Effects of fermented liquid feeds and Lactobacillus subtilis and phytase on pig performance and environmental impact

Nguyen Nhut Xuan Dung1, Le Lan Anh², Luu Huu Manh³ and Brian Ogle⁴

1Department of Veterinary Medicine, Agricultural College, Cantho University

lhmanh@ctu.edu.vn

2Department of Agriculture, Vinh Long province

3Department of Veterinary Medicine, Agricultural College, Cantho University

4 Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences

Abstract

A study was conducted to observe the effects of feeding growing-finishing diets as dry feed (BS: basal diet), as fermented liquid feed (FLF), feed fermented with 4% molasses (FLF_4%M), and as diets supplemented with phytase (BS_PHY) and Lacobacillus (BS_LAC) on growth performance, nutrient digestibility, phosphorus excretion, Enterobacteria counts and Salmonella of pigs from growing to slaughter. Twenty five Pietrain x (Landrace x Yorkshire) pigs (30 ± 1.5 kg) were allocated according to a randomized complete block design to the 5 treatments with five replicates. Live weight gain, feed conversion ratio of pigs fed FLF and BS were slightly improved as compared to the BS diet. Digestibility of nutrients was not different among diets. Total phosphorus excretion was significantly reduced in FLF, BS_LAC and BS_PHY as compared to the BS diet.  Enterobacteria counts in faeces of the pigs in FLF and FLF_4%M were significantly lower than in those given BS and BS_LAC. Salmonella was totally absent in faeces of all pigs. It is concluded that fermented feed tended to improved the live weight gain and feed conversion ratio, significantly reduced the Enterobacteria counts and decreased phosphorus excretion in the pig faeces.

Key words: Enterobacteria counts, feed conversion, fermented liquid feed, live weight gain, phosphorus excretion, Salmonella

Introduction

Many studies showed that organic n acids, such as lactic acid produced from fermented liquid feed has improved the performance of pigs (Mikkelsen and Jensen 1997; Russell et al 1996); enhanced nutrient digestibility, reduced plasma urea nitrogen of pigs (Nguyen Nhut Xuan Dung et al 2005) and reduced pathogens, such as Enterobacteria (Nguyen Nhut Xuan Dung et al 2005) and Salmonella in pig faeces (Canibe and Jensen 2003).

Traditional diets for pigs in Vietnam are characterized by the use of high amounts rice bran, which is high in total phosphorus (1.6%, NRC 2000 and Nguyen Nhut Xuan Dung 2005), mainly in the form of phytic acid (up to 90%), which is less available to the pig. Cromwell et al (1993) found that some organic acids would solubilize phytate-P and a low pH is essential for phytase action (Siener et al 2001). Fermented liquid feed produces lactic acid that may improve phytate utilization because phytase will function better at a low pH.

Therefore, the hypothesis is that fermented feed may improve phosphorus utilization and is possible to reduce organic phosphorus, nitrogen excretion and pathogens into the environment.

The aims of the study were firstly to compare the effect of natural fermented feed with using Lactobacillus spp. and commercial phytase on growth performance and feed intake of pigs. Secondly, the nutrient digestibility, nitrogen retention, plasma urea nitrogen, phosphorus excretion and prevalence of Salmonella and Enterobacteria were measured to determine the effect of fermented feeds.   

Materials and methods

Animals

25 growing pigs at a live weight of approximately 30 kg were individually penned and given the experimental diets for a period of 90 days. All pigs were vaccinated against infectious diseases before starting the experiment.

Dietary treatments

• Treatment BS: basal diet (dry feed)
• Treatment FLF: basal diet (soaked for 24h)
• Treatment FLF_2%Mo: basal diet + 2% molasses (soaked for 24h)
• Treatment BS_PHY: basal diet + commercial phytase enzyme, 500 UI/kg (dry feed)
• Treatment BS_LAC: basal diet + Lactobacillus spp (soaked for 24h)

 Feed:water ratio was 1:3, and soaking at room temperature (25-27⁰C). The composition of the feed ingredient and diet formulation are presented in Table 1 and 2. Feed ingredients were purchased at the same time from a local feed company. Lactobacillus contained 2.10⁷-2.10⁸ CFU/kg with the commercial name Biolactyl (Bayer Company). The commercial phytase supplemented was Honophos phytase, consisting of innositol-hexaphosphate phosphohydrolase (5000UI/g) (China)

