The impact of disease and disease prevention on sheep welfare

Herd health and reproductive management associated with lamb weight gain and mortality in sub-Saharan drylands-a case from Ethiopia

Sheep are important for food and livelihood security in sub-Saharan Africa, and maximizing lamb weight gain while minimizing mortality is essential to improve production. Using the Menz sheep breeding villages of Amhara region in Ethiopia as a case study, the weight gain and mortality rate of 208 lambs were monitored during their first 5 months of life. The study was conducted in intervention and control villages, where the intervention villages were part of community-based breeding programmes and had participated in various projects aiming to improve sheep production and management. Multivariable linear regression analysis was conducted to detect associations between weight gain from birth to 1 month, and birth to 5 months, and different lamb and ewe characteristics, farmer education, application of management routines, and presence of village level sheep management interventions. In general, lambs from intervention villages, without certain signs of diseases, whose mothers were 2 years or older, had a body condition score of more than 2 on a 5-point scale, and who originated from flocks where disease prevention strategies had been implemented, had gained more weight. Overall lamb mortality was 6.8% with most deaths occurring before 1 month of age. This study highlights that health interventions in ewes improve lamb survival and weight gain and that the care of lambs during the first month of life is crucial for overall herd productivity.

Preventive herd management practices and their effect on lamb mortality in Ethiopia

According to previous studies, lamb mortality is high in the Ethiopian highlands. The present study aims to evaluate the execution of preventive sheep herd health management practices with respect to if, and how, such practices are linked to occurrence of lamb mortality. Interviews were performed with 74 sheep-owning households participating in a capacity development program on livestock and 69 households not participating in such program. To evaluate the impact of combinations of performed practices, a scoring system was developed-the households retrieved a higher score the more desired routines were accomplished. To identify which practices had the highest impact on lamb mortality, a similar score was calculated for each phase of the sheep reproductive year, creating sub-scores for each phase. The results showed a significant (p < 0.05) negative correlation between the total number of performed practices and occurrence of lamb mortality, indicating a lower occurrence of lamb mortality the more desired practices implemented. Further analysis of sub-scores showed significant (p < 0.05) negative correlations between a higher number of performed desired practices during gestation period and during lambing. Conclusively, the study indicates that preventive herd management routines are beneficial for lamb survival, foremost when enforced during the gestation period and around lambing-hence, this is where to focus future interventions.

Experimental Study of the Potential Role of Salmonella enterica subsp. diarizonae in the Diarrhoeic Syndrome of Lambs

The objectives of this experimental work were the evaluation of the potential role of Salmonella enterica subsp. diarizonae in diarrhoeic syndrome in lambs and the investigation of facets of the pathogenesis of the infection. In total, 12 lambs were challenged orally on the first day of life, with a S. enterica subsp. diarizonae isolate from a clinical case of diarrhoeic syndrome. Sequential blood, faecal and buccal samples were collected from lambs and faecal and milk samples were taken from their dams. Lambs were euthanised 1, 2, 4, 7, 10, 14 and 21 days after challenge. Samples were processed for recovery of the challenge organism; they were also subjected to examination by PCR for detection of the invA gene. Tissue samples from lambs were also examined as above and histopathologically. S. enterica subsp. diarizonae was recovered from faecal samples of all lambs, in total, from 45/77 samples (median duration: 2.4 days post-inoculation). It was also recovered from buccal samples (10/77) from seven lambs (median duration: 0.8 days), and from tissue samples (small intestine, abomasum, liver, gallbladder) of nine lambs. It was recovered from two consecutive milk samples from the same ewe, but not from any faecal sample from ewes. The invA gene was detected in samples from all lambs (median duration: 5.5 days in faecal and 1.3 days in buccal samples), as well as in milk samples from three ewes. Histopathological findings included abomasitis with subepithelial presence of eosinophils, lymphocytes and plasma cells, consistently observed in all lambs. In the small intestine, salient lesions initially included distension and oedema of intestinal villi, leucocytic infiltration and hyperplasia of lymphoid nodules with apparent germinal centres; this was followed at later stages by atrophy and/or degeneration of the lymphoid tissue of the intestine with marked subepithelial infiltration of lymphocytes, plasma cells and eosinophils.

