The effect of selenium on infertility in ewes grazing improved pastures

1970 ◽  
Vol 10 (47) ◽  
pp. 672 ◽  
Author(s):  
KO Godwin ◽  
RE Kuchel ◽  
RA Buckley

Trials conducted in South Australia, in an area where pasture improvement by means of the introduction of subterranean clovers has been practised for 10-15 years, have shown a significant improvement in fertility, in ewes treated with selenium. Analysis of all pastures grazed, and of whole blood of stock grazing them, indicated that the selenium status of the feed and of the animals was low. Phyto-oestrogen assays showed the presence of the isoflavones formononetin, genistein, and biochanin A, in the subterranean clover, which was mainly the cultivar Yarloop (Trifolium subterraneum L. var. Yarloop). Administration of selenium four to eight weeks before mating, given either as an oral dose of sodium selenite, or supplied in the form of an intraruminal selenium pellet containing elemental selenium and iron, led to an improvement in fertility; in some cases from 49 to 76 per cent. Also, lamb mortality was reduced by selenium administration to the ewes. There were differences due to selenium administration (P<0.001). Ewe fertility differed between pastures designated 'oestrogenic' and 'non-oestrogenic' (P<0.05). But no interaction between selenium and the presence of phyto-oestrogens could be shown by these experiments. The results are discussed in relation to the problem of infertility associated with the grazing of improved pastures

1992 ◽  
Vol 32 (5) ◽  
pp. 611 ◽  
Author(s):  
AD Craig

Two cultivars of subterranean clover, Trikkala and Mt Barker, were continuously grazed by Merino ewes and lambs at 3 stocking rates (8, 13, and 18 ewes/ha) from 1976 to 198 1. The pastures were assessed for clover seedling density, pasture availability and composition, seed reserves, and oestrogen content. Trikkala produced consistently higher seed yields than Mt Barker, with an average yield 3.36 times that of Mt Barker by January 1981 (1178 v. 350 kg/ka). The higher Trikkala seed yields resulted in improved clover seedling densities and increased amounts of clover in the pastures. At the last assessment (8 September 1980) there was an average of 3.15 times more clover in the Trikkala pastures than in the Mt Barker pastures (469 v. 149 kg/ha). Trikkala produced more total available pasture than Mt Barker, at several samplings, because the contribution of subterranean clover to total available pasture was greater after September 1978. The formononetin, genistein and biochanin A content of both cultivars decreased with increasing stocking rate. The most consistent effects were observed in genistein content, with reductions occurring in 7 of the 11 samplings.


1979 ◽  
Vol 19 (101) ◽  
pp. 689 ◽  
Author(s):  
SK Walker ◽  
GP Hall ◽  
DH Smith ◽  
RW Ponzoni ◽  
GJ Judson

The responses in liveweight, wool weight and survival, to selenium supplementation, were studied in young sheep from weaning to yearling age. The experiment was conducted over three years. In the first year, one sodium selenite supplementation rate was used (total dose 46.5 mg). During the following two years two supplementation rates were administered (total doses 46.5 mg and 93 mg). Mean concentrations of selenium in whole blood in unsupplemented sheep varied from 0.19-0.56 pmol l-l and from 0.20-0.44 pmol l-1 in the two years in which concentrations were measured. Supplementation, which commenced at lamb marking, increased the selenium concentration in sheep at weaning and thereafter. Selenium supplementation improved the break-of-season weight (P < 0.01) and yearling weight (P < 0.01 ) but not weaning weight (0.05 < P < 0.1 ). Hogget fleece weight was improved (P < 0.01 ) and mortality reduced (P < 0.01) by selenium supplementation. There was a treatment x year interaction in mortality rates (P < 0.01 ). There were no significant differences between the two supplementation rates


2001 ◽  
Vol 41 (2) ◽  
pp. 187 ◽  
Author(s):  
R. Aldaoud ◽  
W. Guppy ◽  
L. Callinan ◽  
S. F. Flett ◽  
K. A. Wratten ◽  
...  

In 1995–96, a survey of soil samples from subterranean clover (Trifolium subterraneum L.) paddocks was conducted across Victoria, South Australia, New South Wales and Western Australia, to determine the distribution and the prevalence of races of Phytophthora clandestina (as determined by the development of root rot on differential cultivars), and the association of its occurrence with paddock variables. In all states, there was a weak but significant association between P. clandestina detected in soil samples and subsequent root rot susceptibility of differential cultivars grown in these soil samples. Phytophthora clandestina was found in 38% of the sampled sites, with a significantly lower prevalence in South Australia (27%). There were significant positive associations between P. clandestina detection and increased soil salinity (Western Australia), early growth stages of subterranean clover (Victoria), mature subterranean clover (South Australia), recently sown subterranean clover (South Australia), paddocks with higher subterranean clover content (Victoria), where herbicides were not applied (South Australia), irrigation (New South Wales and Victoria), cattle grazing (South Australia and Victoria), early sampling dates (Victoria and New South Wales), sampling shortly after the autumn break or first irrigation (Victoria), shorter soil storage time (Victoria) and farmer’s perception of root rot being present (Victoria and New South Wales). Only 29% of P. clandestina isolates could be classified under the 5 known races. Some of the unknown races were virulent on cv. Seaton Park LF (most resistant) and others were avirulent on cv. Woogenellup (most susceptible). Race 1 was significantly less prevalent in South Australia than Victoria and race 0 was significantly less prevalent in New South Wales than in South Australia and Western Australia. This study revealed extremely wide variation in the virulence of P. clandestina. The potential importance of the results on programs to breed for resistance to root rot are discussed. in South Australia.


