bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of breeding objectives to prices and genetic parameters in Australian Corriedale and Polwarth dual-purpose sheep
Authors: Fogarty NM , Gilmour AR
Published: March 2005

A profit equation was developed for Australian Corriedale and Polwarth dual-purpose sheep kept for both wool and lamb production. Ten traits contribute to income and costs and were included in the breeding objective. These encompass wool production, fibre diameter, and feed intake of breeding ewes and hogget ewe replacements; sale weight and carcass fat depth of lambs; and reproductive rate and mature weight of ewes. The relative economic value for each trait in the enterprise was calculated from the profit equation using income and costs for 1 year. Overall gain ($A) and gain in each trait in the breeding objective from selection using an index of hogget greasy fleece weight, hogget fibre diameter, dam's number of lambs weaned, lamb weight, and lamb fat depth are reported. The sensitivity of the genetic changes in each trait in the breeding objective and index coefficients were assessed for a range of prices of products and feed costs. Sensitivity to changes in heritabilities and genetic correlations was also assessed. The incorporation of these maternal traits into LAMBPLAN is discussed. For the standard parameters and prices used, gain in leanness accounted for one-third of overall gain ($/ewe. s.d. of selection). Other traits that contributed to overall gain were fibre diameter (28%), reproduction (18%), and growth (14%). There was a small gain through feed intake (8%), and a very small loss in wool weight. Measures of fatness, growth, and fibre diameter were the important traits in the selection index. Inclusion of hogget greasy fleece weight and dam's number of lambs weaned each added <1% to the efficiency of the selection index. Varying the sale price for lamb and the price differentials for fibre diameter and fat depth had the greatest impact on overall gain. High lamb price increased gains in both reproduction and lamb weight, whereas, high price differentials for fibre diameter and fat mainly increased gains in the particular trait. A large range in prices for wool had very little effect on the individual traits or overall. Changing feed costs had little effect on overall gain, although high feed cost reduced gains from reproduction which were compensated by reduced feed intake. Halving the heritability value for each trait reduced overall gain, largely through reduction in the trait. Varying the genetic correlations of wool production with other traits had little effect. However, when genetic correlations of reproduction with weight, fat, and fibre diameter were varied there were changes in overall gain, largely through reproduction.
Effect of grain feeding on fat colour and other carcass characteristics in previously grass-fed Bos indicus steers
Authors: Strachan DB , Yang A , Dillon RD
Published: March 2005

One hundred Brahman cross steers were removed from pasture and fed a high grain diet for a finishing period of 0, 35, 70, 105, or 175 days. The steers were then slaughtered and assessed for subcutaneous fat depth, fat colour, meat colour, marbling, and p-carotene and lutein concentrations in the fat and serum.The average liveweight gain was 0.7 kg/day. After35 days of grain feeding, fat colour was significantly(P<0.05) decreased from 3.9 to 2.4 when assessed using grading chips ranging from 0 (polar white) to 9 (creamy yellow). There was a trend to a further decline in fat colour over longer finishing periods (1.7 at 105 days and 2.0 at 175 days), although 1 steer had a fat colour core of 6 at 70 days and 1 at 105 days slaughter, and another had a score of 4 at 175 days. Steers fed for175 days had higher marbling but darker meat than those fed for the other finishing periods (P<0.05).Subcutaneous fat depth at 105 and 175 days (17.3 mm) was greater than at 35 and 70 days (14.5 mm) and significantly (P<0.05) greater than at the initial slaughter (12.5 mm).Fat colour was correlated (in the subcutaneous and intermuscular fat, respectively) with p-carotene (r = 0.61 and 0.55) and lutein (r = 0.53 and 0.52) concentrations, and in the serum, with p-carotene (r = 0.49) concentration. Objective assessment of fat colour, the Minolta b* value, was also correlated (in the subcutaneous and intermuscular fat, respectively) with p-carotene (r = 0.85 and 0.80) and lutein (r = 0.74 and 0.73) concentrations and was correlated with p-carotene (r = 0.61) concentrations in the serum. It was s demonstrated that grain feeding had an effect on changing bovine fat colour, and although p-carotene was predominant in serum, both p-carotene and lutein contributed to the yellowness in bovine carcass fat.
Muscle score: its usefulness in describing the potential yield of saleable meat from live steers and their carcasses
Authors: Perry D , McKiernan WA , Yeates AP
Published: March 2005

Domestic trade weight steers (149) were assessed visually for subcutaneous fat and then given a live muscle score based on the thickness and convexity of their shape relative to frame size, having adjusted for subcutaneous fat. After slaughter, carcasses were given visually assessed carcass muscle scores based on the same critera. Fat depths at the P8 site and 12-13th eye muscle area were measured. Half of each carcass was boned-out into primal joints with subcutaneous fat trimmed to 6 mm. The weights of these joints plus meat trim (85% visual lean) were added to obtain the weight of saleable meat. The weight of fat trimmed from the carcass, primal joints, and meat trimmings during the bone-out process was added to obtain weight of fat trim. The assessors did not give steers with a greater subcutaneous fat depth better muscle scores when scoring for muscle and intermuscular fat. There was a negative correlation between live muscle score and P8 fat depth (-0.37), and no significant correlation between carcass muscle score and P8 fat depth. The associations between muscle score and yield of saleable meat were investigated using multiple regression techniques, with fat depth and muscle score sequentially added after weight in the model. The coefficient of determination and the residual standard deviation were compared at each stage. For saleable meat yield (kg), liveweight and carcass weight were the main contributors to the variation explained by the models fitted. For saleable meat yield as a percentage of carcass weight, most of the variation accounted for by the models fitted was explained by fat depth, muscle score, and eye muscle area. When added after weight and fat depth in regression models, muscle score significantly increased the coefficient of determination in all cases, with an associated decrease in the residual standard deviation. The effect was strongest for percentage of saleable meat. At the same weight and fat depth, animals or carcasses with better muscle scores produced more saleable meat.
Evaluation of pasture legumes sown into a prepared seedbed at Tamworth, New South Wales. 2. Seed production and seed reserves
Authors: Lodge GM
Published: March 2005

