Abstract: The aim of this study was to evaluate the effects of ensiling corn harvested at the milk stage by addition of various amount of Molasses (M), Urea (U) and Urea + Molasses (UxM) on quality, in vitro Organic Matter Digestibility (IVOMD) and Metabolic Energy (ME) contents. Five silage samples from 16 treatment groups were prepared in 1 l jars and incubated for 70 days. The ME values and IVOMD with lactic acid levels of 1% U added silages were higher compared to other silages. It has been concluded that either unsupplemented or 1% U added ensiling will be a suitable ensiling technique to corn.

INTRODUCTION

In silo fodder production, mostly corn and sorghum type and their half-breeds are cultivated (Iptas et al., 1997; Kiliç, 1986). Besides corn silage having a higher energy level compared to sorghum silage (Grant and Stock, 1995), it is reported to be in a better condition in terms of digestibility and fodder value (Grant and Stock, 1995; Bakici and Demirel, 2004). Corn within silo fodders is considered an ideal silo fodder for its productivity level and having high levels of easily soluble carbohydrate contents (Bilgen et al., 1997).

Urea and molasses are widely used to increase nutrient content, digestibility and consequently feed value of various silages, particularly corn (Kiliç, 1986; Undersander et al., 1990; Filya, 2003).

Aim of this study was to evaluate the effects of ensiling corn harvested at the milk stage by addition of various amount of urea, molasses, ureaxmolasses on quality in vitro organic matter digestibility and metabolic energy value.

MATERIALS AND METHODS

In the corn harvested at the milk stage Control (C) and according to weight structure, by adding 0.5, 1 and 1.5% Urea (U); 5, 10 and 15% Molasses (M) and 0.5 Ux5% M, 1% Ux5% M, 1.5% Ux5% M, 0.5% Ux10% M, 1% Ux10%M, 1.5% Ux10% M, 0.5% Ux15% M, 1% Ux15% M, 1.5% Ux15% M, UreaxMolasses (UxM), 16 different silage samples were prepared. From each sample with 5 repetition totally 80 silage sample were incubated for 70 days in 1 L glassware jars.

Proceeding the fermentation, by extracting liquid out of silage samples (Hart and Horn, 1987), silage pH’s and organic acid analysis were made. Acetic, propionic and butyric acid analysis were made in Gas Chromatography device (Dawson and Mayne, 1995), lactic acid analysis in Spectrophotometer by using lactate kit (RANDOX).

In the opened silages, flieg points and quality classifications were determined according to Kiliç (1986). CP, DM and CF analysis of the silages were made according to Weende Analysis system (Bulgurlu and Ergül, 1978). Van Soest et al. (1991) method were used to analysis ADF and NDF (Table 1).

Tilley and Terry’s (1963) procedure were used to determine in vitro Organic Matter Digestibility (IVOMD) and Metabolic Energy (ME) values of silage samples. Ruminal ingesta from an alfalfa fed ruminally fistulated ram was hand-collected and strained through four layers of cheesecloth to provide the inoculate for IVOMD determination.

Statistical analysis of the data’s found were made according to factorial trying pattern designed in random partitions (Düzgünes et al., 1987) and mathematical model below was used.

Y_ujk = μ + a_i + b_j + (ab)_ij + e _ujk

Table 1:	Chemical compositions (DM%), flieg points and quality classification of different additional silages
1Fresh material; C: Control; U: Urea, M: Molasses

Where:

SAS (1998) was used for data analysis, which is least squares mean, analysis of variance and Duncan multiple range (Düzgünes et al., 1987) test used for pair wise comparison of mean of silage groups.

RESULTS AND DISCUSSION

The dry matter contents of the corn harvested at the milk stage was found to be 22.92%. Addition of urea, molasses, ureax molasses did not effect the silage’s food stuff ingredients and flieg points and best quality of silages were produced (Table 1). High correlation was found between silo fodder and quality class (Alcicek and Özkan, 1997).

