Effect of LNA integration on endocrine and metabolic parameters in dairy cattle

In a field trial the effect of long term supplementation of different levels of estruded linssed and energy levels on milk yeld and plasma concentrations of insulin, T3,cortisol, leptin, glucose and non esterified fatty acids (NEFA) in dairy cow in early lactation, were evaluated. Fifth seven italian holstein fresian cows reared in Parmigiano Reggiano cheese area, homogeneous for lactation number, days in miilkings (DIM) (41±12d), BCS (3.17±0.14) in productive level in the previous lactations, were allotted into three experimental groups, in different farms, with similar management system (Control group - C 1.45 Mcal NEI/Kg DM, 280 g/d Omega-Lin® - Mignini &Petrini 0280; 1.51 Mcal NEI/Kg DM, 450 g/d Omega-Lin® - Mignini &Petrini 0450; 1.56 Mcal NEI/Kg DM) and feed isonitrogenous TMR diets. Omega-Lin® contained 70% of exstruded linseed. Blood samples were taken by coccigeal vein and blood parameters evaluated. Fixed effect of diet, parity and hear within diet were tested. Parity showed a significant effect only for milk yeld and T3, while diet influenced significantly milk yield, T3, leptin and NEFA. Milk yield was higher in 0450 group compared to the control one (43.61 vs 35.51: P<0.01). T3 showed the highest level in 0450 group if compared with C group (1.32 nmol/l vs 1.07 nmol/l: P<0.01) while 0280 group showed an intermediated level. NEFA as indicators of body lipids mobilization showed the highest in C group (0.50 mmol/l) and lower in 0280 group (0.29 mmol/l) (P<0.01) while 0450 showed an intermediated level. Opposite results were found for leptinwhich showed the highest level in 0280 group and the lowest in C group (4.08 ng/mL vs3.08 ng/mL: P<0.05) while 0450 group showed an intermediate level. No significant differences were found in the other parameters although cortisol and insulin are key players in the control of intermediary metabolism and glucose as indicator of energy balance. In conclusion leptin, T3, NEFA levels in 0450 group put in eveidence a better energy utilization for milk yield although the trend of these parameters showed in 0280 group should be explained by a probably different genetic valueof the cows among farms. Further analyses will be desiderable.