scholarly journals Pasture resilience reflects differences in root and shoot responses to defoliation, and water and nitrogen deficits

2021 ◽  
Vol 17 ◽  
Author(s):  
Derrick Moot ◽  
Alistair Black ◽  
Eric Lyons ◽  
Lucy Egan ◽  
Rainer Hofmann
Keyword(s):  
Leaf Area ◽  
Perennial Ryegrass ◽  
Water Soluble ◽  
Grass Species ◽  
Soluble Carbohydrate ◽  
Plant Responses ◽  
Water Deficits ◽  
C And N ◽  
Response To Water ◽  
Water Soluble Carbohydrate

The yield of a pasture is directly proportional to the amount of light plants intercept and allocate to different organs. When plants are carbon (C) limited, due to defoliation, they allocate more C preferentially to shoots to restore leaf area. In contrast, water and nitrogen (N) limitations lead to a greater allocation of C to roots. Changes in the root:shoot ratio therefore reflect changes in C and N partitioning and indicate their relative priority. A major factor that influences plant responses to stress is their ability to store and remobilise reserves to restore leaf area. Species with tap roots, like lucerne, have a large potential C and N storage capacity that is utilised seasonally for storage and remobilisation. This has been used to develop seasonally based grazing management rules. Similarly, recommendations to graze perennial ryegrass at the 2- or 3-leaf stage are based on the balance between maximizing growth rates and the need to replenish water-soluble carbohydrate reserves. However, perennial ryegrass has lower levels of perennial reserves than other grass species. This reduces its resilience to concurrent water deficits or N deficiency. Under these conditions maintaining the recommended 3-leaf grazing intervals and/or leaving higher post-grazing pasture masses are recommended to assist canopy recovery. Other grass species, such as cocksfoot and tall fescue, provide more resilience, particularly in response to water deficits.

Characterisation of the WSC fraction of six species of temperate pasture grass

2004 ◽  
Vol 32 ◽  
pp. 247-248
Author(s):  
J. C. Ince ◽  
A. C. Longland ◽  
A. J. Cairns ◽  
M. Moore–Colyer
Keyword(s):  
Perennial Ryegrass ◽  
Water Soluble ◽  
Italian Ryegrass ◽  
Soluble Carbohydrate ◽  
Meadow Fescue ◽  
Pasture Grass ◽  
Pasture Grasses ◽  
Optimal Health ◽  
Water Soluble Carbohydrate ◽  
Field Plots

The carbohydrate (CHO) fraction of pasture grasses is a major source of energy for many domestic herbivores. However, the amounts, and types, of the water–soluble carbohydrate (WSC) fraction (i.e. glucose, fructose, sucrose, and polymers of sucrose and fructose, the fructans) present in such grasses, varies with species and environmental conditions. As the WSC constitute a highly digestible, energy yielding fraction of grasses, it is important to be able to measure their levels in a sward so that the diets of pastured animals may be designed to elicit optimal health and productivity. The aim of this study was to characterise the WSC profile of six UK pasture grasses, and to develop a technique for extracting the fructan portion of the WSC.Six species of UK pasture grasses [Cocksfoot (C), Timothy (T), Meadow Fescue (M), Italian Ryegrass (IR), Perennial Ryegrass (PR) and Hybrid Ryegrass (HR)] were grown in experimental field plots at IGER.

Methane emissions differ between sheep offered a conventional diploid, a high-sugar diploid or a tetraploid perennial ryegrass cultivar at two allowances at three times of the year

2018 ◽  
Vol 58 (6) ◽  
pp. 1043 ◽  
Author(s):  
A. Jonker ◽  
G. Molano ◽  
E. Sandoval ◽  
P. S. Taylor ◽  
C. Antwi ◽  
...  
Keyword(s):  
Perennial Ryegrass ◽  
Dry Matter ◽  
Early Spring ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Ch4 Emissions ◽  
High Sugar ◽  
Elevated Water ◽  
Water Soluble Carbohydrate ◽  
Male Sheep

Elevated water-soluble carbohydrate (WSC) concentration in the diet may affect rumen fermentation and consequently reduce methane (CH4) emissions. The objective of the present study was to determine CH4 emissions from male sheep (8 per treatment) in respiration chambers for 48 h and fed either a conventional diploid (CRG), a high-sugar diploid (HSG) or a tetraploid (TRG) perennial ryegrass cultivar, each offered at 0.7 or 1.0 kg dry matter (DM)/day during periods in early spring 2013 (P1), early autumn 2014 (P2) and late spring 2014 (P3). There was a significant (P < 0.001) interaction between cultivar and period for CH4 yield (g/kg DM intake). In P1 yield was 9% lower (P = 0.007) for sheep fed HSG than for sheep fed CRG or TRG, in P2 yield was 16% lower (P < 0.001) for sheep fed TRG than that for sheep fed CRG or HSG, and in P3 yield was 15% lower (P < 0.001) for sheep fed TRG than that for sheep fed CRG, with HSG-fed sheep being intermediate and not significantly different from either CRG or TRG. Despite there being a cultivar × period interaction, overall, CH4 yield was lower for sheep fed HSG or TRG than for sheep fed CRG (P < 0.001). There were no cultivar × level of feed offer interactions and, overall, yield of CH4 was 9% higher (P = 0.003) for sheep offered 0.7 than for sheep offered 1.0 kg DM/day. In each period, one or other of the high-WSC diploid (HSG) or tetraploid cultivars (TRG) gave lower CH4 yields than did the control diploid (CRG), suggesting that CH4 yield is reduced by characteristics of these cultivars. However, the effect was not consistently associated with either cultivar and could not be attributed to higher forage water-soluble carbohydrate concentrations.

