk fever (hypocalcemia) characterized by abnormally low blood calcium levels. Clinical manifestations of milk fever include reduced appetite, tetanus, low body temperature, paresis, lateral recumbency, and, if untreated, progression to coma and death. Although sporadic, the incidence of milk fever can be high among susceptible cows on individual farms, particularly those with high milk production. Various factors contribute to increased milk fever incidence, including parturition, lactation initiation, advanced age, breed, and diet. Intravenous treatment with calcium borogluconate is the standard approach for parturient paresis. Early and proper treatment results in an excellent prognosis for affected cows. Economic losses due to milk fever encompass deaths, premature culling, treatment expenses, and reduced milk production in subsequent lactations. Consequently, effective milk fever management is crucial not only for mitigating production losses but also for preserving the well-being of the animals.

Susceptibility of dairy cows to subacute ruminal acidosis is reflected in both prepartum and postpartum bacteria as well as odd- and branched-chain fatty acids in feces

BackgroundThe transition period is a challenging period for high-producing dairy cattle. Cows in early lactation are considered as a group at risk of subacute ruminal acidosis (SARA). Variability in SARA susceptibility in early lactation is hypothesized to be reflected in fecal characteristics such as fecal pH, dry matter content, volatile and odd- and branched-chain fatty acids (VFA and OBCFA, respectively), as well as fecal microbiota. This was investigated with 38 periparturient dairy cows, which were classified into four groups differing in median and mean time of reticular pH below 6 as well as area under the curve of pH below 6. Furthermore, we investigated whether fecal differences were already obvious during a period prior to the SARA risk (prepartum).ResultsVariation in reticular pH during a 3-week postpartum period was not associated with differences in fecal pH and VFA concentration. In the postpartum period, the copy number of fecal bacteria and methanogens of unsusceptible (UN) cows was higher than moderately susceptible (MS) or susceptible (SU) cows, while the genera Ruminococcus and Prevotellacea_UCG-001 were proportionally less abundant in UN compared with SU cows. Nevertheless, only a minor reduction was observed in iso-BCFA proportions in fecal fatty acids of SU cows, particularly iso-C15:0 and iso-C16:0, compared with UN cows. Consistent with the bacterial changes postpartum, the lower abundance of Ruminococcus was already observed in the prepartum fecal bacterial communities of UN cows, whereas Lachnospiraceae_UCG-001 was increased. Nevertheless, no differences were observed in the prepartum fecal VFA or OBCFA profiles among the groups. Prepartum fecal bacterial communities of cows were clustered into two distinct clusters with 70% of the SU cows belonging to cluster 1, in which they represented 60% of the animals.ConclusionsInter-animal variation in postpartum SARA susceptibility was reflected in post- and prepartum fecal bacterial communities. Differences in prepartum fecal bacterial communities could alert for susceptibility to develop SARA postpartum. Our results generated knowledge on the association between fecal bacteria and SARA development which could be further explored in a prevention strategy.Graphical abstract

In Silico Tools for Analysis of Single-Nucleotide Polymorphisms in the Bovine Transferrin Gene.

