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Assessing phosphorus overfeeding in dairy cows

Nordqvist, Maria (2012). Assessing phosphorus overfeeding in dairy cows. Uppsala : Sveriges lantbruksuniv. , Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård, 0347-9838 ; 279
ISBN 978-91-576-9081-4
[Licentiate thesis]

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Faecal total phosphorus (TP) from dairy cows consists of a largely insoluble fraction and a soluble P fraction (SP), which mainly represents excess P. The soluble fraction increases proportionately with increased P feeding as excess P is mainly excreted with the faeces in soluble form. Determination of the acid-soluble P fraction in faeces has been suggested as a useful tool to identify excessive P feeding.
The overall aim of this licentiate thesis was to gain a better understanding of how different fractions of faecal samples can be used as tools to map P (over)feeding in dairy cows.
Paper I studied faecal excretion of different P fractions in 42 dairy cows fed a wide range of rations with varying P content ranging from approximately 70% up to 190% of their requirement. Faecal excretion of TP and SP was determined. The slope of the regression indicated that there was a significant relationship between actual measured SP and indirectly calculated regulated P. TP and SP were correlated and it was suggested that they can both serve as markers of P overfeeding
Paper II screened intake and faecal excretion of P on Swedish commercial dairy farms, with special emphasis on comparing farms with organic (N=14) and conventional (N=15) production systems. In each herd, intake of P and other nutrients in feeds was determined for 10 cows in varying stages of lactation. Milk yield and faecal content of P (TP and SP) were also determined for these cows. The results indicated that cows in both management systems consumed more P than they required. However the level of overfeeding was higher for cows in conventional systems. Pooling faecal samples from lactating cows improved the correlation between faecal P concentration and calculated P requirements. SP and TP appeared to be equally good in reflecting P intake relative to predicted requirement. It was shown that slurry samples could be used to evaluate P feeding on herd level.
In conclusion, this thesis showed that P overfeeding is greater in conventional dairy herds than in organic dairy herds and that both SP and TP in faecal samples can be used as markers of P overfeeding in dairy cows.

Authors/Creators:Nordqvist, Maria
Title:Assessing phosphorus overfeeding in dairy cows
Series Name/Journal:Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård
Year of publishing :21 May 2012
Number of Pages:39
I.Nordqvist, M., Spörndly, R., and Holtenius, K. Fecal phosphorus excretion in lactating dairy cows. Submitted.
II.Nordqvist, M., Holtenius, K., and Spörndly, R. Methods for assessing phosphorus overfeeding on organic and conventional dairy farms. Submitted.
Place of Publication:Uppsala
Publisher:Dept. of Animal Nutrition and Management, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-9081-4
Publication Type:Licentiate thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L02 Animal feeding
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Agrovoc terms:dairy cows, phosphorus, animal feeding, overfeeding, sweden
Keywords:dairy cow, phosphorus, faeces
Permanent URL:
ID Code:8898
Department:(VH) > Dept. of Animal Nutrition and Management
External funders:Stiftelsen Lantbruksforskning
Deposited By: Maria Nordqvist
Deposited On:25 May 2012 12:49
Metadata Last Modified:02 Dec 2014 10:51

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