Abstract: The objective of this study, was to determine the effect of fodder tree as fiber sources in a total mixed ration on feed intake, nutrient digestibility, chewing behavior and ruminal fermentation. Four Brahman-Thai native crossbred steers with an average initial body weight of 233.3+13.09 kg were randomly assigned in a 4x4 Latin Square Design. During each of four 21 days periods, the animals were fed 4 Total Mixed Rations that varied in the fiber sources: Corn cob as fiber sources (C-TMR, control), Burma padauk leave as fiber source (B-TMR), Rain tree leave as fiber source (R-TMR) and Siamese rough bush leave as fiber source (S-TMR). The results showed that feed intake, crude protein digestibility, chewing time and ruminal fermentation were significantly different among treatments (p<0.05). Dry matter intake of animal fed R-TMR, B-TMR had higher than S-TMR and C-TMR (control). In this study, R-TMR had lowest crude protein digestibility. The number of chewing had highest when animals fed B-TMR. At 2 h post feeding C-TMR had the highest NH₃-N, when compared with other TMRs. The fodder tree as a fiber source in the total mixed ration has positive effect on feed intake and chewing behavior. Therefore, fodder trees can be use as fiber sources in TMR, especially when acute shortage of conventional fiber sources.

INTRODUCTION

In recent years, feeding a Total Mixed Ration (TMR) for cattle has become widely accepted. The benefits of a TMR include increased milk production, enhanced use of low cost alternative feed ingredients, ability to control the forage concentrate ratio, lower incidence of metabolic and digestive disorders and reduced labor input for feeding (Spahr et al., 1993; Everson et al., 1976). Fiber source of TMR is very importance, because it can be affected feed intake, chewing activity, digestibility and production (Chumpawadee and Pimpa, 2008). Generally, silage, forage, rice straw, corn cop and hay are conventional roughages found in TMR. Due to the dry season have shortage fiber source for mixed TMR. Therefore, non-conventional roughage such as fodder tree is needed for fiber source in TMR. Although, they have the crucial parameters affecting fodder utilization, such as tannins saponin and non protein amino acids, which are toxic to rumen microbes or to the animal (Lowry et al., 1996). However, leaves of fodder trees should be used as fiber sources in TMR. Because of their feed are high content of protein, minerals and vitamins (Baloyi et al., 1997) and availability in the dry season. In addition, the toxic substance in leaves can be reducing by sun dry.

With respect to fodder trees, limited information is available on its use as a fiber source of TMR. The aim of this study, was to investigate feed intake, nutrient digestibility, chewing behavior and ruminal fermentation in beef cattle fed different fiber sources.

MATERIALS AND METHODS

Preparation of TMRs: The burma padauk (Plerocarpus Indicus), rain tree (Samanea Saman (Jacg.) Merr) and siamese rough bush (Streblus Asper) leaves and corn cop were used in this study. They were collected from the Mahasarakham province area in the Northeast of Thailand. Fresh samples were dried in a hot, dry air force oven at 65°C for 72 h and weighed. All feed samples were ground to pass through a 1 mm screen for chemical analysis. The feedstuff samples were analyzed for Dry Matter (DM), Crude Protein (CP) and ash (AOAC, 1990), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Acid Detergent Lignin (ADL) (Van Soest et al., 1991), the data used for feed formulation.

Table 1:	Feed formulation and chemical composition of dietary treatments
1C-TMR = Corn cob as fiber source, B-TMR = Burma padauk leave as fiber source, R-TMR = Rain tree leave as fiber source, S-TMR = Siamese rough bush leave as fiber source

Four TMRs were formulated, to have similar Total Digestible Nutrient (TDN), CP, NDF, ADF, but differ in fiber source (Table 1).

Animals and feeding: Four Brahman-Thai native crossbred steers an initial body weighs of 233.3 + 13.09 kg were used. The animals were dewormed using ivermectin and injected with AD3E vitamin-complex prior to undertaking the experiment. They were housed individuals pens and fed ad libitum at 7.00 and 19.00 h. Drinking water and mineral lick were offered and available at all time. Animals were randomly allocated to one of four treatments in 4x4 Latin Square Design with 21 days periods. The dietary treatment were Corn cob TMR (C-TMR, control), Burma padauk leave TMR (B-TMR), Rain tree leave TMR (R-TMR) and Siamese rough bush leave TMR (S-TMR). The experimental was carried out at the Division of Animal Science, Faculty of Veterinary and Animal Sciences, Mahasarakham University, Thailand. The animals were weighed at the beginning and end of each period.

Sample collection and preparation: The TMRs were randomly collected and composite prior to analyses. Composite samples of TMR were ground to pass through a 1 mm screen and the analyzed for DM, ash and CP (AOAC, 1990) NDF, ADF, ADL (Van Soest et al., 1991) and Acid Insoluble Ash (AIA) (Van Keulen and Young, 1977).

