Differences in the crude protein fractions of lucerne leaves and stems under different stand structures

Abstract

Protein degradability in forage legumes is of global importance because utilization efficiency of forage has economic and environmental consequences. However, there are no published studies on the effect of legume stand structure on differences in crude protein (CP) fractions. The main objective of the present research was therefore to investigate differences in CP fractions in leaves and stems of lucerne (Medicago sativa L.) during the growing season. Stand traits were measured over 2 years, and forage was sampled at the early bud and early flower stages in the first, second and third cuts. Stems had significantly higher concentrations (in g kg−1 CP) of non‐protein (fraction A: 430 g kg−1 CP) and indigestible nitrogen (fraction C: 92 g kg−1 CP) than leaves and had lower relative content of true protein (fraction B: 478 g kg−1 CP). In the total forage (stems and leaves combined), about 80% of the variation in CP fractions was explained by year, cut and maturity. Year was the most important factor, particularly for the B fractions. Cut was the second‐most important factor; its main effect was that the relative abundance of fraction A declined from 394 g kg−1 CP in the first cut to 293 in g kg−1 CP the third cut. Maturity increased the amounts of indigestible fraction C and protein fractions B1 and B3. This was associated with the leaf weight ratio, which had an inverse relationship with maximal stem length and dry matter yield. Variation partitioning showed that 75% of CP fraction variability associated with cut, maturity and year could be explained by the evaluated stand traits. This research has highlighted the need to consider plant morphological traits when legume CP fractions are evaluated.

Fatty acid profile in two berseem clover (Trifolium alexandrinum L.) cultivars: Preliminary study of the effect of part of plant and phenological stage

“…As expected, the DM, NDFom, ADFom and ADL of leaves and stems increased at the REP stage if compared with GW stage in agreement with the findings of Rebol e et al (2004) probably because the weather was warmer and drier as also observed by Molle et al (2003). On the other hand, CP, EE and WSC showed higher levels during GW if compared with REP stage partly in agreement with Hakl et al (2016) in their study on alfalfa chemical composition. Soluble protein (NPN + BSP) were higher (P < 0.05) in REP than in GW stage, also in agreement with Hakl et al (2016).…”

“…Soluble protein (NPN + BSP) were higher ( P < 0.05) in REP than in GW stage, also in agreement with Hakl et al . (). The magnitude of change in macro chemical composition was much higher for WSC in leaves whereas stems showed greater changes in DM, NDFom, ADFom, Ash and CP contents.…”

“…On the other hand, CP, EE and WSC showed higher levels during GW if compared with REP stage partly in agreement with Hakl et al . () in their study on alfalfa chemical composition. Soluble protein (NPN + BSP) were higher ( P < 0.05) in REP than in GW stage, also in agreement with Hakl et al .…”

Effects of plant architecture and drought stress level on lucerne forage quality

“…Although differences in quality can be found between basal and apical portions of the stem throughout the growing season (Christian, Jones, & Freer, ), the quality of the stem as a whole organ is a matter of concern in the improvement of feeding value (Julier & Huyghe, ; Lenssen et al., ), given its large proportion by weight in lucerne hay. Recent research has also shown that leaves and stems differ in crude protein fractions, with stems showing higher concentrations of non‐protein and indigestible nitrogen, and lower content of true protein fraction than leaves (Hakl, Fuksa, Konečná, & Šantrůček, ). A specific selection for stem quality was supported by a recent genomewide association study, which suggested substantially different genetic control of forage quality traits in lucerne stems and leaves (Biazzi et al., unpublished data).…”

Estimation of extractable protein in botanical fractions of legume and grass species

“…Previous studies have determined the protein fractions of tropical grasses (Johnson, Reiling, Mislevy, & Hall, 2001), legumes (Kirchhof, Eisner, Gierus, & S€ udekum, 2010), grass-legume mixtures (Krawutschke et al, 2013), different varieties of legumes (Yu, Christensen, McKinnon, & Markert, 2003), botanical fractions of lucerne (Hakl, Fuksa, Kone cn a, & Santr u cek, 2016) and perennial ryegrass (Hoekstra, Struik, Lantinga, van Amburgh, & Schulte, 2008 Figure 1. The procedure for the biomass yield determination was previously described by Solati et al (2017).…”