Management

The daily allowance was set close to ad libitum to allow the pigs to take enough feed and avoid feed wasted. The diets were given in four meals at 7:30, 10:00, 13:30 and 17:00h.  Refusals were recorded every meal to measure feed intake, which was calculated on a daily dry basis. Weight gains were recorded monthly. Water was freely available throughout the experiment. At the end of the growing phase, the faecal and urine samples of four days were taken and stored in a freezer at -18^oC and finally pooled, thus giving 50 faecal and urine samples.

Chemical analysis

Feed samples were analysed in duplicate for dry matter (DM), ash, ether extract (EE) and phosphorus according to the standard procedures of AOAC (1984).  For determination of crude protein (CP = N x 6.25) of faeces, fresh samples were analysed to avoid losing ammonia. Neutral detergent fiber (NDF) was analysed according to Robertson and Van Soest (1991), modified by Chai and Udén (1998). At the end of the trial, blood samples were taken via external jugular vein into test tubes containing heparin and placed in ice prior to centrifugation. Plasma was collected from blood and urea nitrogen (PUN) was analysed by an enzymatic method using urease to produce ammonia and CO₂, the ammonia produced combines with 2 – oxoglutarate and NADH in presence of GLDH to yield glutamate and NAD. Faecal samples were aseptically collected at the end of the study, directly from the rectum and placed into wide-mouthed sterile bottles. For isolation and identification of Enterobacteria counts one gram of feed sample was weighed, serially diluted, and 100 ml aliquots were plated in MacConkey agar (Merck 1.05465). Enterobacteria were counted after 24-h incubation (37°C). Salmonella were increased on Muller Kauffman medium following 24 h of incubation at 30^oC, and then plated on MacConkey agar (Merck 1.05465).  

Experimental design

The experimental diets were allocated according to a complete block design with 5 replicates and 1 pig per replicate, thus giving 25 pigs.

Statistical analysis

All data were analysed by analysis of variance using the General Linear Model of the Minitab (version 13) software (Ryan et al 2000). If the treatment effect was significant at P<0.05, differences between means were tested with the Tukey procedure of the Minitab software

The model used was:

 Y_ij= µ + α_i + β_j + ε_ij,                           

where:

Y_ij = dependent variable, µ = general mean, α_i = diet effect (i = 1, 2,. ., 5), β_j = block effect (j = 1,2…5), ε_ij = residual error

The significant differences were analysed using a Tukey test

Results and discussion

Growth performance and feed conversion

The effect of the different dietary treatments on growth performance and feed conversion ratio (FCR), dry matter and nutrient intake of growing and finishing pigs is presented in Table 3 and Table 4. During the growing and finishing phases, pig fed the treated feeds had the same growth performance (P=0.78 and 0.86) and feed conversion ratio (FCR; P=0.25 and 0.17) as those pigs fed the BS diet. For whole period, the live weight gains were not influenced by dietary treatment (P=0.73), but tended to improved as compared to the BS diet.

During the growing period dry matter intake was not significantly influenced by dietary treatment (P=0.62), but during the finishing phase the pigs fed BS_LAC had lower dry matter intake than for the other diets (P=0.04). However, this trend disappeared when calculated for overall DMI (P=0.26). Back fat thickness was not different among diets.

Canibe and Jensen (2003) reported that piglets fed NFLF were heavier than those fed FLF, while the gain/feed ratio of pigs fed FLF was improved as compared to dry feed. However, Lyber et al (2005) reported that growth performance of growers and finishers fed soaked feed was improved and FCR was reduced as compared to the dry feed. Nguyen Nhut Xuan Dung et al (2005 and 2007) reported that pigs feed a fermented broken rice diet had higher daily gain than those fed dry feed, and the growth rate of pigs fed FLF in the present study was slightly higher than for the other diets. These results are in agreement with a review of Jensen and Mikkelsen (1998), where it is stated that the growth rate of pigs fed fermented feed is less consistent. The diet BS_LAC did not affect gain and feed conversion as also shown by Pollmann et al (1980). Lactobacillus may have a function depending on dietary carbohydrate. Also Park et al (2001) demonstrated that Lactobacillus Acidophilus only improved feed efficiency of piglets.

