| Summary: | 碩士 === 東海大學 === 畜產與生物科技學系 === 104 === Our experiment was made up of two parts. The first part was to investigate the effect of supplementing monensin on physiological changes and energy balance after calving in transition Hostein dairy cows.
20 multiparous Holstein cows used in a random block design were either fed without supplementation (control, CO), or supplemented with monensin (treatment, 350 mg/herd/day, MO). Beginning at 21 days before the expected calving date through 63 days postpartum, blood samples were collected every week and milking profile、milk production and rumen VFA were measured twice a week. Blood urea nitrogen (BUN) and triglyceride (TG) concentrations were significantly increased (P<0.05) with the use of monensin. However glucose and aspartate aminotransferase (AST) concen-trations were not affected by monensin supplementation. Milk production、milk fat percentage、milk protein percentage and somatic cell count were similar (P> 0.05) for MO and CO. On the other hand, milk SNF tended to be higher for MO (P=0.05) than CO, and milk lactose was significantly higher (P<0.05) for MO. Rumen pH value、molar VFA concentration and total VFA concentration were not changed (P>0.05), but the acetate: propionate ratio in rumen was significantly increased in MO (P<0.05).
The second part of this experiment was to investigate the effect of monensin supplementation on growth and reproduction in Holstein heifer. 20 Holstein heifers aged 7.5 month were randomly assigned to either the group without supplementation (control, CO), or group supplemented with monensin (treatment, 200 mg/herd/day, MO). The experiment lasted -16 weeks. TG significantly increased (P<0.05) and BUN tended to be higher in MO (P=0.08) but AST concentration significantly decreased (P<0.05). Adding monensin significantly increased average daily gain (ADG) (P<0.05) but body height、 length and gird did not change (P>0.05). Age at puberty of MO was significantly lower (P<0.05) than CO.
The supplementation of monensin contributed to changes in rumen environment and increased the metabolism of fat and protein. It also miti-gated negative energy balance in Holstein cows during the transition period. In Holstein heifer, the effect of monensin supplementation increased growth performance and reproductive efficiency.
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