Evaluation of models of acute and subacute acidosis on dry matter intake, ruminal fermentation, blood chemistry, and endocrine profiles of beef steers.

Abstract

Crossbred steers (n = 20; 316 +/- 4 kg BW), each fitted with a ruminal cannula, were used to evaluate the effects of acute acidosis (AA) and subacute acidosis (SA) on DMI, ruminal fermentation, blood chemistry, and endocrine profiles. Animals were blocked by BW and assigned to treatments including 1) intraruminal (via cannula) steam-flaked corn (3% of BW; AA); 2) intraruminal dry-rolled wheat:dry-rolled corn (50:50; 1.5% of BW; SA); 3) offering forage-adapted steers ad libitum access to a 50% concentrate diet (AA control; AC); and 4) offering 50% concentrate diet-adapted steers ad libitum access to a 50% concentrate diet (SA control; SC). Samples of ruminal fluid and whole blood were collected on the day of the challenge (d 0) and 3, 7, 10, and 14 d after the challenge. Daily DMI responded quadratically (P < 0.01) through d 7 for AA and SA steers and increased linearly (P < 0.01) for AC steers. Dry matter intake by AA steers reached a nadir (< 3 kg/d) on d 3 and gradually increased to a level similar to other treatments (7 kg/d) by d 10, whereas DMI by SA steers increased through d 3. Blood pH, bicarbonate, base excess, and total CO2 were decreased (P < 0.03) for AA steers and increased (P < 0.03) for SC steers through d 7. Ruminal pH decreased quadratically (P < 0.01) in AA and AC steers and increased (P = 0.01) in SA steers through d 7. Ruminal total lactate concentration and osmolality responded quadratically (P < 0.01) for AA and AC steers. Ruminal total lactate peaked on d 3 for AA steers and on d 0 for AC and decreased to basal concentrations by d 7. Plasma NEFA concentration increased (P < 0.04) on d 3 and 7 for AA steers. Serum Na decreased (P < 0.05) on d 0 for AA and SA steers and on d 7 and 14 for AA steers. Serum P decreased (P = 0.01) for AA steers through d 7 and decreased quadratically (P = 0.01) for AC steers through d 7. Serum albumin and cholesterol decreased (P < 0.02) for AA and AC steers through d 7. Area under the GH curve decreased (P = 0.02) for AA and AC steers through d 7. Considerable variation was evident in the ability of an animal to cope with a carbohydrate challenge. Results of data modeling generally suggest that serum amylase activity, cholesterol and potassium concentrations, and plasma NEFA concentrations were useful in distinguishing between steers classified as experiencing subacute acidosis or not affected by a carbohydrate challenge.

Effect of intensive fattening of bulls based on a high-grain diet on growth intensity and biochemical and acid-base parameters of blood

“…That is consistent with the results of other authors who recorded increased concentrations of plasma phosphorus in association with experimentally induced acidosis in sheep (Patra et al, 1993;Brown et al, 1999). In contrast, Brown et al (2000) detected decreased levels of serum phosphorus after experimentally induced acidosis in fattened cattle. Average values of plasma magnesium and both transaminases AST and ALT were in the reference range in samples of both collections, and no statistically significant differences between the compared parameters of samples of the two collections were detected.…”

“…Burrin and Britton (1986), who obtained similar results, suggested that a decrease in blood pH and bicarbonate concentrations during the later phase of subacute acidosis indicated depletion of compensatory mechanisms. Less marked changes in bicarbonate and base excess concentrations were recorded during experimentally induced subacute acidosis by intraruminal administration of processed grain (Brown et al, 2000). Harmon et al (1985) found out more marked changes in bicarbonate concentrations after a switch to a diet containing 70% of concentrates, whereas pH decrease was insignificant.…”

“…High doses of grain may seriously influence ruminal fermentation in cattle and cause general health status disturbances (Owens et al, 1998;Sauvant et al, 1999;Galyean and Rivera, 2002). A number of authors investigated changes in acid-base balance and some biochemical parameters of blood plas-ma caused by feeding high-grain diets to fattened cattle (Harmon et al, 1985;Burrin and Britton, 1986;Leedle et al, 1995;Goad et al, 1998;Brown et al, 2000;Hersom et al, 2003;Schoonmaker et al, 2003). Some of the authors recorded decreased concentrations of standard bicarbonate and base excess, accompanied by slightly decreased blood pH in the later phase of subacute acidosis; however, the investigated parameters were in the physiological range (Harmon et al, 1985;Goad et al, 1998;Brown et al 2000).…”

“…A number of authors investigated changes in acid-base balance and some biochemical parameters of blood plas-ma caused by feeding high-grain diets to fattened cattle (Harmon et al, 1985;Burrin and Britton, 1986;Leedle et al, 1995;Goad et al, 1998;Brown et al, 2000;Hersom et al, 2003;Schoonmaker et al, 2003). Some of the authors recorded decreased concentrations of standard bicarbonate and base excess, accompanied by slightly decreased blood pH in the later phase of subacute acidosis; however, the investigated parameters were in the physiological range (Harmon et al, 1985;Goad et al, 1998;Brown et al 2000). Leedle et al (1995) recorded quite a marked reduction in blood pH to 7.3 during the feeding of a highly concentrated diet, whereas Hersom et al (2003) did not find any marked effect of a concentrated diet on acid-base balance in blood.…”

Experimental poisoning by Enterolobium contortisiliquum in sheep

“…These signs was observed when ruminal pH values are near or lower than 5.0. The time frames detected in our study corroborate with findings of several studies on experimentally induced ALRA in cattle, which reported that the onset of signs occurred between 9 and 72h after induction, depending on the protocol adopted (Ortolani 1995, Brown et al 2000, Momcilovic et al 2000, Thoefner et al 2004, Danscher et al 2009, Rodrigues 2009). …”