The vectorial and dispersal capacities of flies make them a biosecurity and food safety risk on egg farms. The design of optimal control and biosecurity programs requires knowledge of species composition and patterns of abundance of the fly populations present. Although there have been many studies of flies breeding on egg farms in other countries there is little information available in Australia. We monitored numbers and species of flies breeding on cage egg farms in southern Australia and used mass marking with fluorescent resin dye to assess the dispersal of the major species from one of the farms. The main peak in fly numbers occurred in spring and early summer and was comprised predominantly of little house flies (Fannia canicularis). Significant numbers of false stable flies (Muscina stabulans) were trapped near accumulated manure, but relatively low numbers were present in bird housing areas. House flies (Musca domestica) were found in only low numbers or were absent at most times of the year. In the dispersal studies, 85% of marked F. canicularis and 67% of marked M. stabulans were trapped within 255 m of the layer sheds. The greatest distance from the farm at which marked F. canicularis flies were captured was 739 m for traps and 1.25 km for tapes whereas M. stabulans flies were trapped at all distances including in the most distant trap nearly 2 km from the farm. Modelling of trap catches by distance predicted maximum dispersal distances of 1.6 km for F. canicularis and 2.4 km for M. stabulans.

The in vivo faecal egg count reduction test (FECRT) is the most commonly used test to detect anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) of ruminants in pasture based systems. However, there are several variations on the method, some more appropriate than others in specific circumstances. While in some cases labour and time can be saved by just collecting post-drench faecal worm egg counts (FEC) of treatment groups with controls, or pre- and post-drench FEC of a treatment group with no controls, there are circumstances when pre- and post-drench FEC of an untreated control group as well as from the treatment groups are necessary. Computer simulation techniques were used to determine the most appropriate of several methods for calculating AR when there is continuing larval development during the testing period, as often occurs when anthelmintic treatments against genera of GIN with high biotic potential or high re-infection rates, such as Haemonchus contortus of sheep and Cooperia punctata of cattle, are less than 100% efficacious. Three field FECRT experimental designs were investigated: (I) post-drench FEC of treatment and controls groups, (II) pre- and post-drench FEC of a treatment group only and (III) pre- and post-drench FEC of treatment and control groups.

World consumption of fresh pineapple has quadrupled in less than 15 years (Loeillet and Pacqui, 2009). This phenomenal event started around 1996 when the first dedicated fresh market pineapple, '73-114', was released by Del Monte Inc. This was the culmination of somewhere in the vicinity of 34 years of breeding and selection and comprised 24 individual parent combinations (Anon., PRI breeding records). This demonstrates the difficulty of breeding new pineapple cultivars but also the value of a successful program. The success of '73-114' and the competitive nature of world pineapple markets have provided impetus for pineapple breeding programs. However, the highly heterozygous nature and self-incompatibility of pineapple limit breeding strategy options. This review looks at the collective experience in pineapple genetic improvement both conventional and using biotechnology tools, with an emphasis on fresh market pineapple. It focus on relevant pineapple reproductive biology, breeding strategies, parent cultivars and the relevance of biotechnology.

Faecal Egg Count Reduction Tests (FECRTs) for macrocyclic lactone (ML) and levamisole (LEV) drenches were conducted on two dairy farms in theSubtropical, summer rainfall region of eastern Australia to determine if anthelmintic failure contributed to severe gastrointestinal nematode infections observed in weaner calves. Subtropical Cooperia spp, were the dominant nematodes on both farms although significant numbers of Haemonchus placer were also present on Farm 2On Farm 1, moxidectin pour-on (MXD) drenched at 0.5 mg kg(-1) liveweight (LW) reduced the overall Cooperia burden by 82% (95% confidence limits, 37-95%) at day 7 post-drench As worm burdens increased rapidly in younger animals in the control group (n = 4). levamisole was used as a salvage drench and these calves withdrawn from the trial on animal welfare grounds after sample collection at day 7. Levamisole (LEV) dosed at 6 8 mg kg(-1) LW reduced the worm burden in these calves by 100%. 7 days after drenching OnFarm 2, MXD given at 0 5 mg kg(-1) LW reduced the faecal worm egg count of cooperioids at day 8 by 96% (71-99%), ivermectin oral (IVM) at 0.2 mg kg(-1) LW by 1 6% (-224 to 70%) and LEV oral at 7 1 mg kg(-1) LW by 100%. For H placer the reductions were 98% (85-99.7%) for MXD, 0.7% (-226 to 70%) for IVM and 100% for LEVThis is the first report in Australia of the failure of macrocyclic lactone treatments to control Subtropical Cooperia spp and Suspected failure to control H placer in cattle Crown Copyright (C) 2009 Published by Elsevier B.V All rights reserved

