Open Herd Research Articles

Respiratory illness in young and adult cattle caused by bovine viral diarrhea virus subgenotype 2b in singular and mixed bacterial infection in a BVDV-vaccinated dairy herd.

Bovine respiratory disease (BRD) is a common global health problem in dairy cattle. The definitive diagnosis of BRD is complex because its etiology involves several predisposing and determining factors. This report describes the etiology of a BRD outbreak in a dairy herd in the mesoregion of Central Eastern Paraná, which simultaneously affected young (calves and heifers) and adult (cows) Holstein-Friesian cattle. Nine biological samples, consisting of five lung samples from two cows and three suckling calves, and four nasal swab samples from heifers, were used for etiological diagnosis. The nucleic acids extracted from lung fragments and nasal swabs were subjected to PCR and RT-PCR assays for partial amplification of the genes of five viruses [bovine viral diarrhea virus (BVDV), bovine alphaherpesvirus 1 (BoAHV1), bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus 3 (BPIV-3), and bovine coronavirus (BCoV)] and four bacteria (Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni) involved in the etiology of BRD. All nine biological samples from the animals with BRD tested negative for BoAHV1, BRSV, BPIV-3, BCoV, and H. somni. Therefore, the involvement of these microorganisms in the etiology of BRD outbreak can be ruled out. It was possible to identify the presence of BVDV and M. bovis in singular and mixed infections of the lower respiratory tract in cattle. BVDV was also identified in two nasal swabs: one as a single etiological agent and the other in association with two bacteria (P. multocida and M. haemolytica). The phylogenetic analysis conducted in the nucleotide sequence of the 5'UTR region and Npro gene of the BVDV amplicons demonstrated that the BVDV field strains of this BRD outbreak belong to subgenotype 2b. To the best of our knowledge, this is the first report of BVDV-2b involvement in the etiology of BRD in Brazil. Finally, it is necessary to highlight that the cattle were obtained from an open dairy herd with biannual vaccinations for BVDV-1a and - 2a.

Seroprevalence and associated risk factors for Neospora caninum infection in dairy cattle in South Africa

Bovine neosporosis is a widespread parasitic disease associated with significant economic losses. Its effects on the reproductive performance of cows have resulted in losses that run into the hundreds of millions of US dollars in dairy industries in various countries (Reichel et al., Int J Parasitol 43:133–142, 2013). Due to outdated and scant information on the occurrence of Neospora caninum infection in South Africa, the study aimed to determine the seroprevalence and risk factors associated with infection in dairy cattle in South Africa. A total of 1401 blood samples were randomly collected from cattle on 48 dairy farms in seven of the nine provinces in South Africa. A close-ended questionnaire was used in a cross-sectional study to obtain farm-level and animal-level data. Serological testing was done using a commercial IDvet Screen® Neospora caninum Indirect ELISA. An overall seroprevalence, adjusted for test sensitivity and specificity, of 2.3% (95% CI, 1.3–4.1) was detected and 48% (23/48) of sampled farms had at least one animal testing positive. The highest seroprevalence of N. caninum was in the KwaZulu-Natal province with 7.5% (95% CI, 3.8–14.3), and the lowest in Western Cape with 0.1% (95% CI, 0–1.2). The highest within-farm seroprevalence of 25% was detected on a farm in the North West Province. In a multivariable logistic regression model, the odds of N. caninum seropositivity were higher in Holstein–Friesian cattle when compared to other breeds. Good hygiene was identified as a protective factor. Cattle left out on pasture had increased odds of testing positive for N. caninum compared to those that were penned. The odds of testing seropositive for N. caninum was higher on farms that practised segregation of cattle into different age groups. The purchase of replacement animals was a significant risk factor, as open herds had increased odds of N. caninum seropositivity. Cattle on farms that did not have a specific calving location were more likely to be seropositive. This is the first such study in South Africa and shows that N. caninum is widely distributed in the country at a low seroprevalence, but it may be a cause of concern on certain farms.

Outbreak of persistently infected heifer calves with bovine viral diarrhea virus subgenotypes 1b and 1d in a BVDV-vaccinated open dairy herd

