bluuebunny/crossref_metadata_2025 huggingface dataset:
Positive relation between substitution rate and pasture allowance for cows receiving concentrates
Authors: Grainger C , Mathews GL
Published: March 2005

Pasture substitution rates were measured when cows were offered a grain-based concentrate at pasture allowances of 8, 17 and 33 kg DM/cow.day. Thirty-six cows in their first month of lactation were allocated to 6 groups in a 6x6 Latin square design. There was a significant interaction between supplementation and pasture allowance for pasture intake and milk yield. Pasture intake decreased by 0,0.25 and 0.69 kg pasture DM/kg concentrate DM eaten, at pasture allowances of 7.6, 17.1 and 33.2 kg DM/ cow.day. The increases in milk yield from feeding concentrates were greater at lower pasture allowances: 0.97, 0.69 and 0.28 L/kg concentrate DM eaten at pasture allowances of 7.6, 17.1 and 33.2 kg DM/ cow.day respectively. A highly significant linear relation between pasture intake at zero concentrate intake and pasture substitution rate (SR) was established from these and other published data [SR = -0.445 + 0.3 15 (�0.057)PI, where PI is pasture intake (kg DM/ cow.day. 100 kg liveweight)]. This relation quantifies the effect of unsupplemented pasture intake on pasture substitution rate and consequently on the milk yield response to supplementing the diet of cows with concentrate.
No-till crop establishment on red earth soils at Katherine, Northern Territory: effect of sowing depth and firming wheel pressure on the establishment of cowpea, mung bean, soybean and maize
Authors: Abrecht DG
Published: March 2005

The effect of sowing depth and firming wheel pressure of a no-till planter on the emergence and seedling growth of soybean, cowpea, mung bean and maize was examined in a red earth soil at Katherine, Australia. Each species was planted in a factorial combination of 3 sowing depths (60, 80, 100 mm) and 3 seed firming wheel pressures (1, 6, 11 kg/cm tyre width). Hot, dry conditions for 14 days after sowing resulted in rapid drying of the soil and high soil temperature. Most seed germinated but there was considerable variation in seedling emergence. Good seedling emergence of mung bean (96%) and cowpea (95%) contrasted with poorer emergence of soybean (57%) and maize (50%). Maize germinated more slowly than the grain legumes and unemerged seedlings had ceased growing when the coleoptiles were < 10 mm long. Soybean germinated rapidly and hypocotyls of the unemerged seedlings had stopped growing within 20 mm of the soil surface. The development of maize and soybean seedlings may have been retarded by high temperatures and severe soil water deficits. Deep planting slowed emergence but increased seedling growth in maize and soybean. The effect was most evident in soybean. Firming wheel pressure did not influence the soil strength below the planted seed and did not significantly affect seed germination, seedling emergence or seedling growth.
Effects of fungicide seed dressings and fungicide-treated fertiliser on the severity of leaf diseases and yield of barley in Western Australia
Authors: Khan TN , Young KJ
Published: March 2005

Standard and increased rates of seed dressings with triadimenol, flutriafol and experimental formulations of flutriafol, and triadimefon and flutriafol coated on double superphosphate and drilled at sowing were assessed for control of leaf diseases of barley (Hordeum vulgare L. cv. Stirling). Scald, (Rhynchosporium secalis (Oud.) Davis), powdery mildew (Erysiphe graminis f. sp. hordei March.) and Drechslera verticillata (O'Gara) Shoem. appeared in various experiments. Fungicide-coated fertilisers provided the most disease control for the longest duration, triadimefon coated fertiliser increasing yield by up to 30%. Fungicide-treated fertilisers therefore show great promise in increasing the level and duration of disease control as well as the yield of barley where foliar diseases are known to be a problem.
Effect of season (vegetative flushing) and leaf position on the leaf nutrient composition of Annona spp. hybrid cv. Pink's Mammoth in south-eastern Queensland
Authors: George AP , Nissen RJ , Carseldine ML
Published: March 2005

Seasonal patterns of leaf nutrient concentrations and leaf sampling procedures were established for the Annona spp. hybrid cultivar, Pink's Mammoth in subtropical Queensland (27�S.). One group of nutrients showed a general decline in concentration in the leaves with time (K, 1.448%; P, 0.3-0.15%) while another group showed an overall increase (Ca, 0.4-1.4%; Mg, 0.3-0.54%; B, 24-66 �g/g). Nitrogen leaf levels decreased throughout the growing season (3.5-2.5%), with the pattern of decline strongly influenced by vegetative flushing. Leaf concentrations of Ca, Mg, Mn and B generally increased, and N, P, K, Cu, and Zn decreased with leaf age. Movement of the more mobile elements (i.e. N, P. K, Cu, and Zn) from the older into the younger leaves was more rapid when trees were flushing compared with trees that had completed flushing. Irrespective of the state of flushing, higher concentrations of the less mobile elements Mg, Ca, B and Mn were recorded in the older compared with the younger leaves, indicating that their movement into younger leaves is relatively slow. Our results suggest that the most suitable time to sample leaves is after the completion of vegetative flushing when the concentration of most leaf elements have stabilised. Depending on the element, it may be more appropriate to sample either young or old leaves rather than compromise by sampling only the most recently mature, fully expanded leaf.
The relation between time of sowing of cereals and cereal cyst nematode (Heterodera avenae Woll.)
Authors: Georg DG , Fisher JM , Dube AJ , Wayte SE
Published: March 2005

