Milk N-acetyl-beta-D-glucosaminidase and serum albumin as indicators of subclinical mastitis in the camel

Camel Milk: Antimicrobial Agents, Fermented Products, and Shelf Life

The camel milk (CM) industry has witnessed a notable expansion in recent years. This expansion is primarily driven by the rising demand for CM and its fermented products. The perceived health and nutritional benefits of these products are mainly responsible for their increasing popularity. The composition of CM can vary significantly due to various factors, including the breed of the camel, its age, the stage of lactation, region, and season. CM contains several beneficial substances, including antimicrobial agents, such as lactoferrin, lysozyme, immunoglobulin G, lactoperoxidase, and N-acetyl-D-glucosaminidase, which protect it from contamination by spoilage and pathogenic bacteria, and contribute to its longer shelf life compared to bovine milk (BM). Nevertheless, certain harmful bacteria, such as Listeria monocytogenes, Yersinia enterocolitica, and Escherichia coli, have been detected in CM, which is a significant public health concern. Therefore, it is crucial to understand and monitor the microbial profile of CM and follow good manufacturing practices to guarantee its safety and quality. This review article explores various aspects of CM, including the types of beneficial and harmful bacteria present in it, the composition of the milk, its antimicrobial properties, its shelf life, and the production of fermented CM products.

Pathological insights into camel mastitis

Camel is a multipurpose animal bred to produce milk, meat, and transport and serves as a financial reserve for pastoralists by playing an important role in social prestige and prosperity. Camel milk is a good substitute for human milk because of its exceptional nutritional properties. Udder infections are considered one of the main limitations to camel farming. In recent decades, the disease has been reported by numerous camel-producing countries in Africa and Asia, such as Egypt, Somalia, Sudan, Kenya, Saudi Arabia, and Iraq. The current review provides an overview of the forms of camel mastitis, which can be clinical mastitis characterized by hardening and swelling of the breast, pain on palpation, and visible changes in the colour and texture of the milk or subclinical mastitis refers to the presence of inflammation with no obvious signs and it can be detected by indirect tests such as the California mastitis test (CMT), somatic cell count (SCC), and microbiological examination. Major pathogens of camel mastitis are Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, and Corynebacterium bovis. Regarding the risk factors for camel mastitis, this study provides an overview of the most important risk factors such as severe tick infestation, teat injuries, hygienic milking protocols, and physiological disorders causing mastitis. The use of indirect tests and bacteriological studies as diagnostic tools and their values for detecting camel mastitis will also be reviewed. Based on the above, further epidemiological studies on camel mastitis are needed to have solid scientific data on disease transmission, pathogen characterization, other possible risk factors or diagnostic methods, and the impact of the disease on public health. Proper control strategies should be adopted through early diagnosis, treatment and by avoiding potential risk factors to get good quality milk from camels.

Feasibility of utilising an infrared-thermographic technique for early detection of subclinical mastitis in dairy camels (Camelus dromedarius)

Despite the proven ability of infrared thermography (IRT) technology for early detection of subclinical mastitis in dairy cows/sheep/goats, studies on its diagnostic feasibility in dairy camels are lacking. Sixty-five lactating camels in mid lactation, machine milked twice-daily and managed under intensive conditions were screened to evaluate the feasibility of utilising IRT compared with other routine indicators in detecting subclinical mastitis. Immediately before the morning milking, a portable infrared camera was used to obtain thermograms in duplicate for the front and rear left quarters to determine the udder surface temperature (UST). Thereafter, milk samples from quarters were collected, and processed for California mastitis test (CMT) score and somatic cell count (SCC). In the present study, CMT score was used to define subclinical mastitis and the feasibility of IRT to detect subclinical mastitis was compared with CMT and SCC. According to CMT score, subclinical mastitic udders had an average UST of 1·42 °C greater (P<0·0001) than healthy udders. The relationship between UST and CMT was found to be highly correlated (r=0·77; P<0·001), and UST was linearly increased as the CMT increased [UST (°C)=34·86+0·66×CMT score; R 2=0·65; P<0·001]. Additionally, high correlations were obtained between UST and SCC score (r=0·75; P<0·001) and the relationship between UST and SCC was fitted best to a logarithmic equation [UST, °C=33·39+0·88×Log (SCC, ×103 cells/ml), R 2=0·61, P<0·001]. The cut-off value, sensitivity, specificity and area under the receiver operating characteristics (ROC) curve for UST were 35·15 °C, 0·90, 0·98, and 0·95, respectively, when subclinical mastitis was defined according to CMT score, and were 35·70 °C, 0·89, 0·96 and 0·94, respectively, when categorised according to the obtained SCC threshold (SCC=432 000 cells/ml). In conclusion, IRT, as an indirect non-invasive screening method, was highly feasible for distinguishing subclinical mastitic udders in dairy camels, which is crucial to treat mastitis early and efficiently.