Bovine viral diarrhea virus (BVDV) infection has a significant economic impact on beef and dairy industries worldwide. Fetal infection with a non-cytopathic strain may lead to the birth of persistently infected (PI) offspring, which is the main event in the epidemiological chain of BVDV infection. This report describes the birth of 99 BVDV-PI heifer calves within 52 days of birth in a regular BVDV-vaccinated Brazilian dairy cattle herd and the subgenotypes of the infecting field strains. This study was conducted in a high-yielding open dairy cattle herd that frequently acquired heifers from neighboring areas for replacement. The farm monitors the birth of PI calves by screening all calves born using an ELISA (IDEXX) for BVDV antigen detection. All calves aged 1–7 days were evaluated. For positive and suspected results, the ELISA was repeated when the calves were close to one month old. A total of 294 heifer calves were evaluated between February and March 2021. Of these, 99 (33.7 %) had positive ELISA results and were considered PI calves. To evaluate the predominant BVDV species and subgenotypes in this outbreak, whole blood samples were collected from 31 calves born during the study period. All samples were submitted to the RT-PCR assay for the partial amplification of the BVDV 5′-UTR region, and these amplicons were subjected to nucleotide sequencing. Phylogenetic analysis identified BVDV-1b and BVDV-1d in 16 and 13 heifer calves, respectively. In two calves, it was not possible to determine the BVDV-1 subgenotype. Detection of PI animals and monitoring of circulating BVDV subgenotype strains are central to disease control. This study shows that regular BVDV vaccination alone may be insufficient to prevent BVDV infection in high-yielding open dairy cattle herds. Other biosecurity measures must be adopted to avoid the purchase of cattle with acute infections by BVDV or BVDV-PI, which can cause a break in the health profile of the herd and economic losses.

Management of Haemaphysalis longicornis (Acari: Ixodidae) on a cow-calf farm in East Tennessee, USA.

Haemaphysalis longicornis Neumann is an exotic and invasive tick species rapidly expanding across the United States. Large infestations of these ticks on cattle can cause anemia, and in eastern regions of the country, they are transmitting Theileria orientalis Ikeda within herds. Methods for managing H. longicornis in the environment are rarely successful and rely on chemicals. To document population effects from producer management decisions, we investigated the change in H. longicornis populations to different tick management practices chosen by producers at 3 different H. longicornis-infested farms. Farm 1 kept a closed herd, chose to cut brush monthly, used on-animal acaricides, and allowed us to drag weekly. Farm 2 kept an open herd, chose to cut brush yearly, did not use on-animal acaricides, and allowed us to drag for ticks weekly/monthly. Farm 3 kept an open herd, chose to cut brush yearly, used on-animal acaracides, and allowed us to drag for ticks monthly. We assessed H. longicornis populations responding to those methods over time using active surveillance methods at each farm. Management decisions on Farms 1 and 3 significantly reduced H. longicornis on farms. Importantly, Farm 1 management decisions reduced the chance of a tick being present by 90%; the number of questing ticks collected fell from 5,000 to 12 H. longicornis in 2 years. Therefore, combined management strategies such as keeping a closed herd, use of on-animal chemical control, mechanical control, and reducing the amount of vegetation on farms were effective ways for producers to manage Haemaphysalis longicornis Neuman (Ixodidae).

Causes and Effects of Stillbirths on Days Open and Cow Herd Survival in Holstein Friesian Cows

The aim of this retrospective study was to investigate the causes and the effects of stillbirth on the number of days open and cow herd survival in subsequent lactation of Holstein Friesian cows. A total of 1371 calvings from research dairy farm were used. Stillbirth in calves was defined as the death of a fetus before or during calving at full term (≥270 days of gestation) or within 24 hours after calving. During the period from January 2006 to December 2017 a percent of 95.04% of the calvings were with live calves, and 4.96% of the calvings were stillbirths. The major causes of stillbirth identified were: calving difficulty, parity of the cows, and sex of the calves at calving. A five point scale was used to assess calving difficulties, and numbers 1, 2 and 3 were considered unassisted calvings and number 4 and 5 as assisted. The twin calvings were not taken into account. Days open were measured as days from first calving to conception, and cow herd survival from first calving to culling or death. Trend test and multivariate data analysis were used. The findings revealed that primiparous cows were at higher risk of having stillbirths compared with multiparous cows. Cows that were at calving male calves were at higher risk of having stillbirths compared with cows that had female calves at calving. Also, cows with assisted calving were at higher risk of having stillbirths compared with cows with unassisted calvings. Cows with stillbirths had a increase mean of days open with 32 days. Cow herd survival was better in the cows with live calves at calving compared with the cows that had stillbirth at calvings.

Holstein Cattle Face Re-Identification Unifying Global and Part Feature Deep Network with Attention Mechanism.

