Effect of dairy production system, breed and co-product handling methods on environmental impacts at farm level.

Six dairy farms with the same on-farm area and milk production were compared. One farm (G-No) used grass as the sole forage for a herd of Normande cows, a dual-purpose breed. Three farms, with Holstein cows, varied forage for the herd from grass only (G-Ho) to low (G/LM-Ho) or high (G/HM-Ho) proportion of maize silage in the total forage area. Finally, two farms based on G/LM-Ho and G/HM-Ho systems aimed to increase omega-3 fatty acids in the winter diets of cows (G/LM/O3-Ho, G/HM/O3-Ho). Allocation methods (biophysical, protein, economic allocation) and system expansion applied for co-product (milk and meat) handling were examined. The impact categories considered were climate change, climate change including the effects of land use and land use change (CC/LULUC), cumulative energy demand, eutrophication, acidification and land occupation. The impacts per kg of fat-and-protein-corrected milk (FPCM) of G-No were highest, followed by those of G-Ho, G/LM-Ho and G/HM-Ho, regardless co-product handling methods and impact categories (except for eutrophication). CC/LULUC per kg FPCM of G/LM/O3-Ho and G/HM/O3-Ho were both 1% and 3% lower than those of G/LM-Ho and G/HM-Ho, respectively, but other impacts were higher. With system expansion, impacts per kg FPCM were lower than when allocation methods were used. Enteric fermentation was the greatest contributor (45-50%) to CC/LULUC, while grass production was the most important contributor to other impacts. The highest CC/LULUC (for G-No) can be explained by (1) G-No having the lowest milk yield/cow (though it produced the most meat) and (2) the fact that grass required more N fertiliser, but had lower yields than silage maize, even though grassland sequestered C. Among Holstein systems, increasing cow productivity by increasing feed intake (including maize silage and supplementing with concentrate) decreased impacts of milk. Reducing replacement rate and age of first calving also decreased impacts of milk. Increasing cow productivity reduced the amount of on-farm area required to produce a given amount of milk. Thus, the "liberated" on-farm area of Holstein systems was used to produce cash crops, and total impacts of these systems were lower than those of G-No (except for eutrophication and land occupation).

Effect of farming practices for greenhouse gas mitigation and subsequent alternative land use on environmental impacts of beef cattle production systems.

This study evaluated effects of farming practice scenarios aiming to reduce greenhouse gas (GHG) emissions and subsequent alternative land use on environmental impacts of a beef cattle production system using the life cycle assessment approach. The baseline scenario includes a standard cow-calf herd with finishing heifers based on grazing, and a standard bull-fattening herd using a diet mainly based on maize silage, corresponding to current farm characteristics and management by beef farmers in France. Alternative scenarios were developed with changes in farming practices. Some scenarios modified grassland management (S1: decreasing mineral N fertiliser on permanent grassland; S2: decreasing grass losses during grazing) or herd management (S3: underfeeding of heifers in winter; S4: fattening female calves instead of being reared at a moderate growth rate; S5: increasing longevity of cows from 7 to 9 years; S6: advancing first calving age from 3 to 2 years). Other scenarios replaced protein sources (S7: partially replacing a protein supplement by lucerne hay for the cow-calf herd; S8: replacing soya bean meal with rapeseed meal for the fattening herd) or increased n-3 fatty acid content using extruded linseed (S9). The combination of compatible scenarios S1, S2, S5, S6 and S8 was also studied (S10). The impacts, such as climate change (CC, not including CO2 emissions/sequestration of land use and land-use change, LULUC), CC/LULUC (including CO2 emissions of LULUC), cumulative energy demand, eutrophication (EP), acidification and land occupation (LO) were expressed per kg of carcass mass and per ha of land occupied. Compared with the baseline, the most promising practice to reduce impacts per kg carcass mass was S10 (all reduced by 13% to 28%), followed by S6 (by 8% to 10%). For other scenarios, impact reduction did not exceed 5%, except for EP (up to 11%) and LO (up to 10%). Effects of changes in farming practices (the scenarios) on environmental impacts varied according to impact category and functional unit. For some scenarios (S2, S4, S6 and S10), permanent grassland area and LO per kg of carcass decreased by 12% to 23% and 9% to 19%, respectively. If the 'excess' permanent grassland was converted to fast-growing conifer forest to sequester carbon in tree and soil biomass, CC/LULUC per kg of carcass could be reduced by 20%, 25%, 27% and 48% for scenarios S2, S4, S6 and S10, respectively. These results illustrate the potential of farming practices and forest as an alternative land use to contribute to short- and mid-term GHG mitigation of beef cattle production systems.

Enteric methane production and greenhouse gases balance of diets differing in concentrate in the fattening phase of a beef production system.

