Herd Management Research Articles

Predicting dairy herd resilience on farms with conventional milking systems.

This research paper addresses the problem that, thus far, there is no method available to predict herd resilience for farms that do not use automated milking systems (AMS). Recently, a methodology was developed to estimate both individual cow as well as herd resilience using daily milk yield observations at individual cow level from farms with AMS. This AMS-based method, however, is not suitable on farms that use conventional milking systems (CMS) where such individual cow milk yield observations are lacking. Therefore, this research aimed at predicting herd resilience using herd performance data that is commonly available on CMS farms. To do so, data consisting of 585 Dutch AMS farms where herd resilience estimates using the AMS-based method were available was examined. To predict herd resilience with herd performance data, only those data that are also commonly available on CMS farms were used in a 5-fold cross validation Random Forest model. These herd resilience estimates were subsequently compared with the AMS-based herd resilience estimates. Results showed that it is possible to predict with a 69.9% probability whether a herd performs with above or below average herd resilience using only variables available on CMS farms. Especially, the proportion of cows with an indication of rumen acidosis, proportion of cows with an elevated somatic cell count and the fluctuation in herd size over the years are good predictors of herd resilience. Since herd management decisions appear to affect herd resilience, a lower predicted herd resilience could be taken as a general indication that tactical or strategic management changes could be taken to improve the herd resilience.

Associations of cow- and herd-level factors during the dry period with indicators of udder health in early-lactation cows milked by automated milking systems

This observational study aimed to determine the association of cow-level factors and herd-level housing and management practices during the dry period with indicators of udder health in early-lactation cows in automated milking system (AMS) herds. Data were collected from 166 commercial AMS dairy farms (mean ± standard deviation = 116 ± 111 milking cows; range = 39 to 1,200) across Canada between October 2018 and September 2020. Information on herd demographics, housing, and management practices was obtained on each farm using 2 surveys. On each farm, we selected all cows that had available Dairy Herd Improvement (DHI) somatic cell count (SCC) data for their last milk test before dry-off (>250 d in milk) and their first milk test after calving (5-45 d in milk). Data from 14,007 cows were included after excluding cows with a dry period of <30 d and >120 d. Using the SCC data, we calculated for each cow the somatic cell score (SCS) for the last milk test before dry-off (PreSCS) and the first milk test after calving (PostSCS), which we then averaged per herd at a test-day level. Intramammary infection (IMI) was estimated using cow SCC data. Each cow was classified as not infected (SCC <200,000 cells/mL) or infected (SCC ≥200,000 cells/mL) at her last milk test before dry-off and her first milk test after calving. Based on this classification, cows were further categorized as never infected, always infected, new IMI, or cured IMI. At the cow level, a higher PostSCS was associated with longer dry periods. The odds of having a new IMI were higher for cows of higher parity and that had lower 305-d milk yield before dry-off. Cows with lower parity were more likely to cure an IMI. At the herd level, a higher 305-d milk yield before dry-off was associated with a lower incidence of new IMI and a higher incidence of cured IMI. Separating cows into a different pen as preparation for dry-off tended to be associated with a lower PostSCS and incidence of new IMI. At dry-off, herds that used teat sealants and blanket antibiotic dry cow therapy also had lower PostSCS. During the dry period, housing cows in different groups was associated with a higher PostSCS and a lower incidence of cured IMI, while housing cows in both pack pens and stalls compared with only pack pens was associated with a lower incidence of new IMI. Finally, placing cows onto the AMS to be milked one or more days after calving tended to be associated with a lower PostSCS compared with placing them in the AMS within the first day postpartum. In summary, indicators of udder health in early-lactation cows in AMS herds were associated with several cow-level factors and herd-level housing and management practices before dry-off, at dry-off, during the dry period, and at the beginning of lactation. Thus, if some of the associations identified are causal, AMS producers may be able to improve udder health through modifications of housing and management practices.

Assessing and explaining trends in dairy cattle herd performance variables while using three-breed rotational crossbreeding: empirical evidence from commercial farms

