Studies on subacute ruminal acidosis（SARA）in dairy cows

Abstract

The objectives of this study were to reveal the impacts of subacute ruminal acidosis （SARA） and to establish preventive measures against SARA, which has become a problem associated with the management for lactating cows in recent years. In this study, a field survey of SARA, using a wireless radio transmission pH measurement system （pH sensor）, was conducted, and blood levels of various hormones and compounds related to energy metabolism in cows with SARA were evaluated.　Additionally, the preventive effect of wood kraft pulp （KP） was investigated in cows with SARA. First, an epidemiological study using pH sensors revealed that the prevalence of SARA during the 45 days before and after calving ranged from 29.0% to 77.4% in dairy cows kept by dairy farmers in the Mogami region of Yamagata Prefecture. The results suggested that feed type, starch concentration in feed, and feed changes during transition affect the ruminal and reticular pH and SARA incidence in dairy herds.　Second, we monitored ruminal or reticular pH and measured blood concentrations of hormones and metabolites related to energy metabolism in S-farms with high rates of SARA in epidemiological studies. Adiponectin （ADN） concentrations at 4 weeks after parturition correlated with the total amount of time that ruminal or reticulum fluid pH was under the threshold during 1week after parturition. Additionally, there was a strong correlation between the number of days that SARA was detectable based on the criteria in the first 30 days after parturition and ADN concentrations at 4 weeks, and average ADN concentrations at 1 and 4 weeks. There was a negative correlation between mole fraction of acetic acid in rumen and ADN concentrations at 4 weeks post-parturition.　These results suggest that blood adiponectin levels may be useful as an indicator to evaluate SARA, which reflects ruminal pH and condition. Finally, feeding kraft pulp, which has high nutritional value, high fiber content, and slow digestion rate, improved ruminal and reticular pH in dairy cows during the transition period in S farms, although the effects of KP may depend on the constituent concentrations of feeds. In conclusion, this study provides an understanding of SARA, clarifies that ruminal fermentation is related to blood levels of ADN, which is an adipocytokine involved in the regulation of glucose and fatty acid metabolism, and shows the possibility of reducing SARA by feeding kraft pulp.