Test positivity for Maedi-Visna virus and Mycobacterium avium ssp. paratuberculosis in Sarda ewes: Effects on milk composition and coagulation traits and heritability estimates for susceptibility

Maedi-Visna virus (MVV) and Mycobacterium avium ssp. paratuberculosis (MAP) are two pathogens that cause chronic, production-limiting diseases in dairy sheep. Although they are present worldwide, there are no detailed reports on their actual effects on milk traits in the literature. This study was designed to investigate the effects of test positivity to MVV and MAP on ovine milk yield, composition and coagulation properties, and curd-firming over time (CF_t) variables in clinically healthy animals at the field level. The additive genetic variation and heritabilities of MVV and MAP positivity were also estimated. Milk samples were collected from 1,079 Sarda sheep kept on 23 farms, and pedigree information was obtained from the flock book. Milk yield was also recorded on the sampling date. Positivity for MVV and MAP was determined from milk samples using indirect ELISA test kits. Milk composition traits were measured by spectroscopy, milk coagulation properties were measured with a Formagraph (Foss Italia, Padua, Italy), and CF_t traits were calculated using the data from the Formagraph diagram. The effects of MVV and MAP positivity on milk traits were determined through a set of mixed linear models, which took into account various sources of variation, such as days in milk, parity, and flock effects, and included the effects (positive or negative) of the 2 pathogens. A Bayesian threshold sire model with sire relationship was used to estimate genetic variation and heritability. The overall animal prevalence of MVV-positive ewes was 43.6%; on only 1 farm of the 23 tested were all sampled ewes negative. An overall animal prevalence of 10.6% was recorded for MAP, with 4 farms at 0%. Positivity for MVV significantly affected the logarithmic score of the bacterial count, curd firmness after 30 min and 45 min, and the curd-firming instant rate constant. We found significant effects of MAP infection on milk composition, pH, and rennet coagulation time. The mean of the posterior distributions of heritability estimates on the liability scale was 0.15 for MAP and 0.07 for MVV. Our results demonstrate that only a few traits are negatively affected by MVV and MAP positivity, and that there is exploitable genetic variation in MVV and MAP susceptibility in dairy sheep.

Differential quantitative proteomics study of experimental Mannheimia haemolytica mastitis in sheep

Objective was the differential quantitative proteomics study of ovine mastitis induced by Mannheimia haemolytica; clinical, microbiological, cytological and histopathological methods were employed for confirmation and monitoring. Proteins were separated by two-dimensional gel electrophoresis (2-DE) for all samples and differentially abundant proteins were identified by mass spectrometry; comparisons were performed with pre- (blood, milk) and post- (milk of contralateral gland) inoculation findings. Animals developed mastitis, confirmed by isolation of challenge strain and increase of neutrophils in milk and by histopathological evidence. In blood plasma, 33 differentially abundant proteins (compared to findings before challenge) were identified: 6 with decrease, 13 with new appearance and 14 with varying abundance. In a post-challenge milk whey protein reference map, 65 proteins were identified; actin cytoplasmic-1, beta-lactoglobulin-1/B, cathelicidin-1 predominated. Further, 89 differentially abundant proteins (compared to findings before challenge) were identified: 18 with decrease, 53 with new appearance, 3 with increase and 15 with varying abundance; 15 proteins showed status changes in blood plasma and milk whey. Differential abundance from inoculated and contralateral glands revealed 74 proteins only from the inoculated gland. Most differentially abundant proteins in milk whey were involved in cell organisation and biogenesis (n = 17) or in inflammatory and defence response (n = 13). SIGNIFICANCE: The proteomes of blood and milk from ewes with experimental mastitis caused by Mannheimia haemolytica and the differential proteomics in sequential samples after challenge are presented for the first time. This is the first detailed proteomics study in M. haemolytica-associated mastitis in ewes. An experimental model fully simulating natural mastitis has been used. Use of experimentally induced mastitis minimised potential variations and allowed consistency of results. The study included evaluation of changes in blood plasma and milk whey. Protein patterns have been studied, indicating with great accuracy changes that had occurred as part of the disease process and development, during the acute phase of infection. Relevant protein-protein interactions were studied. The entirety of proteomics findings has suggested that affected ewes had mounted a defence response that had been regulated by many proteins (e.g., cathelicidins, haptoglobin, serum amyloid A) and through various pathways (e.g., acute phase response, binding and transporting significant ions and molecules); these were interdependent at various points. Potential biomarkers have been indicated for use in diagnostic assays of mastitis.

Evidence of respiratory syncytial virus and parainfluenza-3 virus in Mexican sheep

This is a first report in Mexico of the presence of antibodies against respiratory syncytial virus (RSV) and parainfluenza-3 virus in Mexican sheep in different productive stages. We determine the association of serological positivity with age and production system, and obtain molecular evidence of infection by both virus. RSV prevalence in adult sheep was 47% (49/105) at the tropic and 64% (63/99) at the uplands. A significant difference in RSV seropositivity between animals from the tropic and the uplands was observed (P < 0.05). Seropositivity correlated with production system (P = 0.003, OR = 2.042), with a risk of showing antibodies was 2.042 times higher in sheep under an extensive production system. A significant difference in PI3V seropositivity between animals from either provenance (P = 0.017, OR = 0.475) were also found, with a risk of showing antibodies 0.475 times higher in sheep under an extensive production system. Genetic material from RSV and PI3V was identified by RT-PCR in nasal swab samples from clinically healthy lambs and confirmed by sequencing and phylogenetic analysis. Serological results show that sheep are susceptible to infection by both viruses, and molecular results suggest that the identified antibodies are result of natural infections and reinfections.

