Feed intake, digestibility, nitrogen retention and live weight change of swamp buffaloes in response to different sources of crude protein and levels of energy


Nguyen Van Thu 

Department of Animal Sciences

Faculty of Agriculture and Applied Biology, Cantho University

nvthu@ctu.edu.vn

Abstract

The objectives of the study were to investigate the effects of different nitrogen sources associated with energy in the diets on feed intake, digestibility, nitrogen retention and live weight change of swamp growing buffaloes. A cross-over design experiment of nitrogen sources and energy supplementation was done on four growing swamp buffalo at 2.5 years of age with 6 treatments at Cantho University of Vietnam. The treatments included urea and molasses (UM), cotton seed cake and molasses (CM), urea, sesbania leaves and molasses (USM), urea and sesbania (US), urea, cotton seed cake and molasses (UCM) and urea and cotton seed cake (UC). Buffaloes were fed natural grasses at a level of 0.80% body weight (DM basis), while rice straw was fed ab libitum. The average of crude protein content in the diet was 9.0% and the ratio of  non-protein nitrogen and protein nitrogen was 2:1 in the diet, while molasses was supplemented at a level of 1.0g per kg body weight of the buffaloes. Each experimental period was two weeks with the first week for adaptation while the second week for getting samples. The results showed that there were no significant differences in feed intake among the treatments, however the rice straw intake was higher for the UC and US treatments.  There were no differences in DM, OM, NDF, ADF digestbility and nitrogen retention among the treatments. The conclusion was that a combination of different nitrogen and energy sources should be used as supplements in the diets of growing buffalo to improve performance.

Key words: Nitrogen sources, energy supplementation, feed intake, digestibility, nitrogen retention, swamp buffaloes.

Introduction

The buffalo population has suffered serious reduction in numbers in the Mekong delta of Vietnam, while the demands for meat for human consumption have been increasing. To satisfy these requirements, buffaloes and meat are being imported from Cambodia, Laos and India. One of the reasons of the buffalo population reduction is a lack of land to grow fodder and lack of knowledge to develop suitable methods of supplementation of rice straw (Nguyen Van Thu 2003). Traditionally farmers feed their buffaloes natural grasses and other crop residues. In the dry season the buffaloes are mainly fed rice straw; however the limitation of energy and nitrogen content in the rice straw diets constrains the growth, working performance and health of buffaloes. Balancing the supply of nitrogen- and energy-yielding substrates to ruminal microbes has been proposed as a mechanism for maximizing the capture of ruminally degradable N and optimizing microbial growth rate and efficiency in ruminants (Valkeners 2004). Therefore, efficient synthesis of rumen microbial protein to enhance buffalo performance needs a synchronization of nitrogen sources and energy in the diets.

The aim of this study was to investigate effects on feed intake, digestibility and nitrogen retention of supplementation of rice straw with different nitrogen sources and different energy levels. .

Materials and methods

Four growing swamp buffaloes at two years of age (220-300kg) were allocated to a cross-over design experiment with six supplements. The treatments were:

• Urea and molasses (UM)
• Cotton seed cake and molasses (CM)
• Urea, sesbania foliage and molasses (USM)
• Urea and sesbania foliage (US)
• Urea, cotton seed cake and molasses (UCM)
• Urea and cotton seed cake (UC).

Rice straw was offered ad libitum while natural grass was fed at a level of 0.83% body weight (DM basis). Molasses was fed at 1.0g per kg body weight. The ratio of the amount of  protein and non-protein nitrogen was 1/2 and the average crude protein content in the diets was 9.0%.

The supplements were divided into two similar parts, then fed twice a day in the morning and in the afternoon. The experimental period was two weeks with the first week for diet adaptation and the second one for collection of data.

Analysis of feeds included dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE) and ash following  the methods in AOAC (1990).

Measurements were taken of daily intake of feed and water. Live weight of the buffaloes was taken every two weeks. Feces and urine were collected during the last 6 days of each period for determination of apparent digestibility and N retention (McDonald et al 1995).

The data were analyzed using the General Linear option of the ANOVA software in Minitab Release 13.21 (Minitab 2000). The Tukey test in the same software was used to compare means when the “F”  test was significant at P<0.05.

Results and discussion

The DM of the grass was higher and the CP lower (Table 1) than normal as the grass was cut at the end of the dry season. Both Sesbania and cottonseed cake had appreciable levels of ether extract .

Total DM intake did not differ among diets (Table 2). As expected,  intake of rice straw tended to be reduced when molasses was also fed.  Intakes of ME (calculated values) were higher on CM than on UM.

The apparent digestibility of DM, OM, NDF, ADF, nitrogen retention and daily weight gain were not different among the diets in the present study.

.  There were indications of higher N retention with cottonseed meal supplementation in the different basal diets (Figure 1).

Figure 1: Effects of cottonseed cake compared with no protein supplement (CMvsUM), with Sesbania and molasses (UCMvsUSM) and Sesbania (UCvsUS)

Conclusions

The conclusion was that a combination of different nitrogen and energy sources should be used as supplements in the diets of growing buffalo to improve performance.

Acknowledgments  

The study  was carried out at the farm of Cantho University, Vietnam and was funded by the MEKARN project, financed by sidaSAREC for which I am greatly indebted..

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