Influence of phenological stage on fresh forage, hay and silage on nutritional value of tall wheatgrass

Abstract Text:

The objective was to compare the nutritional value of two methods of forage conservation and fresh forage (type of forage=TF) of tall wheatgrass (Thinopyrum ponticum) in 5 different phenological stages (PhS). The experimental units were 5 m² plots randomly distributed upon a uniform stand of tall wheatgrass in a complete randomized design (n=3). Clipping dates were 113, 142, 163, 190 and 211 d after regrowth related to the stages vegetative (V), booting (B), anthesis (A), milk (M) and dough-grain (D) respectively, on standing fresh pasture (P), hay (H) and silage (S). Clipping was mechanical at 10 cm height and dry matter yield (DMY) was measured. Subsamples from each experimental unit were used for: (1) DM determination of P, (2) preparation of H by drying sheltered at environmental temperature (72 h), and (3) preparation of S in PVC cylinders with 2 kg fresh forage carrying capacity (60 d). All materials were analyzed for NDF, ADF, ADL, soluble non structural carbohydrates (SNSC), IVDMD and CP. Data was analyzed by ANOVA and means compared by Tukey (α=0.05). Results are reported in the Table. A significant interaction TF X PhS was found for all variables with the exception of CP and ADL. Only A could be an adequate alternative for S. However, at B, A, M and D the H conservation method would preserve an appropriate nutritive value as well.

Table. Nutritional value (%) for tall wheatgrass at different PhS and for different TF.

PhS	TF	DM	NDF	ADF	ADL	SNSC	IVDMD	CP	DMY
V	P	38.0a	70.2	35.7	3.0	15.1a	52.4	12.6	1393a
	H	91.9b	67.5	35.8	2.6	13.1a	54.3	11.3
	S	41.7a	66.8	37.9	3.7	1.96b	50.9	11.2
B	P	36.1a	70.3a	36.3a	4.8	23.8a	55.4a	9.5	2047a
	H	91.6b	72.8b	38.5b	5.3	12.4b	47.0ab	10.0
	S	37.5a	70.9ab	40.1c	6.1	3.5c	38.9b	9.07
A	P	40.8a	72.1	38.7	5.3	24.2a	50.3	7.3	3215b
	H	92.4b	73.2	39.7	5.5	12.7b	46.3	8.1
	S	43.4a	71.6	41.2	6.1	1.2c	43.5	7.3
M	P	51.3a	68.4a	36.9a	5.0	18.8a	49.3a	6.6	3338b
	H	92.1b	71.8b	40.4ab	5.9	16.5a	48.4a	7.0
	S	50.6a	72.5b	47.0b	7.2	4.9b	40.7b	7.1
D	P	60.4a	72.1	43.7	6.3	17.7a	46.7	5.5	3812b
	H	92.9c	71.2	44.4	5.9	17.2a	49.8	5.7
	S	63.9b	71.4	45.3	6.0	11.8b	48.2	5.2

PhS: phenological stage; TF: type of forage.

^a,b,cDiffer within each PhS (P<.05)

Keywords: forage conservation, nutritional value, Thynopirum ponticum