Individual Cattle Research Articles

Optimum roughage proportion in barley-based feedlot cattle diets: growth performance, feeding behavior, and carcass traits.

High grain diets are fed to finishing beef cattle to maximize animal performance in a cost-effective manner. However, a small amount of roughage is incorporated in finishing diets to help prevent ruminal acidosis, although few studies have examined optimum roughage inclusion level in barley-based diets. The objective of the study was to evaluate the effects of roughage proportion in barley-based finishing diets on growth performance, feeding behavior, and carcass traits of feedlot cattle. Crossbred beef steers (n = 160; mean body weight ± SD, 349.7 ± 21.4 kg) were allocated to 20 pens that were assigned randomly to four dietary treatments (five pens of eight steers per treatment). The treatment diets contained barley silage at 0%, 4%, 8%, and 12% of dietary dry matter (DM). The remainder of the diets (DM basis) consisted of 80%, 76%, 72%, and 68% barley grain, respectively, 15% corn dried distiller's grains, 5% mineral and vitamin supplement, and 32 mg monensin/kg diet DM. The diets were fed as total mixed rations for ad libitum intake (minimum of 5% refusal) once per day. Cattle were weighed on 2 consecutive days at the start and end of the experiment and on 1 d every 3 wk throughout the experiment (124 d). Two pens for each treatment group were equipped with an electronic feeding system (GrowSafe Systems Ltd., Calgary, Alberta) to monitor feed intake and feeding behavior of individual cattle. The data for dry matter intake (DMI), average daily gain (ADG), gain:feed (G:F) ratio, and carcass traits were analyzed as a completely randomized design with fixed effect of barley silage proportion and pen replicate as experimental unit. Feeding behavior data were analyzed similarly, but with animal as experimental unit. Averaged over the study, DMI increased linearly (11.1, 11.3, 11.7, 11.8 kg/d; P = 0.001) as barley silage proportion increased from 0%, 4%, 8%, and 12% of DM, but ADG was not affected (carcass-adjusted,1.90, 1.85, 1.87, 1.89 kg/d; P ≥ 0.30). Consequently, G:F ratio decreased linearly (carcass-adjusted, 168.9, 163.8, 158.5, 160.6 g/kg DMI; P = 0.023). When averaged over the study, proportion of barley silage in the diet had no linear or quadratic effects (P > 0.10) on meal frequency, duration of meals, intermeal duration, or meal size, but eating rate decreased linearly with increasing silage proportion (P = 0.008). There was no diet effect on liver abscesses (P ≥ 0.92), and effects on carcass characteristics were minor or nonexistent. We conclude that increasing the proportion of barley silage in a feedlot finishing diet at the expense of barley grain to minimize the incidence of ruminal acidosis may decrease feed conversion efficiency.

Determination of genetic variation within the <i>DYRK2</i> gene and its associations with milk traits in cattle

To speed up the progress of marker-assisted selection (MAS) in cattle breeding, the dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2), cadherin 2 (CDH2), and kinesin family member 1A (KIF1A) genes were chosen based on our pervious genome-wide association study (GWAS) analysis results. DYRK2 is a kinase that may participate in cell growth and/or development; it shows phosphorylation activity toward serine, threonine, and tyrosine fragments of proteins, and it is different from other protein kinases. The CDH2 gene encodes a classic cadherin, which is a member of the cadherin superfamily. The protein encoded by KIF1A is a member of the kinesin family and plays a role in the transportation of membrane organelles along axon microtubules. We detected insertion/deletion (InDel) variation in these three candidate genes in 438 individual cattle (Xinjiang Brown cattle and Wagyu Luxi crossbreed cattle). Only DYRK2-P3-11 bp was polymorphic and genotyped. The polymorphism information content of DYRK2-P3-11 bp was 0.336. Correlation analyses showed that InDel polymorphism was significantly associated with six different milk traits. These findings may aid future analyses of InDel genotypes in cattle breeds, and speed up the progress of MAS in cattle breeding.

Assessing the effect of insecticide-treated cattle on tsetse abundance and trypanosome transmission at the wildlife-livestock interface in Serengeti, Tanzania.

