A stochastic bio-economic pig farm model to assess the impact of innovations on farm performance

Recently developed innovations may improve the economic and environmental sustainability of pig production systems. Generic models are needed to assess the impact of innovations on farm performance. Here we developed a stochastic bio-economic farm model for a typical farrow-to-finish pig farm to assess the impact of innovations on private and social profits. The model accounts for emissions of greenhouse gases from feed production and manure by using the shadow price of CO₂, and for stochasticity of economic and biological parameters. The model was applied to assess the impact of using locally produced alternative feed sources (i.e. co-products) in the diets of finishing pigs on private and social profits of a typical Brazilian farrow-to-finish pig farm. Three cases were defined: a reference case (with a standard corn–soybean meal-based finishing diet), a macaúba case (with a macaúba kernel cake-based finishing diet) and a co-products case (with a co-products-based finishing diet). Pigs were assumed to be fed to equal net energy intakes in the three cases. Social profits are 34% to 38% lower than private profits in the three cases. Private and social profits are about 11% and 14% higher for the macaúba case than the reference case, whereas they are 3% and 7% lower for the co-products case, respectively. Environmental costs are higher under the alternative cases than the reference case suggesting that other benefits (e.g. costs and land use) should be considered to utilize co-products. The CV of farm profits is between 75% and 87% in the three cases following from the volatility of prices over time and variations in biological parameters between fattening pigs.     

Social facilitation in the feeding behaviour of pigs and the effect of rank

Two groups each of three fattening pigs were used. After the rank order had been determined, the animals in each group were deprived of food for 12 hours. One was then left in the experimental room, given food ad libitum, and allowed to eat to satiation. Within 10 minutes of having stopped feeding, one of the others from its group was put in the adjacent stall and allowed to feed. In all cases, the apparently satiated pig started to feed when the newly-introduced pig started to feed. When used as the remaining pig, the dominant pig in each group fed for longer and ate more than the other-ranking pigs when a hungry pig was introduced into the next-door stall. In order to test whether the resumption of feeding was due to the cessation of isolation or due to the feeding behaviour of the introduced pig, a second experiment was performed. The same groups were used plus another group of three similar pigs. After 12 hours of food deprivation, two pigs were left in adjacent stalls and allowed to feed until satiated. The third member of their group was then introduced and allowed to feed in a stall facing the other two. In all cases the remaining pair fed for appreciable periods. These results confirm that social facilitation, as defined here, occurred in the feeding behaviour of these pigs.     

Mixed crop–livestock farming systems: a sustainable way to produce beef? Commercial farms results,questions and perspectives

Mixed crop–livestock (MC–L) farming has gained broad consensus as an economically and environmentally sustainable farming system. Working on a Charolais-area suckler cattle farms network, we subdivided the 66 farms of a constant sample, for 2 years (2010 and 2011), into four groups: (i) ‘specialized conventional livestock farms’ (100% grassland-based farms (GF), n=7); (ii) ‘integrated conventional crop–livestock farms’ (specialized farms that only market animal products but that grow cereal crops on-farm for animal feed, n=31); (iii) ‘mixed conventional crop–livestock farms’ (farms that sell beef and cereal crops to market, n=21); and (iv) organic farms (n=7). We analyse the differences in structure and in drivers of technical, economic and environmental performances. The figures for all the farms over 2 years (2010 and 2011) were pooled into a single sample for each group. The farms that sell crops alongside beef miss out on potential economies of scale. These farms are bigger than specialized beef farms (with or without on-farm feed crops) and all types of farms show comparable economic performances. The big MC–L farms make heavier and consequently less efficient use of inputs. This use of less efficient inputs also weakens their environmental performances. This subpopulation of suckler cattle farms appears unable to translate a MC–L strategy into economies of scope. Organic farms most efficiently exploit the diversity of herd feed resources, thus positioning organic agriculture as a prototype MC–L system meeting the core principles of agroecology.     

