Significant features of the epidemiology of equine influenza in New South Wales, Australia, 2007

Equine influenza (EI) was first diagnosed in the Australian horse population on 24 August 2007 at Centennial Park Equestrian Centre (CPEC) in Sydney, New South Wales (NSW), Australia. By then, the virus had already spread to many properties in NSW and southern Queensland. The outbreak in NSW affected approximately 6000 premises populated by approximately 47,000 horses. Analyses undertaken by the epidemiology section, a distinct unit within the planning section of the State Disease Control Headquarters, included the attack risk on affected properties, the level of under-reporting of affected properties and a risk assessment of the movement of horses out of the Special Restricted Area. We describe the epidemiological features and the lessons learned from the outbreak in NSW.     

Predictive modeling of spatial patterns of soil nutrients related to fertility islands

In arid shrublands, soil resources are patchily distributed around shrub canopies, forming well-studied “islands of fertility.” While soil nutrient patterns have previously been characterized quantitatively, we develop a predictive model that explicitly considers the distance from shrubs of varying canopy sizes. In 1-ha macroplots in both the Sonoran and Mojave Deserts, we used Plant Root Simulator? probes to measure nutrient availability along transects extending north and south from creosote bushes (Larrea tridentata). We modeled the decline of nutrients with distance from focal shrubs using hierarchical mixed models that included the effects of transect direction and shrub canopy size. Of the nutrients considered, nitrogen and potassium had the strongest response to distance from focal shrubs. In the Sonora, both depended on canopy size and had different patterns to the north versus the south. In the Mojave, potassium depended on size and direction, but nitrogen only on canopy size. We used the fitted model equations and the location and canopy size of all Larrea shrubs within the macroplots to estimate nutrient concentrations at a 20 cm resolution. This produced maps showing nutrient “hotspots” centered on Larrea. Our models predicted up to 60 % of the variation in nutrient availability the following growing season. Our models efficiently used a moderate number of sample locations to predict nutrient concentrations over a large area, given easily measured values of shrub size and location. Our method can be applied to many systems with patchily distributed resources focused around major structural landscape features.     

Growth, feed efficiency and carcass composition of finishing Friesian steers fed the beta-adrenergic agonist L-644,969

The beta-adrenergic agonist L-644,969 was evaluated to determine its effects on growth performance and carcass composition of Friesian steers. L-644,969 is the R,R isomer of 6-amino [[(1-methyl-3-phenylpropyl) amino] methyl]-3-pyridine methanol dihydrochloride. Four groups of 18 steers, averaging 380 kg body weight, were individually given ad libitum access to a pelleted concentrate diet that contained either 0, .25, 1.0 or 4.0 ppm L-644,969 for the final 12 wk of the finishing period. Live weight gain was not affected by L-644,969, but feed consumption was linearly reduced (5.5, 6.3 and 15.7%; P less than .01) and feed conversion efficiency was linearly increased (16, 25 and 31%; P less than .01) relative to unmedicated controls, respectively. In addition, L-644,969 quadratically increased carcass weight (3.7, 9.3 and 8.5%; P less than .01) and dressing percentage (2.7, 7.9 and 7.9%; P less than .001). The proportion of trimmed fat in the carcass was quadratically reduced (14.5, 29 and 36%; P less than .001) and yield of lean meat quadratically increased (6.7, 13 and 15.6%; P less than .001). beta-adrenergic agonist treatment altered the distribution of lean meat such that a greater (P less than .001) proportion of the total lean was in the hind portion of carcasses from treated animals. Based on these findings, we suggest that L-644,969 may have utility as an agent to improve efficiency of production of lean beef.     

Multielement isotope analysis of bovine muscle for determination of international geographical origin of meat

Multielemental (C, N, H, S) stable isotope ratio analysis was used as an analytical tool to verify the geographical origin of beef from several European and non-European countries. Beef samples were collected from nine different countries, and the (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S ratios of defatted beef were measured using isotope ratio mass spectrometry (IRMS). There were highly significant differences in the mean isotopic values of the beef from different countries. The results of discriminant analysis showed that the four isotope ratios were significant for the discrimination of geographical origin and that 84.9% of the samples were correctly assigned to the country of origin (82.2% when cross-validated). Beef was also classified according to geographical origin when additional information on different feeding regimens used in Ireland was included, with 85.0% of the samples correctly allocated and 82.9% cross-validated using the isotopic signatures. All of the Irish beef samples verifiable as pasture-fed beef were correctly classified and then cross-validated.     

The effects of defoliating grass in winter or spring on herbage yields and ensilage characteristics

Under Irish conditions, the digestibility in May of grass managed for silage production is sometimes lower than expected. In each of two successive years, replicate field plots were established to examine the effects of three defoliation heights (uncut or cut to a stubble height of 10 or 5 cm) applied in winter and/or spring on herbage yields harvested in May and again in July, and on chemical composition and conservation characteristics associated with first‐cut silage. Swards that were not defoliated in December or March had a dry‐matter (DM) yield and in vitro DM digestibility (DMD) in mid‐May of 6597 kg ha^?1 and 736 g kg^?1, respectively, in Year 1, and corresponding values of 7338 kg ha^?1 and 771 g kg^?1 in Year 2. Defoliating swards to 5 cm in December reduced (P < 0·001) May DM yields compared to swards that were not defoliated in both December and March, while herbage DMD in May increased (P < 0·001) when defoliated in December or March. There were no clear effects of defoliation height or its timing on herbage ensilability or resultant conservation efficiency characteristics. The effects of defoliation on July yield were the reverse of those observed for May, while the total yield of the December and March defoliations plus the two silage harvests increased as defoliation height was lowered in Year 2 only. It is concluded that defoliation in winter and/or spring can increase herbage digestibility but will likely reduce DM yields in May.     