Control of sheep lice with conventional pesticides can be compromised by difficulty in contacting lice in the dense water repellent fleeces of sheep, particularly when sheep have not been recently shorn. Entomopathogenic nematodes (ENs) are motile and are able to actively seek out insect hosts. They have particular advantages for the control of pests in cryptic habitats, such as the fleeces of sheep and avoid many of the problems frequently associated with chemical controls. This study investigated whether ENs were able infect and kill Bovicola ovis and compared the effectiveness of different species at different temperatures and when applied to wool.Four species of nematodes, Steinernema carpocapsae, Steinernema riobrave, Steinernema feltiae and Heterorhabditis bacteriophora were tested. All were shown to infect and kill lice in Petri dish assays at 30 degrees C. At 35 degrees C. the percent infection for S. carpocapsae and S. riobrave was significantly higher than for the other two species and percent infection by S. feltiae was significantly greater than for H. bacteriophora (P<0.05). At 37 degrees C the percent mortality induced by S. riobrave was significantly greater than for S. carpocapsae (P<0.05). All species were able to locate and infect lice in wool when formulated in water with 8% Tween 80. In wool assays the percent lice infected with nematodes was significantly greater for S. riobrave than H. bacteriophora at 25 degrees C, but there were no other differences between species (P=0.05). S. carpocapsae, S. riobrave and S. feltiae caused significantly higher lice mortality than H. bacteriophora at both 25 and 35 degrees C in wool assays, but mortality induced by the three steinernematid species did not differ significantly (P>0.05). It is concluded that of the ENs studied S. riobrave is likely to be most effective against B. ovis when applied to live sheep because of its greater tolerance to high temperatures and 'cruiser' foraging strategy. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

Testcrosses were made with novel sources of lucerne germplasm. These were evaluated in the field in a subtropical environment to identify the lines which produced the highest yielding hybrids as a guide to future breeding efforts. The novel sources were derivatives of Medicago sativa × M. arborea partial (asymmetric) hybrids (termed sac) and very highly winter-active Omani landraces of M. sativa. As testers, 2 lines were used; a Colletotrichum trifolii race 2 resistant selection from the group 9 Australian-bred and adapted cultivar PacL 901 (selection hereafter termed 901) and the Omani landrace, Oman 2, collected at 17°N latitude, from Salalah, Oman. In the row experiment, substantial and significantly positive tester parent heterosis for overall yield (sum of 13 harvests) was observed in all of the sac × Oman 2 testcrosses, with the mean performance of the 11 testcrosses (1839 g/m row) significantly (P < 0.05) exceeding the mean performance of the sac × 901 testcrosses (1703 g/m row) evaluated. Where 901 was used as the tester, heterosis values relative to the tester for the same sac lines were negative for all testcrosses with 8 of the testcrosses being significantly negative. For the Omani landrace × 901 testcrosses, positive and negative heterosis values for total yield relative to the tester were observed, but none were significantly different from zero. The 901 tester yielded significantly (P < 0.05) more per se than the Oman 2 tester (1956 v. 1470 g/m row), although in an adjacent sward experiment Oman 2 yielded comparably to most of the standard commercial cultivars. The potential of the novel germplasm in the subtropics was verified in sward experiments with synthetics and/or strain crosses with yield increases of up to 42% over the benchmark synthetic Sequel. Further improvements can be expected following selection for disease and pest resistance within the lines and in the case of Oman 2 and sac, converging to maximise complementary gene action.

