Association of Milk De Novo Fatty Acid Proportion of the First Week Postpartum With Productivity and Plasma IGF‐1 and GLP‐1 Concentrations in Dairy Cows

Immediate postpartum analysis of milk fatty acid (FA) profiles using Fourier transform infra-red spectrometry (FTIR) may be a non-invasive and simple analytical tool for predicting milk production, health problems and reproductive performance. This study evaluated the relationship between milk de novo fatty acid (FA) proportions at the 1st week postpartum and the pre-and postcalving blood metabolic markers, milk yield, health and reproduction performance after calving. Sixty-five Holstein cows were assessed, and blood samples were collected 3 and 1 weeks before the predicted calving date, on the calving day, and Weeks 1 to 12 of lactation. Milk samples were collected from each cow, and using the 25th and 75th percentiles of milk de novo FA proportion in the 1st week postpartum, the cows were classified into high (HD), medium (MD), and low (LD) de novo groups. The milk de novo FA proportions were ≤ 21.2, 21.3-28.4 and ≥ 28.5 g/100 g FA for the LD, MD and HD groups, respectively. The dystocia score was higher in the LD group than in the HD group; however, no differences were observed between the groups for milk yield, prevalence of postpartum disease, or removal. For reproductive performance, fewer cows were pregnant within 150 days in the LD group compared to those in the HD and MD groups. The LD cows showed higher serum concentrations of nonesterified fatty acids (NEFA) and β-hydroxy butyrate (BHBA) and exhibited lower concentrations of glucose, Mg, and glucagon-like peptide (GLP)-1 than the HD cows after calving. The LD cows showed a decrease in plasma insulin-like growth factor-1 (IGF-1) concentration from 1 week before the predicted calving date and were lower than that of the HD cows throughout lactation. These results indicate that milk de novo FA during the first postpartum stage is a noninvasive tool that can be used as an indicator of a transition dairy cow's nutritional status. Furthermore, IGF-1 may be an earlier predictor than NEFA or BHBA, and GLP-1 could also be a useful and novel marker.