Abstract: Five types of silage were made from Vegetable and Fruit Market Wastes (VFMW) to evaluate silage quality. The different types of silage were, VFMW (S1), VFMW+5% ortho-p-acid (S2), VFMW+5% formic acid (S3), VFMW+5% 1: 1 ortho-p-acid: formic acid (S4) and VFMW+5% sodium acetate (S5). After 21, 42 and 64 days the siloes were opend and the silages characteristics were examined. Supplementation of chemical agents to VFMW silage (S2, S3, S4 and S5) were significantly increased dry matter, organic matter, crude protein, ether extract and nitrogen free extract contents, while crude fiber content was significantly decreased (p<0.01) with treated silage compared with control (S1). In vitro dry matter (p<0.01) and organic matter (p<0.05) disappearances were significantly higher with formic acid+ortho-p-acid and sodium acetate (S4 and S5) treated silage followed by ortho-p-acid and formic acid (S2 and S3) and then control (S1). Silage pH value was decreased (p<0.01) with adding ortho-p-acid and sodium acetate to silage, while, silage butyric acid concentration was increased (p<0.01) with ortho-p-acid and decreased (p<0.01) with the combination of acids adding to silage compared with control. On the other hand, ammonia-N, lactic acid were not among treatments. Silage pH, ammonia-N, butyric acid and lactic acid concentrations were increased (p<0.01) with time of ensiling. Nine castrated goat's male average (26.2 kg and 4 years age) were divided into three groups using 3x3 Latin square design with 30 day periods to study the effect of treatments on rumen activity and nutrient digetibilities. DM, OM, CP, CF, EE and NFE digestibilities were increased (p<0.05) with treated groups compared with control. Rumen total nitrogen, true protein nitrogen and non protein nitrogen contents were increased (p<0.05) while, ammonia-N content was decreased (p<0.05) with treated groups compared with control. Fifteen lactating Zaraibi goats after seven days of parturition were ranked to three groups using 3x3 Latin square design with 30 day periods to study the effect of treatments on milk yield and composition. Animals were fed on Concentrate Feed Mixture (CFM): VFMW silage (S1), CFM: VFMW treated with 5% formic acid (S2) and CFM: VFMW treated with 5% sodium acetate (S3). Milk yield and 4% FCM were increased (p<0.01) with treated silage. Yields of milk contents were higher (p<0.05) in treated group compared with control. However in milk, total protein, fat, lactose and solids not fat contents were not differed significantly among treatments. Chemical treated silage improved (p<0.05) feed efficiency (milk Yield/Dry Matter Intake (DMI) and 4% FCM/DMI) of VFMW silage. Blood serum glucose increased (p<0.05) while, urea and total lipids decreased (p<0.05) with treated groups compared with control.
INTRODUCTION
In Egypt, the yield of vegetable and fruit were estimated about 14.1 and 7.1 million tons per year, respectively (General Statistics Year Book, 1998) of which about 3.95 million tons from both of them are wasted yearly during marketing. Many agricultural an agro-industrial by-products have considerable potential as animal feed. Many of theses by-products currently go either unused or largely wasted. Consequently these by-products often become pollutants (Kayouli and Lee, 1998). The problem usually encountered with agro by-product is seasonality of supply, which is often accentuated by their high moisture content. Dehydration increases cost about 250-300 L of fuel and 200 kwh of electricity and required to produce one ton of dry product (88-90% DM). Research has shown that the ensiling of by-product is the most suitable method of conservation for long period (Bouque and Fiems, 1988; Kayouli et al., 1993; Kayouli and Lee, 1998). Successful silage fermentation depends on achieving both anaerobic conditions and a low pH. The low pH, which is usually accomplished through the fermentation of sugars in the ensiled materials to lactic acid by lactic acid bacteria or by addition of some organic and inorganic acids as formic, propionic and sulphoric acids (O'Kiely, 1996; Kung and Ranjit, 2001; Adesogan and Salawu, 2004) or organic salts propionate and formate (Adesogan et al., 2003). Application rates of formic acid (2-5 L t-1 grass) resulted in substantial increase in silage intake and improved animal performance even when the untreated silages were well preserved (Henderson et al., 1989, 1990; Parker and Crawshaw, 1982). Many studies were used formic acid only or with chemical additives to improved silage quality (O'Kiely and Moloney, 1994; O'Kiely, 1993, 1996; Adesogan and Salawu, 2004) and their effect on rumen fermentation and digestibility (Moloney and O'Kiely, 1994). However, low published studies on this subject have focused on dairy animals performance.
