Supplementation of piglet feeds with hydrolyzed brewery yeast (Progut ) has given valuable benefits in piglet production At weaning, piglets have to adapt rapidly to major changes in their nutrition and environment. It's a stressful situation at a time when the immune status of a piglet is at its lowest. Feed intake remains low for several days after weaning and the weaning transition is also accompanied by adverse changes in intestinal morphology (Bruininx et al 2002). Therefore, piglets are susceptible to post-weaning diarrhea which is usually linked to E.coli infections. In addition to satisfying the nutritional requirements of a weaned piglet, the feed industry has the challenge to formulate diets that would prevent the growth of E.coli, stabilize gut microbiota, improve the function of immunity and enhance disease resistance in young piglets. Antibiotic growth promoters (AGP) have been used to overcome this problem. The European ban on the use of AGP s which is due to be implemented at the start of the New Year as well as increasing pressure to decrease or discontinue their use elsewhere has lead to the increase in demand for alternative methods. Several new products have been investigated and proposed as alternatives to AGP s (Berg, 1998, Close 2000, Turner et al. 2001). The addition of both live and inactivated yeast products have gained growing interest during the last few years. There are however, major differences in the strains, composition and structure of the yeast products and as a consequence, their effect on animal health and productivity. The effects of yeast products are dependent on the method of processing The yeast cell wall consists of long polysaccharide chains and is considerably resistant to digestion. Hydrolysis is needed to break down the cell wall structures and to activate some of the yeast functions. The methods and conditions of the processing affect the degree of hydrolysis and the efficiency of the end product. Therefore, the capability of a yeast product to prevent the attachment of E.coli or the stimulation of immunity is closely related to the hydrolysis process (Vuorenmaa 2004). The combination of yeast extract and cell wall appears to be more efficient than cell wall alone. In a trial conducted at Justus-Liebig University, Giessen, the capability of several yeast products in binding enterotoxic E.coli strains with different fimbria types was studied. Various yeast products were co-incubated with E.coli bacteria at 37 o C and after one hour the suspension was centrifuged and the number of unbound bacteria in the supernatant was determined. The E.coli count with hydrolyzed brewery yeast (Progut TM ) was in every case the lowest, showing that all the E.coli strains that were studied attached most significantly to it (Bauerfeind et al. 2004). In most cases, the difference to other yeast products was also significant (<0,029). It was suggested that the special characteristics of hydrolyzed brewery yeast (Progut TM ) were related to its patented production process. The results from the study with F4-ETEC E.coli are presented as an example in figure 1. It should be noted that, compared with the cultures, most of the yeasts reduced the germ counts with F4-ETEC and F4/F6 ETEC strains but not with any of the other strains.
An in vitro trial using the Ussing chamber system at Hannover Veterinary High School indicated that the hydrolyzed brewery yeast (Progut ) was capable to protect gut tissue from an E.coli infection while a competitive yeast cell wall product had no effect at all (Breves 2004). A further in vivo trial with E.coli challenged piglets resulted in a similar kind of findings. In addition to its effects on E.coli attachment, the hydrolyzed brewery yeast product (Progut ) has also shown to support natural immunity in the gut (Rautonen and Apajalahti 2002), increase the relation of Bifidobacteria to Enterobacteria and stabilize gut micro-flora during critical production periods (Vaahtovuo et al. 2005). Subsequently, these functions have shown to have beneficial effects on piglet post-weaning performance in large number of Research Institute trials. Two of these trials are presented in the following text. In a Danish Institute trial, feeds containing hydrolyzed brewery yeast (Progut ) reduced the risk of diarrhoea and improved feed conversion of piglets The effect of hydrolyzed brewery yeast product (PG) on post-weaning diarrhoea, weight gain and feed conversion with piglets was measured in a trial conducted at The Danish Institute of Agricultural Science (Foulum) 2004. The study included 10 replications of 3 individually housed sows and their litters randomly assigned to one of three treatment groups. 1) PG for sow and piglets (PSP), 2) PG for piglets only (PP) and 3) Control (C) without any feed enhancers. The piglets were weaned at 4 weeks of age. In the PSP group, 0,15 % of PG was added in the sow feed from one week before expected farrowing and during lactation. In the PSP and PP groups, the piglets were offered a weaning feed containing 0.3% PG from two weeks of age until 2 weeks post weaning, and a starter feed containing 0,2 % PG from 2 weeks post weaning until 5 weeks post weaning. Treatment group C was subjected to the same feeding regime but without any feed enhancer. Two piglets from each litter were individually housed after weaning. One of these piglets was challenged on days 1, 2 and 3 after weaning with 10 8 cfu E. coli O149:F4ac,STb, LT, EAST1, while the other piglet was given a placebo treatment. Three piglets per litter were group housed and performance and diarrhoea were monitored from weaning and until 5 weeks after weaning. The addition of the hydrolyzed brewery yeast product (PG) in the feed significantly lowered diarrhoea scores (F 2,17 =9.16; P<0.01) on days 2-6 after weaning compared to piglets (figure 2). The effect was evident in both the piglets and in E.coli challenged piglets (Jensen et al 2005). The piglets that had diarrhoea scores over 3 were regarded as having clinical diarrhoea. These piglets were given a daily index 1 and healthy piglets were given an index 0. When calculating an average for diarrhoea days in different treatments a significant reduction of diarrhoea days can be seen in PG groups compared with group (figure 3). Piglets in the PSP group had 1/3 the risk of PWD and piglets in PP group had ¼ of the risk of PWD from piglets. Feed conversion ratio differed between treatment groups (F 2,16 =2.85, P=0.0874) being significantly lower in PSP group compared to s (P<0.02 table 1). The addition of hydrolyzed brewery yeast in the feed did not influence daily weight gain in group housed healthy piglets not experiencing post-weaning diarrhoea.
