bluuebunny/crossref_metadata_2025 huggingface dataset:
Some aspects of soil shrinkage and the effect of cracking upon water entry into the soil.
Authors: Stirk GB
Published: November 2004

The shrinkage of natural soil aggregates that accompanies water withdrawal has been examined. Four main stages operate: (1) structural shrinkage, (2) normal shrinkage, (3) residual shrinkage, (4) no shrinkage: The pF ranges over which these stages operate and the fraction that they constitute of the total shrinkage has been measured for a range of soils. The influence of structure and texture upon shrinkage was assessed. These affect both the shrinkage phase and the range over which it operates. Structural development affects shrinkage markedly, giving a very different shrinkage pattern from that found for puddled soil or remoulded soil blocks. The difference in porosity between a natural aggregate and a puddled block of the same soil corresponding to a definite pF value is suggested, therefore, as a means of assessing the degree of structural development in the soil. It provides a suitable index for assessing the rate of structure improvement under various ameliorative treatments. The influence of cracking in increasing the rate of water entry into fine textured soils is discussed. In the particular cases of irrigated soils, where soil water contents are maintained at relatively high levels (above wilting point), it seems that cracking may not have progressed sufficiently to compensate for the low inherent permeability of such soils. Cultivation of the surface soil to form a mulch before irrigation tends to eliminate any contribution to conduction by the smaller cracks which are present at higher soil water contents. Large increases in permeability, due to the presence of gross soil cracks, are attained only when water contents are reduced to levels which are not practicable in continuous irrigation culture.
The effect of the presence of the ram on the ovarian activity of the ewe.
Authors: Schinckel PG
Published: November 2004

Observations were made on the effect of the presence of the ram when introduced to Merino ewes in the transition from the "non-breeding" to the "breeding" season in the Roseworthy environment. These observations showed that the primary effect was to stimulate ovulation without oestrus ("silent heat") in the majority of those ewes which had not already commenced cyclic breeding activity. This effect occurred within 6 days of joining the rams with the ewes. It is concluded that this mechanism explains the "lag and peak" incidence of oestrus previously observed under these conditions (Underwood, Shier, and Davenport 1944; Thompson and Schinckel 1952; Schinckel 1954).
Sampling of fleeces for yield, staple length, and crimps per inch measurement.
Authors: Lockart LW
Published: November 2004

Samples of wool from 26 Merino sheep at Trangie Agricultural Experiment Station were taken from 27 sites over the right side and a composite sample from the left side. Gradients in staple length, crimps per inch, yield, and per cent. vegetable matter are demonstrated. The correlation between yield of 25-30 g samples and yield of a composite sample from the opposite side of the fleece is at a maximum of approximately 0.92 along the shoulder-midside-hip area. The correlations between yields of samples of 5, 10, 20, 40, and 75 g from the midside and composite samples from the opposite side are 0.73, 0.86, 0.91, 0.94, and 0.94 respectively. Therefore there does not appear to be any advantage in taking samples larger than 40 g from the midside. When yield is calculated so as to remove the effect of vegetable matter, correlations between positional samples and composite sample are mostly slightly higher, but the general findings are not altered. For staple length and crimps per inch the correlations between site value and mean sheep value are at a maximum along the shoulder-midside-hip region, similarly to yield. Mean values for crimps per inch, staple length, yield, and per cent. vegetable matter for left and right sides do not differ appreciably. For these characters correlations between values for individual samples from the same position on the two sides are of the order of 0.9.
Pasture studies on the coastal lowlands of subtropical Queensland. II. The interralation of legumes, rhizobium, and calcium.
Authors: Bryan WW , Andrew CS
Published: November 2004

The soils of the coastal lowlands of southern Queensland are deficient in many nutrients, including phosphorus, calcium, and nitrogen. Initial attempts to grow clovers on these soils failed because available strains of Rhizobium were not effective and the plants suffered acutely. When useful strains of bacteria were obtained this lack of nitrogen was largely overcome. Until effective strains of Rhizobium are associated with legume hosts, the legumes do not, under local conditions, respond normally to nutrients. In particular, responses to calcium may be quite abnormal. The response of a legume to calcium can be used in some cases as a measure of the effectiveness of the associated Rhizobium on these soils. Effective strains of Rhizobium were successfully applied to existing stands of white clover on three soil types both in the form of inoculated soil and in aqueous suspension.
Characteristics of a bunch spear grass (Heteropogon contortus (L). BEAUV.) pasture grazed by cattle in subtropical Queensland.
Authors: Shaw NH , Bisset WJ
Published: November 2004

