By Abigail Jenkins, Joel DeRouchey, Jordan Gebhardt, Jason Woodworth, Mike Tokach, Robert Goodband, Kansas State University; Joseph Loughmiller and Brian Kremer, Phileo

Yeast products are among those feed additives investigated as there may be an impact on gut health, immune regulation, nutrient digestibility and growth performance. Previous research has demonstrated an improvement in nursery pig growth performance with the inclusion of live yeast in lactation diets but has shown no further improvement in performance with the addition of yeast prebiotics and b-glucans in nursery pig diets.

Live yeast supplementation in gestation and lactation has been shown to increase immunoglobulin A and G concentrations in colostrum and piglet serum at weaning and throughout the nursery period. However, little research has been conducted to determine if supplementation during only lactation can give rise to the same response.

Due to the improvement in immunological criteria found when supplementing live yeast in lactation diets and yeast prebiotics in nursery diets, it was hypothesized that yeast supplementation would improve specific immune response post vaccination. The objective of this study was to determine if yeast supplementation during the lactation and nursery periods would result in improvement in lifetime growth performance, serum antibody titers, and carcass characteristics. 

Animals and treatment structure

A total of 28 mixed-parity sows (DNA 241 DNA; Columbus, Nebraska) were used in a batch farrowing group at the Kansas State University Swine Teaching and Research Center in Manhattan, Kansas. Sows were weighed and moved into the farrowing house on day 110 of gestation. Sows were blocked by parity and body weight and assigned to one of two treatments which consisted of a standard corn-soybean meal diet or a diet that contained the live yeast probiotic, Saccharomyces cerevisiae strain NCYC Sc 47 (0.10% Actisaf Sc 47 HR+; Phileo by Lesaffre, Milwaukee, Wisconsin). Sows were each fed approximately 6 pounds/day of their treatment diet from d 110 until farrowing. After farrowing, sows had ad libitum access to their treatment diet.

After the nursery period, a total of 336 pigs (initially 80.4 ± 10.3 lb) of the original 350 weaned pigs were followed for an additional 94 days until marketing. Two nursery pens of pigs were combined into one finishing pen to create eight or nine replications per treatment with nine or 10 pigs per pen. All pigs were fed a common diet in three phases that were formulated to meet or exceed NRC requirement estimates, throughout the grow-finish period.

Pigs and feeders were weighed at the completion of each phase to determine average daily gain, average daily feed intake and feed to gain ratio. At 165 d of age, final pen weights and individual weights were taken, and pigs were transported to a commercial packing plant (Triumph, St. Joseph, Missouri) for processing and carcass data collection. Data collected included hot carcass weight, backfat thickness, loin depth and percent lean. Carcass yield was calculated as HCW divided by final live weight taken at the farm.

On d 5 post-weaning (22 days of age), one average weight gilt was selected from each pen to be bled. A sample of serum from each female was sent to the Iowa State University Veterinary Diagnostic Laboratory (Ames, Iowa) for porcine circovirus type 2 and Mycoplasma hyopneumoniae antibody analysis. All pigs were vaccinated for PCV2 and Mycoplasma hyopneumoniae (Circumvent PCV-M G2, Merck, Rahway, New Jersey) following the first blood draw. Blood was collected from the same average weight gilts, and the antibody analysis was conducted six more times on d 38, 50, 66, 78, 101 and 162 of life.

At 50 d of age, and at all successive bleeding events, serum was analyzed for the percent inhibition of Lawsonia intracellularis. All pigs were vaccinated for Lawsonia intracellularis (Porcilis Ileitis vaccine, Merck, Rahway, New Jersey) on d 50 following blood collection. Serum samples collected on d 22 and 50 were also used for analysis of immunoglobulin A and immunoglobulin G using an ELISA assay.

Growth performance

The addition of yeast probiotics to the lactation diet that was fed from d 110 of gestation until weaning resulted in no statistical differences (P > 0.100) in sow BW, caliper score or back fat as well as no differences in ADFI or wean to estrus interval. There were no statistical differences (P > 0.100) in litter birth characteristics, litter size or pre-weaning mortality.

During the nursery treatment period, there was a tendency for an interaction between sow and nursery diet for ADG and ADFI (P £ 0.073; Table 1). Numerically, pigs from sows fed Actisaf that were fed either the control or MS309 diets in the nursery, and pigs from control sows that were fed MS309 in the nursery had increased ADG and ADFI when compared to pigs from control sows that were fed the control diet during the nursery treatment period.

At the completion of the nursery treatment period there was an interaction between sow treatment and nursery treatment for BW (P = 0.047). Numerically, pigs from Actisaf sows that were fed the control diet during the nursery period had a heavier BW when compared to pigs from control sows that were fed the control diet during the nursery period. Pairwise comparisons revealed no means separation for BW at the conclusion of the nursery treatment period.

There was a significant main effect of sow treatment on ADG and ADFI in the common nursery period, where pigs from sows fed Actisaf had increased ADG and ADFI when compared to pigs from sows fed the control diet (P < 0.032).

