Study of the economic impact of cryptosporidiosis in calves after implementing good practices to manage the disease on dairy farms in Belgium, France, and the Netherlands

Cryptosporidium spp. are widespread parasitic protozoans causing enteric infections in humans and animals. The parasites cause neonatal diarrhoea in calves, leading to a high mortality rate in the first three weeks. Losses are significant for farmers, but the cost of cryptosporidiosis remains poorly documented. In the absence of a vaccine, only preventive measures are available to farmers to combat the infection. This study, conducted between 2018 and 2021, aimed to evaluate the economic impact of Cryptosporidium spp. on European dairy farms and monitor changes in costs after implementing disease management measures. First, a field survey was carried out and questionnaires administered to 57 farmers in Belgium, France, and the Netherlands. The aim of the survey was to assess the losses associated with the occurrence of diarrhoea in calves aged between 3 days and 3 weeks. The economic impact of diarrhoea was calculated based on mortality losses, health expenditures, and additional labour costs. To refine the cost estimation specifically for Cryptosporidium spp., stool samples were collected from 10 calves per farm. The prevalence of Cryptosporidium spp. was determined, and the economic impact of diarrhoea was adjusted accordingly. The assumption was made that a certain percentage of costs was attributed to cryptosporidiosis based on the prevalence. These protocols were repeated at the end of the study to observe changes in costs. In the three years, the cost of diarrhoea for the 28 farms that stayed in the panel all along the study improved from €140 in 2018 to €106 on average per diarrhoeic calf in 2021. With a stable prevalence at 40%, the cost of cryptosporidiosis per infected calf decreased from €60.62 to €45.91 in Belgium, from €43.83 to €32.14 in France, and from €58.24 to €39.48 in the Netherlands. This represented an average of €15 saved per infected calf. The methodology employed in this study did not allow us to conclude that the improvement is strictly due to the implementation of preventive measures. However, with 11 million calves raised in the Interreg 2 Seas area covered by the study, it provided valuable insights into the economic burden of Cryptosporidium spp.

Foraging Behavior Shows Individual-Consistency Over Time, and Predicts Range Use in Slow-Growing Free-Range Male Broiler Chickens

Recent research on free-range chickens shows that individual behavioral differences may link to range use. However, most of these studies explored individual behavioral differences only at one time point or during a short time window, assessed differences when animals were out of their social group and home environment (barn and range), and in specific tests or situations. Therefore, it is yet unclear how different behaviors relate to range use and how consistent these behaviors are at the individual level. To fill this gap, we here aimed to describe the behavioral budget of slow-growing male broiler chickens (S757N) when in their social group and home environment during the whole rearing period (from the second week of life to the twelfth week, before slaughter), and to relate observed behavioral differences to range use. For this, we followed a sample of individuals in two flocks (n = 60 focal chickens out of 200 chickens per flock), over two seasons, during three periods: before range access (from 14 to 25 days old), during early range access (first weeks of range access, from 37 to 53 days old), and during late range access (last weeks of range access, from 63 to 87 days old). By the end of each period, individual tests of exploration and social motivation were also performed, measuring exploration/activity and sociability propensities. Our results show that foraging (i.e., pecking and scratching at the ground) was the only behavior that correlated to range use for all three rearing periods, independent of the season. Foraging was also the only behavior that showed within-individual consistency from an early age and across the three rearing periods. Foraging may, therefore, serve as a useful behavioral predictor of range use in free-range broiler chickens. Our study increases the knowledge of how behaviors develop and relate to each other in a domesticated and intensely selected species, and improves our understanding of the biology of free-range broiler chickens. These findings can, ultimately, serve as a foundation to increase range use and improve chicken welfare.