Performance of lucerne cultivars and breeding lines, when grown under irrigation in the Queensland subtropics in individual experiments and when averaged over the 25 years from 1981 to 2006, is presented. In the overall analyses, only cultivars which were entered in at least 2 experiments were included. Entries were evaluated in small plot cutting experiments over 3-year periods. Seasonal, annual and total dry matter yields were recorded, along with field disease assessments and persistence. Highest seasonal, annual and total (60–64 t/ ha) yields were produced by highly winter-active cultivars (activity levels 8 and 9) with little differences between Sequel, Sequel HR, Hallmark, Sceptre, Aquarius and Pioneer L90, although yields of a number of Queensland-bred cultivars with lower activity levels (<8) were not signifi cantly lower. Individual experiments were more discriminating, with the Queensland-bred cultivars Sequel and Trifecta producing the highest (P<0.05) or equal to the highest yields in 8 of 10 and 9 of 14 experiments in which they were included, respectively. Other high-yielding cultivars included Aquarius, Aurora, Genesis, Hallmark, Pioneer L55, Sceptre and UQL-1. Average winter yields ranged from 1.7 t/ha for Hunter River to 3.2 t/ha for Hallmark, while the range in individual experiments was larger (1.1–5.7 t/ ha), taking into account the range from dormant to highly active material. Disease played a significant role in defining production levels until the drought years of 2001–2006, when the effects of colletotrichum crown rot (CCR), phytophthora root rot (PRR) and the leaf disease complex of Stemphylium vesicarum and Leptosphaerulina trifolii were reduced. Trifecta was consistently in the group of cultivars showing most resistance to these diseases, while Hunter River showed equal or better resistance to colletotrichum crown rot and the leaf disease complex. On average, only 12 – 20% of the original populations survived until the end of the third year, with Hallmark, Trifecta and Sequel consistently the most persistent cultivars. There was a wide range in persistence between experiments (general mean of 29% in 1984 compared with 5% in 1995), with environmental conditions appearing to play as important a role as disease resistance.

Remote drafting technology now available for sheep makes possible targeted supplementation of individuals within a grazing flock. This system was evaluated by using 68 Merino wethers grazing dry-season, native Mitchell grass pasture ( predominantly Astrebla spp.) as a group and receiving access to lupin grain through a remote drafter 0, 1, 2, 4 or 7days/week for 8 weeks. The sole paddock watering point was separately fenced and access was via a one-way flow gate. Sheep exited the watering point through a remote drafter operated by solar power and were drafted by radio frequency identification (RFID) tag, according to treatment, either back into the paddock or into a common supplement yard where lupins were provided ad libitum in a self-feeder. Sheep were drafted into the supplement yard on only their first time through the drafter during the prescribed 24-h period and exited the supplement yard via one-way flow gates in their own time. The remote drafter operated with a high accuracy, with only 2.1% incorrect drafts recorded during the experimental period out of a total of 7027 sheep passes through the remote drafter. The actual number of accesses to supplement for each treatment group, in order, were generally less than that intended, i.e. 0.02, 0.69, 1.98, 3.35 and 6.04 days/week. Deviations from the intended number of accesses to supplement were mainly due to sheep not coming through to water on their allocated day of treatment access, although some instances were due to incorrect drafts. There was a non-linear response in growth rate to increased frequency of access to lupins with the growth rate response plateauing at similar to 3 actual accesses per week, corresponding to a growth rate of 72.5 g/head. day. This experiment has demonstrated the application of the remote drafting supplementation system for the first time under grazing conditions and with the drafter operated completely from solar power. The experiment demonstrates a growth response to increasing frequency of access to supplement and provides a starting point with which to begin to develop feeding strategies to achieve sheep weight-change targets.

Yield stagnation is a worldwide issue for lucerne breeding, and reasons for the yield plateau include emphasis on disease and pest resistance and not yield per se, and the broad-based synthetic approach to lucerne breeding which is generally used. In this study, an incomplete diallel was made between 50 lucerne clones with representatives from the 3 hypothetical heterotic groups, Medicago sativa subsp. falcata, dormant subsp. sativa, and non-dormant subsp. sativa. Male sterile clones were also included among the dormant group. The single crosses were compared in a subtropical environment at Gatton, Queensland, for yield and other relevant agronomic traits against the adapted synthetics Sequel (dormancy group 9), UQL-1 (group 7), and a highly non-dormant experimental synthetic (line B) derived by introgression of highly non-dormant Arabian germplasm into Sequel. The trial was conducted in a known low-disease-pressure site for Phytophthora root rot, and anthracnose was managed by regular application of prophylactic treatments. The best single cross outyielded Sequel and line B by 13% and 8%, respectively. In this environment, yield was very much influenced by the dormancy group of the test material, with group 9 material significantly outyielding more dormant material. General combining ability (GCA) effects were more important determinants of cumulative yields than specific combining ability (SCA) effects, with these effects being significantly greater than zero for only 4 of the 236 crosses tested over the 15-month period. Similarly, GCA effects were more important for determining autumn height and persistence. The research did identify a small number of clones with good GCA for yield per se, and it would appear that future work should focus on developing more narrow-based synthetics with 4–8 parents which have been selected on the basis of their GCA for yield per se. DNA markers would appear to have a role in selecting clones carrying multiple resistances, and in establishing marker pedigrees for high-yielding parental clones such as we have identified, which can be traced through subsequent generations of recurrent selection in cultivar improvement.