A study of a native pasture of bunch spear grass (HHeteropogon contortus (L.) Beauv.) grazed by beef cattle in subtropical Queensland is reported. The yield and botanical and chemical composition under continuous grazing were recorded over 4 years. Spear grass contributed up to 90 per cent. of the yield of dry matter which ranged from 1 to 2 tons/acre. Approximately 60 per cent. of the total yield was produced between January and April, and there was almost complete absence of growth in the cooler months even when rain occurred. The nutritive value of the forage was low for much of the year, with the crude protein content falling to 2-3 per cent. in the winter. The degree of consumption of forage by stock was low, particularly in the winter, and it was apparent that under the existing form of management the stock had little effect on the pasture. It is concluded that there is little prospect of increasing beef production per acre by grazing management of the native pasture, and that, as the major drawbacks to production stein from the pasture species rather than the climate in which they grow, the logical approach is to replace them by sown grasses and legumes. This involves studies of introduced species and, as many of the soils are of low fertility, attention to plant nutrient deficiencies. Work along these lines is now in progress.
The hair follicle and apocrine gland populations of Zebu (Bos indicus L.) and Shorthorn (B. taurus L.) cattle skin.
Authors: Dowling DF
Published: November 2004

Skin samples taken with a trephine of known size from Shorthorn (Bos taurus L.) and Zebu (B. indicus L.) cattle were used to determine the density of hair follicles and apocrine glands in the skin. The repeatability of the measurement of density on the same animal was found to lie between 78 and 90 per cent. The expansion of the skin as the animal grows, and the manner in which the plane of nutrition can modify growth and so the extent of expansion, has a predominating effect on the hair follicle and apocrine gland density. There is a significant difference between ages, but for each breed the regression coefficients of log follicle number on log heart girth within age groups are not significantly different. The mean number of hair follicles per sq. cm in Zebus was 1698, in Zebu crosses 1321, and in Shorthorns on a low plane of nutrition 1064. In Shorthorns on a high plane the number was 764. All differences were statistically significant.
Effect of soil structure on wheat germination in a red-brown earth
Authors: McIntyre DS
Published: November 2004

Physical properties of soil have been measured on two experimental plots which showed high compaction and poor germination of wheat under very wet conditions. The plot treatments were a two-course and a four-course rotation, and formed part of a permanent rotation trial at the Waite Institute. Similar physical properties were measured for thick crusts formed on these cultivated soils. Under the wet conditions pore space available for air was low in both plots, and within the crust itself was almost zero. Significant differences were found in bulk density and water-stable aggregation between treatments. Waterstable aggregation was very low under both treatments compared with that in virgin soil. All physical measurements point to an oxygen deficiency for a period of 2-3 weeks, and this could account for the poor germination and poor early growth, particularly in the two-course rotation plots. The bad structure conditions leading to this are probably due to pulverizing by implements and dispersion over the years by heavy rain, rather than to decrease in organic matter.
Photoperiodicity in cattle. I. Seasonal changes in coat character and their importance in heat regulation
Authors: Yeates NTM
Published: November 2004

The seasonal changes in coat character of a control group of four young Poll Shorthorn cattle have been studied and compared with those of a similar group in which the daily photoperiod was altered to simulate the synchronous duration of daily lighting of the opposite (northern) hemisphere. Heat tolerance tests were conducted periodically as the animals assumed different coat types. The results show that the full range of coat changes which characterize well-nourished cattle of the type used in this experiment may, irrespective of seasonal temperature, be reversed by artificially reversing the seasonal trend of daylight duration. This is presumptive evidence that the natural light environment is a major controlling factor in the normal pattern of seasonal coat change which cattle of European origin exhibit. Cattle with sleek, summer-type coats have shown decisive heat tolerance superiority over those with deep, winter-type coats under the conditions of this experiment. Clipping tests indicate that it is the heavy coat itself which lowers heat tolerance, not a particular internal condition (of metabolism, for example) with which heavy-coatedness might be associated.
The influence of seed size and depth of sowing on pre-emergence and early vegetative growth of subterranean clover (Trifolium subterraneum L.)
Authors: Black JN
Published: November 2004

Changes in the pre-emergence distribution of dry matter in subterranean clover (Trifolium subterraneum L.) variety Bacchus Marsh were followed at 21°C, using three sizes of seed and three depths of sowing, ½, 1¼, and 2 in. Decreasing seed size and increasing depth of sowing both reduce the weight of the cotyledons a t emergence. Seed of the three sizes were sown a t three depths in pot culture a t staggered intervals so that emergence was simultaneous. Dry weight in the early vegetative stage was proportional to seed size, and total leaf area and leaf numbers showed similar trends. Plants of each seed size grew at the same relative rate. No effect of depth of sowing could be detected, and this was shown to be due to the cotyledon area a t emergence being constant for any given seed size, regardless of varying depth of sowing and hence of cotyledon weight. It was concluded that seed size in a plant having epigeal germination and without endosperm is of importance: firstly, in limiting the maximum hypocotyl elongation and hence depth of sowing, and secondly, in determining cotyledon area. Cotyledon area in turn influences seedling growth, which is not affected by cotyledon weight. Once emergence has taken place, cotyledonary reserves are of no further significance in the growth of the plants.
Nitrogen studies on black soils form the Darling Downs, Queensland. II. The nitrifying activity of subsurface horizons
Authors: Martin AE , Cox JE
Published: November 2004