Environmental assessment of digestibility improvement factors applied in animal production

Background, Aims and Scope  

Many feed ingredients are not fully digested by livestock. However, the addition of digestibility-improving enzymes to the feed can improve the absorption of e.g. energy and protein and thereby enhance the nutrient value of the feed. Feed production is a major source of environmental impacts in animal production, and it is obvious to assume that enzyme supplementation can help to reduce the environmental impact of animal production. The purpose of the study is, therefore, to assess and compare the environmental burdens of the supplements and compare them with the savings made when enzymes are used in animal production. The properties of enzymes vary considerably and the study takes as its starting point a particular enzyme product, Ronozyme WX CT. Ronozyme WX CT is a xylanase which depolymerises xylans (a group of dietary fibres found in cereal cell walls) into smaller units. The product is a widely accepted means of improving the energy value and the protein digestibility of pig and poultry feed. The study relates to Ronozyme WX CT used for fattening pigs produced in Denmark.     

PASTRAB: a model for simulating intake regulation and growth of rabbits raised on pastures

Given the very recent investment in research on organic rabbit production, many knowledge gaps remain. Simulation models based on data from experiments and farms may help generate general principles for organic rabbit production. Our goals were to (i) develop a model to simulate intake regulation and growth of rabbits raised on pastures, (ii) validate this model under a diversity of conditions and (iii) conduct a simulation experiment to predict the potential to decrease the supply of complete feed by increasing the grazing area per rabbit. The model developed (PASTRAB) simulates organic rabbit fattening on pastures in four main submodels that represent dynamics of (i) herbage standing biomass, fill and feed values; (ii) intake of herbage, complementary feed (i.e. complete pellets, cereal–legume grain mixtures) and hay as regulated by herbage allowance, fill and feed values of feedstuffs and rabbit physiological parameters; (iii) conversion of rabbit intake into live weight gain; and (iv) rabbit mortality. The model also calculates gross margin per rabbit sold. Model accuracy was assessed by considering the fit between observed and predicted herbage intake, which was low, with a relative root mean square error (rRMSE) of 51% and 66% on grass-based and legume-based pastures, respectively. However, the standard deviations of observed herbage intake were similar to the root mean square error of predicted herbage intake, indicating that it would have been difficult to improve model calibration. The fit between observed and predicted rabbit live weight was acceptable, with an rRMSE of 11% and 10% for grass-based and legume-based pastures, respectively. Simulated scenarios showed that a decrease in complementary feed combined with an increase in the grazing area per rabbit had little impact on average daily growth and gross margin per rabbit but increased herbage use efficiency. With 90 g of complementary feed per day and grazing of 0.4 m²/rabbit per day, herbage use efficiency was 22%, with average daily growth of 21.6 g/day and gross margin of 18.80 €/rabbit. With no complementary feed and grazing of 1.2 m²/rabbit per day, average daily growth decreased (19.2 g/day), but herbage use efficiency reached 100% and gross margin reached 19.20 €/rabbit. We used PASTRAB in participatory workshops with farmers so that the latter could explore adaptations to their current practices. Overall, farmers considered the model predictions realistic, and some of them decided to adapt some of their management practices immediately after the workshops.     

Increasing daily feeding occasions in restricted feeding strategies does not improve performance or well being of fattening pigs

Background  

The natural feeding behaviour of the pig is searching for feed by rooting activities throughout the day; self-feeding pigs randomly space their eating and drinking periods throughout the day consuming ten to twelve meals per day. Pigs in conventional fattening pig production are normally fed 2–3 times daily with the feed consumed within 15 minutes. The aim of this study was to determine if more frequent feedings could improve the performance of conventionally kept fattening pigs.     

