Relationships among milk urea-nitrogen, dietary parameters, and fecal nitrogen in commercial dairy herds.
Our study objective was to determine the ability of milk urea-nitrogen concentrations ([MUN]) to predict fecal nitrogen concentrations ([Fecal N]) in commercial dairy herds. A total of 83 dairy herds were each visited 3 times within 48 h after a monthly herd milk test. For each farm visit, forages were sampled for nutrient analyses, which were entered into a computerized ration evaluator, and fecal samples were taken per rectum from each of 6 cows (2 early-, 2 mid-, and 2 late-lactation). Fecal samples were pooled, mixed, and analyzed for nitrogen content. Fecal nitrogen concentrations were compared with the routinely measured nutritional parameters from the ration evaluation, and the herd average [MUN] for the previous milk test date using mixed linear regression analyses. Total protein supplied in the ration was significantly positively associated with [Fecal N], but herd average [MUN] was not associated (P > 0.10) with [Fecal N].
Arunvipas
Pipat
P
Department of Large Animals and Wildlife Clinical Science, Faculty of Veterinary Medicine, Kasetsart University, Kamphaengsaen, Thailand.
VanLeeuwen
John A
JA
Dohoo
Ian R
IR
Keefe
Greg P
GP
Burton
Shelley A
SA
Lissemore
Kerry D
KD
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D005243:Feces / Q000737:chemistry*; D005260:Female; D007774:Lactation / Q000378:metabolism; D016014:Linear Models; D008892:Milk / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis*; D014508:Urea / Q000032:analysis*
D004044:Dietary Proteins; D014508:Urea; D009584:Nitrogen