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The effect of high ambient temperature on Ca, P and Mg balance and bone turnover in high‐yielding dairy cows
Author(s) -
KAMIYA Yuko,
KAMIYA Mitsuru,
TANAKA Masahito
Publication year - 2010
Publication title -
animal science journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.606
H-Index - 38
eISSN - 1740-0929
pISSN - 1344-3941
DOI - 10.1111/j.1740-0929.2010.00761.x
Subject(s) - chemistry , endocrinology , medicine , bone resorption , bone remodeling , parathyroid hormone , osteocalcin , zoology , lactation , calcium , alkaline phosphatase , biology , biochemistry , enzyme , pregnancy , genetics
We investigated the effect of heat stress on Ca, P and Mg balance and bone turnover in lactating cows. In a 2 × 2 crossover design, four multiparous lactating Holstein cows were kept in a chamber and subjected to a constant moderate (18°C) ambient temperature (MT) or high (28°C) ambient temperature (HT). The cows were fed total mixed ration (Ca, 0.7%; P, 0.4%; Mg, 0.2%) ad libitum . The milk yield under HT (35.4 kg/day) tended to be lower ( P < 0.10) than that under MT (43.2 kg/day). The concentrations of milk P ( P < 0.05) and Mg ( P < 0.01) were significantly lower under HT than MT. The Ca, P and Mg intake ( P < 0.10); Ca ( P < 0.10), P, and Mg ( P < 0.05) secretion into milk; and Ca ( P < 0.05), P ( P < 0.01), and Mg ( P < 0.05) absorption in the intestine were lower under HT than MT. The plasma osteocalcin, a marker of bone turnover, was significantly lower ( P < 0.05) under HT than MT. Heat stress did not affect plasma C‐telopeptide of collagen type I, a bone resorption marker, and plasma parathyroid hormone concentration.