Risk factors associated with prevalence and major bacterial causes of mastitis in dromedary camels (Camelus dromedarius) under different production systems

A cross-sectional study was conducted in desert environment of Jhang (Pakistan) from November 2008 to October 2009 on she-camels kept under pastoralist conditions to determine the prevalence of mastitis, impact of risk factors, and isolate the dominant mastitis-causing bacteria on total of 150 lactating she-camels by using clinical examination and surf field mastitis test. From the 150 she-camels examined, 69 (46%) were positive for mastitis at animal level, 12 (8%) clinical, and 57 (38%) subclinical. Age, parity number, stage of lactation, breed, production system, hygiene of milking process, and presence of lesion on udder/teat were found significantly associated (p<0.05) with the prevalence of mastitis in she-camels. There was the lowest prevalence (33.33%; 15 of 45) of mastitis in she-camels of 5-7 years of age, while the highest (80%; 12 of 15) in the animals aged between 14 to 16 years. Stage of lactation significantly affected (p<0.05) and was found to be associated with the prevalence of mastitis being the highest (54.55%; 18 of 33) during the initial stage of lactation (0 to 1 month) followed by last 2 months (10-12 months) as 54.17% and mid-stages (1-3 and 3-10 months) of lactation as 28.57% (6 of 21) and 37.50% (9 of 24), respectively. According to breed of camels, it was noted that the prevalence of mastitis affected significantly (p<0.05) being the highest in crossbred (Desi × Mareecha) as 51.39% (37 of 72) followed in order by Mareecha and Desi as 43.14% and 37.04%, respectively. Staphylococcus (42.19%) and Streptococcus (15.63%) genera were the dominant isolates identified. Good hygiene in milking process, milking clinically infected she-camels at last, culling chronic mastitis carriers, treating clinically infected she-camels, and dry period therapy could reduce the prevalence of contagious mastitis in the study area.

Exoglycosidase markers of diseases

Exoglycosidases are hydrolases involved in lysosomal degradation of oligosaccharide chains of glycoconjugates (glycoproteins, glycolipids and proteoglycans). In tissues and body fluids, a higher exoglycosidase specific activity is found in N-acetyl-β-hexosaminidase, than β-glucuronidase, α-L-fucosidase, β-galactosidase, α-mannosidase and α-glucosidase. Determination of exoglycosidases (especially N-acetyl-β-hexosaminidase and β-glucuronidase) in body fluids could be an inexpensive, easy to perform and sensitive test for pathological evaluation, as well as in screening and monitoring many diseases, including alcohol abuse, risk of arteriosclerosis, bacterial infections (e.g. Lyme borreliosis), chronic inflammatory processes, such as rheumatoid arthritis and juvenile idiopathic arthritis, asthma, autoimmune hepatitis and primary biliary cirrhosis, as well as cancers.

