Premium
Estimates of the efficiency of transfer of L ‐histidine from blood to milk when it is the first‐limiting amino acid for secretion of milk protein in the dairy cow
Author(s) -
Kim ChangHyun,
Choung JaiJun,
Chamberlain David G
Publication year - 2001
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.923
Subject(s) - histidine , limiting , latin square , methionine , zoology , meal , tryptophan , chemistry , basal (medicine) , dairy cattle , skimmed milk , food science , amino acid , biology , biochemistry , endocrinology , fermentation , rumen , insulin , mechanical engineering , engineering
The efficiency of transfer of L ‐histidine into milk protein was measured in two experiments in which L ‐histidine was infused intravenously into dairy cows eating a basal diet of grass silage and a cereal‐based supplement containing feather meal. Both experiments used Latin square designs, and infusion periods lasted 10 days. In Experiment 1, histidine was infused alone at doses of 3, 6 and 9 g day −1 . The output of milk protein increased up to the 6 g day −1 dose but fell back to the basal level when 9 g day −1 was infused. The efficiency of transfer was highest for the 6 g day −1 dose, for which the value was 0.38. In Experiment 2 the same three histidine doses as in Experiment 1 were used, but this time the histidine was accompanied by 8 g L ‐methionine, 28 g L ‐lysine and 2.5 g L ‐tryptophan, to ensure that histidine remained first‐limiting over the whole dose range. The output of histidine in milk protein ( Y ) increased linearly with histidine dose ( X ) such that Y = 0.431 X + 0.070 r = 0.998; n = 4, indicating an efficiency of transfer of 0.43. © 2001 Society of Chemical Industry