Experiences from the 2014 outbreak of bluetongue in Greece

Objective of this paper was to review relevant work and to present a general account of the bluetongue outbreak, which occurred in Greece in 2014. In total, 2895 outbreaks of the disease have been reported by the veterinary authorities of Greece; sheep, goats and cattle were affected with officially reported morbidity rates of 11.0%, 2.0% and 3.5%, respectively. No vaccinations were allowed and conservative measures were implemented to attempt to limit the disease, which at the end had expanded throughout the country. In field investigations, a significantly higher bluetongue morbidity rate (27.5%) in sheep has been reported. During that work, clinical anaemia was encountered, which was characterised as macrocytic, hypochromic, regenerative and non-haemolytic. Other investigations, which are reviewed in this paper, have described an outbreak of Citrobacter freundii-associated enteritis in newborn kids, offspring of goats subclinically infected with Bluetongue virus, increased rate of early embryonic deaths, reduced conception rates, increased incidence risk of mastitis and reduced milk yield in herds of subclinically-infected cattle and detection of the virus from hunter-harvested tissue samples of roe-deer. In 2015, vaccines against the disease have been licenced; vaccinations started in May 2015. Then, in 2015, only one outbreak of the disease was confirmed, which could have been the result of a combination of reasons acting concurrently to prevent further cases.

The Challenges to Improve Farm Animal Welfare in the United Kingdom by Reducing Disease Incidence with Greater Veterinary Involvement on Farm

Simple Summary

Sick cattle and sheep are often treated by farmers without prior veterinary examination and, as a consequence, incorrect diagnoses and inappropriate therapies are common, but these failings largely go undetected and unreported. Many farmers maintain that market forces render veterinary care of individual sick sheep and cattle too expensive. Delays in requesting veterinary attention are not uncommon causing unnecessary animal suffering and a poorer outcome. Incidence rates of endemic diseases in the United Kingdom are too high, causing animal welfare concerns, but these could be reduced by the implementation of proven veterinary flock/herd health programmes.

Abstract

The Cattle Health and Welfare Group of Great Britain report (CHAWG; 2012) lists the most important cattle diseases and disorders but fails to fully acknowledge the importance of animal mental health and; in so doing; misses the opportunity to further promote animal welfare. There are effective prevention regimens; including vaccination; husbandry and management strategies for all ten listed animal health concerns in the CHAWG report; however control measures are infrequently implemented because of perceived costs and unwillingness of many farmers to commit adequate time and resources to basic farm management tasks such as biosecurity; and biocontainment. Reducing disease prevalence rates by active veterinary herd and flock health planning; and veterinary care of many individual animal problems presently “treated” by farmers; would greatly improve animal welfare. Published studies have highlighted that treatments for lame sheep are not implemented early enough with many farmers delaying treatment for weeks; and sometimes even months; which adversely affects prognosis. Disease and welfare concerns as a consequence of sheep ectoparasites could be greatly reduced if farmers applied proven control strategies detailed in either veterinary flock health plans or advice available from expert veterinary websites. Recent studies have concluded that there is also an urgent need for veterinarians to better manage pain in livestock. Where proven treatments are available; such as blockage of pain arising from ovine obstetrical problems by combined low extradural injection of lignocaine and xylazine; these are seldom requested by farmers because the technique is a veterinary procedure and incurs a professional fee which highlights many farmers’ focus on economics rather than individual animal welfare.

Health of farmed fish: its relation to fish welfare and its utility as welfare indicator

This brief review focuses on health and biological function as cornerstones of fish welfare. From the function-based point of view, good welfare is reflected in the ability of the animal to cope with infectious and non-infectious stressors, thereby maintaining homeostasis and good health, whereas stressful husbandry conditions and protracted suffering will lead to the loss of the coping ability and, thus, to impaired health. In the first part of the review, the physiological processes through which stressful husbandry conditions modulate health of farmed fish are examined. If fish are subjected to unfavourable husbandry conditions, the resulting disruption of internal homeostasis necessitates energy-demanding physiological adjustments (allostasis/acclimation). The ensuing energy drain leads to trade-offs with other energy-demanding processes such as the functioning of the primary epithelial barriers (gut, skin, gills) and the immune system. Understanding of the relation between husbandry conditions, allostatic responses and fish health provides the basis for the second theme developed in this review, the potential use of biological function and health parameters as operational welfare indicators (OWIs). Advantages of function- and health-related parameters are that they are relatively straightforward to recognize and to measure and are routinely monitored in most aquaculture units, thereby providing feasible tools to assess fish welfare under practical farming conditions. As the efforts to improve fish welfare and environmental sustainability lead to increasingly diverse solutions, in particular integrated production, it is imperative that we have objective OWIs to compare with other production forms, such as high-density aquaculture. However, to receive the necessary acceptance for legislation, more robust scientific backing of the health- and function-related OWIs is urgently needed.