Three-breed rotational crossbreeding can improve the functional traits of dairy cows, but few farmers in most Western countries use it. This could be due to a lack of knowledge of its medium- and long-term effects on animal performance at the herd level, regardless of the initial states of the farm and herd, the crossbreeding programme(s) used and changes in farm management and structure while transitioning to it. We aimed at assessing changes in animal performance of dairy cattle herds transitioning towards three-breed rotational crossbreeding and at identifying factors that explained them. We sampled 13 French dairy cattle farms for which animal performance data were available for a 9-year period (2009–2017) and described their trends in herd management and the farming system when introducing crossbreeding. We calculated five herd performance variables: mean milk productivity per cow-year (MilkCow), mean Milk solids content (FatProtCont), and the percentages in the herd of cows with no more than 117 days open (FertileCow), with mean somatic cell score less than 4 over the lactation period (HealthyLact) and with four lactations or more (L4+). We defined 15 variables related to herd and farm structure and management. We applied linear regression to each variable over the study period and used the intercept and slope to describe their initial values in 2009 and their trends, respectively. We performed partial least squares (PLS) regression to assess relationships between the trends in herd performance variables and potential explanatory variables, including the initial values of herd performance variables and the initial values of and trends in herd and farm structure and management variables. Linear regressions showed that within herds, median MilkCow decreased (–177 kg/cow per year), FertileCow increased (+1.5%/year) and FatProtCont either remained stable or increased (+0.1 g/kg per cow). Conversely, changes were less distinct for HealthyLact and L4+. From 2009 to 2017, herd size increased in most farms (med = +1.2 LU/year). The PLS regression highlighted that herds in which MilkCow decreased the most over time were those in which HealthyLact and L4+ decreased and increased the most, respectively. Moreover, for herds in which FertileCow increased the most, FatProtCont either decreased, or increased less. Based on association scores from the PLS, changes in the genetic composition of the herd influenced changes in herd performance variables more than did changes in overall farm management (|0.28|–|0.59| vs |0.26|–|0.50|). Our findings suggest that dairy crossbreeding is relevant to rebalance herd performance between production and functional traits.

Alternative Samples for Porcine Reproductive and Respiratory Syndrome Surveillance in an Endemic PRRSV-1-Infected Breeding Herd: A Descriptive Study.

Knowing porcine reproductive and respiratory syndrome (PRRS) status is essential for designing herd management protocols. For this, weaning-age pigs are a key subpopulation. Recently, different alternatives to blood sampling have been introduced because they are easier, welfare-friendly and cost-saving tools. Moreover, most of them allow the testing of more animals and seem to be more sensitive in low-prevalence scenarios. However, these studies were implemented mainly in PRRSV-2-infected herds. The first objective of our study was to compare the rate of detection of PRRSV-1 by RT-qPCR in individual serum samples, family oral fluid samples (FOF) and udder wipes (UW) collected the day before weaning. The second objective was to evaluate the suitability of pooling. The study was performed on a 210-sow farrow-to-finish farm which was PRRSV-1 infected and unstable. A total of 119 litters were sampled. The rate of detection of PRRSV-1 in blood samples, FOF and UW was 10.9%, 7.6% and 0.8%, respectively. The agreement between sera and FOF was almost perfect even if the detection capacity of sera was numerically superior to FOF. The Ct values of positive sera were statistically lower than those of FOF. Two modalities of pooling (1:3 and 1:5) were tested for sera and FOF. For sera, both modalities did not impact the PRRSV-1 status either at the litter level or at the batch one. On the other hand, whatever the modality (pooled by 3 or 5), most of the pools of FOF gave negative results, misclassifying many litters and batches.

Usefulness of the total and differential somatic cell count based udder health group concept for evaluating herd management practices and udder health in dairy herds.

Subclinical mastitis and associated economic losses are a steady challenge in the dairy industry. The combination of the well-established somatic cell count (SCC) parameter and the new differential SCC (DSCC) opens up the possibility to categorise cows into four different udder health groups (UHG) based on results from a single milk recording/dairy herd improvement (DHI) test: UHG A: healthy/normal, ≤200,000 cells/mL and DSCC ≤65 %; B: suspicious, ≤200,000 cells/mL and DSCC >65 %; C: (subclinical) mastitis, >200,000 cells/mL and DSCC >65 %; D: chronic/persistent mastitis, >200,000 cells/mL and DSCC ≤65 %. The objectives of this study were to investigate 1) herd management practises among herds in different UHG categories and 2) herd performance parameters depending on the proportion of cows in UHG A. A total number of 41 herds in Styria, Austria, and Thuringia, Germany, were visited and interviewed for the first part of the study. The herds were categorised into 3 UHG categories depending on the proportion of cows in UHG A: I =>65 %; II =55-65 %; and III =<55 %. Those with good udder health and best herd performance (+9 % milk yields, +11 % longevity, -35 % antibiotic treatments) applied distinct preventive measures, in particular excellent cubicle management and early antibiotic treatment (P<0.05 each). However, preventive measures were applied to a lower extent in other herds. Herds were categorised differently using the UHG concept compared to SCC alone as the UHG-based categorisation allowed to clearer distinguish herds with medium-good from those with good udder health. A total number of 129,812 regular milk recording/DHI test day results of 890 Austrian and 183 German herds was used for the second part of the study. Results revealed a trend of increasing daily production as proportions of cows in UHG A increase. In conclusion, the UHG concept allowed clearer distinction of herds with good, medium-good, and poor udder health and could be used to promote practises leading to better animal health, less antibiotic treatments, and higher milk quality.