Remote drafting technology now available for sheep allows targeted supplementation of individuals within a grazing flock. This paper reports results of three experiments. Experiment 1 examined the weight change of Merino wethers allowed access to either lupin grain or whole cottonseed 0, 1, 2 or 7 days/week for 6 weeks. Experiment 2 examined the weight change of Merino wethers allowed access to either lupins or a sorghum + cottonseed meal (CSM) supplement 0, 2, 4 or 7 days/week for 8 weeks. Experiment 3 investigated the relationship between five allocations of trough space at the supplement self-feeders (5–50 cm/sheep) and the weight change of Merino wethers allowed access to lupins 1 day/week for 8 weeks. In all experiments, the Merino wethers had free access as a single group to drinking water and low quality hay in a large group pen and were allowed access to supplement once per day on their scheduled days of access. No water was available in the areas containing supplement, but one-way flow gates allowed animals to return to the group pen in their own time. There was a linear response in growth rate to increased frequency of access to lupins in Experiments 1 and 2, with each additional day of access increasing liveweight gain by 26 and 21 g/day, respectively. Similarly, the response to the sorghum + CSM supplement was linear, although significantly lower (P < 0.05), at 12 g/day. Providing access to whole cottonseed resulted in no significant change in growth rate compared with the control animals. In Experiment 3, decreasing trough space from 50 to 5 cm/sheep had no effect on sheep liveweight change. It was concluded that the relationships developed here, for growth response to increased frequency of access to lupins or a sorghum + CSM supplement, could be used to indicate the most appropriate frequency of access to supplement, through a remote drafting unit, to achieve sheep weight change targets. Also, that a trough space of 5 cm/sheep appears adequate in this supplementation system.

A series of 3-year experiments, spanning the period 1993-2006, evaluated the performance of commercially available cultivars and breeders' lines of perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea), brome grass (Bromus spp.) and phalaris (Phalaris aquatica) and the herbs, chicory (Cichorium intybus) and plantain (Plantago lanceolata) under irrigation in a subtropical environment. Measurements included annual and total dry matter (DM) yields, seasonal yields, persistence and resistance to rust in pure, nitrogen-fertilised swards.Summer-active tall fescue cultivars averaged around 50 (range 40-70) t/ha DM over 3 years, except at Mutdapilly where the average was 25 (range 11-34) t/ha DM. This was 30% more than perennial ryegrass cultivars (38 t/ha DM), with the prairie grasses (45 t /ha DM) intermediate between these extremes. About 45% of this total yield from all species occurred in the first year. The most productive cultivars were AU Triumph, Dovey, Quantum, Jesup and Jesup MaxP. Grasslands Matua and Atom produced the highest yields for brome grass and Tolosa, Fitzroy, Dobson, Bronsyn, Cannon and Quartet were the highest-yielding of the perennial ryegrasses, along with the hybrid ryegrass, Horizon. Tall fescue produced higher spring, summer and autumn yields than the perennial ryegrasses in this environment, with perennial ryegrasses superior in winter.Differences in persistence were of even greater magnitude; tall fescue cultivars were around twice as persistent as the perennial ryegrasses, while the bromes were less persistent than the perennial ryegrasses under a cut-and-carry regime.Incidence of crown rust was generally lower in tall fescue than in perennial ryegrass. However, the newer ryegrass cultivars and some experimental lines showed higher resistance than the older cultivars. Phalaris and the brome grasses were not infected by rust.First-year yields explained 67% of the variation in 3-year total yields and 50% of the variation in persistence after 3 years. The possibility of using detailed sampling in the first year and persistence over 3 years as a method of predicting cultivar performance is discussed.

