Seasonal variation of calcium in soil-plant-animal system at sheep ranch, Punjab,Pakistan

A study was conducted to determine the calcium nutrition status of differentclasses of grazing sheep during two different seasons on a farm located in southernPunjab (Pakistan). A complete free-choice supplement was available to all animalsthroughout the year. Soil, forage, feed, water, and animal samples like plasma, milk,faeces, and urine from lactating, plasma, faeces, and urine from non- lactating, andthat of plasma and faeces from male animals were taken eight times during the year(four times in each season). The calcium concentrations of forage, feed and plasma inall classes of sheep, and milk in lactating sheep were affected by the seasonalfluctuations. While the marginal deficient levels of calcium in lactating sheep insummer and moderately deficient plasma calcium level in winter was found. While innon-lactating sheep plasma calcium was in moderate deficient level in winter andmarginally deficient level in summer. In male sheep, plasma calcium level in summerwas marginally deficient while plasma calcium during winter was moderately deficient.Plasma calcium in all animals was not affected by the physiological state and gender,as it was overwhelmingly deficient in all classes of sheep. Soil and forage calciumconcentrations were above the critical level during both seasons and showed apositive association between them. The feed and forage calcium collectively wassufficiently above the required range for ruminants, but was found ineffective inelevating the plasma calcium levels in all classes of animals showing the lowbioavailability in spite of high concentration in the diet. From these analyses, itwould suggest that the calcium status of grazing sheep in this specific region needssupplementation with specifically tailored mixture containing calcium with highbioavailability rather than high calcium contents showing antagonism.