The Association between Socioeconomic Profiles, Attitudes, and Knowledge of Dairy Farmers Regarding Somatic Cell Count and Milk Quality.

The primary objective of this study was to investigate the association between the bulk tank somatic cell count (SCC) and dairy farmers' knowledge about milk quality, mastitis control, and their socioeconomic characteristics. Additionally, we estimated the association between the bulk tank SCC and bulk tank milk hygienic quality in dairy herds. Bulk tank milk samples from 120 dairy herds enrolled in the milk quality payment program were collected for the determination of the SCC, the total bacterial count (TBC), the preliminary incubation count (PIC), the laboratory pasteurization count (PC), and the coliform count (CC). Based on the bulk tank SCC results, 63 herds were selected and categorized into three groups: (a) low SCC: ≤250,000 cells/mL (n = 16); (b) medium SCC: >250,000 ≤ 400,000 cells/mL (n = 24); and (c) high SCC: >400,000 cells/mL (n = 23). Socioeconomic profiles, attitudes, and knowledge of somatic cell count and milk quality were assessed using previously tested questionnaires, which were used to interview the herd managers of the 63 selected dairy herds. Among the findings, 87.0% of the dairy herds had an SCC < 400 × 103 cells/mL, and presented milk production as the main economic activity of the farm, whereas only 47.0% of dairy herds with an SCC > 400 × 103 cells/mL had milk production as the main economic activity of the farm (p < 0.031). In a total of 95% of the selected herds (n = 60), milking machines were used, with pipeline milking machines being more predominant, accounting for 70.8% in herds with a medium somatic cell count (SCC) and 78.3% in herds with a high SCC, as opposed to herds with a low SCC at 50% (p < 0.031). The frequency of dairy producers' awareness of the maximum legal requirements for the bulk tank SCC and TBC was higher in herds with a higher SCC than in herds with a medium SCC. In conclusion, the results of this study indicate a significant association between the bulk tank somatic cell count (SCC) and dairy farmers' knowledge about milk quality, mastitis control, and socioeconomic characteristics. These findings emphasize the importance of knowledge and the socioeconomic profiles of dairy farms in maintaining and enhancing milk quality in dairy herds.

Determination of Structural Characteristics of Large-Scale Dairy Farms: Example of Yozgat Province

This research was carried out to determine the status of dairy cattle farms in Yozgat province, which has significant potential in animal husbandry, to evaluate the positive and negative aspects of the existing barns, and to put forward suggestions for solving the problems. The research was completed by conducting observation and physical measurement studies in 28 dairy cattle farms with more than 50 milking animals, which we classified as large-scale, with the data obtained through questionnaires. Most dairy farms were established in the last ten years and received investment and grant support from various public institutions. It has been observed that the criteria suitable for animal welfare, especially in ventilation and building materials, are not followed by avoiding investment costs in farms established with equity capital. In the dairy farms established by receiving grants and investment support, it was observed that the stables were built in conditions suitable for animal welfare. Still, the herd management system was not established, and the records were not kept healthy because the farm owners and employees of the farms were insufficient in dairy cattle breeding knowledge, which would increase the costs. Although the majority of the examined enterprises did not have structural and technical problems, the absence of a birth partition in 21.43%, an individual calf pen in 25%, a ventilation shaft in 3.57%, and a manure pit slope in 28.57% was seen as an obstacle for these dairy farms to be modern enterprises. It is recommended that the economic sustainability of dairy cattle farms, which is a long-term investment branch, does not only depend on having sufficient equipment in terms of structural features but also on farm owners and employees should have sufficient knowledge and infrastructure on dairy cattle breeding and training should be provided to the relevant people.

Assessment of Herd, Calf, and Colostrum Management Practices on Austrian Dairy Farms Using a Scoring System.