The present research is an attempt to supplement of some chemical agents to ensiled VFMW and their effect on silage quality, nutrient digestibilities, rumen parameters and milk yield and composition of lactating goats.
MATERIALS AND METHODS
A mixture of orange waste, potato waste and pea-pods collected from market wastes, were ensiled without (S1) or with the following chemical supplements: 5% ortho-p-acid (S2), 5% formic acid (S3), 5% ortho-p-acid: formic acid (1:1) (S4) or 5% sodium acetate (S5) in five silos (750 kg capacity). After 21, 42 and 64 days, the silos were opened. Color and odder were estimated and samples were taken for chemical analysis according to the official methods of the AOAC (1995). Other samples were pressed and the juice was collected for the estimation of pH (digital pH meter), ammonia nitrogen (kjeldahl), butyric acid and lactic acid (Hawk et al., 1954). Then in vitro dry matter and organic matter disappearances were done on samples of different treatments according to Tilley and Terry (1963), modified by Norris (1976).
Digestibility Trial
The coefficients of digestibility, nutritive value and rumen activity were
determined for selected silage using castrated male goats. Nine animals (average
26.2 kg and 4 years age) were divided into three groups (three animals each)
using 3x3 Latin square design with 30 day periods. Animals were fed on Concentrated
Feed Mixture (CFM): VFMW silage (S1) (50:50), CFM: VFMW treated with
5% formic acid (S2) (50:50) and CFM: VFMW treated with 5% sodium
acetate (S3) (50:50). The CFM consisting of 35% yellow corn, 25%
wheat bran, 22% decorticated cotton seed cake, 15% rice bran, 1.5% ground limestone
and 1.5% common salt. The chemical composition of different silage type are
showed in Table 1. The offered feeds were assessed to cover
the requirements for each animal (ARC, 1965). The CFM was offered for each animal
individually once daily at 8.00 am while silage was offered at 10.00 am. Dry
matter intake was measured during the last refusals of the previous day. Water
was available at all time.
Fifteen lactating Zaraibi goats (average 29.4 kg and 4 years age) were divided into three groups (five animals each) using 3x3 Latin square design with 30 day periods to study the effect of different types of silage on milk yield and composition. The same rations and managements of digestibility trial were used on lactation trial.
Sampling and Analysis of Rumen Liquor
At the last day of each period of digestibility trial, rumen liquor samples
were collected from each animal at 4 h. post morning feeding by a stomach tube.
The samples were strained through two layers of cheese cloth and then stored
in glass bottles (10 mL) with 3 drops of toluene and a thin layer of paraffin
oil just to cover the surface to stop microbial activity and to prevent volatilization
and stored at -18°C till they were analyzed. Ruminal pH was determined using
a digital pH-meter, Total Nitrogen (TN), Non-Protein-Nitrogen (NPN) and ammonia-N
were determined according to AOAC (1995). True Protein Nitrogen (TPN) was calculated
by difference. Total Volatile Fatty Acids (TVFA’s) were determined by steam
distillation as described by Warner (1964).
Sampling and Analysis of Milk
At the last 3 days of each period, Zaraibi goats were hand milked (twice/day),
milk yield was recorded and pH of milk was determined. Milk samples were also,
analyzed for fat, Total Solids (TS), Total Protein (TP), ash (Ling, 1963) and
lactose (Barrnett and Abd El-Tawab, 1957). Solids-Not-Fat (SNF) was calculated
by difference.
Sampling and Analysis of Blood Serum
Blood samples were collected from the jugular vein of each animal at the
last day of each period (4 h post morning feeding). The collected blood samples
were centrifuged at 4000 rpm/20 min to separate the serum. The obtained serum
was stored at -18°C till it was analyzed. Serum total protein was determined
as described by Armstrong and Carr (1964), while, albumin (Doumas et al.,
1971), urea (Patton and Crouch, 1977), glucose (Siest et al., 1981),
total lipids (Postma and Stroes 1968), serum Glutamic-Oxaloacetate-Transaminase
(GOT) and Glutamic-Pyruvate-Transaminase (GPT) (Reitman and Frankel, 1957).
Globulin and albumin/globulin ratio were calculated.
