Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2001
Publication Date: 3/1/2002
Citation: ZIMMERMAN, E.E., STUTH, J.W., NORTHUP, B.K., TOLLESON, D.R. MORPHOLOGICAL AND CHEMICAL CHARACTERISTICS OF SOUTH TEXAS SHRUBS AFFECT INTAKE RATE OF GOATS. JOURNAL OF ANIMAL SCIENCE. 2002. v. 80(Suppl. 2). Abstract. p. 27. Interpretive Summary: Abstract Only.
Technical Abstract: Browse species comprise >30% of the diet in goats (Capra hircus), and their physical and chemical characteristics can affect diet selection. This study determined how leaf, stem and thorn attributes, forage quality, and near infrared reflectance (NIR) characteristics affected bite rate BR (lip and jaw bites) and instantaneous intake (IIR, mg/sec) in Spanish goats. Six xmature nannies were utilized in 5 trials: June, August, October 1994 and January, March 1995. During trials, the goats were isolated and offered individual stems (n=4/goat) from 1 of 8 shrub species for 30 s/stem. Pre- and post-feeding stem weights and numbers of lip and jaw bites were recorded. Measured physical attributes of stems (n=25/species) were: thorn density and length; leaf weight, density and length; undefended leaf length stem length, weight, diameter, and volume. Crude protein (CP) & digestible organic matter (DOM) were determined, and spectra (1108-2492nm) were obtained by NIR spectroscopy. Correlations between plant parameters and intake were calculated, and NIR equations predicting intake were generated by multiple stepwise and modified partial least squares (MPLS) regressions. The only plant characteristic not affecting BR or IIR was CP (P>0.10). The strongest correlations (P < 0.01) were IIR with leaf weight (r=0.65), BR (jaw) with stem diameter (r= -0.75),BR (lip) & thorn lengths (r= 0.60). Strongest correlations among spectralmeasurements and goat responses were BR (lip) with 1612 nm, (r=-0.44), and IIR with 2452 nm (r=-0.51), wave lengths that may be related to anti-nutritive factors. The r2 and SE, for MPLS predictive equations were 0.81/0.02, and 0.75/3.91 (IIR and BR, respectively). Intake of browse species in this study was apparently affected by a combination of physical and chemical factors.