The objectives of the study were to describe colostrum management on Austrian dairy farms and to explore differences between regions (alpine/flatlands), organic and conventional producing farms, and full-time or part-time operated farms. An online survey (24 questions) on general farm characteristics and herd and calf management was sent to 16,246 farmers. In total, 2328 farmers (response rate 14.3%) answered the questionnaire. To allow an objective comparison, a scoring system was implemented. Farm size is, on average, smaller in the alpine regions than in the foothills/flatlands regions of Austria. Small farms were more often organic-producing farms (81.6%) and operated part-time (93.8%). In foothills/flatland regions, 70.0% of farms have a separate calving area, and in the alpine regions, it is solely 42.8%. Colostrum testing is still mostly done by visual appraisal (63.7%); only a few farmers use a colostrometer (8.8%), brix-refractometer (18.3%), or ColostroCheck® (9.2%, a cone-shaped device to rate the flow velocity of colostrum). The results of the present study using the scoring system showed differences in herd and calf management practices in all sectors. In the future, the findings and especially the scoring system can support Austrian dairy farmers or veterinarians to better assess areas of improvement on farms in order to prevent calves from suffering from Failure of Transfer of Passive Immunity.

Assessment of Camel Owners’ Knowledge and Practical Behaviors and its Implication on Environmental Sustainability

This study aimed to assess camel owners’ knowledge and practical behavior (KPB) in Saudi Arabia (KSA) and their implications on environmental sustainability. The study depended mainly on primary data. An online questionnaire survey was used to collect data from 267 respondents, in 2022. Descriptive and analytical techniques were used to achieve the stated objectives. Results revealed that, the majority of camels’ owners (91.7%) have low cumulative KPB, which was evident in their traditional practice and non-commercial methods in herd management. Moreover, large numbers of breeders do not sell their milk production due to their traditions, thus, about 23% of them gained no profits. Results also showed that, about 85% of owners were located in the lower level of using cost items (modern technology and labor training), accordingly, 96.6% fall within the low level of profit category. Likewise, about 75% of camels’ owners’ grazing behavior were located in the lower and medium level groups. Furthermore, the cumulative (KPB) effect of age, educational level, main job, training levels, cost of production and grazing behavior were found to be statistically significant in explaining CKPB variations of camels’ owners in KSA. The R-2 indicated that 59% of the variations in the dependent variable was explained by the variations of the independent variables. The also revealed the presence of high degree of positive association between camels’ owners’ CKPB and environmental sustainability. This study stresses on the importance of execution of sound agricultural extension programs and veterinary campaigns to improve camels’ owners’ CKPB. &#x0D; Key words: Camel Raising, Environmental Sustainability, Grazing Behavior, Knowledge and Practical Behavior, KSA.

Estimation of the performance of two real-time polymerase chain reaction assays for detection of Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus dysgalactiae in pooled milk samples in a field study

The early detection of major mastitis pathogens is crucial for the udder health management of dairy herds. Testing of pooled milk samples, either individual test-day cow samples (TDCSs) or aseptically collected pre-milk quarter samples (PMQSs) may provide an easy to use and cost-effective group level screening tool. Therefore, the aim of this study was (1) to evaluate the sensitivity (Se) and specificity (Sp) of 2 commercial multiplex real-time PCR test kits applied to pooled milk samples using a Bayesian latent class analysis and (2) to estimate the probability of detection in relation to the pool size and the number of cows positively tested by BC within a pool. Pools of 10, 20 and 50 cows were assembled from 1,912 test-day samples and 7,336 PMQSs collected from a total of 2,045 cows from 2 commercial dairy farms. Two commercial quantitative real-time PCR kits were applied to detect Staphylococcus (Staph.) aureus, Streptococcus (Strep.) agalactiae and Strep. dysgalactiae in the pooled samples, and a bacteriological culture (BC) was applied to PMQSs yielding a cumulative pool result. A pool was considered BC-positive if it contained at least one BC-positive PMQS. Pathogens were more frequently detected in the PMQS pools than in the TDCS pools. Pools of 10 cows showed the highest probability of detection irrespective of sample type or type of PCR kit compared with larger pool sizes. Estimation with a Bayesian latent class analysis resulted in a median Se in PMQS pools of 10 cows for S. aureus of 63.3% for PCR kit I, 78.1% for PCR kit II and 95.5% for BC; the Sp values were 97.0, 97.6% and 89.1%, respectively. The estimated median Se for Strep. species for PCR kits ranged between 77.5 and 85.6% and for BC between 73.7 and 79.2%; the median Sp values ranged between 93.6 and 99.2% for PCR kits, and between 96.9 and 97.4% for BC. In addition, the probability of detection increased with an increasing number of BC-positive cows per pool. To achieve a probability of detection of 90%, the estimated number of positive cows in PMQS pools of 10 cows for Kit I was 4.1 for Staph. aureus, 1.5 for Strep. agalactiae and 1.3 for Strep. dysgalactiae; for the equivalent TDCS pools and pathogens, 6.9, 1.9 and 2.0 positive cows were required, respectively. For Kit II and PMQS pools, the number of positive cows required was 2.8 for Staph. aureus, 1.4 for Strep. agalactiae and 1.2 for Strep. dysgalactiae; for the equivalent TDCS pools and pathogens, 5.3, 1.8 and 2.0 positive cows were required, respectively. In conclusion, the type of samples used for pooling, the pool size and the number of infected cows per pool determine the probability of detecting an infection with major mastitis pathogens within a pool by PCR testing.