Many juveniles of Heterodera avenae Woll. were hatchable in April but hatching was inhibited by lack of water. Number of knots (infestations) per susceptible wheat plant in 1981 increased from less than 40 at the initial sowing in mid-May to a maximum of almost 80 in mid June sowings; in 1982, the maximum (80 knots/plant) was recorded at the initial sowing in late April. Loss in yield of grain of wheat and barley was minimal in crops sown in mid-May but rapidly increased to a maximum in crops sown in late May/early June, the optimum time of sowing for yield. This maximum loss changed little in crops sown up till early August and varied with the tolerance of the cultivar from 520 to 880 kg/ha. Early or late sowings reduced potential yield. Females with eggs first appeared on the roots 90 days (late July) after sowing, indicating that fallows to prevent reproduction of the nematode should begin in early August. Maximum numbers of females (16lplant) occurred in sowings at the optimum time for yield (late May/early June) and decreased in later sowings. Resistance in the host reduced numbers of females but applications of ethylene dibromide rarely did.
An evaluation of the Hennessy Grading Probe for measuring fat depth in beef carcasses
Authors: Hopkins DL
Published: March 2005

Fat depth at the P8 site on the rump was measured by the cut-and-measure (CM) technique and with the Hennessy Grading Probe (HGP) on 2501 beef carcasses at 1 abattoir over a 12-month period. CM measurements that differed by more than 1 mm between the right and left sides of the carcass were discarded. A subsequent data set of 1850 carcasses was randomly divided so that 2 models could be developed to assess the general validity of the relationship between the 2 methods of measurement. Analysis of measurements of the left side of the carcasses of these 2 subsamples showed the data were not normally distributed. Removal of outliers at the 95% confidence level and also measurements at both extremes of the data range improved the symmetry of the sets of data. From each adjusted data set, regression equations were developed to predict CM measurements from HGP measurements. Linear equations were adequate for predicting CM measurements from HGP measurements, and curvilinear analysis did not improve the predictions. Compared with the curvilinear equations, the linear equations resulted in smaller differences between the 2 data sets for the predicted CM measurements over a range of HGP measurements.
Effect of phosphorus on the specific gravity of potato tubers (Solanum tuberosum L.) of cultivars Kennebec and Coliban
Authors: Maier NA , Potocky-Pacay KA , Dahlenburg AP , Williams CMJ
Published: March 2005

The effect of phosphorus banded at planting, at rates up to 240 kg/ha, on the specific gravity of tubers of cvv. Kennebec (10 sites) and Coliban (5 sites) was investigated using field experiments conducted during 1984-85, 1985-86 and 1986-87. The relationship between specific gravity and phosphorus concentration in petioles of youngest fully expanded leaves (P-YFEL) was also determined.
As the rate of applied phosphorus increased there were significant positive and negative trends in specific gravity. However, the size of the effect varied between sites; for example, the maximum and minimum ranges in specific gravity (based on treatment means) due to phosphorus application were 1.0762-1.0869 (site 13) and 1.0753-1.0772 (site 24), respectively for the cv. Kennebec and 1.0598-1.0683 (site 22) and 1.0715-1.0753 (site 17), respectively for the cv. Coliban. Rates of applied phosphorus, which resulted in maximum specific gravity, also varied between sites. Maximum specific gravities occurred at phosphorus rates in the ranges 0-100 and 40-240 kg/ha for cvv. Kennebec and Coliban, respectively.
There were significant relationships (5 quadratic and 1 negative linear) between phosphorus concentration in P-YFEL and specific gravity for cv. Kennebec at all 6 responsive sites. Phosphorus concentrations in P-YFEL associated with maximum specific gravities were in the range 0.29-0.51%. For cv. Coliban, over similar tissue phosphorus concentration ranges, there were significant (P<0.05) positive linear relationships for 1 responsive and 2 non-responsive sites.
When data for cv. Kennebec were pooled for all sites, there was a significant (P<0.05) quadratic relationship between specific gravity and tissue phosphorus concentration (range 0.22-0.77%). For the cv. Coliban the trend was not significant (P>0.05).
We have concluded that the rate of phosphorus banded at planting can affect specific gravity and that the cvv. Kennebec and Coliban differ in their sensitivity to this effect.
Influence of high energy supplements containing fatty acids on the productivity of pasture-fed dairy cows
Authors: King KR , Stockdale CR , Trigg TE
Published: March 2005

Three groups of 8 cows in their second month of lactation grazed irrigated perennial pasture alone, or grazed and were supplemented with either 3.3 kg/day of a high energy supplement or 3.8 kg of a high energy supplement containing additional long-chain fatty acids. Yields of milk and milk products were generally highest for those cows fed the supplement containing fat. Yield of milk fat was 13% higher in fat supplemented cows than those in the other supplemented treatment because these cows overcame the negative effect of starch supplements on milk fat test. Inclusion of long-chain fatty acids in the diet caused only minor changes in the fatty acid composition of the milk fat and in the various rumen parameters. The immediate marginal increases in daily yields of milk and milk fat per kg of long-chain fatty acids consumed by cows were 1.8 and 0.33 kg/cow. After comparison with data from other experiments, we concluded that the type of basal diet is not an important factor influencing the response of dairy cows to dietary long-chain fatty acids
Effect of additions of nitrogen and sulfur to irrigated wheat at heading on grain yield, composition and milling and baking quality
Authors: Randall PJ , Freney JR , Smith CJ , Moss HJ , Wrigley CW , Galbally IE
Published: March 2005