The effects of urea, molasses and ureaxmolasses on mean pH, lactic, propionic, butyric acid concentrations and ME value of silages were not significant, but on acetic acid and IVOMD were significant (p<0.01, p<0.05), respectively. When doses of urea, molasses and ureaxmolasses were considered the doses affected pH, lactic, acetic acid, IVOMD and ME values (p<0.01) and butyric acid concentrations (p<0.05).

Silage pH values found range between 3.61 and 4.02 (Table 2). As different urea doses had no effect on the pH of the control silage, 10 and 15% molasses addition decreased the pH (p<0.01). The effects of ureaxmolasses doses displayed no regular change. It was reported that silage pH level changed depending on dry matter content of silage material. For the best silage the pH value ranged 3.5-4.2 and organic acid level, especially lactic acid levels associated with silage quality (Kiliç, 1986; Alçiçek and Ozkan, 1997; Meeske et al., 2000).

Although, the lowest lactic acid concentration (1.35%) was observed at 1.5% U silage groups and also it similar to level observed from control silage (2.25%), it was found out to be lower than the 1% U silage group, which highest lactic acid concentration (2.98%) was observed (p<0.01).

The effects of urea and molasses on mean acetic acid concentrations were significant; but ureaxmolasses mixture groups increased acetic acid concentration from 2.32-4.66% (p<0.05). Increasing of urea and molasses doses did not change the acetic acid concentration. Urea and molasses joining silages together generally increased the acetic acid concentration. The highest acetic acid concentration was determined in 0.5 Ux15% M silage (6.30%). As the highest butyric acid concentration was (1.03%) observed from 1% Ux15% M silage, the lowest concentration (0.30%) was determined in 0.5% U silage (p<0.01). The increasing doses of urea and molasses had no effect on butyric acid concentration.

pH level and organic acid concentrations of silages are the most important characters of silage fermentation quality (Kiliç, 1986; Filya, 2000). While, urea or ureaxmolasses addition increase silage pH, acetic and butyric acid concentration levels, it also reported to have no effect on lactic and propionic acid (Demirel et al., 2003). In another study, carried out by Demirel et al. (2004), it was reported that urea or urea plus molasses applications increased the concentrations of acetic and lactic acid, but did not affect the butyric acid concentration. Çerçi et al. (2001) also mentioned that with 0.5% urea addition to silages, the concentration of lactic acid increased, but there was no negative effect of it on fermentation. Increasing protein levels of silages did not affect silage fermentation quality in different studies (Hart, 1990).

Table 2:	Fermentation characteristics in vitro organic matter digestibility (DM%) and metabolic energy values (kcal kg-1 DM) of different corn silages
*p<0.05, **p<0.01; Values with different letters in the same column differ significantly A, B (p<0.05); a-e (p<0.01)

Generally, the effects of U, M and UxM on mean IVOMD and ME values of silages were not affected, when doses of U, M and UxM were considered, the differences among doses were statistically significant (p<0.05). The highest IVOMD and ME value was determined in 1% U additional silage group. This situation could be explained by the effect of urea, which was used in silage fermentation on the structural carbohydrates in cell wall (ADF and NDF); while urea increased the degradability of DM, OM, ADF and NDF, it decreased the level of NDF and ADF in cell wall. Besides, Bolsen et al. (1996) have reported that urea and ammoniac increases the digestibilities of DM, OM and cell wall components of silages.

IVOMD of two different corn hybrid silages ranged between 56.7 and 72.4%, ME values between 8.73 and 10.20 MJ DM^-1 (Meeske et al., 2000; Garcia et al., 2000) and in another study, carried out by Meeske et al. (2002), IVOMD of the corn silage was found to be 65.4 and 70.5% in turn in order. Faria and Huber (1984) reported that increasing levels of urea on corn silage increases CP level and proportionally increases IVOMD from 57.84-62.80%.

CONCLUSION

As a result, satisfied silages were obtained in terms of fermentation properties. However, it should be concluded that unsupplemental or 1% U could be preferred when silage fermentation quality, organic matter digestibility and ME values are taken into consideration.