Effects of particle size and hydro-thermal treatment of feed on performance and stomach health in fattening pigs

Effects of grinding and hydro-thermal treatment of feed on growth performance, slaughter traits, nutrient digestibility, stomach content and stomach health were examined by using 96 crossbred fattening pigs. Pigs were fed a grain-soybean meal-based diet processed by various technical treatments. Feeding groups differed in particle size after grinding (finely vs. coarsely ground feed) and hydro-thermal treatment (without hydro-thermal treatment, pelleting, expanding, expanding and pelleting). Fine grinding and hydro-thermal treatment showed significant improvements on the digestibility of crude nutrients and content of metabolisable energy. Hydro-thermal treatment influenced average daily gain (ADG) and average daily feed intake (DFI) significantly. Finely ground pelleted feed without expanding enhanced performances by increasing ADG and decreasing feed-to-gain ratio (FGR) of fattening pigs. Coarsely ground feed without hydro-thermal treatment resulted in the highest ADG and DFI, however also in the highest FGR. Expanded feed decreased DFI and ADG. Slaughter traits were not affected by treatments. Coarsely ground feed without hydro-thermal treatment had protective effects on the health of gastric pars nonglandularis, however, pelleting increased gastric lesions. Hydro-thermal treatment, especially expanding, resulted in clumping of stomach content which possibly induced satiety by slower ingesta passage rate and thus decreased feed intake. Pigs fed pelleted feed showed less pronounced development of clumps in stomach content compared with expanded feed.     

Rearing performances and environmental assessment of sea cage farming in Tunisia using life cycle assessment (LCA) combined with PCA and HCPC

Purpose

The present study aims to understand the influence of rearing practices and the contributions of production phases of fish farming to their environmental impacts and determine which practices and technical characteristics can best improve the farms’ environmental performance. Another objective is to identify the influence of variability in farming practices on the environmental performances of sea cage aquaculture farms of sea bass and sea bream in Tunisia by using principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) methods and then combining the classification with life cycle assessment (LCA).

Methods

The approach consisted of three major steps: (i) of the 24 aquaculture farms in Tunisia, 18 were selected which follow intensive rearing practices in sea cages of European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) and then a typology was developed to classify the studied farms into rearing practice groups using HCPC; (ii) LCA was performed on each aquaculture farm and (iii) mean impacts and contributions of production phases were calculated for each group of farms. Impact categories included acidification, eutrophication, global warming, land occupation, total cumulative energy demand and net primary production use.

Results and discussion

Results revealed high correlation between rearing practices and impacts. The feed-conversion ratio (FCR), water column depth under the cages and cage size had the greatest influence on impact intensity. Rearing practices and fish feed were the greatest contributors to the impacts studied due to the production of fish meal and oil and the low efficiency of feed use, which generated large amounts of nitrogen and phosphorus emissions. It is necessary to optimise the diet formulation and to follow better feeding strategies to lower the FCR and improve farm performance. Water column depth greatly influenced the farms’ environmental performance due to the increase in waste dispersion at deeper depths, while shallow depths resulted in accumulation of organic matter and degradation of water quality. Cage size influences environmental performances of aquaculture farms. Thus, from an environmental viewpoint, decision makers should grant licences for farms in deeper water with larger cages and encourage them to improve their FCRs.

Conclusions

This study is the first attempt to combine the HCPC method and the LCA framework to study the environmental performance of aquacultural activity. The typology developed captures the variability among farms because it considers several farm characteristics in the classification. The LCA demonstrated that technical parameters in need of improvement are related to the technical expertise of farm managers and workers and to the location of the farm.