Rates of nitrification of a black clay soil were studied with the percolation technique, using samples from various depths down to 3 ft. There was a marked decrease in nitrification rate with increasing depth, the successive curves showing longer lag periods. Deep samples, which contain more chloride and have a higher pH value than those from the surface, accumulated large quantities of nitrite. Chloride, added to the percolators in concentrations equal to those found in the profile, had no marked effect on nitrite accumulation but slightly reduced the rate of nitrate production. The percolation of surface samples with ammonium sulphate solutions with the pH increased by alkali additions resulted in marked nitrite accumulation comparable with that found in deeper layers in presence of ammonium sulphate only. Continued repercolation at high pH values gave evidence of adaptation of the soil organisms to alkaline conditions; the percolate pH at which maximal nitrite accumulation was recorded rose with successive treatments. It was concluded that the decrease in nitrifying capacity with depth is related to reduction in numbers of active organisms and to the partially selective effect of high pH on the oxidation of nitrite.
Toxaphene-resistant cattle ticks (Boophilus microplus (Canestrini)) occurring in Queensland
Authors: Norris KR , Stone BF
Published: November 2004

Cattle ticks on four herds in southern Queensland survived dipping in a vat charged with 0.5 per cent. w/v toxaphene, which nevertheless disinfested a fifth herd. Protective periods afforded by toxaphene against attachment of resistant larvae were much shorter than against susceptible strains. Laboratory concentration-response tests on a culture of the toxaphene-resistant ticks indicated that the median lethal concentration of toxaphene for engorged females was 19 times higher than that of a reference strain, and t h at f o r the larvae was also significantly higher. The toxaphene-resistant ticks were not affected when cows were sprayed with 0.05 per cent. w/v gamma-BHC. This was consistent with an earlier history of BHC resistance in the ticks on these herds. Spraying trials indicated no marked arsenic resistance in the toxaphene-resistant ticks. The mortality of the toxaphene-resistant ticks on cattle sprayed with 0.5 per cent. W/V pp'-DDT, and the protective period against larval reinfestation, were as high as usually observed in other tick populations. A very high kill resulted from spraying the toxaphene-resistant ticks with 0.05 per cent. w/v diazinon. Subcutaneous injections of peanut oil solutions of lindane, dieldrin, and aldrin at the rate of 25 mg toxicant/kg host body weight were without effect on toxaphene-resistant ticks.
Studies in citrus nutrition i. Leaf growth and composition
Authors: Williams RF , Gates CT
Published: November 2004

Vegetative shoots from the spring flush of an experimental citrus grove tagged and sampled on three occasions at intervals of 6 months. The effects of four cultural treatments, four levels of nitrogen supply, four combinations of stock and scion, and of time on leaf area and dry weight, and on relative and absolute contents of water, nitrogen, and phosphorus are presented and discussed. While nitrogen nutrition is still the dominant factor, the evidence strongly suggests that phosphorus nutrition has become important as a determinant of treatment effects within the experimental grove. The possible relevance of soil temperature and soil organic matter for some of the cultural treatment effects is discussed.
Investigations on brown rot of apricots caused by Sclerotinia fructicola (Wint.) Rehm. I. The occurrence of latent infection in fruit
Authors: Wade GC
Published: November 2004

Evidence is presented that infection of apricot fruit with Sclerotinia fructicola may occur early in the fruit's development but remain latent until ripening commences. Evidence from culturing from green fruit is supported by the results of spraying experiments with fungicides and by inoculation experiments. Latent infection is confined to the epidermis and is not associated with any particular position on the fruit surface. Histological studies indicate that infection takes place through the stomata. It is tentatively suggested that an inhibitory substance is present in green fruit, and maintains infections in a latent condition. The presence of a substance inhibitory towards a species of Histoplasma is demonstrated. This substance begins to disappear as ripening commences.
Microbial antagonism in the rhizosphere as a factor in the failure of inoculation of subterranean clover
Authors: Hely FW , Bergersen FJ , Brockwell J
Published: November 2004

In an investigation into the cause of poor nodulation of subterranean clover on a yellow podzolic soil the following results were obtained: (1) Failure of seed inoculation was due to microbiological antagonism which prevented normal colonization of the rhizosphere by the bacteria in the applied inoculum. (2) The antagonism was shown to be confined to the clover rhizosphere. (3) Greater rhizosphere populations were obtained by the use of increased rates of inoculation or with normal rates on the sites of log fires. This latter effect was attributed to the presence of charcoal. (4) The technique used for the determination of numbers of nodule bacteria in the clover rhizosphere was found to give an early and reliable evaluation of the success of inoculation.
Ruminal flora studies. VIII. The influence of rate and method of feeding a ration upon its digestibility, upon ruminal function, and upon the ruminal population
Authors: Moir RJ , Somers M
Published: November 2004