In the absence of national control programmes against Rhodesian human African trypanosomiasis, farmer-led treatment of cattle with pyrethroid-based insecticides may be an effective strategy for foci at the edges of wildlife areas, but there is limited evidence to support this. We combined data on insecticide use by farmers, tsetse abundance and trypanosome prevalence, with mathematical models, to quantify the likely impact of insecticide-treated cattle. Sixteen percent of farmers reported treating cattle with a pyrethroid, and chemical analysis indicated 18% of individual cattle had been treated, in the previous week. Treatment of cattle was estimated to increase daily mortality of tsetse by 5–14%. Trypanosome prevalence in tsetse, predominantly from wildlife areas, was 1.25% for T. brucei s.l. and 0.03% for T. b. rhodesiense. For 750 cattle sampled from 48 herds, 2.3% were PCR positive for T. brucei s.l. and none for T. b. rhodesiense. Using mathematical models, we estimated there was 8–29% increase in mortality of tsetse in farming areas and this increase can explain the relatively low prevalence of T. brucei s.l. in cattle. Farmer-led treatment of cattle with pyrethroids is likely, in part, to be limiting the spill-over of human-infective trypanosomes from wildlife areas.

The prevalence and genomic context of Shiga toxin 2a genes in E. coli found in cattle.

Shiga toxin-producing Escherichia coli (STEC) that cause severe disease predominantly carry the toxin gene variant stx2a. However, the role of Shiga toxin in the ruminant reservoirs of this zoonotic pathogen is poorly understood and strains that cause severe disease in humans (HUSEC) likely constitute a small and atypical subset of the overall STEC flora. The aim of this study was to investigate the presence of stx2a in samples from cattle and to isolate and characterize stx2a-positive E. coli. In nationwide surveys in Sweden and Norway samples were collected from individual cattle or from cattle herds, respectively. Samples were tested for Shiga toxin genes by real-time PCR and amplicon sequencing and stx2a-positive isolates were whole genome sequenced. Among faecal samples from Sweden, stx1 was detected in 37%, stx2 in 53% and stx2a in 5% and in skin (ear) samples in 64%, 79% and 2% respectively. In Norway, 79% of the herds were positive for stx1, 93% for stx2 and 17% for stx2a. Based on amplicon sequencing the most common stx2 types in samples from Swedish cattle were stx2a and stx2d. Multilocus sequence typing (MLST) of 39 stx2a-positive isolates collected from both countries revealed substantial diversity with 19 different sequence types. Only a few classical LEE-positive strains similar to HUSEC were found among the stx2a-positive isolates, notably a single O121:H19 and an O26:H11. Lineages known to include LEE-negative HUSEC were also recovered including, such as O113:H21 (sequence type ST-223), O130:H11 (ST-297), and O101:H33 (ST-330). We conclude that E. coli encoding stx2a in cattle are ranging from strains similar to HUSEC to unknown STEC variants. Comparison of isolates from human HUS cases to related STEC from the ruminant reservoirs can help identify combinations of virulence attributes necessary to cause HUS, as well as provide a better understanding of the routes of infection for rare and emerging pathogenic STEC.

From unloading to trimming: studying bruising in individual slaughter cattle.

Livestock bruising is both an animal welfare concern and a detriment to the economic value of carcasses. Understanding the causes of bruising is challenging due to the numerous factors that have been shown to be related to bruise prevalence. While most cattle bruising studies collect and analyze data on truckload lots of cattle, this study followed a large number (n = 585) of individual animals from unloading through postmortem processing at five different slaughter plants. Both visual bruise presence and location was recorded postmortem prior to carcass trimming. By linking postmortem data to animal sex, breed, trailer compartment, and traumatic events at unloading, a rich analysis of a number of factors related to bruise prevalence was developed. Results showed varying levels of agreement with other published bruising studies, underscoring the complexity of assessing the factors that affect bruising. Bruising prevalence varied across different sex class types (P < 0.001); 36.5% of steers [95% confidence interval (CI): 31.7, 41.6; n = 378], 52.8% of cows (45.6, 60.0; 193), and 64.3% of bulls (no CI calculated due to sample size; 14) were bruised. There was a difference in bruise prevalence by trailer compartment (P = 0.035) in potbelly trailers, indicating that cattle transported in the top deck were less likely to be bruised (95% CI: 26.6, 40.4; n = 63) compared to cattle that were transported in the bottom deck (95% CI: 39.6, 54.2; n = 89). Results indicated that visual assessment of bruising underestimated carcass bruise trimming. While 42.6% of the carcasses were visibly bruised, 57.9% of carcasses were trimmed due to bruising, suggesting that visual assessment is not able to capture all of the carcass loss associated with bruising. Furthermore, bruises that appeared small visually were often indicators of larger, subsurface bruising, creating an “iceberg effect” of trim loss due to bruising.

