Effects of different  levels and  sources of crude protein supplementation on feed intake, digestibility and nitrogen retention in swamp buffaloes compared to local cattle

Pham Tan Nha, Nguyen Van Thu and T R Preston^*

 College of Agriculture, Cantho University, Vietnam
ptnha@ctu.edu.vn
* Finca Ecológica, TOSOLY,  AA# 48 Socorro, Santander, Colombia
 

Abstract    

Four growing buffaloes (mean LW 226 kg) and four growing local cattle (mean LW 145 kg) were allocated to 4 diets according to 2*2 factorial within  a double Latin square design (one for each species).  The main coarse feed was para grass (1% body weight, DM basis) and rice straw fed ad libitum. The supplements were 150g and 200g crude protein (CP)/100kg LW/day from Sesbania grandiflora foliage and urea, or from cottonseed cake. The periods on each diet were 28 days with measurements of digestibility and N balance over the last 6 days.

DM intake did not differ between cottonseed meal and sesbania/urea supplementation; but was higher for the 200g CP level than the 150g level. There were no differences between species when DM intake was expressed on the basis of metabolic live weight but daily weight gain was higher for buffaloes. The DM and NDF apparent digestibilities were higher in buffaloes than in cattle (53 vs. 49.9 % and 57.9 vs 54.0%).. Crude protein apparent digestibility did not differ between species but was higher for the higher level of CP supplementation. Ruminal NH₃-N concentration was higher with the 200g CP level than with 100 g CP, both before and 3 hours after feeding.

It is concluded that cottonseed meal and foliage of Sesbania grandiflora plus urea have similar properties in providing rumen fermentable nitrogen and bypass protein for cattle and buffaloes fed rice straw and grass basal diets. Apparent digestibility coefficients were higher for DM and NDF in buffaloes than in cattle. N retention was also higher and this was reflected in higher live weight gains for the buffaloes. There was no difference in N retention between species when expressed on basis of metabolic live weight (W^0.75).

Key words: Buffaloes, cattle, cottonseed, digestibility, rice straw, sesbania, urea

Introduction

Cattle and buffaloes play an important role for small farmers for providing milk, meat and draught power. When cattle and buffalo are kept under similar conditions, it has been reported that buffaloes digest feed more efficiently than cattle, the difference being typically 2 to 3 percentage units higher (Wanapat 2001). Several experiments in India reported that ruminal characteristics of buffaloes are more favorable to ammonia-nitrogen utilization (Ludri and Razdan 1987, cited by Ligda 1998).  Buffaloes digested less crude protein than cattle in one trial but increased their body nitrogen more and they were being fed only 40% of the recommended daily intake of crude protein.  Thu (2005) suggested that the better performance of buffaloes fed coarse fodder may not be related to a superior capacity for fiber digestion, but rather  that they are less discriminating against plants not readily eaten by cattle.

Rice straw is a roughage with a low content of essential nutrients and low digestibility and usually fed to buffaloes and cattle as a main diet during the dry season in many Asian countries. These diets result in low performance and poor health. It has been suggested that supplements which increase ruminal ammonia concentrations and provide bypass protein are necessary to improve performance on rice straw diets (Preston and Leng 1987). Combinations of cottonseed cake, Sesbania grandiflora and urea would appear to be appropriate as the source of such supplements.

The objective of the present study was to evaluate the effect of different levels of crude protein derived from urea plus foliage of Sesbania grandiflora or cottonseed cake on the rumen NH₃-N concentration, apparent digestibility and nitrogen retention of swamp buffaloes in comparison to local cattle.

 

Materials and methods 

Treatments and design

Four growing swamp buffaloes and four growing local cattle with average live weight of 200 kg for buffaloes and 145 kg for cattle were allocated in two 4*4 Latin squarea(one for each species). The treatments in each square were arranged as a 2*2 factorial, the factors being:

Source of crude protein: Cottonseed cake (CS) or foliage of Sesbania grandiflora plus urea

Level of crude protein: 150 or 200 g crude protein per day/100 kg live weight. 

Feeding and management

The main coarse feed was para grass (Brachiaria decumbens) fed at 1% body weight (DM basis) and rice straw offered ad libitum. The supplements were 150g and 200g crude protein (CP)/100kg LW/day from Sesbania grandiflora foliage and urea, or from cottonseed cake. The experiment was carried out at the experimental farm of Cantho University. The animals were fed for 4 weeks on each diet including an adaptation period of 22 days and 6 days of collection of data. The supplements were fed at 06:00h and 15:00h, followed by part of the roughage on each occasion. At the last feed at 18.00h the remaining roughage was fed. The residues of feed were collected and weighed every morning the next day. Water offered and refused was also measured daily.  During the 6-day collection period, feeds offered and refused, faeces and urine were collected daily, weighed and pooled weekly for analysis.

Chemical  analysis

The samples were analysed for DM, OM, CP, neutral detergent fibre (NDF), acid detergent fibre (ADF), ash and lignin (Table 1).  DM and nitrogen (N) were analysed according to the standard methods of AOAC (1990), NDF, ADF and ADL were determined by the methods of Van Soest et al (1991).

Digestibility and nitrogen balance 

Apparent digestibility coefficients for DM, OM, NDF and ADF, and nitrogen retention,  were determined  by the method indicated by McDonald et al (1998).  

Statistical analysis

The data were subjected to an analysis of variance (ANOVA) using the General Linear Model (GLM) procedure of Minitab 13.31. Sources of variation were: species, supplement, level, interaction species*level and error. When the F test  was significant  (p<0.05), Tukey’s test for paired comparisons was used (Minitab 13.31).
 

Results

Feed  intake and weight gain

DM intake as a function of live weight or metabolic live weight was higher for the higher level of crude protein with an indication (P=0.02 and 0.01) that it was also higher for cottonseed cake than for sesbania-urea (Table 2).

The buffaloes had higher DM intakes than cattle expressed as g/kg^0.75 (Table 3). Growth rates were higher for buffaloes than for cattle and there was a suggestion it was higher for cottonseed cake compared with sesbania-urea (P=0.26) and for the 200 g CP level compared with 150 g CP (P=0.24).

Apparent digestibility  

The apparent digestibilities of DM, NDF and ADF did not differ between sources or levels of the supplement (Table 2). There were differences for crude protein digestibility between levels of supplements (higher on the 200 CP level compared with 150) but not between sources. Dry matter and NDF digestibilities were higher in buffaloes compared to cattle (Table 3).

Nitrogen retention and rumen ammonia

Nitrogen retention did not differ between the two sources of crude protein, but was higher for the level of 200g CP than 150g. Nitrogen retention was higher for buffaloes than for cattle (Table 3) and was significantly related with live weight gain Figures 1 and 2).

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