The effects of adding nitrogen (N) and sulfur (S) to wheat (Triticum aestivum L. cv. Matong) at heading on the concentrations of nutrients in the plant, on grain and flour composition and milling and baking quality were studied. The crop was grown on a red- brown earth in the Goulburn Valley irrigation area of northern Victoria. There were 2 application rates of urea, 0 and 50 kg N/ha combined factorially with 2 application rates of calcium sulfate, 0 and 20 kg S/ha.Additions of N increased the concentrations of both N and S in the grain and increased protein level, but grain N:S ratio remained unaffected. Sulfur application had no effect on grain composition or on flour or dough properties. A standard range of baking tests showed that the extra protein synthesised was functional protein contributing to the dough properties in an additive manner. The N treatment lowered the hot paste viscosity and the brightness of the cold paste suggesting that there was a qualitative effect on the starch component as well as a lowering of starch content as the protein increased. There was no indication of any deleterious effects on quality arising from the late application of N as has been found by other workers.
Copper deficiency in ruminants in the South East of South Australia
Authors: McFarlane JD , Judson GJ , Gouzos J
Published: March 2005

Pasture development in the South East of South Australia has depended upon trace element enriched fertiliser applications. Despite the wide usage of copper-enriched fertilisers, copper deficiency is still evident in livestock at pasture, particularly cattle. Serum collected from cows and heifers during the systematic sampling program of the Brucellosis and Tuberculosis Eradication Scheme was analysed for copper. Of the 3611 pooled herd samples analysed, approximately 9% had low serum copper concentrations (<7 �mol/L). Distribution of those herds identified to be at risk of copper deficiency appeared to be random, apart from areas of high risk on peat soils and the coastal fringe of calcareous sands. Analysis of pasture samples collected from paddocks with cattle having low serum copper concentrations showed that low serum copper was usually associated with raised molybdenum rather than low copper concentrations in pasture. In some instances, moderate concentrations of molybdenum and sulfur in pasture and soil ingestion associated with high iron concentrations may combine to cause hypocupraemia, especially when livestock graze stubbles and subterranean clover pastures in summer-autumn and short pastures in winter. Only 6% of pasture samples had less than 4 mg Cu/kg DM, a concentration which indicates possible copper deficiency in subterranean clover or strawberry clover.
Evaluation of herbicides for control of summer-growing weeds on fallows in south-eastern Australia
Authors: Leys AR , Amor RL , Barnett AG , Plater B
Published: March 2005

Eighteen herbicides or herbicide tankmixes were evaluated over 3 years (1987-89) for their control of 11 important summer-growing weeds on fallows in southern New South Wales and the Wimmera area of Victoria. Each of the weeds was effectively controlled by at least 1 herbicide. The tank-mixes of glyphosate plus metsulfuron (270 + 4.2 g a.i./ha) and glyphosate plus 2,4-D ester (270 + 320 g a.i./ha) were the most effective treatments, each giving an average of 68% control of all species. Hogweed (Polygolzunz avicu1ar.e L.), prickly paddy melon (Cucumis myriocarpris Naudin), spear thistle [Cirsium vulgare (Savi) Ten.] and skeleton weed (Chondrilla juncea L.) were the species most tolerant of these 2 tank-mixes. When these species were exluded, glyphosate plus metsulfuron and glyphosate plus 2,4-D ester gave an average of 90 and 88% control, respectively, of the remaining species [common heliotrope, Heliotropiunz europaeum L.; camel melon, Citrullus larzatus (Thunb.) Matsum. and Nakai var. lanatus; prickly lettuce, Lactuca serriola L.; sowthistle, Sonchus spp.; clammy goosefoot, Chenopodium pumilio R.Br.; caltrop, Tribulus terrestris L.; stink grass, Eragrostis ciliatiensis (All.) E. Mosher]. Hogweed was most effectively controlled by 2,4-D amine plus dicamba (750 + 100 g a.i./ha) or 2,4-D ester (800 g a.i./ha); prickly paddy melon by 2,4-D amine plus triclopyr (750 + 96 g a.i./ha); spear thistle by 2,4-D amine plus dicamba (750 + 100 g a.i./ha) or glyphosate plus clopyralid (270 + 60 g a.i./ha); and skeleton weed by 2,4-D amine plus clopyralid (750 + 60 g a.i./ha). A pot experiment confirmed field observations that, as common heliotrope ages, glyphosate and glyphosate plus metsulfuron become less effective for its control.
Effect of soil nitrate on the growth and nodulation of lupins (Lupinus angustifolius and L. albus)
Authors: Cowie AL , Jessop RS , MacLeod DA , Davis GJ
Published: March 2005

The effect of increasing external nitrate (NO-3) concentration on the nodulation of Lupinus albus and L. angustifolius lines was examined in 2 sand culture experiments. In the first experiment 4 lines, 3 L. albus and 1 L. angustifolius, were grown at NO-3 concentrations of 0, 2, 8, 16, and 30 mmol/L for 49 days. Increasing the NOT concentration reduced nodule weight in all varieties to a similar extent. In a second experiment, 18 L. angustifolius lines were grown at NO-3 concentrations of 2 and 8 mmol/L for 49 days. The ratio of nodule weights at the 8 and 2 mmol/L NO-3 treatments varied widely, from 23 to 71%, between the lines. There appears to be potential for selection of L. angustifolius varieties able to maintain N2 fixation at increased levels of soil N.
Responses in cotton yields to nitrogen and phosphorus fertilisers in the Emerald Irrigation Area, central Queensland
Authors: Hibberd DE , Ladewig JH , Hunter MN , Blight GW
Published: March 2005

