|Hall, Mary Beth|
Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2010
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: The objective of this study was to evaluate the impact of post-ruminal starch digestion on inflammatory response in dairy cattle. Six cull, nonpregnant, nonlactating, multiparous cannulated Holstein dairy cows (BW 804±101 kg) were fed a high forage diet ad libitum starting 15 d before the infusion period. Cows were infused abomasally 12 h per day for 3 days with approximately 8 L d-1 of 0.9% saline solution (CTRL; 2 cows) or a 0.9% saline suspension of 4 kg of corn starch with 4 g xanthan gum (ST; 4 cows) using peristaltic pumps. Fecal samples, blood samples, and other measures were taken every 4 h (offset daily by 1 h). Data were analyzed as repeated measures with cow within treatment as a random variable. Fecal pH data showed 2 distinct responses to ST (ST1 and ST2). Fecal pH of all cows averaged 6.90 before infusion. During infusion days, fecal pH remained at 7.0±0.25 for CTRL, but declined in ST cows to 5.1 (ST1) and 4.9 (ST2) by the end of day 2, and diverged to 5.3 (ST1) and 4.6 (ST2) by the end of day 3. The increase in fecal pH for ST1 cows during day 3 suggests an increase in small intestinal digestion of starch, whereas a continuing decline in fecal pH for ST2 cows suggests that they did not adapt similarly. Fecal pH differed among CTRL, ST1, and ST2 (P<0.01). Blood values for haptoglobin decreased for CTRL and ST1 with day of infusion, but increased for ST2 with day 3 values of 12.3, 7.8, and 24.5 mg dl-1, respectively (P=0.04). Fibrinogen mg dl-1 tended to differ by treatment x infusion day, rising from 109 to 198, 143 to 188, and 221 to 250 between day 1 and 3 of infusion for CTRL, ST1, and ST2, respectively (P=0.11). Neither ceruloplasmin (P=0.38) nor alpha-acid glycoprotein (P=0.46) differed by treatment. Hematocrit tended to be greater for CTRL than ST (32.9 v 29.1%; P=0.08). Rectal temperature showed treatment x day effects with increases from day 1 to 3 of 38.5 to 38.7, 38.4 to 39.0, and 38.9 to 39.1°C for CTRL, ST1, and ST2, respectively (P<0.01); CTRL tended to be less than ST (P=0.09). Respiration rates did not differ (P=0.46). The basis for differing cow responses to post-ruminal starch load requires further evaluation.