For the overall nursery period, there was an interaction between sow diet and nursery diet for ADG (P = 0.024) where pigs from Actisaf sows fed the control nursery diet performed better than pigs from control sows fed the control nursery diet (P < 0.050), with the other two treatments being intermediate. Pigs from Actisaf sows tended to exhibit improved ADG during the overall nursery period when compared to offspring from control sows (P = 0.073).

There was an interaction between sow and nursery treatments for overall nursery period ADFI (P = 0.048). A numerical increase in ADFI was seen in pigs from Actisaf sows that were fed the control diet during the nursery period compared to pigs from control sows that were on the control diet during the nursery. Pigs from either Actisaf or control sows that were fed MS309 during the nursery treatment period were intermediate. However, pairwise comparisons revealed no means separation between treatments.

At the completion of the finishing period, pigs from Actisaf sows tended to have heavier final BW (P < 0.067) and HCW (P = 0.101) when compared to pigs from control sows. There were no main effects of sow treatment or nursery treatment as well as no interactions between the two on overall finishing period growth performance (P > 0.100).

There was an interaction between sow and nursery diets on backfat depth at harvest (P = 0.034). Numerically, pigs from Actisaf sows that were fed the control nursery diet had decreased backfat depth compared to pigs from control sows that were fed the control nursery diet, or pigs from Actisaf sows that were fed MS309 during the nursery treatment period. However, pairwise comparisons revealed no means separation between the treatments.

Antibody titers, immunoglobulin concentrations

Immunoglobulins are antibodies found that can be passively acquired through the ingestion of colostrum and milk, or actively produced in response to disease challenge or vaccination. Thus, a higher immunoglobulin concentration is indicative of a more robust immune system. There were no sow diet or nursery diet effects on log₁₀ immunoglobulin G concentrations on d 22 or 50 of age, as well as no significant second or third order interactions (P > 0.100; Figure 1). For log₁₀ IgA concentration, there was an interaction between sow and nursery diet (P = 0.029; Figure 2).

Pigs from Actisaf sows tended to have decreased log₁₀ IgA concentration when they were fed MS309 during the nursery treatment period, when compared to those fed the control diet during the nursery period (P = 0.051). There was a significant day effect on both IgG and IgA concentrations, where IgG concentration was lower at 50 d of age and IgA concentration was higher at 50 d of age as compared to concentrations at 22 d of age (P < 0.001).

There was a nursery diet × day interaction for porcine circovirus type 2 (PCV2) S/P ratio (P = 0.036; Figure 3). Pigs fed MS309 tended to have a higher PCV2 S/P ratio at 22 d of age (P = 0.050). However, at d 66, 78, and 162 of age, pigs fed MS309 during the nursery period had lower PCV2 S/P ratios than pigs fed the control diet during the nursery period (P £ 0.022) and tended to have lower PCV2 S/P ratios on d 50 and 101 of age (P < 0.093). There was a tendency for a sow diet × day interaction for the PCV2 S/P ratio (P = 0.097; Figure 4).

Pigs from Actisaf sows had a higher PCV2 S/P ratio at 101 d of age when compared to pigs from sows fed the control diet (P = 0.046), with no evidence of a difference at all other sampling points. There was a tendency for a sow diet × nursery diet interaction on Lawsonia intracellularis inhibition (P = 0.071; Figure 5).

Pigs from Actisaf sows that were fed the control diet in the nursery had numerically the highest percentage inhibition on d 66, 78, 101, and 162. However, pairwise comparisons revealed no means separation within day of serum collection.

For both antibody titers and Lawsonia intracellularis inhibition, there was a significant day effect (P < 0.001). For Lawsonia intracellularis, percentage inhibition rose drastically after vaccination on d 50 of age until d 78 of age, following which, the percent inhibition began to plateau. Mycoplasma hyopneumoniae S/P ratio peaked at d 22 of age, then following vaccination, the S/P ratios dropped until d 38 and then began to rise until d 78 of age, after which the S/P ratios decreased once more until marketing. Porcine circovirus type 2 S/P ratios decreased following vaccination until d 38 of age, after which the S/P ratios rose until d 66 of age and then began to decrease until marketing.

In conclusion, there were no effects of added live yeast in the lactation diet on lactation performance. However, pigs fed the control diet during the nursery period tended to have improved ADG during the overall nursery period if they were from sows fed Actisaf, compared to offspring from control sows.

Conversely, there was no difference based on lactation diet in nursery ADG for pigs fed MS309. While sow diet x day and nursery diet x day interactions were observed in antibody titer analysis, the overall impact of yeast probiotics in sow lactation diets and yeast prebiotics in the nursery diet was minimal. There were no differences in overall finishing growth performance with the inclusion of live yeast in lactation diets or yeast prebiotics in nursery diets; however, pigs from Actisaf sows tended to have a higher final BW and numerically higher HCW.