The poor growth of cotton in the Emerald Irrigation Area of central Queensland was investigated in fertiliser experiments from 1978 to 1980. The need for large amounts of phosphorus (P) and nitrogen (N) fertilisers was demonstrated. In a glasshouse nutrient-omission experiment, N, P, potassium, sulfur (S), zinc, copper, manganese, boron (B) and molybdenum were tested for effects on cotton growth on the soil surface fraction (low in P and S) of a black cracking clay at Emerald. Plant growth indicated that P, N and S were extremely deficient. Other nutrients, except B, were marginally deficient. Slow growth was reflected in low shoot concentrations of N, P and S. In subsequent field experiments at 5 sites on 3 different soils, yield responses were only obtained to applications of P and N. Phosphorus at a rate of 40 kg/ha was required on a shallow, basaltic, dark cracking clay (Bug) soil. Yield responses to P were not obtained on an alluvial, dark cracking clay (AUg) or on a deep, basaltic, dark cracking clay (TbUg), but soil P concentrations were generally higher at these sites. For high value cotton crops where soil P analyses are low (i.e. <12 mg/kg bicarbonate-extractable P at 0-10 cm), high P fertiliser rates are recommended to maintain the soil P status. Nitrogen at a rate of 120 kg/ha produced heaviest yields on the Bug soil, but there were symptoms of N deficiency in plants early in the season. Irrigation frequency treatments produced no significant differences in yield.
Variation in oil concentration and economic return from tea-tree (Melaleuca alternifolia Cheel) oil
Authors: Murtagh GJ , Etherington RJ
Published: March 2005

The oil concentration in tea-tree (Melaleuca alternifolia Cheel) twigs was measured over 8 consecutive days during November 1987, and over 10 out of 12 consecutive days in January 1989. The oil concentration, measured in units of volume of oil per unit dry weight of twigs (v/DW), varied markedly between successive days, from 2.9-1.8% v/DW (a 38% decrease) to 1.8-3.4% v/DW (a 89% increase). The reason for such variation is unknown but it had a pronounced effect on the profitability of growing the crop. The profit, which was expressed as a return on the total set-up cost of $A17 2591ha, was estimated for each of the measured oil concentrations and fixed values of biomass yield, the price of oil and average production costs. The extreme daily variations in oil concentration mentioned above caused the return on investment to decline by 11 percentage points and increase by 16 points, respectively. When measured at the same site, the mean oil concentration increased from 3.1% vPW in November 1987 to 5.8% v/DW in January 1989. As a consequence, the respective mean returns on investment increased from 0 to 26%.
Grazing management studies with Australian cashmere goats. 2. Effect of stocking rate on the liveweight gain of sheep and goats grazing an oats-rye grass pasture
Authors: Norton BW , O'Grady FT , Hales JW
Published: March 2005

Australian cashmere goats and Border Leicester x Merino sheep grazing an oats-rye grass pasture were used to study the effects of stocking rate (20, 40, 60 animals/ha) on growth, intestinal parasite burdens and haematology of the 2 species and on the persistence and productivity of the crop grazed. Goats and sheep were either grazed alone or together over a 12-week period to determine the interaction between the species. Liveweight gain decreased with both stocking rate and time on experiment. At the highest stocking rate all animals lost weight between weeks 9 and 12. During the first 9 weeks of grazing, sheep had significantly (P<0.05) higher liveweight gains than goats at all stocking rates; but the rate of decline in liveweight gain with increased stocking rate was similar in both species, whether they were grazed alone or together. Mean values for sheep were 161, 133 and 105 g/day, and for goats 101, 84 and 59 g/day at stocking rates of 20, 40 and 60 animals/ha. Under the same drenching regime, goats were more severely infested by intestinal parasites than sheep as indicated by significantly (P<0.05) higher concentrations of parasite eggs in faeces and lower packed cell volumes and haemoglobin concentrations in blood. Oats was the major contributor to green feed available at all stocking rates, although rye grass yields increased in the later stages of the trial, particularly in high stocking rate paddocks. At the end of the trial, high yields of oat stem remained in the paddocks grazed by goats and goats plus sheep, suggesting that sheep grazed both leaf and stem but goats selectively grazed oat leaf. The availability of green leaf (oat + rye grass) per animal was closely related to liveweight gain in any period, although these relationships were different for sheep and goats.
Genetic aspects of cold resistance and related characters in newborn Merino lambs
Authors: Slee J , Alexander G , Bradley LR , Jackson N , Stevens D
Published: March 2005

