A major public issue on a global scale is farm animal welfare; with the most critical issue facing the swine industry being how the pregnant sow should be kept in commercial pork production. Despite the successful passing of state-by-state referendum by HSUS, that keeping sows in group-pens is a welfare-friendly practice and state, the reality is that group-penned sows experience “new problems” that adversely affect their welfare. Therefore, the objectives of this study were to evaluate the effects of feeding dietary-fiber to gestating sows kept in group-pens (10 sows per pen) at different floor-space allowances on sow performance, productivity, immune and endocrine status, and behavior. In this study, 240 sows were allotted to a dietary treatment of either a) standard diet (control) or b) standard diet supplemented with high-fiber (treatment) and a floor-space allowance treatment of either 1.7 m2 or 2.3 m2 per sow. The high-fiber diet used in this study consisted of 15% wheat middlings and 30% soy hulls. Performance measures included sow body weight, backfat (10th rib), and body condition and lesion severity scores were assessed throughout gestation. Sow productivity was assessed using “standard” farrowing measures. Sow well-being was further assessed using various welfare measures which encompassed immune, endocrine and behavior traits, these measures were taken throughout gestation. Data were analyzed using Proc MIXED with repeated measures and Chi-square analysis (SAS).
Both diet and floor-space allowance had an impact on sow well-being, and there were diet x floor-space interaction for some of these measures. In short, sows fed high-fiber diet performed better than did sows fed control diet; sows fed high-fiber diet gained more body weight, were heavier overall, and had greater body conditions scores throughout gestation than did sows fed control diet. Sows fed control diet tended to retain more piglets than did sows fed a high-fiber diet. In some cases, immune status for sows fed high-fiber diet was enhanced compared with sows fed control diet, with one exception, neutrophil phagocytosis. Neutrophil phagocytosis and plasma cortisol were greater for sows fed control diet. Diet had an impact on sow behavior; with those sows being fed a control diet having longer and more stand bouts and more oral-nasal-facial bouts compared with those sows fed high-fiber diet. In general, sows fed control diet were more active. Frequencies of eat and drink bouts were greater amongst sows fed high-fiber diet. Floor-space allowance affected sow lesion scores and other behaviors. Sows kept in pens at 1.7 m2 had greater lesion severity scores than did sows kept in pens at 2.3 m2; while aggression, sham-chew, and drink behaviors were all greater amongst sows kept in pens at 2.3 m2 compared to sows kept in pens at 1.7 m2. However, stand behavior and overall activity were greater amongst sows kept in pens at 1.7 m2 than for sows kept at 2.3 m2. Sows fed high-fiber diet and kept in pens at 2.3 m2 performed less oral-nasal-facial behaviors compared with all other treatment groups. Sows fed control diet and kept at 2.3 m2 floor-space had heavier litters than did sows from other treatment groups.
Taken together these data imply that both type of diet and floor-space allowance can positively impact sow performance, behavior and immune status during gestation, but this group system and management scheme are not optimized due to some apparent “negative” affects on sow welfare that still are apparent within this system, thus others factors still need to be assessed and optimized. For example, aggressive encounters were common within this system especially around feeding time, and thus this may have diluted the “positive” effects and/or contributed to the ‘negative” effects found within this housing environment based on animal welfare. Thus, it is speculated that reducing aggressive encounters by providing protection during feeding (e.g., feeding stall) may further improve well-being, especially by reducing lesion severity scores within this system. When implementing a group-pen system and using floor-feeding, feeding sows a high-fiber diet can improve sow performance (body weight, body weight gain and body condition scores) and motivate sows to utilize their natural sequence of important maintenance behaviors such as the eat-drink-eat sequence. However, type of diet and floor-space allowance are not the only components of a group-housing system that must be considered but group-size can also impact the well-being of the gestating sow. For example, floor-space allowance can impact lesion severity and maintenance behaviors, but the floor-spaces used in this study did not necessarily improve sow well-being nor negatively impact sow well-being. However, we have shown that 1.7 m2 of floor-space is not detrimental to sow well-being and in fact, if other components are considered this may be more ideal than 2.3 m2 of floor-space. Results herein indicate that individual components of a sow housing system (such as diet) can impact sow well-being and therefore these factors and others should be assessed further in order to determine an optimized system that truly improves sow well-being.
