Identifying and optimizing housing and management systems that improve the well-being of the gestating sow is essential to sustaining animal agriculture. Therefore, the impact of 2 floor-space allowances and a high-fiber gestation diet on dry group-housed sows were evaluated using multiple measures of well-being. Groups of 10 multiparous sows/pen (n = 221) were assigned randomly to treatments in a 2 × 2 factorial arrangement to either a corn-soybean meal diet (CTL) or corn-soybean meal diet supplemented with soybean hulls and wheat middlings (FBR), and floor-space allowance of either 1.7 or 2.3 m(2)/sow. Sow BW, backfat (BF), and body condition score (BCS) were all recorded on d 34, 65, 90, and 110 of gestation, whereas skin lesions were scored on d 34, every 2 d for the first 2-wk postmixing, and then biweekly throughout gestation. Blood sample was collected only on d 34 for cortisol (baseline), and samples were collected on d 90 of gestation for other measures including cortisol. Behavior was registered on multiple days throughout gestation. Sows fed FBR and kept at 1.7 m(2) produced heavier litter and weaning weights and greater number of piglets born alive, compared to sows fed FBR but kept at 2.3 m(2) of floor space (diet × floor space, P ≤ 0.04). Sows fed FBR and kept at 1.7 m(2) performed fewer oral-nasal-facial and sham-chew behaviors than sows fed CTL and kept at the same floor space (diet × floor space, P ≤ 0.044). Sows kept at 1.7 m(2) of floor space had a greater (P < 0.05) total lesion severity score than sows kept at 2.3 m(2)/sow, and vulva lesion scores were more (P < 0.02) severe among CTL-fed sows than FBR-fed sows. Parities 2 and 3 sows fed FBR and kept at 1.7 m(2) of floor space were heavier (P < 0.001) than sows fed the same diet but kept at 2.3 m(2). These results indicate that keeping small groups of pregnant sows at a minimum floor-space allowance of 1.7 m(2)/sow and floor feeding these sows a high-fiber diet can improve short-term sow well-being.

The objective of this study was to determine the effect of ad libitum feeding diets differing in standard ileal digestible (SID) lysine and ME concentrations that bracket those fed to developing gilts in U.S. commercial settings. Average SID lysine and ME concentrations in diets currently fed to developing gilts were obtained from a poll of the U.S. commercial swine industry. Crossbred Large White × Landrace gilts (n = 1,221), housed in groups, were randomly allotted to 6 corn-soybean diets in a 2 × 3 factorial arrangement formulated to provided 2 SID lysine and 3 ME concentrations. Gilts received grower diets formulated to provide 1.02% (control = survey average) or 0.86% (control minus 15%) SID lysine and 2.94, 3.25, or 3.57 (survey average ME ± 10%) Mcal of ME/kg from 100 d of age until approximately 90 kg BW. Then, gilts were fed finisher diet containing 0.85% (control = survey average) or 0.73% (control minus 15%) SID lysine and 2.94, 3.26, or 3.59 (control ± 10%) Mcal of ME/kg until 260 d of age. Gilts were weighed, and backfat thickness and loin muscle area were recorded at the beginning of the trial and then every 28 d. Starting at 160 d of age, gilts were exposed daily to vasectomized boars and observed for behavioral estrus. At approximately 260 d of age, gilts were slaughtered and their reproductive tract was collected. Each reproductive tract was examined to determine whether the gilt was cyclic, the stage of estrus cycle, ovulation rate, and uterine length. Data were evaluated for normality and analyzed using mixed model methods. Average age at puberty was 193 d of age with a range from 160 to 265 d. When all gilts on trial at 160 d of age were included in the analysis, 91.0% reached puberty as determine by observation of standing estrus. Differences between dietary treatments on age at puberty or measurements of the reproductive tract were not detected. Growth rates to 160 d were not limiting for attainment of puberty in response to daily boar stimulation from 160 d.

