Characterizing sow feed intake during lactation to explain litter and subsequent farrowing performance.

Variation in feed intake results in nearly 20% of sows consuming less than the recommended lysine (Lys) intake for lactating sows. The Lys requirement for lactating sows is based on litter size and piglet average daily gain which influences milk production. Litter size continues to increase every year causing the need for routine reevaluation of nutrient requirements. If dietary inclusion levels are not continuously adjusted this can lead to inadequate daily Lys and energy intake and may negatively impact sow body condition and litter performance. The objective was to characterize the average daily feed intake (ADFI) of sows and define feed intake patterns and their effects on sow body weight, farrowing performance, litter performance, and subsequent farrowing performance. ADFI during lactation was recorded for 4,248 sows from 7 independent research studies. Data collection occurred from November 2021 through November 2023 at a commercial breed-to-wean facility in western Illinois. Each sow was categorized as: consistently low intake (< 5.5 kg/d) throughout the lactation (LLL); low intakes (< 5 kg/d) in the first week, then gradually increased throughout the rest of the lactation period (LHH); gradual increase in intake throughout lactation with no drop and a peak intake after day 10 of lactation (gradual); rapid increase in intake with no drop and the peak intake met before day 10 (rapid); a major drop in feed intake (> 1.6 kg decrease for ≥ 2 d) any time during lactation (MAJOR); minor drop (≤ 1.6 kg for ≥ 2 d; MINOR). Sows were also separated into low (quartile 1; ≤ 25%), average (quartile 2 through 3), or high feed intake (quartile 4; ≥ 75%) by parity (P1, P2, P3+). Sows in the LLL category were younger in parity, had the greatest preweaned mortality, weaned the lightest average pigs, and experienced the greatest loss in body weight percentage compared with sows in all other feed intake categories. Furthermore, sows in the LLL and LHH categories had one fewer subsequent pig born compared with sows in the other four categories. These data support historical findings that feed intake patterns directly contribute to current litter farrowing performance. Lactation intake patterns also influence subsequent farrowing performance. Identifying under-consuming sows that are likely Lys and energy deficient allows producers opportunities to promote consistent, adequate daily intakes to these groups and mitigate negative impacts on sow and litter performance.

This study investigated different sow feed intake patterns during lactation and average daily feed intakes within parity on current and subsequent farrowing and litter performance. Findings revealed sows that have consistently low intake throughout the lactation period have a significant reduction in average pig wean weight, a greater percentage of pre-wean mortality, and take an additional day or longer to return to estrus compared with sows that have average or above feed intake throughout the lactation period. Specifically, older parity sows were heavier, had greater feed intake, nursed heavier litters, and had litters with less preweaned mortality compared with younger parity sows. The average pig weaned weight and subsequent total pigs born improved as intake increased within parity. Prewean mortality decreased as feed intake increased within parity. These findings highlight the importance of ensuring sows are not only eating enough, but that they are consuming more than average when possible, to continually improve current and subsequent farrowing and litter performance. This study provides important information that will allow producers to target specific under-consuming sows and then promote consistent and high daily lactation intakes. Targeting these potentially nutrient-restricted sows may help reduce negative impacts on sow and litter performance.

The effect of chronic, non-pathogenic maternal immune activation on offspring postnatal muscle and immune outcomes.

The objective was to determine the effects of maternal inflammation on offspring muscle development and postnatal innate immune response. Sixteen first-parity gilts were randomly allotted to repeated intravenous injections with lipopolysaccharide (LPS; n = 8, treatment code INFLAM) or comparable volume of phosphate buffered saline (CON, n = 8). Injections took place every other day from gestational day (GD) 70 to GD 84 with an initial dose of 10 µg LPS/kg body weight (BW) increasing by 12% each time to prevent endotoxin tolerance. On GD 70, 76, and 84, blood was collected at 0 and 4 h postinjection via jugular or ear venipuncture to determine tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1ß concentrations. After farrowing, litter mortality was recorded, and the pig closest to litter BW average was used for dissection and muscle fiber characterization. On weaning (postnatal day [PND] 21), pigs were weighed individually and 2 barrows closest to litter BW average were selected for another study. The third barrow closest to litter BW average was selected for the postnatal LPS challenge. On PND 52, pigs were given 5 µg LPS/kg BW via intraperitoneal injection, and blood was collected at 0, 4, and 8 h postinjection to determine TNF-α concentration. INFLAM gilt TNF-α concentration increased (P < 0.01) 4 h postinjection compared to 0 h postinjection, while CON gilt TNF-α concentration did not differ between time points. INFLAM gilt IL-6 and IL-1ß concentrations increased (P = 0.03) 4 h postinjection compared to 0 h postinjection on GD 70, but did not differ between time points on GD 76 and 84. There were no differences between INFLAM and CON gilts litter mortality outcomes (P ≥ 0.13), but INFLAM pigs were smaller (P = 0.04) at birth and tended (P = 0.09) to be smaller at weaning. Muscle and organ weights did not differ (P ≥ 0.17) between treatments, with the exception of semitendinosus, which was smaller (P < 0.01) in INFLAM pigs. INFLAM pigs tended (P = 0.06) to have larger type I fibers. INFLAM pig TNF-α concentration did not differ across time, while CON pig TNF-α concentration peaked (P = 0.01) 4 h postinjection. TNF-α concentration did not differ between treatments at 0 and 8 h postinjection, but CON pigs had increased (P = 0.01) TNF-α compared to INFLAM pigs 4 h postinjection. Overall, maternal immune activation did not alter pig muscle development, but resulted in suppressed innate immune activation.

Maternal inflammation or immune activation impacts fetal development and subsequently the offspring's postnatal performance. In particular, maternal immune activation may be detrimental to fetal muscle development and alter postnatal immune responses, both of which are vital in determining livestock efficiency. However, understanding the relationship between maternal immune activation and offspring development is difficult as many models use a live pathogen. This introduces many confounding factors, including increased mortality, persistent postnatal infection, and potential copathogens. Therefore, the objective of this study was to determine the effect of maternal inflammation on offspring muscle development and postnatal inflammatory response using repeated injections of a nonpathogenic immune stimulant. Each injection successfully induced an inflammatory response as indicated by increased rectal temperature and circulating inflammatory markers. The gestational challenge did not result in increased litter mortality. Further, muscle development was not altered in piglets exposed to gestational inflammation. However, when challenged with the same immune stimulant given to the dams, pigs exposed to maternal inflammation had a remarkably suppressed immune response compared to controls. Overall, maternal inflammation independent of infection affected offspring immune function, but not muscle development.