title: Milk production, reproductive performance, and fecal excretion of phosphorus by dairy cows fed three amounts of phosphorus.
abstract: Milk production was measured and phosphorus (P) excretion in feces was estimated in dairy cows fed three amounts of P. A basal diet was formulated to contain 0.31% P (DM basis). Sodium monophosphate replaced corn in the basal diet to give two additional diets containing 0.40 and 0.49% P. The diets were fed to eight, nine, and nine multiparous Holsteins from the beginning to the end of lactation. Milk yields for the 308-d lactation were 10,790, 11,226, and 11,134 kg for the three treatments, respectively. The lowest milk yield resulted from decreased milk production during late lactation with the 0.31% P group. Reproductive performance of the cows was not related to dietary P content. Fecal P concentration, determined in wk 2, 4, 6, 8, 23, and 40 of lactation, increased as dietary P intake was increased. Cows fed the lowest P diet conserved P by minimizing P excretion in feces and urine, whereas cows in the other two treatments excreted more P through these routes. A reduction in dietary P from 0.49 to 0.40% reduced fecal P excretion by 23%. Apparent P digestibilities of less than 40% are indicative of surplus dietary P. Feeding 0.40% P appeared sufficient to maintain P balance and the level of milk production achieved in this experiment. An example is given which illustrates the relationship between dietary and fecal P.
authors.affiliation: US Dairy Forage Research Center, USDA-Agricultural Research Service and Dairy Science Department, University of Wisconsin, Madison 53706, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Wu
authors.forename: L D
authors.initials: LD
authors.lastname: Satter
authors.forename: R
authors.initials: R
authors.lastname: Sojo
mesh_terms: D000818:Animals; D001419:Bacteria / Q000378:metabolism; D002118:Calcium / Q000097:blood; D002417:Cattle / Q000502:physiology*; D005243:Feces / Q000737:chemistry*; D005260:Female; D007774:Lactation / Q000502:physiology*; D010758:Phosphorus / Q000097:blood / Q000378:metabolism* / Q000652:urine; D016226:Phosphorus, Dietary / Q000008:administration & dosage*; D011247:Pregnancy; D012098:Reproduction / Q000502:physiology*; D012417:Rumen / Q000382:microbiology; D013997:Time Factors
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus; D002118:Calcium