Plots sown in 1983 were used to examine the seed production and reserves (residual hardseeds) of 15 annual legumes over 5 years at Tamworth in northern New South Wales. Seed production characteristics were measured in 1983 for these annuals, and for 6 perennial legumes. After the annuals had set seed in 1983, an area of the plots was sprayed to prevent flowering in subsequent years, and the rates of decline in seed reserves were compared with those from areas that seeded annually. Seed yields of the perennials were often significantly lower than those of the annuals except Trifolium glomeratum. Seed yields of T. subterraneum var. subterraneum cvv. Seaton Park and Woogenellup were significantly higher than those of cv. Nungarin and T. subterrarzeum var. brachycalycinum cv. Clare. Seed numbers were lowest for Medicago scutellata cv. Sava among the annual medics, and for Nungarin among subterranean clovers. There was little relationship between the mean number of seeds produced from 1983-86 and maturity grading, and between seed numbers and relative dry matter yield. Seed reserves decreased over 5 years by more than 90% in the sprayed treatments of all species. This decrease was not continuous, with the largest declines occurring from December 1983 to August 1984. In the sprayed treatments of Seaton Park, Woogenellup, and Clare, and in both treatments of Astragalus hamosus cv. Ioman, Vicia dasycarpa var. villosa cv. Namoi, and T. hirtum cv. Hykon, none of the original 1983 seed was recovered in 1987. For the annual medics and Nungarin, the number of residual hardseeds in the sprayed treatments in 1987 was about 3-5% of the seed produced in 1983. From 1983 to 1987, seed numbers in the unsprayed treatments declined by 7040% for the annual medics and by 85-95% for Seaton Park, Woogenellup, and Clare. Long-term persistence of annual medics and Nungarin depended on seed production in most years and the maintenance of a high number of residual hardseeds in the soil. In contrast, the mid- and late-maturing subterranean clovers Woogenellup and Clare had low seed reserves and were dependent on seed production in most years for their continued regeneration.
Simazine mixtures for control of annual grasses in pastures
Authors: Leys A , Plater B
Published: March 2005

The effectiveness of tank mixes of simazine plus paraquat, and simazine plus fluazifop-P, for control of annual grass weeds in subterranean clover (Trifolium subterraneum L.) pastures was compared in 6 field experiments in southern New South Wales between 1989 and 1991. Mixtures of simazine (500-750 g a.i./ha) plus very low rates of paraquat (40-60 g a.i./ha) gave better than 90% control of vulpia [Vulpia bromoides (L.) S. F. Gray and V. myuros (L.) C. C. Gmelin], barley grass (Hordeum leporinum Link), annual ryegrass (Lolium rigidum Gaud.), and great brome (Bromus diandrus Roth) and were at least as effective as mixtures of simazine plus fluazifop-P (53-106 g a.i./ha). Subterranean clover plant density was not affected by any treatment. Excellent control of grasses caused increased subterranean clover dry matter yields at 1 site and no differences at another site. In weed-free conditions, 12 of 21 herbicide treatments damaged subterranean clover (severe leaf burn and retarded growth) and significantly (P<0.05) reduced dry weight, but this was not reflected in subsequent seed yields.
The etiology of damage to lucerne by the green mirid, Creontiades dilutus (Stal)
Authors: Hori K , Miles PW
Published: March 2005

Green mirid [Creontiades dilutus (Stsl) (Miridae: HEM)] of all developmental stages was found in lucerne throughout December and January 1989-90 at sites near Adelaide, Australia. In the laboratory, they were unable to complete development when given foliage only, but 65% completed development when provided with flowers, from which they fed preferentially on the developing ovules. Only 25% developed from egg to third instar when cut pods were the sole food source but all survivors completed their development on pods thereafter. The insects were observed to make unsuccessful attempts to feed on spotted alfalfa aphid [Therioaphis trifolii (Monell) f. maculata Aphidae (HEM)]. When fifth instars were caged on entire plants, most of the insects were subsequently found near the tops of the plants. Ten adults caged on a head with 7 pods caused them to turn yellow in 5 days, brown in 6, and withered in 7. An adult caged with 2 flowers for 5 h caused both to drop the standard petal and to abort development within the subsequent 24 h. Feeding frequency of fifth instars when given flower heads ad libitum was estimated at 18 times, for a total of 169 minutes, over a 5-h observational period. The saliva contained a pectin, endopolygalacturonase, and its injection into developing ovules and seeds probably accounts for the etiology of damage. The insects' requirement of lucerne seeds and/or ovules to complete its development, its frequency of feeding, and the abscission of whole flowers due to feeding on the ovules probably accounts for the serious losses of seed production previously reported.
Genetic variation within white clover (Trifolium repens L.) populations from north-central Victoria
Authors: Lee CK , Eagles HA , McFarlane NM , Kelly KB
Published: March 2005

