Short communication: analysis of immune function in lactating dairy cows fed diets varying in phosphorus content.
The aim of this study was to evaluate the effect of varying dietary P on bovine immune function. Nine first- or second-lactation Holstein cows were fed diets varying in P in a 3 x 3 Latin square design. Diets were formulated to contain either low (0.34%, no supplementary P), medium (0.43%), or high (0.52%) P. All 3 diets were formulated to meet or exceed current NRC requirements for P content. Between d 21 and 26 of each period, blood samples were collected and serum inorganic P concentration, lymphocyte proliferation, and neutrophil bactericidal activity were measured. Serum P increased with increasing dietary P intake and was greatest in the first lactation compared with subsequent lactations. There was a stage of lactation-dependent increase in lymphocyte proliferation after stimulation with concanavalin A, phytohemagglutinin, or pokeweed mitogen. However, dietary P did not alter lymphocyte proliferation or neutrophil bactericidal activity in vitro. In conclusion, decreasing dietary P to reduce manure P content and the risk of P losses from farms to surface water does not have an adverse effect on the innate or cell-mediated immune responses of lactating dairy cattle.
Mullarky
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Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA. mullarky@vt.edu
Wark
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Dickenson
M
M
Martin
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Petersson-Wolfe
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CS
Knowlton
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KF
D000818:Animals; D002417:Cattle / Q000276:immunology / Q000502:physiology*; D003612:Dairying; D004032:Diet / Q000662:veterinary*; D005260:Female; D007111:Immunity, Cellular / Q000502:physiology*; D007113:Immunity, Innate / Q000502:physiology*; D007774:Lactation / Q000502:physiology*; D010758:Phosphorus / Q000502:physiology*
D010758:Phosphorus