A Targeted “Next-Generation” Sequencing-Informatic Approach to Define Genetic Diversity in Theileria orientalis Populations within Individual Cattle: Proof-of-Principle

Oriental theileriosis is an economically important tickborne disease of bovines, caused by some members of the Theileria orientalis complex. Currently, 11 distinct operational taxonomic units (OTUs), or genotypes, are recognized based on their major piroplasm surface protein (MPSP) gene sequences. Two of these genotypes (i.e., chitose and ikeda) are recognized as pathogenic in cattle, causing significant disease in countries of the Asia-Pacific region. However, the true extent of genetic variation and associated virulence/pathogenicity within this complex is unknown. Here, we undertook a proof-of-principle study of a small panel of genomic DNAs (n = 13) from blood samples originating from individual cattle known to harbor T. orientalis, in order to assess the performance of a targeted “next-generation” sequencing-informatic approach to identify genotypes. Five genotypes (chitose, ikeda, buffeli, type 4, and type 5) were defined; multiple genotypes were found within individual samples, with dominant and minor sequence types representing most genotypes. This study indicates that this sequencing-informatic workflow could be useful to assess the nature and extent of genetic variation within and among populations of T. orientalis on a large scale, and to potentially employ panels of distinct gene markers for expanded molecular epidemiological investigations of socioeconomically important protistan pathogens more generally.

Identification of Microbial Genetic Capacities and Potential Mechanisms Within the Rumen Microbiome Explaining Differences in Beef Cattle Feed Efficiency.

In this study, Bos Taurus cattle offered one high concentrate diet (92% concentrate-8% straw) during two independent trials allowed us to classify 72 animals comprising of two cattle breeds as “Low” or “High” feed efficiency groups. Digesta samples were taken from individual beef cattle at the abattoir. After metagenomic sequencing, the rumen microbiome composition and genes were determined. Applying a targeted approach based on current biological evidence, 27 genes associated with host-microbiome interaction activities were selected. Partial least square analysis enabled the identification of the most significant genes and genera of feed efficiency (VIP > 0.8) across years of the trial and breeds when comparing all potential genes or genera together. As a result, limited number of genes explained about 40% of the variability in both feed efficiency indicators. Combining information from rumen metagenome-assembled genomes and partial least square analysis results, microbial genera carrying these genes were determined and indicated that a limited number of important genera impacting on feed efficiency. In addition, potential mechanisms explaining significant difference between Low and High feed efficiency animals were analyzed considering, based on the literature, their gastrointestinal location of action. High feed efficiency animals were associated with microbial species including several Eubacterium having the genetic capacity to form biofilm or releasing metabolites like butyrate or propionate known to provide a greater contribution to cattle energy requirements compared to acetate. Populations associated with fucose sensing or hemolysin production, both mechanisms specifically described in the lower gut by activating the immune system to compete with pathogenic colonizers, were also identified to affect feed efficiency using rumen microbiome information. Microbial mechanisms associated with low feed efficiency animals involved potential pathogens within Proteobacteria and Spirochaetales, releasing less energetic substrates (e.g., acetate) or producing sialic acid to avoid the host immune system. Therefore, this study focusing on genes known to be involved in host-microbiome interaction improved the identification of rumen microbial genetic capacities and potential mechanisms significantly impacting on feed efficiency in beef cattle fed high concentrate diet.

