Dairy systems are a source of pollutant emissions, such as greenhouse gases (GHG) and NH3 that are associated with impacts on the environment. Gas emissions in barns are related mainly to diet intake and chemical composition, N excretion and manure management. A reduction in dietary N is known to be an effective way to reduce N excretion and the resulting NH3 emissions. However, most studies consider manure in liquid form with frequent removal from the barn. In deep litter systems, several processes can occur during the accumulation of solid manure that result in variable gas emissions. The objective of this experiment was to investigate the influence of the interaction between dietary CP (low or high) and manure management (liquid or solid) on gas emissions (NH3, N2O, CH4) at the barn level. Dietary treatments provided either low (LowN; 12% CP) or high (HighN; 18% CP) degradable protein to modify the amount of total ammonia nitrogen (TAN) excreted. The cows were housed for two 8-week periods in two mechanically ventilated rooms equipped to manage manure either in liquid (LM; slurry) or solid form (SM; deep litter). In the LM treatment, N balance was measured for 4 days. As expected, animals fed the LowN diet ingested 35% less N and excreted 65% less N in their urine, with no reduction in faecal N excretion and N secretion in milk. On the LowN diet, excretion of urea-N and NH3-N emissions were reduced regardless of the manure management. On the HighN diet, urinary urea-N excretion was three times as high, while NH3-N emissions were 3.0 and 4.5 times as high in LM and SM, respectively. Manure management strongly influenced CH4-C emissions, which were 30% higher in SM than in LM, due to the accumulation of litter. Moreover, gas emissions from solid manure increased over the accumulation period, except for NH3 on the LowN diet. Finally, our results suggest that methods used for national inventories would become more accurate by considering the variability in TAN excretion, which is the primary factor that influences NH3 emissions.

This study aimed at evaluating short- and long-term effects of housing beef cattle on deep litter (DL) or concrete fully slatted floor (FS) on their welfare. Animal-based measures of the Welfare Quality® assessment protocol for cattle were used to assess health status and behaviour of bulls. The assessment was carried out in a large commercial farm on 15 batches of bulls (4 DL and 11 FS) 1 month after their receiving day (short-term) and on 12 batches (three DL and nine FS) the week before slaughter (long-term). Signs of better comfort on deep litter in terms of shorter lying down durations (5.1±0.5 v. 6.5±0.4 s; P<0.05) and lower risk of hairless patches (odds ratio=0.09; 95% confidence interval=0.01 to 0.68; P<0.05) were already observed after 1 month. Heavy bulls after a long-term housing on FS showed a higher prevalence of bursitis, hairless patches and lesions/swellings than animals on DL. Bulls on fully slatted floor were at higher risk of early culling (odds ratio=6.44; 95% confidence interval=1.57 to 26.37; P<0.01), mainly due to musculoskeletal system pathologies/lameness. Deep litter proved to be a valid alternative to slatted floor, making animals more confident to interact with powerful movements such as mounting at the end of the finishing period. A negative aspect of the deep litter was the poor cleanliness of the bulls. Compared with the fully slatted floor, there were higher odds ratios for dirty bulls at both, the short- (odds ratio=25.09; 95% confidence interval=8.96 to 70.22; P<0.001) and the long-term housing (odds ratio=276.13; 95% confidence interval=98.21 to 776.38; P<0.001). In order to improve health and welfare of beef cattle finished at a heavy weight, deep litter systems are a promising alternative to fully slatted floors. However, proper management of deep litter is necessary to maintain satisfactory cleanliness of the bulls.

Indoor transmission of Ascaris suum partly depends on the physico-chemical conditions in bedding material. Temperature, pH, aqueous ammonia, moisture, occurrence and development of A. suum eggs were therefore compared in different areas (resting, intermediate and latrine) of two deep litter pens on an organic farm in four seasons. There was some variation, but mean ammonia levels were generally very low (1·0–2·6 mm) and pH levels were moderate (8·04–8·88) in all three areas. Relatively, resting areas were characterized by overall moderate moisture (36%) and moderately high temperature (35·7 °C) levels. The area contained few eggs (50 eggs g−1 DM) of which 17% were viable, and though only 4% were larvated and 0·7% appeared infective, it was more than in the other areas. Intermediate areas had moderate moisture (43%) and high temperature (43·6 °C) levels. There were many eggs (523 eggs g−1 DM), but overall viability was very low (5%) and few eggs were larvated (0·004%) or even infective (0·002%). Latrines typically had high moisture (79%) and moderate temperature (30 °C) levels. The concentration of eggs was very high (1444 egg g−1 DM) and though 32% were viable, none had developed larval stages. The large majority of A. suum eggs appear to die and only few become infective while in the deep litter. However, a large fraction of eggs may remain viable for some time and could thus contaminate agricultural land and develop to infectivity, if the manure is not composted appropriately.

In the European Union, the group-housed pregnant sows have to have a minimal legal available area of 2.25 m2/sow. However, it has been observed that an increased space allowance reduces agonistic behaviour and consecutive wounds and thus induces better welfare conditions. But, what about the environmental impacts of this greater available area? Therefore, the aim of this study was to quantify pollutant gases emissions (nitrous oxide, N2O, methane, CH4, carbon dioxide, CO2 and ammonia, NH3), according to the space allowance in the raising of gestating sows group-housed on a straw-based deep litter. Four successive batches of 10 gestating sows were each divided into two homogeneous groups and randomly allocated to a treatment: 2.5 v. 3.0 m2/sow. The groups were separately kept in two identical rooms. A restricted conventional cereals based diet was provided once a day in individual feeding stalls available only during the feeding time. Rooms were automatically ventilated. The gas emissions were measured by infra red photoacoustic detection during six consecutive days at the 6th, 9th and 12th weeks of gestation. Sows performance (body weight gain, backfat thickness, number and weight of piglets) was not significantly different according to the space allowance. In the room with 3.0 m2/sow and compared with the room with 2.5 m2/sow, gaseous emissions were significantly greater for NH3 (6.29 v. 5.37 g NH3-N/day per sow; P < 0.01) and significantly lower for N2O (1.78 v. 2.48 g N2O-N/day per sow; P < 0.01), CH4 (10.15 v. 15.21 g/day per sow; P < 0.001), CO2 equivalents (1.11 v. 1.55 kg/day per sow; P < 0.001), CO2 (2.12 v. 2.41 kg/day per sow; P < 0.001) and H2O (3.10 v. 3.68 kg/day per sow; P < 0.001). In conclusion, an increase of the available area for group-housed gestating sow kept on straw-based deep litter seems to be ambiguous on an environmental impacts point of view. Compared with a conventional and legal available area, it favoured NH3 emissions, probably due to an increased emitting surface. However, about greenhouse gases, it decreased N2O, CH4 and CO2 emissions, probably due to reduced anaerobic conditions required for their synthesis, and led to a reduction of CO2 equivalents emissions.