The welfare and productivity of dry sows in different group housing systems in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North, New Zealand
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This research aimed to take a holistic approach to assessing dry sow welfare in relation to gestation accommodation. Multiple factors that affect the welfare of a sow were considered. In addition, the multitude of systems in New Zealand that are used to accommodate dry sows in groups were captured. Commercial pig farms (n=20 farms, 7,912 sows total) were chosen to represent the spectrum of different layouts and management practices in order to obtain data from a wide range of different systems. During each on-farm visit, data concerning housing, management, sow behaviour, welfare and productivity were collected. A number of criteria were used to describe the farms (group size, stall duration, presence of bedding, feeding method, feeding frequency). Sows kept in stalls for more than 5 weeks (n = 3 farms) had significantly higher injury scores than sows that were in stalls for a shorter length of time or sows that were not kept in stalls for any period during mating or pregnancy. Sows fed twice daily had significantly higher stereotypies (P<0.05) than those fed at a different frequency. A welfare index (WI) was calculated for each farm. This index incorporated each farm‟s total scores for injuries, stereotypies, coat condition, soiling and lameness. A low WI represented a lower presence of indicators that were associated with compromises to welfare. Hence, a low WI represented good welfare. For each farm, the minimum possible WI was 0.33, whilst the maximum possible WI was 5.0. The mean WI was 0.65 (±0.14 SD). Overall, there was not a high prevalence of indicators of compromised welfare. Out of the 20 farms, with an average herd size of 395.60 sows per farm; only 10 sows in total were lame. Only three farms had sows with a coat condition score above 0 (normal). There was no difference between mean piglets born alive per litter (BA) for stalls (12.65±0.36) vs. group housed sows for the entire gestation (12.27 ± 0.43) , or for the number of piglets weaned per sow per year (stalls: 23.70±0.59 W/S/Y, groups: 24.92±1.23 W/S/Y). As a result of this study, it is clear that there is no perfect or ideal system for keeping dry sows, because a sow‟s needs change throughout different stages of the production cycle. Therefore the implication is that in any housing system, both the advantages and disadvantages relating to a sow‟s welfare will also change over time. In light of this, operators need to understand the variation both between and within systems and how best to manage them.
Sows, Housing, Swine, Pigs, Group housing, New Zealand