In parts of Australia, sorghum grain is a cheaper alternative to other cereal grains but its use and nutritive value in sheep feeding systems is not well understood. The aim of this work was to compare growth and carcass characteristics for crossbred lambs consuming several simple, sorghum-based diets. The treatments were: ( 1) whole sorghum grain, ( 2) whole sorghum grain + urea and ammonium sulfate, ( 3) cracked sorghum grain + urea and ammonium sulfate, ( 4) expanded sorghum grain + urea and ammonium sulfate, ( 5) whole sorghum grain + cottonseed meal, and ( 6) whole sorghum grain + whole cottonseed. Nine lambs were slaughtered initially to provide baseline carcass data and the remaining 339 lambs were gradually introduced to the concentrate diets over 14 days before being fed concentrates and wheaten hay ad libitum for 41, 56 or 76 days.Neither cracking nor expanding whole sorghum grain with added non-protein nitrogen ( N) resulted in significantly ( P > 0.05) increased final liveweight, growth rates or carcass weights for lambs, or in decreased days on feed to reach 18-kg carcass weight, although carcass fat depth was significantly ( P < 0.05) increased compared with the whole sorghum plus non-protein N diet. However, expanding sorghum grain significantly ( P < 0.05) reduced faecal starch concentrations compared with whole or cracked sorghum diets with added non-protein N ( 79 v. 189 g/kg DM after 59 days on feed). Lambs fed whole sorghum grain without an additional N source had significantly ( P < 0.05) lower concentrate intake and required significantly ( P < 0.05) more days on feed to reach a carcass weight of 18 kg than for all diets containing added N. These lambs also had significantly ( P < 0.05) lower carcass weight and fat depth than for lambs consuming whole sorghum plus true protein diets. Substituting sources of true protein ( cottonseed meal and whole cottonseed) for nonprotein N ( urea and ammonium sulfate) did not significantly ( P > 0.05) affect concentrate intakes or carcass weights of lambs although carcass fat depth was significantly ( P < 0.05) increased and the days to reach 18-kg carcass weight were significantly ( P < 0.05) decreased for the whole sorghum plus cottonseed meal diet.In conclusion, processing sorghum grain by cracking or expanding did not significantly improve lamb performance. While providing an additional N source with sorghum grain significantly increased lamb performance, there was no benefit in final carcass weight of lambs from substituting sources of true protein for non-protein N.

Grain feeding low bodyweight, cast-for-age (CFA) sheep from pastoral areas of eastern Australia at the end of the growing season can enable critical carcass weight grades to be achieved and thus yield better economic returns. The aim of this work was to compare growth and carcass characteristics for CFA Merino ewes consuming either simple diets based on whole sorghum grain or commercial feed pellets. The experiment also compared various sources of additional nitrogen (N) for inclusion in sorghum diets and evaluated several introductory regimes. Seventeen ewes were killed initially to provide baseline carcass data and the remaining 301 ewes were gradually introduced to the concentrate diets over 14 days before being fed concentrates and wheaten hay ad libitum for 33 or 68 days. Concentrate treatments were: (i) commercial feed pellets, ( ii) sorghum mix (SM; whole sorghum grain, limestone, salt and molasses) + urea and ammonium sulfate (SMU), (iii) SMU + whole cottonseed at 286 g/kg of concentrate dry matter (DM), (iv) SM + cottonseed meal at 139 g/kg of concentrate DM, ( v) SMU + virginiamycin ( 20 mg/ kg of concentrate) for the first 21 days of feeding, and ( vi) whole cottonseed gradually replaced by SMU over the first 14 days of feeding.The target carcass weight of 18 kg was achieved after only 33 days on feed for the pellets and the SM + cottonseed meal diet. All other whole grain sorghum diets required between 33 and 68 days on feed to achieve the target carcass weight. Concentrates based on whole sorghum grain generally produced significantly ( P < 0.05) lower carcass weight and fat score than pellets and this may have been linked to the significantly ( P < 0.05) higher faecal starch concentrations for ewes consuming sorghum-based diets ( 270 v. 72 g/kg DM on day 51 of feeding for sorghum-based diets and pellets, respectively). Source of N in whole grain sorghum rations and special introductory regimes had no significant ( P > 0.05) effects on carcass weight or fat score of ewes with the exception of carcass weight for SMU + whole cottonseed being significantly lower than SM + cottonseed meal at day 33.Ewes finished on all diets produced acceptable carcasses although muscle pH was high in all ewe carcasses ( average 5.8 and 5.7 at 33 and 68 days, respectively). There were no significant ( P > 0.05) differences between diets in concentrate DM intake, rumen fluid pH, meat colour score, fat colour score, eye muscle area, meat pH or meat temperature.