An accurate understanding of heat stress (HS) temperatures and phenotypes that indicate HS tolerance is necessary to improve swine HS resilience. Therefore, the study objectives were 1) to identify phenotypes indicative of HS tolerance, and 2) to determine moderate and severe HS threshold temperatures in lactating sows. Multiparous (4.10 ± 1.48) lactating sows and their litters (11.10 ± 2.33 piglets/litter) were housed in naturally ventilated (n = 1,015) or mechanically ventilated (n = 630) barns at a commercial sow farm in Maple Hill, NC USA between June 9 and July 24, 2021. In-barn dry bulb temperatures (TDB) and relative humidity were continuously recorded for naturally ventilated (26.38 ± 1.21°C and 83.38 ± 5.40%, respectively) and mechanically ventilated (26.91 ± 1.80°C and 77.13 ± 7.06%, respectively) barns using data recorders. Sows were phenotyped between lactation d 11.28 ± 3.08 and 14.25 ± 3.26. Thermoregulatory measures were obtained daily at 0800, 1200, 1600, and 2000 h and included respiration rate, and ear, shoulder, rump, and tail skin temperatures. Vaginal temperatures (TV) were recorded in 10 min intervals using data recorders. Anatomical characteristics were recorded, including ear area and length, visual and caliper-assessed body condition scores, and a visually assessed and subjective hair density score. Data were analyzed using PROC MIXED to evaluate the temporal pattern of thermoregulatory responses, phenotype correlations were based on mixed model analyses, and moderate and severe HS inflection points were established by fitting TV as the dependent variable in a cubic function against TDB. Statistical analyses were conducted separately for sows housed in mechanically or naturally ventilated barns because the sow groups were not housed in each facility type simultaneously. The temporal pattern of thermoregulatory responses was similar for naturally and mechanically ventilated barns and several thermoregulatory and anatomical measures were significantly correlated with one another (P &lt; 0.05), including all anatomical measures as well as skin temperatures, respiration rates, and TV. For sows housed in naturally and mechanically ventilated facilities, moderate HS threshold TDB were 27.36 and 26.69°C, respectively, and severe HS threshold TDB were 29.45 and 30.60°C, respectively. In summary, this study provides new information on the variability of HS tolerance phenotypes and environmental conditions that constitute HS in commercially housed lactating sows.

Different floor space allowances for dry, pregnant sows in pens were evaluated to determine the impacts of space on sow behavior, immune, and cortisol measures. The experiment consisted of 6 replications (blocks 1 to 6; n = 20 sows/group), and within each replicate, physiological measurements were recorded for 2 consecutive pregnancies. A total of 152 sows were measured at 1 gestation, and 65 of those sows were measured at the successive gestation (n = 217). Groups of 5 sows/pen were assigned to 1.4, 2.3, or 3.3 m(2) of floor space/sow or of 5 sows in individual stalls (1.34 m(2)). Behavior measures were stand, sit, lie, walk, drink, oral-nasal-facial (ONF), sham chew, and aggression. Immune traits included both descriptive and functional aspects and cortisol. At d 90 ± 5 of gestation, the occurrence of ONF behaviors increased from 0300 to 1500 h, and lying behavior decreased from 0700 to 1100 h for sows kept at 2.3 m(2). Sows in stalls displayed more (P < 0.05) ONF from 1500 to 2300 h. Stand, sit, drink, ONF, and sham-chew behaviors were affected by floor space; sows in pens at 2.3 m(2) performed more ONF, and sows at 1.4 m(2) performed more sham chewing (P < 0.05). Standing (P = 0.05) and drinking (P = 0.06) were increased, but lying (P = 0.06) was reduced for sows in pens at 2.3 or 3.3 m(2). Sitting and drinking were greater but lying was less for sows in stalls compared with sows in pens (P < 0.01). Immune traits were affected by treatment (P < 0.05); neutrophils were less and lymphocytes were greater, resulting in a reduced neutrophil:lymphocyte (N:L) ratio (P < 0.05) for sows in pens at 3.3 m(2). Natural killer cell was greater but lymphocyte proliferation was less for sows in pens at 1.4 m(2) (P < 0.05). Sows in stalls had greater N:L ratio than sows in pens (P < 0.05). For sows in pens, linear and quadratic responses were detected for behavior and immune traits. As floor space increased, walking and aggression increased. As floor space decreased, neutrophils, N:L, and natural killer cell increased, but as floor space increased lymphocyte proliferation increased. On the basis of behavioral and physiological responses shown by sows in all 4 environments it is apparent that neither floor space nor stall environment provided adequate or quality of space to improve sow well-being. However, the differential behavioral and physiological mechanisms initiated by sows in response to their specific environment the sows were able to evoke the appropriate response(s) needed to adequately adapt to their environment.