     

Economic weights of fertility, prolificacy, milk yield and longevity in dairy sheep

Economic weights have been estimated in two breeds (Latxa and Manchega) using economic and technical data collected in 41 Latxa and 12 Manchega dairy sheep flocks. The traits considered were fertility (lambing per year), prolificacy (number of lambs), milk yield (litres) and longevity (as productive life, in years). A linear function was used, relating these traits to the different costs in the flock. The variable costs involved in the profit function were feed and labour. From this function, economic weights were obtained. Labour is considered in the Latxa breed to be a constraint. Moreover, farm profits are unusually high, which probably means that some costs were not included according to the economic theory. For that reason, a rescaling procedure was applied constraining total labour time at the farm. Genetic gains were estimated with the resulting economic weights to test if they give any practical difference. Milk yield only as selection criterion was also considered. The medians of the estimated economic weights for fertility, prolificacy, milk yield and longevity were 138.60 € per lambing, 40.00 € per lamb, 1.18 € per l, 1.66 € per year, and 137.66 € per lambing, 34.17 € per lamb, 0.73 € per l, 2.16 € per year under the linear approach in the Latxa and Manchega breeds respectively. Most differences between breeds can be related to differences in production systems. As for the genetic gains, they were very similar for all economic weights, except when only milk yield was considered, where a correlated decrease in fertility led to a strong decrease in profit. It is concluded that the estimates are robust for practical purposes and that breeding programmes should consider inclusion of fertility. More research is needed to include other traits such as somatic cell score, milk composition and udder traits.     

Involvement of small-scale dairy farms in an industrial supply chain: when production standards meet farm diversity

In certain contexts, dairy firms are supplied by small-scale family farms. Firms provide a set of technical and economic recommendations meant to help farmers meet their requirements in terms of the quantity and quality of milk collected. This study analyzes how such recommendations may be adopted by studying six farms in Brazil. All farms are beneficiaries of the country's agrarian reforms, but they differ in terms of how they developed their activities, their resources and their milk collection objectives. First, we built a technical and economic benchmark farm based on recommendations from a dairy firm and farmer advisory institutions. Our analysis of the farms' practices and technical and economic results show that none of the farms in the sample apply all of the benchmark recommendations; however, all farms specialized in dairy production observe the main underlying principles with regard to feeding systems and breeding. The decisive factors in whether the benchmark is adopted and successfully implemented are (i) access to the supply chain when a farmer establishes his activity, (ii) a grasp of reproduction and forage production techniques and (iii) an understanding of dairy cattle feed dietary rationing principles. The technical problems observed in some cases impact the farms' dairy performance and cash position; this can lead to a process of disinvestment. This dynamic of farms facing production standards suggests that the diversity of specialized livestock farmers should be taken into account more effectively through advisory approaches that combine basic zootechnical training with assistance in planning farm activities over the short and medium term.     

Environmental impact of replacing soybean meal with rapeseed meal in diets of finishing pigs

The major impact of the livestock sector on the environment may be reduced by feeding agricultural co-products to animals. Since the last decade, co-products from biodiesel production, such as rapeseed meal (RSM), became increasingly available in Europe. Consequently, an increase in RSM content in livestock diets was observed at the expense of soybean meal (SBM) content. Cultivation of SBM is associated with high environmental impacts, especially when emissions related to land use change (LUC) are included. This study aims to assess the environmental impact of replacing SBM with RSM in finishing pig diets. As RSM has a lower nutritional value, we assessed the environmental impact of replacing SBM with RSM using scenarios that differed in handling changes in nutritional level. Scenario 1 (S1) was the basic scenario containing SBM. In scenario 2 (S2), RSM replaced SBM based on CP content, resulting in reduced energy and amino acid content, and hence an increased feed intake to realize the same growth rate. The diet of scenario 3 (S3) was identical to S2; however, we assumed that pigs were not able to increase their feed intake, leading to reduced growth performance. In scenario 4 (S4), the energy and amino acid content were increased to the same level of S1. Pig performances were simulated using a growth model. We analyzed the environmental impact of each scenario using life-cycle assessment, including processes of feed production, manure management, piglet production, enteric fermentation and housing. Results show that, expressed as per kg of BW, replacing SBM with RSM in finishing pig diets marginally decreased global warming potential (GWP) and energy use (EU) but decreased land use (LU) up to 12%. Between scenarios, S3 had the maximum potential to reduce the environmental impact, due to a lower impact per kg of feed and an increased body protein-to-lipid ratio of the pigs, resulting in a better feed conversion ratio. Optimization of the body protein-to-lipid ratio, therefore, might result in a reduced environmental impact of pig production. Furthermore, the impact of replacing SBM with RSM changed only marginally when emissions related to direct (up to 2.9%) and indirect LUC (up to 2.5%) were included. When we evaluated environmental impacts of feed production only, which implies excluding other processes along the chain as is generally found in the literature, GWP decreased up to 10%, including LUC, EU up to 5% and LU up to 16%.     

