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چکیده
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The delivery method of [continuous (CONT) vs. every other day or intermittent (INT)] a glucogenic precursor (GP) which was contained glycerin (500 g/kg), mono-propylene glycol (250 g/kg), calcium propionate (150 g/kg), niacin (1 g/kg) and sulfate-Co (350 mg/kg) on performance, selected blood metabolites and liver enzymes were evaluated. Twenty-four multiparous Holstein fresh cows were allocated in a completely randomized design (8 animals/each treatment) fed individually for a period of 14 days after calving. The experimental groups were: 1) no GP supplementation (CTR), 2) GP offered as an oral drench once a day (GP-CONT) on days 3, 4, 5, 6, and 7 after calving and 3) GP offered as an oral drench once a day intermittently (GP-INT) on days 3, 5, 7, 9, and 11 after calving. The amount of oral drenched GP was 1 kg/d. Blood was obtained on 5 and 14 days in milk. Dry matter intake (DMI) was increased (P = 0.05) in GP-INT cows compared to GP-CONT but not control cows. The yield of fat corrected milk was greater in CTR cows than in GP supplemented cows (P = 0.01). The milk protein and fat content were greater for GP-CONT and CTR groups, respectively. Milk somatic cell count was decreased in GP supplemented cows than in CTR cows (64.5 vs. 365 ×103/ml; P = 0.02). Plasma total protein concentration was greater in GP-CONT group. Insulin concentration was increased for GP-CON animals on day 5 (P < 0.05). Nonesterified fatty acids and β-hydroxybutyrate as well as liver enzymes were unaltered by treatments. However insulin sensitivity index was lower in supplemented treatments with GP rather than control group (P < 0.05). In conclusion, the intermittent delivery of glucogenic precursor may be recommendable in fresh cows based on DMI criteria, which warrants further studies.
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