Simple SummaryAutomated and non-intrusive recognition of individual livestock such as a cow or a pig is a vital requirement for obtaining individual information, something which has played a significant role in the intelligent management and welfare of livestock. However, individual cow identification remains a demanding task mainly due to the quite yet subtle inter-class differences in an open herd setting. The objective of this study is to develop a novel unified global and part feature deep network model (GPN) to learn more discriminative and robust features that can facilitate cow face representation for re-identification and verification. The results of various contrast experiments on collecting the large-scale cow face dataset show that the proposed GPN model outperforms the existing representative re-identification methods, and the further improved GPN-ST model has a higher accuracy rate (up by 2.8% and 2.2% respectively) in Rank-1 and mAP, compared with the GPN model. In conclusion, using the proposed framework can effectively ameliorate the performance of cow face re-identification.In precision dairy farming, computer vision-based approaches have been widely employed to monitor the cattle conditions (e.g., the physical, physiology, health and welfare). To this end, the accurate and effective identification of individual cow is a prerequisite. In this paper, a deep learning re-identification network model, Global and Part Network (GPN), is proposed to identify individual cow face. The GPN model, with ResNet50 as backbone network to generate a pooling of feature maps, builds three branch modules (Middle branch, Global branch and Part branch) to learn more discriminative and robust feature representation from the maps. Specifically, the Middle branch and the Global branch separately extract the global features of middle dimension and high dimension from the maps, and the Part branch extracts the local features in the unified block, all of which are integrated to act as the feature representation for cow face re-identification. By performing such strategies, the GPN model not only extracts the discriminative global and local features, but also learns the subtle differences among different cow faces. To further improve the performance of the proposed framework, a Global and Part Network with Spatial Transform (GPN-ST) model is also developed to incorporate an attention mechanism module in the Part branch. Additionally, to test the efficiency of the proposed approach, a large-scale cow face dataset is constructed, which contains 130,000 images with 3000 cows under different conditions (e.g., occlusion, change of viewpoints and illumination, blur, and background clutters). The results of various contrast experiments show that the GPN outperforms the representative re-identification methods, and the improved GPN-ST model has a higher accuracy rate (up by 2.8% and 2.2% respectively) in Rank-1 and mAP, compared with the GPN model. In conclusion, using the Global and Part feature deep network with attention mechanism can effectively ameliorate the efficiency of cow face re-identification.

The use of milk Fourier-transform mid-infrared spectroscopy to diagnose pregnancy and determine spectral regional associations with pregnancy in US dairy cows

Accurate early diagnosis of pregnancy is important for timely reproductive management of dairy farms. Fourier-transform mid-infrared (FT-MIR) milk spectral data are routinely used for determining milk components such as fat and protein, whereas milk composition is known to change with advancing stages of pregnancy. The objectives of this study were to compare partial least squares discriminant analysis (PLS-DA) and a Bayesian variable selection regression model (BayesC) for the diagnosis of pregnancy status (PS) from milk FT-MIR data and to infer any spectral regions that might be highly associated with PS at various stages of pregnancy. Conception dates on confirmed pregnant cows were obtained from Holstein cows within 123 herds in Michigan, Ohio, and Indiana during 2018 and 2019. Milk samples from these pregnant cows at 7 different stages of pregnancy were case-control matched to open contemporary herd mates to be within the same stage (±10 d for days in milk) of lactation for the same milk sample test date. The FT-MIR data were obtained for all of these milk samples. Ten-fold herd-independent cross-validation was used to compare PLS-DA versus BayesC using the area under the receiver operating characteristic curve (AUC). The BayesC model demonstrated higher mean AUC compared with PLS-DA at all stages exceeding 60 d of pregnancy. The mean BayesC AUC at stage 1 (1-30 d) was 0.58 ± 0.02, which was superior to a random guess (AUC = 0.50) yet too low to be of practical use. The mean BayesC AUC at stage 7 (≥180 d) was 0.13 greater compared with that of stage 1 (1-30 d) and 0.07 to 0.10 greater compared with stages 2, 3, 4, 5, and 6 (31-180 d in 30-d increments). The mean AUC of stages 2 to 6 were 0.03 to 0.06 greater compared with stage 1 yet again too low to be of practical use. Because of high multicollinearity between many adjacent wavenumbers, a spatially constrained clustering algorithm was used to adaptively partition wavenumbers into 68 windows before inferring associations of spectral regions with pregnancy. Pregnancy status was highly associated with wavenumber windows 1,063 to 1,134 cm-1, 1,201 to 1,257 cm-1, and 1,260 to 1,432 cm-1 based on an estimated BayesC posterior probability of association (PPA) approaching 100% for each of these windows at all pregnancy stages. Other windows ranging from 1,730 to 1,764 cm-1, 1,775 to 1,992 cm-1, 1,995 to 2,163 cm-1, and 2,167 to 2,316 cm-1 had varying medium to high PPA (30% to 100%) across stages. The estimated PPA in wavenumber regions from 1,477 to 1,507 cm-1, and 1,510 to 1,574 cm-1 was weaker in stages 1 and 2 compared with later stages, whereas for the regions 2,984 to 3,077 cm-1 and 3,081 to 3,133 cm-1 the effect of pregnancy was greater for stage 1 compared with other stages. Despite our conclusion that milk FT-MIR data poorly diagnose PS, our study provides new insights into spectral regions that are strongly associated with PS and warrant greater attention.