Simple SummarySubclinical mastitis represents a significant disease in dairy animals and negatively impacts udder health. Genetics, pathogens, and poor health and management procedures in dairy animals contribute primarily to this disease. Animal genetics plays a major role in disease resistance and susceptibility. Studying single-nucleotide polymorphisms in genes helps to detect resistant and susceptible animals. Transferrin is one of the important glycoproteins involved in the innate immune system that prevents iron availability to pathogens. Several studies have reported polymorphism in the transferrin gene in dairy animals with mastitis, but no detailed information on in silico tools is available for identification and verification. So, this study was carried out to detect polymorphism in the transferrin gene in healthy and mastitic cows, and to use various in silico based tools and software to find the impact of single-nucleotide polymorphisms (SNPs) on animal health. The results indicated three SNPs were located in the transferrin gene of Holstein Friesian cross-bred dairy cows. Moreover, the use of online computational tools provided significant knowledge regarding whether the SNPs would be deleterious, damaging, benign, neutral, or affect protein stability and function.Dairy cattle with a high milk yield are susceptible to many infectious diseases, such as mastitis. Subclinical mastitis (SCM) is the most prevalent form of mastitis that predominantly affects animal health, and causes adverse effects on the quality and quantity of milk. In dairy animals, subclinical mastitis often remains undetected, as no gross changes in udder characteristics are visible. In the present study, 135 Holstein Friesian dairy animals were selected and screened as healthy (n = 25) and mastitic (n = 110) based on diagnostic tests such as the California mastitis test, pH, electrical conductivity, and somatic cell count. In this study, the somatic cell count was used as a gold-standard test in differentiating subclinical mastitis animals from healthy ones. The present study was carried out to study polymorphisms in the bovine transferrin gene in cows (with subclinical mastitis and healthy). For the early detection of resistant/or susceptible animals, a useful marker could be provided by the detection of single-nucleotide polymorphisms (SNPs) in the transferrin gene, which are often associated with mammary innate immune response. The sequencing results revealed three nucleotide substitutions: two transversions (230 A > C, 231 C > A) and one transition (294 A > G) in susceptible cows as compared to disease-free subjects. The nucleotide variations at position 230 (GAC > GCA) and 231 (GAC > GCA) were nonsynonymous, and corresponded to an amino acid change from aspartic acid to alanine; whereas at position 294 (GAA > GAG), the mutation was synonymous. In the present study, many in silico tools were taken into consideration to determine the effect of SNPs on protein structure and function. The PROVEAN tool found the amino acid substitution to be neutral and deleterious. PolyPhen-2 revealed the amino acid variations at positions 320 and 321 to most likely be damaging; and at the 341 position, the variations were benign. The I-Mutant and MUpro tools found that the protein stability decreased for nonsynonymous variations. The SIFT tool revealed the protein function was likely to be affected in nonsynonymous variations, with no change in the case of synonymous ones. Phylogenetic analysis of the bovine transferrin gene revealed a close relation of the CA allele with the Bos taurus transferrin, while the G allele was closely related to a cross of Bos indicus × Bos taurus serotransferrins, followed by the Bison bison transferrin. The least relation was shown by both alleles to Capra hircus, Ovis aries, and Bubalus bubalis.

Identification of Serum-Predictive Biomarkers for Subclinical Mastitis in Dairy Cows and New Insights into the Pathobiology of the Disease.

Targeted direct injection/liquid chromatography coupled to tandem mass spectrometry-based metabolomics was employed to identify metabolite alterations that could differentiate subclinical mastitis (SCM) from control (CON) dairy cows at -8, -4, disease diagnosis, +4 and +8 wks relative to parturition. We identified and measured 128 metabolites in the serum. Univariate analysis revealed significant alterations of serum metabolites at all five time points studied. By applying multivariate analyses including principle component analysis and partial least squares-discriminant analysis, some of the metabolites were found to have the strongest power for discriminating the SCM from CON cows. The top five metabolites with the greatest variable importance in projection values were selected as potential biomarkers for SCM. A set of five serum metabolites including lysine, ornithine, isoleucine, LysoPC a C17:0, and leucine at -8 wks and five other metabolites including lysine, leucine, isoleucine, kynurenine, and sphingomyelin (SM) C26:0 at -4 wks prepartum were determined as predictive biomarkers for SCM, which provided highly predictive capabilities with AUC (area under the curve) at 1.00. Five metabolites including lysine, leucine, isoleucine, kynurenine, and SM C26:1 in the serum were identified as diagnostic biomarkers for SCM with the AUC of 1.00. Moreover, we observed that distinct metabolic pathways were affected in SCM cows including lysine degradation, biotin, cysteine, methionine, and glutathione metabolism, valine, leucine, and isoleucine biosynthesis and degradation, and aminoacyl-tRNA biosynthesis prior to and during the occurrence of the disease. Results of this study showed that metabolomics analyses can be used to identify susceptible cows to SCM starting from -8 and -4 wks prepartum and that blood can be used to diagnose cows with SCM.

Blood Metabolomic Phenotyping of Dry Cows Could Predict the High Milk Somatic Cells in Early Lactation—Preliminary Results

Subclinical mastitis (SCM) is a very common disease of dairy cows. Currently, somatic cell count (SCC) is used for SCM diagnoses. There are no prognostic tests to detect which cows may develop SCM during the dry-off period. Therefore, the objectives of this study were to identify metabolic alterations in the serum of pre-SCM cows during the dry-off period, at −8 and −4 weeks before calving, through a targeted mass spectrometry (MS) assay. Fifteen cows, free of any disease, and 10 cows affected only by SCM postpartum served as controls (CON) and the SCM group, respectively. Results showed 59 and 47 metabolites that differentiated (p ≤ 0.05) CON and pre-SCM cows at –8 and −4 weeks prior to the expected date of parturition, respectively. Regression analysis indicated that a panel of four serum metabolites (AUC = 0.92, p < 0.001) at −8 weeks and another four metabolites (AUC = 0.92, p < 0.01) at −4 weeks prior to parturition might serve as predictive biomarkers for SCM. Early identification of susceptible cows can enable development of better preventive measurements ahead of disease occurrence.