A collection of regional white clover (Trifolium repens L.) populations in north-central Victoria was made from 42 farms sown to cv. Irrigation 20-55 years ago. The collection was evaluated for characters known to be associated with productivity and persistence, with the objectives of assessing the extent of genotypic variation within the collection and determining its suitability for a long-term population improvement program for Victoria. Some regional populations of cv. Irrigation have reduced leaf and stolon sizes compared with recently sown and commercial seed farm populations. In a broadbased population derived from this collection, genetic variances and broad sense heritability estimates were high for leaf length and width, and for stolon length, characters related to productivity and persistence. These populations of cv. Irrigation may form the basis of a population improvement program to develop more productive, persistent cultivars for Victoria.
Seasonal variation in lucerne foliar diseases and cultivar reaction to leaf spot pathogens in the field in southern Queensland
Authors: Inch MJ , Irwin JAG , Bray RA
Published: March 2005

Detailed assessments were made of leaf and stem disease incidence and severity on 16 lucerne cultivars and lines over 10 months in the field near Gatton, Queensland (27�34'S., 152�17'E.). The 4 major pathogens encountered were Leptosphaerulina trifolii, Uromyces striatus, Pseudopeziza medicaginis, and Cercospora medicaginis. The diseases caused by these pathogens showed a seasonality in occurrence. Both U. striatus and P. medicaginis were more severe on older shoots, whereas L. trifolii caused highest disease levels on shoots sampled 2 weeks after cutting. The relative rankings of the lucerne entries changed across pathogens, but breeding line MSA showed the best resistance to rust, L. trifolii, and P. medicaginis. This work has indicated that there is genetic variability in disease reaction to foliar pathogens which could be exploited in the development of cultivars for subtropical Queensland.
Effects of postharvest topping, autumn cincturing, and paclobutrazol on growth, yield, and fruit quality of the low chill nectarine cv. Sundowner in subtropical Australia
Authors: George AP , Nissen RJ , Rassmussen T
Published: March 2005

Combinations of 3 methods of controlling tree size (use of the growth retardant paclobutrazol, postharvest topping, and autumn cincturing) were evaluated for their effects on growth, yield, and fruit quality of the low chill nectarine cv. Sundowner in subtropical Australia. Compared with controls over 3 seasons, paclobutrazol used alone reduced tree size by 34-52%, with further reductions when combined with light and severe postharvest topping (by 5-25 and 58-71%, respectively). Yield efficiency (as measured by yield per unit canopy volume) was significantly improved by paclobutrazol and was doubled when paclobutrazol was combined with severe postharvest topping. Although this combination reduced time associated with pruning, thinning, and harvesting, it had the disadvantage of delaying flowering and, consequently, fruit maturity in the subsequent harvest season. Light postharvest topping and autumn cincturing used with paclobutrazol had little effect on yield efficiency, fruit quality, or harvest period. The seasonal pattern of starch reserves for twigs was similar for all treatments, with starch levels falling to a minimum during the early harvest period. Measurements of starch in the major tree organs showed that at very low harvest increments (<10) there was little or no depletion of starch from the twigs and leaves, but as harvest increments increased (range 10-40), there was increasing starch depletion, in order of priority, from the roots, trunks, and limbs.
Fungicidal control of downy mildew (Bremia lactucae) on lettuce
Authors: Wicks TJ , Hall B , Pezzaniti P
Published: March 2005

Field experiments to evaluate fungicides for the control of downy mildew (Bremia lactucae Regel) on lettuce were undertaken because of reports of poor disease control with acylalanine fungicides, and the possible withdrawal from the market of ethylene bisdithiocarbamate fungicides.Of 6 fungicides evaluated, dimethomorph at 0.375 and 0.75 g a.i./L and phosphonic acid at 2.4 g a.i./L were the most effective. Dimethomorph and phosphonic acid controlled downy mildew where acylalanine and, in most cases, acylalanine plus mancozeb formulations were ineffective. The use of lettuce cultivars with resistance to downy mildew and alternating spray programs of either dimethomorph and phosphonic acid should prolong the effectiveness of cultivars and fungicides.
Wool production and heterosis by the Merino, the Polwarth, and their reciprocal crosses
Authors: Butler LG , Horton BJ , Williams PM , Banks RG
Published: March 2005