2007 ◽  
Vol 47 (2) ◽  
pp. 226 ◽  
Author(s):  
P. G. H. Nichols ◽  
G. A. Sandral ◽  
B. S. Dear ◽  
C. T. de Koning ◽  
D. L. Lloyd ◽  
...  

Izmir is a hardseeded, early flowering, subterranean clover of var. subterraneum (Katz. et Morley) Zohary and Heller collected from Turkey and developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It is a more hardseeded replacement for Nungarin and best suited to well-drained, moderately acidic soils in areas with a growing season of less than 4.5 months. Izmir seed production and regeneration densities in 3-year pasture phases were similar to Nungarin in 21 trials across southern Australia, but markedly greater in years following a crop or no seed set. Over all measurements, Izmir produced 10% more winter herbage and 7% more spring herbage than Nungarin. Its greater hardseededness and good seed production, makes it better suited to cropping rotations than Nungarin. Softening of Izmir hard seeds occurs later in the summer–autumn period than Nungarin, giving it slightly greater protection from seed losses following false breaks to the season. Izmir is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. Izmir has been granted Plant Breeders Rights in Australia.


1985 ◽  
Vol 25 (2) ◽  
pp. 455 ◽  
Author(s):  
GR Stirling ◽  
MF Wachtel

In south-eastern South Australia root-knot nematode (Meloidogyne hapla) caused losses to potato crops in fields that were sown once every 5- 15 years and were used for grazing in the intervening years. Although seed used by some growers was infested with M. hapla, the nematode also survived between potato crops on subterranean clover (Trifolium subterraneum), the dominant pasture species, and capeweed (Cryptostemma calendula). Subterranean clover was the most abundant alternate host. Nematodes invaded clover seedlings that established following rain in April and produced eggs about 12 weeks later. A second generation was produced in late winter and spring, so that a relatively high root-knot nematode population was present when potatoes were planted. The population increased rapidly on potatoes and numbers capable of causing severe root damage were observed 10- 15 weeks after planting. The growing of non-host crops, or the use of herbicides or cultivation to eliminate subterranean clover in the winter prior to the potato crop, should be investigated. In a nematicide trial, ethylene dibromide at 70 and 110 kg/ha increased yields of potato cv. Pontiac by about 90%.


1985 ◽  
Vol 36 (1) ◽  
pp. 43 ◽  
Author(s):  
RC Rossiter ◽  
WJ Collins ◽  
Y Haynes

Single plants of subterranean clover (Trifolium subterraneum) were grown from seed of 13 commercial Seaton Park seed samples and of five pastures sown to Seaton Park at least 8 years previously. Most populations had several variants of Seaton Park, though the predominant genotype was that usually considered to be the Seaton Park strain - herein differentiated as Western Australian Seaton Park (W.A.S.Pk). The original Seaton Park - from the Royal Adelaide Golf Course in South Australia - differed slightly but clearly in several characters, including some seed isozyme patterns, from W.A.S.Pk. It was present in half of the populations, but at low frequencies (1-6% of the total). One genotype (strain S) comprised 20% or more of the populations from three commercial seed samples; it contained significant levels of the oestrogenic isoflavone formononetin. The origin of W.A.S.Pk remains unclear. The present commercial strain (cv. Seaton Park) is being re-built, based on W.A.S.Pk alone.


1955 ◽  
Vol 8 (3) ◽  
pp. 330 ◽  
Author(s):  
JN Black

An experiment is described in which the growth of subterranean clover (Trifolium subterraneum L.) in the early vegetative stage was measured over 52 consecutive weekly periods. To eliminate possible trends of growth rates with age, plants of comparable morphological stage were used for each period. The variety Bacchus Marsh was grown in pot culture in the open at the Waite Agricultural Research Institute, Adelaide, South Australia.


1970 ◽  
Vol 21 (5) ◽  
pp. 713 ◽  
Author(s):  
DA Shutt ◽  
RH Weston ◽  
JP Hogan