Responsive changes of rumen microbiome and metabolome in dairy cows with different susceptibility to subacute ruminal acidosis.

Subacute ruminal acidosis (SARA) represents one of the most important digestive disorders in intensive dairy farms, and dairy cows are individually different in the severity of SARA risk. The objectives of the current study were to investigate differences in the ruminal bacterial community and metabolome in dairy cattle with different susceptibility to SARA. In the present study, 12 cows were initially enrolled in the experiment. Based on average ruminal pH, 4 cows with the lowest ruminal pH were assigned to the susceptible group (SUS, pH = 5.76, n = 4) and 4 cows with the highest ruminal pH assigned to the tolerant group (TOL, pH = 6.10, n = 4). Rumen contents from susceptible (SUS, n = 4) and tolerant (TOL, n = 4) dairy cows were collected through rumen fistula to systematically reveal the rumen microbial and metabolic alterations of dairy cows with different susceptibility to SARA using multi-omics approaches (16S and 18S rRNA gene sequencing and metabolome). The results showed that despite being fed the same diet, SUS cows had lower ruminal pH and higher concentrations of total volatile fatty acids (VFA) and propionate than TOL cows (P < 0.05). No significant differences were observed in dry matter intake, milk yield, and other milk compositions between the SUS and TOL groups (P > 0.05). The principal coordinates analysis based on the analysis of molecular variance indicated a significant difference in bacterial composition between the two groups (P = 0.01). More specifically, the relative abundance of starch-degrading bacteria (Prevotella spp.) was greater (P < 0.05), while the proportion of fiber-degrading bacteria (unclassified Ruminococcaceae spp., Ruminococcus spp., Papillibacter, and unclassified Family_XIII) was lower in the rumen of SUS cows compared with TOL cows (P < 0.05). Community analysis of protozoa showed that there were no significant differences in the diversity, richness, and community structure (P > 0.05). Metabolomics analysis revealed that the concentrations of organic acids (such as lactic acid), biogenic amines (such as histamine), and bacterial degradation products (such as hypoxanthine) were significantly higher in the SUS group compared to the TOL group (P < 0.05). These findings revealed that the higher proportion of starch-degrading bacteria/lower fiber-degrading bacteria in the rumen of SUS cows resulted in higher VFA-producing capacity, in particular propionate. This caused a disruption in metabolic homeostasis in the rumen which might be the reason for the higher susceptibility to SARA. Overall, these findings enhanced our understanding of the ruminal microbiome and metabolic changes in cows susceptible to SARA.

​Discriminant Analysis to Characterize Mastitis Resistant and Susceptible Karan Fries Cows and Response Operating Characteristics Curve for Comparing Regression/ Discriminant Model

Background: The profitability in the dairy enterprises is strongly affected by udder health and, to a minor extent, by morphometry. The present study was conducted to differentiate mastitis susceptible and resistant animals based on udder and teat type traits infrequently exist. Methods: The study was undertaken in ICAR-NDRI, Karnal of Haryana. A discriminate model was applied to differentiate mastitis susceptible and resistant Karan Fries cows for the study. For meeting the objective; 123 Karan Fries cows were subjected to developing a reliable mathematical function/equation (discriminant functions) for the provision of maximum separation among the mastitis resistant and susceptible animals. The hypothesis was designed to know if these udder and type traits appeal to mastitis-resistant and susceptible animals. The hypothesis for testing the equality of covariance matrices was depicted as: H0: ∑1 = ∑2 Vrs H1: At least one pair of sigma’s ∑ is different. Result: The model included contributory factors such as fore udder length, central ligament, udder balance, shortest distance of floor from fore teat (SDFT), shortest distance of floor from rear teat (SDRT), fore udder attachment (FUA), teat direction, Rear legs rearview, Hock development, udder depth, and udder width constructed and was found to demonstrate 69.1 per cent accuracy with p less than 0.001 and the Karan Fries functions at group centroids are -0.169 and 0.443 respectively for mastitis resistant and mastitis infected animals. The model will facilitate 92.1 per cent of the cases to correctly classify for mastitis resistant animals and the remaining 7.9 per cent being misclassified into the mastitis group.

Novel Facets of the Liver Transcriptome Are Associated with the Susceptibility and Resistance to Lipid-Related Metabolic Disorders in Periparturient Holstein Cows.

