Movement standstills are a key strategy for reducing farm contacts during a foreign animal disease outbreak; however, essential activities such as feed delivery may continue under managed conditions. We simulated African swine fever (ASF) transmission across a dense swine production region of the southeastern U.S., incorporating local spread, animal movements, and truck-mediated pathways. We compared four scenarios: baseline, with animal movements and truck contacts active; trucks-off, with truck contacts removed but animal movements active; feed-only, with animal movements halted, but feed delivery continued; and standstill, with animal and truck pathways removed. ASF introductions were stratified by farm density and vehicle network node strength, resulting in nine density–vehicle network node strength categories. Outbreak size varied by initial farm context, with cumulative infected farms ranging from 17.6 to 52.5 in the low-density, low-vehicle network node strength category and from 348.2 to 376.0 in the high-density, high-vehicle network node strength category. Relative to complete standstill, the baseline and trucks-off scenario produced medians of 34.8 (IQR: 29.2–47.3) and 25.4 (IQR: 20.8–41.1) additional infected farms, respectively. In contrast, the feed-only scenario produced a median of 11.3 (IQR: 5.8–15.0) additional infected farms; a 6.4% increase over standstill compared with 24.1% under baseline and 18.6% under trucks-off. We demonstrated that feed delivery may sustain transmission during movement restrictions, but its effect depends on the farm density and vehicle network node strength of the initially infected farm.
Groundwater is a plausible medium for transmission of pathogens on and between swine farms that is not addressed in current biosecurity practices. Waterborne disease transmission is uninvestigated for swine. Typical assessments of farm water quality include basic microbial measures, which may not reveal pathogens of concern. This study aimed to assess endemic swine pathogens and manure markers in private wells supplying 40 Iowa swine farms. Wells were sampled in spring (n = 20) or fall (n = 20) using dead-end ultrafiltration, which improves sensitivity of groundwater-borne pathogen detection and allows sampling of viruses, bacteria, and protozoa. Samples were analyzed by quantitative polymerase chain reaction for porcine reproductive and respiratory syndrome virus, porcine epidemic diarrhea virus, porcine circovirus 2, rotavirus group C, enteropathogenic Escherichia coli, Salmonella spp., swine Bacteroides (Pig-1-Bac and Pig-2-Bac), and Cryptosporidium spp. Ten of 40 wells tested positive for at least one microbe. Detection of swine Bacteroides markers in seven wells indicated that a pathway existed from manure to groundwater. Pathogen detections included porcine circovirus type 2 on three farms and Cryptosporidium spp. at two farms. Five samples contained two or more target organisms. Field controls were collected with all samples, and laboratory controls were included for all manipulations and analyses. This study suggests the possibility of waterborne pathogen transmission to swine populations and motivates development of water biosecurity measures on swine farms.
Concerns regarding the welfare of sows during the farrowing and lactation periods, which have been associated with the use of conventional crates, have prompted the development of farrowing pen designs. The present study sought to compare the effects of two commercial farrowing systems with temporary crating, treatment 1 (T1, Low-Walled Farrowing Pen, LWFP) versus treatment 2 (T2, High-Walled Farrowing Pen, HWFP), on the welfare indicators, lesion dynamics and salivary cortisol concentrations of lactating sows. The two farrowing systems with temporary crating, sampling time (day 3 vs. day 29 of lactation) and their interaction were the primary factors under investigation. A total of 180 multiparous sows were assessed across four independent replicates. Ordinal and dichotomous indicators were analysed using mixed-effects models, while salivary cortisol concentrations were analysed using linear mixed models. A reduction in skin damage severity during lactation was observed in both systems (p < 0.001). However, a farrowing system × time interaction was detected (p < 0.05), with a higher proportion of lesion-free sows at day 29 in the HWFP system. Mammary gland lesion severity was significantly lower in this system (p < 0.01), whereas shoulder ulcers increased over time irrespective of housing system (p < 0.001). In the HWFP system, sows exhibited higher salivary cortisol concentrations (p < 0.05), and increased cortisol levels were associated with the presence of shoulder ulcers and carpal lesions (p < 0.05). The findings indicate that, while farrowing systems with temporary crating may reduce certain lesion-related risks, their welfare outcomes depend on specific design characteristics, handling and management conditions. Consequently, a thorough evaluation encompassing lesion trajectories and physiological stress indicators is imperative to facilitate evidence-based decision-making during commercial housing transitions.