Cattle farmer psychosocial profiles and their association with control strategies for bovine viral diarrhea

Bovine viral diarrhea (BVD) is endemic in the United Kingdom and causes major economic losses. Control is largely voluntary for individual farmers and is likely to be influenced by psychosocial factors, such as altruism, trust, and psychological proximity (feeling close) to relevant “others,” such as farmers, veterinarians, the government, and their cows. These psychosocial factors (factors with both psychological and social aspects) are important determinants of how people make decisions related to their own health, many of which have not been studied in the context of infectious disease control by farmers. Farmer psychosocial profiles were investigated using multiple validated measures in an observational survey of 475 UK cattle farmers using the capability, opportunity, motivation-behavior (COM-B) framework. Farmers were clustered by their BVD control practices using latent class analysis. Farmers were split into 5 BVD control behavior classes, which were tested for associations with the psychosocial and COM-B factors using multinomial logistic regression, with doing nothing as the baseline class. Farmers who were controlling disease both for themselves and others were more likely to do something to control BVD (e.g., test, vaccinate). Farmers who did not trust other farmers, had high psychological capability (knowledge and understanding of how to control disease), and had high physical opportunity (time and money to control disease) were more likely to have a closed, separate herd and test. Farmers who did not trust other farmers were also more likely to undertake many prevention strategies with an open herd. Farmers with high automatic motivation (habits and emotions) and reflective motivation (decisions and goals) were more likely to vaccinate and test, alone or in combination with other controls. Farmers with high psychological proximity (feeling of closeness) to their veterinarian were more likely to undertake many prevention strategies in an open herd. Farmers with high psychological proximity to dairy farmers and low psychological proximity to beef farmers were more likely to keep their herd closed and separate and test or vaccinate and test. Farmers who had a lot of trust in other farmers and invested in them, rather than keeping everything for themselves, were more likely to be careful introducing new stock and test. In conclusion, farmer psychosocial factors were associated with strategies for BVD control in UK cattle farmers. Psychological proximity to veterinarians was a novel factor associated with proactive BVD control and was more important than the more extensively investigated trust. These findings highlight the importance of a close veterinarian-farmer relationship and are important for promoting effective BVD control by farmers, which has implications for successful nationwide BVD control and eradication schemes.

Assessment of statewide and within-herd seroprevalence of Anaplasma marginale antibodies in 12 Bos taurus–Bos indicus cow herds and the association with sporadic outbreaks of bovine anaplasmosis in Florida

Our objective was to assess within-herd seroprevalence of Anaplasma marginale antibodies across 12 Florida beef cattle herds and compare with statewide seroprevalence. Twelve surveyed herds ranged in size from 160 to 456 adult Bos taurus – Bos indicus cattle. Statewide A. marginale seroprevalence relied on blood samples obtained at slaughter from 201 Florida cattle. Screening relied on competitive ELISA. Before serology, an outbreak of anaplasmosis resulted in increased mortality (up to 17.8%) and abortions in several herds. Up to 29.2% of cows aborted late in gestation in 2 herds that included many cattle introduced from Texas. Among 1,085 cattle tested in the 12 herds, seroprevalence of A. marginale varied from 2.6 to 85%, with an overall seropositive rate of 50.3%. Cattle in open herds were 6.23 (95% CI: 4.26–9.17) times more likely to experience mortality and 3.10 (95% CI: 2.39–3.98) times more likely to abort than animals in closed herds. Average mortality (12%) and abortion (16.3%) among open herds were significantly ( P < 0.05) higher than mortality (1.9%) and abortion (5.3%) among closed herds. Overall seropositivity among affected herds was higher than the apparent statewide seroprevalence of 20.32%. This survey provides estimates of seropositivity among Florida cattle and reports the absence of uniform herd immunity in an area considered endemic for bovine anaplasmosis. These data highlight unrestricted cattle movement and environmental conditions that favor vector-borne disease transmission as risk factors for disease outbreaks even in regions that are considered endemic for bovine anaplasmosis.

Bovine Viral Diarrhea Virus within and herd prevalence on pasture-based dairy systems, in southern Chile dairy farms

Bovine Viral Diarrhea (BVD) is a ubiquitous endemic disease in most bovine populations that causes a negative economic impact on cattle production systems. However, true herd and individual prevalence in Chile have not been estimated based on statistical and epidemiological considerations and uncertainty regarding the infection's extension at animal and herd levels. In addition, the risk factors that can influence how the infection has spread among the cattle premises have not been assessed yet. Therefore, the study aimed to estimate true herd and animal prevalence of active BVDV infection in pasture-based dairy herds and to evaluate risk factors potentially associated with the status of herds and the within-herd prevalence, using a Bayesian approach.A cross-sectional study was performed over a random stratified (proportional to herd size) sample of one-hundred and fifty dairy herds selected in Chile's two leading dairy regions (Region de Los Ríos and Region de Los Lagos). We obtained 12.311 blood samples from lactating cows, but 4.998 randomly selected samples were processed due to budget constraints. For estimating BVDV Herd Prevalence (HP), a herd was considered infected if at least one positive animal to Ag-ELISA was found. In addition, a survey was completed on each farm, aiming to collect information to assess the influence of some variables over the state of the herds; both estimations were obtained using a Bayesian approach.True herd prevalence and true individual prevalence of BVDV active infection were estimated at 77 % and 3.5 % respectively, no significant differences were found between characteristics like herd size, location, vaccination, etc. Open herds and herds that mix herd categories are more likely to have higher BVDV prevalence.