Economic evaluation of the environmental impact of a dairy cattle intensive production cluster under arid lands conditions

At a global level, dairy cow production systems (DCPS) are important sources of nourishment and profits, but they generate environmental impacts such as overexploitation of different resources including water, lands and fossil energy. Quantification of water and carbon footprint to define mitigation strategies and a more rational use of natural resources, is a reiterated claim. The aim of this study was to perform an economic evaluation of the environmental impact of the DCPS from the Comarca Lagunera, Mexico (24°N, 102°W, 220 mm, hot-semiarid climate) We contrasted the economic value (EV) generated by the DCPS with respect to the economic costs (EC) due to the greenhouse gas emissions (GHGE) and the water footprint (WFP) of this DCPS. While quantifications of GHGE considered those proposed by the Intergovernmental Panel on Climate Change, the WFP involved the use of blue, gray and green water by the DCPS and related activities. Quantification of the EC of WFP considered an international average price of water. In the year 2017, the Comarca Lagunera registered a dairy cow inventory of 493 144 heads, with 227 142 lactating cows, which produced 2386 million liters of milk per year with an annual average EV of €525.3 million. The EC (€, millions) generated by the GHGE and WFP were €311.8 and €11 980.7, respectively, with a total EC of € 12 292.5 million. When the EV of milk production and the total environmental EC are compared, the contrast demonstrates not only the noteworthy environmental impact but also the significant and senseless biological and EC. In addition, having a large dairy cow concentration creates pollution concerns and the DCPS transfers both nutrients and water resources from an ecologically vulnerable arid region. Therefore, some mitigation strategies such as, better cow genotype, feed and manure management combined with the production of forages and grains in a different geographical region are suggested to promote an optimum use of water in order to uphold the social, economic and biologic sustainability of the Comarca Lagunera, Mexico.     

Economic and environmental performance of miscanthus cultivated on marginal land for biogas production

Environmental issues surrounding conventional annual biogas crops have led to growing interest in alternative crops, such as miscanthus. In addition to the better environmental performance, miscanthus can be grown on marginal land where no competition with feed and food crops is anticipated. On marginal land however, biomass yields are significantly lower than on good agricultural land. This raises the question of the economic and environmental sustainability of miscanthus cultivated on marginal land for biogas production. This study assessed the environmental and economic performance of miscanthus cultivated on marginal land for biogas production by conducting a Life‐Cycle Assessment and complementary Life‐Cycle Cost analysis. The functional unit chosen was 1 GJ of electricity (GJ_el.). The substitution of a fossil reference was included using a system expansion approach. Electricity generated by the combustion of miscanthus‐based biogas in a combined heat and power has considerably lower impacts on the environment than the fossil reference in most of the categories assessed. In the impact category “climate change”, the substitution of the marginal German electricity mix leads to a carbon mitigation potential of 256 kg CO₂e/GJ_el.. At 45.12 €/GJ_el., the costs of miscanthus‐based biogas generation and utilization are considerably lower than those of maize (61.30 €/GJ_el.). The results of this study clearly show that it can make economic and environmental sense to cultivate miscanthus on marginal land as a substrate for biogas production. The economic sustainability is however limited by the biomass yield. By contrast, there are no clear thresholds limiting the environmental performance. The decision needs to be made on a case‐by‐case basis depending on site‐specific conditions such as local biodiversity.     

