Probiotics for horses:pH colon

Trial#57: Variation of large colon pH in horses after administration of lactic.

Introduction

The use of probiotic in horse gained popularity in the past few years as a feed ingredient to control nutritional disorders or intestinal pathogens (Boldt et al. 1997; Parraga et al. 1997; Steffans 1997). Other researches have indicated a positive effect of probiotic administration in growth and blood metabolic parameters in foals (Abd et al. 1998; Stefanon et al. 1999) or in exercising horses (Art et al. 1994).
In particular, the positive action of lactic probiotic should be due to the modulation of the large intestinal activity of microflora, which would be reflected in higher efficiency of fibre degradation and mineral absorption (Glade 1993; Pagan 1993) The increase fibre fermentation would determine higher volatile fatty acids concentrations in the intestine and, in the case of probiotics containing lactic producing micro-organisms (Turval with Kluiveromyces f. B0399), higher lactic acid. The overall effect would be a control of pathogen bacteria strains, through a decrease of large intestinal pH and a substrate competition.
In various field trials there was a beneficial effect on severe cases of colics and aerophagies (Delogu-Cherchi 1996, Huff 1997, Ferrari 1996). If the positive effect on general health status and nutritional efficiency has been demonstrated, no convincing indications on the modifications of intestinal pH are at the moment yet available.
The effect of lactic probiotic “TURVAL 6 horse daily” on the pH value at the large colon level was reported by Smally (1997) in 3 mares by colon laparatomy (Smally 1997). The aim of this paper is to identify a non invasive method to assess variation of intestinal pH and to verify if the administration of TURVAL 6 could interfere on this value.

Material and Methods

The probiotic used in the trial is “TURVAL 6 Daily Horse”, composed of the following ingredients: dried distillers, Turval Bâ (tipified lactic yeast Kluiveromyces f.B0399, whey, hydrolyzed proteins, natural fermentation metabolites), wheat bran, brewer's grain.
The probiotic is produced by TURVAL Laboratories s.r.l. Udine – Italy EU.

Experiment 1. The trial was conducted in a local slaughterhouse. 20 adult horses: 7 females and 13 males of different breeds and similar medium size, were slaughtered and the viscera immediately taken. Caecum, Colon and small Colon were dissected for pH determination, which was conducted by immersing the electrode in the gut content. In the rectum, the pH was measured directly in the faeces.

Experiment 2. For this trial 5 adult Quarter horses, 3 females and 2 males, were used. Animals received a daily ration consisted of 8 kg grass hay (12.0% moisture, 11.3% CP) and 3.5 kg of a commercial concentrate (13.0% moisture,14.0% CP, 4.0% EE, 7.0% CF, 6.2% ash). Hay was offered 3 times a day and concentrate twice a day (about 7.0 a.m. and 16.0 p.m.). Faecal pH was measured in grab samples collected at day 0, +2, +3 and +4 from the beginning of the experiment. 50 g of faecal sample were added with 100 ml of distilled water and thoroughly mixed before pH determination. Starting from 1.40 g of probiotic was administered at the morning meal together with concentrate.

Data were subjected to statistical analysis with the general linear model and the regression analysis of the release 7.5 of the SPSS package (1995).

Results and Discussion

The aim of the experiment 1 was to evaluate the possibility to use faecal pH has an indicator of the pH in the large intestine. Alternatively, a direct determination of pH in the large intestine tract would require the use of invasive technique, such as intestinal cannula, or the sacrifice of the horse, both during and at the end of an experiment. The results reported in table 1 and figure 2 indicate a significant relationship between pH measurements in the faeces contained in the rectum and the intestinal content sampled at the caecum and at colon and small colon). The coefficient of determination was higher than 0.85 and the highest value was observed for the colon trasversus (0.896), whilst the lowest was obtained for the caecum (0.864). Moreover, for the both the samples collected at the colon, the constant was not significant different from 0 and the slope was very close and not significant different from 1. The pH measured at the caecum level was on average 0.413 (constant significant for P<0.05) unit higher than that determined in the faeces, but the slope of the regression still approximate the unity (P > 0.05).
In the experiment 2, the suggested daily dose of TURVAL 6 was fed to 5 Quarter Horses, in order to assess if the probiotic could act as a modulator of large intestinal fermentation. According to the manufacturing indication, the probiotic should stimulate the lactic acid microflora, increasing its concentration in the large intestine content. The regression equation obtained for the colon trasversus (table 1) was used to covert the pH measured in the faeces in expected values at the colon level. The results clearly indicate the sharp decrease of the pH colon trasversus (figure 5), which was already significant after 3 days.

Conclusion

The results of the experiment 1 indicates that faecal pH can be used to monitor the acidity condition of the large intestine. On the basis of this data it can be concluded that the significant decrease of faecal pH observed after probiotic ingestion reflects a change of the fermentation in the large intestine, colon included.
Moreover, the action of probiotic is fast and can be observed after just a couple of days.
However, these results can be viewed only as preliminary, and further experiments are required in order to expand observations to other feeding regimes and to assess the dose response curve and the persistency of the probiotic effect in a longer period of time.