Mixed Ryegrass Research Articles

Biostimulant effects on the herbage yield and nutritive composition of a mixed ryegrass–clover pasture

Dairy producers are continuously searching for environmentally friendly and economically sustainable alternatives to increase pasture herbage yield and reduce reliance on chemical fertilisers. A possible means to reduce fertiliser reliance is the use of biostimulants. Biostimulants such as fulvic acid and bioflavonoids help to increase N uptake efficiency, thereby increasing herbage quantity and quality. The aim of this study was to determine the effects of a soil application of a carbohydrate-derived fulvic acid and bioflavonoid biostimulant on herbage yield and nutritive composition of a mixed perennial ryegrass–clover pasture. Biostimulant treatment resulted in a lower ryegrass component of the mixed sward, in both winter and summer grazing cycles. However, the nutritive composition and total herbage yield of the pasture were not significantly affected by biostimulant treatment. The treatment did show a tendency to affect total herbage yield within a season. This suggests that total herbage yield could be increased if additional N fertiliser is applied together with a biostimulant soil treatment, although further investigation is needed to confirm this postulation. Biostimulant treatments have the potential to lead to reduced fertiliser inputs on perennial ryegrass–clover pastures as they may increase nutrient uptake efficiency.

Grazing winter and spring wheat crops improves the profitability of prime lamb production in mixed farming systems of Western Australia

Grazing immature cereal crops, particularly different varieties of wheat, has become widely adopted in the high rainfall areas of southern Australia. Recently, there has been growing interest in applying this technology in drier parts of the mixed farming zones of Western Australia. A modelling study was conducted to examine farm business returns with or without the grazing of immature wheat (winter and spring varieties) in different locations of Western Australia (Merredin, Wickepin and Kojonup), representing the low to high rainfall (319–528 mm) cropping regions, respectively. A combination of APSIM (crop simulation model) and GrassGro (pasture and livestock simulation model), were used to evaluate the changes in farm gross margins with the grazing of cereal crops at three locations of Western Australia. The results of the study showed that grazing the two wheat varieties (dual-purpose winter and spring) at the high rainfall location increased the profitability of the livestock enterprise by 2.5 times more than grazing crops at both low rainfall locations (P < 0.05). Across all years and sites, the average supplementary feeding costs were reduced by the inclusion of grazed winter (12%) and spring (2%) wheat crops in the lamb production system. The comparative reduction in the cost of supplementary feeding varied between locations and by crop variety within locations, due to both the frequency and average duration of the grazing of wheat crops in these regions, and the farm-stocking rate that was chosen. Both wheat varieties were grazed frequently at the lowest rainfall site (68% and 30% of years for winter and spring wheat varieties respectively), whereas grazing spring wheat was less frequent at the higher rainfall location and averaged 16% of years due to a greater difference in the relative availability of wheat crops versus pasture for grazing among regions. The grazing model assumed that there were abundant productive mixed ryegrass and subterranean clover pasture in the farming system. Overall, this study suggests that both winter and spring wheat crops are likely to supply green feed during the winter feed shortage (April–July) and reduce supplementary feed requirements for a short period of time in some seasons. The value of grazing crops is likely to be higher on farms with poorer soils and less productive pastures.

Soil microbial response during the phytoremediation of a PAH contaminated soil

The aim of this trial was to quantify and compare the responses of soil microbial communities during the phytoremediation of polycyclic aromatic hydrocarbons (PAHs) in a laboratory trial. The experiment was conducted in 1-kg pots and planted treatments consisted of a mixed ryegrass ( Lolium perenne) and white clover ( Trifolium repens) sward together with a rhizobial inoculum ( Rhizobium leguminosarum bv. trifolii). Throughout the 180-d experiment soil microbial biomass and communities of PAH degraders were monitored. PAH degradation was enhanced in planted treatments that received a rhizobial inoculum. Microbial biomass was enhanced in planted treatments, but there were no significant differences between treatments that had received a rhizobial inoculum and those that had not. However, numbers of PAH degraders were greater in the treatment that had received a rhizobial inoculum.

