The in Vitro Digestibility and Protein Content of Leaf and Stem Portions of Forages

Bélanger, G. and McQueen, R. E. 1997. Leaf and stem nutritive value of timothy cultivars differing in maturity. Can. J. Plant Sci. 77: 237-245. The nutritive value of herbage is a function of the nutritive value of its component leaves and stems and their proportion in the herbage. A previous study indicated that the proportion of leaves in the herbage did not explain entirely the differences in in vitro true digestibility and NDF concentrations between early and late-maturing timothy (Phleum pratense L.) cultivars. It was therefore hypothesized that the leaves and stems of early and late-maturing cultivars differ in nutritive value. The evolution of leaf and stem nutritive value of field-grown timothy cultivars differing in maturity, and the relationships between parameters of leaf and stem nutritive value, and the leaf to weight ratio (LWR) were studied during primary growth in two experiments. On a given date, stems of early-maturing cultivars had in vitro true digestibilities of dry matter and cell wall up to 61 g kg -1 DM and 71 g kg -1 DM lower that those of late-maturing cultivars, respectively. The NDF concentration of stems of early-maturing cultivars was up to 32 g kg -1 DM greater than that of late-maturing cultivars. There were no cultivar differences in leaf in vitro true digestibilities of dry matter and cell wall, and NDF concentration on a given date. At a given LWR, however, the leaves and stems of early-maturing cultivars had greater in vitro true digestibilities of dry matter and cell wall, and a lower NDF concentration than those of late-maturing cultivars. Our results indicate that differences in herbage nutritive value at a given stage of maturity between early-and late-maturing timothy cultivars is explained by a greater nutritive value of leaves and stems of the early-maturing cultivars.Key words: Phleum pratense L., timothy, cultivar, digestibility, cell wall, leaf, stem Bélanger, G. and McQueen, R. E. 1997. Valeur nutritive des feuilles et des tiges de cultivars de fléole des prés ayant des maturités différentes. Can. J. Plant Sci. 77: 237-245. La valeur nutritive des fourrages dépend de la valeur nutritive des feuilles et des tiges, et de leurs proportions respectives dans les fourrages. Une étude précédente a démontré que la proportion des feuilles n'expliquait pas entièrement les différences de digestibilité in vitro de la matière sèche et de teneur en NDF entre les cultivars hâtifs et tardifs de fléole des prés (Phleum pratense L.). Ainsi, nous avons émis l'hypothèse que les cultivars hâtifs et tardifs diffèrent également par la valeur nutritive de leurs feuilles et tiges. L'évolution de la valeur nutritive des feuilles et tiges de cultivars hâtifs et tardifs de fléole des prés cultivée au champ, et la relation entre les paramètres de valeur nutritive des feuilles et tiges d'une part et la proportion de feuilles dans la biomasse d'autre part ont été étudiées au cours de deux expérimentations réalisées pendant la croissance primaire. A une date donnée, les tiges des cultivars hâtifs...

Section: Results and Discussion Relationship Of Nutritive Value With supporting

confidence: 82%

Section: Mot Clésmentioning

confidence: 99%

Leaf and stem nutritive value of timothy cultivars differing in maturity

Bélanger¹,

McQueen²

1997

“…This agrees with Mowat et al (1965) and Nelson and Moser (1994). By the end of the regrowth corresponding to a normal harvesting date at the For personal use only.…”

Section: Seasonal Effectsupporting

confidence: 82%

“…This supports the findings from several studies (Buxton and Casler 1993). Contrary to our speculation in a previous paper (Bélanger and McQueen 1998) and to results reported by Terry and Tilley (1964) and Mowat et al (1965), the present results indicate that the nutritive value of leaf blades in spring was greater than that of sheaths at the early vegetative stage (Tables 2 and 3).…”

Section: Seasonal Effectcontrasting

confidence: 57%

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

Bélanger¹,

McQueen²

1999

. 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...

“…Mots clés: Poa pratensis L., qualité fourragère, graminée vivace, feuille, tige Herbage quality of cool-season grasses declines with advancing maturation. Herbage digestibility and CP concentration decrease, whereas fiber and lignin concentrations increase with maturation (Pritchard et al 1963;Mowat et al 1965). The decline in whole herbage quality of smooth bromegrass (Bromus inermis Leyss) with maturation was attributed to a decrease in the leaf/stem mass ratio as well as to changes in the quality of leaf and stem fractions.…”

mentioning

confidence: 99%

Maturation effects on forage quality of Kentucky bluegrass

Hockensmith¹,

Marten²,

Halgerson³

1997

quality of Kentucky bluegrass. Can. J. Plant Sci. 77: 75-80. Kentucky bluegrass (Poa pratensis L.) is an important constituent of many permanent pastures in the northern United States and is an important source of livestock feed, but there is a paucity of information on its forage quality. The objective of this research was to assess changes with maturity in forage quality of whole herbage, leaves, and stems of Kentucky bluegrass compared with other important cool-season forage grasses. Kentucky bluegrass, orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinaceae L.), smooth bromegrass (Bromus inermis Leyss), timothy (Phleum pratense L.), and tall fescue (Festuca arundinacea Schreb) were sampled weekly beginning in mid-May until each species reached milk stage. Kentucky bluegrass had the highest or was among the grasses with the highest average leaf percentage, and leaf, stem, and whole herbage neutral detergent fiber (NDF) and acid detergent lignin (ADL) concentrations; and lowest average whole herbage, leaf, and stem in vitro digestible dry matter (IVDDM) concentrations compared with tall growing species. Kentucky bluegrass also had the slowest rates of change in leaf and stem concentration and in whole herbage IVDDM and NDF concentrations with maturity. Leaf concentration was negatively correlated with herbage NDF and ADL concentration, but was not correlated with herbage IVDDM and CP concentration. Relative to tall growing cool season grasses, Kentucky bluegrass is leafier, but it has poorer forage digestibility. Mots clés: Poa pratensis L., qualité fourragère, graminée vivace, feuille, tige Herbage quality of cool-season grasses declines with advancing maturation. Herbage digestibility and CP concentration decrease, whereas fiber and lignin concentrations increase with maturation (Pritchard et al. 1963;Mowat et al. 1965). The decline in whole herbage quality of smooth bromegrass (Bromus inermis Leyss) with maturation was attributed to a decrease in the leaf/stem mass ratio as well as to changes in the quality of leaf and stem fractions. Leaves and stems of tall growing grasses may have similar digestibility when vegetative, but by heading, stems typically have lower digestibility and CP concentration and higher lignin and fiber concentration than leaves (Pritchard et al. 1963;Smith 1973;Sanderson and Wedin 1989). Species differences in leaf and stem quality at post-heading stages result, in part, from varying rates of decline in quality of each fraction (Buxton and Marten 1989). Sanderson and Wedin (1989) reported that IVDDM of smooth bromegrass leaf blades declined 3 g kg -1 for each phenological stage while stems declined 7 g kg -1 for each phenological stage.The aforementioned research on relationships of maturity with forage quality is primarily focused on tall growing 75 Abbreviations: ADL, acid detergent lignin; CP, crude protein; IVDDM, in vitro digestible dry matter; NDF, neutral detergent fiber; NIRS, near infrared reflectance spectroscopy Can. J. Plant Sci. Downloaded from www....