EFFECT OF GENOTYPE ON THE MORPHOLOGICAL-CHARACTERISTICS, CHEMICAL-COMPOSITION AND FEEDING VALUE OF 9 BARLEY STRAWS, AND RESPONSES TO SOYBEAN-MEAL SUPPLEMENTATION
F. Herbert et al., EFFECT OF GENOTYPE ON THE MORPHOLOGICAL-CHARACTERISTICS, CHEMICAL-COMPOSITION AND FEEDING VALUE OF 9 BARLEY STRAWS, AND RESPONSES TO SOYBEAN-MEAL SUPPLEMENTATION, Animal Production, 58, 1994, pp. 117-126
Three experiments were conducted to investigate the effect of genotype
on the morphological characteristics, chemical composition and feedin
g value of nine chopped barley straws, and responses of the feeding va
lue to a supplement of soya-bean meal (SBM). In experiment 1, the stra
ws were offered ad libitum to 12 wethers and measurements were made of
straw intake and dry (DMD) and organic (OMD) matter digestibility usi
ng a balanced lattice design with three periods. Experiment 2 used the
same experimental design but the straws were offered ad libitum with
200 g SBM. Experiment 3 measured the dry matter losses (DML) of ground
straws from nylon bags placed in the rumen of three wethers. The exte
nt (b) and rate (c) of DML were estimated using the equation DML = a b(1 - e(-ct)). There were significant differences in the stem height
(P < 0.001), leaf proportion (P < 0.001), and protein (P < 0.001) and
modified acid detergent fibre (P < 0.01) concentrations between the st
raws. Significant (P < 0.05) effects of genotype on intake were seen b
ut the variation in intake between them decreased when the protein sup
plement was added. Effects of genotype on DMD (P < 0.05) and OMD (P <
0.05) were seen in unsupplemented straws and differences of OMD (P < 0
.05) were still apparent when SBM was given with straw. Although there
were significant (P < 0.05) differences in DML after 48 h incubation,
the constants b and c were similar (P > 0.05) across the genotypes. P
rotein concentration in the straw, although closely correlated with in
take, appears to have less value as a predictor of feeding value than
previously thought.