Technical and economic potentials of the unconventional extruded dried Arabic bread wastes in broilers diets

Food waste is one of the major global challenges that have adverse socioeconomic and environmental impacts. Therefore, studying food waste utilization potentials and minimizing its negative consequences becomes imperative. This study aims to assess the technical and economic potentials of substituting corn with unconventional extruded dried Arabic Bread waste (EDABW) in broilers’ diets, in terms of broilers’ performance, carcass characteristic, economic net returns, and income over feed cost (IOFC). One hundred eighty unsexed one-day-old broiler birds of Ross breed were distributed randomly in six treatments (0, 20, 40, 60, 80, and 100% EDABW group) of isocaloric and isonitrogenous diets in a completely randomized design with six replicated (5 chicks/replicate). The investigated traits were broilers’ performance (live body weight, total feed intake, total feed conversion ratio, and total weight gain. Other traits such as carcass weight, abdominal fat, edible offal (liver, heart, and gizzard), eviscerated (breast muscles, drum and thigh muscles, and wings) were weighed and expressed based on a live body weight. Results showed that the 20% replacement level of corn with EDABW generated the highest increase in the live body weight and the eviscerated carcass at about 4.24% g and 4.90%, respectively. On the other hand, the economic analysis showed potential reductions in the broilers’ diet cost and the total broilers' production cost as the levels of corn substitution with by unconventional EDABW increased. The reductions were estimated at 5.1%, 6.3%, 8.4%, 9.3%, and 9.9% at substitution levels of 20%, 40%, 60%, 80%, and 100%, respectively as compared to the control diet. The results also showed a potential increase in the net economic returns of broiler meat as the increase in substitution levels ranged between 3.5–06.8% and 4.3–8.3% as compared to the control diets using the average retail and wholesale prices of broiler meats, respectively. In addition, the maximum IOFC was estimated potentially at a 20% substitution level of corn with EDABW. Conclusively, the study results show promising technical and economic potentials for unconventional EDABW in broilers’ diets that could lead to a thriving industry of unconventional broilers’ diets with high net economic returns and maximum IOFC.     

Implications of Uncertainty and Variability in the Life Cycle Assessment of Pig Production Systems(7 pp)

Goal, Scope and Background Calculating LCA outcomes implies the use of parameters, models, choices and scenarios which introduce uncertainty, as they imperfectly account for the variability of both human and environmental systems. The analysis of the uncertainty of LCA results, and its reduction by an improved estimation of key parameters and through the improvement of the models used to convert emissions into regional impacts, such as eutrophication, are major issues for LCA. Methods In a case study of pig production systems, we propose a simple quantification of the uncertainty of LCA results (intra-system variability) and we explore the inter-system variability to produce more robust LCA outcomes. The quantification of the intra-system uncertainty takes into account the variability of the technical performance (crop yield, feed efficiency) and of emission factors (for NH3, N2O and NO3) and the influence of the functional unit (FU) (kg of pig versus hectare used). For farming systems, the inter-system variability is investigated through differentiating the production mode (conventional, quality label, organic (OA)), and the farmer practices (Good Agricultural Practice (GAP) versus Over Fertilised (OF)), while for natural systems, variability due to physical and climatic characteristics of catchments expected to modify nitrate fate is explored. Results and Conclusion For the eutrophication and climate change impact categories, the uncertainty associated with field emissions contributes more to the overall uncertainty than the uncertainty associated with emissions from livestock buildings, with crop yield and with feed efficiency. For acidification, the uncertainty of emissions from livestock buildings is the single most important contributor to the overall uncertainty. The influence of the FU on eutrophication results is very important when comparing systems with different degrees of intensification such as GAP and OA. Concerning the inter-system variability, differences in farmer practices have a larger effect on eutrophication than differences between production modes. Finally, the physical characteristics of the catchment and the climate strongly affect the results for eutrophication. In conclusion, in this case study, the main sources of uncertainty are in the estimation of emission factors, due both to the variability of environmental conditions and to lack of knowledge (emissions of N2O at the field level), but also in the model used for assessing regional impacts such as eutrophication. Recommendation and Perspective Suitable deterministic simulation models integrating the main controlling variables (environmental conditions, farmer practices, technology used) should be used to predict the emissions of a given system as well as their probabilistic distribution allowing the use of stochastic modelling. Finally, our simulations on eutrophication illustrate the necessity of integrating the fate of pollutants in models of impact assessment and highlight the important margin of improvement existing for the eutrophication impact assessment model.     

