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Abstract. Nitrogen losses via nitrate leaching, ammonia volatilization and nitrous oxide emissions were measured from contrasting outdoor pig farming systems in a two year field study. Four 1-ha paddocks representing three outdoor pig management systems and an arable control were established on a sandy loam soil in Berkshire, UK. The pig management systems represented: (i) current commercial practice (CCP) -25 dry sows ha 71 on arable stubble; (ii)`improved' management practice (IMP) -18 dry sows ha 71 on stubble undersown with grass, and (iii)`best' management practice (BMP) 12 dry sows ha 71 on established grass. Nitrogen (N) inputs in the feed were measured and N offtakes in the pig meat estimated to calculate a nitrogen balance for each system.In the first winter, mean nitrate-N concentrations in drainage water from the CCP, IMP, BMP and arable paddocks were 28, 25, 8 and 10 mg NO 3 l 71 , respectively. On the BMP system, leaching losses were limited by the grass cover, but this was destroyed by the pigs before the start of the second drainage season. In the second winter, mean concentrations increased to 111, 106 and 105 mg NO 3 -N l 71 from the CCP, IMP and BMP systems, respectively, compared to only 32 mg NO 3 -N l 71 on the arable paddock. Ammonia (NH 3 ) volatilization measurements indicated that losses from outdoor dry sows were in the region of 11 g NH 3 -N sow 71 day 71. Urine patches were identified as the major source of nitrous oxide (N 2 O) emissions, with N 2 O-N losses estimated at less than 1% of the total N excreted. The nitrogen balance calculations indicated that N inputs to all the outdoor pig systems greatly exceeded N offtakes plus N losses, with estimated N surpluses on the CCP, IMP and BMP systems after 2 years of stocking at 576, 398 and 264 kg N ha 71, respectively, compared with 27 kg N ha 71 on the arable control.These large N surpluses are likely to exacerbate nitrate leaching losses in following seasons and make a contribution to the N requirement of future crops.

Mixing pigs from different social groups is known to cause turmoil which often results in skin lacerations as well as dark, firm and dry meat. Nine hundred and sixty commercial crossbred pigs were used for this experiment, divided into eight consignments. Within each consignment the pigs were divided into groups of about 15. The pigs in each group had coexisted for at least 6 weeks prior to slaughter. Thirty min before loading for slaughter, groups of pigs were either mixed with unfamiliar pigs or not mixed. Similarly, on arrival at the abattoir, groups of pigs were either mixed or not mixed. Hence there were four possible treatment combinations: pigs mixed with unfamiliar animals at loading, mixed at unloading, mixed at both points, or pigs which had remained in their social groups for at least 6 weeks prior to slaughter. Carcasses were dressed according to normal practice. After 20 h in the chiller room carcasses were assessed for skin blemish and fibre optic probe (FOP) values were measured in the longissimus dorsi muscle. Mixing pigs at either loading or unloading, or at both points, had no significant effect on the FOP value, but it did have a significant effect on the frequency of skin blemish values. Skin blemish values increased due to mixing at the farm (+0-36, Meat and Livestock Commission scale) however mixing at both places did not have an additive effect. The results indicate that the ideal movement system might be to keep pigs in their farm pen social groups until the point of slaughter.

This experiment was designed to study the effects of stocking density in transit and the use of electric goads on pig welfare and subsequent meat quality. Sixty-four pens, totalling 1400 commercial crossbred hybrid pigs, were transported from a farm to a large commercial abattoir at either high (0·3 m2 per pig) or low (>0·4 m2 per pig) stocking densities. The lorry drivers loaded and unloaded the pens of pigs at either end of their journey with, or without, an electric goad. Similarly, lairage men moved groups of pigs from their lairage pens to the stunning and slaughter area with, or without, goads. Consequently, eight possible treatment combinations arose from this 2 × 2 × 2 factorial experiment. About 20 h after slaughter, the fibre optic probe (FOP) value of the longissimus dorsi muscle was recorded and carcasses were scored for the extent of skin blemish. Pigs in high stocking density groups (HSD) had lower FOP values than those on low stocking density groups (LSD) (P < 0·05) and more severe skin blemish (P < 0·001). The effect of goading in transport or in the lairage, had no significant effect on the FOP values. However, the skin blemish data showed a significant interaction between the use of goads during transport and the stocking density treatment (P < 0·05). This interaction implied that the use of goads when loading pigs at a HSD was associated with a reduction in skin blemish. Conversely, the lowest skin blemish frequency was observed in the LSD treatment group handled without the aid of goads. Pigs in the HSD groups were visibly more skin damaged and exhibited evidence of rectal prolapse which was absent in pigs transported at LSD. Lower stocking densities are to be recommended as carcass, meat quality and pig welfare are probably improved. The use of goads is associated with a higher degree of carcass damage unless pigs are to be densely packed during transport.