2005

Summary

Their addition generally lowers the pH and buffering capacity of the diet, increases gastrointestinal acidity, proteolysis and nutrient digestibility, promotes beneficial bacteria at the expense of pathogens and modulates numerous physiological processes after absorption. Four major benefits can be expected:

• improved health and resistance to disease;
• faster growth;
• increased efficiency of diet utilisation;
• better carcass quality.

Also, secondary effects may be achieved with supplemental SCFA, i.e., less volatilised ammonia (“acidic rains”) and pollutants (N and P). This paper outlines some physicochemical features and mode of action of SCFA and their salts, which are commonly available for pig producers. Also, some nutritional, bacteriological and physiological responses to graded doses and sources of SCFA during post-weaning, growing-finishing and reproductive cycles of pigs are examined.

Introduction

Prevention of disease transmission and enhancement of growth and feed efficiency are critical factors in modern pig production. For more than 50 years enteric disease suppression and growth promotion have been effectively achieved by the inclusion of various antibiotics or chemotherapeutics at subtherapeutic doses into diets. The estimated economic benefits in terms of improved growth rates ranged from 3.3 to 8.8% and feed efficiency from 2.5 to 7.0% (Viaene and Verbeke, 1999).

However, in recent years more scientific evidence was gathered on a relationship between the feed medication and pathogenic resistance in human therapy (Aarestrup, 2000). In consequence, all in-feed antibiotics and chemotherapeutics will be banned in the EU by 2006. In this context, a particular scientific interest is now paid to the antimicrobial potency of short chain fatty acids (SCFA) and their salts when applied individually or as a mix.

This paper outlines some essentials on the physicochemical properties and mode of action of supplemental SCFA and their salts, which in conjunction with endogenous SCFA from particular sections of the gut, can be addressed for suppressing pathogenic growth/colonization and improving digestion, absorption, mucosal immunity, and trophic effects on intestinal brush border (villi and crypts). Besides, the effects of graded doses and sources of SCFA during post-weaning, growing-finishing and reproductive cycles of pigs on performance are presented.

Physicochemical Properties and Mode of Action of SCFA

Natural feed resources (fresh, pre-fermented or ensiled ingredients of plant or animal origin and additives) contain more than 100 carboxylic acids and/or derivatives. Among supplemental SCFA and their salts for pigs, a particular practical interest is focused on those listed in Table 1.

Among other acidifiers officially approved in the EU are the following: Nasorbate, Ca-sorbate, K-sorbate, tartaric acid, Na-tartarate, K-tartarate, NaKtartarate, NH3-formate, Na-formate, NH3 -propionate, Na-propionate, K-acetate, Ca-acetate, Na-diacetate, Na-citrate, K-citrate, K-lactate, benzoic acid and Nabenzoate. These acidifiers can be administered individually or as a mix (to broaden a spectrum of antimicrobial potency) via feeds or drinking water.

The solid acidifiers are easier to handle, whereas the liquid forms may be volatile (up to 20%) during spraying, and their disadvantage could be the corrosiveness and unpleasant odour). This disadvantage can be eliminated by a coating technology for the encapsulation and sustained controlled release taste masking. Moreover, this technology allows also controlling their site of action, as well as the velocity of release and dissociation (Von Felde and Rudat, 1998; Gauthier, 2002).

Further Information

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Source: Paper presented during the 2005 Banff Pork Seminar Procedings