Validation and demonstration of a diagnostic tool for phosphorus status of beef cattle
The Validation and demonstration of a diagnostic tool for phosphorus status of beef cattle project sought to validate the ratio of faecal phosphorus (P) to diet digestibility (DMD) as a diagnostic tool for P deficiency in beef cattle and demonstrate production responses at different P intakes. It also investigated the carryover effect of using P supplements in the dry season for subsequent wet season responses, in the absence of P supplements.
Much of northern Australia is based on soils that are deficient in phosphorus (P), an essential nutrient for growing and breeder cattle. A robust test is required by industry to determine the P content of diets grazed by cattle.
This project aimed to validate the use of the ratio of the concentration of P in the faeces (FecP) to the metabolisable energy (ME) content (FecP:ME; mg P/MJ ME) of the diet as a diagnostic test for the adequacy of dietary P content in relation to energy intake and to determine the likely response of cattle to P supplementation. Feed intake, liveweight gain, the concentration of P in plasma (PiP), FecP and FecP:ME increased with increasing diet P content and P intake. Plasma inorganic P was the best indicator of P intake of steers consuming a high N, high ME diet and under grazing conditions.
The responses of FecP:ME and FecP:dietary N content to increasing diet P were similar when dietary ME and N content were constant. In a field experiment auto-drafters were used to draft cattle to allocated P supplement treatments in a single paddock. Under these extensive grazing conditions the FecP:ME indicated that indicator steers and breeders were P deficient but no response to P supplementation was evident and serum inorganic P concentration suggested that the indicator steers were not P deficient.
The FecP:ME may require further validation across a range of land types/pasture bases before it can be recommended for wide use by industry.
When: 1 May 2010 to 15 December 2013
Contact: Simon Quigley and Tim Schatz
For more details, please read the final report summary and download the final report (B.NBP.0537) (PDF, 3.9 MB) from the Meat & Livestock Australia website.