عنوان مقاله [English]
Background and Objectives: Pro- inflammatory cytokines are small proteins that are released by different tissues and cause an inflammatory condition in body. Conjugated linoleic acid (CLA) is a common name for fatty acids with 18-carbon and a conjugated double bond. Conjugated linoleic acid can affect pro-inflammatory cytokines production. Since pro-inflammatory cytokines can affect different physiological processes, this study investigated effects of conjugated linoleic acid supplementation during transition period on gene expression of pro-inflammatory cytokines in mammary gland, uterus and subcutaneous fat of Holstein cows.
Materials and Methods: Twenty-four cows with body condition scores of 3.2±0.20 (SEM±mean) and lactation number of 3.2±1.80 were allocated to four treatments (six heads per treatment): feeding palm oil (75g/d) from -21 d to +21 d (C21) or +42 d (C42) relative to parturition, feeding rumen protected CLA (75g/d) from -21 d to +21 d (CLA21) or +42 d (CLA42) relative to parturition. Rumen protected CLA provided 7.5 g/d each of trans-10, cis-12 CLA and cis-9, trans-11 isomers. Tissue samples were taken from mammary gland, uterus and subcutaneous fat at 21 and 42 days postpartum. Mammary gland samples were taken from the sampling site in rear udder, 6-8 cm bottom to udder and skin junction and 3 cm of udder cleft using a medical semi-automatic sampling device. Uterus samples were taken by passing a sampling device through cervix and conducting uterus body via rectum. By making an incision through the skin of around pin, subcutaneous fat samples were taken. Expression of tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) enzyme and toll like receptor-4 (TLR-4) were measured by real time-PCR.
Results: Feeding rumen protected CLA during transition period decreased TNF-α gene expression in mammary gland (P˂0.05). In mammary gland, effect of time and interaction of time in treatment were nonsignificant for TNF-α. Conjugated linoleic acid increased expression of COX-2 gene in uterus of CLA42 cows (P˂0.01). In uterus, effect of time was significant for COX-2 (P=0.05). Feeding rumen protected CLA during transition period significantly increased COX-2 gene expression, but had no effects on gene expression of TNF-α and TLR-4 in subcutaneous fat.
Conclusion: Results of this experiment showed that adding CLA supplementation to dairy cow’s ration during transition period can alter expression of some pro-inflammatory cytokine genes in mammary gland uterus and subcutaneous fat. Results of this study provide preliminary findings that can be used in ongoing mechanistic studies investigating CLA effects on some tissues in dairy cows.