Impacts of a modified farrowing pen design on sow and litter performances and air quality during two seasons

The impacts of using a modified farrowing pen (MOD) on the performance of sows and their litters and on ambient air quality over a hot and a cool season were evaluated. Primiparous Yorkshire × Landrace sows farrowed either during the months of February and March (thermoneutralily, TN) or June and July (heat-stress, HS). Temperatures within each season were controlled to 21 and 29 °C, respectively, for TN and HS. Animals from each group were assigned to a standard farrowing crate (STD; TN, n = 17; HS, n = 16) or a MOD pen (TN, n = 19; HS, n = 19). The MOD pen consisted of a STD crate with a 1.5 × 1.6-m comfort zone in the back, equipped with rubber floor mats, a feeder and a nipple waterer. Litter size was standardized to 10 or 11. No creep feed was provided and piglets were weighed weekly. Sows were weighed on days 2 and 22. Feed intake of sows was monitored daily, a milk sample was obtained on day 21 for compositional analyses and jugular blood samples were collected on days 2 and 21 to measure prolactin, IGF-I and urea. Sows consumed less feed (3.4 vs. 4.7 ± 0.1 kg/day, P < 0.001) in a hot than in a cool season and, at 29 °C, sows in MOD pens consumed more feed (3.9 vs. 3.0 ± 0.2 kg/day, P < 0.01) than sows in STD pens. Sow lactation weight loss was greater (− 26.4 vs. − 19.1 ± 1.9 kg, P < 0.05) for sows in STD than MOD pens in a hot season. The reduction in prolactin concentrations from days 2 to 22 of lactation tended to be greater (P = 0.08) in a hot season for sows in STD pens. Concentrations of urea and IGF-I increased as lactation advanced (P < 0.01) and IGF-I was lower for HS compared to TN sows on both days (P < 0.01), whereas urea was greater for HS sows on day 2 only (P < 0.01). Milk DM was less in a hot than in a cool season (P < 0.01). Average piglet weight gain was reduced in a hot compared to a cool season during the second week of lactation (P < 0.05) and this reduction was less in MOD than STD pens during the third week of lactation (P < 0.01). During a hot season, even though not significant, average weight gain of piglets from days 2 to 21 of lactation was reduced by 6.0% in MOD pens compared to 9.7% in STD pens.