Statistical Analysis
Data obtained from this study were statistically analyzed according to procedures
outlined by Snedecor and Cochran (1982). These procedures were:
| • | Latin square design for nutrients digestibility, yield and composition of milk and blood parameters using the general linear model procedure: |
Yijk = μ+Ri+Cj+Tk+eijk |
Where Yijk is the parameter under analysis of the ijk goat, μ is the overall mean, Ri is the effect due to the lactation period on the parameter under analysis, Cj is the effect due to the animals on the parameter under analysis, Tk is the effect due to treatment on the parameter under analysis, eijk is the experimental error for ijk on the observation,
| • | Splite plot design for rumen liquid parameter: |
Yijk = μ+Ri+Tj+(RT)ij+Bkt+(TB)jk+Eijk |
Where, Ri: Replicate, Tj: Treatment, (RT)ij: Interaction, Bkt: sampling time, (TB)jk: interaction (TB) and Eijk: Experimental error.
The Duncan's multiple range test was used to test the significance between means (Duncan, 1955).
RESULTS AND DISCUSSION
Silage Quality
The present results showed that supplementation of chemical agents to VFMW
silage (S2, S3, S4 and S5) were
significantly increased dry matter, organic matter, crude protein, ether extract
and nitrogen free extract contents, while crude fiber content was significantly
decreased (p<0.01) with treated silage compared with control (S1)
(Table 1). Ortho-p-acid increased crude protein content of
silage by binding proteins and protecting protein from proteolysis. The effect
of added formic acid in this study was applied at an adequate rate. It is capable
of promoting a lactic acid fermentation under conditions where a clostridial
fermentation would otherwise have occurred (Wilson and Wilkins, 1973). These
results were due to the reduction of dry matter losses of treated silage (Adesogan
et al., 2003). Similar results were obtained by Moloney and O'Kiely (1994).
According sampling time of silage, dry matter, organic matter, nitrogen free
extract and crude protein contents were significantly increased (p<0.01).
However, crude fiber and ether extract contents were decreased (p<0.01) with
time.
In vitro dry matter (p<0.01) and organic matter (p<0.05) disappearances
were significantly higher with formic acid + ortho-p-acid and sodium acetate
(S4 and S5) treated silage followed by ortho-p-acid and
formic acid (S2 and S3) and then control (S1)
(Table 2). IVDMD and IVOMD were slightly increased (p>0.05)
with time while there were no difference effect between 42 and 64 days of silo.
| Table 1: | Chemical composition of experimental silage at different ensiled stages |
| A,B,CMeans with different superscripts are significant (p<0.01) difference; a,b,cMeans with different superscripts are significant (p<0.05) difference | |
| Table 2: | Silage quality and dry matter and organic matter disappearances of untreated and treated vegetable and fruit market wastes silage at different ensiled times (% DM) |
| A,B,CMeans with different superscripts are significant (p<0.01) difference; a,b,cMeans with different superscripts are significant (p<0.05) difference | |
Adesgan et al. (2003) found that in vitro dry matter and organic matter digestibility values were not affected by addition of ammonium formate, propionate, ethyle benzoate and benzoate to crimped wheat grains.
The pH values of juice pressed from the silages were within the desirable range of pH (3.9 to 4.8) of good quality silage. S2 and S5 silage were significantly decreased pH values compared with control (Table 2). Our results were slightly higher than results of Adesogan et al. (2003) and Adesogan and Salawu (2004) who reported that pH value was significantly decreased in the juice of pea silage added with formic acid. Ammonia-N and lactic acid concentrations were not affected by treatments. Adesogan and Salawu (2004) found that ammonia-N concentration decreased with Magnus pea treated by formic acid. Butyric acid concentration was significantly higher (p<0.01) with ortho-p-acid and lower (p<0.01) with formic and ortho-p-acids compared with control. Formic acid treated silage recorded the lowest value while, ortho-p-acid treated silage recorded the highest value of butyric acid. Adesogan and Salawu (2004) reported that concentration of lactic acid and butyric acids were lower in formic acid treated silage than in control. pH value, ammonia-N, lactic acid and butyric acid concentrations were significantly increased (p<0.01) with ensiling time (Table 2).
Digestibility Trial
Formic acid (S2) and sodium acetate (S3) increased (p<0.05)
the intake of silage by goats fed on treated silage compared with control. Formic
acid (S2) and sodium acetate (S3) had higher (p<0.05)
digestion coefficients of DM, OM, CP, CF, EE and NFE compared with control silage.