Simple SummaryEnergy and nutrient demands of the early lactation period can result in the development of metabolic disorders, such as ketosis and fatty liver, in dairy cows. Variability in the incidence of these disorders suggests that some cows have an ability to adapt. The objective of this study was to discover differences in liver gene expression that are associated with a cow’s susceptibility (disposition to disorder during typical conditions) or resistance (disposition to disorder onset and severity when presented a challenge) to metabolic disorders. Cows in a control treatment and a ketosis induction protocol treatment were retrospectively grouped into susceptibility and resistance groups, respectively, by a machine learning algorithm using lipid biomarker concentrations. Whole-transcriptome RNA sequencing was performed on liver samples from these cows. More susceptible cows had lower expression of glutathione metabolism genes, while less resistant cows had greater expression of eicosanoid-metabolism-related genes. Additionally, differentially expressed genes suggested a role for immune-response-related genes in conferring susceptibility and resistance to metabolic disorders. The overall inferred metabolism suggests that responses to oxidative stress may determine susceptibility and resistance to metabolic disorders, with novel implications for immunometabolism.Lipid-related metabolic disorders (LRMD) are prevalent in early lactation dairy cows, and have detrimental effects on productivity and health. Our objectives were to identify cows resistant or susceptible to LRMD using a ketosis induction protocol (KIP) to discover differentially expressed liver genes and metabolic pathways associated with disposition. Clustering cows based on postpartum lipid metabolite concentrations within dietary treatments identified cows more or less susceptible (MS vs. LS) to LRMD within the control treatment, and more or less resistant (MR vs. LR) within the KIP treatment. Whole-transcriptome RNA sequencing was performed on liver samples (−28, +1, and +14 days relative to calving) to assess differential gene and pathway expression (LS vs. MS; MR vs. LR; n = 3 cows per cluster). Cows within the MS and LR clusters had evidence of greater blood serum β-hydroxybutyrate concentration and liver triglyceride content than the LS and MR clusters, respectively. The inferred metabolism of differentially expressed genes suggested a role of immune response (i.e., interferon-inducible proteins and major histocompatibility complex molecules). Additionally, unique roles for glutathione metabolism and eicosanoid metabolism in modulating susceptibility and resistance, respectively, were implicated. Overall, this research provides novel insight into the role of immunometabolism in LRMD pathology, and suggests the potential for unique control points for LRMD progression and severity.

A Multi-Platform Metabolomics Approach Identifies Urinary Metabolite Signatures That Differentiate Ketotic From Healthy Dairy Cows.

Ketosis and subclinical ketosis are widespread among dairy cows especially after calving. Etiopathology of ketosis has been related to negative energy balance. The objective of this study was to investigate metabolite fingerprints in the urine of pre-ketotic, ketotic, and post-ketotic cows to identify potential metabolite alterations that can be used in the future to identify susceptible cows for ketosis and metabolic pathways involved in the development of disease. In this study, NMR, DI/LC-MS/MS, and GC-MS-based metabolomics were used to analyze urine samples from 6 cows diagnosed with ketosis and 20 healthy control (CON) cows at −8 and −4 weeks prepartum, the week (+1 to +3) of ketosis diagnosis, and at +4 and +8 weeks after parturition. Univariate and multivariate analyses were used to screen metabolite panels that can identify cows at their pre-ketotic stage. A total of 54, 42, 48, 16, and 31 differential metabolites between the ketotic and CON cows were identified at −8 and −4 weeks prepartum, ketosis week, and at +4, and +8 weeks postpartum, respectively. Variable importance in projection (VIP) plots ranked the most significant differential metabolites, which differentiated ketotic cows from the CON ones. Additionally, several metabolic pathways that are related to ketosis were identified. Moreover, two promising metabolite panels were identified which clearly separated ketotic from CON cows with excellent level of sensitivity and specificity. Overall, multiple urinary metabolite alterations were identified in pre-ketotic, ketotic, and post-ketotic cows. The metabolite panels identified need to be validated in the future in a larger cohort of animals.

Evaluation of Alterations in Uterine Blood Flow using Doppler Ultrasonography in Pregnant, Genotyped Beef Cows and Heifers Consuming Endophyte-Infected Tall Fescue Seeds and Supplemented with Rumen-Protected Niacin

Fescue toxicity is a nutritional-related disease generated in a forage-based beef herd exposed to ergot alkaloids (i.e. ergovaline) present in endophyte-infected tall fescue that produces important economic losses. The combination of a genetic test for susceptibility to fescue toxicity and supplementation with rumen-protected niacin could potentially reduce the toxic effects of ergovaline on beef cow and heifers’ reproductive performance during mid-gestation by improving uterine blood flow. Our main objective was to use color Doppler ultrasonography to evaluate the occurrence of any alteration in uterine arterial blood flow in pregnant, genotyped beef cows and heifers exposed to endophyte-infected tall fescue seeds and supplemented with rumen-protected niacin. We hypothesize that genetically-tested susceptible control beef cows will have narrower uterine arteries and decrease blood flow as compared to tolerant cows that received rumen-protected niacin. Rumen-protected niacin was selected for this study due to its well-known effect as a vasodilator. Therefore, it might help cope with blood vessel constriction generated by ergovaline present in endophyte-infected tall fescue seeds. Results showed the negative effect of exposure to ergovaline in the uterine blood flow of pregnant beef cattle through an increase in the resistivity index. No Doppler parameters detected positive effects of genetic and nutritional treatments.