Tasmanian Merinos and Polwarths were mated in each of 2 years to produce 2 drops of Merino, Polwarth, and F1 reciprocal cross progeny. Polwarths had weaning weights similar to Merinos but were 14% heavier as hoggets. Polwarths grew a similar amount of wool of 11% greater (P<0.001) fibre diameter; however, wool production was 9% less efficient based on metabolic weight. Polwarths displayed an advantage in resistance to footrot. There was a marked Polwarth maternal effect of about 16% on weaning weight but no elfect on hogget weight. The Polwarth maternal effect on fleece weight and efficiency was 9% (P<0.001). In a comparison with a single-born male, ewes weighed 5% less at weaning and 7% less at hogget shearing and produced about 6% less wool (P<0.001), although of comparable fibre diameter. Twins weighed 17% less at weaning, but only 3% less at hogget shearing (P<0.001). They grew about 5% less wool, which was of 2% greater fibre diameter (P<0.001) and 5% higher wool score, but efficiency was 2.5% lower. Production was generally lower (except for yield and wool score) in the 1988 drop than the 1987 drop by 3-10%. Differences in productivity between ram sources were of only slightly lesser magnitude than differences between breeds. The number of feet affected by footrot was reduced by 17% in the 1988 drop. Severe footrot affecting more than 1 foot reduced liveweight but did not significantly reduce fleece weight. There appeared to be some heterosis for weaning weight (10%) and hogget weight (6%), but little heterosis in wool growth (2-3%) or efficiency (-2%).
Superphosphate maintains soil fertility and beef production on grazed white clover pastures in the subtropics. 1. Residual soil phosphorus, sulfur, and nitrogen, and pasture growth responses
Authors: Mears PT , Havilah EJ , Price GH , Darnell RE , McLennan DJ , Wilson C
Published: March 2005

Phosphorus (P) as superphosphate was applied at 0, 12, 24, and 48 kg P/ha each year from 1972 to 1980 to an established white clover (Trifolium repens) and carpet grass (Axonopus affinis) pasture, to measure long-term changes in soil fertility and pasture production under grazing on a duplex soil in a coastal, subtropical environment. Hereford weaner steers grazed the pasture at 2 stocking rates (1.67 and 2.5 steers/ha) from 1972 to 1974, and at 3 stocking rates (1.67, 2.50, and 3.3 steers/ha) for 7 years to 1981. The effects of P and stocking rate during 1972-76 on pasture and animal production were small and variable, so the study was extended to 1980-81 to measure longer term P and stocking rate effects on soil fertility. Available soil P (bicarbonate-extracted) and sulfur (S, phosphate-extracted) responded (P<0.05) linearly over time to rates of maintenance superphosphate. For soil P, this effect increased with time and showed seasonal fluctuations, which were described by a model with linear and curvilinear functions. After 9 years, average soil P levels at the 4 rates of applied superphosphate changed from 32 to 12, 24, 45, and 91 mg P/kg soil, respectively. A residual value function (RVF) was used to predict the residual value of applied phosphorus over time, which fitted the observed values of available soil P for each fertiliser treatment (R2 = 0.99). The soil S response to superphosphate remained constant over time. Mean values at the 4 rates of applied superphosphate were 8, 11, 15, and 25 mg/kg. Over the 9 years, total soil nitrogen increased (P<0.01) linearly from 0.134 to 0.179% and pH decreased (P<0.05) slightly from 5.7 to 5.2, but neither was significantly affected by superphosphate application. Total pasture and clover growth measured in cages responded linearly to superphosphate, with maximum (P<0.05) response occurring in spring each year from 1972-73 to 1976-77. It was concluded that on this duplex soil with 32 mg/kg of bicarbonate-extractable P, omitting superphosphate reduced soil P after 12 months and pasture growth within 18 months. Annual applications of superphosphate from 125 to 250 kg/ha (12-24 kg P/ha) maintained bicarbonate-extractable soil P in the range 24-45 mg/kg and improved growth and seed reserves of white clover in this environment.
Field evaluation of tissue-cultured papaw clones in Queensland
Authors: Drew RA , Vogler JN
Published: March 2005

Field performance of tissue-cultured clones of papaws established either from adult tissue of a high-yielding female plant or from juvenile tissue of seedlings (2 females and 2 hermaphrodites) was compared with seedling controls. All tissue-cultured plants had strong root systems and established more quickly than seedlings. Plants from adult tissue (TCA) had a reduced juvenile phase, as evidenced by increased circumference, lower height of first flower, reduced time to harvest, and higher fruit numbers per metre of stem. Planting date affected node number of first flower for TCA plants but not seedlings. TCA plants had higher yields than seedlings when planted in spring, and this could lead to improved commercial practice. Differences between clones established from juvenile tissue and their respective seedling controls varied and were not consistent with a reduced juvenile phase. Four dwarf off-type plants (<1% of population) originated from a single bud explant.
Effects of ethylene and dehydration on cut flowering stems of Verticordia spp
Authors: Joyce DC , Poole MC
Published: March 2005

The potential for ethylene-induced abscission among Verticordia species used for cut flowers (V. nitens, V. chrysantha, V. plumosa, and V. densiflora) was studied by treating them with 2-chloroethyl-phosphonic acid (ethephon) or exposing them to dilute ethylene gas. The possibility that ethylene production induced by water stress may cause flower abscission was also investigated. Dipping in ethephon (500 or 1000 mg/L) failed to induce flower abscission in V chrysantha or V plumosa. Treatment with ethylene (8.6 pL/L) failed to induce flower abscission in V. densiflora. Ethephon and ethylene both induced substantial flower, pedicel, and leaf abscission in V. nitens. Pretreatment with silver thiosulfate prevented ethylene-induced flower abscission in V nitens. Dehydrating stems for periods of 6, 12, 24, or 48 h at about 20�C did not induce flower abscission in either V plunzosa or V nitens. Dehydration periods of 6 and 12 h had no effect on longevity. Longer drying periods (24 and 48 h) induced early loss in appearance (visual quality) of both species.
Reduced control of powdery mildew (Uncinula necator Schw.) when sterol demethylation inhibiting fungicides are mixed with cupric hydroxide
Authors: Anderson CR , Wicks TJ
Published: March 2005

