The impact of different levels of dietary β-carotene to alleviate the effect of mercuric chloride toxicity in Nile tilapia was assessed. Semi-purified diets containing 0, 40, and 100 mg β-carotene kg(-1) dry diet were fed for 21 days, which were subjected to sublethal concentration of mercuric chloride (0.05 ppm). Hematological and biochemical parameters, lipid profile, and antioxidant response were examined. All hematological parameters of tilapia fish starting from second week of toxicity were significantly decreased. A significant increasing trend in liver enzymes (ALT and AST) were observed parallel to the time of toxicity and peroxide radicals (MDA) appearing significantly increased in toxicated group without carotene supplement, although carotene supplementation return all parameters within the control levels. Mercury accumulated significantly in fish liver and white muscles in toxicated group while it showed a significant reduction in dietary β-carotene-treated group. Overall, it can be used as immunostimulant and alleviate the suppression effect resulted from immune depressive stressful condition in farmed Nile tilapia.

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Since lactoferrin is acute phase protein and has an exceptional role in defense mechanism of mammary gland, it is considered a candidate gene for mastitis susceptibility in dairy cattle. In this study, blood samples were collected for DNA extraction from fifty Holstein dairy cows in the third lactation season reared under Egyptian conditions assigned into three groups mastitis (n=15), subclinical mastitis (n=20) and healthy (n=15) based on California mastitis test. Moreover biochemical markers for inflammation were determined to detect severity. PCR amplification of a segment of 6th intron of lactoferrin gene yielded a fragment of 301-bp in all animals under study. For revealing polymorphism, DNA sequencing was done for PCR products of lactoferrin gene (301-bp) in only five healthy (resistant) and five affected animals. Results indicated that, association between biochemical data and affections. The PCR-DNA sequencing genetic assessment identified twelve SNPs in the bovine lactoferrin gene and there was association between these identified SNPs and mastitis susceptibility, where ten nucleotide sequence variations for one of the healthy animals were obtained with A166T, T185A, T200C, G230C, A239G, T251G, A254C, A272C, T273C and A296G SNPs (submitted to GenBank with accession number gb|KT159457|. On the other hand, two nucleotide sequence variations for two of the affected animals were obtained with A100G and T275A SNPs. Consequently, the identified SNPs in the bovine lactoferrin gene can be used as marker-assisted selection (MAS) to predict, improve mastitis resistance and minimize incidence of mastitis infection in Holstein dairy cows.

Relatedness between single nucleotide polymorphisms in IL8 and TLR4 genes and digital dermatitis resistance/susceptibility was investigated in seventy Holstein dairy cows. Animals were assigned into two groups, affected group (n = 35) and resistant group (n = 35) based on clinical signs and previous history of farm clinical records. Blood samples were collected for DNA extraction to ampliy fragments of 267-bp and 382-bp for IL8 and TLR4 genes, respectively. PCR-DNA sequencing revealed three SNPs in each of IL8 and TLR4 genes. The identified SNPs associated with digital dermatitis resistance were C94T, A220G, and T262A for IL8 and C118T for TLR4. However, the G349C and C355A SNPs in TLR4 gene were associated with digital dermatitis susceptibility. Chi-square analysis for comparison the distribution of all identified SNPs in both IL8 and TLR4 genes between resistant and affected animals showed no significant variation among the identified SNPs in IL8 gene. Meanwhile, there was a significant variation in case of TLR4 gene. As a pilot study, the present results revealed that identified SNPs in IL8 and TLR4 genes can be used as a genetic marker and predisposing factor for resistance/susceptibility to digital dermatitis in dairy cows. However, TLR4 gene may be a potential candidate for such disease.

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