Cross-Border Investigations on the Prevalence and Transmission Dynamics of Cryptosporidium Species in Dairy Cattle Farms in Western Mainland Europe

Cryptosporidium is an apicomplexan parasitic protist, which infects a wide range of hosts, causing cryptosporidiosis disease. In farms, the incidence of this disease is high in animals such as cows, leading to extensive economic loss in the livestock industry. Infected cows may also act as a major reservoir of Cryptosporidium spp., in particular C. parvum, the most common cause of cryptosporidiosis in these animals. This poses a risk to the trading of livestock, to other farms via breeding centres, and to human health. This study is a part of a global project aimed at strategies to tackle cryptosporidiosis. To reach this target, it was essential to determine whether prevalence was dependent on the studied countries or if the issue was borderless. Indeed, C. parvum occurrence was assessed across dairy farms in certain regions of Belgium, France, and the Netherlands. At the same time, the animal-to-animal transmission of the circulating C. parvum subtypes was studied. To accomplish this, we analysed 1084 faecal samples, corresponding to 57 dairy farms from all three countries. To this end, 18S rRNA and gp60 genes fragments were amplified, followed by DNA sequencing, which was subsequently used for detection and subtyping C. parvum. Bioinformatic and phylogenetic methods were integrated to analyse and characterise the obtained DNA sequences. Our results show 25.7%, 24.9% and 20.8% prevalence of Cryptosporidium spp. in Belgium, France, and the Netherlands respectively. Overall, 93% of the farms were Cryptosporidium positive. The gp60 subtyping demonstrated a significant number of the C. parvum positives belonged to the IIa allelic family, which has been also identified in humans. Therefore, this study highlights how prevalent C. parvum is in dairy farms and further suggests cattle as a possible carrier of zoonotic C. parvum subtypes, which could pose a threat to human health.

Working for food is related to range use in free-range broiler chickens

When animals prefer to make efforts to obtain food instead of acquiring it from freely available sources, they exhibit what is called contrafreeloading. Recently, individual differences in behavior, such as exploration, were shown to be linked to how prone an individual may be to contrafreeload. In this work, our main objective was to test whether and how individual differences in range use of free-range broiler chickens (Gallus gallus domesticus) were related to the individual motivation to contrafreeload. We also verified whether other behavioral variations could relate to range use. To that aim, over three different periods (before range access, first weeks of range access, and last weeks of range access), chickens with different ranging levels (low and high rangers) were submitted to a contrafreeloading test and had different behaviors recorded (such as foraging, resting, locomotion) in their home environment. During the contrafreeloading test, chickens were conditioned to one chamber presenting a foraging substrate and mealworms, while in the other chamber, mealworms were freely available on the floor. During testing trials, chickens had access to both empty chambers, and the time spent in each chamber was quantified. On average, low rangers preferred the chamber where mealworms were easily accessible (without the foraging substrate), while high rangers preferred the chamber where mealworms were accessible with difficulty, showing greater contrafreeloading. Out of ten behaviors recorded in chickens' home environment, foraging was the only one that differed significantly between our two ranging groups, with low rangers foraging, on average, significantly less than high rangers. These results corroborate previous experiences suggesting that range use is probably linked to chickens' exploratory trait and suggest that individual differences in free-range broiler chickens are present even before range access. Increasing our knowledge of individual particularities is a necessary step to improve free-range chicken welfare on the farm.

Prevalence and potential influencing factors of non-nutritive oral behaviors of veal calves on commercial farms

Veal calves raised under intensive conditions may express non-nutritive oral behaviors. When expressed in an abnormal way, these behaviors can be a sign of mental suffering and reduced welfare due to a mismatch between environmental or management features and the animal's needs. The aims of this study were to estimate the prevalence of non-nutritive oral behaviors in a large sample of veal farms in Europe and to determine the potential influencing factors present at farm level. Data were collected on 157 commercial veal farms in the 3 main veal-producing countries in Europe (the Netherlands, France, and Italy). Observations of 3 non-nutritive oral behaviors (manipulating substrates, tongue rolling, and manipulating a penmate) were performed when calves were aged 14 wk, and the prevalence of these behaviors was calculated. Information on management practices and characteristics of the building and equipment were collected on all farms to assess potential influencing factors for each of the 3 behaviors. Odds ratios and 95% confidence intervals were calculated to evaluate the effect of each individual factor within a generalized linear model. The mean percentage of calves per farm performing manipulating substrates was 11.0 ± 0.46%, performing tongue rolling 2.8 ± 0 .18%, and manipulating a penmate 2.7 ± 0.09%, with a high range between farms. Allowing more space for calves than the legal minimum requirement of 1.8 m(2)/ calf and housing them in groups of >10 calves/pen reduced the incidences of manipulating substrates and tongue rolling. Incidence of manipulating substrates was lower for calves fed maize silage compared with calves fed cereal grain, pellets, or muesli. A higher risk of tongue rolling was found when baby-boxes (i.e., single housing during the first 5 to 8 wk) were not used. Risk of calves manipulating a penmate was higher for calves of milk- or meat-type breeds compared with dual-purpose breeds and for calves fed with 280 to 380 kg compared with those fed >380 kg of milk powder in total for the fattening period. The study allowed assessment of multiple factors across farms that showed variety in terms of conditions and level of non-nutritive oral behaviors. Identification of the factors influencing non-nutritive oral behavior is helpful to define potential actions that could be taken on farms to improve the welfare of calves and reduce the prevalence of these behaviors.

