The impact of highly concentrated Mo and Cu dietary supplements, fed as a bolus, on the efficacy of chelated versus inorganic Cu in cattle on a low-Cu diet

作者：Grace N D; West D M; Smith S L; Knowles S O^*

来源：New Zealand Veterinary Journal, 2013, 61(6): 345-348.

DOI：10.1080/00480169.2012.760398

• Copper
• molybdenum
• thiomolybdate
• dietary supplement
• dairy cow

AIM: To compare the efficacy of chelated versus inorganic forms of dietary Cu supplements, fed as a bolus, when challenged by a daily bolus of dietary Mo in cattle on a low-Cu diet.METHODS: Forty non-lactating, Friesian dairy cows of adequate Cu status were assigned to four groups and fed a basal diet of baled silage containing 5.3mg Cu and 0.4mg Mo/kg DM. The experimental design was a factorial of two chemical forms of supplemental Cu and two levels of Mo intake, provided as pelleted grain supplements made from crushed barley/molasses plus Cu and Mo. The supplements contained 140mg Cu/kg as Cu sulphate pentahydrate (CS), 140mg Cu/kg as Cu glycinate (CG), CS plus 38mg Mo/kg as sodium molybdate (CS+Mo), or CG plus 38mg Mo/kg (CG+Mo). Commencing on Day 0, supplements were fed once daily (offered 1-1.2kg/cow) and were completely consumed within 5-10 minutes, which constitutes a bolus type of administration. Liver samples were collected by biopsy at Days -24, 13, 41 or 47, and 69 for Cu determinations.RESULTS: The diets fed to the Cu+Mo groups were roughly equivalent to 25mg Cu and 5.7mg Mo/kg DM. Mean initial concentration of Cu in liver for all groups was 516 (SE 54)mol Cu/kg fresh tissue. In cows supplemented with CS and CG, the final (Day 69) concentrations increased (p%26lt;0.01) to 939 (SE 166) and 853 (SE 163)mol Cu/kg, respectively. These values were not different (p=0.72). For groups CS+Mo and CG+Mo, the final concentrations of 535 (SE 122) and 453 (SE 102)mol Cu/kg were not different from initial values or from each other (p%26gt;0.25). The rate of accumulation of Cu in liver following bolus Cu and Mo intake was highly variable but was not affected by initial concentration of Cu in liver (p%26gt;0.9) or by the form of Cu (p%26gt;0.6). Mean rates of accumulation of Cu in liver were 4.0 (SD 3.8) and 0.65 (SD 2.0)mol Cu/kg fresh tissue/day for the Cu-only treatments and the Cu+Mo treatments, respectively.CONCLUSIONS: When fed together as a bolus, high Mo intake negated the effect of supplemental Cu but it did not reduce liver Cu stores. There was no difference in the reaction of dietary Mo with chelated Cu (as glycinate) versus inorganic Cu (as sulphate) dietary supplements.

• 出版日期2013-11-1