In the subtropics of Australia, irrigated temperate species are the key to reliable cool season feed on dairy farms. Persistence of perennial species is a major limitation to achieving reliable production from irrigated areas and yearly sowings of annual ryegrasses have replaced them as the most productive cool season forage production system in the subtropics. This series of experiments evaluated the yield, and resistance to rust damage, of commercially available cultivars and breeders' lines of annually sown ryegrasses (Lolium multiflorum, L. rigidum, L. x boucheanum and L perenne) in pure, nitrogen-fertilised swards under irrigation in the subtropics over a 22-year period. Barberia and Aristocrat 2 were the most adapted cultivars for subtropical conditions, producing high yields (119 and 114% of mean yield, respectively) and demonstrating the least rust damage. Newer selections from New Zealand, South African, United States of America and European breeding programs are performing better under subtropical conditions than older cultivars, particularly if a component of the selection process has been conducted in that environment. Cultivars such as Passerei Plus, Crusader, Hulk, Status and Warrior are examples of this process, producing between 105 and 115% of mean yield. Yields of annual ryegrass cultivars, which have been available or still are available for sale in Australia, ranged from 14-30 t/ha DM, depending on cultivar, site and seasonal conditions. Yields were lower at the site, which had inferior soil structure and drainage. Up to 50% of yield was produced in the 3 winter months. There was a trend towards improved yields and better tolerance of crown rust from experimental lines in the subtropics, as breeders strive for wider adaptation. Around 70% of the variation in total yield of annual ryegrass and 50 and 60% of the variation in winter and spring yield, respectively, were significantly explained by cultivar, site and climatic variables in autumn, winter and spring. While level of rust damage had no effect on total or seasonal yields, it affected the amount of green leaf available in spring. Under subtropical conditions, winter, spring and overall (autumn to mid-summer) temperatures influenced the- development of rust, which along with cultivar, accounted for 46% of the variation in rust damage. Cultivars showed a range of adaptation, with some performing well only under adverse conditions, some being well adapted to all conditions and some which performed well only under favoured conditions. Cultivars with high winter yields were most suited to subtropical conditions and included Aristocrat 2 (now released as CM 108), Barberia, Warrior, Crusader, Status, Passerei Plus and Hulk. Short growing season types such as Winter Star and T Rex performed well in winter but achieved lower total production, and long season cultivars such as Flanker rarely achieved their potential because of unfavourable conditions in late summer.

The effect of interspecific heterosis in crosses between Medicago sativa subsp. sativa and M. sativa subsp. falcata was assessed. Three sativa and 3 falcata plants were crossed in a diallel design. Progeny dry matter yield and natural plant height were assessed in a replicated field experiment at Gatton, Queensland. Yield data were analysed using the method of residual maximum likelihood (REML) and Griffing’s model 1. There were significant differences between the reciprocal, general combining ability (GCA), and specific combining ability (SCA) effects. As expected, S1 populations were lower yielding than their respective intraspecific cross and falcata × falcata crosses were significantly lower yielding than sativa × sativa crosses. Some of the interspecific crosses indicated substantial SCA effects, yielding at least as well as the best sativa × sativa crosses. We have demonstrated the potential usefulness of unselected M. sativa subsp. falcata as a heterotic group in the improvement of yield in northern Australian adapted lucerne material, and discuss how it could be incorporated into future breeding to overcome the yield stagnation currently being experienced in Australian programs.