A single ration made up of commercial sheep cubes (20 per cent. protein) together with oaten and lucerne chaff was fed to five sheep in five different ways. A Latin square design was used. Measurements were made on the ruminal population, the metabolism within the rumen, and the overall nitrogen balance and dry matter digestibility. Each of the different treatments resulted in a distinctive pattern in the ruminal population, pH, ammonia nitrogen, and volatile fatty acid levels. There were significant differences in dry matter digestibility and nitrogen retention. The daily ration given as a single feed gave the lowest dry matter digestibility and nitrogen retention. It also caused the greatest fall in pH values and bacterial counts, and the lowest protozoal counts. The highest ruminal ammonia nitrogen levels were also associated with this treatment. The best performance was obtained by feeding the concentrate in the morning and roughage in the afternoon, or feeding the whole ration in four equal portions at 2-hr intervals. The other two treatments – half ration morning and afternoon, or chaff in the morning and concentrates in the afternoon – gave intermediate results. Some implications of the various data are discussed, and the strong influence of feeding pattern is stressed.
Effects of inbreeding on four families of Peppin Merinos
Authors: Doney JM
Published: November 2004

The influence of inbreeding on several fleece and body characters in a strain of Australian Merino sheep is reported. The four families from which data were taken were derived from a single strain of Peppin Merinos. Inbreeding without selection has been carried on since the foundation of the families between 1939 and 1944.
Inbreeding is responsible for a reduction in body size, fertility, greasy and clean fleece weight, and wrinkle score, but has relatively little influence on the fleece components (yield, staple length, fibre diameter, and density of fibre population). It follows that the reduction in fleece weight is a direct consequence of a decrease in total fibre number. Since the reduction in fibre number is likely to be a correlated effect of low pre-natal and early post-natal growth rates, it is suggested that the inbreeding has had no genetic effect on the several independent systems involved in adult wool production but has affected only those associated with fitness and vigour. The depression due to inbreeding therefore may not be caused by specific gene fixation but by increased homozygosity per se.
Expansion and distribution of the pedigree Jersey breed in Australia
Authors: Barker JSF
Published: November 2004

(i) The expansion of the pedigree Jersey breed in Australia has been due to extension of the geographical range, increase in number of herds, and increase in average herd size. The breed is at present doubling its numbers about every 10 years. (ii) Large fluctuations in population size from year to year have been observed. These could give rise to considerable random drift of gene frequencies. (iii) The approximate culling rate of pedigree Jersey females is calculated as 10-15 per cent. per annum. (iv) The extent of selective registration of bulls could be increased. Approximate calculations show that the number of bulls registered could be halved and the pedigree bull requirements of the breed still satisfied.
The breed structure and genetic analysis of the pedigree cattle breeds in Australia
Authors: Barker JSF
Published: November 2004

(i) The breed structure and genetic history of the pedigree Jersey breed in Australia are analysed by pedigree sampling methods. (ii) The breed structure may be divided into four levels, with imported animals at the top determining the genetic make-up of the breed. Animals imported since 1900 have made a genetic contribution to the breed in 1950 of 61.8 per cent. At least two substructures exist within the breed, based respectively on the major herds in Queensland and those in the rest of Australia. (iii) The genetic contribution to the breed of the most important of the herds is only 7.0 per cent. (iv) Determination of the percentage direct relationship of important animals in five sample years shows that no one animal has made a major contribution to the genotype of the breed. (v) The degree of inbreeding (base year 1900) is calculated. The total inbreeding in 1950 (4.19 per cent.) comprises 1.31 per cent. current inbreeding, 0.51 per cent. long-term inbreeding, and 2.37 per cent. strain inbreeding. The index of subdivision calculated from the non-current and long-term inbreeding is 5.65, indicating that the breed is subdivided into strains. (vi) The effective generation length for each of the pedigree breeds – Jersey, Australian Illawarra Shorthorn, Friesian, Ayrshire, and Guernsey – in Australia is 5 years. Most bulls are used when they are 1-3 years old, and are then lost to the pedigree industry. It is shown that the bull requirements of the above breeds could be met by the progeny of performance-recorded animals. Whether this would increase the rate of genetic improvement is discussed briefly. (vii) Genetic improvement in the Jersey breed could best be achieved by: ( a ) stopping further importation; ( b ) closing the breed in each environment and concentrating selection within these regions to develop strains adapted to each particular environment; ( c ) selecting on production records rather than using genetically unknown sires and dams, particularly in the major breeders' herds.
Competition between skeleton weed (Chondrila juncea L) and cereals in relation to nitrogen supply
Authors: Myers LF , Lipsett J
Published: November 2004

The effect of skeleton weed competition on the yield of wheat and oats was investigated in seasons when rainfall was plentiful. Nitrogen was found to be the major factor limiting crop yields. In soils with comparable nitrogen-supplying powers, skeleton weed density governed the crop's response to applied nitrogen. Competition between skeleton weed and crop was severe at low nitrogen levels, but minor at the high nitrogen levels achieved either by nitrogen application, or when the crop followed a legume-rich pasture. Competition had its effect early in the crop's growth. Temporary removal of competition, by spraying with plant growth regulating substances (JICPA) at different times, was used to determine when competition was critical, and measure its effects. Skeleton weed reduced nitrogen supply early in the crop's growth, and so depressed yield. An application of 1 lb MCPA per acre in the fallow 54 days before sowing, or 10 days after crop emergence, increased the yield of oats from 710 to 1350 lb grain per acre: a response equal to that from 32 lb nitrogen per acre applied at planting in the same experiment. In each case, the response to spraying at the different times was analogous to the effect of a nitrogen application at these times. Early spraying gave responses in yield; later spraying gave responses in grain nitrogen. The results provide a new estimate of the reduction in crop yield due to skeleton weed.
Fertility investigations on the black earth wheatlands of the Darling Downs, Queensland. I. Moisture accumulation under short fallow
Authors: Waring SA , Fox WE , Teakle LJH
Published: November 2004