Multiple use of water and water productivity of communal small dams in the Limpopo Basin, Zimbabwe

The history of dam construction in Zimbabwe dates back to the 1920s and since then over 7,000 small dams have been constructed countrywide. Small dams are multipurpose structures used for improving rural livelihoods. The multipurpose nature of these dams has largely gone unquantified in terms of importance of the uses to the community and influence of management practises. The current study made use of a questionnaire among small dam users, key informant interviews, secondary data and observation on four communal dams in the Limpopo basin to establish the uses, volume of water abstracted and water productivity for some uses and the interrelationship between various organisations and the community in the management of small dams. Uses on all dams in order of importance were livestock watering, domestic use, irrigation, fishing, brick making, and collection of reeds used for roofing. Livestock consume on average over 70% of water for consumptive uses. Water productivity in terms of yield per volume unit of water used ranged from 0.025 kg m^?3 for vegetables to 7,575 kg m^?3 for bricks, and monetary values per volume unit of water used were Z$ 389,434 m^?3 for brick making and Z$ 1,874 m^?3 for irrigation. Traditional leadership and the community are pivotal in the management of the small dams, with some organisations giving technical, financial and input assistance. The management and conservation of small dams needs to be well coordinated between the communities, NGOs and government if the full benefits of these national resources are to be realised in the long term.     

Intake, performance and carcass characteristics of beef cattle offered diets based on whole-crop wheat or forage maize relative to grass silage or ad libitum concentrates

Seventy beef steers, mean initial live-weight 424 (S.D. 33.0) kg, were blocked by live-weight and breed and allocated to one of 5 dietary treatments in a randomised complete block design. Treatments, including supplementation with 3 kg concentrates/head/day, were grass silage (GS), maize silage (MS), fermented whole-crop wheat (FWCW), urea-treated, processed whole-crop wheat (UPWCW), and ad libitum concentrates supplemented with 5 kg grass silage/head/day (ALC). The grain in urea-treated, processed whole-crop wheat (WCW) was cracked and the crop ensiled with a urea plus urease-based additive. The mean dry matter (DM) of the grass silage, maize silage, fermented WCW and urea-treated, processed WCW was 174, 315, 404 and 716 g/kg, respectively. Total DM intake and carcass growth were lowest for GS (P < 0.001). Relative to ALC, feed conversion efficiency (FCE) (P < 0.05), live-weight gain (P < 0.05), carcass-weight gain (P < 0.01) and kill-out rate (P < 0.05) were lower for GS, FWCW and UPWCW. The MS had a better FCE than the UPWCW (P < 0.001) or the FWCW (P < 0.05). Plasma urea concentration was lowest for MS and highest for UPWCW (P < 0.001). Animals offered the GS treatment had the most yellow fat (higher (P < 0.05) ‘b’ value) and those offered UPWCW had the whitest fat (lower (P < 0.01) ‘b’ value). It is concluded that MS, FWCW and UPWCW supported superior levels of growth by cattle compared to GS (in vitro DM digestibility 674 g/kg). There was no animal productivity advantage with UPWCW compared to FWCW.     

Feeding value for finishing beef steers of wheat grain conserved by different techniques

The objective was to determine the feeding value of high moisture grain as an alternative to dry grain for finishing beef cattle. Winter wheat grain was harvested sequentially for rolling, acid treatment and ensilage (ER; 705 g dry matter (DM)/kg), urea whole grain treatment and anaerobic storage (UN; 746 g DM/kg) and whole grain propionic acid treatment and aerobic storage (rolled before feeding; PR; 849 g DM/kg). Friesian steers (n = 120; mean starting live-weight 518 kg) were allocated on a live-weight basis to 12 replicate blocks and then randomly assigned from within blocks to ten treatments. Treatments were grass silage offered ad libitum together with (i) no wheat, (ii–iv) PR at 3 or 6 kg/head daily, or ad libitum, (v–vii) UN at equivalent DM allowances to (ii) and (iii) above, or ad libitum, (viii–x) ER at equivalent DM allowances to (ii) and (iii) above, or ad libitum. Mean daily live-weight gains were 852 (ER), 726 (UN) and 855 g (PR) (s.e. = 65.5; P < 0.05) with corresponding values for carcass gain of 522, 425 and 528 g (s.e. = 35.6; P < 0.001) and daily silage DM intakes of 3.5, 4.0 and 3.6 kg (s.e. = 0.15; P < 0.001). Wheat DM intake when offered ad libitum was 7.8, 8.3 and 8.2 kg (s.e. = 0.10; P < 0.05) for ER, UN and PR, respectively. The content of apparently undigested whole grains and starch in faeces was higher (P < 0.001) for UN than for ER and PR, particularly at higher rates of wheat ingestion. It is concluded that ER treatment of wheat grain can be an acceptable alternative to the more traditional PR and superior to the UN treatment in the diets of finishing beef cattle.