The silage additives were also improved (p<0.05) nutritive value of silage
than control (Table 3 and 4). These increases
of digestibility coefficients may be due to the increases of OM, EE and NFE
contents and the decrease of CF content of treated silage (Table
1), which improved animals utilization of treated silage compared with control
silage. Similar results were obtained by Moloney and O'Kiely (1994).
Rumen Parameters
Table 5 results showed that sodium acetate slightly decreased
rumen pH than other treatments. All pH values were above 6.0 which indicated
a better digestion of cellulolytic materials (Mertens, 1978). On the other hand,
TVFA's concentration were higher (p>0.05) with treated silage than control.
The lower TVFA's concentration for the control silage reflects the lower intake
of digestible dry matter from this silage compared with treated silages (Table
4). Similar results were obtained by Moloney and O'Kiely (1994) with formic
acid or organic acid complex treated grass silage. Ammonia-N concentration decreased
(p<0.05) while, total nitrogen, true protein nitrogen and non protein nitrogen
increased (p<0.05) with animals fed on treated silages compared to control
group. These finding explain the improvement occurred in the rumen lead to higher
microbial protein synthesis of animals fed treated silages. El-Sayed (2002)
and Abo El-Nor and Kholif (2005) obtained similar results with goats fed on
sodium acetate supplemented rations.
Milk Yield and Composition
Data presented in Table 6 showed that dry matter intake
was slightly increased (p<0.05) with animals fed on treated silage compared
with control. Milk yield and 4% FCM were significantly higher (p<0.01) in
animals fed on treated silages compared with control.
| Table 3: | Chemical analysis of feedstuff ingredients used in formulation rations (on DM basis) |
| CFM: concentrate feed mixture; S1: Untreated silage; S2: Treated silage with formic acid; S3: Treated silage with sodium acetate | |
| Table 4: | Average daily dry matter intake, nutrient digestibility coefficients and nutritive value of goats fed on experimental rations |
| S1: Untreated silage; S2: Treated silage with formic acid; S3: Treated silage with sodium acetate; a,b,cMeans with different superscripts are significant (p<0.05) difference | |
| Table 5: | Average rumen liquor parameters of goats fed on experimental rations |
| a,b,cMeans with different superscripts are significant (p<0.05) difference | |
As an increase of milk yield, daily yields of milk fat, protein, lactose and solids not fat were significantly higher (p<0.05) in group fed on S2 and S3 than control. Data of milk composition showed that milk fat, protein and lactose contents were slightly higher (p>0.05) in animals fed on treated silages than control. El-Sayed (2002) and Abo El-Nor and Kholif (2005) found similar results with goats fed on sodium acetate supplemented rations. These results indicate the same trend of silage quality, nutrient digestibility values and rumen parameters which lead to higher utilization of nutrients and higher digestible nutrients reach to mammary gland for milk constituents synthesis. Generally, feed efficiency calculated as milk yield/DMI and 4% FCM/DMI were improved by S3 followed by S2 and then S1 (Table 6).
Blood Serum Parameters
Animals fed on treated silage have a higher value of serum glucose content
than control animals (Table 7) which was in accordance with
the results of Clark et al. (1977) who claimed a positive correlation
between blood glucose and milk yield. Treated silages tended to decreased serum
urea content while, S3 decreased (p<0.05) serum total lipids and
increased (p<0.05) Glutamic-Oxaloacetate-Transaminase (GOT) contents compared
with control.
Animals fed on treated silage have a slightly higher (p>0.05) total protein,
albumine and Glutamic-Pyruvate-Transaminase (GPT) than animals fed on control
silage. These results indicated that supplementing formic acid or sodium acetate
to VFMW silage for lactating goats were not affecting on liver activity or animals
health.
| Table 6: | Average daily milk yield and composition of goats fed on experimental rations |
| A,B,CMeans with different superscripts are significant (p<0.01) difference; a,b,cMeans with different superscripts are significant (p<0.05) difference | |
| Table 7: | Effect of experimental treatments on some blood serum parameters of lactating goats |
| a,b,cMeans with different superscripts are significant (p<0.05) difference | |
CONCLUSIONS
It could be concluded that supplementing formic acid or sodium acetate to VFMW silage for lactating goats improved silage quality, nutrients digestibility, dry matter intake, rumen activity, feed efficiency and increased milk production and composition with no deleterious effect on general health of the treated animals as compared to animals fed the control silage.