Abstract:
Proc. Aust. Soc. Anim. Prod. 1996 Vol. 21 EFFECTS OF PHOSPHORUS ON PERFORMANCE OF GRAZING COWS AND CALVES C.P. MILLERA, L.A. FITZPATRICKB, S.J. WHITEC D.B. COATESD and J.H. TERNOUTH * Dept of Primary Industries, Mareeba, Qld 4880 * Biomedical and Tropical Veterinary Sciences, James Cook University, Townsville, Qld 48 11 'Dept of Agriculture, The University of Queensland, Brisbane, Qld 4072 D CSIRO Division of Tropical Crops and Pastures, Davies Laboratory, Townsville, Qld 48 14 C The effects of soil and forage phosphorus (P) in combination with nitrogen (N) and P supplementation were studied in pregnant and lactating cows. The project seeks also to define dietary P requirements (Coates et al. 1996) and to develop diagnostic tests of P deficiency (White et al. 1996). Groups of 8-10 young, Brahman-cross cows grazed in paddocks of very low (2 ppm Colwell), low (4 ppm) and medium (7-10 ppm) levels of soil P. Pastures were native grass, partly oversown with Seca and Verano stylo. Supplements (Table 1) were fed year-round as calcium phosphate (10 g P/cow.day) and urea (23 g Nkead.day). Cows, pregnant with their first or second calf, were introduced in June 1993 and June 1994. Cows calved in October-November and calves were weaned in late March. Ovarian activity of cows was checked every 2-4 weeks between January and June by a combination of ultrasound ovary examination and progesterone analysis of plasma. Daily milk production was measured in mid-lactation by a weigh, suckle, weigh technique. Table 1. Cow and calf performance in response to soil P and supplementation, averaged over 2 years The Meat Research Corporation supported this work. COATES, D-B., TERNOUTH, J-H., MILLER, C.P. and WHITE, S.J. (1996). Proc. Aust. Sot. Anim. Prod. WHITE, S.J., MILLER, C.P. and TERNOUTH, J.H. (1996). Proc. Aust. Sot. Anim. Prod. 21: 439. 21: 380. 355