Effects of medium-chain fatty acids as alternatives to ZnO or antibiotics in nursery pig diets

In vitro and in vivo antiviral activity of monolaurin against Seneca Valley virus

Introduction

Surveillance of the Seneca Valley virus (SVV) shows a disproportionately higher incidence on Chinese pig farms. Currently, there are no vaccines or drugs to treat SVV infection effectively and effective treatment options are urgently needed.

Methods

In this study, we evaluated the antiviral activity of the following medium-chain fatty acids (MCFAs) or triglycerides (MCTs) against SVV: caprylic acid, caprylic monoglyceride, capric monoglyceride, and monolaurin.

Results

In vitro experiments showed that monolaurin inhibited viral replication by up to 80%, while in vivo studies showed that monolaurin reduced clinical manifestations, viral load, and organ damage in SVV-infected piglets. Monolaurin significantly reduced the release of inflammatory cytokines and promoted the release of interferon-γ, which enhanced the viral clearance activity of this type of MCFA.

Discussion

Therefore, monolaurin is a potentially effective candidate for the treatment of SVV infection in pigs.

Comparison of caproic acid and monolaurin with zinc oxide and benzoic acid; effect on growth performance of weaned pigs

Medium chain organic acids (MCOA) offer the potential to replace zinc oxide, without dependence on antibiotic use, and can replace or reduce the use of benzoic acid in pig production. A study was conducted to evaluate the effects of caproic acid (C6) and C12 monolaurin (C12M) on the growth performance of weaned pigs, in comparison with zinc oxide (ZnO) and benzoic acid (BA). Specifically, the trial examined whether MCOA, at a reduced inclusion level of BA, could maintain performance levels of pigs similar to those receiving a higher inclusion level of BA. In total, 240 pigs from weaning until 27 d post-weaning were used in a completely randomised block trial with six treatments and eight replicate pens per treatment. Treatments were: (1) control (CON), basal diet (BD); (2) BD+ZnO (ZnO); (3) BD+5,000 mg/kg BA (BA); (4) BD+2,500 mg/kg BA+2,000 mg/kg C12M+700 mg/kg C6 (BAlow/MCOA); (5) BD+2,000 mg/kg C12M+700 mg/kg C6 (MCOA); (6) BD+1000 mg/kg C12M+700 mg/kg C6 (MCOAlow). Feed and water were provided ad libitum. Pigs receiving BA or BA low/MCOA had improved feed conversion ration (FCR) during the period 0-14 days, compared with control pigs (1.02 vs 1.17, P<0.05; 1.06 vs 1.17; P=0.084, respectively). The FCR of pigs receiving BAlow/MCOA was similar to those receiving BA at the higher inclusion-level. Pigs showed good health throughout the study, as indicated by clinical and faecal scores. Replacement of ZnO was inconclusive and further studies with more challenging health conditions are required to conclude benefits.

Measures Matter-Determining the True Nutri-Physiological Value of Feed Ingredients for Swine

Many types of feed ingredients are used to provide energy and nutrients to meet the nutritional requirements of swine. However, the analytical methods and measures used to determine the true nutritional and physiological ("nutri-physiological") value of feed ingredients affect the accuracy of predicting and achieving desired animal responses. Some chemical characteristics of feed ingredients are detrimental to pig health and performance, while functional components in other ingredients provide beneficial health effects beyond their nutritional value when included in complete swine diets. Traditional analytical procedures and measures are useful for determining energy and nutrient digestibility of feed ingredients, but do not adequately assess their true physiological or biological value. Prediction equations, along with ex vivo and in vitro methods, provide some benefits for assessing the nutri-physiological value of feed ingredients compared with in vivo determinations, but they also have some limitations. Determining the digestion kinetics of the different chemical components of feed ingredients, understanding how circadian rhythms affect feeding behavior and the gastrointestinal microbiome of pigs, and accounting for the functional properties of many feed ingredients in diet formulation are the emerging innovations that will facilitate improvements in precision swine nutrition and environmental sustainability in global pork-production systems.