Citation of this paper

Effects of forage quality on feed intake, nutrient digestibility and nitrogen retention of post-weaning Saanen crossbred goats

Nguyen Binh Truong^1,2 and Truong Thanh Trung³

¹ An Giang University, An Giang, Vietnam
nbtruong@agu.edu.vn
² Vietnam National University Ho Chi Minh City, Vietnam
³ Can Tho University, Can Tho, Vietnam

Abstract

This study aims to evaluate feed intake, nutrient digestibility, and nitrogen retention of post-weaning goat. Four male Saanen crossbred goats at 2.68±0.21 months of age (13.1±0.83 kg) were arranged in a Latin square design with 4 treatments and 4 periods. The study was carried out from May to July 2023 at the experimental farm of An Giang University. Four treatments were four sources of rumen escape protein including cabbage waste (CW), Wedelia trilobata L. (WTL), Operculina turpethum vines (OTV), and Jackfruit leaves (JL). Goats were allowed 10 days for diet adaptation and 4-days for sample collection. The DM intake of experimental goats were affected by the treatments. The DM consumption of the diets were 413, 480, 610, and 740 g/animal/day for CW, WT, OTV, and JL treatments, respectively. The CP intake (g/animal/day) of JL treatment (108 g) was higher (p<0.05) than CW (63.6 g) and WT (71.1 g) but it was not different with (p>0.05) OTV treatment (89.7 g). The DM, OM, and CP digestibility were different (p<0.05) among the treatments with lower values for the JL treatment. The nitrogen retention (g/BW^0.75/day) was lower (p>0.05) for the CW, while the higher value was the JL treatment. Daily weight gain tended to be lower in CW and WTL than in OTV and JL treatments. The conclusion was that using the forage sources well for Saanen crossbred post-weaning goats from high to low were Jackfruit leaves, Operculina turpethum vines, Wedelia trilobata L., and cabbage waste.

Keywords: small ruminants, feeds, digestibility

Introduction

The goat is one of the ruminant species selected to keep in priority with browsing behaviors adapting to feeds from plants and advantage characteristics of drought stand (Nguyen Van Thu, 2018). According to Tripathi et al (2006), the quality and quantity of feed are the major constraints in increasing ruminant productivity under tropical conditions. However, developing and exploitating of local feed resources in the Mekong Delta is a good strategy to provide feeds for ruminants. The previous study showed that cabbage waste (Brassica oleracea), jackfruit leaves, Operculina turpethum vines, and Wedelia trilobataL. were good forage sources fed goats. However, Raymundo-Hernández et al. (2020) reported that good-quality forage has more degradation kinetics than low-quality forage on ruminal. The weaning period represents the most critical stress in indirectly improving ruminant performance. However, there are little data on the performance of post-weaning goats supplemented with local forage available to guide farmers in the Mekong Delta on how best to utilize these feed resources. Therefore, the hypothesis of this study is that the difference in forage feed could affect feed intake, nutrient digestibility, and nitrogen retention of goats in the post-weaning period.

Materials and methods

Location

This study was located at the experimental farm of the Animal and Veterinary science Department of An Giang University from May to July 2023. The chemical composition of experimental diets was analyzed at laboratory E205 of the Faculty of Animal Sciences, Agriculture University of Can Tho University.

Animals and experimental design

Four male Saanen crossbred goats with an average live weight of 13.1±0.83 kg at 2.68±0.21 months of age were arranged in a Latin Square design with 4 treatments and 4 periods.

The four treatments were different forage sources of rumen escape protein including cabbage waste, Wedelia trilobata L., Operculina turpethum vines, and Jackfruit leaves corresponding to CW, WTL, OTV, and JL treatments, respectively. The ingredients composition in this study was shown in Table 1.

Table 1. Ingredients composition used in this study
Ingredients (%DM)	Cabbage waste	Wedelia trilobata L.	Operculina turpethum vines	Jackfruit leaves

Maize starch	20.0	20.0	20.0	20.0
Elephant grass	20.0	20.0	20.0	20.0
Cabbage waste	58.4	-	-	-
Wedelia trilobata L.	-	58.4	-	-
Operculina turpethumvines	-	-	58.4	-
Jackfruit leaves	-	-	-	58.4
Urea	1.00	1.00	1.00	1.00
Premix	0.60	0.60	0.60	0.60

Feeding procedure

All the feeds were weighed before feeding and supplied separately to the experimental goats. In detail, the cornstarch, and urea were mixed with premix supplements before feeding. The cornstarch and elephant grass were fed at 20% dry matter consumption. Forage sources were fed ad libitum and drinking water was always available. Refused feeds were weighed each morning.

Measurements

Daily feed intakes, nutrient digestibility, nitrogen retention, and weight gain were measured and calculated.