Assessment of candidate biomarkers to detect resistance to Mycobacterium bovis in Holstein-Friesian cattle

Bovine tuberculosis (bTB) caused by Mycobacterium bovis has a significant economic impact worldwide each year. Control of bTB is based on skin testing and removal of reactors. However, additional strategies are required to control this disorder. Natural disease resistance has been defined as the inherent capacity of an individual to resist disease when exposed to pathogens without previous exposure or immunization. However, little is known about natural disease resistance against Mycobacterium bovis in cattle. In this study, we aimed to identify candidate biomarkers to detect host resistance to M. bovis. We used a microbicidal assay to identify the resistance phenotype. A genomic microarray analysis was carried out on RNA from 2 resistant (R) and 2 susceptible (S) cows. Our results evidenced 69 differentially expressed genes. A subset of six genes that showed differential up (IL1RN), and down-regulation (VNN, GATM, ARHGEF11, NAAA and HSPA2) were selected for further analysis. To further validate the candidate biomarkers, we identified the R phenotype in 31 cattle (9 R and 22 S). Macrophage mRNA was isolated from this group of cattle. Expression of candidate biomarkers was evaluated by qPCR 2-ΔCt and ROC curves to determine their diagnostic potential. Candidates IL1RN and ARHGEF11 discriminates between R and S cattle. Furthermore, combination of candidates ARHGEF11: VNN: HSPA2 discriminate between R from S with AUC 0.7993 and agreement index of 0.853 (p ≤ 0.01). Our data suggest that candidate biomarkers may support the preliminary screening to identify natural resistance in herds against Mycobacterium bovis in Holstein-Friesian cattle.

Association of BoLA-DRB3.2 alleles with fusobacteriosis in cows

The Major Histocompatability Complex (MHC) determines the immune response to pathogens, and its genes are promising candidates for the search of associations with diseases. A special role is played by BoLA-DRB3 gene, the product of which directly participates in the binding of alien antigens and conditions the specificity of the immune response. The second exon of this gene codes β1-domain of class II antigens, which is necessary for binding a broad spectrum of alien antigens. Exon 2 of BoLA-DRB3 gene is extremely polymorphic, giving the possibility to search the associations of its alleles with various diseases. The article provides the results of the study on polymorphism of alleles of BoLA-DRB3.2 gene for detection of its associations with sensitivity to fusobacteriosis (necrobacteriosis) of cows. The survey was performed using PCR-RFLP method with DNA of blood from 176 cows of two herds of Ukrainian black-and-white dairy breed. As a result of the studies, in the first herd, 25 BoLA-DRB3.2 alleles were found. In the selections of nectobacteriosis susceptible and resistant cows, we found 22 and 21 variants respectively. In the second herd, in the general selection and group of healthy animals, 27 alleles were typed, and 22 in the group of susceptible cows. BoLA-DRB3.2*22 allele was the commonest in both herds in both general selections and groups of nectobacteriosis-resistant cows. In the selection of susceptible animals, the commonest was the variant BoLA-DRB3.2*16. We determined statistically significant associations of BoLA-DRB3.2 alleles with sensitivity to nectobacteriosis of cattle. BoLA-DRB3.2*03 and *22 alleles associate with nectobacteriosis-resistant, while *16 and *23 – with nectobacteriosis-susceptible cows of the both studied groups. Also, in the first herd, another allele was found – *24, indicating close relationship with the disease. The studies of polymorphism of BoLA-DRB3 gene expand the knowledge about genetic peculiarities of the Ukrainian black-and-white dairy breed. The identified molecular-genetic markers could be useful for breeders whose work is oriented towards the formation of herds which are resistant to diseases of the limbs in cattle.

Assessing selection signatures within and between selected lines of dual-purpose black and white and German Holstein cattle.

