Leaf and stem nutritive value of timothy grown with varying N nutrition in spring and summer

Abstract

. Leaf and stem nutritive value of timothy grown with varying N nutrition in spring and summer. Can. J. Plant Sci. 79: 223-229. Nitrogen fertilization is known to have a limited effect on the digestibility of grasses. In a previous paper, however, we reported that N deficiency increased the proportion of leaves in the shoot biomass, and hence, indirectly increased the digestibility of timothy (Phleum pratense L). This was mitigated by the direct negative effect of N deficiency on the digestibility of leaves or stems or both early in the regrowth. The objective of this study was to determine the direct effect of N deficiency on three parameters of nutritive value of leaves and stems of timothy cv. Champ. The evolution of leaf and stem in vitro true digestibility (IVTD), in vitro cell wall digestibility (IVCWD), and neutral detergent fiber (NDF) concentration of field-grown timothy fertilized with four rates of N was studied during a spring and summer regrowth cycle by sampling at weekly intervals. The rate of decline in leaf nutritive value in spring was greater than that in summer, and was less than the rate of decline in stem nutritive value during spring. Nitrogen deficiency consistently increased the NDF concentration of leaves but had a lesser effect on the NDF concentration of stems. Nitrogen deficiency decreased leaf IVCWD when the leaf-to-weight ratio (LWR) was high early in the spring and summer regrowth cycles. At the end of regrowth when LWR values were low, leaf IVCWD was greatest when no N was applied. As a result, the negative effect of N deficiency on the leaf IVTD during the early part of the spring and summer regrowth cycles diminished as the regrowth cycles progressed. Nitrogen deficiency had a limited effect on stem IVCWD. We concluded that the direct negative effect of N deficiency on the digestibility of the timothy shoot biomass can be attributed primarily to its effect on the NDF concentration and cell wall digestibility of leaves. La fertilisation azotée est connue pour avoir peu d'effet sur la digestibilité des graminées. Dans un article récent, nous avons démontré que la déficience azotée augmentait la proportion de feuilles dans la biomasse aérienne, et indirectement, augmentait la digestibilité de la fléole des prés (Phleum pretense L.). Cet effet, toutefois, était contrebalancé par un effet négatif direct de la déficience azotée sur la digestibilité des feuilles, des tiges ou les deux en début de repousse. L'objectif de cette étude était de déterminer l'effet direct de la déficience azotée sur trois paramètres de valeur nutritive des feuilles et des tiges de la fléole des prés cv. Champ. L'évolution de la digestibilité in vitro (IVTD), de la digestibilité des parois cellulaires (IVCWD), et de la teneur en parois cellulaires (NDF) des feuilles et des tiges de fléole des prés cultivée au champ sous quatre niveaux d'azote a été étudiée sur des repousses de printemps et d'été utilisant des prélèvements hebdomadaires. La vitesse de diminution de la valeur nutritive des feuilles au printemp...

Yield and Composition of Sweet Pearl Millet as Affected by Row Spacing and Seeding Rate

“…The ADF (403–437 vs. 342–367 g kg −1 DM) and NDF (656–677 vs. 610–614 g kg −1 DM) concentrations were greater in stems than in leaves but the leaves had a greater dNDF (695–716 vs. 487–540 g kg −1 NDF) than the stems. Differences in nutritive value attributes between leaves and stems have been reported in several species (Bélanger and McQueen, 1999) but this is the first report on sweet pearl millet. Our results suggest that stems of sweet pearl millet could be used primarily for the extraction of sugars while the primary use of leaves could be for feeding cattle.…”

Biomass Partitioning, Forage Nutritive Value, and Yield of Contrasting Genotypes of Timothy

“…Leaf weight ratio is reported to decrease with increases in DM yield (Lemaire and Gastal, 1997). Furthermore, NDF concentration is negatively related to LWR (Bélanger and McQueen, 1997, 1999). We hypothesized, therefore, that genotypes with high FDM would have a low LWR, thus a high NDF concentration.…”

Divergent recurrent selection for seedling tiller number in Altai wildrye

“…The nutritive value data presented were based on only one harvest from 1993 so the forage quality difference observed may only reflect that harvest and may not be consistently different between the two groups. Altered carbon allocation patterns that affect the ratio of stems and leaves in the forage may have an effect on nutritive value owing to the greater degree of secondary cell wall in stems as found in timothy (Bélanger and McQueen, 1999). Our observations indicated a greater proportion of reproductive tillers in the forage at the first harvest compared with the second harvest.…”