The efficacy of myclobutanil, triadimenol, and propiconazole was significantly reduced when recommended rates were mixed with cupric hydroxide and applied to control powdery mildew (Uncinula necator) on grape. In 6 field experiments conducted over 2 growing seasons and on 4 grape cultivars, the incidence and severity of powdery mildew on bunches increased following addition of copper to the sterol demethylation inhibiting fungicides. On Rhine Riesling, 4 applications of either 31.25 mg myclobutanil/L or 25 mg triadimenol/L controlled powdery mildew, whereas, 1.25 g cupric hydroxide/L with these fungicides resulted in 53 and 62% of bunches infected, respectively.
A simple and reliable ethylene gassing system for plant studies
Authors: Poole MC , Joyce DC
Published: March 2005

An ethylene permeation system was tested in a study of flower abscission of Verticordia nitens (Lindley) Endl. Various concentrations of ethylene in air were generated by passing air, at a flow rate of 2 L/min, through chambers containing various lengths of polyvinyl chloride (PVC) tubing pressurised (50 kPa) with ethylene. Ethylene permeating through lengths of PVC tubing of 1.5, 15, 150, and 1500 cm (8 mm internal diameter, 1.5 mm wall thickness) gave ethylene concentrations in the outflow airstreams of 0.12, 0.99, 7.8, and 100 �L/L, respectively. Increasing the ethylene pressure in 150-cm-long tubing linearly increased the permeation of ethylene (0.07 �L/L. kPa). A log-linear abscission response of V. nitens flowers to increasing ethylene concentration was demonstrated using this system. Use of silicone tubing (8-mm internal diameter, 1.5-mm wall thickness) resulted in an ethylene flux 75 times that of the same length of PVC tubing. Higher flux through silicone tubing should allow development of ethylene permeation gassing systems suitable for use in fruit ripening and degreening rooms.
Time of joining affects the performance of young Angus and Angus multiply Friesian cattle in the south-west of Western Australia. 2. Calf productivity and its relationship with milk production and reproduction in first-calvers
Authors: Sawyer GJ , Milligan J , Barker DJ
Published: March 2005

In a 3-year study using 183 Angus and 173 Angus x Friesian first-calf heifers, calf birth weight, growth, and efficiency of production were measured for 3 calving times: April (conventional), March (4 weeks earlier), and May (4 weeks later). Measurements included calving outcome; calf birth weights and weight gains; and liveweight, condition, milk yield, and reproductive performance of first-calving dams. Calves born to Angus or Angus x Friesian dams in March or May, respectively, were 1.2 or 1.5 kg heavier at birth than those born in April and were associated with more protracted, difficult calvings and calf losses. Heavier dams gave birth to heavier calves (partial regression coefficient 0.028; value almost doubled for later born calves). Calves born early grew more slowly (by 0.1 kg/day) than calves born at, or later than, the onset of pasture growth (April). The effect was present until weaning but was especially marked at 50-150 days of age. During this period milk production of the dam and available pasture influenced calf growth. Hence, calves from Angus x Friesian dams grew faster (by 0.12 kg/day) than calves from Angus dams until 150 days of age. Thereafter, the difference in growth rate was halved. There was a positive relationship between both liveweight and condition of the 2 breeds of dam at the start of second joining and the growth rate of their calves up to 100 days of age (faster by 0.02 kg/day for every 10 kg dam liveweight). Angus x Friesian dams produced more milk (by about 2.0 kg/day) than Angus dams, resulting in faster growth (by 0.07-0.1 kg/day) of crossbred calves and an advantage of 27.1 kg over Angus calves at weaning. Calf growth and milk yield of dam were significantly associated at 51-200 days for crossbreds and at 51-100 days for Angus. The better milking ability of the crossbred dams did not fully offset the poorer growth made by calves born early. Few calves were suitable for slaughter as weaners for the domestic market. Later born calves grew fastest, but the reduced second conception rates of their dams in restricted joining periods and the lower age of calves at weaning adversely affected total calf productivity following later calving. Similarly, early-born calves grew more slowly and incurred extra production costs through supplementary feeding of their dams with no advantage demonstrated in the fertility of these first-calvers. Varying the time of calving of first-calf heifers from that of the main herd calving around the break of season is not recommended for beef herds relying mainly on seasonal nutrition from pastures.
The performance of Brahman-Shorthorn and Sahiwal-Shorthorn cattle in the dry tropics of northern Queensland. 4. Postweaning growth and carcass traits
Authors: Fordyce G , Loxton ID , Holroyd RG , Mayer RJ
Published: March 2005