The aim of this study was to detect selection signatures considering cows from the German Holstein (GH) and the local dual-purpose black and white (DSN) population, as well as from generated sub-populations. The 4654 GH and 261 DSN cows were genotyped with the BovineSNP50 Genotyping BeadChip. The geographical herd location was used as an environmental descriptor to create the East-DSN and West-DSN sub-populations. In addition, two further sub-populations of GH cows were generated, using the extreme values for solutions of residual effects of cows for the claw disorder dermatitis digitalis. These groups represented the most susceptible and most resistant cows. We used cross-population extended haplotype homozygosity methodology (XP-EHH) to identify the most recent selection signatures. Furthermore, we calculated Wright's fixation index (FST ). Chromosomal segments for the top 0.1 percentile of negative or positive XP-EHH scores were studied in detail. For gene annotations, we used the Ensembl database and we considered a window of 250kbp downstream and upstream of each core SNP corresponding to peaks of XP-EHH. In addition, functional interactions among potential candidate genes were inferred via gene network analyses. The most outstanding XP-EHH score was on chromosome 12 (at 77.34Mb) for DSN and on chromosome 20 (at 36.29-38.42Mb) for GH. Selection signature locations harbored QTL for several economically important milk and meat quality traits, reflecting the different breeding goals for GH and DSN. The average FST value between GH and DSN was quite low (0.068), indicating shared founders. For group stratifications according to cow health, several identified potential candidate genes influence disease resistance, especially to dermatitis digitalis.

Serum metabolic fingerprinting of pre-lameness dairy cows by GC–MS reveals typical profiles that can identify susceptible cows

The objectives of this study were to identify metabolite fingerprints in the serum related to amino acid (AA), carbohydrate, and lipid metabolism in transition dairy cows at −8 and −4 wks prior to parturition, at +2 wks postpartum during lameness diagnosis as well as at +4 and +8 wks after parturition. All cases of lameness occurred at around +2 wks after parturition. Out of 100 dairy cows included in this nested case-control study only 6 pregnant multiparous (parity: 3.0 ± 0.6, Mean ± SEM) Holstein dairy cows with lameness only and 20 healthy control cows (CON) were selected for serum GC–MS metabolomics analysis. All cows selected were not injured mechanically and had similar parity (3.3 ± 0.6) and body condition score (BCS). A total of 29 metabolites were identified and quantified in the serum. Results showed that 18 and 15 metabolites differentiated pre-lame cows from CON ones at −8 and −4 wks prior to parturition. Ten metabolites were found altered at the week of lameness diagnosis. Of note: pre-lame cows were characterized by greater concentrations of several amino acids including Gly, Leu, Phe, Ser, Val, D-mannose, Myo-inositol, and phosphoric acid (PA) at −8 and −4 wks prior to lameness and at the week of lameness diagnosis. At +4 wks after parturition 11 metabolites were altered in lameness cows, and at +8 wks there were 13 metabolites that differentiated the two groups. The high accuracy of the top 6 metabolites at −8 wks prior to parturition or approximately 9–11 wks before lameness diagnosis (Glu, Orn, Phe, Ser, Val, and PA) and another 5 metabolites at −4 wks before parturition, or approximately 5–7 wks before lameness diagnosis (Leu, Orn, Phe, Ser, and D-mannose) suggest that those metabolites may serve as potential monitoring biomarkers of lameness prior to lameness diagnosis. Data also showed multiple alterations during the week of lameness as well as at +4 and +8 wks postpartum suggesting lame cows are not metabolically healthy several weeks after the incidence of lameness. SignificanceLameness is one of the top three health issues of dairy cows in Canada that influences early culling of dairy cows. Despite a few efforts, there is scarcity of data regarding metabolic alterations that precede, associate, and follow lameness. We investigated whether alterations in the metabolite signatures prior, during, and after development of lameness can be used to screen cows for susceptibility to lameness, characterize lameness from the metabolic prospective, and predict the outcome of this economically important health issue of dairy cows. The results demonstrate typical metabotypes as shown by increased serum concentrations of Val, Gly, Ser, Leu, Phe, D-mannose, myo-inositol, and phosphoric acid at −8 and −4 wks prior to parturition (or −6 to −10 wks prior to occurrence of lameness) and at the week of lameness diagnosis.

