Sheep Udder Research Articles

Utilization of 2D and 3D cell cultures for the modelling of intramammary infection in sheep

Ovine mastitis is defined as the inflammation of the sheep udder, most commonly caused in response to intramammary infections. Based on the occurrence of clinical signs, mastitis is characterized as either clinical or subclinical (SCM). The impact of ovine SCM on the overall sustainability of dairy sheep farms has been substantially documented underpinning the significance of efficient diagnosis. Although SCM can be detected in cows, the performance and the validity of the methods used do not transfer in dairy sheep. This fact challenges the development of evidence-based ovine udder health management protocols and renders the detection and control of ovine mastitis rather problematic. Currently, cell culture-based models are being successfully used in biomedical studies and have also been effectively used in the case of bovine mastitis. The objective of the present study was to culture ovine primary mammary cells for the development of 2D and 3D cell culture-based models for the study of ovine mammary gland and to focus on the first stages of the intramammary infection by common mastitis-inducing pathogens. Cells were infected by E. coli and S. aureus mimicking the first stages of natural intramammary infections. The secreted proteins were subjected to mass-spectrometry resulting in the identification of a total of 79 distinct proteins. Among those, several had already been identified in healthy or mastitic milk, while others had not been previously detected for in the ovine mammary secretome. Our results suggest that the development of cell-based models for studying specific stages of intramammary infection has the potential to be beneficial for the udder health management in dairy sheep.

Milk yield of West African Dwarf sheep as affected by udder stimulation, stage of lactation and parity

This study was conducted to investigate the milk yield of West African Dwarf sheep as affected by udder stimulation, stage of lactation and parity. The study involves 12 matured lactating ewes weighing between 16 and 24 kg live weights in a semi intensive system of management. For udder stimulation, the animals were divided into 2 groups; 6 animals were stimulated by massaging, cleaning and drying the udder for 2 minutes before milking while the other 6 were not stimulated, the udder were just milked. Stage of lactation was divided into 4; early, mid, late, and very late respectively with 3weeks interval for all the animals. 4 animals were on first parity while 8 animals were on second parity. The animals were allowed to graze on an established paddock consisting of Stylosanthes hamata, Panicum maximum, Pennisetum purpureum etc. for 5 hours and then supplemented with concentrate (17% CP at 5% body weight). Each quarter of the udder was hand milked unilaterally twice per week at 8.00am for 12 weeks. The result of the study showed that daily milk yield in each of the quarter of the udder (left and right) was not significantly (P>0.05) different. Udder stimulation and stage of lactation had significant (P<0.05) effect on daily milk yield while parity and mammary gland position (left and right ) did not significantly affect daily milk yield. The interaction between udder stimulation and stage of lactation as well as interaction between udder stimulation and parity had significant (P><0.05) effect on daily milk yield in WAD sheep. Therefore it is recommended that sheep udder be stimulated at late and very late stages of lactation to enhance milk production. ><0.05) effect on daily milk yield while parity and mammary gland position (left and right ) did not significantly affect daily milk yield. The interaction between udder stimulation and stage of lactation as well as interaction between udder stimulation and parity had significant (P<0.05) effect on daily milk yield in WAD sheep. Therefore it is recommended that sheep udder be stimulated at late and very late stages of lactation to enhance milk production.

Short communication: Diversity of staphylococci isolated from sheep mastitis in northern Algeria

