Effect of injection of vitamin C and copper on milk production and composition, and body condition score of transition dairy cows under heat stress

Transition period is the period between 3 weeks before and 3 weeks after parturition which is one of the most critical physiological stage in dairy cows. Decreasing dry matter intake (DMI) and negative energy balance (NEB) potentially weakens immunity system and increases higher incidence of metabolic and infectious diseases such mastitis. High temperature in summer results in heat stress which subsequently reduce DMI and changes metabolic reaction in lactating dairy cows. Consumption of some vitamins and minerals could reduce negative effects of transition period and heat stress such as vitamin C and copper. The aim of this experiment was to study the effect of injection of vitamin C and copper to transition dairy cows on milk production and composition and body condition score (BCS), DMI in calving day and blood cells in summer season.

In this experiment twenty multiparous (second parity, with 603.18 ± 51 kg average body weight) and twenty multiparous (third and fourth parity, 669.05 ± 53 kg average body weight) Holstein cows were used in a completely randomized block design with 2*2 factorial arrangement. Experiment extended from 40 d before expected calving till 90 d after calving. Experimental treatments consisted of control (injection of 7 ml of NaCl % 0.9), Vitamin C (injection of 25 mg vitamin C solution/kg body weight), Copper (injection of 75 mg copper solution/day) and Vitamin C-Copper (simultaneous injection of 25 mg vitamin C solution/ kg body weight and 75 mg copper solution/day). Solutions were injected on 20 and 40 d before expected calving, calving day and 20 d after calving. Maximum temperature-humidity index during the experiment was between 68.27 to 78.20. Body condition score (BCS) changes, DMI in calving day, milk production and composition and blood cells were evaluated.

Results showed that BCS, DMI in calving day, milk production and composition on d 7, 30, 60 and 90 after calving and cell blood count except of neutrophil count were not influenced by simultaneous injection of vitamin C and copper solutions. Blood neutrophil count on d 20 before expected calving did not affected by injection of vitamin C while as vitamin C injection enhanced blood neutrophil count on calving day, 10, 20 and 30 d after calving (P<0.05). Copper solution injection in compare to lack of injection tended to less changes on BCS form calving day till 30 d after calving (P=0.06). Red blood cell counts on calving day in cows receiving copper solution injection were greater in compare to lack of injection (P<0.05).

Although, individual injection of vitamin C and copper to transition dairy cows resulted in some changes in blood cell counts but simultaneous injection of vitamin C and copper to heat loaded transition dairy cows had no considerable effect on milk composition and production of the first 90 d calving.