The accumulation of soil moisture during the period of summer fallow between successive winter crops of wheat has been examined for a number of localities on the Darling Downs, and for the seasons 1951-1954. The moisture gain to a depth of 4 ft between the harvest of one crop and the planting of the succeeding crop ranged from – 0.3 to 5.0 in., with an average of 2.2 in. representing 17 per cent. of the rainfall. Available moisture at planting averaged 4.8 in., the excess of 2.6 in. over fallow gain being due to the available moisture already in the soil at the preceding harvest. In this locality, therefore, moisture accumulation commonly occurs prior to harvest, owing to rainfall in excess of crop requirements at this period. The average values for available moisture at planting mere well below the capacity of these soils for storage to 4 ft. Values following long fallow averaged 6.5 in., and were as high as 9.9 in. in one instance. Correlations have been sought between fallow moisture gain and available moisture at planting, and the associated soil and climatic factors. The more important findings were : (1) Total rainfall during the fallowing period was not correlated with fallow moisture gain. (2) Fallow moisture gain and available moisture at planting were correlated with March-April rain. (3) Fallow moisture gain was correlated negatively with available moisture at the preceding harvest and positively with available moisture at planting. (4) The clay content of the soil and depth of surface mulch were not significantly related to fallow moisture gain nor to available moisture at planting. (5) No significant difference in moisture accumulation was observed between sites stubble-mulched and those stubble-burnt. Explanations in terms of climatic and soil characteristics are offered for the results obtained. Features considered important are the characteristics of the rainfall and the high-evaporation conditions, the low rate of moisture penetration in wet soil, and the high moisture-holding capacity of the surface soil layers.
Moisture relations of hay species
Authors: Shepherd W
Published: November 2004

Moisture relations of four species used for making hay—white clover (Trifolium repens L.), subterranean clover (Trifolium subterraneum L.), lucerne (Medicago sativa L.), and perennial ryegrass (Lolium perenne L.)—have been investigated. Shapes and positions of equilibrium moisture content-relative humidity curves differed between species; and in general, moisture contents were lower for fast-cured than for slow-cured material and lower for over-mature than for less mature material. Sorption hysteresis effects were observed. Under the experimental conditions employed, equilibrium moisture contents were lower for material subjected to conditioning atmospheres immediately after mowing than for material cured prior to conditioning. Variations in the shape and position of equilibrium curves were frequently in accordance with known variations in chemical composition.
The role of carbohydrate reserves in regeneration of plants. I. Carbohydrate changes in subterranean clover following defoliation
Authors: May LH , Davidson JL
Published: November 2004

A study was made of changes in the total available carbohydrate of subterranean clover sown at different densities. Swards were subjected to a single defoliation at various dates, and sampled for carbohydrate analysis at intervals after defoliation. The carbohydrate content was much higher, and the decrease after defoliation much greater, in the tops than in the roots. The rate of decline decreased with increasing time after defoliation and the decline was followed by a period of recovery. No consistent effect of plant density was apparent. These results conform to those of previously published experiments for other pasture grasses. It is postulated from other data presented that the percentage decrease in non-structural carbohydrate after defoliation follows largely its use as respiratory substrate, and, to a lesser extent, as material translocated to the roots and in syntheses at new growing points. The significance of these changes is discussed, and it is concluded that further physiological research is required to justify the widely held belief in the importance of "reserve" substances to regrowth.
The influence of selection and plane of nutrition on the components of fleece weight in Merino sheep
Authors: Dun RB
Published: November 2004

The components of clean fleece weight were examined in five experimental flocks of medium-wool Peppin Merinos. Four single-character selection groups – clean fleece weight plus, clean fleece weight minus, crimps per inch plus, and crimps per inch minus – were examined by measuring fleece production in 18-month-old ewe progeny. Measurements were also made on progeny from the "nucleus" flock, which was selected for clean fleece weight with subsidiary selection for crimps per inch and against fold score. Data were collected in 1952 and 1954. The 1954 figures were obtained from a nutrition experiment in which sheep mere grown from weaning to 18 months on a high and on a low plane of nutrition. The mean measurements of the components of clean fleece weight (W) were compared between flocks using the "percentage deviation" technique. Four comparisons were made: (1) Nucleus/Fleece minus; (2) Fleece plus/Fleece minus; (3) Crimps minus/Crimps plus; (4) high nutritional plane/low nutritional plane. In comparisons (1) , (2), and (3), difference in weight of wool per unit area of skin (w) accounted for nearly all the difference in W. Body weight (S) made a small contribution while difference in fold score (R) was negligible. Fibre density (N) accounted for +86 per cent., and fibre cross-sectional area (A) for –28 per cent., of the difference in W in comparison (1). In comparison (2) the figures were N +47 per cent., A +21 per cent., while the figures for comparison (3) were N –26 per cent., A +121 per cent. The increase in fleece weight was invariably accompanied by a decrease in crimps per inch. In all three comparisons primary density (P) was the major cause of change in N. Fibre length (L) made a uniform contribution of approximately +15 per cent. in the three comparisons.The relative importance of the components of fleece weight was similar at both high and low levels of nutrition.The effect of a high level of nutrition was to produce large increases in A, L, and S. The increase in S was compensated by an equal decrease in P. The increase in fibre diameter was not associated with any change in crimps per inch.
In vitro studies on the effect of pH and of glucose on ammonia accumulation in the rumen of sheep
Authors: Ries PJ , Reid RL
Published: November 2004