Foot-and-Mouth Disease Surveillance Using Pooled Milk on a Large-Scale Dairy Farm in an Endemic Setting.

Pooled milk is used for the surveillance of several diseases of livestock. Previous studies demonstrated the detection of foot-and-mouth disease virus (FMDV) in the milk of infected animals at high dilutions, and consequently, the collection of pooled milk samples could be used to enhance FMD surveillance. This study evaluated pooled milk for FMDV surveillance on a large-scale dairy farm that experienced two FMD outbreaks caused by the A/ASIA/G-VII and O/ME-SA/Ind-2001d lineages, despite regular vaccination and strict biosecurity practices. FMDV RNA was detected in 42 (5.7%) of the 732 pooled milk samples, and typing information was concordant with diagnostic reports of clinical disease. The FMDV positive milk samples were temporally clustered around reports of new clinical cases, but with a wider distribution. For further investigation, a model was established to predict real-time RT-PCR (rRT-PCR) CT values using individual cattle movement data, clinical disease records and virus excretion data from previous experimental studies. The model explained some of the instances where there were positive results by rRT-PCR, but no new clinical cases and suggested that subclinical infection occurred during the study period. Further studies are required to investigate the effect of vaccination on FMDV excretion in milk, and to evaluate more representative sampling methods. However, the results from this pilot study indicate that testing pooled milk by rRT-PCR may be valuable for FMD surveillance and has provided evidence of subclinical virus infection in vaccinated herds that could be important in the epidemiology of FMD in endemic countries where vaccination is used.

Cattle identification using muzzle print images based on feature fusion

Individual identification of animals is an important means to modernize the livestock industry. In recent years, the research on individual identification of cattle has also received more and more attention. Individual cattle identification is necessary for many important reasons including registration, traceability, production management and animal disease control. Biometric features are unique, which often do not change over time. In this paper, muzzle print is used as biometric feature. The fusion of texture features extracted from Weber Local Descriptor(WLD) and local binary pattern was used to represent individual cattle. Some improvements were made to WLD algorithm. Finally, support vector machine was employed to identify head of cattle from their fusion feature. The proposed method achieved 96.5% identification accuracy.

A cross sectional study of prevalence and risk factors associated with subclinical mastitis and intramammary infections, in dairy herds linked to milk collection centers in Rwanda

The objective of this cross-sectional study was to investigate prevalence, causative udder pathogens and their antimicrobial resistance (AMR), as well as cow and herd risk factors associated with subclinical mastitis (SCM = cows with at least one udder quarter with california mastitis test (CMT) score > 2) and intramammary infections (IMI) caused by Staphylococcus(S.) aureus or Non aureus staphylococci (NAS) in dairy cows linked to Milk Collection Centers (MCCs) in Rwanda. Screening for SCM with the CMT was done on 572 cows from 404 herds linked to two MCCs in each of four provinces. Milk from udder quarters with a CMT score ≥3 (scale 1–5) was sampled for bacteriological analysis. Antimicrobial resistance was evaluated in 60 selected S. aureus isolates. Multivariable mixed effect and ordinary logistic regression analyses were performed to identify cow and herd level risk factors associated with SCM, NAS or S. aureus IMI in cows. The prevalence of SCM was 37.3 % at quarter level and 62.0 % at cow level. Bacteria were isolated 73.7 % of the cultured milk samples, whereas 23.3 % were culture-negative and 3.0 % were contaminated. Staphylococcus aureus and NAS were the most prevalent pathogens, representing more than half of all bacteriological findings. Staphylococcus chromogenes and S. epidermidis were the most prevalent NAS species identified. Of the S. aureus strains 83.3 % were resistant for penicillin, 100 % for clindamycin and 20 % tetracycline. The risk factor analysis showed that an increased stage of lactation, dirty udder and legs in single cow herds and lack of calf suckling the dam, dirty udder and legs and lack of feeding cow after milking in multiple cow herds were significantly (P < 0.05) associated with an increased odds of SCM. Similarly, increasing stage of lactation in single cow herds, and housing cows in individual cattle kraal or on earthen floor and hand washing between cows during milking in multiple cow herds were associated with increased odds for NAS IMI. Poor hygiene of milking area in single cow herds and absence of foremilk stripping in multiple cow herds were significantly (P < 0.05) associated with increased odds for S. aureus IMI in cows. In conclusion, SCM prevalence was high across MCCs. The majority of identified pathogens were contagious in nature and they exhibited resistance to penicillin. Control of the identified risks factors and improved biosecurity through adoption of best practices, and farmer training could contribute to lowering SCM prevalence in Rwanda.

