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Phosphorus Management of Beef Cattle in Northern Australia

Jackson, D., Rolfe, J. W., English, B. H., Holmes, B., Matthews, R., Dixon, R. M., Smith, P. and MacDonald, N. (2012) Phosphorus Management of Beef Cattle in Northern Australia. Project Report. Meat & Livestock Australia.

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Key messages for managing phosphorus nutrition
In many of regions of northern Australia, phosphorus (P) is a serious nutritional limitation to cattle production, reducing its efficiency and profitability.
Some general principles can be applied to strategies and practices when feeding phosphorus to beef cattle.
• The animals that need phosphorus most are growing stock, late-pregnant heifers and cows, and lactating cows.
• Deficient animals respond best to P supplement when their diet has adequate protein and energy. This is why P supplementation is most effective during the wet season.
• Signs of acute phosphorus deficiency include bone chewing, broken bones, peg-leg, poor body condition of breeders and botulism.
• There are no simple diagnostic tests for the P status of cattle. Blood and faecal P are the most useful indicators.
• If P is fed over the wet season on deficient country:
– young growing stock can increase their growth by 30–40kg/year
– breeders can increase weaning rates by 10–30%
• Deficiency is related to soil P status. As a general rule, where soil P levels:
– are deficient (5mg/kg or less), all classes of stock are likely to respond to feeding P
– are marginal (6–8mg/kg), young breeders are likely to respond to feeding P
– exceed 8mg/kg, the economic benefit from feeding mature cows diminishes.
• Responses to P supplement may be lower if animals running on P-deficient country have access to adjacent areas of high-P soils, such as frontage country.
• Supplements should be compared on the cost of their P content, on the practicality of feeding out and on whether the animals will be able or willing to eat target amounts.
• A typical wet season loose-mix P supplement should contain at least 8% P; a typical dry season supplement will contain 2–4% P and also non-protein nitrogen (eg urea).
• On deficient country, lowering the stocking rate will not reduce the need to feed phosphorus.
• Where the native pasture on deficient country contains sufficient stylo, cattle may respond significantly to P supplement during the dry season because of the extra
protein in their diet.
• Because cattle eat more pasture when P supplements are fed, stocking rates should be reduced to avoid overgrazing.
• The economic benefits from feeding P are maximised when done in conjunction with other aspects of good herd management.

Item Type:Monograph (Project Report)
Business groups:Animal Science
Keywords:Final Report
Subjects:Agriculture > Agriculture (General) > Farm economics. Farm management. Agricultural mathematics
Agriculture > Agriculture (General) > Agriculture and the environment
Animal culture > Cattle
Animal culture > Feeds and feeding. Animal nutrition
Live Archive:26 May 2022 03:58
Last Modified:26 May 2022 03:58

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