Marking to weaning production aspects of lambs provided with NSAID analgesia compared with lambs receiving no analgesia at the time of elastrator ring marking

The provision of analgesia at the time of marking has been adopted by the Australian sheep industry, but data on production benefits are lacking. In the current study, alternate lambs were provided with either meloxicam (non‐steroidal anti‐inflammatory drug [NSAID], n = 781) or no analgesia (NONE, n = 822) at the time of ring castration and tail docking. Six distinct management groups of lambs were studied. Lambs were weighed immediately before marking and then again at weaning. There was no significant effect of treatment on average daily gain between marking and weaning in cross‐bred lambs. In Merino lambs, average daily gain was 5 g/day lower (P < 0.005) in lambs receiving NSAID, but this may not be biologically significant. Lamb losses were significantly (P < 0.05) lower in the NSAID group (1.1%) than in the NONE group (2.7%). This observation is worth validating in larger studies, particularly considering that lamb mortality is a significant cost to production and welfare concern.     

Long-term heathland restoration on former grassland: The results of a 17-year experiment

European lowland heaths have declined by up to 80% due to land use change and lack of management. There has been considerable research into the restoration of this threatened habitat. However, long-term outcomes of restoration are poorly understood, especially in situations where past agricultural land use imposes severe constraints on community re-assembly. In 1989 a large-scale experiment was established to examine the effectiveness of five treatments to restore heathland on formerly productive grassland: (i) natural regeneration; (ii) herbicide application to facilitate regeneration; (iii) cultivation and application of seed-rich heathland vegetation; (iv) soil removal and incorporation of heathland topsoil; and (v) heathland translocation. After 17 years the pH of the unamended agricultural soil remained significantly higher than that of the adjacent heathland. All treatments showed different trajectories of vegetation change in the long-term. Natural colonisation by heathland species was slow due to seed limitation, resulting in formation of an acid grassland community. Heathland community assembly was not facilitated by destruction of the initial grassland with herbicide. Incorporation of topsoil had an intermediate effect on pH reduction. This may explain the subsequent failure of the plant community to assemble in the anticipated proportions, and the dominance of leguminous scrub species (Ulex spp.). Turf translocation was effective in reducing pH to the required range and restoring the heathland community in the long-term. However, this technique should only be considered as a means of ‘rescue’ when habitat destruction is otherwise unavoidable. The only practical and sustainable means of increasing heathland extent on former farmland is the application of seed-bearing vegetation cut as part of routine management. However, this technique needs refining in order to establish the full range of characteristic heathland species.     

Equine neural angiostrongylosis

Verminous encephalomyelitis due to Angiostrongylus cantonensis larvae was diagnosed in 2 foals at necropsy. The principal clinical feature was tetraparesis, although history and neurological examination revealed progressive and multifocal neurological disease. At presentation, a tentative diagnosis of parasitic larval migration involving the central nervous system (CNS), presumably due to Strongylus vulgaris, was proposed. Dissection of the spinal cord in one case resulted in recovery of intact larvae of both sexes of A. cantonensis. In both foals, histopathology of the brain and spinal cord revealed nematode sections which were consistent with A. cantonensis larvae.     

Bovine Mastitis: A Survey of Ontario Dairy Producers, 1978

A survey to assess the knowledge and perception regarding mastitis of 1200 randomly selected Ontario dairy producers was conducted using a mailed questionnaire. Other data were provided by the Ontario Milk Marketing Board and the Dairy Herd Improvement Association.

In general, producers were less aware of subclinical than clinical mastitis and did not appreciate the losses in production associated with it. Approximately 40% of producers were not familiar with mastitis in its subclinical form.

Many producers have not adopted practices that have been advocated for the integrated control of mastitis. For example, 35.5% of producers surveyed used single service paper towels and 38% regularly used teat dips and dry cow antibiotic therapy.

     

Effect of high frequency surface and subsurface drip irrigation on root distribution of sweet corn

Summary Characterization of root growth and distribution is fundamental in explaining crop responses to irrigation and in determining appropriate management of irrigation systems, particularly with drip systems since it is widely believed that drip irrigation may limit the extent of root development. An experiment was conducted to study root distribution of sweet corn grown under high frequency surface (S) and subsurface (SS) drip irrigation, fertilized daily through drip systems at three phosphorus levels of P₀ (no injected P), P₁ (P injected at 67 kg/ha) and P₂ (P injected at 134 kg/ha). Root sampling at the end of the growing season indicated that: (1) Root extension continued at depths in excess of 2 m in both the surface and subsurface drip at all P levels. (2) The greatest differences between SS and S treatments were observed in the top 45 cm depth. Higher root length density was observed in the surface 30 cm in S plots while the sweet corn in the SS plots had greater root length density than S plots below 30 cm, and (3) the greater root length density in the SS irrigated sweet corn was not reflected in a similar increase in total above-ground dry matter.This project was partially supported by a grant from BARD Project no I-1116-86     