Longitudinal Characterization of Prevalence and Concentration of Shiga Toxin-Producing Escherichia coli Serogroups in Feces of Individual Feedlot Cattle.

The objective of this study was to quantify the frequency, distribution, and variability of fecal shedding and super-shedding of Shiga toxin-producing Escherichia coli (STEC) serogroups O26, O45, O103, O111, O121, O145, and O157 in feedlot cattle over time. A total of 750 fecal grab samples were collected over a 5-week period (June-July 2017) from 150 cattle housed in 10 pens at a commercial feedlot operation. Samples were subjected to culture-based methods and real-time quantitative polymerase chain reaction for STEC detection and quantification. Cumulative animal-level prevalence estimates were 9.5%, 5.2%, and 15.8% for STEC O157, non-O157 STEC serogroups only (STEC-6), and for all STEC serogroups tested (STEC-7), respectively, with the prevalence of STEC O157 and STEC-7 significantly differing between weeks (p < 0.01). Most of the variability in fecal shedding for STEC O157, STEC-6, and STEC-7 was between pens, rather than between cattle. Over the 5-week period, 10 animals (6.7%) persistently shed STEC non-O157 over 3 or more consecutive weeks, whereas 2 animals (1.3%) intermittently shed STEC non-O157 on nonconsecutive weeks. Fifteen animals (10.0%) shed multiple STEC serogroups within the same fecal sample and five animals (3.3%) shed multiple serogroups at super-shedding levels, higher than 104 CFU (colony-forming units)/g, in the same sample. The presence of a super-shedder in a pen was significantly associated with a greater within pen-level prevalence of STEC-6 (p = 0.01). This study gives further insights into intermittent and persistent shedding and super-shedding patterns of STEC serogroups in individual feedlot cattle, which can enable the development and effective application of preharvest and periharvest interventions, as well as surveillance strategies, for these pathogens.

Veterinary growth promoters in cattle feedlot runoff: estrogenic activity and potential effects on the rat male reproductive system.

The contribution of veterinary growth promoters (VGP) to the environmental burden of endocrine-disrupting chemicals (EDCs) is largely unknown. At cattle feedlots, the excrement of cattle may contain VGPs, which can contaminate aquatic systems and pose reproductive health risks. The study identifies VGPs used at cattle feedlots in South Africa and confirms associated estrogenic activity in feedlot runoff water. Using a rat model, we investigate the potential reproductive health effects and thyroid function of an environmentally relevant mixture of VGPs. Collected water samples had low levels of selected VGPs, and estrogenic activity was detected in the T47D-KBluc bioassay. Rats exposed to VGP had significant adverse effects on male reproductive health, including shortened anogenital distance, lowered sperm counts, disorganized seminiferous tubules, and thyroid parameters. In conclusion, VGP can contribute to complex environmental EDC mixtures and may adversely affect the reproductive and thyroid health of both humans and wildlife. The varied topography of individual cattle feedlots will govern the rate and extent of effluent runoff, thus continuous monitoring of VGPs in aquatic systems surrounding cattle feedlots is necessary.