The purposes of this study were 1) to assess the effects of 3 high-concentrate diets on enteric CH(4) production, total tract digestibility, and rumen fermentation of beef cattle, and 2) to evaluate, by life cycle assessment, the potential effects of these feeding systems on the environment. Six bulls (age of 12.4 mo and BW of 417 kg at midexperiment) of the Blond d'Aquitaine breed were assigned to 3 dietary treatments in a replicated 3 × 3 Latin square design. Diets consisted of 1) 49% natural grassland hay, 41% ground corn grain, and 10% soybean meal (hay); 2) 63% corn silage, 21% ground corn grain, and 16% soybean meal (CS); and 3) 70% ground corn grain, 16% soybean meal, and 14% wheat straw (CG). Daily CH(4) emission (g/d), measured using the sulfur hexafluoride tracer technique, was similar for the hay and CS diets and was 56% greater than for the CG diet (P < 0.001). This difference between diets was maintained when CH(4) output was expressed by unit of feed intake (P < 0.001) or digested feed (P < 0.001). Gross energy intake loss as CH(4) averaged 6.9% for the hay and CS diets and 3.2% for the CG diet (P < 0.001). Organic matter intake and GE intake did not differ between diets. Organic matter digestibility was less for the hay diet than for the CS and CG diets (P=0.008). Digestibility of NDF was greatest for the hay diet, intermediate for the CS diet, and least for the CG diet (P=0.02), with ADF digestibility being similar between the hay and CS diets and greater than for the CG diet (P < 0.001). The rumen pH at 5 h postfeeding was less for animals fed the CG diet compared with those fed the other 2 diets (on average, 5.1 vs. 5.9, respectively; P < 0.001). Total CH(4) emission (enteric + manure) was least for the CG diet, whereas N(2)O and CO(2) emissions were greatest for the CG diet. Total greenhouse gas emissions were least for the CG diet when C sequestration by grasslands was not taken into account.

Evaluation of the environmental implications of the incorporation of feed-use amino acids in the manufacturing of pig and broiler feeds using Life Cycle Assessment.

The incorporation of feed-use (FU) amino acids (AAs) in diets results in a reduced use of protein-rich ingredients such as soybean meal, recognized to have elevated contributions to environmental impacts. This study investigated whether the incorporation of L-lysine.HCl, L-threonine and FU-methionine reduces the environmental impacts of pig and broiler feeds using Life Cycle Assessment. The following impact categories were considered: climate change, eutrophication, acidification, terrestrial ecotoxicity, cumulative energy demand and land occupation. Several feeds were formulated either to minimize the cost of the formulation (with or without AA utilization), to maximize AA incorporation (i.e. the cost of AA was considered to be similar to that of soybean meal), or to minimize greenhouse gas emissions. For both pig and broiler feeds, calculations were made first using only cereals and soybean meal as main ingredients and then using cereals and several protein-rich ingredients (soybean meal, rapeseed meal and peas). In addition, these calculations were performed using two types of soybean meal (from Brazil, associated with recent deforestation or not). For broiler feeds, two types of maize (from France, irrigated, with mineral fertilization v. not irrigated, with animal manure fertilization) were also tested. Regarding the feeds formulated to minimize cost, incorporation of AA decreased the values for eutrophication, terrestrial ecotoxicity and cumulative energy demand of both pig and broiler feeds, regardless of the base ingredients. Reduction in climate change and acidification due to the incorporation of AA depended on the nature of the feed ingredients, with the effect of AA incorporation being greater when combined with ingredients with high impacts such as soybean meal associated with deforestation. Feeds formulated to maximize AA incorporation generally had a similar composition to those formulated to minimize cost, suggesting that the costs of AA were not the limiting factor in their incorporation. Feeds formulated to minimize greenhouse gas emissions had the lowest values for climate change and cumulative energy demand, but not for other impacts. Further research is needed to elucidate whether the incorporation of additional AA (tryptophan and valine) along with L-lysine, L-threonine and FU-methionine could decrease on the environmental impacts of pig and broiler feeds further.

Nitrogen fertilization and sex expression affect size variability of fibre hemp (Cannabis sativa L.).

Mechanical harvesting and industrial processing of fibre hemp (Cannabis sativa L.) require uniformity of stem length and weight. In 1991 and 1992 we carried out field experiments to investigate the effects of soil nitrogen level (80 and 200 kg ha-1N) and row width (12.5, 25 and 50 cm) on the variability of weight and height in hemp plants. The crops were sampled 5 times between early June and early September. Row width did not affect size variability. At final harvest coefficients of variation (CV) of both weight and height were about 1.5 times higher at 200 than at 80 kg ha-1N. Distributions of dry weight were positively skewed at all sampling dates except the first, with skewness larger at 200 than at 80 kg ha-1N. Distributions of height were negatively skewed at all sampling dates except the first at 80 kg ha-1N. At 200 kg ha-1N they changed from negative skewness during the first part of the growing season to negative kurtosis in the second part of the growing season. More suppressed plants were present at 200 than at 80 kg ha-1N. Contrary to most published results, we did not find a reduction of CV of weight nor of CV of height at the onset of self-thinning. Suppressed hemp plants can survive relatively well in the low-light environment under the canopy. Sexual dimorphism contributed to variability of height and weight, but the effects were smaller than those of nitrogen fertilization. The ratio of female to male plants was higher at 200 than at 80 kg ha-1N, as a result of a shift in sex-ratio within the population of suppressed plants. As suppressed plants were much more slender than dominating plants, self-thinning eliminated the most slender individuals in a hemp crop. However, the presence of many more heavy individuals of low slenderness at 200 than at 80 kg ha-1 N was probably the major cause of the difference in slenderness between 200 and 80 kg ha-1 N.