A comparison of models for predicting slurry production on a pig farm

Three methods of predicting slurry production were compared with the volumes actually produced on a 150 sow breeding and fattening pig unit. The methods were based on (a) feed, water and slurry relationships measured in crated and penned pigs; (b) values given in the literature and used by ADAS to predict slurry outputs from pigs; (c) a method based on the digestibility of feed and of water measured at the actual piggery. Method (a) was not found appropriate because of the high overall water:meal ratio found in the unit (13:1). Method (b) was able to predict dry matter production accurately but underestimated the volume produced unless the ADAS allowance of 0·5 litres pig⁻¹ day⁻¹ for washing water and leaking drinkers was increased to 10 litres. Method (c) was the best method for estimating volume but underestimated dry matter production. Combining the better aspects of methods (b) and (c) allows volume, dry matter production and dry matter concentration to be predicted satisfactorily. The daily movements of slurry from the reception pit were very variable. The use of water meters on pig units is recommended to identify wastage.     

Breeding replacement gilts for organic pig herds

In this study, breeding structures and commercial sow lines were evaluated by economic and genetic simulation studies for their suitability to provide the Dutch organic pig sector with replacement gilts. Sow and litter performance from over 2000 crossbred sows from 2006 to 2007 were collected on 11 to 14 Dutch organic pig herds, respectively, and compared with conventional herds. Results showed that organic herds had lower farrowing rates (3.6% to 7.5%), more live born piglets per litter (0.4% to 1.2%) and higher preweaning mortality rates (7% to 13%) compared to conventional herds. These results were used to simulate economic performance of various combinations of breeding structures and sow lines under organic conditions, under the assumption of absence of genotype-environment interactions. Sow and litter performance data under organic conditions (total piglets born/litter, stillborn piglets/litter, mortality until weaning, lactation length, interval weaning-oestrus and sow culling rate) and the costprice calculation for the Dutch organic pig sector were used as input for the economic simulation studies. The expected genetic progress was simulated for three potential breeding structures of the organic sector: organic breeding herds producing F1 gilts (OrgBS), a flower breeding system (FlowerBS) and a two-line rotation breeding system (RotBS). In FlowerBS, an organic purebred sow line is bred, using on-farm gilt replacement. The OrgBS with a Yorkshire × Landrace cross had the highest margin per sow place (€779), followed by RotBS with Yorkshire × Landrace cross (€706) and FlowerBS with Yorkshire sow line (€677). In case that an organic purebred sow population of 5000 sows would be available, FlowerBS gave the highest genetic progress in terms of cost price reduction (€3.72/slaughter pig per generation), followed by RotBS and OrgBS (€3.60/slaughter pig per generation). For FlowerBS, additional costs will be involved for maintaining a dedicated breeding programme. In conclusion, OrgBS using conventional genetics is economically the most viable option for the organic pig sector. However, this structure has clear disadvantages in terms of risks with regard to disease transmission and market demand. FlowerBS using a dedicated purebred organic line will only be cost-effective if sow population size is sufficiently large. RotBS might be a viable alternative, especially in combination with artificial insemination (AI) boars that are ranked according to an organic selection index. Regardless of breeding structure, the Yorkshire sow line gave the highest prolificacy and the highest economic returns on organic herds.     