A Framework for Real-time Cattle Monitoring using Multimedia Networks

Monitoring cattle behaviour has been a perpetual challenge in animal husbandry and animal breeding. Various methods have been used in the past to monitor the behaviour of cattle and their grazing patterns. We proposed a framework for real time cattle monitoring using multimedia networks. The study observes the grazing patterns of cattle and their behaviours in the grazing field. In order to accomplish the above observation, global positioning system monitoring collar for cattle is utilized; this technology monitors the activities of individual cattle during grazing through a networked system. The materials used in carrying out the work include cattle, waterproof global positioning system tracking collars (TR20) for cattle, and supporting application software by Sigfox’s global Internet of Things network. The paddock size was 121 by 174 m. Forage was predominantly agricultural plants. Cattle weighing up to 580 kg were used. The collared cattle were used to initiate all data collections. Latitude and longitude information of location was cumulatively stored in memory that is on-boarded and big enough for the fixing of position. Each fix record is comprised of corresponding estimation of height, date and time of global positioning system, precision value dilution, status of fix, temperature, including horizontal and vertical activity sensor counts in intervals that are fixed. Units of collar were well compacted, robust, and of about 1 kg in weight. Location fixes for over a day period were showed through testing to be accurate, at roughly 95% for eight minutes of time after correction of the difference. There was no bias of direction on the part of errors that have consistency with other studies’ finding.

Echinococcus granulosus in the Northern Territory, Australia: hydatid disease reported in beef cattle from the region

Hydatid disease in beef cattle has been reported to be widespread throughout Australia, but cattle bred and raised in the Northern Territory were previously believed to be free of the disease. Between 2010 and 2016, 1061 cattle from the Northern Territory were slaughtered at a New South Wales abattoir and inspected for hydatid disease. The proportion of cattle reported infected with hydatid disease was 3.5%. Individual cattle identification numbers indicated that the cattle included in the study had most likely remained within the Northern Territory from birth until immediately prior to slaughter, so were assumed to have become infected within the region. We suspect that the sylvatic cycle of Echinococcus granulosus transmission could be responsible for infection of cattle in this region.

Evaluation of remote monitoring units for estimating body weight and supplement intake of grazing cattle

Automated weighing systems to monitor BW and supplement intake (SI) of individual grazing cattle are being developed to better understand the seasonal nutrition and performance of grazing livestock. This study established (1) the accuracy and repeatability of a commercial walk-over weighing (WoW) system for estimating BW and (2) the accuracy of an automatic supplement weighing (ASW) unit for estimating SI based on measuring time spent at the unit. The WoW and ASW units monitored BW and SI of 112 cattle consisting of 55 cows and 57 calves grazed on a 32.5 ha paddock for 41 days, with an average of 258 BW records collected per day. Static BWs were recorded at each mustering event (n = 7) and were compared to repeated measurements collected by the WoW on the day of each mustering event. Body weight was overestimated by the WoW, with the predicted BW of calves and cows averaging 10 and 21 kg heavier, respectively, than actual, and root MS prediction errors (RMSPE) of 5.1% and 5.5% of the static BW, respectively. For both calves and cows, 38% of the MS prediction errors (MSPE) was mean bias (MB) error and 9% of MSPE was slope bias error. The concordance correlation coefficient (CCC; 0.90 v. 0.80) and modelling efficiency (MEF; 0.78 v. 0.62) of WoW BW for calves were higher than for cows, indicating that the predicted values were deviating from a 1 : 1 relationship and in particular as weight increases. A rolling average across five or more consecutive BW measures improved the accuracy of the WoW BW estimates. Regarding estimates of SI, the aggregated time the herd spent at the ASW unit was strongly associated with total SI (R2 = 0.92; P < 0.001). Further, positive linear relationships (P < 0.001) existed between cumulative weighted time spent at the ASW unit (min) and concentration of fenbendazole (FBZ) used as an intake marker and its derivatives (oxfendazole and oxfendazole sulfone) in the plasma of individual cows, with R2 of 0.54, 0.73 and 0.75, respectively. Although the WoW overestimated static BW, the low bias in the slope indicated that a linear regression model could be developed to adjust the WoW BW to reduce the MB and improve the estimate of WoW BW. The significant positive relationship between time spent at the ASW unit and individual blood FBZ concentration identified the suitability of the ASW unit for estimating SI by grazing cattle.

Financial and economic analyses of the impact of cattle mastitis on the profitability of Egyptian dairy farms.