Udder health problems and major bacterial causes of camel mastitis in Jijiga, Eastern Ethiopia: implication for impacting food security

One hundred and forty-five traditionally kept lactating camels (Camelus dromederius) were examined for mastitis by combination of clinical, mastitis card test and subsequent bacteriological isolation. Clinical and sub-clinical mastitis were prevalent in 8.3% (95%CI = 4.6, 14.4) and 20.7% (95%CI = 14.6, 28.4) of the studied animals, respectively. This gives an overall mastitis prevalence of 29.0% (95%CI = 21.9, 37.2) at animal and 17.9% (95%CI = 14.9, 21.3) at quarter levels. High proportion (33.8%) of lactating camels had blind teats and 5.5% had lesions on udder or teat. Taking clinical mastitis and blocked teats into account, the study revealed that only 57.9% of the camels have four teats for milk production. Out of the 505 quarter milk samples examined, 80 (15.8 %) quarters were positive for indicator paper. Upon subsequent culturing, 68.8% (55 out of 80) of the quarter milk samples yielded bacteria. Staphylococcus, Streptococcus, E. coli and Bacillus species were the major isolates. Mastitis prevalence was significantly (p<0.05) affected by tick infestations, udder lesions, and increased age and parity of the animals. In conclusion, mastitis is a major problem in traditionally managed camels and deserves further attention owning to its potential impact on milk production affecting food security.

Infectious causes of reproductive loss in camelids

Reproductive losses in camelids are due to infertility, pregnancy loss, udder diseases and neonatal mortality caused by a variety of infectious diseases. Uterine infection and abortion represent the major complaint in camelid veterinary practice. The major infectious organisms in endometritis and metritis are E. coli and Streptococcus equi subspecies zooepidemicus. Abortion rates due to infectious diseases vary from 10% to more than 70% in some areas. Leptospirosis, toxoplasmosis and chlamydiosis have been diagnosed as the major causes of abortion in llamas and alpacas. In camels, brucellosis and trypanosomiasis represent the major causes of infectious abortion in the Middle East and Africa. Mastitis is rare in South American camelids. The prevalence of subclinical udder infection in camels can reach very high proportions in dairy camels. Udder infections are primarily due to Streptococcus agalactiae and Staphylococcus aureus. Neonatal mortality is primarily due to diarrhea following failure of passive transfer and exposure to E. coli, rotavirus, coronavirus, Coccidia and Salmonella. This paper reviews the etio-pathogenesis of these causes of reproductive losses, as well as the major risk factors and strategies to prevent their occurrence.

Detection of subclinical mastitis in dromedary camels (Camelus dromedarius) using somatic cell counts and the N-acetyl-beta-D-glucosaminidase test

Somatic cell counts, N-acetyl-beta-D-glucosaminidase (NAGase) activity and the infection status of the udder were determined in quarter milk samples (n = 86) from 22 multiparous, clinically healthy camels, traditionally managed by Bedouin nomads in the Negev desert, Israel. Seventy (81.4%) of the 86 samples examined contained bacteria, of which 35 (40.7%) gave mixed isolations of two or more bacteria, suggesting the existence of subclinical mastitis in the camel herds studied. Sixteen samples (18.6%) yielded no growth of bacteria. Staphylococcus aureus, Micrococcus spp., Bacillus spp., Streptococcus dysgalactiae and Escherichia coli were the main organisms isolated. The somatic cell count (SCC) ranged from 1.01 x 105 to 11.78 x 106 cells/ml. NAGase values were between 41.4 and 372 NAGase units. Quarter milk samples that contained bacteria had significantly (p < 0.01) higher mean values for SCC but the mean NAGase levels were not significantly different for the bacteriologically negative and positive samples. There was a low correlation coefficient (r2 = 0.097) between the SCC and NAGase in the quarter milk samples from which bacteria were not isolated (n = 16) and a low negative correlation (r2 = -0.038) with the samples that contained bacteria (n = 70). The type of bacteria had a significant effect (p < 0.01) on the SCC but not on the NAGase activity. Quarter samples from which Staphylococcus aureus (coagulase positive) was isolated showed the highest mean SCC and this organism is therefore suspected to be the underlying cause of the subclinical mastitis. The SCC gave a better indication of the presence of pathogenic microorganisms in milk samples than did NAGase.