Showing papers in "Animal Production Science in 1970"

The effect of selenium on infertility in ewes grazing improved pastures

Abstract: 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

Resistance in cereals to the cyst nematode (Heterodera avenae) in Victoria.

Abstract: Two hundred and seventy cereal species and cultivars (wheat, barley, oats, rye, and Triticales), were field tested for resistance to the cereal cyst nematode (Heterodera avenae Woll.) in Victoria. Tests were made in the Wimmera District at Natimuk (1952-1954) and in the Mallee District at Walpeup (1953), and Sea Lake (1966-1969). Some species and cultivars were tested at all sites, but most were tested at one site only. All wheats tested were susceptible or very susceptible, and all Triticales were susceptible. Two barley cultivars, Morocco and Marocaine 079 were resistant, and two others were moderately resistant. The oat species, Avena sterilis and A. strigosa were resistant and fifteen cultivars of A. sativa were moderately resistant. Rye, CV. South Australian, possesses a high degree of resistance in contrast to European ryes.

Response to salinity in Glycine. 4. Salt concentration and the content of phosphorus, potassium, sodium and chloride in cultivars of G. wightii (G. javanica).

Abstract: Adaptability to salinity stress was related to the productivity of Glycine wightii (G. javanica) cultivars by the technique of comparing the multivariate characteristics of response for 22 accessions that are representative of the world centres of origin. Roots and tops responses were compared to clarify the metabolic relations between glycines, as salinity was increased from that required for normal growth and metabolism to levels almost causing death due to excess sodium chloride in the substrate. There was a range and pattern of response that suggested grouping among the glycines. One group in particular was more resistant to salinity stress than others. These glycines exemplified to a greater degree than others the tendency of all to exclude sodium and to a lesser extent chloride from the plant tops. These were also the more vigorously growing glycines with a higher potassium, phosphorus, and nitrogen content in both control and saline treatments. In them, vigour of growth and control of ion content were associated, and both these factors were important determinants of tolerance to salinity stress. Sodium appeared to be more toxic than chloride to plant growth. These aspects of growth and metabolism are discussed in relation to differences in ploidy between the groups of glycines. The technique used shed further light on the important agricultural problem of combining adaptability and high productivity.

Resistance to common root rot (Cochliobolus sativas) In wheat in Queensland.

Abstract: The field resistance to common root rot (Cochliobolus sativus) of wheat lines, graded for their reaction to this disease in Canada, was determined under Queensland conditions. Several Australian varieties were also examined. Lines considered resistant and susceptible in Canada behaved in a similar fashion under Queensland conditions, while Australian varieties were generally intermediate. Discolouration of the sub-crown internode was the commonest symptom of the disease and was associated generally with a decrease in individual plant yield and in the number of heads on each plant. Discolouration of the sub-crown internode associated with Pyrenochaeta sp. in one experiment gave a varietal reaction pattern similar to that obtained with C. sativus at other sites. There appears little relationship between varietal reaction to common root rot and that previous1 reported to crown rot (Gibberella zeae).

Skeleton weed (Chondrilla juncea) in the Victorian Mallee. 2. Effect of legumes on soil fertility, subsequent wheat crop and weed population

Abstract: Following two to three years of competition between lucerne, annual medics, or field peas with skeleton weed at six sites in the Mallee, Victoria, a wheat crop was grown on fallow at each site between 1966 and 1968 to determine the effect on the weed populations and to measure the relative ability of the legumes to improve the nitrogen content of the soil. Skeleton weed populations declined throughout both the fallow and cropping periods on all treatments, and the possible mechanisms involved are discussed. All legumes increased the nitrogen status of the soil at the different sites, which led to higher wheat yield and grain protein content. There was limited response to applied nitrogen fertilizer, except on the volunteer pasture treatments. Lucerne and the annual medics were similar in their effects on soil nitrogen. However, moisture conservation during the fallow period was more effective following lucerne in some years, owing to the lower skeleton weed populations, and resulted in much higher grain yields in the drought year of 1967.

The effect of varieties, nitrogen and stubble treatments on successive cycles of grain and forage sorghums in the Ord River valley.

Abstract: Two exploratory experiments with re-cycled (ratooned) grain sorghums (hybrid Texas R.S. 610 and standard variety Alpha) and forage sorghums (hybrid Sudax and standard variety Sugardrip) were carried out at Kimberley Research Station to provide data for the initial assessment of sorghum production possibilities in the Ord River area. Re-cycling of sorghum led to progressive reduction in grain and dry matter yields. Grain yield reduction was greater when stubble was cut at the header height (approximately 40 inches) than when it was cut at 6 to 8 inches above ground level and removed. Grain and dry matter yields were higher for Texas R.S. 610 than for Alpha, while dry matter yield of Sudax was also higher than that of Sugardrip. Nitrogen application at 50 lb N an acre and 100 lb N an acre increased grain yields of Texas R.S. 610 and Alpha. It also increased dry matter yields of these two varieties and of Sugardrip, while dry matter yield of Sudax did not respond above the 50 lb N an acre rate of application. Relative, but not absolute, reduction of grain and dry matter yields in successive cycles was diminished by nitrogen application.

Evaluation of rapid tests for assessing nitrogen availability in wheat soils. 2. Effect of factors associated with field sampling, sample treatment and laboratory analysis

Abstract: An evaluation of biological and chemical tests of potentially available soil nitrogen has been made through a study of factors associated with field sampling, sample treatment, and laboratory analysis Variations in time of sampling, fineness of grinding, and the conditions and period of storage of air-dry samples were generally shown to affect the values obtained by both biological and chemical methods, but not the degree of correlation with plant uptake of nitrogen. These findings, together with information gained on method precision and spatial variability and analytical considerations, led to the choice of organic carbon as the best of the methods tested.

Effect of flock size and grazing management on sheep production.

Abstract: No effect of flock size on wool production was detected over twelve months in flocks of 3, 9, 27, or 135 sheep. Each flock was composed of equal numbers of Merino, Comeback, and Border Leicester X Merino weaners stocked at nine per acre on Phalaris tuberosa-Trifolium subterraneum pastures at Canberra. Liveweight gains and fleece weights of the sheep were similar whether they were set-stocked, rotated around three subdivisions of a rotationally grazed pasture, or in three flocks rotated around three subdivisions of a pasture, which was thus continuously grazed. These results indicate that rotation per se had no important effect on animal production. Merinos in mixed flocks, with Comebacks and Border Leicester X Merinos, gained significantly less weight during autumn and winter and significantly more weight during spring than Merinos in pure flocks at the same stocking rate. There were no differences between pure and mixed flocks in either of the other breeds.