The addition of hydrolyzed brewery yeast (Progut ) in piglet feed resulted in a dose dependent improvement in performance At a private Research Centre in France the efficacy of hydrolyzed brewery yeast (PG) was studied in comparison with negative and positive (Avilamycine 40 ppm) s. In weaning diets from 21 to 42 days 0,3%, 0,2% or 0,1% of PG was used followed by 0,1%, 0,1% or 0,07 % of PG in starter diets from 42 to 70 days, respectively. At the beginning of the trial 240 piglets were divided into treatments according to sex and initial weight. One treatment was replicated in six pens and in order to have an environmental challenge, pens and watering systems were neither cleaned nor disinfected after the previous group. During the whole trial period both the growth and feed conversion ratio in the group with 0,2%/0,1 % of PG in the feed and positive were significantly better than in the negative (table 2). Also piglets in group with 0,3/0,1% PG performed numerically better than negative but the differences weren't statistically significant. Based on the PG intake per day and performance results an optimal daily dose of hydrolyzed brewery yeast was calculated to be 0,9-1,0 g/piglet/day (figure 4). This corresponds to 0,3% of the product from 21 to 42 days and 0,1% from 42 to 70 days of age. Beneficial effects also with other animal species Scientifically proven functions of hydrolyzed brewery yeast product (Progut ) to prevent E.coli attachment, support natural immunity and stabilize commensal microbiota in gut are found to be beneficial also with many other animal species. The product has been tested and is commercially used also in feeds for layers, broilers, turkeys, calves and fish. More information at www.suomenrehu.com. Literature cited: Bauerfeind, R., Baljer, G. and Barth S. 2004 (personal communication) Berg, R. D. 1998. Probiotics, prebiotics or conbiotics? Trends Microbiol. 6:89 92 Breves, G. 2004. (personal communication) Bruininx, E. M. A. M., G. P. Binnendijk, C. M. C. van der Peet- Schwering, J. W. Schrama, L. A. den Hartog, H. Everts and A. C. Beynen. 2002. Effect of feed consumption on individual feed intake characteristics and performance of grouphoused weaned pigs. J. Anim. Sci. 80:1413 1418. Close, W.H. 2000. Producing pigs without antibiotic growth promoters. Advances in pork production, vol. 11. Jensen, K. et al. 2005 (submitted) Rautonen, N. and Apajalahti, J. 2002. The role of antibodies in gastrointestinal health of production animals. Feed Mix Vol.10, No. 1 2002. Turner, J. L., S. S. Dritz, and J. E. Minton. 2001. Alternatives to conventional antimicrobials in swine diets. Prof. Anim. Sci. 17:217 226. Vaahtovuo, J. et al. 2005 (submitted) Vuorenmaa, J. 2004. Regulation of gut immune responses and bacterial attachment by tailored feeds. Feed Mix Vol.12 No.6 2004.
Figure1. Unattached bacteria content in the supernatant after one-hour coincubation of F4-ETEC E.coli and different yeast products (mean from triple replicates, as % of relevant ). Justus-Liebig University Giessen 2004. 200 180 160 140 120 100 80 60 40 20 0 F4-ETEC Yeast B Yeast E S. Cerevisiae ref.strain E.coli % to E.coli F4 Figure 2. Average diarrhoea scores in piglet feeding trial at DIAS (Foulum) 2004 Average diarrhoea scores 6 5 4 3 2 1 0 PG +/+ /+ /- Control E.coli O149 challenged Average diarrhoea scores of PG fed piglets differed significantly from both with healthy and E.coli challenged piglets
Figure 3. Average diarrhoea days in piglet feeding trial at DIAS (Foulum) 2004 Diarrhoea days, index 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 Diarrhoea days, index E.coli E.coli E.coli PG +/+ /+ /- PG +/+ /+ /- Table 1. The effect of treatment groups on performance of group housed unchallenged piglets presented as means for the first 5 weeks after weaning. Daily weight gain, g per day per piglet Feed intake, g per day per piglet Water intake, L per day per piglet Feed conversion, kg feed per kg gain Progut for sow Progut for No Progut Statistical and piglets piglets only analysis 323 ± 45 327 ± 45 329 ± 44 NS 543 ± 40 520 ± 55 548 ± 43 NS 4,5 ± 1,0 3,8 ± 1,1 4,3 ± 1,6 NS 1,74 ± 0,17 a 1,64 ± 0,16 ab 1,93 ± 0,18 b P<0,1 a,b means with different subscripts within row differ significantly P< 0,02 Table 2. Performance results from 21-70 days. Private Research Centre in France 2005 Treatment Weight, kg Weight gain Feed intake g FCR kg/kg g/d A Negative 26,11 bc 410,5 bc 670 1,65 b B Positive 28,01 a 453,9 a 716 1,57 a F Progut 25,72 c 400,1 c 658 1,63 ab 0,1/0,07% Progut 27,90 a 447,6 a 697 1,56 a 0,2/0,1% Progut 0,3/0,1% 27,24 ab 432,5 ab 710 1,63 ab
a b c values with different superscripts within columns differ statistically (p<0.05) Figure 4. Optimal dose of hydrolyzed brewery yeast (Progut ) per piglet and day Weight gain 21-70 days 460 450 440 430 420 410 y = -207.11x 2 + 416.82x + 238.08 R 2 = 1 FCR 21-70 days 1.64 1.63 1.62 1.61 1.6 1.59 1.58 1.57 y = 0.5154x 2-0.93x + 1.9768 R 2 = 1 400 1.56 390 0.00 0.50 1.00 1.50 Total Progut intake 21-70 days (g/day) 1.55 0.00 0.50 1.00 1.50 Total Progut intake 21-70 days (g/day)