Fecal samples were collected by rectal sampling at 10.00 h for 3 consecutive days and composted. The feces were placed into an oven at 65°C for 72 h, weighed and ground to pass through a 1 mm screen and the analyzed for DM, ash CP, NDF, ADF and AIA. The AIA content in feed and fecal were used to calculated digestibility (Schneider and Flatt, 1975).

Rumen fluid (100 mL) was collected at the end of each sampling period at 0, 2, 4 and 6 h post feeding by stomach tube connected with a vacuum pump. Ruminal pH was measured immediately after sampling using pH meter (Handy Lab 1, CG842 Schott). Rumen fluid samples were then filtered through 4 layers of cheesecloth. Fifty milliliter of rumen fluid was acidified with 5 mL of 6 N HCl and centrifuged at 16,000 g for 15 min and the clear supernatant was stored in plastic tubes at -20°C prior to ammonia nitrogen (NH₃-N) analysis using the micro Kjeldahl methods.

Blood samples were collected from the jugular vein at the same time as rumen fluid sampling, using 10 mL heparinised vacutainers. The tube was gently inverted a couple of times and then kept in an ice box and later centrifuged at 5,000 g for 10 min. The plasma was then transferred into storage tube and labeled with date and animal identification and stored at -20°C until analysis of Blood Urea Nitrogen (BUN) using the Stanbio Urea Nitrogen (SUN) (Liqui-UV^® Procedure No.2020).

On day 18 and 19 of each period, chewing behaviors were monitored visually at all time. Total chewing time was calculated by the sum of eating time and ruminating time. Eating chew and Ruminating chew were measured by counting.

Statistical analysis: All data obtained from the trials were subjected to the general linear models procedure of Statistical Analysis System (SAS, 1996) according to a 4x4 Latin Square Design. Means were separated by Duncan New’s Multiple Range Test. The level of significance was determined at p<0.05.

RESULTS AND DISCUSSION

Feed intake and nutrient digestibility: Chemical composition analyses of the 4 TMRs are presented in Table 1. TMRs contained similar concentrations of DM, ash and CP. However, NDF and ADF content in S-TMR were slightly higher than others TMRs. Table 2 shows the feed intake and nutrient digestibility of TMRs. Dry matter intake was significant different (p<0.05) among treatments.

Table 2:	Feed intake and nutrient digestibility in beef cattle fed difference TMRs
a, b, c: Means within a row different superscripts differ (p<0.05), 1 C-TMR = Corn cob as fiber source, B-TMR = Burma padauk leave as fiber source, R-TMR = Rain tree leave as fiber source, S-TMR = Siamese rough bush leave as fiber source

Table 3:	Eating and ruminating behavior in beef cattle fed difference TMRs
a, b, c: Means within a row different superscripts differ (p<0.05), 1C-TMR = Corn cob as fiber source, B-TMR = Burma padauk leave as fiber source, R-TMR = Rain tree leave as fiber source, S-TMR = Siamese rough bush leave as fiber source 2 = DM intake (g day-1)/eating time (min day-1). 3 = DM intake (g day-1)/rumination time (min day-1)

Many dietary factors may influence dry matter intake in ruminant such as physical characteristics, ingredient and nutrient composition. In this study, dry matter intake was influenced by fiber source in TMRs. Dry matter intake of animal fed R-TMR, B-TMR had higher than S-TMR and C-TMR (control), respectively. This is due to fodder tree TMR had palatability and good physical characteristics than corn cob TMR. Additionally, the animals fed C-TMR and S-TMR had lower chewing time when compared with the B-TMR and R-TMR (Table 3). It is demonstrate that burma padauk leave, rain tree leave and siamese rough brush leave can be used as fiber source in TMRs.

Digestibility of DM, OM and NDF were not significantly difference (p>0.05) between the treatments. The current finding disagree with in vitro studies on the affect of fodder tree as fiber source in TMRs (Chumpawadee and Pimpa, 2009), who found that IVDMD and IVODM were significantly different (p<0.05) among treatment. The S-TMR gave the highest IVDMD and IVOMD. It was probably different condition on in vitro and in vivo.

Table 4:	Eating, ruination chews ruminated boli and boli characteristics in beef cattle fed difference TMRs
a, b: Means within a row different superscripts differ (p<0.05), 1C-TMR = Corn cob as fiber source, B-TMR = Burma padauk leave as fiber source, R-TMR = Rain tree leave as fiber source, S-TMR = Siamese rough bush leave as fiber source

However, crude protein digestibility was significant different (p<0.05) between treatment. Many factors may influenced crude protein digestibility; protein levels in the ration (Kawashima et al., 2003), protein source and nature of protein source providing the rumen undegradable protein (Milis and Liamadis, 2007) and protein fraction (Chumpawadee et al., 2007). Fernandez et al. (2003) reported protein source in TMRs was affected protein digestibility. In this study, R-TMR had lowest crude protein digestibility, it was possibly due to protein fraction of R-TMR have less proportion of non protein nitrogen, especially urea in the ration (Table 1).