Aim:This study aimed to evaluate and quantify the different factors affecting the costs of mastitis in cattle, to quantify the annual and monthly financial losses attributed to mastitis, and to estimate production losses using average linear scores found on The Dairy Herd Improvement Association somatic cell count (SCC) sheets and bulk tank SCC per lactation number.Materials and Methods:All data (bovine mastitis-associated costs and expenditures in Egyptian dairy herds) were analyzed using SPSS/PCT, 2001. A partial budget technique using spreadsheet software and the general linear model procedure was used to analyze the productive and financial measures.Results:Mastitis was present in 57.1% of cows (240/420), while clinical mastitis (CM) was present in 19% of them (80/420). The geometric mean of SCC/ml in bulk tank milk samples of 150 cattle dairy farms was 556.3×103. The annual subclinical mastitis (SCM)-related economic loss was 21,933,258.6 LE, and the two most important cost components were the subsequent decrease in milk production and quality premium losses (93% and 7% of SCM costs, respectively). The quality premium loss was 1,369,602.1 LE. On the other hand, the annual economic loss due to decreased milk production as a result of SCM was 20,563,656.5 LE. The total cost of 80 CM cases, including the failure and preventive costs, was 1,196,871.4 LE, including 1,169,150.4 LE failure costs (106,336.0 LE in direct costs and 1,062,814.4 LE in indirect costs) and 27,721.0 LE preventive costs. The average cost per CM case was 28,760.9 LE, including veterinary time and consultation fees of 250.0 LE (1%), labor 562.5 LE (2%), premature culling 736,000.0 LE (77%), decreased milk production 4085.18 LE (13.7%), discarded milk 185.3 LE (1%), and drugs and treatments 328.9 LE (1%). The total costs of CM (expenditures) extra control and preventive measures, including the diagnosis of CM for 80 cows annually in 20 Egyptian dairy farms were 27,721.0 LE, representing 346.5 LE or 1% of the total cost of CM cases. The cost of monitoring and diagnostic measures was 8635.2 LE, representing 107.9 LE or 1% of the total cost of a case of CM.Conclusion:The method used for cost estimation, in this study, is highly adaptable to individual cattle farms and had a major role in assessing specific control and management measures. The concepts described in this paper help to improve our understanding of the full economic impact of clinical and subclinical mastitis in cattle in Egypt. Assessing the economic losses from mastitis to determine the economic costs and losses occurring in Egyptian dairy farms is critical for encouraging farmers to acknowledge the scale of the problem and implement effective management practices aimed at improving mastitis control and reducing the associated costs.

94 Efficient generation of myostatin mutation in Korean beef cattle

In recent years, CRISPR/Cas9 has become known as a powerful tool for generating genetically modified cells or animal models with its site-specific gene editing capability. Because myostatin (MSTN) is associated with muscle differentiation and growth, ablation of MSTN would be ideal for studying phenotypes associated with muscle growth in beef cattle. The aim of this study is to produce Korean beef cattle with MSTN mutation through microinjection of CRISPR/Cas9. For this study, ovaries of Korean beef cattle were obtained from slaughterhouses; 122 immature oocytes were aspirated from 8 Korean beef cattle. The oocytes were matured in tissue culture medium 199-based medium for 22h and inseminated with frozen-thawed semen to produce zygotes. All 122 zygotes were directly injected with 200ng of Cas9 mRNA and 100ng of sgRNA for MSTN after IVF and were cultured for 7 days in two-step chemically defined medium. Each embryo from the individual cattle was cultured separately to distinguish its lineage. After 7 d, 29 (23.8±8.9) blastocysts were recovered, and all blastocysts were assessed with T7 endonuclease (T7E1) mutation assay to check for mutations at the MSTN locus. Based on T7E1, 26 out of 29 blastocysts (89.7±10.5%) had heterozygous mutation in the MSTN gene. After analysis, additional blastocysts were produced and transferred into 14 surrogates. All surrogates were diagnosed for pregnancy via rectal palpation and ultrasonography at Day 55, at which time normal fetuses and embryonic sacs were confirmed in 10 surrogates. In conclusion, these data demonstrate that CRISPR/Cas9 could be employed as an efficient method to genetically modify the MSTN gene in Korean beef cattle.

