title: Effect of enhancing curd formation during the first colostrum feed on absorption of gamma glutamyl transferase by newborn calves.
abstract: OBJECTIVE
  To examine the effects of curd formation within the abomasum, on the absorption of gamma glutamyl transferase (GGT) from colostrum in newborn calves.
  
  
  METHODS
  An in vivo physiological study with controls, and in vitro examination of calf abomasal fluid.
  
  
  METHODS
  Newborn calves were taken from cows without allowing them to suckle. They were fed either 1.5 kg colostrum or 1.5 kg colostrum plus rennet, with intervals between calving and colostrum feeding ranging from 0.4 to 12.7 h. Absorption of proteins from the whey component of colostrum was assessed from the rise in activity of serum GGT. In in vitro studies, colostrum was incubated with bovine amniotic fluid, newborn calf abomasal fluid or newborn calf forestomach contents, with or without rennet, to test the curd inhibiting effects of components in the abomasal fluid of newborn calves.
  
  
  RESULTS
  In vivo: addition of rennet to the colostrum feed reduced the proportion of calves with serum GGT activity below 500 U/L by 60%. In vitro: 43% of newborn calves lacked curd forming activity in their abomasal fluid, and that deficiency was corrected by adding rennet to the incubation medium.
  
  
  CONCLUSIONS
  Some calves are born with low amounts of curd forming enzyme activity in the abomasum. This may compromise their ability to absorb large whey proteins from the first feed of colostrum. Adding rennet to the first colostrum feed may improve passive immunity in those calves.
authors.affiliation: SARDI, Flaxley Agricultural Centre, Strathalbyn Road, PO Box 1571, Flaxley, South Australia 5153.
authors.forename: N G
authors.initials: NG
authors.lastname: Gregory
mesh_terms: D000018:Abomasum / Q000201:enzymology / Q000378:metabolism; D000042:Absorption; D000821:Animal Feed; D000818:Animals; D000831:Animals, Newborn / Q000276:immunology / Q000378:metabolism*; D002417:Cattle / Q000276:immunology / Q000378:metabolism*; D012085:Chymosin / Q000494:pharmacology*; D003126:Colostrum / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D007112:Immunity, Maternally-Acquired; D008297:Male; D005723:gamma-Glutamyltransferase / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: C025350:rennet; D005723:gamma-Glutamyltransferase; D012085:Chymosin