Postweaning growth to slaughter at 42 months of age in males and to initial mating at 27 months of age in females was studied in 4 inter se mated Bos indicus crosses in a dry tropical environment. Six-monthly growth periods from weaning (at about 6 months of age) generally coincided with wet and dry seasons. The cattle represented were second and subsequent generations of 112 Brahman and 112 Sahiwal crosses and first backcross and later generations of 314 Brahman and 314 Sahiwal crosses, The Bos taurus component of the crosses was primarily Beef Shorthorn. Annual growth averaged 300 g/day, with annual gain ranging from 60 to 180 kg. Average growth rates were about 50 g/day in the dry season (-352 to +374 g/day) and 500 g/day in the wet season (221-830 g/day). Postweaning growth of Brahman crosses was about 4% higher than Sahiwal crosses, with most of this advantage expressed in wet seasons. Sahiwal crosses were earlier maturing than Brahman crosses. Wet season growth was higher in 314 crosses than in 1/2 crosses, which probably reflected significant environmental stress in this period. Higher growth of 3/4 crosses tended to be maintained during dry seasons. Calves born late in a wet season grew more rapidly in dry seasons than early-born calves, so that liveweight differences which were apparent at weaning were reduced by one-third at 24 months of age. The difference between liveweights of weaners with young dams and those with mature dams was also reduced from 12-18 kg to 5-6 kg by 24 months. Dressing percentages of 3/4 cross steers at slaughter were 0.6 units higher than in half crosses, with no difference between Brahman and Sahiwal crosses. Sarcomere lengths, Warner-Bratzler shear force values, and Instron compression values together showed that M. longissimus dorsi muscle samples from 1/2 Brahman steers were the most tender of the breed crosses studied. Samples from Sahiwal cross and 3/4 Brahman steers appeared most affected by connective tissue toughness. Those from 3/4 Sahiwals appeared most affected by meat processing factors, causing them to be the least tender.
Beef production from Hereford and Angus multiply Hereford steers grazed separately at two stocking rates
Authors: Morgan JHL , Bird PR , Watson MJ , Clark AJ , Cumming KN
Published: March 2005

An experiment was conducted to examine the relative postweaning growth and carcass characteristics of Hereford and first-cross Angus x Hereford steers at 21 months of age. Twenty steers of each type were bred from Hereford cows calving in autumn (March) and weaned in December 1981 at9 months of age. Thereafter, the 2 groups were grazed separately and set-stocked at 1.64 or 2.73 steers/ha until t he following January, at 21 months of age. The experiment was repeated using the same design for the982 calves but with groups interchanging paddocks at the start.The breed types did not differ significantly in liveweight gain (for 1982 and 1983, respectively, Herefords gained 138 and 202 kg, and Angus x Herefords 139 and 217 kg) or in carcass characteristics in either year. Herbage mass was very similar in the paddocks grazed by the 2 groups (e.g. at the end of the first and second years grazing, respectively, pasture mass was 1.7 and 3.2 t/ha for Herefords, and 1.7 and 2.8 t/ha for Angus x Herefords). There were no differences between the breed types for digestibility and intake of pasture, or in body composition. 1 These results show that no penalty is incurred in the growth and carcass composition of steer progeny if Hereford cows are crossed with Angus bulls.
The timing of birth in grazing Merino sheep
Authors: Alexander G , Stevens D , Baker P , Bradley LR
Published: March 2005

During a 5-year study of lambing behaviour involving almost 1900 births by grazing ewes, the incidence of lambing peaked during the 5-h period 0900-1400 hours, when 28% of ewes lambed. Significant numbers of births occurred throughout the day, and so effective supervision of lambing would not be possible if attendance was restricted to daylight hours. The birth process was clearly delayed when the unlambed sheep were moved slowly from 1 paddock to another. The apparent tendency for ewes to lamb in clusters was shown to be largely the outcome of the exponential distribution expected for the intervals between consecutive, randomly occurring events, but a small significant excess of short intervals above those expected indicates that environmental factors may operate in the synchronous triggering of parturition.
Comparison of the performance of subterranean clover cultivars in southern New South Wales. 2. Effects of Phytophthora clandestina and bromoxynil on seedling survival, growth, and seed set
Authors: Dear BS , Murray GM , Cregan PD , Taylor PA
Published: March 2005

Effects of the root disease caused by Phytophthora claiidestina were assessed at Wagga Wagga on 14 cultivars of subterranean clover (Trifolium subterraneum) following application of the herbicide bromoxynil. Seedling death over autumn-winter ranged from 22% in Trikkala, the most resistant cultivar, to 96% in Woogenellup, the most susceptible. Compared with previous years (1984-85), herbage yields and seed set of the most susceptible cultivars were depressed. Cultivars with the most severe disease symptoms (Woogenellup, Nungarin, Northam) did not set seed. Later maturing cultivars (Karridale, Enfield) appeared to recover from the disease and set more seed than earlier maturing cultivars (Dalkeith, Daliak) with similar reactions to P. clandestina. Field susceptibility (determined by leaf damage scores, seedling losses, and dry matter yield depression) was similar to glasshouse phytophthora ratings for most cultivars; however, Trikkala, Karridale, and Enfield were more affected in the field following herbicide application than expected from the glasshouse reaction. Trikkala, Junee, and Dalkeith were the cultivars most tolerant in the field to root rot, while Woogenellup, Northam, and Nungarin were the most severely affected. Leaf damage following herbicide application was greatest in cultivars showing the most severe root lesions and having the highest susceptibility to P. clandestina in a glasshouse test. P. clandestina reduced the productivity of susceptible subterranean clover cultivars and has the potential to reduce long-term persistence by reducing seed set.
Response of wheat, triticale, barley, and canola to lime on four soil types in north-eastern Victoria
Authors: Slattery WJ , Coventry DR
Published: March 2005