Mastitis in ruminants is an important disease with major effects on both the economy and animal welfare. It is caused by major pathogens such as Staphylococcus aureus and minor pathogens such as coagulase-negative staphylococci. The objective of this study was to identify and characterize staphylococci as a cause of sheep mastitis in Algeria. In this study, 123 milk samples were collected directly from the udder of sheep suffering from clinical mastitis in 2 provinces in Algeria. Recovered isolates were identified using MALDI-TOF mass spectrometry. Virulence-associated and antimicrobial resistance genes as well as clonal complexes (CC) of S. aureus were determined using microarray-based analysis. A total of 45 staphylococci isolates were cultivated from sheep milk samples, and 28 S. aureus were identified as methicillin susceptible (62.2%). Seventeen other Staphylococcus isolates of different species were identified using MALDI-TOF mass spectrometry. Subsequent microarray analysis typed the methicillin-susceptible S. aureus to 6 CC: CC8-MSSA, CC97-MSSA, CC130/521-MSSA, CC479-MSSA, CC522-MSSA, and CC705-MSSA. The accessory gene regulator agrIII and the ruminant leukocidin genes lukF-P83 and lukM were found in all isolates of CC130/521, CC479, CC522, and CC705. The toxic shock syndrome toxin gene tst1 was detected exclusively in CC130/521. Additionally, virulence-associated genes (sea, sed, sak, hld, hlgA, edinB, andothers) were detected. The presence of antibiotic resistance genes [blaZ,erm(B), and tet(K)] was detected in small numbers of staphylococci. Staphylococci possessing these genes are considered potential hazards for farm animals, farmers, and consumers. Data concerning the prevalence and diversity of staphylococci causing mastitis in sheep from Algeria are lacking. Presented results on different aspects about staphylococci in Algerian sheep populations should at least partially close that gap. However, further extensive studies covering more geographical regions are needed to assess the epidemiological risk.

Mammary Defences and Immunity against Mastitis in Sheep.

Simple SummaryThe article reviews the defence mechanisms and the relevant processes that occur in the udder of sheep. Due to the importance of the udder in milk production, animals display many defences to protect the organ. These include the teats, the epithelial and the white-blood cells in the udder, the immunoglobulins and chemical substances that all participate in the various processes. These are influenced by many factors, animal- or management-regulated, which must be taken into account in the formulation of prevention schemes against mastitis in sheep.The objectives of this review paper are to present udder defences, including teat of the udder, mammary epithelial cells, leucocytes, immunoglobulins, complement system and chemical antibacterial agents, to describe cooperation and interactions between them and to elaborate on potentials regarding their significance in mammary immunisation strategies. The teat of the udder provides initial protection to the mammary gland. The mammary epithelial cells synthesise antibacterial proteins and the leucocytes produce various inflammation mediators (cytokines or chemokines), phagocytose bacteria and recognise antigenic structures. In the mammary gland, four immunoglobulins (IgG1, IgG2, IgM and IgA) have important roles against bacterial pathogens. The complement system is a collection of proteins, participating in the inflammatory process through various pathways. Other components contributing to humoral mammary defence include lactoferrin, lysozyme and the lactoperoxidase/myeloperoxidase systems, as well as oligosaccharides, gangliosides, reactive oxygen species, acute phase proteins (e.g., haptoglobin and serum amyloid A), ribonucleases and a wide range of antimicrobial peptides. Management practices, genetic variations and nutrition can influence mammary defences and should be taken into account in the formulation of prevention strategies against ovine mastitis.

Draft Genome Sequence of Corynebacterium pseudotuberculosis Strain PA07 Biovar ovis, Isolated from a Sheep Udder in Amazonia.

ABSTRACTIn this work, we present the draft genome sequence of Corynebacterium pseudotuberculosis strain PA07 biovar ovis, isolated from a caseous secretion from a sheep udder in Pará, Brazil. The genome contains 2,320,235 bp, 52.2% G+C content, 2,191 coding sequences (CDSs), five pseudogenes, 48 tRNAs, and three rRNAs.

Draft Genome Sequence of Bacillus licheniformis S127, Isolated from a Sheep Udder Clinical Infection.

Bacillus licheniformis is a Gram-positive biofilm- and endospore-forming bacterium, which contaminates dairy products and can be pathogenic to humans. The draft genome sequencing for B. licheniformis strain S127 is reported here, providing genetic data relevant to the ability of this strain to sustain its survival in the dairy industry.

