The effect of mineral and vitamin injections in late pregnancy on feed intake, milk production and composition, colostrum quality and metabolic abnormalities

Background and Objectives:
One of the most important challenges in the life of dairy cows is their passage through the stressful physiological phase of transition. On the other hand, late pregnancy is associated with a decrease in dry matter intake and an increase in energy requirements, which in turn causes a negative energy balance in the animal. This negative energy balance also increases oxidative stress and reactive oxygen species, which reduce immune resistance and predispose the animal to postpartum diseases, reduced milk production and the risk of culling. Minerals and vitamins are essential as antioxidants to improve the immune system in dairy cows, and the consumption of minerals and vitamins above the predicted requirements, especially during stressful and sensitive conditions, can positively affect the productivity of dairy cows. Therefore, an adequate supply of vitamins and minerals is important to ensure an optimal transition from pregnancy to lactation.
Material and Methods: The present study was conducted to investigate the effect of injecting some mineral elements and vitamins in late pregnancy of cows on feed intake, milk production and composition, colostrum quality and metabolic abnormalities using 32 pregnant cows in the transition period in a completely randomized design with 4 treatments and 8 replications. The experimental treatments included: 1) control group (no vitamin and mineral supplement injection), 2) treatment receiving injectable vitamin supplement, 3) treatment receiving injectable mineral supplement and 4) treatment receiving injectable vitamin and mineral supplement. Supplement injections were performed 28 days before calving. Vitamin supplements included vitamins A, D3, E, B1, B2, B3, B6, B12, C and mineral supplements included calcium, copper, magnesium and phosphorus. The injection dose of mineral supplements was 100 ml and the injection dose of vitamin supplements was 20 ml. To determine the amount of dry matter consumed daily before the new feed was fed, the afterfeed was collected and weighed. The occurrence of metabolic abnormalities including clinical mastitis, retained placenta, dystocia, and lameness in different treatments was recorded and the number of affected animals was expressed.
Results: The results of the effect of mineral and vitamin injections in late pregnancy on body condition score and dry matter intake of cows are reported Mineral and vitamin injections had no effect on body condition score 21 days before calving, day of calving, and postpartum, changes in body score 21 days before calving to day of calving, changes in body score from day of calving to 21 days after calving, and dry matter intake before calving, day of calving, and postpartum of cows (P>0.05). Simultaneous injection of minerals, vitamins, and minerals and vitamins increased the percentage of non-fat solids and the amount of lactose, protein, total solids, non-fat solids, and decreased urea nitrogen and the number of somatic cells (P<0.05). There was no difference in milk production, percentage of fat, lactose, protein, total solids, and the amount of fat and lactose, and somatic cell score between the treatments receiving minerals and vitamins and the control group. Mineral and vitamin injection increased the birth weight of calves and reduced the time of placental expulsion in cows. but had no effect on the length of gestation and rectal temperature of cows (P>0.05). Mineral and vitamin injection reduced the number of animals with mastitis, dystocia, lameness, and retained placenta; so that dystocia was reported in the mineral and mineral supplement + vitamins groups, mastitis in the vitamins group, and retained placenta was reported to be zero in vitamins, minerals, and vitamins + minerals groups.
Conclusion: Therefore, considering the improvement of productive and reproductive performance of cows, injection of minerals and vitamins is recommended for cows in the late pregnancy period.