Effect of the administration of a ruminal bolus containing 1,25-dihydroxyvitamin D3 glycosides from Solanum Glaucophyllum on blood calcium levels, hypocalcaemia, production performance, health status and fertility rate in lactating dairy cows

Abstract

The aim of the study was to evaluate the efficacy of a bolus containing natural glycosides extracted from Solanum glaucopyllum, rich in 1,25-dihydroxyvitamin D3 glycosides (1,25(OH)2D3), in the prevention of subclinical hypocalcaemia, and of its correlated health and production problems in transition dairy cows.
A total of 60 pregnant Holstein Friesian cows were balanced for parity and assigned to one of the two study groups: Control (15 cows) and Treatment (45 cows), receiving a bolus containing either 0 or 500 μg of 1,25(OH)2D3 extracted from S. glaucophyllum. Blood total (tCa) and ionized (Ca2+) calcium, phosphorus (P) and magnesium (Mg) were evaluated at different time points.
Data related to health status, production and reproductive efficiency were evaluated, both considering the two entire populations and separately for healthy and sick cows that undergone to retained placenta and metritis.
The treatment has led to a significant increase in the blood tCa (2.26 mmol/L) and Ca2+ (2.19 mmol/L) at calving, compared to prepartum (respectively 2.05 and 1.98 mmol/L), while in the Control there was a significant decrease in both blood tCa and Ca2+ (respectively, 1.76 mmol/L and 1.74 mmol/L at calving vs 2.12 and 2.02 mmol/L prepartum) (P<0.05), with also a significant difference at calving between the two groups (P<0.05). No significant differences were found in terms of Mg and P concentrations.

The treatment has led to a significantly lower incidence of subclinical hypocalcaemia at calving (13.33% vs 80.00% considering tCa, and 24.44% vs 86.67% considering Ca2+) (P<0.0001) and after 24h (35.56% vs 73.33% considering tCa) (P=0.009). The treatment increased significantly Ca2+ levels at calving (1.95 vs 1.56 mmol/L) (P<0.05) in sick cows. The incidence of metritis was significantly reduced by the treatment (2.22 vs 20.00%) (P<0.05). Milk production (27.93 vs 25.70 L/head/day), dry matter intake (DMI) (19.11 vs 18.30 kg/head/d dry matter) and feed conversion rate (FCR) (1.46 vs 1.40), in the first 15 days of lactation (DIM), and days to first heat (36.55 vs 41.86 days) and day to pregnancy (97.51 vs 107.47 days) were improved in treatment group compared to Control (P<0.05).
Similarly, also in sick animals, milk production (treatment 23.48 vs 19.22 L/head/d in Control), DMI (15.29 vs 13.86 kg dry matter/ head/d) and FCR (1.53 vs 1.39), in the first 15 DIM, and days to first heat (53.00 vs 67.66 days), and days to pregnancy (125.50 vs 153.67 days) were improved by the treatment (P<0.05).
The results of the present study highlight a potential effectiveness of boluses containing 1,25(OH)2D3 extracted from S. glaucophyllum in reducing the incidence and severity of hypocalcaemia in transition dairy cows, with positive effect of both animal welfare and productivity.