Effect of forage type on swallowed bolus mass and a method for counting swallows in dairy cattle

Dry matter intake (DMI) is a primary determinant of milk production in grazing dairy cows and an ability to measure the DMI of individual cows would allow herd managers to formulate supplementary rations that consider the amount of nutrients ingested from grass. The 2 related aims of this experiment were to define the mean number of swallowed boli and mass of the swallowed boli in Holstein-Friesian dairy cattle offered a variety of forages commonly fed in the dairy industry of southeastern Australia, and to evaluate 2 indirect methods for counting the number of swallows. Twelve ruminally-fistulated, lactating Holstein-Friesian cows were randomly assigned to 3 replicated 4 × 4 Latin square designs and offered 4 forages: fresh chicory (FC), fresh perennial ryegrass (RP), alfalfa hay (AH), and perennial ryegrass silage (RS). The experiment was conducted over 28 d with each of 4 periods consisting of 7 d with 3 d of measurement. Forage diets were offered to individual cows following the partial evacuation of the rumen. The first 20 min after forage was offered constituted the measurement period, during which all swallowed boli were manually captured by samplers who placed their hand through the ruminal fistula and over the cardia entrance of the rumen of each cow. Concurrently, microphones and video cameras were used for the indirect measurement of swallows. The average swallowed bolus mass overall was 17.4 g dry matter (DM) per bolus with the lowest mass observed in cows offered FC (8.9 g DM/bolus), followed by RP (14.9 g DM/bolus), compared with cows offered AH (23.6 g DM/bolus) and RS (22.3 g DM/bolus). The swallowing rate was greater in cows offered FC (78 swallows/20 min) than in cows offered RP, AH, and RS (62.3 swallows/20 min). The audio recording method showed greater concordance (Lin's concordance correlation coefficient = 0.90) with the physical capturing of the boli through the rumen, than the video recording method did (Lin's concordance correlation coefficient = 0.54). It is concluded that the mass of the swallowed boli is related to forage type and that using a microphone attached to the cow's forehead can provide an accurate measure of the number of swallows when verified against the actual number of swallows counted by manual interception of the boli at the rumen cardia.

Effects of prenatal heat stress on birth weight and birth weight genetic parameters in German Holstein calves

The aim of this study was to infer the effects of heat stress (HS) during late gestation of dams on phenotypes and on direct and maternal genetic parameters for birth weight (BiW). We considered 171,221 Holstein calves kept in 56 large-scale co-operator herds. For a clear separation of maternal effects, only calves from dams with at least 3 offspring were included in the analyses. The genotype data set comprised 41,143 SNPs from 1,883 Holstein bulls. Temperature-humidity indices (THI) during the last 8 wk of gestation were calculated in each herd to reflect prenatal HS. A further prenatal HS descriptor was the first principal component (PC1) from principal component analysis considering the daily THI during the last 56 d of gestation. Regression coefficients of BiW on prenatal THI during the last 12 wk of gestation and PC1 were estimated in 13 consecutive phenotypic analyses. The strongest BiW decline was −0.63 kg per standardized THI, identified during 50 to 56 d before birth. A reaction norm model with weekly prenatal THI or PC1 nested within maternal genetic and maternal permanent environmental effects was defined to infer maternal sensitivity in response to prenatal THI alterations. Direct BiW heritabilities were close to 0.33 in the course of prenatal THI. Maternal BiW heritabilities marginally increased from 0.07 to 0.08 with increasing THI. Genetic correlations between maternal genetic effects at maximum HS levels and remaining THI were larger than 0.95, indicating the absence of genotype by time-lagged HS interactions. In contrast, maternal permanent environmental correlations between BiW at prenatal THI indicating HS with BiW at remaining THI substantially declined with increasing THI distances. Hence, from a herd management perspective, avoiding HS during the dry period of the dams will contribute to a slight increase in fetus growth.

Evaluation of the Metabolic Relationship between Cows and Calves by Monitoring Calf Health and Cow Automatic Milking System and Metabolic Parameters.