Lime requirement curves based on relative yield and pH data for 4 soil types were derived to estimate the amount of lime required to reach maximum yield for wheat, triticale, barley, and canola. Simple equations expressing lime requirement as a function of soil pH accounted for >90% of the variation in applied lime on 3 soil types (red brown earth, red podsolic, podsolised red earth). When aluminium and manganese (0.01 mol CaCl2/L extracted) were included in these equations, either individually or together, they did not improve the relationship significantly for these 3 sites; however, manganese significantly improved the predictability of lime for solodic soil. A comparison of this model with a laboratory-based model showed good correlation for 3 soils (red brown earth, red podsolic, podsolised red earth), but the laboratory method underestimated the field lime requirement of solodic soil.
The impact of genotype multiply environment interactions for sugar yield on the use of indirect selection in southern Queensland
Authors: Mirzawan PDN , Cooper M , Hogarth DM
Published: March 2005

To develop a strategy to improve the efficiency of selection, indirect selection and pattern analysis were used to examine the magnitude and form of genotype x environment (GE) interactions for sugar yield in sugarcane clones in southern Queensland. Clone x location interactions were the predominant source of clone X environment interactions and were much larger than clone x crop-year and clone x location x crop-year interactions. Both the indirect selection study and the pattern analysis emphasised the relative magnitude of these sources of interactions. Pattern analysis strongly associated crop classes at each location, and indirect selection analysis emphasised an opportunity to exploit correlated genetic advance between crop classes within a location. These suggest that more emphasis should be placed on sampling a greater number of locations than on the testing of clonal ratooning ability within locations. This would improve the chances of obtaining both broadly and specifically adapted sugarcane varieties.
A grower survey of diseases, invertebrate pests, and pesticide use on potatoes grown in South Australia
Authors: Dillard HR , Wicks TJ , Philp B
Published: March 2005

In 1991, a survey was distributed to 251 potato growers in South Australia to determine major diseases, insect and other invertebrate pests, and chemicals used to control them. The overall response rate was 48%, but of these, 24 individuals were no longer growing potatoes. The results were summarised for the State and by district (Adelaide Hills, Adelaide Plains, Murray Lands, South East). The most prevalent diseases encountered by respondents in all districts were target spot caused by Alternaria solani, and rhizoctonia canker caused by Rhizoctonia solani. Other diseases of concern to growers included late blight caused by Phytophthora infestans, seed piece decay caused by various pathogenic and saprophytic microorganisms, common scab caused by Streptomyces scabies, and leaf roll caused by potato leaf roll virus. The most commonly used fungicides for disease control were chlorothalonil (33-42% of respondents), mancozeb (30%), and cupric hydroxide (11-13%). The most commonly used seed treatments for control of seed piece decay were mancozeb (51 % of respondents), tolclofos methyl (24%), and lime (20%). Green peach aphid (Myzus persicae), potato aphid (Macrosiphum euphorbiae), potato moth (Phthorimaea operculella), and jassids and leafhoppers (Jassidae, Cicadellidae) were the pests of greatest concern to the growers. Others included Rutherglen bug (Nysius vinitor), redlegged earth mite (Halotydeus destructor), and thrips (Thripidae). The most commonly used insecticides were ethamidophos (40% of respondents), monocrotophos (22-28%), and dimethoate (7-13%).
Postharvest handling of cut immature Eucalyptus foliage
Authors: Jones RB , Truett JK , Hill M
Published: March 2005

Optimum postharvest and storage treatments were investigated for cut immature branches of Eucalyptus crenulata Blakely & Beuzev. and Eucalyptus gunnii J. D. Hook. The application of the germicide BCDMH at 10 mg/L of active chlorine, 100 �L Agral-600/L. or 0.25% sucrose to vase solutions significantly enhanced vase life in E. crenulata Longevity in E. gunnii was significantly extended by sucrose (0.25-2% w/v), but not by germicides or Agral. Sucrose pulses (1-10% for 24 11 at 20�C) or exogenous ethylene (50 �L/L for 24 h at 20�C) had no effect on the longevity of either species. Both species produced very low levels of ethylene immediately after harvest and after a 24-h simulation of dry transport at 20�C. Longevity was not significantly altered in either species by 35 days of dry storage at 1�C. or by 7 days of wet storage (branches held in distilled water + 50 mg DICAJL) at 1�C, but declined significantly in both species after 7 days of wet storage at 10�C.
Australian grass-fed beef for Japan. 1. Carcass quality characteristics, saleable meat yield, and the value of various carcass measurements for predicting yield
Authors: Hopkins DL , Roberts AHK
Published: March 2005