The effect of pH and of glucose on ammonia accumulation in rumen liquor, obtained from sheep rumen contents, was studied during 4-hr in vitro incubations. Control of pH over the range 4.5-7.3 was effected with sodium phosphate-citric acid buffer. Casein hydrolysate was added as a substrate for ammonia production. There was an optimum pH for ammonia accumulation which varied between 6.0 and 6 . 7 on different diets, and which appeared to be correlated with the range of pH normally encountered in the rumen on each diet. Ammonia accumulation fell rapidly on the acid side of the optimum pH and usually less rapidly on the alkaline side. This effect of pH is most probably due to an effect on ammonia production, i.e. an effect on deamination of amino acids. Glucose reduced ammonia accumulation to an extent greater than could be accounted for by the fall in pH due to the fermentation of glucose; protein nitrogen levels in the reaction mixture were significantly increased. It was concluded that the effect of glucose was due largely to a stimulation of ammonia utilization for synthesis of microbial protein and not to an inhibition of ammonia production.
Wool follicle development in New Zealand Romney and N-type sheep. 3. Diameters of follicles and fibres
Authors: Stephenson SK
Published: November 2004

The diameters of the primary and secondary follicles hare been measured in N type and New Zealand Romney foetuses. It is shown that the primary effect of the N gene is on the primary follicle papilla and fibre size, not on overall follicle size A secondary pleiotropic effect is on the primary follicles, which Increase in diameter as a result of growing large fibres There do not appear to be any other effects of the dominant N gene up to 126 days after conception, either on the follicle population or on the growth of the foetus.
Sweat glands in cattle: Histology : Morphology, and Evolutionary trends
Authors: Nay T
Published: November 2004

Basic morphological types of sweat glands in various groups of cattle are described, the volumes of glands measured, and differences in volume between and within groups demonstrated. Two distinct trends in the evolution of the sweat gland in cattle are discussed.
Insecticides for the control of the lucerne flea, Sminthurus viridis (L.), and the red-legged earth mite, Halotydeus destructor (Tuck), and their effects of population numbers
Authors: Wallace MMH
Published: November 2004

Experiments are described which demonstrate effective insecticidal treatments for the control of the lucerne flea, Sminthurus viridis (L.), and the red-legged earth mite, Halotydeus destructor (Tuck.). As dual purpose insecticides, malathion/DDT, malathioli/lindane, and endrin all gave excellent results. The lower cost and lower mammalian toxicity of malathion/ DDT favour this mixture, which is now recommended for field use. Also effective against the lucerne flea were dieldrin, chlorthion, and "Diazinon". Lindane and "Dilan" gave good controlof the red-legged earth mite, but DDT was superior to both. None of the materials used for the control of the lucerne flea had an effective residual action, so that careful attention to the time of application of the insecticides was essential for optimum results. Treatment within 3-5 weeks of the rains which initiate hatching of the oversummering eggs is recommended. Eradication was not achieved by any of the treatments. The subsequent effect of insecticidal treatment on the population density of both pests is discussed. The numerical changes which followed the application of insecticides suggest that density-governing factors play an important part in the regulation of the numbers of both species.
The influence of earthworms on soil fertility. I. Earthworm populations found in agricultural land near Adelaide
Authors: Barley KP
Published: November 2004

The most common earthworms in the agricultural land examined were the introduced lumbricids Eisenia rosea (Sav.) and Allolobophora caliginosa (Sav.). Pastures established for 6 or more years carried an average of 80 g of worns per 1000 g annual production of dry herbage. Very few worms were found in soil which had been cropped on a tm-o course rotation for 30 years. Where land was cropped on a four course rotation of 2 years' ley/fallow/wheat, the weight of worms fluctuated during the rotation. After the fallow and crop years the weight was only a quarter of that found on permanent pasture. but at the end of the ley the weight almost equalled that on the permanent pasture. The earthworms mere active for about 24 weeks each year. In winter, when the worms were feeding, most were in the top 15 cm of soil. As the soil dried out in spring the worms tunnelled more deeply and aestivated at depths of 15-60 cm.
Studies on fluorosis of sheep. III. The toxicity of water-borne fluoride for the grazing sheep throughout its life
Authors: Peirce AW
Published: November 2004