Dynamics of somatic cell count patterns as a proxy for transmission of mastitis pathogens

Management of udder health is particularly focused on preventing new infections. Data from the DeLaval Online Cell Counter (DeLaval, Tumba, Sweden) may be used in forecasting to improve decision support for improved udder health management. It provides online cell counts (OCC) as a proxy for somatic cell counts from every milking at the cow level. However, these values are typically too insensitive and nonspecific to indicate subclinical intramammary infection (IMI). Our aim was to describe and evaluate use of dynamic transmission models to forecast subclinical IMI episodes using milk cultures or changes in OCC patterns over time. The latter was expressed by an elevated mastitis risk variable. Data were obtained from the dairy herd of the Norwegian University of Life Sciences (Oslo, Norway). In total, 173 cows were sampled monthly for bacteriological milk culture during a 17-mo study period and 5,330 quarter milk samples were cultured. Mastitis pathogens identified were assigned to 1 of 2 groups, Pat 1 or Pat 2. Pathogens from which a high cell count would be expected during a subclinical IMI episode were assigned to the Pat 1 group. Pathogens not in the Pat 1 group were assigned to the Pat 2 group. Staphylococcus epidermidis, Staphylococcus aureus, and Streptococcus dysgalactiae were the most common Pat 1 pathogens. Corynebacterium bovis, Staphylococcus chromogenes, and Staphylococcus haemolyticus were the most common Pat 2 pathogens. The OCC were successfully recorded from 82,182 of 96,542 milkings. The current study included 324 subclinical IMI episodes. None of the mastitis pathogens demonstrated a basic reproduction number (R0) >1. Patterns of OCC change related to an episode of Pat 1 subclinical IMI at specificity levels of 80, 90, and 95% at sensitivity levels of 69, 59, and 48% respectively, demonstrated an R0 >1. An existing infection was significant for transmission for several Pat 2 pathogens, but only for Staphylococcus aureus and Staphylococcus epidermidis among Pat 1 pathogens. Dynamic transmission models showed that patterns of OCC change related to an episode of Pat 1 subclinical IMI were significantly related to the same pattern occurring in susceptible cows at specificity levels of 80, 90, and 99% at sensitivity levels of 69, 48, and 8%, respectively. We conclude that changes in herd prevalence of subclinical IMI can be predicted using dynamic transmission models based on patterns of OCC change. Choice of specificity level depends on management goals and tolerance for false-positive alerts.

155 Evaluation of cytokine response as an indicator of genetic resistance to fescue toxicosis in purebred Angus cattle

Abstract Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue. However, varying responses among cattle potentially implies genetic tolerance to the syndrome. Therefore, the objective was to evaluate the cytokine response of cows deemed either tolerant or susceptible to endophyte-infected fescue. Angus cows, 2–4 yrs old, grazed endophyte-infected tall fescue at two locations for 13 weeks starting mid-April 2016. A post-hoc analysis of animal performance was utilized to designate cattle into either tolerant (n = 20) or susceptible (n = 20) groups, based on physiological responses (changes in ADG) to chronic exposure to endophyte-infected fescue. Blood samples collected on weeks 1, 7, and 13 were used to evaluate serum prolactin (PRL) concentration. Cytokine concentrations were evaluated via Quantibody Bovine Cytokine Arrays. Data were analyzed using PROC MIXED of SAS with repeated measures. There were no differences by location or week. Tolerant cows tended to have decreased overall PRL concentrations compared to susceptible cows (98.3 and 138.4 ng/mL, respectively; P = 0.08). G protein-coupled receptor associated sorting protein (GASP)-1, a down-regulator of G protein-coupled receptors including D2-dopamine receptor a regulator of PRL secretion, was greater in tolerant cows when compared to susceptible cows (4.7 and 4.2 ng/mL; P = 0.03). Vascular endothelial growth factor (VEGF)-A was greater in tolerant cows when compared to susceptible cows (0.5 and 0.2 ng/mL; P = 0.02). Finally, interleukin (IL)-4, an anti-inflammatory cytokine, tended to be greater in tolerant cows when compared to susceptible cows (2.2 and 0.8 ng/mL, respectively; P = 0.07). Based on these data, greater concentrations of GASP-1, VEGF-A, and IL-4 in tolerant compared to susceptible cattle may mitigate the detrimental effects of fescue toxicosis, including suppressed PRL and vasoconstriction, leading to improved animal performance in a fescue environment. Additionally, these cytokines may serve as potential biomarkers for determining an animal’s tolerance or susceptibility to negative effects associated with endophyte-infected tall fescue

Identification of Sindhi cows that are susceptible or resistant to Haematobia irritans.

To identify susceptible and resistant Haematobia irritans cows, horn flies were counted biweekly for 3 years in a herd of 25 Sindhi cows. Repeated measures linear mixed models were created including cow as a random factor. The results were analyzed by: 1) observing horn fly counts, considering fly-susceptible cows with infestations appearing in the upper quartile more than 50% of the weeks and in the lower quartile less than 20% of the weeks, and fly-resistant cows those that the number of flies was in the lower quartile more than 50% of the weeks and in the upper quartile less than 20%; 2) by the best linear unbiased predictions (BLUPs), to evaluate the cow effect on fly counts. Fly-susceptible cows were those in which the infestation appeared in the 90th percentile of the BLUPs, whereas fly-resistant cows appeared in the 10th percentile. For the observational method the individuals identified as resistant varied between 8% and 20% and 8% to 12% were susceptible. For the BLUP method, the rates of susceptible and resistant cows were 12%. The agreement among methods suggests that susceptible cows can be identified by observations of fly counts, allowing for selective breeding, culling or treatment.

