Relationship between dietary particle size and the incidence of displaced abomasum on Holstein-Friesian dairy farms that feed diets high in maize silage

The aim of this study was to correlate the particle size of total mixed rations (TMR) with the incidence of displaced abomasum (DA) on 13 dairy cattle farms. In each farm, the percentage of lower, middle and upper fraction of TMR was determined by using the Penn State TMR and Forage Particle Separator. Maize silage represents 73% of the TMR. The annual prevalence of DA was 9.1% (105/1150). A positive (r=0.72; n=13; P<0.01) and a negative (r=−0.90; P<0.001) Pearson correlation between the lower or upper TMR fractions and the DA incidence was observed, respectively. The middle TMR fraction was not correlated with the DA incidence in farms. The DA incidence estimation from the TMR fractions was determined by a multiple regression equation: DA (%)=6.92+0.20×lower TMR fraction (%)−1.79×upper TMR fraction (%) (r2 adjusted=0.82; P<0.001). Different percentages of TMR fractions appear to have influenced the DA incidence in these dairy farms. New studies, from a larger population, are necessary to confirm the feasibility of the Penn State Particle Separator usage in order to decrease the annual DA incidence in dairy bovine farms.