Effect of sodium monensin on reproductive performance of dairy cattle, 2. Effects on metabolites in plasma, resumption of ovarian cyclicity and oestrus in lactating cows.
1994
Abe N. | Lean I.J. | Rabiee A. | Porter J. | Graham C.
In a randomized trial, cows treated with sodium monensin in a controlled-release capsule had significantly lower plasma Beta-hydroxybutyrate (BHB) concentrations and tended to have significantly higher plasma glucose concentrations than untreated cows. Treatment did not significantly influence plasma free fatty acid, urea nitrogen or cholesterol concentrations. Despite higher plasma glucose concentrations and lower plasma BHB concentrations, periods from calving to first ovulation and oestrus were not reduced by treatment. This observation, with limited number of cows, is not consistent with a hypothesis that glucose or ketones are important metabolic regulators of pulsatic release of luteinising hormone and consequent resumption of cyclicity. While milk production and milk protein concentration did not significantly differ between groups, milk fat concentration was significantly lower for treated cows. Treated cows probably had lower dry matter intake than untreated cows as they produced 67 litres less milk per head and lost more weight than untreated cows during the study period, although weight and body condition score were not significantly affected by treatment. The lack of significance of these latter observations probably reflects the low statistical power of the study.
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