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Phosphorus to horses and cows

Ögren, Gunilla (2013). Phosphorus to horses and cows. Uppsala : Sveriges lantbruksuniv. , Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård, 0347-9838 ; 283
ISBN 978-91-576-9116-3
[Licentiate thesis]

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Abstract

It is important from a nutritional perspective to meet the phosphorus (P) requirements of animals. From an environmental perspective however, it is important not to feed more P than necessary, because excessive P will mainly be excreted with feces, and the soluble P fraction is vulnerable to runoff losses and may contribute to eutrophication. The recommended dietary P levels to dairy cows have successively decreased over the years but recently, an increase in the requirements to growing horses was suggested because fecal endogenous P losses might be higher than previously estimated. The main aim of this thesis was to assess fecal P losses in growing horses, and in brood mares and dairy cows kept on pasture in Sweden.

In paper I, P balance and fecal P losses in growing horses in training fed a forage-only diet ad lib with (HP) or without (LP) P supplementation was studied. In addition, the proportion of the extractable (in dilute HCl solution) inorganic P fraction (Pi) of total P (TP) in feces was assessed. Fourteen Standardbred horses (aged 20 months) were used in a cross-over experiment. Feed intake was measured and spot samples of urine and feces were collected. Acid insoluble ash was used as indigestible marker to assess daily fecal output. Estimated P retention was low (<1.7 g/day) and only that for diet HP was significantly higher than 0 g/d. The fecal endogenous P losses were estimated to be less than 10 mg/kg body weight, which do not support the suggested increase in P requirements. The proportion of Pi of TP was > 85% and Pi increased linearly with P intake.

In paper II, TP and Pi in feces from lactating and non-lactating dairy cows (n=167) and brood mares (n=74) kept on pasture was investigated and also the use of P supplements. Samples of feces, forages and pastures biomass were collected. The proportion of Pi of TP was greater for lactating horses than lactating cows (63±4 vs 49±5 %). Supplementation of lactating animals with P generally matched their estimated requirements and was therefore justified, while supplementation of non-lactating animals could not be justified.

In conclusion, an increase in P requirement to growing horses seems not to be justified, and the high proportion of Pi in feces from horses indicates that P overfeeding of horses might be potentially more harmful to the environment than P overfeeding of dairy cows.

Authors/Creators:Ögren, Gunilla
Title:Phosphorus to horses and cows
Series/Journal:Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård (0347-9838)
Year of publishing :2013
Volume:283
Number of Pages:43
Papers/manuscripts:
NumberReferences
I.Phosphorus balance and fecal losses in growing Standardbred horses in training fed forage-only diets J ANIM SCI jas.2012-6048; published ahead of print March 11, 2013, doi:10.2527/jas.2012-6048
II.Comparison of fecal phosphorus excretion in grazing horses and cows (manuscript)
Place of Publication:Uppsala
Publisher:Institutionen för husdjurens utfodring och vård, Sveriges lantbruksuniversitet
Associated Programs and Other Stakeholders:SLU - Research Areas for the Future > Future Animal Health and Welfare
ISBN for printed version:978-91-576-9116-3
ISSN:0347-9838
Language:English
Publication Type:Licentiate thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L02 Animal feeding
L Animal production > L51 Animal physiology - Nutrition
Q Food science > Q55 Feed additives
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Agrovoc terms:horses, dairy cows, animal nutrition, phosphorus, supplements, faeces, pasture feeding, unrestricted feeding, environmental impact
Keywords:fosfor, träckprov, nutrition, hästar, kor
URN:NBN:urn:nbn:se:slu:epsilon-e-1440
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-1440
ID Code:10394
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Animal Nutrition and Management
External funders:Stiftelsen Lantbruksforskning
Deposited By: Gunilla K Ögren
Deposited On:08 May 2013 06:03
Metadata Last Modified:15 Apr 2015 22:10

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