Citation of this paper

Soybean meal as source of rumen scape protein for fattening crossbred beef cattle

Nguyen Binh Truong^1,2 and T R Preston³

¹ An Giang University, An Giang, Vietnam
nbtruong@agu.edu.vn
² Vietnam National University Ho Chi Minh City, Vietnam
³ Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV), Carrera 25 No 6-62 Cali, Colombia

Abstract

The objectives of this experiment were to evaluate the effects of increasing levels of soybean meal as a source of bypass protein is in a diet for fattening crossbreed beef cattle, five male F1 crossbred beef cattle (F1 crosses with Zebu of Black Angus, Charolais, Droughtmaster, Red Angus and Wagyu) of 24.5±2.84 months of age with an average body weight of 359±40.1 kg were allocated to a 5x5 Latin square design. The treatments were of increasing levels of soybean meal of 0.6, 0.92, 1.26, 1.65, and 2.06 kg/d. The basal diet was commercial concentrate (2 kg/d), fresh Elephant grass (10 kg/d), and ad libitum rice straw. Experimental periods were of 21 days and for collection of feces during the last 7 days for determination of digestibility coefficients.

DM intake and live weight gain were increased, and feed conversion was improved, all with curvilinear trends, as the offer level of soybean meal was increased, the digestibility coefficient of DM and NDF were not affected by increasing levels of soybean and were thus unrelated to the improve productivity that resulted from soybean supplementation.

Key word: bypass protein, digestibility, metabolism

Introduction

Neither the breeds available nor the feeding systems were appropriate for modern methods of beef production (Preston and Willis 1974; Preston and Leng 1987). The breeds available in the largest numbers were the breed Bos indicus and the feeding system. Although It did quit for animals providing mainly power in agriculture these this breed was adequate. However for beef production, the requirement is for animals with faster rates of growth producing tender meat both of which required hey change both of the breed and of the feeding system. These trends and now being manifested in activities such as artificially insemination with selecting the breeds and improvements in the feeding system. On this latter issue it has been proposed (Preston et al 2021) that's the key factor in the design of diets or fattening cattle is the supply of bypass protein (diet protein that will escape the rumen fermentation to be digested in the intestine by mammalian enzymes). The following experimet was planned to test the hypothesis.

Materials and methods

The experiment was carried out at Sau Duc cattle farm, located in Vinh Gia commune, Tri Ton district of An Giang province.

Five male F₁ crossbred beef cattle (Black Angus x Zebu crossbred, Charolais x Zebu crossbred, Droughtmaster x Zebu crossbred, Red Angus x Zebu crossbred and Wagyu x Zebu crossbred) at 24.5±2.84 months of age with an average body weight of 359±40.1 kg were used in a 5x5 Latin square design. The treatments were increasing levels of soybean meal of: 0.6, 0.92, 1.26, 1.65 and 2.06 kg/d. The basal diet was: commercial concentrate (2 kg/d), fresh Elepphant grass (10 kg/d) and ad libitum rice straw.


Photo 1. Black Agnus x Zebu crossbred	Photo 2. Red Agnus x Zebu crossbred

Photo 3. Charolais x Zebu crossbred

Photo 4. Droughmaster x Zebu crossbred	Photo 5. Wagyux Zebu crossbred

The Elephant grass was grown on the farm. Rice straw was purchased from local farmers. The concentrate and soybean meal were bought from a Feed Company. The concentrate and the soybean meal were fed at 7:00 am and again at 1:00 pm. The Elephant grass was fed at 8:00 am and again at 2:00 pm. Rice straw was always available. Before beginning the experiment all animals were treated for external and internal parasites with Ivermectin and given Albendazole, respectively.

Feeds offered and refusals were analyzed of dry matter (DM), organic matter (OM) and crude protein (CP) and ash following the procedure of AOAC (1990), neutral detergent fiber (NDF) was determined according to Van Soest et al (1991).

Experimental periods were 21 days with 14 days for adaptation to the new treatment followed by seven days collection of feces to determine digestibility coefficients.

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

The data were analyzed using the ANOVA Linear Model (GLM) of Minitab Reference Manual Release 16.1 (Minitab, 2010). Response curves were fitted to the data for feed intake, live weight gain and feed conversion using the polynomial equations in the Excel program of Microsoft Office software.

Results

Feed characteristics

The values reported for the composition of the feed ingredients are within the range of values reported in Feedipedia.org.

Table 1. Chemical composition of feeds (% DM basis) used in the experiment
	DM %	% in DM
	DM %	OM	CP	NDF	Ash

Soybean extraction meal	86.3	93.5	41.5	19.3	6.52
Concentrate	86.1	90.9	15.9	36.4	9.13
Elephant grass	14.2	88.1	8.13	62.5	11.9
Rice straw	83.1	87.8	5.41	69.0	12.2
DM: dry matter, OM: organic matter, CP: crude protein, NDF: neutral detergent fiber

Animal performance

DM intake and live weight gain were increased, and feed conversion was improved, all with curvilinear trends, as the offer level of soybean meal was increased (Table 2: Figures 1-3).