Visual identification of individual Holstein-Friesian cattle via deep metric learning

Holstein-Friesian cattle exhibit individually-characteristic black and white coat patterns visually akin to those arising from Turing’s reaction-diffusion systems. This work takes advantage of these natural markings in order to automate visual detection and biometric identification of individual Holstein-Friesians via convolutional neural networks and deep metric learning techniques. Existing approaches rely on markings, tags or wearables with a variety of maintenance requirements, whereas we present a totally hands-off method for the automated detection, localisation, and identification of individual animals from overhead imaging in an open herd setting, i.e. where new additions to the herd are identified without re-training. We find that deep metric learning systems show strong performance even when many cattle unseen during system training are to be identified and re-identified – achieving 93.8% accuracy when trained on just half of the population. This work paves the way for facilitating the non-intrusive monitoring of cattle applicable to precision farming and surveillance for automated productivity, health and welfare monitoring, and to veterinary research such as behavioural analysis, disease outbreak tracing, and more. Key parts of the source code, network weights and underpinning datasets are available publicly (OpenCows2020).

English

Contagious caprine pleuropneumonia (CCPP) is an economically important and potentially fatal disease of small ruminants caused by Mycoplasma capricolum subsp. capripneumoniae (Mccp). We designed this cross-sectional study to investigate the seroepidemiology of CCPP in the small ruminants of Oman. For this purpose, we sampled a total of 4015 small ruminants (2119 goats and 1896 sheep) from 510 flocks belonging to different governorates of Oman. A commercial competitive enzyme-linked immune-sorbent assay (cELISA) was used to test the samples. Prevalence (%) along with 95% confidence intervals (CI) was calculated, and a univariable analysis was conducted to screen different risk factors. Furthermore, a binary logistic regression model was built at the animal and flocklevel (Table 3). In total, 147 (28.8%, CI 24.9, 33.0) flocks tested positive for the CCPP and the seroprevalence ranged from 10.0 to 53.8% in various governorates (p = 0.001). The prevalence was significantly (P&lt;0.001) high in goats (28%, CI 23.8, 32.5) as compared to sheep (13.1%, CI 24.9, 33.0). At flock level; the open herds (OR 2.08, 1.33, 3.27), having a location in the coastal regions (OR 1.70, 1.14, 2.53) and flock size of more than 100 animals (OR 2.45, 1.54, 3.91) were the significant risk factors for CCPP in Oman. At the animal level; goats (OR 2.87, CI 2.17, 3.81), and small ruminants above the age of one year (OR 2.23, CI 1.38-3.59) were found more likely to acquire CCPP. We suggest that a control program based on the changes in the management system to minimize the risk factors and a possible mass vaccination should be devised to check CCPP in Oman.

Seroepidemiological prevalence of Leptospira spp. in dairy cattle herds of the Doge River region in the State of Espírito Santo

The objective of this study was to investigate the prevalence and risk factors of Leptospirosis in dairy herds of the Rio Doce, ES, composed of six municipalities: Aracruz, Ibiraçu, João Neiva, Linhares, Rio Bananal and Sooretama. The properties were randomly selected, with two properties per municipality. It was admitted as a criterion for selecting these properties because they did not present the management of anti-Leptospira vaccination in the animals. The number of blood samples in each property was according to the availability of animals, which totaled 100 blood samples. The serological technique used was Microscopic Soroagglutination (SAM). Serum samples were submitted to dilutions of 10 (ten) live antigens, including the serovars L. australis, L. butembo, L. copenhageni, L. bratislava, L. canicola, L. grippothyphosa, L. hardjo prajitno, L. L. pomol, L. icterohaemorrhagiae, L. Wolffi of the genus Leptospira spp. of the species interrogans.The prevalence of serovars in this study was from Wolffi (24%); Bratislava (15%); Hardjo prajitno (11%); Pomona (10%); Butembo (10%); Australis (8%); Canicola (5%); Ichterohaemorragiae (5%); Grippotyphosa (4%); Copenhageni (3%). The results demonstrate that bovine Leptospirosis is present in the mesoregion with 50% prevalence in individuals, the main risk factors being non-vaccination, presence of rodents, joint breeding and open herd.

