Bacterial Inoculant Effects on Corn Silage Fermentation and Nutrient Composition (Report‪)‬

INTRODUCTION The main aim of silage making is to conserve the plants with minimal loss of nutritive value by fermentation of soluble carbohydrates in an anaerobic environment into organic acids, preferably lactic acid, which reduce pH (Saarisalo et al., 2007). The fermentation quality of silages has a major effect on feed intake, nutrient utilization and milk production of ruminants (Huhtanen et al., 2002, 2003). Fresh whole corn (Zea mays, L.) dry matter (DM) which generally contains 30-40% grains is rich in linoleic acid (LA, [C.sub.18:2], 55-62%) and oleic acid ([C.sub.18:1], 24-32%) and poor in [alpha]-linolenic acid (ALA, [C.sub.18:3], 2%; Chilliard et al., 2007). Concentrations of ALA vary with plant and environmental factors such as stage of maturity, genetic differences, as well as season and light intensity (Elgersma et al., 2006). When forages are conserved as silage, they maintain the same concentration of long chain-FA as when harvested fresh (Chilliard et al., 2001). Lactic acid bacteria (LAB) are often used as silage additives to enhance lactic acid fermentation, hence to better preserve the ensiled material. Bacterial inoculants have advantages over chemical additives because they are easy to use, safe, do not pollute the environment and are regarded as natural products. Most commercially available inoculants contain homofermentative LABs, which improve the silage fermentation. Among the homofermentative LAB most frequently used are Lactobacillus plantarum, L. acidophilus, Enterococcus faecium and Pediococcus acidilactici. Numerous papers have reported the ensiling of corn without inoculants (Abdehadia et al., 2005; Kozakai et al., 2007), with the inoculants Lactobacillus plantarum (Filya, 2003), Lactobacillus buchneri, and Propionibacterium acidipropionici (Filya and Sucu, 2007), commercial inoculants containing lactobacilli, enterococci, pediococci (Weinberg et al., 2004) and with mixtures of inoculants, such as L. plantarum+L. buchneri (Filya, 2003), L. plantarum+Enterococcus faecium; and L. plantarum+ Pediococcus acidilactici (Sucu and Filya, 2006; Koc et al., 2008). Some in vitro experiments showed that certain microorganisms e.g., lactobacilli, lactococci, propionibacteriae, bifidobacteriae and enterococci are able to form conjugated linoleic acid (CLA, cis 9, trans 11 [C.sub.18:2]) from linoleic acid in special growth medium (Coakley et al., 2003; Sieber et al., 2004). However, Bessa et al. (2000) revealed the possibility of an alternative pathway in the production of CLA from linolenic acid ([C.sub.18:3]) due to extreme microbial diversity in the reticulo-rumen. Also, our screening of microorganisms showed that some lactobacilli and enterococci isolated from rumen fluid and silages were able to convert linoleic acid (LA) to CLA in special growth medium in vitro (Marcinakova, 2006). The objective of this study was to evaluate the survival and effect of three new probiotic inoculants (isolates of our Institute and L. plantarum CCM 4000 which was kindly supplied by Dr. Nemcova, University of Veterinary Medicine, Kosice, Slovakia) on corn silage fermentation and chemical composition (including mainly polyunsaturated fatty acids, PUFA).