With this study, we investigated the relationship between a cow's and calf's metabolic state, and its effect on health status. To achieve this, 20 calves of primiparous and 20 calves of multiparous cows were selected. The calves were monitored for 30 days and scored for signs of disease, as described in McQuirk (2008); according to score, they were divided into healthier calves; the Low calf score group (LCS, 5-8), Medium calf score group (MCS, 9-12) and High calf score group (HCS, 14-17); or calves most prone to disease. Their mothers were monitored for the same period with a Lely Astronaut 3 herd management system (Lely, Maassluis, The Netherlands) for rumination time, milk yield, milk fat, protein, lactose concentrations and milk fat to protein ratio. Both cows and calves were sampled for blood, and concentrations of glucose with β-hydroxybutyrate were registered. The results indicate that primiparous cows had a 16% higher blood glucose concentration (3.03 mmol/L SE = 0.093) compared with multiparous cows (2.61 mmol/L, SE = 0.102) (p < 0.01), but no difference in calf glucose was recorded. Β-hydroxybutyrate levels did not differ significantly between cows and calves by parity group. Rumination time was longest in the HCS group at 550.79 min/d. and was 16% longer compared with the LCS group (461.94 min/d.; p < 0.001) and 8% longer compared with the MCS group (505.56 min/d.; p < 0.001). The MCS group rumination time mean was statistically significantly higher compared with the LCS group by 8% (p < 0.001). Milk yield was also highest in the HCS group (44.8 kg/d.): 19% higher compared with the MCS group (36.31 kg/d., p < 0.001) and 13% higher than the LCS group (38.83 kg/d., p < 0.001). There was also a significant difference between the MCS and LCS groups of 6% (p < 0.001). The HCS group had the highest milk fat concentration (4.47%): it was 4% higher compared with the LCS group (4.28%, p < 0.001) and 5% higher than the MCS group (4.25%, p < 0.001). Milk fat to protein ratio was highest in the HCS group (1.21) and was 7% higher than in the MCS group (1.12, p < 0.001) and 8% higher than in the LCS group (1.11, p < 0.001). The LCS group was determined to have the highest concentration of milk lactose (4.66%). It was 1% higher compared with the MCS group (4.62%, p < 0.001) and 1.07% higher than the HCS group (4.61%, p < 0.001). We can conclude that parity did not affect calf health status and that cows of the HCS group showed symptoms of negative energy balance expressed through higher milk yield, higher milk fat concentration and higher milk fat to protein ratio, with lower milk lactose concentration. Further and more thorough research is needed to evaluate the relationship between pregnant cows and calves.

Trajectories of crop–livestock integration in the context of specialization in Northwest Vietnam

AbstractMixed crop–livestock systems, the world's most widespread farming systems, promote farm resilience through diversification and allow for crop–livestock integration (CLI). Intensification and specialization challenge these systems. In Northwest Vietnam, the standard farm model is based on mixed crop–livestock family farms but is shifting towards more specialized farming systems. The aim of the current study was to identify the new balance between livestock and crops on farms in Northwest Vietnam and to examine the effects of specialization on CLI practices and production system intensification by identifying current CLI practices and performing a retrospective analysis of changes in these practices. One hundred farms were surveyed and 24 interviews on farm trajectories were conducted in Dien Bien district (Dien Bien province) between January and April 2022. Based on the level of CLI and farm diversification, seven types of farms were identified and classified into three categories: (B) mixed farms, (A) farms specializing in livestock and (C) farms specializing in crops. The study of farm trajectories revealed three main changes: the conversion of mixed crop–livestock farms into more specialized crop systems, a change from mixed crop–livestock to more specialized family livestock farms and a change in the management of large ruminant herds and their feed system from free grazing to forage-fed systems. Understanding these changes will help identify drivers and potential constraints to the development of new practices for the integration of crop and livestock farming.

Farm management and economic factors associated with bulk tank total bacterial count in Holstein dairy herds in Iran.

The objectives of this research were (1) to study different factors affecting milk total bacterial count (TBC) and (2) to estimate the economic value associated with TBC in Holstein dairy herds in Iran. The relationships between bulk tank TBC and farm management and economic factors were examined on 56 randomly selected intensive dairy farms. Herd management factors associated with bulk tank TBC were determined using mixed linear models. The median bulk tank TBC for the sample herds was 299 (range 81-1185) × 103 cfu/ml. The average economic premium opportunity from bulk tank TBC was US$ 1.32 per ton of milk ranging from US$ 0.02 per ton of milk for herds applying wet tissue procedures as teat cleaning material and washing the water troughs three times per day to US$ 5.20 per ton of milk for herds with dirty barns. Results showed that the following management factors were associated with low TBC and high economic value: frequency of cleaning water troughs, teat cleaning material, the frequency of milk delivery to the processor, bedding material, herd size, education level of workers, udder washing material, material of milking parlor wall, frequency of disinfection of the calving area, presence of veterinarian, water quality control, having a hospital pen and barn hygiene. In conclusion, our findings highlight the need to pay more attention to farm management issues, particularly farm hygiene practices to reduce milk TBC and so reduce the economic burden of TBC in dairy herds in Iran.