Evaluation of Assamese buffaloes considering important economic traits under field conditions in their home tracts

The Assamese buffaloes are being reared by the farmers/breeders for milk, meat and for draught purposes. These buffaloes are known for higher fat contents in their milk (8.5 percent on an average) and are famous in the market with a great demand and are known as “Khuti milk”. They are good source of livelihood for breeders and the graziers both in its breeding tract and have attracted researchers to consider the study of some important economic traits under field conditions. The present study was organized and considered the data on a total of 324 Assamese buffaloes distributed over three districts namely Kamrup, Nagaon and Darrang in Assam covering 35 khutis (open herds) during the year 2015-16 eighteen months. The lactation milk yield of Assamese buffalo was observed as 448.38±1.67 kg with a lactation length of 237.06±0.74 days and the peak yield and days to attain were measured as 3.41±0.02 kg and 54.16±0.19 days respectively. The reproduction traits like age at first calving, gestation period, service period and inter-calving period were considered for the study based on the breeders’ interview using pre-structured formats. The age at first calving was recorded as 52.28±0.81 months, the gestation period was observed as 323.10±0.68 days with an inter-calving period of 465.70±1.67 day. The service period and the dry period for these buffalo was 171.34±0.82 and 252.84±1.47 days respectively. The production and reproduction performance of Assamese buffaloes need special attention to be addressed for further improvements to help a large size of population of Assam, who are entirely depending for their livelihood on these valuable AnGR (buffaloes) of Assam.

Quantification by simulation of the effect of herd management practices and cow fertility on the reproductive and economic performance of Holstein dairy herds

The performance of dairy herds is affected mainly by factors related to cows' characteristics and herd management practices. However, these factors are interrelated, and as such, the estimation of their individual effect on the performance of dairy herds remains difficult. The aim of this study was to estimate the weight of these factors as well the interactions between them on the reproductive and economic performance of dairy farms. A stochastic dynamic model was used to simulate most physiological and management processes occurring on a dairy farm. A herd of 60 Holstein cows, with a milk yield of 8,000L/cow-year, representative of French Holstein dairy herds, was simulated. A total of 216 scenarios were run by combining 2 levels of postpartum cyclicity resumption (average: 45d, high: 75d), 3 levels of 21-d conception rate of the herd (i.e., proportion of cows pregnant 21 d after insemination; low: 25%, average: 45%, high: 70%), 3 levels of probability of pregnancy loss until 120 d (low: 3%, average: 15%, high: 43%), 3 levels of sensitivity of estrus detection by the farmer (low: 20%, average: 50%, high: 90%), 2 alternative managerial goals (constant number of cows or constant volume of milk sold), and 2 types of management for the sale and purchase of animals (closed or open herd). The effect of each factor was estimated by sensitivity analysis. The parameter that had the greatest effect on reproductive performance was the sensitivity of estrus detection: a 10-percentage-point increase between the low and average levels and between the average and high levels reduced the calving interval by 16and 5.7d, respectively. However, the factor that had the greatest effect on economic performance was the 21-d conception rate: a 10-percentage-point increase between the low and average levels and between the average and high levels increased the gross margin by €62.2 and €22.3/cow-year, respectively. The pregnancy loss until 120 d had an effect on economic performance: an increase of 1 percentage point of this parameter decreased the gross margin by €2/cow-year. The other factors studied, and their interactions, did not have a major effect (low value of sensitivity indices). Closed herds or farms with a constant number of cows had economic losses of €58/cow-year compared with open herds or to farms with constant volume of milk sold. Altogether, our data suggest that, in a typical French dairy farm, farmers' efforts on estrus detection will be more profitable when associated with improvement of the conception rate of the cows.

Biosecurity and herd health management practices on Canadian dairy farms

The Canadian dairy industry has created national standards to support the adoption of biosecurity practices and to reduce disease risks across the country. There is, however, very little information on the adoption of these practices. The present study aimed to describe the adoption of biosecurity practices on Canadian dairy farms shortly after the creation of the national standards and to identify demographic factors associated with practice adoption. In 2015, 2 questionnaires (phase 1 and 2) were administered to Canadian dairy farmers during an extensive cross-sectional study. Associations between adoption of biosecurity practices as well as associations between adoption of these practices and demographic variables were tested using multiple correspondence analysis. A total of 1,157 questionnaires were completed in phase 1, and a subsample of 368 respondents was selected using stratified random sampling to complete phase 2 during visits to the farms. There was a lack of investigation into general disease syndromes such as a high prevalence of abortion or an unexplained death (38 and 22% of respondents, respectively). Biosecurity measures within herds and between herds to minimize the spread of infection were not widely adopted (e.g., 27% of the respondents never housed sick or lame animals in their calving pen, 41% had closed herds, and 25 and 48% of the open herds had no strategy for introducing new additions and reintroducing returning animals, respectively). Cleanliness of the cows before calving was always ensured by 29% of the respondents, and 27% of the respondents reported always sanitizing the calving pen after each calving. Less than 15% of the respondents had measures in place to limit or control visitors coming on their farm. Moreover, less than half of the respondents reported requiring family members, employees, and visitors to wear farm-designated or clean boots and coveralls. From the multiple correspondence analysis, 2 dimensions were retained and were summarized as "animal movement, calving area, and visitor biosecurity" and "employee biosecurity." Geographical region, type of housing, and milk production were associated with the "employee biosecurity" dimension. The present study demonstrates that many important biosecurity practices are not implemented on Canadian dairy farms; therefore, efforts to promote the adoption of these practices will be necessary to improve biosecurity in dairy herds.

