Abstract
A study was conducted to determine the calcium nutrition status of different classes of grazing sheep during two different seasons on a farm located in southern Punjab (Pakistan). A complete free-choice supplement was available to all animals throughout the year. Soil, forage, feed, water, and animal samples like plasma, milk, faeces, and urine from lactating, plasma, faeces, and urine from nonlactating, and that 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 in all classes of sheep, and milk in lactating sheep were affected by the seasonal fluctuations. While the marginal deficient levels of calcium in lactating sheep in summer and moderately deficient plasma calcium level in winter was found. While in non-lactating sheep plasma calcium was in moderate deficient level in winter and marginally deficient level in summer. In male sheep, plasma calcium level in summer was 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 calcium concentrations were above the critical level during both seasons and showed a positive association between them. The feed and forage calcium collectively was sufficiently above the required range for ruminants, but was found ineffective in elevating the plasma calcium levels in all classes of animals showing the low bioavailability in spite of high concentration in the diet. From these analyses, it would suggest that the calcium status of grazing sheep in this specific region needs supplementation with specifically tailored mixture containing calcium with high bioavailability rather than high calcium contents showing antagonism.