Three experimental groups of lambs were given water containing the same three different levels of fluorine, added as sodium fluoride, that their mothers had received during pregnancy and lactation. Group A (control), containing 21 wethers and 11 ewes, received water containing about 0 . 3 p.p.m. F, group B (17 wethers) received water containing 10 p.p.m. F, and group C (20 wethers and 10 ewes) received water containing 20 p.p.m.F. The ewes were mated in each of the last 6 years, and the experiment was terminated when the animals reached 7 years of age. During the winter months little water was drunk. In the summer months the daily intake of water by groups B and C rose to 41, equivalent to 40 and 80 mg F, for the two groups respectively. Their overall mean daily intake for the whole experiment was 14 and 27 mg F respectively. Water containing 10 p.p.m. F appeared to have no adverse effects on the health of the sheep, but decreased wool production and induced characteristic changes in the teeth. Water containing 20 p.p.m. F affected health and wool production, and induced more severe signs of fluorosis on the teeth. Neither concentration affected reproductive performance. Increases up to threefold were observed in the fluoride content of the bones and teeth. The implications of the findings are discussed, particularly in relation to flock management in Queensland.
Earthworms and soil fertility. IV. The influence of earthworms on the physical properties of a red-brown earth
Authors: Barley KP
Published: November 2004

On a permanent pasture near Adelaide, South Australia, the amount of soil which earthworms bring to the surface each year is equivalent to a layer 0.2 mm in thickness. Although this rate of transport is too small to counteract compaction caused by livestock, it is sufficient to bury stones and other particles too large for the worms to ingest to a depth of several centimetres within a period of a few hundred years. Worm tunnels which are fresh enough to be recognized are too wide to conduct water at the tensions commonly encountered during infiltration. Even if all the tunnels are filled with air, they do not occupy enough space within the B horizon of a red-brown earth to have much influence on the rate of gaseous diffusion: at a depth of 50 cm the total cross-sectional area of the tunnels is only 0.7 sq. cm per sq. metre of soil. The space occupied by the tunnels within the A horizon is difficult to determine because of the abundance of plant roots, which are probably far more important than worms in modifying pore size distribution.
Studies of the effects of the gene N on body growth and fleece development of the New Zealand Romney. I. The body growth of the N type lamb
Authors: Cockrem F , Rae AL
Published: November 2004

A study has been made of the pleiotropic effects of the gene N on the body growth and the carcass of the Sew Zealand Romney lamb. Measurements of body weight and height at withers were taken from birth to about 5 months of age for lambs born in 1952 and 1953 from matings of N/+ x +/+, N/N x N/N, N/N x N/+, and N/+ x N/+ parents. In 1952, +/+ lambs grew faster than N/+ or N/N lambs and this was shown in the greater body weight of the +/+ lambs at 30 days of age. The differences in weight gains corrected for initial weight were greater for single lambs than for twin lambs. The differences in the height at withers were proportional to those in body weight except for the N/N lambs. The N/N lambs had a greater height at withers for their body weight but this could have been the result of factors other than the gene N which were associated with the N–type flock. N–type ewe lambs kept up to 18 months of age maintained lower body weights than +/+ lambs. In 1953 no differences between N/+ and +/+ lambs were found in body growth. It is suggested that a genetic-environment interaction exists for body growth and that the environmental factor is possibly one of climate. No differences were found between the carcass measurements of N/+ and +/+ ram lambs which could not be attributed to the previous differences in body growth.
Studies of the effects of the gene N on body growth and fleece development of the New Zealand Romney. III. Fibre diameter and medullation
Authors: Cockrem F , Rae AL
Published: November 2004

Fibre and medulla diameters were measured of wool samples taken from N/ + and + / + Romney lambs at birth, at 6 weeks, and at 24 weeks of age. Relationships between fibre diameters and density were determined and also the changes in the proportions of kemps, medullated, and unmedullated fibres. From these results possible factors leading to the fleece type at 24 weeks mere analysed. In addition the relationships between medulla and fibre diameters mere calculated. The medulla diameter at a given fibre diameter was higher at birth and 6 weeks than at 24 weeks. At 24 weeks lambs showing poor body growth produced medullated fibres at a lower fibre diameter than did lambs growing well. The significance of these observations is discussed.
Studies on salt tolerance of sheep. II. The tolerance of sheep for mixtures of sodium chloride and magnesium chloride in the drinking water
Authors: Peirce AW
Published: November 2004

