Risk factors associated with subclinical mastitis and its effect on physico-mineral features of camel milk

This study was carried out to determine the risk factors implicated in camel subclinical mastitis as well as the physico-mineral features of camel milk, there by examining the effect of this disease on those parameters. Milk samples were obtained from 125 lactating multiparous she-camels (aged 10-12 years) during early lactation from December 2020 to April 2021. The samples were screened for the presence of subclinical mastitis using the somatic cell count (SCC) test. In total, 73 (58.4%) samples showed the presence of subclinical mastitis, whereas the remaining 52 (41.6%) samples showed negative results for subclinical mastitis. Standard methods were used to appreciate the pH and mineral composition of the milk samples, such as Ca, Na, Cl, and K contents. In camels, unhygienic udder condition was identified as the major risk factor for the incidence of subclinical mastitis. Calf mortality and increased herd size were associated with a higher prevalence of subclinical mastitis. Tick infestations were also significantly associated with increased disease risk. Use of antisuckling devices, increase in milk yield, and weakness of body condition were identified as main risk factors and were primarily associated with the disease. However, udder lesions and deformities, milking frequency, and owner visits had no significant influence on the occurrence of subclinical mastitis. The overall mean pH value was 6.54 ± 0.01 and the mean values of Ca, Na, Cl, and K contents were 148.24 ± 2.55, 53.83 ± 1.52, 124.99 ± 1.80, and 240.22 ± 3.80 mg/100 g, respectively. When the level of milk from healthy animals and that from camels with subclinical mastitis (SCC > 2.4 × 10⁵) were compared, it showed that Na and Cl contents were significantly increased (p < 0.05) with the increase in SCC (56.52 vs.50.07 and 128.26 vs.120.40 mg/100 g, respectively). In contrast, there were no notable changes (p > 0.05) in the Ca, K, and pH values. In conclusion, udder hygiene, calf mortality, herd size, tick infestations, use of antisuckling devices, higher milk yield, and body condition were identified as the major risk factors that predispose the camels to subclinical mastitis. Furthermore, an increase in the Na and Cl levels in camel milk was observed along with udder inflammation. Consequently, the elevated Na and Cl levels in milk can be a sign of subclinical mastitis in camels.