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The objective of the present study was to assess the effects of a dietary supplement of active dry yeast (strain NCYC Sc47) on CD4+ and CD8+ lymphocyte subpopulations and on total fecal coliform counts in nursery pigs.
A total of 48 crossbred male (noncastrated) nursery pigs (Duroc-Landrace reciprocal breeding) were received at 21 days of age. Animals were allowed a 2-week acclimatization period to establish adequate intake of dry feed, which was a conventional lactose-rich starter diet. Previous to their arrival, pigs had never received feed additives, eg, prebiotics, probiotics, or antibiotics. On Day 0 of the study (at 35 days of age), pigs received either the basal diet (Control group) or the same diet supplemented with Sc47 (Sc47 group). Initial average weights were 11.87 kg and 11.71 kg in the Sc47 and Control groups, respectively. Individual health status of the pigs was assessed by physical appearance, average daily gain (ADG), and average body weight (BW). Pigs were individually weighed at weekly intervals, on the days when samples were collected. Blood and individual fecal samples were collected from all pigs on Days 0, 7, 14, 21, 28, 35, and 42 of the experiment. Subpopulation proportions of T lymphocytes (CD4+, CD8+, and CD4+CD8+) were analyzed by flow cytometry, and fecal coliform counts were performed.
The ranges for the lymphocyte subpopulations in counted cells were CD4+, 928 to 1615; CD4+CD8+, 505 to 847; and CD8+, 938 to 1441, in a total of 10,000 cells examined by flow cytometry (Table 3). Weekly average values for the Sc47 group were higher than those of the Control group on Days 7, 14, 21, 35, and 42 for lymphocyte subsets CD4+ and CD8+, and on Days 7, 14, and 21 for CD4+CD8+. Additionally, total average values were higher for Sc47 than for the Control group for all three lymphocyte subsets (P < .05). At Day 0, the log10 transformed coliform counts did not differ between treatment groups. Values increased in both groups until Day 14, then colony counts decreased in both groups. Except for Day 0, coliform colony numbers were numerically lower for the Sc47 group in all weeks. Colony counts differed significantly between treatment groups on Days 7, 28, 35, and 42, but not on Days 0, 14, or 21.
This study shows two pathways through which Sc47 may have a positive influence on pig health. Under the conditions of this study, numbers of peripheral blood T-lymphocytes increase when Sc47 is included in the feed of nursery pigs, which may have a positive impact on animal health. Additionally, reduction of intestinal coliform numbers in nursery pigs receiving active dry yeast contributes to improving intestinal health and therefore to explaining why yeast as a feed additive may contribute to reducing the use of antibiotics as growth promoters or therapeutic agents.
Monroy-Salazar HG, Pérez-Sotelo L, González-Hernández Y, et al. Effects of a live yeast dietary supplement on fecal coliform counts and on peripheral blood CD4+ and CD8+ lymphocyte subpopulations in nursery pigs. J Swine Health Prod. 2012;20(6):276–282.