Relationship Between Six Years of Corn Yields and Terrain Attributes

Crop yield, soil properties, and erosion are strongly related to terrain attributes. The objectives of our study were to examine the relationship between six years of corn (Zea mays L.) yield data and relative elevation, slope, and curvature, and to develop a linear regression model to describe the spatial patterns of corn yield for a 16 ha field in central Iowa, USA. Corn grain yield was measured in six crop years, and relative elevation was measured using a kinematic global positioning system. Slope and curvature were then determined using digital terrain analysis. Our data showed that in the four years with less than normal growing season precipitation, corn yield was negatively correlated with relative elevation, slope, and curvature. In the two years with greater than normal precipitation, yield was positively correlated with relative elevation and slope. A multiple linear regression model based on relative elevation, slope, and curvature was developed that predicted 78% of the spatial variability of the average yield of the transect plots for the four dry years. This model also adequately identified the spatial patterns within the entire field for yield monitor data from 1997, which was one of the dry years. The relationship between terrain attributes and corn yield spatial patterns may provide opportunities for implementing site-specific management.     

Selenium accumulation in selected vegetables

Greenhouse experiments were conducted to determine selenium (Se) uptake by sulfur‐accumulating vegetables. Cabbage (Brassica oleracea var. capitata), broccoli (Brassica oleracea var. botrytis), Swiss chard (Beta vulgaris var. cicla) and collards (Brassica Oleracea var. acephda) were grown in a soil mix to which 4.5 mg of selenate or selenite had been added per kg of soil. Plants were grown to maturity, separated into plant organs, and the tissues analyzed for Se and sulfate (SO₄). Vegetables grown in selenate laden soil significantly (P<0.05) accumulated higher concentrations of Se than plants grown in selenite laden soil. The highest concentrations of Se and SO₄ were found in the broccoli floret and vegetable leaf tissues.

A second greenhouse experiment examined the uptake of Se and SO₄ in broccoli (Brassica oleracea var. botrytis) grown hydroponically with increasing Se concentrations. Treatments consisted of three Se concentrations (2, 6, and 15 mg of selenate, added as Na₂SeO₄/L to a synthetic water solution, including SO₄). Solution samples were taken weekly and analyzed for Se and SO₄. The removal or uptake of both Se and SO₄ by broccoli was positively related (P<0.05) with time at each Se concentration. After 6 weeks in Se treatments, uptake responses of Se and SO₄ were significantly different (P<0.05) based apon analyses of covariance. Composite leave samples were also taken from the broccoli plants and analyzed for Se and SO₄. Selenium concentrations were negatively correlated (P<0.08) with SO₄ concentrations in the leaf tissue.     

Variability of light interception and radiation use efficiency in maize and soybean

Variability of light interception and its derivatives are poorly understood at the field-scale in maize (Zea mays L.) and soybean [Glyine max (L.) Merr.]. Quantifying variability can provide reliable estimates of field-scale processes and reliable methodology. A field study was conducted during the 2005 growing season in a 31 ha maize and 23 ha soybean field rotated annually near Ames, IA to measure variability of cumulatively intercepted photosynthetically active radiation (CI-PAR) and radiation use efficiency (RUE) by deploying eight line quantum sensors in each field. Cumulative mean PAR interception for soybean was 575 MJ m⁻² ending on day of the year (DOY) 249 compared with 687 MJ m⁻² in maize ending on DOY 244. Soybean standard error (s_X) for a single sensor was 4.48% and with six sensors was 1.83% of the final CI-PAR. Maize s_X for a single sensor was 5.29% and with eight sensors was 1.87% of the final CI-PAR. Crop biomass was quantified weekly by collecting four 1 m² samples. Soybean RUE using all sensors was 1.44 ± 0.06 g MJ PAR⁻¹. The highest CI-PAR from a single sensor had RUE of 1.32 and the lowest was 1.55 g MJ PAR⁻¹. Maize RUE using all sensors was 3.35 ± 0.09. The highest CI-PAR from a single sensor had RUE of 2.87 and the lowest was 3.70 g MJ PAR⁻¹. Reliable transmitted PAR and RUE estimates are obtainable at the field-scale in maize and soybean with four and three sensors, respectively, assuming that crop biomass is accurately measured.