Canopy morphology and nutritional quality traits as potential grazing value indicators for Lolium perenne varieties

Abstract

Twelve perennial ryegrass (Lolium perenne L.) varieties of different ploidy and maturity classifications were compared under a frequent cutting management in their second harvest year, equivalent to the simulated rotational grazing system employed in UK testing protocols. Varietal differences in canopy structure (proportion of lamina, green leaf mass, sward surface height, extended tiller height, bulk density) and in herbage nutritive value factors (water-soluble carbohydrate content and proportion of linoleic and α-linolenic fatty acids) were assessed and their importance evaluated with reference to total herbage production. Significant variety variation (P<0·001) was recorded in the annual means of all the canopy structure characteristics. Significant differences associated with ploidy were also recorded, with tetraploid varieties having significantly higher values than diploids in most plant characters, indicating better intake characteristics for these grasses. Temporal patterns of variation associated with maturity were also observed in several characters, thus making it impossible to designate a single assessment that would be representative of the annual ranking of varieties. Water-soluble carbohydrate concentration differed significantly (P<0·001) between varieties and although the tetraploids tended to have high contents, the highest value of all was recorded in a diploid variety, which had been selectively bred for this trait. The varieties did not differ in total lipid content but there were significant differences in the proportion of linoleic acid between varieties (P<0·001) while the proportion of α-linolenic acid differed between varieties (P<0·001), ploidy (P<0·001) and maturity (P<0·05) classes.Overall evaluation of the extensive variety variation highlighted the need for better quantification of animal responses to differences of these magnitudes, before the high workload of including them in routine variety testing protocols could be justified. Potential for breeding improvement in these factors was also indicated and the future prospects for their use in farmer decision support systems was considered.

Effect of perennial ryegrass (Lolium perenne L.) cultivars on the milk yield of grazing dairy cows

“…WSC is a trait that varies between cultivars (Gilliland et al, 2002) and ranged from 143 to 253 g/kg DM in the current study. The levels peaked during the reproductive growth phase and declined as the season progressed, which is in agreement with Miller et al (2001).…”

“…In order to maximise GDMI, grazing animals need to be offered a sward with characteristics that allow rapid consumption -E-mail: michael.odonovan@teagasc.ie (O'Donovan et al, 2010). Sward structural differences between cultivars have been shown to influence herbage intake (Gilliland et al, 2002;Smit et al, 2005a) and may be more important than organic matter digestibility (OMD) in determining GDMI and milk yield (O'Donovan and Delaby, 2005). For example, the voluntary GDMI of the leaf fraction is 20% higher than that of the stem fraction (Laredo and Minson, 1975), suggesting that variations in cultivar leaf proportion will influence intake and animal performance (Gowen et al, 2003).…”

Efecto de la edad de rebrote sobre el perfil de ácidos grasos en gramíneas tropicales

“…En otros estudios, el pasto Ryegrass presentó la mayor concentración de ácido linolénico (61 %), seguido por el pasto Festuca (55,9 %), el Azul orchoro (51,8 %) y el Timothy (49,9 %) (Glasser et al 2013). También se han reportado diferencias en las proporciones de ácido linoleico y linolénico (C18:3) en los AG de 12 variedades de Ryegrass (Gilliland et al 2002).…”

Environmental and Genetic Variation for Water Soluble Carbohydrate Content in Cool Season Forage Grasses

“…A variation of 20% for WSC concentration among six diploid ryegrasses was found to be consistent over several years (Smit, 2006), the largest variation among cultivars was found during summer, in July and August. Tetraploid cultivars generally had a higher WSC concentration than diploid cultivars (Smith et al 2001;Gilliland et al 2002). DMD concentration declined during summer due to the influence of higher temperatures, however, high WSC lines exhibited fewer declines in DMD than the lines that did not accumulate as much WSC.…”

“…There is, however, indirect evidence that higher WSC in ryegrass may result in improved animal performance (Lee et al, 2001;Evans et al, 2011;Miller et al, 2001). Tetraploid ryegrass varieties have higher levels of WSC compared to diploids (Jung et al, 1996;Smith et al 2001;Gilliland et al 2002). There are two large scale animal production trials in which tetraploid and diploid varieties were compared (Castle and Watson, 1971;Connolly et al, 1977).…”