Chromium supplementation and substitution of barley grain with corn: effects on metabolite and hormonal responses in periparturient dairy cows
2012
Sadri, H. | Rahmani, H. R. | Khorvash, M. | Ghorbani, G. R. | Bruckmaier, R. M.
Thirty‐two multiparous Holstein cows were used to investigate the effects of chromium‐l‐methionine (Cr‐Met) supplementation and dietary grain source on metabolic indices throughout the periparturient period. Cows were fed a total mixed ration with the concentrate portion based on ground barley (barley based diet, BBD) – or ground corn (corn‐based diet, CBD) from 21 days before anticipated calving through 28 days after calving. The Cr‐Met was supplemented at dosages of 0 or 0.08 mg of Cr/kg of metabolic body weight throughout the experiment. Thus, treatments were in a 2 (Cr‐Met) × 2 (grain sources) factorial arrangement. Plasma glucose, non‐esterified fatty acids, triglyceride, very low‐density lipoprotein, blood urea nitrogen (BUN), insulin, glucagon, cortisol and insulin‐like growth factor‐I (IGF‐I) concentrations were not affected by chromium supplementation on calving day (d 0). However, there was a trend for decreased β‐hydroxybutyrate (BHBA) and increased cholesterol on d 0 in cows fed the Cr supplemented diet. On d 21 postpartum (wk 3 p.p.), plasma glucagon concentration tended to be greater in cows fed the Cr supplemented diet. However, other plasma metabolite and hormone measures were not affected by Cr supplementation in wk 3 p.p. There was no effect of grain source on d 0 plasma metabolic and endocrine measures. In wk 3 p.p., a significant difference was found only for plasma concentration of glucagon that was higher for cows fed the BBD compared with the CBD. There was an interaction of Cr‐Met supplementation and grain source in wk 3 p.p. plasma concentration of BUN to decrease in CBD and increase in BBD, supplemented with Cr‐Met. No Cr by grain interactions were observed for other plasma metabolic variables on d 0 and in wk 3 p.p. These results indicate that Cr‐Met supplementation and substituting barley grain with corn throughout the transition period have only moderate effects on metabolic and endocrine parameters.
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