Abstract
Eight ruminally cannulated Holstein bull calves were used in a switchback design to evaluate effects of hay on post-prandial changes in ruminal pH, ammonia and VFA, blood ketones, and plasma glucose, NEFA, VFA, and urea N. Calves were fed 4.5 kg/d of calf starter with or without hay for ad libitum consumption. Blood and ruminal fluid were sampled every 2h for 12h on d 21 (periods 1 and 2) or d 13 (period 3). Ruminal pH declined from 6.6 at 0h to 5.3 by 2h. Changes in ruminal and plasma VFA were consistent with low pH and rapid fermentation of soluble carbohydrate. Ruminal ammonia, molar percentage butyrate, and blood ketones, plasma urea N, and plasma molar percentage butyrate were lower when hay was fed. Postprandial increases in blood β-hydroxybutyrate and acetoacetate were reduced when hay was fed, and correlated .65 and .50, respectively, to ruminal butyrate. Concentration of β-hydroxybutyrate averaged 1.24 and 1.87 mmol/L at 4h postfeeding. These data suggest that rapid consumption of limited amounts of grain increased in ruminal VFA and blood ketones; increase in ketones was smaller when hay was included in the diet.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