Blood in milk in horned dairy cows–Exploration of incidences and prevention opportunities

Husbandry of horned cows is one alternative to disbudding that respects the animals´ integrity. Concurrently, housing and management should be aligned with the animals' needs to minimize social interactions that can result in integument damage (ID) and udder injuries associated with blood in milk (BM). No information is available on incidences of BM, nor on specific preventive measures. Thus, this study aimed at investigating BM incidences in horned herds and testing whether compliance with guideline recommendations on the prevention of ID also contributes to mitigate BM. Twenty-one farms documented BM, cows’ parity, social rank, and udder damage over seven months covering part of summer with pasture and winter in the barn. A total of 52 factors relating to the guideline were recorded and grouped into ‘milking‘, ‘feeding‘, ‘lying’, ‘walking/activity’ and ‘herd management’. Each factor was categorised into fulfilled or not, and for each group percentages of fulfilment were calculated. Monthly BM incidences varied from 0.3 to 7.8% with 38% being associated with visible udder damage (BMvD). Most cows affected were in the 2nd to 4th lactation (44%) and middle-ranking (58%). A mixed model regarding ‘monthly binomial BMvD’ per farm revealed a higher BMvD risk during the barn season (OR = 2.39), highlighting the importance of pasture to alleviate social conflicts. Higher fulfilment of recommendations concerning 'feeding' and 'walking/activity' was associated with a lower risk (OR = 0.94 and 0.95), indicating that the conflict potential in these areas also plays a role for BMvD and can be lowered by a combination of improvement measures.

Associations between Johne’s disease and fertility in UK dairy herds

The objective of this observational study was to quantify associations between Mycobacterium avium subspecies paratuberculosis (MAP) antibody status and a variety of fertility outcomes, in UK dairy cattle. Longitudinal milk recording, fertility and MAP antibody enzyme-linked immunosorbent assay (ELISA) milk test data were collated retrospectively from 121,762 lactations in 78 herds. Datasets were structured into appropriate units to suit outcomes and enable temporal association between current and future MAP status, and fertility measures. Current MAP status was categorised according to most recent status within 180 days, with time-related future MAP status assigned based on MAP antibody ELISA milk test data for each cow. Multilevel multivariable logistic regression models were used to evaluate associations between MAP status and 21-day pregnancy and submission rate and conception risk. Posterior predictions and cross-validation techniques were used to assess model fit and check model building assumptions. A negative association was found between risk of insemination (Odds Ratio [OR], 0.78; 95% Credible Interval [CI], 0.66–0.92) and conception occurring (OR, 0.65; CI, 0.5–0.84) and transition from negative to non-negative MAP test status in the next 30–90 days. A positive association was observed between risk of insemination (OR, 1.34; CI, 1.16–1.52) and conception occurring (OR, 1.26; CI, 1.11–1.43) and transition from negative to non-negative MAP test status in the next 90–180 days. Current positive MAP test status was negatively and positively associated with insemination (OR, 0.59; CI, 0.49–0.70) and conception risk (OR, 1.12; CI, 0.96–1.30), respectively. Herd managers will have had access to test results, declaring cows with past recent or multiple positive MAP antibody ELISA results not to be bred, negatively influencing insemination risk. Overall, these results demonstrate the temporal association between a positive MAP antibody ELISA result and dairy cow fertility outcomes, with particular variability prior to a positive MAP antibody ELISA result.

The association between insemination eligibility and reproductive performance of nulliparous heifers on subsequent body weight and milk production of primiparous Holstein cows

