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EFFECTS OF SOW GUT MODIFYING FEED ADDITIVES ON REPRODUCTIVE CHARACTERISTICS AND PROGENY GROWTH PERFORMANCE
Providing wholesome pork products to consumers involves raising healthy pigs to grow well and be feed efficient from birth to market. Raising these pigs starts with ensuring the sow is healthy and provided good nutrition in gestation and lactation. Therefore, this dissertation primarily focuses on research of gut modifying feed additives fed to sows in gestation and lactation (and to their progeny in Chapter 3) to enhance reproductive performance and litter growth to weaning (and in the nursery). In Chapter 2, a total of 606 sows and their progeny were used to determine if feeding gestating and lactating sows a proprietary strain of Pichia guilliermondi as a whole-cell inactivated yeast product (WCY; CitriStim, ADM Animal Nutrition, Quincy, IL) improves sow and litter performance in a commercial production system. Sows were fed a control (CON) diet or control diet fortified with 0.15% of the WCY from d 35 of gestation through lactation. Sows supplemented with WCY in gestation and lactation had a greater number of total born piglets by 0.45 pigs (P < 0.04), piglets born alive (P < 0.04), heavier born alive litter weights (P < 0.001), and greater post cross-foster litter size (P < 0.001) compared to CON fed sows. Litter size at weaning was increased by 0.54 pigs when sows were fed WCY compared to CON (P < 0.001). However, litter weaning weights and 21-day adjusted litter weaning weights were similar (P > 0.158) with the 21-day adjusted litter weaning weights being numerically greater for the WCY sows. The average piglet weaning weights from CON fed sows were heavier by 0.35 kg compared to WCY (P < 0.001). This increase in body weight of piglets from CON fed sows is partially explained by their 0.93 days longer lactation (P < 0.001) and may also be due to the smaller litter size nursed throughout lactation. The percent of litters treated for scours decreased from 38.3% to 14.2% when sows were fed WCY (P < 0.001). The distribution of birth and weaning weights was not different (P > 0.2461) between treatments.
Chapter 3 encompasses a sow experiment where progeny were followed onto the nursery for a 28-d study. Forty-seven sows and their progeny were used to determine if feeding gestating and lactating sows a Bacillus licheniformis direct-fed microbial (DFM), an organic acid blend of medium and short-chain fatty acids (OA), or in combination improves sow lactation feed and water intake, litter growth, and subsequent reproductive performance. At weaning, offspring were fed a positive control diet (PC), negative control diet (NC), or a diet representative of their dam’s treatment to determine if there is an additive benefit to also feeding DFM and/or OA to nursery pigs in addition to their dams. On approximately d 80 of gestation, sows were fed one of four diets in a 2 2 factorial design: 1) gestation control (CON), 2) CON with DFM (1.6x109 CFU/kg of complete feed), 3) CON with 0.4% OA, 4) CON with both DFM and OA. Dietary treatments were also fed throughout lactation. Sows fed the OA diets had fewer mummies per litter (P < 0.010) compared to diets not containing OA. Sows fed diets with the DFM gave birth to lighter pigs born alive (1.5 vs. 1.7 kg; P < 0.003) compared to non-DFM fed sows, and a tendency for an interaction (P < 0.092) existed where feeding DFM+OA lessened the decrease in born alive BW. There was a tendency (P < 0.093) for pigs from DFM fed sows to also be lighter at weaning (5.8 vs. 6.2 kg) compared to pigs from sows not fed DFM, with no differences in litter sizes at weaning (P < 0.815). There was a tendency (P < 0.079) for the DFM to decrease the amount of sow BW loss in lactation compared to sows not fed the DFM (approximately 6 vs. 8% BW loss, respectively). The maintained BW in lactation was likely related to DFM sows numerically (P < 0.124) consuming 8.4% more feed during d 7-14 of lactation and 6.4% more feed (P < 0.234) from d 1 of lactation to weaning. The interaction was approaching a trend (P < 0.133) where sows fed DFM returned to estrus 1.0 day sooner than CON, but only 0.4 days sooner when sows were fed the DFM+OA diet.
