title: Use of age and serum gamma-glutamyltransferase activity to assess passive transfer status in lambs.
abstract: OBJECTIVE
  To develop an algorithm for predicting passive transfer status of lambs of various ages, using the lamb's age and serum gamma-glutamyltransferase (GGT) activity.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  51 Suffolk, Columbia, and crossbred lambs from 1 to 16 days old.
  
  
  METHODS
  Serum was obtained from all lambs. Serum GGT activity was measured, using a commercially available kit. Serum IgG concentration was determined by use of radial immunodiffusion. Day-1 serum IgG concentration was estimated from sample IgG concentration, lamb age, and the published 14-day half-life of IgG in lambs. Stepwise multivariate regression models were developed to estimate day-1 serum IgG concentration as a function of the natural logarithm of serum GGT activity (In[GGT]) and natural logarithm of lamb age (In[age]) at the time of sampling. These regression models were then used to calculate serum GGT activities that were equivalent to various day-1 IgG concentrations in lambs of various ages.
  
  
  RESULTS
  In(GGT) and In(age) were significantly associated with estimated day-1 IgG concentration. Day-1 serum IgG concentration could be predicted using the formula: IgG = -7,686 + 1,366(In[GGT]) + 1,199(In[age]). The model was moderately accurate in predicting serum IgG concentration (R2 = 0.52).
  
  
  CONCLUSIONS
  Serum GGT activity can be used to assess passive transfer status of lambs.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman 99164-7010, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Tessman
authors.forename: J W
authors.initials: JW
authors.lastname: Tyler
authors.forename: S M
authors.initials: SM
authors.lastname: Parish
authors.forename: D L
authors.initials: DL
authors.lastname: Johnson
authors.forename: R G
authors.initials: RG
authors.lastname: Gant
authors.forename: H A
authors.initials: HA
authors.lastname: Grasseschi
mesh_terms: D000375:Aging / Q000276:immunology*; D000465:Algorithms; D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000276:immunology*; D000833:Animals, Suckling / Q000097:blood / Q000276:immunology*; D003126:Colostrum / Q000201:enzymology / Q000276:immunology; D007112:Immunity, Maternally-Acquired; D005779:Immunodiffusion / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood; D011446:Prospective Studies; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D012756:Sheep / Q000097:blood / Q000276:immunology*; D005723:gamma-Glutamyltransferase / Q000097:blood*
chemical_list: D007074:Immunoglobulin G; D005723:gamma-Glutamyltransferase