Occurrence of Bovine Viral Diarrhea (BVDV) and Bovine Infectious Rhinotracheitis (IBR) Virus Infections in Buffaloes in Pernambuco state - Brazil

Background: Buffaloes are susceptible to viral infections, often associated with pathologies of importance in cattle breeding. Among the numerous infectious diseases, Bovine Viral Diarrhea (BVDV) and Bovine Infectious Rhinotracheitis (IBR) have a negative impact on buffalo creations. This study aimed to detect the occurrence of bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis (IBR) virus infections in buffaloes in Pernambuco state, Brazil.Materials, Methods &amp; Results: For this purpose, serum samples were obtained from 244 buffaloes on eight properties distributed in six municipalities. The search for anti-BVDV and -bovine herpesvirus type-1 (BoHV-1) antibodies was performed using the virus neutralization technique. To analyze the association between the serological status of BoHV-1 infection and aspects of hygienic-sanitary and reproductive management, an investigative questionnaire with objective questions was used. In total, 97.9% (239/244) of buffaloes had anti-BVDV antibodies and 56.1% (137/244) had anti-BoHV-1 antibodies. Co-infection was observed in 55.3% (135/244) of buffaloes. The distribution of antibody occurrence in buffaloes by properties ranged from 90.5% to 100.0% for BVDV and from 4.8% to 100% for BoHV-1. It was not possible to perform an association analysis for BVDV infection; however, in that for BoHV-1 infection, the following variables exhibited a significant association: an extensive breeding system (P &lt; 0.001), open herd (P = 0.029), lack of reproductive rest (P = 0.029), natural mating in females with reproductive disorders (P &lt; 0.001), exploration type (P = 0.0014), presence of wild animals (P &lt; 0.001), and lack of cleaning facilities (P = 0.008).Discussion: The occurrence of anti-BVDV antibodies in this study was 97.9% this was higher than those reported in other country’s regions. The results of the present study demonstrate a high occurrence of anti-BVDV antibodies in each of the properties in Pernambuco state, demonstrating that the animals have contact with infection sources, due to the large number of positive animals. Indeed, it is likely that there is at least one PI animal in every herd. It was observed that 100% of the properties possessed at least one positive animal. The high number of positive animal properties may be related to the absence of biosecurity measures; a subclinical BVDV infection can occur which the owners cannot identify it, as it is not common the adoption of a reproductive program in the region. The occurrence of the anti-BoHV-1 antibody in this study was 56.1%. In other states, both lower and higher prevalences were reported compared to this study. The high number of properties with positive animals may be related to several factors, including the ability of the virus to remain latent, thus introducing a single animal infected with BoHV-1 sufficient for infection spread and perpetuation in buffaloes. It is believed that the introduction of infected animals and the lack of disease knowledge by the producers may have been responsible for the agent’s introduction and maintenance in the herds. In conclusion, BVDV and IBR virus infections occur in buffaloes in Pernambuco state. Thus, it is suggested that prophylactic measures, including routine diagnosis, reproductive animal control, and strict health care, such as employing cleaning facilities, avoiding contact with neighboring herds, acquiring animals with a negative diagnosis and using an artificial insemination program should be implemented at each property to reduce the reproductive losses caused by these infections.

Bovine Respiratory Disease (BRD) Complex as a Signal for Bovine Viral Diarrhea Virus (BVDV) Presence in the Herd