Figure 1. Feed intake is increased with a curvilinear trend as the
feeding level of soybean meal was increased

Table 2. Effect of protein levels on feed and nutrient intakes of beef cattle in the experiment
Item	Soybean meal, kg/d					SEM	p
Item	0.6	0.92	1.26	1.65	2.06	SEM	p

Feeds offered, kg/d
Soybean meal	0.60	0.92	1.26	1.65	2.06^a
Concentrate	1.72	1.72	1.72	1.72	1.72	-	-
Elephant grass	1.42	1.42	1.42	1.42	1.42	-	-
Rice straw	3.87	3.7	3.92	3.64	3.29
DM	7.62^c	7.86^bc	8.32^ab	8.44^a	8.49^a	0.104	0.000
DM: dry matter, a, b, c values with different superscript letters within one row are significantly different at the level of 5%.

Table 3. Mean values for feed intake, live weight changes and DM feed conversion
Item	Soybean meal, kg/d					SEM	p
Item	0.6	0.92	1.26	1.65	2.06	SEM	p

Live weight, kg
Initial	403	399	398	401	399	2.36	0.61
Daily gain, g	560^b	901^ab	1,043^a	1,002^a	1,112^a	92.8	0.011
Feed intake	7.62^c	7.86^bc	8.32^ab	8.44^a	8.49^a	0.104	0.000
FCR	13.61	8.72	7.98	8.42	7.63
DM: dry matter, OM: organic matter, CP: crude protein, NDF: neutral detergent fiber, FCR: feed conversion ratio a, b, c values with different superscript letters within one row are significantly different at the level of 5%.


Figure 2. Live weight gain was s increased with a curvilinear trend as the feeding level of soybean meal was increased	Figure 3. Feed conversion was improved with a curvilinear trend as the feeding level of soybean meal was increased

Digestibility

Increasing the level of soybean meal in the diet increased the digestibility of protein but had no effect on the digestibility of dry matter, organic matter or neutral detergent fiber (Table 4). The positive effect on protein this digestibility can be expected as supplementations with highly digestible (soybean meal) reduced the relative effect of the Elephant grass, rice straw – both of low digestibility.

Table 4. Apparent nutrient digestibility and daily weight gain of cattle in different treatments.
Item	Soybean meal, kg/d					SEM	p
Item	0.6	0.92	1.26	1.65	2.06	SEM	p

Digestibility, %
DM	61.0	61.5	63.6	62.4	63.8	1.439	0.603
OM	63.8	64.1	65.3	64.9	66.0	1.405	0.805
CP	71.9^c	74.4^bc	78.2^ab	80.1^a	81.6^a	1.050	0.000
NDF	65.1	63.1	65.2	63.1	63.5	1.418	0.699
DM: dry matter, OM: organic matter, CP: crude protein, NDF: neutral detergent fiber ^{a, b, c} values with different superscript letters within one row are significantly different at the level of 5%.

Discussion

The dramatic impact of the soybean meal supplement (weight gain was doubled and the feed required per unit live weight gain was halved) confirmed the key role of a source of bypass protein in fattening diets for beef cattle of high genetic merit for growth, as employed in this experiment. The high gain rate of live weight (1.11 kg/d) reflected the benefits of crossbreeding with established beef cattle breeds on the response to the highest level of supplementation with soybean meal.

Digestibility coefficients of DM and NDF were not affected by increasing levels of soybean, indicating that the improved growth and feed conversion were achieved mainly by an improved balance of nutrients at sites of metabolism and only partially by increases in feed intake.

Conclusion

Live weight gain and feed conversion were increased 100%, with curvilinear trends, as the offer level of soybean meal was increased from 0.6 to 2.06 kg/d.
Digestibility coefficient of DM and NDF were not affected by increasing levels of soybean, indicating that the improved growth and feed conversion were achieved mainly by an improved balance of nutrients at sites of metabolism and only partially by increases in feed intake.

References

AOAC (Association of Official Analytical Chemists) 1990 Official methods of analysis (15th edition). Washington, DC, 1: 69-90.

Minitab 2010 Minitab reference manual release 16.2.0, Minitab Inc.

Preston T R and Willis M B 1974 Intensive Beef Production. Pergamon Press, Oxford, UK

Preston T R and Leng R A 1987 Matching Ruminant Production Systems with Available Resources in the Tropics and Sub-Tropics. http://www.cipav.org.co/PandL/Preston_Leng.htm

Preston T R, Leng R A, Phanthavong V and Gomez M E 2021 Fattening cattle with tropical feed resources; the critical role of bypass protein. Livestock Research for Rural Development. Volume 33, Article #86. http://www.lrrd.org/lrrd33/7/3386prest.html

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary fiber, and nonstarch polysaccharides in relation to animal nutrition. Symposium: Carbohydrate methodology, metabolism and nutritional implications in dairy cattle. J. Dairy Sci. 74, pp. 3585-3597.