Studies have been made of the digestion and metabolism in Merino wethers of the isoflavones in subterranean clover (Trtfolium subterraneurn cv. Clare) and red clover (T. pratense). The dietary intake of isoflavones with both clovers was about 9 g per day. With the subterranean clover, the isoflavones were predominantly genistein and biochanin A, and slight teat length increases in the wethers ingesting this clover indicated a low level of oestrogenicity. With the red clover formononetin represented 60% of the isoflavone present and the wethers on this diet exhibited maximal teat length increases indicating a high level of oestrogenicity. Less than 1 % of the daily intake of the isoflavones was excreted as such in the faeces and urine; hence most of these compounds were metabolized or retained in the sheep. The dietary isoflavones were found to disappear rapidly from the rumen, and it was estimated by using marker techniques that the removal of these compounds from the stomach (rumen, reticulum, omasum, and abomasum) was virtually complete. Equol (7,4'-dihydroxyisoflavan), a metabolite of formononetin, was the predominant phyto-oestrogen in the digesta and excreta when red clover was given. The excretion of 3.9 g/day of this compound, mainly in urine, was equivalent to 70% of the intake of formononetin. It was calculated that about 86% of the equol produced in the rumen was absorbed from that organ; the mean residence time for equol in the rumen was estimated to be 1.7 hr. The isoflavones were present in blood plasma mainly in conjugated forms. Equol predominated with both clovers. The levels of equol were much lower with the subterranean clover than with the red clover diet; the concentrations of the conjugated form were respectively 13 and 300-440 �g/100 ml. Equol in the free form, although not detectable with the subterranean clover, was present at 4-10 �g/100 ml with red clover. The data were considered to be consistent with the conclusion that equol accounts for most of the phyto-oestrogenic activity in sheep fed on clovers containing high levels of formononetin.


2012 ◽  
Vol 63 (9) ◽  
pp. 902 ◽  
Author(s):  
D. M. Peck ◽  
N. Habili ◽  
R. M. Nair ◽  
J. W. Randles ◽  
C. T. de Koning ◽  
...  

In the mid 2000s subterranean clover (Trifolium subterraneum) seed producers in South Australia reported symptoms of a red-leaf disease in fields with reduced seed yields. The red-leaf symptoms resembled those caused by several clover-infecting viruses. A set of molecular diagnostic tools were developed for the following viruses which are known to infect subterranean clover: Alfalfa mosaic virus; Bean leafroll virus (BLRV); Beet western yellows virus; Bean yellow mosaic virus; Cucumber mosaic virus; Pea seed-borne mosaic virus; Soybean dwarf virus and Subterranean clover stunt virus. Surveys of subterranean clover seed production fields in 2008 in the south-east of South Australia and western Victoria identified Bean leafroll virus, Alfalfa mosaic virus and Cucumber mosaic virus as present, with BLRV the most widespread. Surveys of pasture seed production fields and pasture evaluation trials in 2009 confirmed that BLRV was widespread. This result will allow seed producers to determine whether control measures directed against BLRV will overcome their seed losses. Bluegreen aphid (Acyrthosiphon kondoi) was implicated as a potential vector of BLRV because it was observed to be colonising lucerne plants adjacent to subterranean clover seed production paddocks with BLRV, and in a glasshouse trial it transmitted BLRV from an infected lucerne plant to subterranean clover in a persistent manner.


2003 ◽  
Vol 54 (2) ◽  
pp. 203 ◽  
Author(s):  
B. S. Dear ◽  
G. A. Sandral ◽  
D. Spencer ◽  
M. R. I. Khan ◽  
T. J. V. Higgins

A bxn gene, coding for the nitilase enzyme that catalyses the detoxification of the herbicide bromoxynil, was inserted into subterranean clover (Trifolium subterraneum L. subsp. yanninicum). The agronomic characteristics of 3 transgenic lines (BXN 5, 7, 10) and their response to herbicides containing bromoxynil, were compared with that of the non-transgenic parent, cv. Gosse, in 1 glasshouse and 2 field experiments.The application of bromoxynil at 1.5 L/ha resulted in a 50% reduction in the spring herbage yield of the non-transgenic control but no reduction in BXN 5 and 7. The level of the phyto-oestrogens, genistein and biochanin A, in the leaf tissue were low in Gosse and the 2 transgenic lines, BXN 7 and 10, but the level of genistein increased significantly (P < 0.05) from 0.85% in Gosse to 1.43% dry weight in BXN 5, and biochanin A increased from 0.35% in Gosse to 0.73% in BXN 5. The application of the herbicides bromoxynil, bromoxynil+MCPA, and Jaguar (bromoxynil+diflufenican) at the cotyledon stage in a glasshouse study significantly reduced the leaf area of the non-transgenic Gosse, but did not reduce the leaf area of the 3 transgenic lines. When applied at the 4–5 leaf stage, the leaf area of Gosse was again reduced by all the herbicides, but only the bromoxynil+MCPA treatment reduced the leaf area of the transgenic lines relative to the control. The application of bromoxynil or Jaguar at the 4–5 leaf stage depressed the herbage yield of Gosse by about 62% compared with 0–24% in the 3 transgenic lines. In the field studies, BXN 5 and 10 had similar seed yields to Gosse in the absence of herbicide application, but the seed yield of BXN 7 was significantly less than the other 2 transgenic lines. The level of hard-seed in BXN 7 was also lower at 25% compared with 55–57% in the other transgenic lines and Gosse.These findings stress the need to carefully assess the agronomic qualities of transgenic lines prior to release as although tolerance to bromoxynil may be greatly increased by the bxn gene, other important agronomic characteristics, such as seed yield, hardseededness, and isoflavone content, may change as result of the gene or transformation process.


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