Feed offered, refusals and feces were analyzed for dry matter (DM), organic matter (OM) and crude protein (CP) and ash contents according to the procedures of AOAC (1990). The protein solubility (PS) was determined by method of Whitelaw and Preston (1963). However, neutral detergent fiber (NDF) and acid detergent fiber (ADF) were analyzed by the procedure of Van Soest et al (1991).

This study was four periods. Each experimental period was 14 days including 10 days for adaptation and 4 days for sample collection of feces. Apparent DM, OM, CP, EE, NDF and ADF digestibility were employed according to McDonald et al (2010).

The total urine of experimental goats was taken and acidified using H₂SO ₄ solution for the determination of nitrogen as described by AOAC (1990).

The goats were weighed on two consecutive days at the beginning and end of each experimental period.

Statistical analysis

The data were analyzed using the ANOVA Linear Model (GLM) of Minitab Reference Manual Release 20. (Minitab, 2021). Then for the paired comparison of two treatments, the Tukey test was used in this study (p<0.05).

Results

Chemical composition of feeds

Table 2. Chemical composition of feeds (% DM basis) used in the experiment
Feeds	DM, %	In DM, %
Feeds	DM, %	OM, %	CP, %	PS, %	NDF, %	ADF, %

Maize starch	85.2	98.7	8.61	8.13	27.5	4.25
Elephant grass	13.8	90.3	8.14	4.90	64.6	40.9
Cabbage waste	7.46	86.9	15.0	6.06	29.4	25.1
Wedelia trilobataL.	15.5	89.0	13.8	5.07	42.3	32.5
Operculina turpethumvines	15.7	85.7	13.3	3.59	37.2	32.9
Jackfruit leaves	39.5	84.8	14.4	2.84	49.0	35.4
Urea	99.6		286

The values reported for the composition of the feed ingredients are within the range of values reported by other authors such as Lam Phuoc Thanh et al (2021) for Jackfruit leaves, Le Van Phong and Nguyen Van Thu (2018) for cabbage waste. The forage sources of rumen escape protein in the present study are shown in Photos 1, 2, 3 and 4.


Photo 1. Cabbage waste	Photo 2. Wedelia trilobata L.	Photo 3. Operculina turpethumvines	Photo 4. Jackfruit leaves

Feed and nutrient intakes

The nutrient intake is presented in Table 3, Figures 1 and 2.

Table 3. Feed and nutrient intake of experimental goats
Item	CW	WT	OTV	JL	SEM	p

Feed intake, g DM/head/day
Maize starch	91.3^b	107^ab	128^ab	147^a	9.630	0.03
Elephant grass	91.7^b	107^b	113^ab	141^a	6.170	0.01
Cabbage waste	222	-	-	-	-	-
Wedelia trilobataL.	-	256	-	-	-	-
Operculina turpethumvines	-	-	358	-	-	-
Jackfruit leaves	-	-	-	441	-	-
Urea	5.17	5.99	6.26	7.03	0.409	0.09
Premix	3.15	3.65	3.81	4.28	0.248	0.086
Nutrients intake, g DM/head/day
DM	413^b	480^b	610^ab	740^a	47.60	0.01
DM/BW, %	2.74^b	3.01^b	3.99^ab	4.73^a	0.270	0.007
OM	367^b	427^b	547^ab	649^a	41.60	0.01
CP	63.6^b	71.1^b	89.7^ab	108^a	7.020	0.02
PS	25.4	26.9	28.8	31.4	2.790	0.51
PS/CP, %	39.5^a	37.8^a	32.1^b	29.0^b	0.826	0.001
NDF	146^c	192^bc	254^b	345^a	17.60	0.001
ADF	94.1^c	127^bc	163^ab	214^a	13.00	0.003
Water intake, g//head/day	800	1,242	455	610	245.0	0.23
Output
Feces, gDM//head/day	114^c	166^bc	200^b	365^a	16.10	0.001
Urine, g//head/day	1,772^ab	2,045^a	1,239^ab	673^b	243.0	0.03
The CW, WTL, OTV, and JL corresponding to cabbage waste, Wedelia trilobata L., Operculina turpethum vines, and Jackfruit leaves, respectively. ^a,b,c Means within a row with different letters differ significantly (p<0.05)

Digestibility

Data of nutrient digestibility and digestive nutrition are provided in Table 4.

