The effects of using different glucose precursors on metabolic diseases and lactation performance in dairy cows

This study was carried out to compare the effects of glucose precursors on milk yield and composition, metabolic diseases, blood parameters, reproductive parameters, body condition score and stool score, which are used against the negative energy balance problem encountered in dairy cattle in the transition period. In the study, 60 Holstein breed dairy cows that gave at least one birth were used as animal material. The animals were divided into 3 groups and each group consisted of 20 animals. No application was applied to the animals in the control (K) group during the trial. The animals in the glycerol (G) group were given 1 meal a day during the trial, 450 ml orally after the morning feeding with a pump. The Propylene Glycol (PG) group was given 300 ml of PG in the same way. Milk yield of the animals was monitored daily during the experiment. Milk samples were collected from all cattle for two consecutive days every week until the 100th day of lactation and milk analyzes were performed. Blood samples for metabolic profile tests such as glucose, beta hydroxy butyric acid (BHBA) and non-esterified fatty acid (NEFA) were collected prenatally at -1., 0., 1., 2. and 3. weeks, respectively, and analyzed with commercial kits. During the study, body condition score, stool score, fever, discharge control, involution follow-up, lameness scoring were performed from the cows every week. SPSS package program was used for statistical analysis and comparisons of NEFA, glucose, BHBA, scoring (body condition score, stool score, uterine discharge score, uterus involution score), body temperature, insemination, milk yield and milk composition data were performed with ANOVA, while Tukey HSD has been selected. There was no difference between the groups in terms of BHBA, NEFA and glucose levels of blood samples taken from cows and stool scores, body condition scores, vaginal discharge and uterine discharge. However, the milk yield of cows in the K (35.06 L/day) group was 1 L higher than the G (34.18 L/day) group and 1.5 L higher than the PG (33.46 L/day) group (P<0.05). On the other hand, milk fat was higher in PG group cows (3.67%) than K (3.44%) and G (3.46%) groups (P<0.05). However, the milk proteins of the K (3.32%) group cows were found higher than the PG (3.15%) group. According to the results obtained from the study, milk yield and milk protein were found to be higher in the group K, which was not applied at all, compared to the G and PG groups, and differences were found between the groups in terms of milk fat. Therefore, the behavior of glucose prodrugs such as G and PG especially on the rumen needs to be investigated further.