Seven groups, each of six sheep, were fed in pens for 16 months on a ration of chaffed lucerne and wheaten hays. One group was offered rain-water to drink, another group was offered 1.30 per cent. sodium chloride, whereas the others were offered one of the following mixtures of sodium and magnesium chlorides : 1.27 + 0.02, 1.24 + 0.05, 1.18 + 0.10, 1.05 + 0.20, and 0.69 + 0.50 per cent. Many of the animals refused to eat or drink satisfactorily when the saline waters were first offered. If, however, the concentrations were increased gradually over a period of 3 weeks to the desired levels, satisfactory performance by most animals was obtained. The intake of water containing 1.30 per cent. sodium chloride was higher than that of rain-water, and the intake increased with increasing concentrations of magnesium chloride up to 0.10 per cent.; the mean daily intakes for the entire experiment by the seven groups were 2.3, 3.9, 4.2, 4.8, 5.0, 4.3, and 3.5 1. respectively. The intake also increased in all groups with temperature, being 60-100 per cent. higher in the hottest months than in the coldest months. A concentration of 1.3 per cent. sodium chloride, and concentrations of up to 0.10 per cent,. magnesium chloride with 1.2 to 1.3 per cent. sodium chloride, had no adverse effect on the sheep, but 0.20 or 0.50 per cent. magnesium chloride (with 1.05 and 0.69 per cent. sodium chloride respectively) was detrimental to some of the sheep. The principal effect was a reduction in food consumption. The only other obvious sign in these last two groups was an occasional diarrhoea; this was more frequent on the higher concentration of magnesium chloride. The saline drinking waters had no effect on the concentrations of sodium, potassium, calcium, or chloride in the blood plasma. Magnesium, however, was significantly higher, throughout most of the experiment, in the plasma of the sheep which received 0.50 per cent. magnesium chloride.
The medullation characteristic of the hair coat as a factor in heat tolerance of cattle
Authors: Dowling DF
Published: November 2004

Measurements of the hair fibres of the cattle coat show, besides considerable seasonal variation in the length, diameter, and weight of hair per unit area, marked changes in the incidence and degree of medullation, which may account for the required variation in the thermal effect of piliary development associated with seasonal conditions. The medulla, a structural component of the hair fibre, may be a critical characteristic of the coat in the regulation of heat dissipation by the animal. The correlation between the incidence of medullation and the animal's ability to regulate the rectal temperature was 0.95.
The efficiency of wool production of grazing Merino sheep
Authors: Weston RH
Published: November 2004

The comparative efficiencies of wool production of a fine-wool and a strong-wool strain of Merino sheep have been studied at pasture. At pasture, the strong-wool strain, although only 22 per cent. heavier in body weight, produced 39 per cent. more clean fleece. It was calculated, with the use of faecal output data. that the strong-wool strain consumed 17 per cent. more feed and produced 19 per cent. more clean fleece per unit of feed consumed. The faeces of the strong-wool strain contained higher concentrations of nitrogen, total ash, and 'silica-free' ash and a lower concentration of crude fibre; this suggested that the feed selected by this strain was slightly higher in nutritive value. Significant differences between strains in digestive ability were sometimes observed, but they were small and inconsistent. It seems likely that, if real differences exist, they will be small. In pens, under controlled conditions of feeding, the strong-wool strain produced 18 per cent. more clean fleece per unit of feed consumed; the measured efficiency of wool production of individual sheep was significantly related to the estimated efficiency of these sheep at pasture. Wool production per unit of body weight may be a useful criterion for selecting efficient wool-producing sheep at pasture.
Cattle ticks, Boophilus microplus, resistant to DDT, BHC, and Dieldrin
Authors: Stone BF , Webber LG
Published: November 2004

Cattle ticks on a property in central Queensland, where there had been a previous history of DDT-resistance, were not readily controlled by dipping infested cattle in 0.05 per cent. w/v gamma-BHC or 0.05 per cent. w/v dieldrin after these chemicals had been in use for 10 and 4 months respectively. Spraying of steers artificially infested with ticks taken from this property 9 months later, indicated resistance to DDT and dieldrin, but not to "Diazinon". Immersion tests with larvae and engorged adult females of this strain showed them to be respectively about 9 and 20 times as resistant to DDT as those of a susceptible reference strain. The engorged females were shown to be more than 700 times as resistant to dieldrin. When tested by an injection method, the engorged adult females of this strain showed a resistance to DDT and dieldrin of 5 and 12 times respectively, some resistance to BHC, but no resistance to Bayer 21/199. Similarly tested engorged adult females of another strain taken from the property 15 months later showed a resistance to DDT of 8 times.
Thyroxine binding in sheep serum
Authors: Annison EF
Published: November 2004

The thyroxine-binding capacities of sheep thyroxine-binding proteins (TBP) can be conveniently measured by reverse-flow electrophoresis. Values were found to be within the range 11-16 µg thyroxine/100 ml serum. No differences could be detected between the patterns of thyroxine binding by the sera of pregnant and non-pregnant sheep maintained under similar conditions of husbandry.
Some aspects of the efficiency of large-scale artificial insemination operations in sheep
Authors: Tallis GM , Young SSY
Published: November 2004

The problems of estimating each day the proportion of ewes coming into oestrus for the first time and the proportion of ewes not returning after the first service have been investigated and discussed in relation to large-scale artificial insemination operations. The results of these theoretical studies were used to examine data from more than 700 Merino ewes which had undergone artificial insemination, and evidence of inefficiency due to an early failure of vasectomized rams was found. From subsequent analyses it was concluded that the methods developed in this paper for estimating conception rates were fairly sensitive and produced satisfactory results.