Abstract #M168

Section: Forages and Pastures (posters)
Session: Forages and Pastures I
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Exhibit Hall A

# M168
Nutritional value of the tropical legumes cowpea, lablab, and canavalia.
E. E. Corea Guillén^*1, J. M. Flores Tensos¹, E. A. Martinez Aguilar¹, E. A. Perez Medina¹, G. S. Acevedo Cuellar¹, E. A. Alas García¹, D. Vyas², K. G. Arriola², G. A. Broderick³, ¹Departamento de Zootecnia, Facultad de Ciencias Agronómicas, Universidad de El Salvador, San Salvador, El Salvador, ²Department of Animal Sciences, University of Florida, Gainesville, FL, ³Broderick Nutrition and Research LLC, Madison, WI.

Tropical forages often have poor nutritional value for dairy cattle, necessitating concentrate feeding to meet animal needs. Feeding tropical legume forages is a strategy for improving nutritional value of diets at reduced cost and external dependence. A study evaluated relative nutritional value of 3 tropical legumes: cowpea (Vigna sinensis L.), lablab (Dolichos lablab L.), and canavalia (Canavalia ensiformis L.) as potential forages. Crops were grown in 4 replicated plots during the dry season under irrigation and harvested 70 d after planting; yield was estimated in a 9-m² area in each plot. Whole plant was separated into leaves and stems; fractions were dried, ground (1 mm screen) and analyzed for CP and NDF. Ruminal DM digestibility (DMD) was estimated after 48 h by incubating samples in vitro in Ankom bags in triplicate in gas-tight culture bottles at 39°C and by incubating samples in situ in nylon bags in triplicate in a cannulated dairy cow. Data were analyzed in a random model using Infostat; results are in Table 1. No difference was detected in DM from whole plant, whereas leaves from canavalia and lablab had greater CP content than cowpea. Content of NDF was lower, and ruminal DMD greater, in all cowpea fractions. Leaves from lablab tended to have greater DM digestibility. Composition and digestibility differences among these species reflect differences in nutritional value. Cowpea was the most promising species because of higher DMD, probably due to lower NDF content. Table 1. Forage composition and digestibility

Item	Cowpea	Lablab	Canavalia	SEM	P-value
DM, %
Whole plant	16.2	16.9	16.4	0.20	0.743
Stem	14.9^b	15.9^b	34.0^a	6.19	<0.001
Leaves	19.2^b	19.7^b	28.2^a	2.9	<0.001
CP, % DM
Whole plant	17.9	16.4	18.6	0.64	0.429
Stem	9.9	9.2	9.6	0.21	0.579
Leaves	23.7^b	29.6^a	27.6^a	1.74	<0.001
NDF, % DM
Whole plant	50.0^b	54.2^a	51.8^ab	1.23	0.020
Stem	52.7^c	62.2^b	66.6^a	4.10	<0.001
Leaves	33.7^b	38.6^a	35.4^b	1.45	0.090
Ruminal in vitro DMD, %
Whole plant	70.4^a	61.4^b	59.1^b	3.44	<0.001
Stem	68.1^a	49.5^b	41.3^b	7.93	<0.001
Leaves	68.2	77.4	63.1	4.2	0.065
Ruminal in situ DMD, %
Whole plant	76.2^a	62.0^b	67.7^b	4.13	<0.001
Stem	68.1^a	58.3^b	48.1^c	5.75	<0.001
Leaves	84.4^a	83.6^a	80.3^b	1.26	0.003

^a–cMeans with different superscripts differ (P < 0.05).

Key Words: dry matter digestibility, tropical legume