Resistance to body cooling and rate of recovery from induced hypothermia were measured in 287 single, newborn Merino lambs from 24 different sire families, using a water bath test in which partly immersed lambs were progressively cooled. Birth weight, birthcoat type (fine-hairy) and skin thickness were recorded at the time of test. There was an unexpected occurrence of congenital goitre, the incidence and severity of which was estimated by manual palpation of the thyroid gland. Heritability (� s.e.) of cold resistance (CR), estimated by paternal half-sib analysis, was 0.70 � 0.25. Sex of lamb, type of weather, time of test, Fecundin treatment and age of ewe were fitted in the model as fixed effects but none were significant. Other heritable traits (h2 � s.e.) included birthweight (0.50 � 0.22), birthcoat grade (0.61 � 0.24), coat depth (0.62 � 0.24), skin thickness (0.35 � 0.19) and the severity of goitre (0.21 � 0.16). Significant genetic correlations (r �s.e.) between cold resistance and other traits were: birthweight, +0.76 � 0.18; birthcoat grade, +0.56 � 0.24; birthcoat depth, +0.56 � 0.24; skin thickness, +0.51 � 0.27; goitre, -0.58 � 0.40. Most of the corresponding phenotypic correlations were small. Goitre did not affect CR significantly, despite the genetic correlation between them. Heritability of CR, further adjusted for the effects of birthweight, birthcoat grade and depth, and skin thickness as covariates, was 0.55 � 0.23. About 40% of the variation in CR was accounted for by fitting fixed effects and covariates, but significant sire effects remained. Rate of recovery from hypothermia was not heritable and it was unrelated to any other variable except goitre, which tended to be associated with slower recovery (rp = 0.18). It was concluded that genetic selection for increased CR would succeed but would promote birthcoat hairiness unless a corrective selection index was used. The relationship between birthcoat type and CR was considered to be mediated by genes affecting both coat type and CR, not primarily by a direct effect of coat insulation.
Effects of once-yearly weaning on some aspects of herd productivity in an extensive herd in the semi-arid tropics of northern Australia
Authors: Sullivan RM , O'Rourke PK , Robertson DJ , Cooke D
Published: March 2005

Cow reproductive rates, mortalities and liveweights, and steer growth rates from a herd of 500 Bos indicus - Bos taurus cross cows and their progeny were recorded over a period of 4 years from June 1981. The cattle grazed native pastures and were not supplemented. Cows which had a calf of more than 100 kg in June were allocated to 2 treatments: weaned and unweaned. Where the calf weighed less than this amount, cows were allocated to a separate 'young calf group. In the year following branding, weaning increased (P<0.05) conception rate from 73.9 to 93.8% and reduced (P<0.05) cow mortality rate from 14.1 to 4.5%, relative to the unweaned group. On average, weaned cows conceived 3 months earlier (P<0.05) than the other 2 groups, in November, and 27% of weaned cows subsequently calved out of season the following year, compared to 4% of the other groups. This affected subsequent weaning management by increasing the number of calves too young to wean in June. Weaned steers grew at a reduced (P<0.05) rate during the first year post-weaning. Despite compensatory gain in the next 2 years, they were still 26 kg lighter (P<0.05) than their unweaned counterparts at 3.5 years of age.
Evaluation of rootstocks for Eureka and Lisbon lemons in replant ground in New South Wales
Authors: Sarooshi RA , Broadbent P
Published: March 2005

The yield, growth, fruit quality, and graft compatibility of 2 lemon cultivars Eureka and Lisbon [Citrus limon (L.) Bum. f.], budded onto several new rootstocks, were studied in replant ground.Promising rootstocks for Eureka lemon were 2 new hybrids bred at Gosford, New South Wales, 3798 (Scarlet mandarin x Poncirus trifoliata) and 4017 (Smooth Seville x P. trifoliata), and also Benton citrange and Nelspruit hybrid 639. Trees on the sour orange group of rootstocks including Xingshan, Dai Dai and Baggan yielded 44-63% less than trees on rough lemon rootstocks; but their fruit quality, as evidenced by juice per cent, OBrix, and citric acid (kg/t), was better. The performance of Lisbon lemon was tested on 10 selections of F'. trifoliata, and although trees on Flying Dragon were smaller and yielded about 50% less than on Swingle, Christiansen, Large Flower, and selection 22, results were not significantly (P<0.05) different.
Implantation and recovery of identification transponders in the anal region of steers
Authors: Hasker PJS , Round PJ , Slack DJ
Published: March 2005

Ninety-eight steers were implanted subcutaneously in the anal region with identification transponders to determine the feasibility of recovering the transponders at slaughter. Groups of 20, 19, 19, 20 and 20 steers were slaughtered 1, 35, 71, 105 and 175 days after implanting. At the first slaughter, 7 transponders were lost when the anal sphincter was removed during hide removal. At subsequent slaughterings, leaving the anal sphincter intact and removing it with a 150 mm section of rectum at the viscera table resulted in the recovery of at least 17 transponders in each group. Those not found in the rectal section were recovered from the carcass. No migration of transponders from the implant site was observed. Histological examination of tissues surrounding the transponders indicated that encapsulation had begun by 35 days after implant.
Determination of critical nitrogen concentrations of potato (Solanum tuberosum L. cv. Sebago) grown in sand culture
Authors: Huett DO , White E
Published: March 2005