Chewing behavior: Chewing behaviors variables are shown in Table 3 and 4. Chewing time was significantly different (p<0.05) among treatment. The animals consumed B-TMR and R-TMR had high chewing time. In contrast, animals consumed C-TMR and S-TMR had low chewing time. The incidence, probably due to C-TMR and S-TMR are small particle size and less physical effective NDF that may affect chewing time. Generally, total chewing time decreases as dietary forage NDF decreased (Beauchemin, 1991) or particle size decreases (Grant et al., 1990). Additionally, chewing time and rumination times approximated the lower values reported by Yang and Beauchemin (2006) and Oshita et al. (2008). When expressed chewing time kg^-1 of NDF intake, the animal fed B-TMR had highest. The result indicated that chewing time increased as increasing NDF intake.

Table 5:	Blood urea nitrogen, ruminal pH and ammonia nitrogen in beef cattle fed difference TMRs
a, b, c: Means within a row different superscripts differ (p<0.05), 1C-TMR = Corn cob as fiber source, B-TMR = Burma padauk leave as fiber source, R-TMR = Rain tree leave as fiber source, S-TMR = Siamese rough bush leave as fiber source

Number of chews, number of chews per kg NDF intake, number of chew per eating time, ruminated boli, ruminated boli per kg NDF intake, number of chews per bolus and number boli per rumination time was not significantly affected by fiber sources in TMR (Table 4), except for number of chews per rumination time. The number of chewing had highest when animals fed B-TMR. However, chewing time and number of chewing are in the normal range. The result suggested that fodder tree was not negatively affect chewing activity, when use as fiber sources in TMR. Generally, chewing activity was affected by effective fiber in the ration (NRC, 1989). Fodder trees are high in effective fiber; they therefore, not affect chewing activity.

Ruminal fermentation and blood urea nitrogen: Concentrations of NH₃-N and pH in rumen fluid were used to monitor the ruminal fermentation pattern (Table 5). The pH was not altered by fiber source in TMRs (p>0.05). When monitoring pH pattern at 0, 2, 4 and 6 h post feeding, the pH values were relatively stable at 6.3-7.0 and all treatment means were within the normal range that has been reported as optimal pH (6.0-7.0) for microbial digestion of protein (Hoover, 1986) and fiber digestion (Theodorou and France, 1993). Generally, rate and extent of carbohydrates degradation are influenced ruminal pH (Nocek and Russell, 1988). The large amount of soluble carbohydrate may reduce the pH of rumen fluid and this can affect the rate of fermentation of structural carbohydrate (Sutton and Alderman, 2000). In addition, ruminal pH was partly regulated by the NH₃-N concentration (Chanjula et al., 2004) and VFA concentration in the rumen (Stokes et al., 1991). In spite of, the NH₃-N in the rumen at 2 h post feeding was increased of all treatment (Table 5), but it did not alter ruminal pH. It was possibly, the buffering capacity can maintained the ruminal pH. The current results are in agreement with in vitro studies (Chumpawadee and Pimpa, 2009) that observed pH was not markedly affected by fiber sources in TMRs. Generally, fodder tree have high effective fiber. It was expected that they positively affect chewing activity and leading to normal rumen condition and digestion.

Ammonia nitrogen concentration was significantly different (p<0.05) among treatments at 2 h of sampling. The results are in agreement with in vitro studies (Chumpawadee and Pimpa, 2009) that observed an NH₃-N concentration was influenced by fiber source in TMRs. The difference in NH₃-N concentrations among treatments may have been related directly to urea and degradability of protein in the TMRs. However, NH₃-N concentration was in the optimal range for rumen ecology, microbial activity (Perdok and Leng, 1990; Wanapat and Pimpa, 1999). At 2 h post feeding C-TMR had the highest NH₃-N, when compared with other TMRs. When ammonia nitrogen is high it indicates that the soluble fraction of protein is also high. There was highly correlated between BUN and NH₃-N concentration in the rumen (Church, 1972). Thus, animals fed C-TMR were also high BUN (Table 5). It was possibly protein degradation is more rapidly than synthesis or imbalance of fermentable energy and nitrogen available, so ammonia will accumulate in the rumen fluid and absorbed in to the blood, carried to the liver and converted to urea.

CONCLUSION

Based on this study, it can be conclude that the fodder tree as fiber sources in TMRs have been affected feed intake, crude protein digestibility, chewing behavior and ruminal fermentation. The animals fed fodder tree TMR had positive affect on feed intake, chewing activities and ruminal fermentation. Therefore, burma padauk leave, rain tree leave and siamese rough bush leave can be use as fiber sources in TMR, especially when acute shortage of conventional fiber sources.

ACKNOWLEDGEMENTS

The authors would like to express their gratitude to all staff and my student for their invaluable help on the farm and laboratory. We are grateful to the Division of Animal Science, Faculty of Veterinary and Animal Science, Mahasarakham University for supporting experiment facilities. Financial support was provided by The Thailand Research Fund and Commission on Higher Education under the program ‘New Researcher Grant’.