Theoretical analysis of the microwave radiation interaction with animals suffering by mastitis

To analyze the distribution of electric intensity of radio-pulse radiation in the mammary gland of ewes it is developed the model in the form of a truncated circular cone shape, filled with an isotropic medium with a different dielectric permittivity. In this article we solve the problem of homogeneous Maxwell equations describing distribution of the electric and magnetic fields in the module of the breast ewes by the method of integral equations. As a result of reforms, the initial transient problem has been reduced to the following series of problems of the diffraction of,monochromatic fields with frequency ωm =±12±…. for the area of the mammary gland of ewes. Formulated diffraction problems are reduced to integral equations for the field of the mammary gland of ewes. To this aim, using Green’s formula, it was obtained integral equation for the distribution of the electric field inside mammary gland. A theoretical analysis found that for the treatment of infectious mastitis of ewes should be carried out using radio-pulse radiation with frequency 30,8 GHz, pulse width 1•10-6 sec, pulse repetition period 1•10-4 sec, radio pulse amplitude within the sheep udder (pulse, argon irradiation time of patients) for the treatment of mastitis of the ewes.

Udder disease etiology, milk somatic cell counts and NAGase activity in Israeli Assaf sheep throughout lactation

Bacterial pathogens causing udder infections in Israeli Assaf dairy sheep were identified and changes occurring throughout lactation were monitored to study the correlation between the contaminant and the severity of the infection, as measured by somatic cell count (SCC) and NAGase tests. A total of 159 Israeli Assaf dairy sheep on one farm, in their first (69), second (13) or third and more (77) lactations were included in this study. Udder halves were tested for bacterial condition, SCC and NAGase activity 2–3 weeks post lambing and every 4 weeks after until drying-off. At first sampling, in 60.7% (193/318 quarters) of the halves no bacterial growth (NBG) was detected. Different species of coagulase negative staphylococci (CNS) were the main pathogen group in infected udders. Streptococci were isolated from 14 halves, most of them in the two udder halves. The percent of udder infection in sheep in their third or further lactations was 2.8 greater ( P<0.05) than in that of sheep in their first lactation. During the lactation, 90.6% of the halves did not change their classification status, suggesting that most infections occur before lambing and/or during the following first few days. The arithmetic mean of SCC and NAGase of total half udder milk and samplings (during the lactation) were 1144±48×10 3 cells/ml and 49.4±2.5, respectively. The average SCC in the milk of halves classified as NBG was 321±35×10 3 cells/ml and was not significantly changed during the lactation period. In halves infected with CNS, average SCC was 1371±150×10 3 cells/ml at the first testing and increased to 2129±347×10 3 cells/ml at drying-off. No significant differences were found in SCC and NAGase activity between the different species of the CNS. The mean SCC over the types of bacteria isolated, lactation number and days in lactation was significantly different ( P<0.0001). In 4% of the halves, from all samples, SCC was above 5000×10 3 cells/ml although no bacteria were detected in their milk. The higher SCC in the CNS infected halves contrasted with the more moderate SCC found in dairy cows similarly infected, suggesting that the sheep udder has a lower resistance and an augmented immunological response against this group of bacteria. Thus, this should be considered accordingly in schemes for sheep’s milk quality payment.

Effect of intramammary infusion of β-1,3-glucan or interleukin-2 on leukocyte subpopulations in mammary glands of sheep