Digestibility and nitrogen retention

The digestibility of dry matter (DMD), organic matter (OMD), crude protein (CPD), ether extract (EED), NDFD and nitrogen retention are reported in Table 5.  The DMD, OMD, CPD, EED, NDFD and nitrogen retention tended to be improved in the diets  FLF, FLF_2%Mo, BS_PHY and BS_LAC, although they were not significantly different (P>0.05).  Similarity, PUN was similar among diets (P=0.78).  According to Hale and Newton (1979) the nutrient digestibility and PUN (Pollmann et al 1980) of pigs fed diets supplemented with Lactobacillus was not different from those on the basal diet. Nguyen Thi Thu Hong and Lindberg (2007) reported that growing pigs fed fermented feed had higher crude protein digestibility than that of raw or cooked feeds. Winsen et al (2001) explained that the fermented feed enhanced the digestibility of nutrients due to a reduction of substrates for microbial growth. 

Phosphorus excretion

The effect of fermented feed on phosphorus excretion is shown in Table 6. The data indicate that the diets FLF, BS_PHY and BS_LAC decreased P excretion in faeces (P=0.06) and total P excretion/P intake was significantly lower than for the BS diet (P<0.01). The utilization of organic phosphorus/P intake was increased in the treated feeds (P=0.05). This criterion is very important for evaluating the potential of fermented feed in reducing of P excretion to the environment.

Fredlund et al 1997; Skoglund et al 1997; Larsen et al 1999 and Lyberg et al 2006, reported that fermented feed can improve intrinsic phytase activity, and thus reduce P excretion. Lui et al (1997) also found that fermented feed increased phytase efficacy with increasing P absorbed. Fermented feed and diets supplemented with phytase and Lactobacillus increased the efficacy of using P. The positive effect of soaking feed on P utilisation was reported by Carlson and Poulsen (2003) and Lyberg et al (2005).

With the exception of FLF_2%Mo the aim of using molasses in this diet was to get rapid fermentation, but a quick fermentation resulted in highly acidic conditions and according to Carlson and Poulsen (2003) intrinsic phytase was reduced over time with pH below 5. This could explain the higher P excretion in FLF_2%Mo as compared to the other diets.

Enterobaceria counts and Salmonella excretion

The effect of fermented feed on Enterobacteria counts and Salmonella excretion is shown in Table 7. Enterobacteria counts were reduced in the treated feeds (P<0.01), particularly in the two fermented diets FLF (2.31 cfu/g x10⁶) and FLF_2%Mo (2.10 cfu/g x 10⁶) compared with BS (13.06 cfu/g x 10⁶), with the exception of BS_LAC. This result was silmiar to the report of Pollmann et al (1980), who found that supplementation of Lactobacillus to pig diets did not suppress E. coli. 

A reduction of Enterobacteria counts in the faeces of pigs fed fermented liquid feed has been shown by van Winsen et al (2001), who found that there is a positive correlation between pH and Enterobacteria counts. Nout et al (1989) stated that Coliforms and Salmonella were inhibited in the low pH conditions of fermented feed (below 4.5) compared with dry feed (Russell et al 1996; Jensen and Mikkelsen 1998).

Salmonella was totally absent in the faeces, although there were  not enough data to say that fermented feed influences this bacteria, as normally Salmonella is not detected in the feed, and therefore were not isolated in the faeces in this study. van der Wolf et al 2001 reported that fermented feed reduces Salmonella in pigs, and Dahl (1997, cited by Scholten,1999) demonstrated that Salmonella numbers are lower in pigs fed FLF. 

Conclusions

• Fermented liquid feed and the diets supplemented with Lactobacillus and phytase tended to improve gain and feed efficiency of pigs, and reduced Enterobacteria and phosphorus excretion into the environment.

• These improvements may be due to a low pH condition, which inhibits the growth of Enterobacteria and stimulates phytase activity, thus improving phosphorus absorption.

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