A gamma x cubic response surface model was used to predict the dry matter yield of potato cv. Sebago over the 12-week growth period in sand culture with nitrogen (N) levels of 2, 7, 14, 29 and 43 mmol N/L. At each 2-week sampling period after emergence, dry matter yield relative to maximum was plotted against tissue N concentration to derive diagnostic petiole, petiole sap, leaf nitrate-N and leaf total N in youngest fully opened leaf (YFOL), youngest fully expanded leaf (YFEL) and oldest green leaf (OL) and for total N in bulked leaves. Critical concentrations corresponding to 90% maximum yield are presented. Tissue nitrate was much more responsive than leaf total N to applied N over the 2-14 mmol/L range where positive growth responses to N were recorded. Plants grown with 2 mmol N/L were severely N deficient and growth was depressed. Tissue nitrate concentrations in these plants from 4 weeks after emergence onwards were negligible, while leaf total N concentrations exceeded 2.36%. Salt toxicity occurred at 29 and 43 mmol NIL, and it sometimes reduced tissue N concentrations so that adequacy and toxicity concentrations overlapped. Critical tissue N concentrations declined over the growth period, the largest decline occurring for nitrate. Critical tissue N concentrations for YFEL, from 2 weeks after emergence to final harvest were: petiole sap nitrate-N, 1.2-0.2 g/L; petiole nitrate-N, 2.1-0.1%; leaf nitrate-N, 0.44-0.08%. Critical tissue nitrate concentrations clearly differentiated between inadequate and adequate N application levels. Critical leaf total N concentrations only differentiated between inadequate and marginal N application rates, except for OL when inadequate and marginally adequate (80-90% maximum yield) concentrations were not different (P>0.05). Nitrogen application level affected (P<0.05) leaf potassium, phosphorus, calcium (Ca), magnesium (Mg) and sulfur concentrations. The largest effects were recorded for Ca and Mg where increasing N application level reduced leaf nutrient concentration. Petiole sap nitrate concentrations can be used as a rapid field test for distinguishing between a deficient and an adequate N supply. Where concentrations exceed critical values, they can be interpreted as such because N fertiliser toxicity rarely occurs under field conditions.
Crop production on duplex soils: an introduction
Authors: Turner NC
Published: March 2005

Duplex or texture-contrast soils occur over about 60% of the agricultural areas of south-west Western Australia. Annual crops of wheat, barley, oats, and lupins predominate on these soils, grown in rotation with annual pastures. The climate is characterised by cool, wet winters and hot, dry summers. Crop production is restricted to the winter and spring and is limited by waterlogging in the wet winter months and by water shortage during grain filling in spring. Research on crop production on duplex soils has been undertaken for the past 8 years by a collaborative team from the CSIRO Dryland Crops andyoils Program and the Western Australian Department of Agriculture. This research has been focussed on 3 sites at which processes limiting crop production on duplex soils have been highlighted. This special issue was initiated to summarise that research and to put it in its regional and national perspective. Additionally, opportunity was taken to compare and contrast experiences both within Western Australia and throughout Australia, and to draw out management options for crop production on duplex soils.
Acidification problems of duplex soils used for crop-pasture rotations
Authors: Coventry DR
Published: March 2005

The acidification of duplex soils used for crop-pasture rotations has been reported widely in Australia in the winter dominant rainfall regions. At some locations induced soil acidity limits crop and pasture yield. The rate of soil acidification is affected by soil properties, agricultural management and rainfall. Rates of acid addition of 0.6-6 kmol H+/ha.year have been measured from long term crop pasture rotation experiments; these rates are comparable with values reported from pastoral studies in higher rainfall areas. Components of both the carbon and nitrogen cycles contribute to this acid addition, with loss of nitrate nitrogen below the rooting depth of these predominantly annual plant systems likely to be the main cause of acidification. Lime application has been recommended as a means of correcting acidification and improving crop and pasture yield. There is little information on the longevity of any beneficial effects of lime, the movement of lime in the soil and re-acidification of the soil in crop-pasture systems. A long term experimental site with rotation, deep tillage and lime treatments has been soil sampled throughout a 9-year period for changes in soil pH and aluminium. Soil pH decreased with increasing time after lime application. At lower lime rates (0.5-1.0 t/ha) there was no difference in pH or exchangeable A1 after 9 years, compared with the unlimed soil. At the higher lime rates there was downward movement of the neutralising effect of lime with time, as well as acidification of the soil. However, the yield responses obtained with all of the lime rates were maintained 9 years after 1 application of lime, even though the soil was strongly acid according to the measures used. Strategies for countering soil acidificaton may require an initial application of lime if acidity factors are restricting yield. Management systems which increase the permeability of the B horizon of duplex soils and which promote plant growth and a deep root system are essential for countering acidity in a croppasture rotation.
Yield responses to lime of phalaris, cocksfoot, and annual pastures in north-eastern Victoria
Authors: Ridley AM , Coventry DR
Published: March 2005

Yield responses of 3 mixed grass-clover pastures [Phalaris aquatica L. cv. Sirosa (phalaris), Dactylis glomerata cv. Porto (cocksfoot), and annual grass based Trifolium subterraneum L. cv. Trikkala (subterranean clover) pastures] were measured over 5 soil pH treatments at 2 sites in Victoria. One site (Beechworth) was strongly acidic [pH(CaCl2) < 4.21 to a depth of 40 cm and contained high concentrations of soil aluminium (Al). At the other site (Lake Rowan), yield responses to lime application had been measured previously, but only in Al-sensitive wheat cultivars. At Beechworth, pasture yield responses to lime were not consistent but. when observed. occurred in autumn and winter in all 3 pasture types. Phalaris pastures showed yield increases more often than cocksfoot and annual pastures. Low magnesium and calcium concentrations may have limited dry matter production, although yields were reasonable on all treatments. Where lime was applied, growth responses may have been due to alleviation of Al toxicity. At Beechworth, pasture yield was increased where lime increased pH from 4.2 to 4.6 and decreased soil Al (measured in 10 mmol CaCl2/L) from 11 to <3 �g/g soil. Herbage manganese concentrations were not high in phalaris and subterranean clover, and cocksfoot manganese standards were not available. At Lake Rowan (pH 4.7, Al <1 �g/g), no growth responses to lime were seen in any pasture treatment, and annual grass based pastures sometimes had higher yields than phalaris and cocksfoot pastures. On strongly acidic soils such as at Beechworth, incorporation of lime prior to pasture establishment should be considered. Perennial grasses may reduce further soil degradation through acidification. Soil A1 concentrations are commonly lower in ley-cropping areas, and the inclusion of perennial grasses in ley pastures requires further evaluation.
Influence of method of conservation of lucerne on factors associated with voluntary intake in sheep
Authors: Etheridge MO , Stockdale CR , Cranwell PD
Published: March 2005

