Abstract #W159

Section: Forages and Pastures
Session: Forages and Pastures: General forages and forage systems
Format: Poster
Day/Time: Wednesday 7:30 AM–9:30 AM
Location: Gatlin Ballroom

# W159
Effect of reduced lignin alfalfa on forage quality at three harvest intervals.
Zhiqiang Li^*2, Zhenzhen Li², David Combs¹, Daniel Undersander¹, ¹University of Wisconsin, Madison, WI, ²China Agricultural University, Beijing, China.

The present study investigates the effect of reduced lignin on alfalfa quality. Two alfalfa cultivars [Roundup Ready (RR) and double stacked Roundup Ready and Reduced Lignin (RR/RL)] were harvested at intervals of 28, 33, and 35 d. All replicated plots were harvested for 2 regrowth periods in July and August, 2014. CP, aNDF, lignin, NDFD48 value of samples on DM basis were analyzed with NIRS method (FOSS 6500) using NIRSC 2012 Alfalfa Hay Equation. Statistical analysis was done as a 2 way ANOVA using SPSS 22. CP content was not different between RR and RR/RL (27.5 vs 28.0, P > 0.05) and declined with advancing maturity (P < 0.05). aNDF content was higher in RR than RR/RL (31.6 vs 30.1, P < 0.05) though differences among harvest intervals were not significant (30.8 vs 30.5 vs 31.1, P > 0.05. Lignin content was not significantly different between RR and RR/RL (5.6 vs 5.5, P > 0.05) or among harvest intervals (5.6 vs 5.6 vs 5.5, P > 0.05). The NDFD48 of RR/RL was significantly higher than RR (52.2 vs 50.5, P < 0.05) and that of 28d harvest interval was significantly higher than 33d and 35d levels (53.1 vs 50.2 vs 50.8, P < 0.05). No significant interaction occurred between variety and harvest interval for any of the above 5 indices. The iNDF, kd and total-tract NDF digestibility (TTNDFD) are shown in the table below. The reduced lignin alfalfa tended to be lower in iNDF and higher in kd though differences were not significant, but was significantly higher in TTNDFD (P < 0.012). It appears that RR/RL variety reduces the NDF content and improves NDFD48, and TTNDFD. Table 1.

Item	Interval	RR	RR/RL	Mean	P-value
Forage	Harvest interval	Forage harvest × interval
iNDF	28d	34.1	29.9	31.7^b	0.086	0.001	0.470
	33d	42.1	37.0	39.9^a
	35d	39.3	39.2	39.2^a
	average	38.7^a	35.1^a	36.8
Kd	28d	7.8	7.1	7.4^a	0.156	0.980	0.153
	33d	7.0	8.2	7.5^a
	35d	6.4	8.9	7.8^a
	average	7.0^a	8.0^a	7.6
TTNDFD	28d	53.0	56.3	54.9^a	0.012	0.010	0.849
	33d	46.3	51.9	48.7^b
	35d	46.8	51.1	49.2^b
	average	48.6^b	53.3^a	51.0

^abcMeans in rows or columns with different superscripts differ (P < 0.05).

Key Words: alfalfa, lignin, forage