Proceedings Buffalo Workshop December 2001

Estimation of rumen microbial protein production from urinary purine derivatives in local buffalo in Vietnam

Le Duc Ngoan, Nguyen Xuan Ba and Vo Kim Thanh

Faculty of Animal Sciences,

Hue University of Agriculture and Forestry, Hue

Introduction

The purine excretion technique has been developed and used to estimate microbial protein supply in European breeds of cattle and sheep (Chen et al 1990; Balcells 1991). Species differences in purine metabolism of ruminants are attributed to the level of endogenous purine excretion, the utilization ability of exogenous purine and enzyme profiles which are involved in purine degradation (Chen et al 1990, 1996). There is evidence to suggest that the excretion of urinary purine derivatives (PD) in Zebu cattle and water buffaloes differs from those of European cattle (Liang et al 1994). Liang et al (1999) found that endogenous PD excretion rates were lower in KK cattle than in swamp buffalo. However, there is little information about the purine excretion technique in Vietnam (Ngoan et al 1999).

Materials and Methods

The experiments were carried out in the University farm and in Huong Van village of Thua Thien Hue province in 1999.

Experiment 1. Response of urine excretion to feed intake and measurement of the proportion of plasma purine derivatives excreted in the urine of buffalo

There were 4 male buffaloes of 240 kg LW allocated to 4 treatment diets of 40, 60, 80 and 95% of ad libitum feeding level. The diet was based on young maize forage (stem and leaves), which contained 20% DM and 93% OM and 1.5 to 1.9% N in the DM. Each period lasted 21 days, in which 11 days were for adaptation and 10 days for urine and faeces collection.

Expiment 2. Spot urine collection in buffaloes

There were 30 buffaloes of average 408 kg initial body weight kept in individual farms in Huong Van village. The animals were fed the traditional diet (Not-supplemented) based on natural grasses, which was followed by traditional diet plus rice bran (Supplemented). Spot samples of urine were collected according to IAEA guidelines (1997).

Results and Discussion

Experiment 1. Response of urine excretion to feed intake and measurement of the proportion of plasma purine derivatives excreted in the urine of buffalo

Decreasing the feeding level from 95 to 60% of ad libitum intake did not affect digestibility of DM and OM, and did not affect urinary N. However, N retention decreased significantly (p<0.05) (Table 1). At the feeding level of 40% of ad libitum, the value of N retention was negative.

Table 1. Feed intake, organic matter digestibility and N-balance in buffaloes
	Feeding level, % of ad libitum				SEM/P
	40	60	80	95
Daily intake, kg
DM	1.9	2.9	3.8	4.5
OM	1.8	2.7	3.6	4.2	0.5/0.0001
DOM	0.85	1.42	2.16	2.65	0.5/0.0001
Digestibility, %
DM	41^a	55^b	55^b	60^b	12/0.0001
OM	47^a	59^b	60^b	63^b	2.1/0.003
N, g/day
Intake	35.0	52.5	69.5	81.8	1.9/0.005
Digested	21.3	36.8	49.6	59.3	05/0.0001
In urine	21.7	21.4	21.2	23.4	1.37/0.001

The feeding level between 40 to 80% of ad libitum intake did not affected excretion rate of allantoin, uric acid and total PD in urine (p<0.05), but the level of 95% increased these indicators (Table 2).

Table 2. Mean live weight and daily PD and creatinine excretion in swamp buffalo under different feeding levels
	Feeding level, % of ad libitum				SEM/P
	40	60	80	95
LW, kg	247	244	246	239
LW^.75	62.3	61.7	62.1	60.8
Allantoin, mmol/W^.75	220^a	239^a	242^a	299^b	12.72/0.004
Uric acid, mmol/W^.75	81.1^a	70.8^a	64.5^a	151.5^b	13.2/0.03
Total PD, mmol/W^.75	301^a	310^a	307^a	451^b	23.1/0.003
Creatinine, mmol/ W^.75	1.05	0.87	0.86	0.99	NS

Experiment 2. Spot urine collection in buffaloes

Supplementation of farm-based tradition diets with rice bran led to significantly higher daily feed intake, and concentrations in urine of allantoin, uric acid and creatinine (Table 3).

Table 3. Excretion of purine derivatives and creatinine in buffaloes kept in farm
	Not-supplemented	Supplemented
Body weight, kg	413	429
W^.75, kg	91.6	94.3
Intake, kg DM/day	4.5	6.1
Allantoin, mg/litre	21.5	32.0
Uric acid, mg/litre	7.2	8.4
Creatinine, mg/litre	660	722
N, mg/litre	5.8	5.1

References

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