Serum amylase activity and calcium and magnesium concentrations in young cattle grazing fescue and Bermuda grass pastures.
The study reported here was part of a long-term investigation of the effects of genotype on growth, reproduction, and metabolism in cattle grazing common Bermuda grass and endophyte-infected fescue pastures. In June 1990, blood samples were collected from the tail vein of yearling heifers and steers (Angus [AA], Brahman [BB], and their reciprocal crosses [AB, BA], n = 97). Serum amylase activity was assayed enzymatically; serum Ca and Mg concentrations were determined by atomic absorption spectrophotometry. The effects of endophyte-infected fescue depended on genotype (P less than 0.001). In yearlings having at least 1 Angus parent (AA, AB, BA), grazing endophyte-infected fescue was associated with higher serum amylase activity than was grazing Bermuda grass. But serum amylase activities of BB yearlings consuming either forage were similar. Moreover, for either forage, substantial differences were related to genotype (P less than 0.007) and gender (P less than 0.05). Angus yearlings had higher serum amylase activity than did Brahman yearlings; AB and BA yearlings had intermediate values. Heifers had higher amylase activity than did steers. The relationship among serum values of amylase, Ca, and Mg depended on forage. Yearlings consuming endophyte-infected fescue and having at least 1 Angus parent had a moderate negative correlation between serum amylase activity and Ca concentration (r = -0.53; P less than 0.0005); that is, in calves of genotypes with increased amylase activity while consuming endophyte-infected fescue (AA, AB, BA), the higher the amylase activity, the lower the serum Ca concentration. However, in yearlings consuming Bermuda grass, serum amylase and Ca values were not correlated.(ABSTRACT TRUNCATED AT 250 WORDS)
Nutting
D F
DF
Department of Physiology and Biophysics, College of Medicine, University of Tennessee, Memphis 38163.
Tolley
E A
EA
Toth
L A
LA
Ballard
S D
SD
Brown
M A
MA
D000681:Amylases / Q000097:blood*; D000821:Animal Feed; D000818:Animals; D001947:Breeding; D002118:Calcium / Q000097:blood*; D002417:Cattle / Q000097:blood* / Q000235:genetics; D005260:Female; D005838:Genotype; D008274:Magnesium / Q000097:blood*; D008297:Male; D006109:Poaceae; D012727:Sex Characteristics
D000681:Amylases; D008274:Magnesium; D002118:Calcium