Twenty lactating Beetal goats were divided as Pre-summer group: (n=5) without supplementation and Summer group: (n=20). The latter group was further divided in sub-groups namely Group I: (n=5) Control, no supplementation; Group II: (n=5) supplemented with fenugreek seeds @ 10g/animal/day for 30 days; Group III: (n=5) supplemented with Yea Sacc®1026 @ 2g consisting of 10 billion yeast cells/animal/day for 30 days and Group IV: (n=5) supplemented with fenugreek seeds and Yea Sacc®1026 combination for 30 days. Summer stressed goats exhibited elevated levels of malondialdehyde and reduced the levels of Superoxide dismutase activity, Vitamin E, Vitamin C and reduced glutathione. Supplementation of fenugreek seeds and Yea Sacc®1026 reduced levels of lipid peroxidation and improved the superoxide dismutase activity. Total average milk yield (kg/day) was the highest in group IV (0.988±0.03) followed by groups II (0.889±0.02) and III (0.785±0.012) which was significantly higher as compared to the unsupplemented group I (0.618±0.004).

Among others, methionine residues are highly susceptible to host generated oxidants. Repair of oxidized methionine (Met-SO) residues to methionine (Met) by methionine sulfoxide reductases (Msrs) play a chief role in stress survival of bacterial pathogens, including S. Typhimurium. Periplasmic proteins, involved in many important cellular functions, are highly susceptible to host generated oxidants. According to location in cell, two types of Msrs, cytoplasmic and periplasmic are present in S. Typhimurium. Owing to its localization, periplasmic Msr (MsrP) might play crucial role in defending the host generated oxidants. Here, we have assessed the role of MsrP in combating oxidative stress and colonization of S. Typhimurium. ΔmsrP (mutant strain) grew normally in in-vitro media. In comparison to S. Typhimurium (wild type), mutant strain showed mild hypersensitivity to HOCl and chloramine-T (ChT). Following exposure to HOCl, mutant strain showed almost similar protein carbonyl levels (a marker of protein oxidation) as compared to S. Typhimurium strain. Additionally, ΔmsrP strain showed higher susceptibility to neutrophils than the parent strain. Further, the mutant strain showed very mild defect in survival in mice spleen and liver as compared to wild type strain. In nutshell our results indicate that MsrP plays only a secondary role in combating oxidative stress and colonization of S. Typhimurium.

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