Distinct blood and milk 18-carbon fatty acid proportions and buccal bacterial populations in dairy cows differing in reticulorumen pH response to dietary supplementation of rapidly fermentable carbohydrates

Nine Holstein dairy cows were fed diets with increasing proportions of rapidly fermentable carbohydrates (RFCH) to investigate the effect on reticular pH, milk fat content (MFC), 18-carbon fatty acid proportions in blood plasma and milk, and bacterial community in buccal swab samples. Inter-animal variation was expected in terms of reticular pH response upon higher RFCH proportions, which would be reflected in the occurrence or not of milk fat depression (MFD). Moreover, this variation in occurrence of MFD was hypothesized to be related to differences in blood and milk fatty acid proportions and in the bacterial community in buccal samples. Cows were fed a total mixed ration throughout the experiment, which consisted of 4 periods: adaptation (d 0-4) and low (d 5-18), increasing (d 19-24), and high RFCH (d 25-28). During the increasing RFCH period, the standard concentrate (211 g of starch/kg of dry matter) was gradually and partly replaced by a concentrate high in RFCH (486 g of starch/kg of dry matter). The reticular pH was measured using a bolus and the time below pH 6.00 was calculated on a daily basis. On d 13, 14, 25, 27, and 28, plasma and milk samples were collected and analyzed for 18-carbon fatty acid proportions, and buccal swabs were collected for bacterial community analysis based on 16S rRNA gene amplicon sequencing. Inter-animal variation was observed in terms of reticular pH, which allowed us to divide the cows into 2 groups: tolerant (time below pH 6.00 ≤ 0.1 h/d) and susceptible cows (time below pH 6.00 ≥ 1.26 h/d). The lower reticular pH of susceptible cows was accompanied by lower MFC. Both groups already differed in reticular pH and MFC during the low-RFCH period. Furthermore, higher RFCH amounts did not decrease the reticular pH in either of the 2 groups. Nevertheless, MFD was observed in both groups during the high-RFCH period compared with the low-RFCH period. Lower MFC in animals with lower reticular pH or during the high-RFCH period was associated with a shift in 18-carbon fatty acids toward trans-10 at the expense of trans-11 intermediates, which was observed in plasma as well as in milk samples. Moreover, lower MFC was accompanied by shifts in the relative abundance of specific bacteria in buccal samples. Genera Dialister, Sharpea, Carnobacterium, Acidaminococcus, and uncultured genera belonging to the Betaproteobacteria were more abundant in situations with greater trans-10 proportions.

Influence of selective treatment of bulls on the infestation of Haematobia irritans on untreated cows

The distribution of Hematobia irritans is not homogeneous in cattle populations. Generally, between 15% and 30% of bovines carry more than 50% of the flies, and higher infestations occur in bulls. In this study, the effect of treating the bulls with ear tags containing 40% diazinon on the infestation of flies on the herd during the breeding season was evaluated. Four groups of cattle were made, each containing one bull and 35 Braford cows. Groups 1 and 2 were on pastures in highlands. Groups 3 and 4 were on pastures in lowlands. At the beginning of the trial, each bull from Groups 1 and 3 was treated with an ear tag. Bulls from Groups 2 and 4 remained untreated. Weekly, for 10 weeks, horn flies were counted from each bull and 15 cows from each group. A repeated measures linear mixed model was used with cows as random effects. The number of horn flies in the treated groups was lower than that in the untreated group, suggesting that selective treatment of bulls could be an effective strategy to control horn flies on the herd. The number of flies was higher in the lowland than that in the highland groups, suggesting an effect of the environment on horn fly infestations. In addition, we estimated the cow level predictions from the model to estimate the cow effect on fly counts, and we compared those values with the observed weekly quartiles for each group. Fly-susceptible cows were defined as those for which the infestation of flies appeared in the upper quartile more than 50% of the weeks and in the lower quartile less than 20% of the weeks. In contrast, a fly-resistant cow was defined as one for which the fly counts appeared in the lower quartile more than 50% of the weeks and in the upper quartile less than 20% of the weeks. In all, 8.3% of the cows were susceptible and 15% were resistant. These results may be used to selectively treat bulls or to treat the bulls and the most susceptible cows during the breeding season.