Background: Infections are caused by Bovine Viral Diarrhea Virus and still continue to be a worldwide plague in cattle industry. It is responsible for sudden death syndromes in adult cattle with high mortality rates, abortions, acute gastrointestinal and respiratory diseases. The BVDV infection occurs in early pregnancy (40-142 days), in immunosuppressed females or cows results in 100% of persistently infected (PI) calves that are seronegative and asymptomatic at birth. Evidences suggests that BVDV contributes to BRD complex potentiating secondary infections caused by Mannheimia haemolytica e Pasteurella multocida due to its immunosuppressive action. However, the farmers have often associated the respiratory syndrome with other infectious agents. This paper reports the attendance of dairy calves manifesting clinical signs of bronchopneumonia, which led to the screening of the persistently infected animals to control of the BVDV infection in the herd.Materials, Methods &amp; Results: During the technical assistance, ten calves manifesting bronchopneumonia were selected to trans-tracheal lavage (TL) in order to identify possible infectious agents. Reverse transcription polymerase chain reaction (RT-PCR) detected the presence of BVDV in two heifers. Pasteurella multocida was the unique bacterial agent isolated from TL (5/10, 50%). These data motivated the technical team and producers to investigate the PI screening by direct enzyme-linked immunosorbent assay from biopsies of the ear edge. The screening of PI’s detected 29 positive within of 2,342 animals tested (1.23%). The re-test of positive was performed only in 24 animals due to the cull of five bovine with severe bronchopneumonia and diarrhea, confirming 18 persistently infected calves (18/24; 75%). Finally, in all PI’s live dams were tested. It was observed four positive adult animals. One grand dam was live and tested, but it had negative result for direct enzyme-linked immunosorbent test. The rate of PI’s considering the whole herd was 0.81% (22/3,700 animals).Discussion: The involvement of BVDV in the etiology of bronchopneumonia was confirmed by detection of the virus in trans-tracheal lavages in two calves by RT-PCR. The susceptibility for Pasteurella multocida infection could be promoted by BVDV prime-infection, considering that immunossupressive nature of BVDV is a critical factor in the interaction with others viruses and bacteria. At this time, we are aware about any report about the detection of BVDV in trans-tracheal lavages. These findings culminated with the screening of PI animals in the herd, detecting rates of 0.81%. The intensive vaccination and colostrum management of this farm could protected the herd against BVDV, however others facts facilitated the introduction of the virus in the herd. This research was conduced in a high-production dairy farm with around 3,700 animals raised in an open herd, in which some of cows with high genetic potential were transferred for embryo collection in the state of Paraná, Brazil; resulting in the addition of the calves to the herd by others routes. Moreover, the farm used for many years vaccine containing only BVDV-1, which may have favored the entry and spread of BVDV-2 or BVDV-3 in the herd. This research showed the presence of BVDV in trans-tracheal lavage of heifers with bronchopneumonia by RT-PCR. This fact points to the need of BRD control programs that include detection of PI animals.

Virus neutralization technique as a tool to evaluate the virological profile for bovine viral diarrhea virus infection in dairy water buffalo (Bubalus bubalis) herds.

Serological evidence shows that the bovine viral diarrhea virus (BVDV) infections are present in Brazilian dairy and beef water buffalo herds. As few reports describe the BVDV infection profile the aim of this study was to evaluate the dynamics of BVDV circulation in Brazilian dairy water buffalo herds through analysis of the seropositivity rate and the titer range of anti-BVDV neutralizing antibodies in a group of animals that are considered sentinels. Blood samples (n = 305) were obtained from unvaccinated, asymptomatic young water buffalos from four dairy herds randomly identified as A (n = 106), B (n = 62), C (n = 119), and D (n = 18). The detection and titration of anti-BVDV neutralizing antibodies were evaluated by the virus neutralization test according to the World Organization for Animal Health. Analysis of the results revealed two distinct epidemiological conditions. The first is represented by herds A and C where high rates of seropositive animals (A = 39.6%; C = 51.3%) and high and very variable antibodies titers suggested active BVDV infection. The other condition is represented by herds B and D with low rates of seropositive animals (B = 8.1%; D = 11.1%) and low and little variable antibodies titers suggesting an epidemiological condition of infection stability. Some variables were observed in herds with a distinct BVDV infection profile. Herds with active infection were big, open herds, and had more management practices. In contrast, the herds with infection stability were small, closed herds with few management practices. These results highlight the importance of evaluation, monitoring, and control of BVDV infection also in dairy water buffalo herds.

Utility, Morphometrical characteristics of Assamese buffalo and Socio-economic status of the breeders in its home tract

Present study was conducted through systematic survey of 18 villages in three districts (Kamrup, Nagaon and Darang) of Asom, India, using stratified random sampling technique. Total 52 Khutis (open herds) having 3310 buffaloes of different age and sex under farmers management, were purposively selected for utility and morphometrical studies of the breed and socio-economic status of the breeders in its home tract. The morphometrical traits, viz. Length of forehead ranged 23.81±0.70 to 48.42±0.94cm, neck length (22.91±0.66 to 39.82±1.02 cm), horn length (8.00±0.25 to 67.10±0.64 cm), space between two horns at base (9.14±0.24 to 18.52±0.64 cm) and tips (18.12±0.24 to 43.43±0.75 cm), tail length (44.60±0.45 to 80.60±0.85cm), and length of switch of the tail (8.09±0.20 to 15.89±0.20cm) were observed for the animals of both the sexes belonging to the age groups of up to 6 months, 6-12 m, 1-2 year, 2-3 years, 3-4 years and 4 years and above. The study shows that the animals are being utilized for milk only (82.69%) and milk and meat (17.31%). It was also found that 40.38% breeders are receiving an income ranges from Rs 50,000 to 75,000 and 28.85% breeders getting more in between 75,000 to 1,00,000 per year out of these animals, besides age, education level, land holding, family size and number of paid graziers were also studied. The Assamese buffalo breed is a very good source of livelihood for tribals, nomads and poor farmers, hence immediate steps should be taken to save this valuable breed in its natural habitat.