Dairy farms in subtropical Australia use irrigated, annually sown short-term ryegrass (Lolium multiflorum) or mixtures of short-term ryegrass and white (Trifolium repens) and Persian (shaftal) (T. resupinatum) clover during the winter–spring period in all-year-round milk production systems. A series of small plot cutting experiments was conducted in 3 dairying regions (tropical upland, north Queensland, and subtropical southeast Queensland and northern New South Wales) to determine the most effective rate and frequency of application of nitrogen (N) fertiliser. The experiments were not grazed, nor was harvested material returned to the plots, after sampling. Rates up to 100 kg N/ha.month (as urea or calcium ammonium nitrate) and up to 200 kg N/ha every 2 months (as urea) were applied to pure stands of ryegrass in 1991. In 1993 and 1994, urea, at rates up to 150 kg N/ha.month and to 200 kg N/ha every 2 months, was applied to pure stands of ryegrass; urea, at rates up to 50 kg N/ha.month, was also applied to ryegrass–clover mixtures. The results indicate that applications of 50–85 kg N/ha.month can be recommended for short-term ryegrass pastures throughout the subtropics and tropical uplands of eastern Australia, irrespective of soil type. At this rate, dry matter yields will reach about 90% of their potential, forage nitrogen concentration will be increased, there is minimal risk to stock from nitrate poisoning and there will be no substantial increase in soil N. The rate of N for ryegrass–clover pastures is slightly higher than for pure ryegrass but, at these rates, the clover component will be suppressed. However, increased ryegrass yields and higher forage nitrogen concentrations will compensate for the reduced clover component. At application rates up to 100 kg N/ha.month, build-up of NO3–-N and NH4+-N in soil was generally restricted to the surface layers (0–20 cm) of the soil, but there was a substantial increase throughout the soil profile at 150 kg N/ha.month. The build-up of NO3–-N and NH4+-N was greater and was found at lower rates on the lighter soil compared with heavy clays. Generally, most of the soil N was in the NO3–-N form and most was in the top 20 cm.

A study was conducted to determine growth responses in hoggets grazing drought affected Mitchell grass pastures in western Queensland, and fed different supplements. Eighteen paddocks, each of 6 ha, were stratified into 3 replicates. These were severely drought affected, dry, rank pastures consisting mainly of stalk with some dry leaf (7.4 MJ metabolisable energy (ME)/kg; 4.3% crude protein (CP)) and approximately 1.75 t DM/ha. One hundred and eight hogget Merino wethers (approximately 18 months old), weighing 39 kg (s.d. ± 5.0), were stratified by initial liveweight and randomly allocated to paddocks. The nutrient composition of grains was aimed to supply 10 MJ ME/d as the upper level of supplementation for each treatment. Supplement treatments (ME (MJ/kg DM), CP (%) and planned maximum supplement levels (g/h/d)), were as follows: 1) corn (12.3, 9.1, 815), 2) lupins (11.5, 31.1, 870), 3) cottonseed (12.9, 20.4, 775), 4) sorghum (12.2, 8.1, 820); 5), sorghum (12.2, 8.1, 820). All supplements were fed on the ground except for sorghum in treatment 5, which was fed in troughs. Treatment 6 was dry pasture only (control). The corn and sorghum were treated with urea (0.8%) and sulphate of ammonia (0.2%) in water to increase their CP to 12%. Sheep were weighed and gradually introduced to the grains in the paddock commencing 28 October 2003. The grain was fed daily in increasing amounts during the first 14 days, and then increased every second day. Amounts of supplement offered were adjusted based on amount left uneaten. Animals were weighed prior to feeding each week over a 10-week period, with final weights recorded on 5 January 2004. Linear growth rates (ADG) were estimated by fitted spline analysis.

The experiment started in March 2002 with a 1-week adaptation, and an 8-week observation, period. Forty-two Holstein-Friesian cows in early/mid-lactation were stratified and randomly allocated to 6 groups of 7 cows. Each group was offered a SGM (11 kg DM/cow/day) formulated to contain CP of 10, 12, 14, 16.5, 19 or 21% DM. This was achieved by substituting cottonseed meal (CSM) and urea for grain. The SGM consisted of maize silage, barley grain, CSM and urea (4.3, 3.6-6.2, 0.56-2.8 and 0-0.1 kg DM/head/day, respectively). The cows were fed on a shaded feed-pad during the day, and during the evening and night, they grazed rhodes grass (Chloris gayana cv. Callide) pasture, with a fresh pasture strip offered each day. A regression model of parallel smooth curves with additional linear trends for the CP% of each SGM best represented 4% fat corrected milk yield (FCM) (P=0.06), with the slope for 10% CP being different to those for 14, 16.5 and 21% (Figure 1). Similar analyses fitting cubic smoothing splines for the effect of the CP% of SGM on FCM for each week showed that much of the difference in weeks 3- 9 could be accounted for by fitting parallel smoothed curves to each week's data. Quadratic regressions that best reflected the curves were then fitted for each week (P<0.001) (Figure 2).