Exploring the Effects of Oral Calcium Bolus Supplementation on Serum Minerals and Energy Balance Indicators in Simmental Cows Fed a Prepartum Anionic Diet

Abstract

Simple Summary Calcium deficiency around calving is one of the most common problems in dairy cows, and farmers often use oral calcium boluses to prevent it. In this study, we tested a calcium bolus that contained three different calcium sources and vitamin D in Simmental cows, which are a dual-purpose breed. All cows were fed a special diet before calving to help them use calcium more efficiently, and at calving, their blood calcium levels were already normal. Half of the cows received two calcium boluses, one at calving and another 24 h later, while the other half did not receive any boluses. Blood samples were taken during the first two days and again up to two weeks after calving to measure calcium, phosphorus, magnesium, glucose, and ketone bodies. The results showed that the calcium boluses caused only a small and short-lived rise in blood calcium, and there were no clear differences between treated and untreated cows for any of the measured blood values. This study suggests that, in well-managed Simmental herds already receiving proper pre-calving diets, extra calcium supplementation may not be necessary when cows have normal calcium levels at calving. These findings can help farmers use supplements more effectively and avoid unnecessary costs.Abstract Calcium disorders remain a major challenge during the transition period of dairy cows, and oral calcium supplements are widely used to prevent postpartum hypocalcemia. This study evaluated the effects of administering an oral Ca-bolus containing calcium sulfate, acetate, and formate on postpartum mineral status and energy balance in multiparous Simmental cows. Twenty cows (mean parity 3.5 +/- 0.51) were fed a prepartum diet with a negative dietary cation-anion difference (DCAD) and enrolled at calving if body condition score was between 3.0 and 3.5 and urine pH ranged from 6.2 to 6.8 during the wk before parturition. Animals were blocked by parity and randomly assigned to a control group (n = 10) or to a treatment group (n = 10) receiving two oral boluses (each 175 g; 45.14 g calcium plus 40,250 IU vitamin D3), administered immediately after calving and 24 h later. Blood samples were collected up to 48 h postpartum for calcium, phosphorus, and magnesium analyses, and up to 14 d postpartum for glucose and beta-hydroxybutyrate. Both groups were normocalcemic at calving, and no significant treatment effects were detected for any parameter at any time point. However, a short-lived numerical increase in calcium was observed 6 h after bolus administration. These results suggest that additional oral Ca supplementation may not be required in well-managed Simmental cows receiving a prepartum negative DCAD diet.