This experiment measured the voluntary intake and rate of eating of sheep fed lucerne (Medicago sativa) that had been conserved as sun-dried material or as silage at 3 different DM contents (29.2, 33.1, and 51.2%). Changes in rumen osmolality and palatability due to diet were measured. Palatability was assessed by introducing feed directly into the rumen and measuring the subsequent oral intake. Eight sheep with rumen fistulae were used in two 4 x 4 latin squares, which allowed for adjustment for carryover effects. There was no significant (P<0.05) difference between voluntary intakes of lucerne conserved as sundried material and as silages of various DM contents (mean intake 1189 g DM/day). The lack of difference in intake was attributed to the high quality of fermentation of the silages. Rate of eating was also generally similar for all diets. Evidence from measurements of palatability and rumen osmolality support these observations. Palatability appeared not to influence the voluntary intake of any of the diets, because the sheep reduced their daily oral intake by an amount similar to that introduced into the rumen. Under normal feeding conditions, rumen osmolality was also similar for all feeds and was relatively consistent for the 9 h immediately after the start of feeding. While rumen osmolality per se may affect voluntary intake, the lack of response reported here for changes in osmolality due to diet support the lack of response reported for feed consumption.
Reduction of chilling injury in grapefruit and oranges stored at 1°C by prestorage hot dip treatments, curing, and wax application
Authors: Wild BL
Published: March 2005

Chilling injury in Marsh grapefruit during storage at 1�C was reduced 61% by dipping in hot water(50�C) for 2 min before storage. The fungicide thiabendazole (TBZ) at 1000 mg/L applied as a cold dip(14�C) reduced the susceptibility of these fruit to chilling injury by 28% over an 8-week storage period. Susceptibility of Washington navel oranges to chilling injury was reduced 65% after dipping in hot TBZ (50�C) for 2 min. Wax application and prestorage curing for 1 week at 20�C also reduced chilling injury damage. Where there is a risk of chilling injury in fruit to be disinfected against fruit fly, the risk can be reduced by dipping in a hot TBZ suspension at 50�C. A thorough application of wax has also been shown to reduce the I susceptibility of citrus fruit to chilling injury.
Subclinical selenium insufficiency. 5. Selenium status and the growth and wool production of sheep supplemented with thyroid hormones
Authors: Donald GE , Langlands JP , Bowles JE , Smith AJ
Published: March 2005

Fine wool Merino sheep grazed pastures low in selenium (Se) in 2 experiments, and were supplemented with Se and thyroxine (T4) in experiment 1, and with Se, T4, and tri-iodothyronine (T3) in experiment 2. Both experiments ran for 6 months. In experiment 1, 72 sheep with a mean liveweight of 37 kg were given Se by intraruminal pellet and 6 levels of T4 ranging from 0 to 10 mg sodium L-thyroxine as a subcutaneous injection at 14-day intervals. In experiment 2, 36 sheep with a mean liveweight of 24 kg were given Se by intraruminal pellet, and 3 levels of T4 ranging from 0 to 0.4 mg and 3 levels of T3 ranging from 0 to 0.1 mg by subcutaneous injection at weekly intervals. In both experiments wool production and mean fibre diameter were significantly increased by Se supplementation; the increase in clean fleece production was 7 and 32% in experiments 1 and 2, respectively. In experiment 1, T4 increased greasy fleece weight by up to 8% and reduced yield, mean fibre diameter, and liveweight. In experiment 2, T4 reduced fibre diameter. T3 did not significantly affect wool production, wool characteristics, or liveweight. There was no significant interaction between Se and thyroid hormone supplementation in either experiment. Thyroid hormones were used as effectively for wool production by both Se-deficient and Se-sufficient sheep.
Subclinical selenium insufficiency. 6. Thermoregulatory ability of perinatal lambs born to ewes supplemented with selenium and iodine
Authors: Donald GE , Langlands JP , Bowles JE , Smith AJ
Published: March 2005

The ability to resist cold stress was evaluated in 70 perinatal Merino lambs using a partial immersion technique. Their dams grazed pastures low in selenium (Se) and received sodium selenate supplements every 14 days (0-8 mg Se). Half of the ewes also received 100 mg potassium iodide every 14 days from the end of the first trimester of pregnancy. Selenium supplementation of the dam increased blood and plasma Se concentrations in the lamb and reduced thyroxine (T4) and increased tri-iodothyronine (T3) concentrations in plasma. The T4 to T3 ratio declined from 39 to 21 as the Se supplement was increased. These relationships were asymptotic. Selenium status did not affect the time taken for rectal temperature to fall to 35�C when the lambs were immersed in a water bath of progressively declining temperature, or to rewarm when removed from the water. Lambs born to ewes supplemented with iodide tended to have higher mean rectal temperatures during cold stress but this trend, and most selenium x iodine interactions, were not significant.
Effects of sowing time and grazing on the dry matter yield, phenology, seed yield, and hardseed levels of annual pasture legumes in western New South Wales
Authors: Young RR , Morthorpe KJ , Nicol HI , Croft PH
Published: March 2005

