Location: Livestock Issues ResearchTitle: Heat production, respiratory quotient, and methane loss subsequent to LPS challenge in beef heifers
|ALTMAN, ALEXANDER - University Of Kentucky|
|VANZANT, ERIC - University Of Kentucky|
|Carroll, Jeffery - Jeff Carroll|
|MCLEOD, KYLE - University Of Kentucky|
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 1/8/2016
Publication Date: 3/4/2016
Citation: Altman, A.W., Vanzant, E.W., Carroll, J.A., Sanchez, N.C., Mcleod, K.R. 2016. Heat production, respiratory quotient, and methane loss subsequent to LPS challenge in beef heifers. Journal of Animal Science. 94:No. Supplement 1, pg.20.
Technical Abstract: Respiration calorimetry was used to measure energy utilization during an acute phase response (APR) to lipopolysaccharide (LPS). Eight Angus heifers (208 +/- 29.2 kg) were randomly assigned to one of two calorimeters in four 2-day periods for measurement of heat production (HP), methane (CH4), and respiratory quotient (RQ). Corn silage diets were fed at 1.0 X NEm. Exit velocity measured at weaning (wEV) was an indicator of temperament. Rectal temperature (RT) was recorded every five minutes using indwelling temperature loggers. Data from day 1 served as a control (CON) for each heifer. Lipopolysaccharide was administered intravenously at 0.5 micrograms/kg body weight 2 hours after feeding on day 2 (0 hour). Respiratory gas exchange was determined at 10 minute intervals from 0 hour to 24 hours. At each time point, RQ was determined and HP was calculated from O2,, CO2, and CH4 changes using Brouwer’s equation. Data were divided into two 12-hour periods (Phase I and Phase II) for repeated measures analysis with SAS Proc Mixed. After LPS, RT revealed a biphasic response typical of an LPS challenge. For both CON and LPS periods, RQ declined postprandially (0.95-1.00 to 0.85-0.90) across Phase I (time x LPS P<0.01). With LPS, RQ during the first 6 hours of Phase I tended to be more erratic, whereas values during the latter half of this phase were generally lower with than without LPS. A wEV x LPS interaction was detected for RQ during Phase II (P=0.05) in which LPS-induced depression in RQ increased with increasing wEV. The average RQ was 0.86 and 0.80 +/- 0.004 for CON and LPS, respectively, during Phase II. There was large individual animal variability in HP response to LPS in which some animals increased and some decreased HP in response to LPS. Thus, no time x LPS (P>0.10) or LPS (P>0.12) effects were found for HP in either phase. However, wEV effects were found (P<0.04) in both phases, where HP increased by about 7 to 8% of mean HP for each 1m/s increase in wEV. Methane production (L/min) was reduced by 23% with LPS in Phase I. In Phase II, LPS-induced reduction in CH4 was influenced by wEV (P=0.03). At low wEV, LPS effects were nonsignificant (P=0.17), whereas at average and high wEV, CH4 was depressed (P<0.01) by 33 and 54%, respectively. Heat production responses during the APR of LPS challenge were highly variable among individuals, yet HP among individuals was related to weaning exit velocity.