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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #111031
Title: RELATIONSHIP BETWEEN ESOPHAGEAL DIET SAMPLES, CLIPPED FORAGE SAMPLES, AND WEIGHT GAIN OF STEERS

Author
item Blummel, Michael
item Grings, Elaine

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2000
Publication Date: 6/1/2000
Citation: BLUMMEL, M.R., GRINGS, E.E. RELATIONSHIP BETWEEN ESOPHAGEAL DIET SAMPLES, CLIPPED FORAGE SAMPLES, AND WEIGHT GAIN OF STEERS. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT. 2000. v. 78(Suppl. 1). v. 102.

Interpretive Summary: The relationship between pasture quality and weight gain (WG) of steers was examined monthly from May to September in 1993 and 1994. Pasture quality was assessed by esophageal diet (EDS) and by clipped forage sampling (CFS). EDS and CFS were analysed for chemical parameters and 48 h in vitro organic matter digestibility (IVOMD); additionally kinetics of fermentation were estimated by an in vitro gas production (GP) test. Kinetics of GP were described by exponential and by sigmoidal models. To assess the impact of rumen nitrogen (N) recycling on forage utilization CFS were incubated in N-low and N-rich medium. Monthly WG of steers from May to September were 1.50, 0.92, 0.84, 0.85 and 1.42, 0.91, 0.47 and 0.85 kg/day in 1993 and 1994, respectively. Chemical parameters and IVOMD of EDS were more closely related to WG than the respective parameters of CFS (P<0.01 vs P<0.05). No model of in vitro GP fit all periods. Exponential models fit better (P<0.05) than sigmoidal in early season while the reverse was true for later season. In vitro GP from EDS was positively related to WG (R**2=0.79; P<0.01) while this relationship was only insignificantly positive for CFS incubated in N-low medium. Supplementation with N improved this relationship and up to 70% (P<0.01) of the variation in gain was thus accounted for. The reason for this improvement is seen in underestimation of available N in CFS. Best correlations with WG were obtained by a combination of IVOMD and GP values of EDS and up to 87% (P<0.001) of the variation in WG were thus accounted for. In this model the regression coefficients were positive for IVOMD but negative for GP.

Technical Abstract: The relationship between pasture quality and weight gain (WG) of steers was examined monthly from May to September in 1993 and 1994. Pasture quality was assessed by esophageal diet (EDS) and by clipped forage sampling (CFS). EDS and CFS were analysed for chemical parameters and 48 h in vitro organic matter digestibility (IVOMD); additionally kinetics of fermentation were estimated by an in vitro gas production (GP) test. Kinetics of GP were described by exponential and by sigmoidal models. To assess the impact of rumen nitrogen (N) recycling on forage utilization CFS were incubated in N-low and N-rich medium. Monthly WG of steers from May to September were 1.50, 0.92, 0.84, 0.85 and 1.42, 0.91, 0.47 and 0.85 kg/day in 1993 and 1994, respectively. Chemical parameters and IVOMD of EDS were more closely related to WG than the respective parameters of CFS (P<0.01 vs P<0.05). No model of in vitro GP fit all periods. Exponential models fit better (P<0.05) than sigmoidal in early season while the reverse was true for later season. In vitro GP from EDS was positively related to WG (R**2=0.79; P<0.01) while this relationship was only insignificantly positive for CFS incubated in N-low medium. Supplementation with N improved this relationship and up to 70% (P<0.01) of the variation in gain was thus accounted for. The reason for this improvement is seen in underestimation of available N in CFS. Best correlations with WG were obtained by a combination of IVOMD and GP values of EDS and up to 87% (P<0.001) of the variation in WG were thus accounted for. In this model the regression coefficients were positive for IVOMD but negative for GP.