Appraisal of environmental profiles of pasture-based milk production: a case study of dairy farms in the Waikato region,New Zealand

Purpose

Dairying is a relatively intensive livestock production system and contributes to a range of environmental impacts. In the southern hemisphere, dairy farming systems are based mainly on outdoor grazing of permanent pastures. The objectives of this study were to (i) assess environmental profiles and (ii) to identify environmental hotspots in a pasture-based dairy farming system.

Methods

A cradle-to-farm gate life cycle assessment of 53 dairy farms in the Waikato region, New Zealand, was carried out, using 1 kg of fat- and protein-corrected milk as the functional unit. Twelve environmental impact categories were assessed: climate change (CC), ozone depletion potential (ODP), cancer effects (Cancer), non-cancer effects (non-cancer), particulate matter (PM), ionizing radiation (IR), photochemical ozone formation potential (POFP), acidification potential (AP), terrestrial eutrophication potential (TEP), freshwater eutrophication potential (FEP), marine eutrophication potential (MEP) and ecotoxicity for aquatic freshwater (Ecotox). Contribution and sensitivity analyses were performed to determine key hotspots and investigate potential changes in results due to methodological choices.

Results and discussion

The on-farm stage contributed >50 % of the total result for 7 out of 12 indicators (CC, Non-cancer, PM, POFP, AP, TEP, MEP). The off-farm rearing of replacement animals contributed 11–20 % to the total result for all indicators. The production of brought-in (from off-farm) feeds for use on the dairy farms contributed >10 % to the indicator results for Non-cancer (25 %), FEP (15 %), MEP (12 %) and Ecotox (19 %). The manufacturing of agrichemicals for use on the dairy farms contributed >10 % to the indicator results for ODP (26 %), Cancer (26 %), PM (19 %), IR (46 %), FEP (25 %) and Ecotox (42 %). The transportation of off-farm inputs for use on the dairy farms contributed >10 % to the impacts on ODP (15 %), IR (21 %) and POFP (11 %). Sensitivity analysis demonstrated the influence of choices associated with data sources, inventories and impact assessment models on the results.

Conclusions

The off-farm activities together contributed >50 % to 5 out of 12 impact indicator results, >45 % to a further two impact indicator results and 32 % of the CC result. Therefore, environmental improvement options should focus on both on-farm and off-farm activities. A focus on just one impact category (such as CC) risks ignoring the environmental hotspots that are revealed in a more comprehensive environmental assessment.

     

Too late for the midwife toad: stress, variability and Hsp90.

In the 1940s and 1950s, Waddington put forward his theories of canalization and genetic assimilation. These provided a genetic basis to account for the inheritance of some apparently 'acquired' characters. Rutherford and Lindquist have now provided a molecular framework for these theories. Their results are also relevant to observations from the 1950s concerning homozygosity and variability, with a bearing on current views concerning the use of inbred strains.     

Genomic imprinting of the insulin-like growth factor 2 gene in sheep

A number of genes in the human and mouse genomes are subject to genomic imprinting, with selective inactivation of one allele of a gene in a parent-of-origin specific manner. One of the first imprinted genes identified was the Insulin-like Growth Factor 2 gene (IGF2), which promotes growth of the fetus and is expressed from only the paternal allele in most tissues in both the mouse and human. The aim of this study was to establish the imprinting status of IGF2 in sheep (Ovis aries). Sheep provide an interesting model to study imprinting, owing to differences in their placental development and the fact that they have been subject to strong artificial selection for various production traits. We report the identification of a length polymorphism in the transcribed 3′-untranslated region of the ovine IGF2 gene. This polymorphism was used to map IGF2 to sheep Chromosome (Chr) 21 and demonstrate that IGF2 is indeed imprinted in sheep, being expressed from the paternal allele. We also report that the developmental switch from imprinted IGF2 expression in the fetal liver to biallelic IGF2 expression in the adult liver, which occurs in the human but not mouse, also occurs in sheep. Differences in male- and female-specific recombination values reported around the IGF2 locus in the human were also observed around the ovine IGF2 locus. The techniques developed in this study will enable the imprinting status of IGF2 to be assessed in a variety of tissues and stages of development in normal sheep. Received: 3 October 1998 / Accepted 29 January 1999     

Schistosoma mansoni: schistosomulicidal activity of macrophages isolated from liver granulomas of infected mice

Mice infected with Schistosoma mansoni develop T cell-mediated granulomatous reactions around disseminated parasite eggs. In this study, granuloma-derived leucocytes have been examined for schistosomulicidal capacity by the use of in vitro cytotoxicity assays. Adherent macrophages, that were shown by electron microscopy to exhibit no gross morphological abnormalities, were unable to mediate significant mortality in the absence of serum factors. When cocultured with immune serum and complement, however, these cells killed +/- 26% of the larvae at a cell:target ratio of 5000:1. In contrast, granuloma-derived cell populations that were enriched for eosinophils (50-70% eosinophil content) showed only minimal cytotoxic potential. This may be related to observed structural changes in the eosinophil lysosomal granules, or perhaps to blocking of the cell-surface receptors by immune complexes. It is concluded that granuloma macrophages, activated by egg antigen-sensitised T lymphocytes, may serve as effector cells in immunity to schistosomules.