The effects of forage supplements on the ingestive behaviour and production of dairy cows grazing ryegrass only or mixed ryegrass and white clover pastures

AbstractThe effects on milk yield and feeding behaviour of offering ryegrass silage (r), ryegrass and white clover silage (c), or grass hay (h) supplements were examined for cows grazing a ryegrass pasture (R) or a ryegrass and white clover pasture (C). The chemical composition of the two silages was similar but the hay contained less crude protein. Cows grazing R pasture spent longer feeding on c than r silages, and those consuming the c silage spent less time grazing than those consuming r silage. The cows grazing the C pasture spent longer feeding on r than c silages, and those consuming the r silage spent less time grazing than those consuming c silage. The cows’ intake of hay dry matter (DM) was less than silage DM and it was taken into the mouth at a slower rate, masticated more ana swallowed less frequently than silage. Milk yield and composition were not affected by the type of supplementary forage or pasture type. Thus cows grazing pastures of the two sward types spent longer feeding on forages with dissimilar botanical composition if given the option. However, as this reduced the time that they spend grazing, there was no effect on milk production.

Dinitrogen Fixation Measurements in Alfalfa‐Ryegrass Swards Using Nitrogen‐15 and Influence of the Reference Crop

The accuracy of 15N estimates of N2 fixation may be influenced by the choice of the reference crop, especially in mixed legume‐grass swards, where transfer of fixed N2 from the legume to the reference crop may occur. To investigate this, a 2‐yr field experiment was conducted in a Typic Eutrocrepts soil in Austria to measure N2 fixed in alfalfa (Medicago sativa L.) grown alone or in two seeding ratios with ryegrass (Lolium perenne L.), using pure or mixed sward ryegrass as the reference crop. Alfalfa, on the average, derived over 80% of its N from fixation over the 2‐yr period, equivalent to about 415 kg N/ha. Compared to N2 fixation in pure alfalfa sward, the % N derived from atmospheric N2 (% Ndfa) in alfalfa increased significantly in the mixed sward and even more by increasing the seeding ratio of ryegrass in the mixture. Except for the first harvest, the atom % 15N excess in mixed ryegrass was slightly lower than in the pure grass. These differences in 15SN enrichment were insignificant, suggesting that the possible release of N from alfalfa and subsequent uptake by ryegrass may have been small. The highest proportion of ryegrass N that could have been derived from the legume was estimated to be 16% in the second harvest, equivalent to only 4 kg N/ ha and <10 kg N/ha over the 2 yr. These differences in 15SN enrichments of pure and mixed ryegrass reference plants did not significantly affect the estimates of % Ndfa in alfalfa.

Assessment of root activity of perennial ryegrass and white clover measured using 32phosphorus as influenced by method of isotope placement, irrigation and method of defoliation

AbstractTwo methods of placement of 32P in soil were used to investigate the root activity in perennial ryegrass and mixed ryegrass–white clover swards. The placement of isotope by either horizontal or vertical insertion in the mixed sward had no significant effect on the distribution of root activity with depth, the total dry‐matter yield of herbage or its distribution between ryegrass and clover. At least 90% of the root activity to a depth of 35 cm for both grass and clover occurred within the upper 12.5 cm of the soil profile. Irrigation resulted in a more even distribution of root activity with depth and increased the lateral exploitation of soil P. In the irrigated plot, the root activity of both grass and clover above the line of isotope placement accounted for 40–50% of the total activity at depths to 18.8 cm in contrast to 70–100% in the absence of irrigation. The method of defoliation (cutting versus grazing) had no significant effect on the vertical or lateral distribution of root activity. In unirrigated mixed swards, the root activity of grass in the upper 12.5 cm of the soil profile was greater by a factor of 1.5 to 2 than the contribution of grass to the yield of herbage. With irrigation, however, the distribution of root activity between grass and clover was similar to the contribution of each to the yield of herbage.

