Leaf and stem dry matter digestibility and ruminal undegradable proteins of alfalfa cultivars

Abstract

R. 2002. Leaf and stem dry matter digestibility and ruminal undegradable proteins of alfalfa cultivars. Can. J. Plant Sci. 82: 383-393. Increased dry matter digestibility and ruminal undegradable protein (RUP) concentration are traits highly ranked to improve the nutritive value of forage legumes. Whole-plant, leaf, and stem samples of 27 alfalfa cultivars grown in eastern Canada were analysed for total nitrogen (TN), in vitro RUP, and in vitro dry matter digestibility (IVDMD). The objectives were to determine if significant variation exists among these cultivars, and to establish the relationship between nutritive value parameters of leaves and stems, and those of whole plants. Cultivars were seeded in triplicate on 2 consecutive years and evaluated during the 2 subsequent production years with two harvests per year. There were significant differences among cultivars in IVDMD of stems and plants in spring growth and summer regrowth. Cultivar differences in leaf IVDMD were significant only in spring growth, but this variation was negligible in practical terms. Cultivars with high forage IVDMD also had high stem IVDMD and this relationship was stronger in summer regrowth. Alfalfa plant IVDMD is a function of stem digestibility and the leaf weight ratio (LWR). Cultivar differences were significant for plant TN in spring growth and summer regrowth, and for stem TN in spring growth only. Leaf (270 to 306 g kg -1 TN) and stem (242 to 287 g kg -1 TN) RUP concentrations varied among cultivars in spring growth. Cultivars with high stem RUP also had high leaf RUP concentration but differences in plant RUP were not always attributed to leaf and stem RUP. The RUP concentration was on average 10% higher in leaves than in stems in spring growth, and this difference reached 15% in summer regrowth. The LWR varied among cultivars in spring growth and summer regrowth, and it was positively related to plant RUP in spring growth. Improved whole-plant RUP concentration is unlikely to be achieved by simply selecting for high RUP in leaves or stems; LWR has a principal role in determining alfalfa plant RUP concentration.Key words: Dry matter digestibility, ruminal undegradable proteins, alfalfa, genetic variation, stems, leaves Tremblay, G. F., Bélanger, G., McRae, K. B. et Michaud, R. 2002. Digestibilité de la matière sèche et protéines non dégrad-ables dans le rumen des feuilles et des tiges de cultivars de luzerne. Can. J. Plant Sci. 82: 383-393. Une digestibilité de la matière sèche et une concentration en protéines non dégradables au niveau du rumen (RUP) élevées sont parmi les premiers critères permettant d'améliorer la valeur nutritive des légumineuses fourragères. Les plantes, les feuilles et les tiges de 27 cultivars de luzerne cultivés dans l'est du Canada ont été analysés pour leur concentration en azote total (TN) et en RUP, ainsi que pour la digestibilité in vitro de la matière sèche (IVDMD). Le but était de déterminer s'il existe une variation significative entre les cultivars, et d'établir la relation entre les paramè...

Biomass Yield Potential and Herbage Quality of Alfalfa (Medicago Sativa L.) Genotypes in the Central Highland of Ethiopia

“…The significant difference (P<0.05) among the tested genotypes was in agreement with (Diriba et al, 2014) and in disparity with others finding (Mekuanint et al, 2015). Volenec and Cherney (1990) reported significant differences in IVDMD among alfalfa cultivars and these differences were indicated to be associated with variation in digestibility of the stem fraction (Tremblay et al, 2002). A significant difference among 14 alfalfa varieties was also reported for IVDMD, with values ranging from 59 to 66% (Kamalak et al, 2005), which indeed were much lower than those recorded in the present work.…”

Fatty acids in forages. I. Factors affecting concentrations

“…Bélanger and McQueen (1998) reported that the proportion of leaves in timothy was higher in summer regrowth (LWR = 0.5) than in spring growth (LWR = 0.3). In alfalfa, Tremblay et al (2002) reported that the LWR of 27 cultivars seeded in three replicates during 2 yr and harvested during the 2 subsequent production years was lower in spring growth (0.39) than in summer regrowth (0.45). Onstad and Fick (1983) also reported a lower LWR in spring than in regrowth of alfalfa at the same physiological age.…”

In situ rumen degradation kinetics of timothy and alfalfa as affected by cultivar and stage of maturity

“…Numerous studies (Jung and Allen 1995;Ayres et al 1998;Elizalde et al 1999;Ferdinandez and Coulman 2001;Lyon et al 2001) have shown that yield and nutritional values of forages are affected by growth stage, forage species, cultivar (Kunelius 1990;Griffin et al 1994;Lundvall et al 1994;Tremblay et al 2000Tremblay et al , 2002Tremblay et al , 2003, soil type (Aumont and Salas 1996), climate conditions (e.g., rainfall, temperature) (Minson and McLeod 1970;Mathison et al 1996) and growing conditions (Cox et al 1994). In Canada, Kunelius (1990) reported dry matter production, fiber composition, and plant characteristics of cool-season grasses including timothy under two harvest systems.…”

“…Bélanger and McQueen (1996) reported the differences in digestibility and cell wall concentration of early-and late-maturing timothy (Phleym pratense L.) cultivars. Tremblay et al (2000Tremblay et al ( , 2002Tremblay et al ( , 2003 reported significant effects of alfalfa cultivars on in vitro ruminal undegradable proteins (Tremblay et al 2000), leaf and stem dry matter digestibility and ruminal undegradable proteins (Tremblay et al 2002) and protein fractions (Tremblay et al 2003). Information, however, is lacking on rumen degradation characteristics of different cultivars of alfalfa and timothy grown under the climate conditions of western Canada.…”