Animal production in a sustainable agriculture

This paper discusses the role of animal production systems in a sustainable society; sustainability problems within animal production systems; and four measures for the improvement of the contribution to societal sustainability from animal production. Substantial potentials for improvements are identified that were not previously known. The methodological basis is multi-criteria multi-level analysis within integrated assessment where elements in Impredicative Loop Analysis are integrated with management tools in Swedish agriculture and forestry developed during thousands of years, during which the well-being of the Swedish society and its economic and military power were functions of the land-use skill. The issue—the sustainability footprint of global animal production—is complex and available data are limited. The Swedish case is used as a starting point for an analysis of international relevance. Data from FAO and OECD support the relevance of extrapolating results from the Swedish case to level. The four measures are (i) decrease the consumption of chicken meat in developed nations with 2.6 kg per capita and year; (ii) develop the capacity of ruminants to produce high-quality food from otherwise marginal agroecosystems; (iii) improve milk production per cow with a factor four on global level; and (iv) increase feeding efficiency in milk production globally would substantially improve the societal contribution in terms of increased food supply and decreased pressure on land. The impact of measures (i), (iii) and (iv) on increased global food security was estimated to in total 1.8 billion people in terms of protein supply and a decreased pressure on agricultural land of 217 million ha, of which 41 relate to tropical forests. The 41 million ha of tropical land are due to a decreased demand on soymeal, where this represents more than a halving of total area now used for the production of soymeal. These impacts are of the character either or. The quality of the measures is as first-time estimates, supporting choices of where to direct further efforts in analysis. Two areas were identified as critical for achieving this potential: Feeding strategies to dairy cows as well as methods commonly used to evaluate the sustainability contribution of animal production needs adjustment, so that they comply with the “laws” of diminishing returns, Liebig’s “law” of the minimum and Shelford’s “law” of tolerance, that is, in agreement with well-known principles for efficient natural resource management and the priorities of UN Millennium Development Goals. If not, global food security is at risk.     

Song type variants and aggressive context

We asked whether switching among song type variants functions as a graded signal of aggression in song sparrows (Melospiza melodia). Song type variants are different versions of a given song type and are defined by much smaller acoustic differences than those defining separate song types. The principal evidence that switching between song types functions as an aggressive signal, in song sparrows and other species, is that song type switching frequencies increase during aggressive contexts, for example during simulated territorial intrusions. We tested whether variant switching frequencies change in the same way, using playback of conspecific song to simulate intrusions. Male song sparrows showed a significant increase in variant switching frequencies during intrusion relative to before intrusion. After intrusions, variant switching frequencies returned to pre-intrusion levels. These results are consistent with the hypothesis that variant switching is a graded aggressive signal, but other interpretations are possible, for example, that variant switching is a signal of submission or represents simple production error. Received: 20 January 2000 / Revised: 15 July 2000 / Accepted: 30 July 2000