Ruminal fermentative parameters and blood acido-basic balance changes during the onset and recovery of induced latent acidosis in sheep

• Main Authors: Brossard, Ludovic, Martin, Cécile, MICHALET-DOREAU, Brigitte
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: rumen fermentation; acidosis; protozoa; blood; acid-base status > - acidose; fermentation ruminale; protozoaires; sang; équilibre acido-basique; [SDV.SA.ZOO]Life Sciences [q-bio]/Agricultural sciences/Zootechny; Carbonic acid
• Online Access: https://hal.archives-ouvertes.fr/hal-00889989; https://hal.archives-ouvertes.fr/hal-00889989/document; https://hal.archives-ouvertes.fr/hal-00889989/file/hal-00889989.pdf; https://doi.org/10.1051/animres:2003036

International audience Four ruminal cannulated Texel wethers were used to study the long-term effects of an acidotic diet on ruminal parameters and blood acid-base status. The short-term events around feeding and the recovery of the animals were followed after this nutritional disturbance. Sheep were limit-fed consecutively a control diet H (100% hay) (one week), an acidotic diet W (60% wheat + 40% hay) (2 weeks), and again the control diet (2 weeks). Mean, minimum and maximum ruminal pH were lower, and the time and area under pH 6.0 were higher ($P < 0.001$) with the W diet than with the H diet. These pH parameters indicate a latent acidosis defined here as a subacute and maintained acidosis. Before feeding, the drop in ruminal pH with the W diet was correlated with an increase in the VFA buffering capacity (BC) (R$^2 = 0.70$) and with a decrease in the BC of both carbonic acid functions (R$^2 = 0.52$ for H$_2$CO$_3$ and 0.55 for HCO$_3^-$). After feeding, the acidotic diet effect on ruminal pH was not explained by variations in the BC of either of these chemical species. Ruminal lactate concentration was higher with the W diet compared to the H diet ($P < 0.001$) but remained low ($<$ 2 mmol$\cdot$L$^{-1}$). Total VFA concentration ($P < 0.001$), acetate ($P < 0.001$) and propionate ($P < 0.01$) proportions in the rumen decreased with the W diet, while the butyrate proportion increased ($P < 0.001$). The number of Entodiniomorphs increased with the W diet ($P < 0.001$). Most parameters showed no significant variation between the 2 weeks with the W diet ($P > 0.05$). All ruminal parameters, except for ammonia, recovered to initial levels during the H diet redistribution ($P < 0.05$) while blood parameters decreased (pH, $P < 0.05$; bicarbonates (HCO$_3^-$), total CO$_2$ content (TCO$_2$), base excess in whole blood (Beb) and in extra cellular fluid (Beecf), $P < 0.01$). This decrease, initiated during the distribution of the acidotic diet, suggests a mobilization of body ...