Fifteen annual pasture legumes [Medicago truncatula cvv. Jemalong, Cyprus, Paraggio, Sephi, Parabinga, plus fixed lines SAD 6699, SAD 6766, SAD 7883; M. aculeata lines SAD 2325, SAD 2356; M. scutellata cv. Sava; M. laciniata (cutleaf medic) local ecotype Cl2; Trifolium subterraneum cvv. Nungarin, Dalkeith, Seaton Park] were sown at Condobolin at 6 times in autumn and winter 1986 and periodically grazed at 3 levels of intensity (nil, until flowering, until pod formation). Late sowing greatly reduced (P<0.001) the weight of 50-day-old plants, more so for some varieties (e.g. Cyprus) than others (e.g. Dalkeith, SAD 2325). Seed size accounted for most of the variation (R2 = 0.92) in the weight of plants with 1-2 trifoliate leaves. Total dry matter yields were reduced (P<0.001) by later sowing and grazing, and there were interactions between both of these factors and variety. The subterranean clovers yielded most dry matter and Cyprus and Sava least. Dry matter yields of SAD 6699 and cutleaf medic were reduced least by grazing. Time from sowing until flowering was shorter with later sowing times. With later sowing times, the order of flowering of early-maturing varieties changed, and the difference between the earliest and latest varieties fell from 100 to 11 days. Grazing delayed flowering by up to 2 weeks. All treatments and interactions affected (P<0.001) seed yield. Seed yields were highest (>100 g/m2) in ungrazed early-sown plots and were reduced (P<0.001) at later sowing times by grazing until pod formation for all sowing times for all varieties, and by grazing until flowering for some varieties. Cutleaf medic, Nungarin, and Dalkeith had superior seed yields under adverse conditions of grazing and late sowing. Spring dry matter yields accounted for 90% of the variation in seed yields. There was no optimum dry matter yield for maximum seed yield (except SAD 7883 at 778 g/m2 and cutleaf medic at 275 g/m2) under mild spring conditions, and flowering time did not account for variation (P>0.05) in seed yields at any sowing time. Seeds on previously ungrazed plots progressively softened between 8 December 1986 and 8 March 1987, with those of Jemalong, Cyprus, Parabinga, SAD 6766, cutleaf medic, Dalkeith, and Seaton Park softening more rapidly on later sown plots.
Effects of subsurface drainage, cultivation, and stubble retention on soil porosity and crop growth in a high rainfall area
Authors: Gardner WK , Drendel MF , McDonald GK
Published: March 2005

Wheat, triticale, and rapeseed growth and yield were studied under various tillage (conventional, deep ripping, direct drilling) and stubble-handling (burnt, retained) regimes with and without drainage at Hamilton in south-western Victoria from 1985 to 1987. Grain yield was increased from about 2 to >4 t/ha by drainage in both years; however, effects of other treatments, although significant, were much less. Soil structure (as measured by fractional air-filled porosity at -5 J/kg) deteriorated during winter and recovered during spring and summer. A laboratory experiment showed that this variation in soil structure resulted from saturation per se and redrying. In the field, the decline in porosity was most pronounced with cultivation and the absence of drainage, but overall, the effects of stubble retention and tillage treatments were small. There was a significant positive relationship between yield and porosity on undrained areas, but not where drains were present. Drainage reduced soil structural decline during winter, while stubble retention reduced the decline in porosity in the cultivated-undrained treatment in 1987.
Comparison of the prediction of carcass components using fat thickness measurements in heifers and steers
Authors: Johnson ER
Published: March 2005

Predictions of carcass composition based on anal fold and 12th rib fat thickness measurements were compared in 12 Hereford heifers and 12 Hereford steers. For carcass proportions, simple regression equations indicated that heifers had less muscle (2-3%), more fat (2.5-4%), and more bone (0.9%, 12th rib only). Empty liveweight did not improve the accuracy of prediction of any carcass component when added to anal fold fat thickness. Chilled carcass weight and 12th rib fat thickness slightly improved the accuracy of prediction of muscle and fat proportions compared with prediction using each measurement alone. Multiple regression indicated that the heifers had 2.5-3% less muscle and 34% more fat. For predictions of the weights of carcass components at a given fat thickness measurement, simple regression indicated that heifers had less muscle than steers (by about 6 kg), but for bone and fat the intercepts did not differ significantly between sexes. In multiple regression, empty liveweight contributed strongly to the predictions of weights of all 3 carcass components. In all regressions in which the weight of each of the 3 carcass components was regressed on a weight and a fat thickness measurement together, except for muscle and fat regressed on chilled carcass weight and 12th rib fat thickness, the fat thickness measurement failed to contribute significantly to prediction. Although chilled carcass weight and 12th rib fat thickness together contributed (P<0.01) to the prediction of muscle weight and fat weight, chilled carcass weight was the stronger contributor. Regression indicated that heifers had about 3 kg less muscle and 3.5 kg more fat than steers. Multiple regression analysis showed that heifers and steers had about the same weight of bone.