Abstract Objective To investigate effects of intramammary infusion of β-1,3-glucan or recombinant ovine interleukin-2 (rOvIL-2) on blood and mammary leukocyte subpopulations and their expression of various surface antigens in sheep. Animals 12 healthy multiparous, nonpregnant, non-lactating fine-wool Merino ewes. Procedure β-1,3-Glucan in pyrogen-free saline solution (PFSS; n = 6), rOvIL-2 in PFSS (3), or PFSS (3) was infused on days 0 and 7 in 1 udder half of each ewe. Jugular vein blood and mammary secretion samples were taken before infusion and on days 2, 7, and 21 after infusion. Total and differential leukocyte counts were obtained, and blood and mammary cells were labeled for flow cytometry. Results Slight swelling of the mammary glands was observed on day 2 after rOvIL-2 but not after β-1,3-glucan infusion. Both substances induced significant increase in mammary secretion leukocyte numbers, compared with controls. β-1,3-Glucan induced an influx of monocyte/macrophages, whereas neutrophils were the predominating cell population after rOvIL-2 infusion. β-1,3-Glucan induced selection for CD4+, B-cell+, WC1+, and L-selectin+ lymphocytes on day 14 after infusion. By comparison, rOvIL-2 induced selection for B-cell+ and L-selectin+ lymphocytes on days 14 and 21 and depletion of CD8+ and, to some degree, of IL-2R+ lymphocytes. β-1,3-Glucan induced an increase in the proportion of CD14+ leukocytes, indicating selective migration of monocyte/macrophages to the nonlactating udder. Conclusion β-1,3-Glucan and rOvIL-2 can modulate nonspecific immunity in the udder of sheep but may exert their effects by differing mechanisms. Clinical Relevance Stimulation of the nonspecific defense against udder infections may improve control of mastitis. (Am J Vet Res 1999;60:703–707)

Non-clinical intramammary infection in lactating ewes and its association with clinical mastitis

A bacteriological survey for the study of non-clinical intramammary infection in the sheep udder was carried out in 88 Assaf ewes. A mean infection prevalence in the first few weeks of lactation was 55%. The most common bacterial isolates were Micrococcus spp. followed by coagulase negative staphylococcus, together accounting for 93% of the total number of isolates. An infection prevalence of 54% was found in ewelambs 2 days after their first lambing, indicating a marked new infection rate around lambing. Generally, the course of lactation was characterized by dynamic changes of new infection and spontaneous resolution. About 5% of half udders examined developed clinical mastitis. The comparison of bacteriological data from mastitic milk samples and from samples taken from the same half udders before the appearance of the clinical disease could not support the theory that in sheep, mastitis is a clinical exacerbation of a non-clinical intramammary infection.

Thermal effects of reproductive hormones on the sheep udder.

The thermal effect of reproductive hormones on the sheep udder was tested in five ewes at the end of their breeding season. Radiotelemetry was used to provide continuous recordings of deep body temperature (Tb), udder skin temperature (Tud), and back skin temperature (Tbk) while the animals were held in a controlled-environment isolation chamber. Injections of estradiol (1.0 and 2.5 mg, im) resulted in an increase in Tud, but not in Tb, and only occasionally in Tbk. The amplitude of the rise in Tud varied from 0.4 to 3.8 degrees C and the rise persisted over 48 h following injection. Injections of saline, prostaglandin (PGF2alpha), or progesterone did not affect Tud, and injections of pyrogen (typhoid vaccine) elicited only an insignificant change in Tud concurrent with substantial increases in Tb and Tbk.

Incorporation of DL-[2-14C]ornithine and DL-[5-14C]arginine in milk constituents by the isolated lactating sheep udder.

1. Lactating mammary glands of sheep were perfused for several hours in the presence of dl-[2-(14)C]ornithine or dl-[5-(14)C]arginine and received adequate quantities of acetate, glucose and amino acids. 2. In the [(14)C]ornithine experiment 1.4% of the casein and 1% of the expired carbon dioxide came from added ornithine; 96% of the total radioactivity in casein was recovered in proline; 13% of the proline of casein originated from plasma ornithine. 3. In this experiment the results of chemical degradation of proline of casein as well as relative specific activities in the isolated products are consistent with the view that ornithine is metabolized, by way of glutamic gamma-semialdehyde, to proline or glutamic acid. 4. In the [(14)C]arginine experiments 3% of the casein and 1% of the expired carbon dioxide came from arginine; 84% of the arginine and 9% of the proline of casein originated from plasma arginine. 5. In these experiments the relative specific activities of arginine, ornithine and proline in plasma are in agreement with the view that arginine is metabolized by way of ornithine to proline. The conversion of arginine into ornithine is probably catalysed by arginase, so that arginase in mammary tissue may be involved in the process of milk synthesis.