Prevalence of respiratory disorders in veal calves and potential risk factors

The study aimed to assess the in vivo and postmortem prevalence of respiratory disorders in veal calves and investigate risk factors associated with them. A cross-sectional study was carried out in 174 farms in the 3 major veal meat-producing countries in Europe (50 in France, 100 in the Netherlands, and 24 in Italy). Trained veterinarians visually evaluated individual calves of 1 batch per farm at 3 and 13 wk after arrival and at 2 wk before slaughter to assess the prevalence of hampered respiration, nasal discharge, and coughing. A random sample of lungs belonging to calves of the same batch was monitored at the slaughterhouse for mild to moderate or severe signs of pneumonia, and presence of pleuritis. Data regarding veal calf housing, feeding, and management and specific characteristics of the batch were collected through an interview with the stockperson, and the potential of these as respiratory disease risk factors was assessed. Regardless of the stage of fattening, the prevalence of in vivo signs of respiratory disorders in calves was always <7%. This low prevalence was likely the outcome of the general implementation by veal producers of standardized practices such as prophylaxis, all-in/all-out, and individual daily checks of the calves, which are recognized tools for effective disease prevention and management. However, at postmortem inspection, 13.9% and 7.7% of lungs showed mild to moderate and severe signs of pneumonia, respectively, and 21.4% of the inspected lungs had pleuritis. Thus, even mild clinical signs of respiratory disorder in calves at specific time points during the fattening period may be associated with high prevalence of lungs with lesions at slaughter. Alternatively, clinical symptoms recorded during routine visual inspections of veal calves on-farm may be poor predictors of the true prevalence of respiratory disease in calves. Among all potential risk factors considered, those concerning the characteristics of the batch were predominant but factors related to housing, management and feeding equipment were also relevant. Different risk factors were involved at different stages of the fattening period. Therefore, to overcome respiratory disorders in veal calves, different solutions may apply to different stages of the fattening period.

Cryptosporidium infection in a veal calf cohort in France: molecular characterization of species in a longitudinal study

Feces from 142 animals were collected on 15 farms in the region of Brittany, France. Each sample was directly collected from the rectum of the animal and identified with the ear tag number. Animals were sampled three times, at 5, 15 and 22 weeks of age. After DNA extraction from stool samples, nested PCR was performed to amplify partial 18S-rDNA and 60 kDa glycoprotein genes of Cryptosporidium. The parasite was detected on all farms. One hundred out of 142 calves (70.4%) were found to be parasitized by Cryptosporidium. Amplified fragments were sequenced for Cryptosporidium species identification and revealed the presence of C. parvum (43.8%), C. ryanae (28.5%), and C. bovis (27%). One animal was infected with Cryptosporidium ubiquitum. The prevalence of these species was related to the age of the animal. C. parvum caused 86.7% of Cryptosporidium infections in 5-week-old calves but only 1.7% in 15-week-old animals. The analysis of the results showed that animals could be infected successively by C. parvum, C. ryanae, and C. bovis for the study period. C. parvum gp60 genotyping identifies 6 IIa subtypes of which 74.5% were represented by IIaA15G2R1. This work confirms previous studies in other countries showing that zoonotic C. parvum is the dominant species seen in young calves.