July 9 - 15, 20

In dairy nutrition, calcium (ca) and phosphorus (P) are considered together as deficiency or an excess of one will interfere with the proper utilization of the other. In young animals and humans, shortage of Ca, P, or vitamin D results in rickets, and in the adult or more mature animal, osteomalacia.

Ca and P are two most abundant mineral elements in the animal body. They are frequently found in insufficient quantities in common feedstuffs to meet requirements of livestock. Phosphorus deficiency is predominantly a condition of grazing ruminants, especially cattle, whereas Ca deficiency is more a problem of animal fed mostly on concentrates.

Significant seasonal changes in concentrations of different minerals can be observed in blood serum of grazing cows. There is need to ascertain the status of Ca and P in different canal irrigated districts of Punjab having highest population density of livestock.

Livestock provides protein of more biological value to human population in the form of milk, meat, eggs, and other by products.

Increased environmental concerns and regulations have stimulated renewed interest in phosphorus in dairy cattle rations. The challenge is to design rations with adequate P to meet the needs of the cow while minimizing P excretion to the environment. Environmental regulations, which limit the quantity of P applied to land, are either in place or being considered.

It has been indicated that P accounts for more than 50 per cent of the cost of typical vitamin mineral mixes are used on dairy farm. Thus, there is rationale from both economic and environmental considerations to minimize feeding P in excess of requirements.

Keeping in view the situation, a series of experiments was executed. In first experiment status of Ca and P in livestock of ten districts of canal irrigated zones of Punjab, based on water, feedstuffs, soil, and blood analyses were done. Results of the study showed imbalances in minerals status of livestock. This variation in Ca and P profile requires minerals supplementation especially Ca and P according to area, species, and physiological status of the animals.

Variation in minerals status of livestock might be due to different feeding practices, difference in soil fertility, environment, stage of maturity and species of fodder crops. The foremost advantage of the study was the provision of guidelines in formulating the premixes and balanced feed for livestock in the study area to initiate prophylactic measures against factors that are badly taxing the current productivity of livestock of various categories in future.

In second experiment, effect of varying dietary levels of Ca and P on bioavailability of macro and micro-minerals in lactating Sahiwal cows was determined. For this purpose, six rations were prepared with varying levels of Ca and P. It was observed there was an increased level of Ca and decreased absorption of Zn, K and Mg. High levels of P and Ca decreased absorption and increased their excretion casing environmental pollution.

In third experiment, effect of varying dietary levels of Ca and P on efficacy of exogenous phytase in lactating Sahiwal cows was studied. In this experiment, 12 rations were prepared. Out of 12 rations, six were supplemented with 500 FTU phytase/kg of DM.

It was concluded that addition of exogenous phytase decreased P excretion and increased its absorption significantly. It also increased absorption of Ca and Zn to some extent. It was obvious that by adding exogenous phytase, we may decrease phosphorus excretion helping in protecting environment from this pollutant.

Before planning to supplement the dairy animals with Ca and P, feed and mineral status must be known. Addition of proper dose of Ca and P not only saved cost but also decreased environmental pollution. Addition of increased level of these minerals also interfered with absorption of other macro-minerals and micro-minerals. Use of exogenous phytase can be a tool to decrease the phosphorous excretion.