Progeny weaned from these sows (n = 384, Initial BW = 6.15 kg) were blocked by initial BW and sex and allotted (6 pigs/pen, 8 pens/treatment) to one of 8 nursery treatments. Pigs from CON sows were fed a negative (NC; no antibiotics, no pharmacological Zn or Cu) or positive (PC; neomycin-oxytetracycline in phases 1 and 2 (827 and 551 ppm) and carbadox in phases 3 and 4 (55 ppm)) control diet. Pigs from sows fed DFM, OA, or DFM+OA were fed the NC diet or a diet representative of their dam’s treatment. Diets with DFM contained 1.6x109 CFU/kg of complete feed and diets with OA contained 0.5, 0.4, 0.3, and 0.0% OA in phases 1-4, respectively. Weaning weight was used as a covariate for nursery performance due to the DFM offspring being significantly lighter at weaning. For all phases and overall, PC fed pigs had greater ADG (P < 0.003) and ADFI (P < 0.059) than NC pigs. PC fed pigs had greater G:F (P < 0.010) than NC pigs for all phases and overall except d 21-28 (P < 0.532). Feeding DFM or OA in sow diets improved (interaction; P < 0.049) nursery pig G:F, but DFM+OA offspring had similar G:F compared to NC pigs from CON fed sows for d 7-14, 0-14, 0-21, and 0-28. Feeding DFM or OA to sows and their progeny decreased ADFI (interaction; P < 0.042) but improved G:F (interaction; P < 0.028) for d 7-14 and 0-14 with DFM+OA having similar performance to NC. For d 14-21 and 0-21, feeding DFM or OA to sows and their progeny decreased ADFI whereas DFM+OA increased ADFI above NC (interaction; P < 0.019). Overall, d 0-28, feeding DFM or OA to sows and their progeny improved G:F (interaction; P < 0.001) with DFM+OA having poorer G:F compared to NC. When the DFM was fed to sows and nursery pigs, progeny harvested on d 6 post-weaning had a decreased ratio of villus height to crypt depth (P < 0.035) compared to sows and pigs not consuming the DFM (average 1.34 vs. 1.67). Comparing pigs fed PC vs. NC from CON fed sows, expression of interleukin 10 (IL-10) was greater (0.51-fold increase; P < 0.046) for NC pigs than PC pigs. Expression of occludin (OCLN) was lower (P < 0.010) when OA was fed to the sows and pigs compared to when OA was not fed to the sows and pigs (0.78 vs. 1.00, respectively).
Chapter 4 is the only chapter that does not include maternal nutrition. In this chapter, maternal line gilts (Topigs Norsvin TN70) were bred with frozen semen from Duroc boars born from 2000 to 2017 divided into two genetic groups: semen from boars born in 2000 to 2005 and 2011 to 2017. These genetic groups had vastly different terminal sire indexes (TSI) of 88.2 and 112.0 for 2000 to 2005 and 2011 to 2017, respectively. A total of 155 pigs were weaned into 44 pens in a wean-to-finish facility to determine if genetics from two decades of sires and sex of the progeny impact progeny growth performance and carcass characteristics. The expected large growth performance differences indicated by the TSI’s of the two genetic groups were not observed. However, barrows had greater feed intake (P < 0.031) and fatter carcasses (P < 0.004) than the more feed efficient (P < 0.006) and leaner (P < 0.015) gilts in this study. Modern swine genetics have been selected to be leaner and results from this study agree, although the differences in live scan and carcass measurements were not as large as expected. The lack of differences between genetic groups could possibly be due to environmental differences including nutrition and rearing conditions from when these sires were alive compared to what was experienced by these progeny.
In conclusion, feeding gestating and lactating sows a proprietary strain of Pichia guilliermondi as a whole-cell inactivated yeast product increased the number of piglets born and weaned as well as decreased the prevalence of scours during lactation. Feeding a Bacillus licheniformis DFM to sows may decrease pig born alive weight and subsequent weaning weight but reduce sow BW loss through 6.4% more lactation feed intake, quickening the return to estrus. Other than decreasing the number of mummies per litter, feeding the OA alone or in combination did not improve sow reproductive or litter growth performance in this study. Feeding DFM or OA to sows or their offspring may improve nursery feed efficiency but did not result in a difference in ADG or final BW in this study. Feeding the combination diet (DFM+OA) to the sow and nursery pigs tended to increase ADFI. Feeding antibiotics post-weaning continued to improve pig growth performance resulting in 2.7 kg heavier pigs at the end of the 28-d nursery period. Lastly, the expected large growth performance differences indicated by the TSI’s of two genetic groups created by using frozen semen from boars born in 2000 to 2005 and 2011 to 2017 were not observed.