Feed restriction strategy in the growing rabbit. 2. Impact on digestive health, growth and carcass characteristics

A field enquiry mentioned the potential positive impact of a feed restriction on the health of young rabbits, but no objective information relates the intake to digestive health. The effects of a post-weaning feed restriction strategy were thus studied on digestive health and growth and carcass parameters of the growing rabbit, using a monofactorial design that produces a quantitative linear reduction of the intake, from ad libitum (AL group) to 80%, 70% and 60% of AL. The study was performed simultaneously in six experimental sites, on 1984 growing rabbits (496 per treatment) collectively caged from weaning (34 to 38 days of age, depending on the site) to slaughter (68 to 72 days). The feeding programme was applied as followed: restriction during 21 days after weaning, and then ad libitum till slaughter. During the feed restriction period the growth rate was linearly reduced with the restriction level, by 0.5 g/day for each percent of intake reduction. When returning to ad libitum intake (after 54 days old) a compensatory growth and a higher feed efficiency occurred. Therefore, the impact of the feeding programme on the slaughter weight (SW) was significant (-4.5 g/% of restriction), but relatively moderate: the weight loss of the more-restricted rabbits (60%) reached 7.7% (-200 g) compared to the AL group. Over the whole fattening period, the feed restriction reduced linearly and significantly the feed conversion (FC) (-0.0077 unit/% of restriction). Carcass traits were little affected by the feeding programme, except for a slightly lower decrease of the dressing percentage (mean: 1.2 units between AL and the three restricted groups). On the six experimental sites, mortality and morbidity were always caused by acute digestive disorders, namely diarrhoea and/or caecal impaction. Independent of the treatment, the mortality rate strongly varied according to the site (between 7% and 18% from weaning to 54 days and for the AL group). During feed restriction, the mortality was significantly lower from a restriction threshold of 80% (meanly: -9% compared to AL). The morbidity was also significantly reduced (-6%) for the two most restricted groups (70% and 60%). The favourable effect of a lower intake on health did not persist after returning to ad libitum intake (54 days to slaughter), since mortality and morbidity were not significantly different among the treatments. Such a feeding strategy thus represents a double benefit in terms of feed costs and lower losses of young rabbits.     

Evaluating environmental impacts of selection for residual feed intake in pigs

To identify a proper strategy for future feed-efficient pig farming, it is required to evaluate the ongoing selection scenarios. Tools are lacking for the evaluation of pig selection scenarios in terms of environmental impacts to provide selection guidelines for a more sustainable pig production. Selection on residual feed intake (RFI) has been proposed to improve feed efficiency and potentially reduce the associated environmental impacts. The aim of this study was thus to develop a model to account for individual animal performance in life cycle assessment (LCA) methods to quantify the responses to selection. Experimental data were collected from the fifth generation of pig lines divergently selected for RFI (low line, more efficient pigs, LRFI; high line, less efficient pigs, HRFI). The average feed conversion ratio (FCR) and daily feed intake of LRFI pigs were 7% lower than the average of HRFI pigs (P < 0.0001). A parametric model was developed for LCA based on the dietary net energy fluxes in a pig system. A nutritional pig growth tool, InraPorc®, was included as a module in the model to embed flexibility for changes in feed composition, animal performance traits and housing conditions and to simulate individual pig performance. The comparative individual-based LCA showed that LRFI had an average of 7% lower environmental impacts per kilogram live pig at farm gate compared to HRFI (P < 0.0001) on climate change, acidification potential, freshwater eutrophication potential, land occupation and water depletion. High correlations between FCR and all environmental impact categories (>0.95) confirmed the importance of improvement in feed efficiency to reduce environmental impacts. Significant line differences in all impact categories and moderate correlations with impacts (>0.51) revealed that RFI is an effective measure to select for improved environmental impacts, despite lower correlations compared to FCR. Altogether more optimal criteria for efficient environment-friendly selection can then be expected through restructuring the selection indexes from an environmental point of view.