Vocal individuality of Holstein-Friesian cattle is maintained across putatively positive and negative farming contexts

Cattle mother-offspring contact calls encode individual-identity information; however, it is unknown whether cattle are able to maintain individuality when vocalising to familiar conspecifics over other positively and negatively valenced farming contexts. Accordingly, we recorded 333 high-frequency vocalisations from 13 Holstein-Friesian heifers during oestrus and anticipation of feed (putatively positive), as well as denied feed access and upon both physical and physical & visual isolation from conspecifics (putatively negative). We measured 21 source-related and nonlinear vocal parameters and stepwise discriminant function analyses (DFA) were performed. Calls were divided into positive (n = 170) and negative valence (n = 163) with each valence acting as a ‘training set’ to classify calls in the oppositely valenced ‘test set’. Furthermore, MANOVAs were conducted to determine which vocal parameters were implicated in individual distinctiveness. Within the putatively positive ‘training set’, the cross-validated DFA correctly classified 68.2% of the putatively positive calls and 52.1% of the putatively negative calls to the correct individual, respectively. Within the putatively negative ‘training set’, the cross-validated DFA correctly assigned 60.1% of putatively negative calls and 49.4% of putatively positive calls to the correct individual, respectively. All DFAs exceeded chance expectations indicating that vocal individuality of high-frequency calls is maintained across putatively positive and negative valence, with all vocal parameters except subharmonics responsible for this individual distinctiveness. This study shows that cattle vocal individuality of high-frequency calls is stable across different emotionally loaded farming contexts. Individual distinctiveness is likely to attract social support from conspecifics, and knowledge of these individuality cues could assist farmers in detecting individual cattle for welfare or production purposes.

Endemic foot and mouth disease: pastoral in-herd disease dynamics in sub-Saharan Africa

Foot and mouth disease (FMD) burden disproportionally affects Africa where it is considered endemic. Smallholder livestock keepers experience significant losses due to disease, but the dynamics and mechanisms underlying persistence at the herd-level and beyond remain poorly understood. We address this knowledge gap using stochastic, compartmental modelling to explore FMD virus (FMDV) persistence, outbreak dynamics and disease burden in individual cattle herds within an endemic setting. Our analysis suggests repeated introduction of virus from outside the herd is required for long-term viral persistence, irrespective of carrier presence. Risk of new disease exposures resulting in significant secondary outbreaks is reduced by the presence of immune individuals giving rise to a period of reduced risk, the predicted duration of which suggests that multiple strains of FMDV are responsible for observed yearly herd-level outbreaks. Our analysis suggests management of population turnover could potentially reduce disease burden and deliberate infection of cattle, practiced by local livestock keepers in parts of Africa, has little effect on the duration of the reduced risk period but increases disease burden. This work suggests that FMD control should be implemented beyond individual herds but, in the interim, herd management may be used to reduced FMD impact to livestock keepers.

Comparative evaluation of two commercial ELISA kits for detection of antibodies against Akabane virus in cattle serum

BackgroundAkabane disease (AD), a barrier to international trade for endemic areas with far economic impact on the countries, is caused by Akabane virus (AKAV). Commercial enzyme-linked immunosorbent assay (ELISA) is a commonly used diagnostic technique for AKAV infection, including the IDEXX and IDVET ELISA kits. However, the comparative evaluation of the IDEXX and IDVET ELISA kits has not been published. The object of this study was to evaluate the test performance of the two commercial ELISA kits in detecting serum anti-AKAV antibodies in cattle.ResultsWith virus neutralization test (VNT) as the “relative gold standard”, the diagnostic sensitivity (DSe) was 80.39% (123/153) and 93.46% (143/153) for the IDEXX and IDVET ELISA kit, when suspect samples were included. The diagnostic specificity (DSp) for the IDEXX and IDVET ELISA kit was 93.48% (502/537) and 82.31% (442/537), respectively.ConclusionBoth of the tested ELISA kits could be applied to detect antibodies against AKAV in cattle serum. The IDVET ELISA kit had a higher DSe. The IDEXX ELISA kit possessed the higher DSp. These results have important implications if the kits are used to screen herds or individual cattle in surveillance programs, or at border crossings for import-export inspection and quarantine.