The objective of this retrospective cohort study was to determine the association between insemination eligibility and reproductive performance of nulliparous heifers with subsequent body weight (BW) at 30 d in milk (DIM) and milk production at wk 4, 8, and 12 of lactation of primiparous cows. The final data set included 1,849 primiparous Holstein cows from a commercial dairy herd. Data extracted from a commercial dairy herd management software program included parent average predicted transmitting abilities (PTA), bovine respiratory disease (BRD) incidence, pregnancies per artificial insemination (P/AI) at first insemination as nulliparous heifers, BW at 30 DIM, percent mature body weight (%MBW), and mean weekly milk production at wk 4, 8, and 12 of lactation. Heifers were eligible for first insemination at 380 d of age and were detected in estrus and artificially inseminated with sexed semen. Quartiles based on BW at 30 DIM and %MBW were created in ascending order as follows: Q1 (lightest; n = 462), Q2 (light-moderate; n = 456), Q3 (moderate; n = 472), and Q4 (heaviest; n = 459). Only Q3 and Q4 cows achieved ≥85% MBW postcalving based on the herd MBW of 686.2 kg. The incidence of BRD during heifer development was greatest for Q1 cows, and Q1 cows had fewer days on feed as heifers than Q4 cows, resulting in a shorter growth period to achieve ≥85% MBW postcalving. Overall, Q1 cows had a greater PTA for daughter pregnancy rate and heifer conception rate than Q4 cows, which was associated with approximately 26 percentage points more P/AI at first insemination as heifers for Q1 than for Q4 cows. Finally, Q1 cows yielded approximately 5 kg per cow/d less milk than Q4 cows. Thus, insemination eligibility and reproductive performance of heifers, calfhood BRD incidence, and genetic potential for reproductive performance were associated with BW at 30 DIM and milk production at wk 4, 8, and 12 of lactation of primiparous cows.

Recent Progress in Studies of Porcine Reproductive and Respiratory Syndrome Virus 1 in China.

Due to the high incidence of PRRSV mutation and recombination, PRRSV infection is difficult to prevent and control in China and worldwide. Two species of PRRSV, Betaarterivirus suid 1 (PRRSV-1) and Betaarterivirus suid 2 (PRRSV-2), exist in China, and PRRSV-1 has always received less attention in China. However, the number of PRRSV-1 strains detected in China has increased recently. To date, PRRSV-1 has spread to more than 23 regions in China. Based on the phylogenetic analysis of ORF5 and the whole genome of PRRSV-1, Chinese PRRSV-1 can be divided into at least seven independent subgroups. Among them, BJEU06-1-like has become the mainstream subgroup in some regions of China. This subgroup of strains has a 5-aa (4 + 1) characteristic discontinuous deletion pattern at aa 357~aa 360 and aa 411 in Nsp2. Previous studies have indicated that the pathogenicity of PRRSV-1 in China is mild, but recent studies found that the pathogenicity of PRRSV-1 was enhanced in China. Therefore, the emergence of PRRSV-1 deserves attention, and the prevention and control of PRRSV-1 infection in China should be strengthened. PRRSV infection is usually prevented and controlled by a combination of virus monitoring, biosafety restrictions, herd management measures and vaccination. However, the use of PRRSV-1 vaccines is currently banned in China. Thus, we should strengthen the monitoring of PRRSV-1 and the biosafety management of pig herds in China. In this review, we summarize the prevalence of PRRSV-1 in China and clarify the genomic characteristics, pathogenicity, vaccine status, and prevention and control management system of PRRSV-1 in China. Consequently, the purpose of this review is to provide a basis for further development of prevention and control measures for PRRSV-1.

Seropositivity of Anti-Toxoplasma gondii and Anti-Neospora caninum Antibodies in Cattle Intended for Human Consumption in an Amazonian Area of North Brazil.

Toxoplasma gondii and Neospora caninum are obligate intracellular intestinal coccidia distributed worldwide, and are causative agents of toxoplasmosis and neosporosis, respectively. The aim of this study was to evaluate the prevalence of anti-T. gondii and anti-N. caninum antibodies and the factors associated with infections in beef cattle intended for human consumption in an Amazonian area of North Brazil. We collected blood samples of 387 cattle from 50 herds located in different municipalities of the State of Rondônia. An epidemiological questionnaire was distributed to farmers, with regard to nutritional, sanitary and reproductive herd management. The samples were identified, refrigerated and sent for serological analyses via IFAT (Immunofluorescent Antibody Test). Among the 387 analyzed animals, 91 (23.5%; CI 95%: 18.8-27.2) were positive for anti-T. gondii antibodies, with titers varying from 1:64 (75.8%) to 1:512 (2.2%). For anti-N. caninum antibodies, only four animals (1%; CI 95%: 0-2.7) were positive, with titers ranging from 1:400 (50%) to 1:1600 (25%). We observed a significant rate of anti-T. gondii antibodies in the variables "pure breed" and "contact with free-range chickens" (p < 0.2). There were no risk factors associated with the presence of anti-T. gondii or anti-N. caninum antibodies. In conclusion, there was a high prevalence of anti-T. gondii antibodies in beef cattle intended for human consumption in the State of Rondônia, Brazil, and a low prevalence of anti-N. caninum antibodies. Longitudinal studies can better elucidate the cause of these prevalence levels and how they could be better prevented and controlled.