Abstract:
REPRODUCTION STATUS AND BLOOD PHOSPHORUS LEVEL IN CATTLE E. TELENI* and R.M. MURRAY* Phosphorus deficiency is widespread throughout the cattle country of Queensland. The element is cheap and easy to supply to cattle and any resultant increase in productivity, especially in fertility, would be of great value to the grazier. During investigation of a reproductive problem in a herd grazing coastal pastures in north Queensland, blood serum inorganic phosphorus (P) was measured to determine if deficiency of this element was affecting fertility. Bulls are run continuously with the 700 breeding cows. During October 1974 seventy-four cows were sampled at random from the herd. Plucked pasture samples collected at this time contained 0.085% phosphorus and 1.0% nitrogen. The cows were examined also for pregnancy and lactation status; the serum P (mg/100 ml) for each class is shown in the table. .Although animals which had not produced a calf had the highest serum P values, there was no significant change with age in serum P, which was' 4.22, 3.82 and 3.99 mg/100 ml respectively-for cows 2 years old, 3-6 years old and over 6 years. Pregnant cows showed slightly but not significantly lower blood P levels than the non pregnant cows, while lactation significantly (PCO.05) depressed blood P values. In a recent review on phosphorus and the grazing ruminant, Cohen (1975) has drawn attention to the danger of extrapolating from overseas results to the Australian situation and points out that there is no conelusive evidence that phosphorus per se plays any special role in reproduction or milk production in the beeFcow. Most reported responses in milk yield and,fertility have been confounded byincreased intakes of energy and protein. The cattle observed in our study appeared to be able to maintain reasonable levels of blood P despite low levels of phosphorus in the available pasture. Serum P levels were more a reflection of past reproductive performance than a cause of fertility response. Supplementation with phosphorus was not recommended. REFERENCES Cohen, R.D.H. (1975) Australian Meat Research Committee Reviews. 23:l. - *Department of Tropical Veterinary Science, James Cook University, Townsville, Q. 48Il. 4P