Dairy Production, National Dairy Research Institute, Bangalore 560030, India.
Study was undertaken to assess the digestibility of essential cation minerals viz., Ca2+, Mg2+, Cu2+, Zn2+, Fe2+ and, Mn2+ when electrovalency of mineral supplement was positive or negative. Lactating Deoni cows were divided into 4 groups of 4 each in completely randomized block design and fed 8 KG fresh para grass, ad lib ragi straw and concentrate supplement without mineral mixture (control) or fortified with essential cation (T1) or anion (T2) minerals or both together (T3). The net electrical charge in the mineral mixtures in T1, T2 and T3 were +0.87, –1.55 and –0.64, respectively. DM (p = 0.96), OM (p = 0.96), CP (p = 0.99), Fe2+ (p = 0.98) and Mn2+ (p = 0.83) intakes were not significantly different between CG and TGs. Net charge in T2 affected CP digestibility adversely (p< 0.05). Ca2+ digestibility was apparently (p = 0.29) higher in T2 and T3. Lack of Phosphorus (P–) source in T1 affected the Ca2+ utilization in comparison to T2 and T3. Mg2+ digestibility was higher (P< 0.05) in T2 and T3 than CG and T1. Cu2+ digestibility was not significantly (p= 0.77) different between groups. Zn2+ (p < 0.01), Fe2+ (p < 0.01) and Mn2+ (p < 0.01) digestibility was significantly different between CG and TGs and appeared that the net electrical charge of mineral mixture influenced the digestibility of opposite ions. Study concluded that cation mineral digestibility was better when net electrical charge of mineral mixture was negative.