Quantitative digestion by sheep of carbohydrates, nitrogen and S-methyl-L-cysteine sulphoxide in diets of fresh kale (Brassica oleracea)

SummaryApparent digestibility of forage kale (cv. Maris Kestrel) was compared with that of mixed perennial ryegrass (0·85) and clover (0·15) herbage in two experiments. In a third experiment measurements were made of the partition of digestion between the reticulo-rumen and post-ruminal regions of the digestive tract in sheep fed kale, using intra-ruminal infusion of inert ruthenium phenanthroline and chromium-EDTA markers and time sequence sampling from the duodenum. Results in Expt 3 were compared with predicted values for a range of ruminant diets, including digestion of fresh perennial ryegrass and white clover.In Expts 1 and 2 the ratio of readily fermentable to structural carbohydrate (CHO) was much higher in kale (2·6–3·2) than in mixed ryegrass and clover herbage (0·6), and showed little difference between kale leaf and stem components. Apparent digestibilities of organic matter (OM), cellulose and hemicellulose were 80–90% for kale diets, varied little with changes in leaf/stem ratio, and were generally slightly higher than for mixed ryegrass and clover herbage. Calculated metabolizable energy (ME) concentrations were 12·0 and 11·7 MJ ME/kg D.M. for kale and mixed ryegrass and clover respectively.Despite large intakes of water-soluble CHO and pectins in kale-fed sheep in Expt 3, duodenal flows were small and respectively 92 and 98% of the total amounts digested were digested in the rumen. Ruminal cellulose digestion (95% total digested) was as predicted for normal ruminant diets, but less hemicellulose was digested in the rumen (71% total digested) than predicted. Total N flow at the duodenum was 5 g/day less than N intake, and respectively 27 and 66% of the N apparently digested was accounted for as total N absorption from the rumen and post-ruminal absorption of NAN. Calculated absorption of amino acids from the small intestine was less for the kale diet (14% ME intake) than for diets of fresh perennial ryegrass and white clover (20% ME intake). Possible reasons are that 10% more of the OM ingested was digested in the rumens of sheep fed kale than was predicted, that the ratio of dietary total N/100 g digestible OM was much less for kale (3·7) than for perennial ryegrass and white clover (5·6) diets, and that protein formed a lower proportion of the total N in kale diets (75%) than in diets of ryegrass and clover (90%). Despite 3·3 g of S-methyl-L-cysteine sulphoxide (SMCO) being consumed per day, none was detected in either rumen or duodenal contents or in faeces.In was concluded that complete conversion of SMCO to dimethyl disulphide occurred in the rumen, that dimethyl disulphide may have caused the depression in ruminal digestion of hemicellulose, and that the digestion products of kale are deficient in absorbed amino acids relative to other forms of energy, thus explaining responses to essential amino acid supplementation in lambs grazing kale.

Motility of the reticulum and rumen of sheep given juice-extracted pasture.

1. Sheep were fed on different diets of juice-extracted herbage to determine what effect juice-extraction had on reticulo-rumen motility. 2. The frequency of A and B sequences of contraction of the reticulo-rumen were recorded during eating, rumination and inactivity for continuous periods of 24-72 h by using integrated electromyograms obtained from electrodes implanted in the musculature of the reticulum and cranial dorsal rumen. 3. Animals were fed on herbage in which approximately 200 g/kg drug matter had been removed in juice extracted from ryegrass (Lolium perenne), white clover (Trifolium repens), mixed ryegrass-white clover and lucerne (Medicago sativa). 4. Over all the frequency of A sequences of contraction did not differ in animals fed on pressed herbage or the unpressed material from which it was derived, although it was slower during rumination on some of the pressed material. In contrast, the frequency of B sequences was higher on the pressed material. The frequencies of contraction of A and B sequences in animals fed on pressed herbage was related to the activity of the animals in the order eating greater than rumination greater than inactivity. 5. Changes in reticulo-rumen motility due to juice extraction were small and the frequencies of A and B sequences of contraction in sheep fed on pressed herbage were in the range encountered in ruminants consuming more conventional foods.