The distribution of errors associated with genotype and environment during the prediction of the water-soluble carbohydrate concentration of perennial ryegrass cultivars using near infrared reflectance spectroscopy

2000 ◽  
Vol 51 (4) ◽  
pp. 481 ◽  
Author(s):  
K. F. Smith ◽  
G. A. Kearney
Keyword(s):  
Perennial Ryegrass ◽  
Near Infrared ◽  
Reflectance Spectroscopy ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Infrared Reflectance ◽  
Near Infrared Reflectance Spectroscopy ◽  
Near Infrared Reflectance ◽  
Infrared Reflectance Spectroscopy ◽  
Water Soluble Carbohydrate

Significant deviations associated with site or cultivars within sites were detected in 4 of 6 independent near infrared reflectance spectroscopy (NIRS) calibrations developed to predict water-soluble carbohydrate (WSC) concentrations in perennial ryegrass herbage harvested from 2 sites. These effects were observed both when calibration subsets were selected on the basis of spectral characteristics, and when calibration sets were balanced with respect to a priori knowledge of the structure of the data set. However, there were also instances when non-random deviations were not significant, demonstrating that it was possible to develop broadly based NIRS calibrations to predict WSC in perennial ryegrass. Deviations between NIRS predictions and reference values should be monitored, with reference to the structure of the experiment from which the samples were derived, before NIRS estimates of WSC concentration are used in agronomy or plant breeding.

scholarly journals Sheep performance on perennial ryegrass cultivars differing in concentration of water-soluble carbohydrate

2015 ◽  
Vol 77 ◽  
pp. 123-130 ◽  
Author(s):  
G.P. Cosgrove ◽  
P.S. Taylor ◽  
A. Jonker
Keyword(s):  
Perennial Ryegrass ◽  
Average Daily Gain ◽  
Continuous Variable ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Nitrogen Emissions ◽  
Economic Output ◽  
High Sugar ◽  
Water Soluble Carbohydrate ◽  
Daily Gain

High-sugar perennial ryegrass cultivars (HSG) selected for higher concentrations of water-soluble carbohydrate may enhance animal production and reduce emissions of methane and nitrogen. Assessing the effects on economic output and environmental footprint is most robust when related to production per unit of land. Average daily gain (ADG) and liveweight gain per hectare (LWG/ha) of sheep grazing a high-sugar perennial ryegrass cultivar, a diploid perennial ryegrass and a tetraploid perennial ryegrass were compared during measurement periods conducted in spring (84 days duration), autumn (99 days) and late springsummer (160 days). Continuous variable stocking was used, and stocking rate adjusted to maintain a target sward surface height of 6 cm. Average daily gain was higher (P=0.003) on the HSG than on either control in late spring-summer and higher on the tetraploid control than on the HSG or the diploid control in autumn (P=0.04), but the higher ADGs did not translate to significantly higher LWG/ha. These results can inform farmers on cultivar choice and support analysis of methane and nitrogen emissions on an intensity basis for inventory and regulatory purposes. Key words: water-soluble carbohydrate, perennial ryegrasses, high-sugar ryegrass, average daily gain, liveweight gain

Quantitative digestion of fresh herbage by sheep:V. The digestion of four herbages and prediction of sites of digestion

1979 ◽  
Vol 92 (3) ◽  
pp. 605-616 ◽  
Author(s):  
M. J. Ulyatt ◽  
A. R. Egan
Keyword(s):  
Organic Matter ◽  
Small Intestine ◽  
Organic Acids ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Crude Protein ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Water Soluble Carbohydrate ◽  
Dietary Origin

SUMMARYThe extents and sites of digestion of organic matter (OM), and its constituent watersoluble carbohydrates, organic acids, pectin, cellulose, hemicellulose and crude protein have been studied in sheep prepared with re-entrant duodenal cannulas and fed four fresh herbage diets, Ruanui perennial ryegrass, Tama Westerwolds ryegrass, Pitau white clover and Fakir sainfoin, at each of two levels of intake.The water-soluble carbohydrate, organic acids and pectin of all diets were almost completely digested within the rumen. Some 10% of water soluble carbohydrate reached the duodenum on each diet, though this may not have been of dietary origin. Only on legume diets, where pectin concentration was higher, did measurable amounts of pectin reach the intestine, accounting for some 5% of the pectin.Hemicellulose and cellulose digestibilities differed between diets, being lowest for sainfoin, and next lowest for clover. Between 79 and 94% of digestible hemicellulose was digested in the stomach, but diet and intake had no significant effect on this partition. Of the digestible cellulose, 87–97% was digested in the stomach.Digestibility of N was lowest for sainfoin and highest for Tama ryegrass. There were no significant differences between herbage species or intake in the percentage of digested N digested in the stomach or intestines. The tannin contained in sainfoin had no effect on nitrogen digestion.Data from this and other studies reported in the literature were examined as a basis for establishing prediction equations whereby the partition of digestion of the major carbohydrate and nitrogenous constituents in stomach and intestines might be estimated from data obtainable from standard digestibility trials. Regressions were developed for predicting the amounts of OM, cellulose, and hemicellulose digested in the stomach. There are not yet enough suitable data available to predict the amount of nitrogen entering the small intestine.

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