Table 4. Nutrient digestibility, and digestible nutrients of experimental goats
Item	CW	WTL	OTP	JL	SEM	p

Nutrient digestibility, %
DM	72.1^a	66.8^a	67.5^a	50.5^b	2.170	0.002
OM	74.6^a	68.4^a	68.7^a	53.5^b	2.040	0.002
CP	72.6^a	66.9^a	67.0^a	50.1^b	2.210	0.002
NDF	61.8	60.2	59.4	48.3	3.230	0.08
ADF	52.5	53.1	56.0	37.2	4.020	0.06
Digestible nutrient, g/head/day
DM	299	315	410	375	34.70	0.19
OM	275	287	374	348	30.50	0.16
CP	46.1	47.1	59.9	54.2	5.360	0.31
NDF	91.3^b	113^ab	150^ab	168^a	12.80	0.02
ADF	50.5^b	65.0^ab	91.1^a	79.6^ab	7.130	0.03
The CW, WTL, OTV, and JL corresponding to cabbage waste, Wedelia trilobata L., Operculina turpethum vines, and Jackfruit leaves, respectively. ^a,b,cMeans within a row with different letters differ significantly (p<0.05)

Nitrogen retention, and daily weight gain

Both nitrogen balance and weight gain are shown in Table 5, Figure 3 and 4.

Table 5. Nitrogen retention and daily weight gain of goats in different treatments
Item	CW	WTL	OTP	JL	SEM	p

Nitrogen balance, g/head/day
N intake	10.2^b	11.4^b	14.4^ab	17.3^a	1.120	0.02
N in feces	2.80^c	3.85^bc	4.77^b	8.61^a	0.381	0.001
N in urine	4.55	3.96	3.83	2.32	0.799	0.33
N retention, g/head/day	2.82^b	3.57^ab	5.75^ab	6.36^a	0.638	0.02
N retention g/W^0.75/day	0.366^b	0.452^ab	0.752^a	0.804^a	0.078	0.02
Live weight gain, kg
Initial live weight, kg	14.9	15.2	14.6	15.0	0.208	0.37
Final live weight, kg	16.0	16.2	16.0	16.4	0.205	0.41
Daily weight gain (g/day)	75.8	76.8	97.6	102	12.00	0.36
The CW, WTL, OTV, and JL corresponding to cabbage waste, Wedelia trilobata L., Operculina turpethum vines, and Jackfruit leaves, respectively. a,b,c Means within a row with different letters differ significantly (p<0.05)


Figure 1. Effect of sources rumen escape protein on DM intake per body weight	Figure 2. Effect of sources rumen escape protein on CP digestibility

Figure 3. Effect of sources rumen escape protein on nitrogen retention	Figure 4. Effect of sources rumen escape protein on daily weight gain

Discussion

Both cornstarch and elephant grass intake were different (p<0.05) among treatments. However, the proportion of cornstarch per DMI and elephant grass per DMI consumption were similar to the ingredients in Table 1. The nutrient intake was affected by forage sources. Lower (p<0.05) DM consumption (g/head/day) in cabbage waste (413 g) and Wedelia trilobataL. (480 g) were observed compared with Operculina turpethum vines (610 g), and Jackfruit leaves (740 g). Although, the similarity in the CP content of forage but DM consumption of goats was affected by physical appearance and smell. According to Rahman et al (2015), the forage had a significant positive effect on DMI of goat. The DM and OM digestibility (%) were gradually reduced from cabbage waste to Operculina turpethum vines treatment (p<0.05), however, they were not significantly different (p>0.05) among cabbage waste, Wedelia trilobata L. and Operculina turpethum vines treatment. Similarly, CP digestibility was decreased (72.6 - 50.1%) in this study. Although nutrient digestibility tended to reduce from cabbage waste to Wedelia trilobata L. , Operculina turpethum vines and Jackfruit leaves, however, nutrient consumption increased.

As a result, the nutrient digestibility was higher (p<0.05) for the DM, OM, and CP while NDF and ADF were different (p>0.05) among treatments but the lower value for the Jackfruit leaves treatment. Previously, the CP digestibility of goats fed 52.7% Jackfruit leaves in the diet was 58.6% according to Lam Phuoc Thanh et al (2021). Le Van Phong and Nguyen Van Thu (2018) reported that CP digestibility was 86.7% by using 31.3% cabbage waste in the diet of Bach Thao goat. This difference may be explained by the months of age of the goat in this study at post-weaning. To our knowledge, the proportion of PSI/CPI for JL and OTV was lower than for CW and WT treatments (Table 3). That means high insoluble protein escapes the rumen of JL treatment higher than OTV, WT and CW treatments. The cabbage waste has a higher urine output than other forage, which reduces the nitrogen retention of cabbage waste in the goats. Opposite, the urine output of JL treatment was lower than other treatments. Moreover, the nitrogen in urine is lower than in feces which is beneficial for the environment. The result of JL in this study was similar to that reported by Lam Phuoc Thanh et al (2021). Therefore, the daily weight gain (g/day) was gradually decreased from Jackfruit leaves treatment to cabbage waste treatment.

Conclusion

The conclusion was that using the forage sources for goats with Jackfruit leaves, Operculina turpethum vines and Wedelia trilobata L. gave better feed intake, nutrient digestibility, nitrogen retention, and weight gain compared to the cabbage waste.
Promisingly, utilization of local forge sources for goats should be applied due to the availability and lower cost.

Acknowledgements

The authors gratefully acknowledge the material support from An Giang University

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