Relation of Calcium Activity in Milk and Milk Production of Holstein Cows in Hot Season

  • Tanaka, Masahito (National Agricultural Research Center for Kyushu Okinawa Region) ;
  • Suzuki, Tomoyuki (National Agricultural Research Center for Kyushu Okinawa Region) ;
  • Kotb, Saber (Faculty of Veterinary Medicine, Assiut University) ;
  • Kamiya, Yuko (National Agricultural Research Center for Kyushu Okinawa Region)
  • Received : 2011.01.04
  • Accepted : 2011.02.21
  • Published : 2011.10.01


The content of Ca in milk exceeds the typical saturation level of Ca salts, which is necessary for neonate growth. This calcium is distributed between the casein micelles in the colloidal and aqueous phases. Information on the properties of calcium activity in the aqueous phase is limited compared with that on the properties of bound or sequestrated calcium. The objectives of this study were to evaluate the changes in calcium activity in fresh milk using an ion-selective electrode and to assess the relationship between calcium activity and milk production in hot season. Milk samples collected from 10 cows at the National Agricultural Research Center for Kyushu Okinawa Region in June to October (Min-Max: 7.2-$35.2^{\circ}C$, 24.3-100% RH) were analyzed on total calcium concentrations and calcium activity. We observed that the rectal temperature of the cows increased according to elevation of ambient temperature but that the pH of the collected milk ($6.61{\pm}0.01$ (Mean${\pm}$SEM)) was not significantly influenced by rectal and ambient temperature. Total calcium concentrations and calcium activity in fresh milk decreased in July (Min-Max: 21.1-$33.5^{\circ}C$, 48.9-100.0% RH) compared with the values after August (Min-Max: 18.1-$35.0^{\circ}C$, 26.5-96.2% RH) (p<0.05); however, there was no significant correlation between the two parameters. The ratio of calcium activity to total calcium concentration decreased after August compared with the values in June and July (p<0.05). The calcium activity in fresh milk was positively correlated with milk yield (r = 0.45, p<0.01) and negatively correlated with milk lactose content (r = -0.53, p<0.01). These results suggest that the calcium activity in milk could be affected by ambient temperature and might be associated with milking production in hot season.


  1. Allen, J. C. and M. C. Neville. 1983. Ionized calcium in human milk determined with a calcium-selective electrode. Clin. Chem. 29:858-861.
  2. Farrell, H. M. 1988. Physical equilibria: proteins. Page 461 in Fundamentals of Dairy Chemistry, 3rd edn. NP. Wong, ed VanNostrand Reinhold, NY, USA.
  3. Griffin, M. C. A., R. L. Lyster and J. C. Price. 1988. The disaggregation of calcium-depleted casein micelles. Eur. J. Biocem. 174: 339-343.
  4. Holt, C., D. G. Dalgleish and R. Jenness. 1981. Calculation of the ion equilibria in milk diffusate and comparison with experiment. Anal. Biocem. 113:154-163.
  5. Holt, C. and R. Jenness. 1984. Interrelationships of constituents and partition of salts in milk samples from eight species. Comp. Biochem. Physiol. 77:275-282.
  6. Jenness, R. 1979. Comparative aspects of milk proteins. J. Dairy Res. 46:197-210.
  7. Kadzere, C. T., M. R. Murphy, N. Silanikove and E. Maltz. 2002. Heat stress in lactating dairy cows: a review. Livest. Prod. Sci. 77:59-91.
  8. Kamiya, M., Y. Iwama, M. Tanaka and S. Shioya. 2005. Effects of high ambient temperature and restricted feed intake on nitrogen utilization for milk production in lactating Holstein cows. Anim. Sci. J. 76:217-223.
  9. Kamiya, Y., M. Kamiya and M. Tanaka. 2006. Effects of forage-to concentrate ratio in prepartum diet on the dry matter intake and milk yield of periparturient cows during hot weather. Anim. Sci. J. 77:63-70.
  10. Kume, S., S. Takahashi, M. Kurihara and T. Aii. 1989. The effects of a hot environment on the major mineral content in milk. Jpn. J. Zoothech. Sci. (Jpn) 60:341-345.
  11. Kume, S., S. Takahashi, M. Kurihara and T. Aii. 1990. The effects of heat stress on milk yield, milk composition, and major mineral content in milk of dairy cows during early lactation. Jpn. J. Zootech. Sci. 61:627-632.
  12. Landenson, J. H. and G. N. Bowers, Jr. 1973. Free calcium in serum. 1. Determination with the ion-specific electrode, and factors affecting the results. Clin. Chem. 19:565-574.
  13. Neville, M. C. and M. Peaker. 1981. Ionized calcium in milk and the integrity of the mammary epithelium in the goat. J. Physiol. 313:561-570.
  14. Neville, M. C., R. P. Keller, C. Casey and J. C. Allen. 1994. Calcium partitioning in human and bovine milk. J. Dairy Sci. 77:1964-1975.
  15. Neville, M. C. 2005: Calcium Secretion into milk. J. Mammary Gland Biol. Neoplasia 10:119-128.
  16. Reist, M., D. Erdin, D. von Euw, K. Tschuemperlin, H. Leuenberger, Y. Chilliard, H. M. Hammon, C. Morel, C. Philipona, Y. Zbinden, N. Kuenzi and J. W. Blum. 2002. Estimation of energy balance at the individual and herd level using blood and milk traits in high-yielding dairy cows. J. Dairy Sci. 85:3314-3327.
  17. Pitelka, D. R., B. N. Taggart and S. T. Hamamoto. 1983. Effects of extracellular calcium depletion on membrane topography and occluding junctions of mammary epithelial cells in culture. J. Cell. Biol. 96:613-624.
  18. Sevi, A., M. Albenzio, R. Marino, A. Santillo and A. Muscio. 2004. Effects of lambing season and stage of lactation on ewe milk quality. Small Rumin. Res. 51:251-259.
  19. Silanikove, N., F. Shapiro and A. Shamay. 2003. Use of an ion-selective electrode to determine free Ca ion concentration in the milk of various mammals. J. Dairy Res. 70:241-243.
  20. Stelwagen, K., V. C. Farr, S. R. Davis and C. G. Prosser. 1995. EGTA-induced disruption of epithelial cell tight junctions in the lactating caprine mammary gland. Am. J. Physiol. 269:R848-R855.