Fifty-six carcasses from grass-fed steers of 4 breed types, purchased for the Japanese market, were evaluated for quality and yield characteristics. The mean (� s.d.) carcass weight was 324 � 28.3 kg, and P8 fat depth 16.5 � 5.27 mm. Based on the Japanese grading system. 52 of the carcasses were considered acceptable for marbling, 54 for fat colour, and all carcasses for meat colour. The mean marbling, fat colour, and meat colour scores were 3.3, 3.3, and 3.5 respectively. The rank correlation between P8 fat depth and marbling score was 0.09, and a similar level of association was found between marbling score and fat depth measurements at other positions on the carcass. Measures of M. longissimus thoracis et lumborum (LD) area, using different techniques at the same rib, were significantly (P<0.001) correlated (5th rib, r = 0.87; 10th rib, r = 0.80); however, there was no association between LD area at the 5th and 10th ribs. Models were developed to predict the weight of saleable meat (SM) and fat trim (FT) based initially on hot standard carcass weight (HCW) and P8 fat depth as the independent variables. For all models HCW was the important predictor, with various measures of subcutaneous fat depth increasing the accuracy of estimates by a small amount. Fat depth measurements from the loin region reduced the error of prediction of SM more than fat depth measurements from the rump region, irrespective of the method used to measure fat depth. Replacing fat depth measures with the weight of trimmed fat significantly improved the accuracy of the predictions. The best model for predicting FT weight was based on the predictors HCW and fat depth at the 12th113th rib. Breed type was found to be not significant (P = 0.07) if included in a model with P8 fat depth and HCW. When breed type was included, P8 fat depth was no longer significant. When LD area at the 10th rib was included with HCW and P8 fat depth as a predictor of SM, P8 fat depth was no longer significant (P>0.05), but this was not the case when estimates of LD at the 5th rib were used. Regardless of this, estimates of LD area at both ribs showed themselves to be useful predictors of SM additional to HCW and P8 fat depth. Breed type was not a significant (P>0.05) contributor to the model based on the predictors HCW, P8 fat depth, and LD area at the 10th rib. If fat depth at the 10th rib was used with HCW and LD at the 10th rib instead of P8 fat depth, then more of the variation (R2 = 0.88 v. 0.85) in SM was explained and the error of the prediction was less (3.34 v. 3.75). Also, when fat depth at the 10th rib was used, the rib site used to estimate LD area was less important. The models showed that prediction of SM in heavyweight carcasses was marginally aided by using estimates of LD area.
Requirement of field pea for inoculation with Rhizobium and lime pelleting in soils of Western Australia
Authors: Evans J , Wallace C , Dobrowolski N , Pritchard I , Sullivan B
Published: March 2005

The requirement of field pea (Pisum sativum) for seed inoculation with Rhizobium and for lime pelleting of inoculated seed was investigated in field experiments in the south-west of Western Australia, especially at locations where inoculated field pea had been grown 2 years previously. At most sites with previous pea cropping, the nodulation, total dry matter and nitrogen, and grain yield of pea were not improved by seed inoculation or lime pelleting. At these sites soil populations of R. leguminosarum by. viciae at sowing were >103/g soil. Responses to inoculation were measured at sites where the soil was very acidic [pH(CaCl2) <4.5], or mildly acidic (to pH 4.9) and of light texture (>90% sand + gravel), or where pea had not grown previously. There were fewer rhizobia at sowing at these locations. Lime pelleting was not generally required to maximise field pea growth or yield, but yield was affected by the inoculant Rhizobium strain.
Effects of girdling time on growth, yield, and fruit maturity of the low chill peach cultivar Flordaprince
Authors: Allan P , George AP , Nissen RJ , Rasmussen TS
Published: March 2005

Low chill Flordaprince peach trees in subtropical Australia were trunk-girdled at 1 of 3 times during fruit development: pre stone hardening (pre SH), post stone hardening (post SH), and 2 weeks before expected first harvest (BFH). Measures were made of fruit and shoot growth, harvest data, and starch levels in different tree parts. The pre SH girdling gave the greatest (P<0.05) increase in fruit size during stage 2 of fruit development, and pre and post SH girdling treatments gave progressively earlier (P<0.05) and shorter (10 days v. 24 days for control) main harvest period. Girdling resulted in greater numbers of fruit of larger, desirable marketable size (>90 g) than the control, although the latter caught up in average yield because of longer development period and some variability in numbers of fruit per tree. Split pip was not a problem. Fruit sugar content was significantly (P<0.05) higher with post SH and BFH girdling treatments than with control or pre SH treatment. Girdling temporarily increased starch levels in the leaves and shoots and reduced shoot growth.
Effects of growth regulants on defoliation, flowering, and fruit maturity of the low chill peach cultivar Flordaprince in subtropical Australia
Authors: George AP , Nissen RJ
Published: March 2005

The growth regulants paclobutrazol, hydrogen cyanamide (Dormex 500 g a.i./L), and potassium nitrate were tested for their effectiveness in promoting earlier and more even budbreak, flowering, and fruit maturity of the low chill peach cultivar Flordaprince in subtropical Australia. Paclobutrazol advanced harvest by about 10 days. Hydrogen cyanamide was effective in advancing fruit maturity by about 19 days, but even at the lowest concentration used (5 mL/L), it severely reduced fruit set by >4 0 % . In contrast, 1-3 sequentially autumn-applied potassium nitrate sprays advanced flowering by about 10 days; >3 applications caused significant (P<0.05) yield reductions (29%).
Effect of gypsum, deep ripping, and irrigation on determinate tomatoes
Authors: Muller AT
Published: March 2005

Treatments of gypsum, deep ripping, and level of irrigation were applied to alluvial soils at Carnarvon, Western Australia, to assess the effect on yield of determinate tomatoes. Yield was increased (P<0.05) from 3 1.9 to 41.5 t/ha when gypsum (5 t/ha) was applied and increased (P<0.05) with level of irrigation (65.6 t/ha at 699 mm v. 14.9 t/ha at 270 mm). Blossom end rot and total soluble solids in fruit were significantly (P<0.05) higher at low and medium irrigation (355 mm) levels than at the high level. Total soluble solids increased significantly (P<0.05) when gypsum was applied to deep-ripped treatments. Dispersion of soil colloids was significantly (P<0.05) reduced by gypsum. Deep ripping to 0.6 m removed the soil hardpan but had no effect on tomato yield or dispersion.