The article continues the discussion begun in the last issue of the onsin Crop Manager and uses other data describing the relationship between corn maturity and silage yield and quality

Corn silage yield and quality changed substantially during the growing season (Table 1). At V11 crude protein was 18% and one ton of silage could produce 1700 lb of milk. Like all crops, corn silage quality decreased as the crop approached flowering, i.e. milk per ton decreased from 1700 lb/T on V11-14, to 1300 lb/T on R1.0 (silking), and was lowest at R3.0 (Milk) at 700 lb/T. Milk per ton and milk per acre then increased throughout the remainder of the growing season. During the silking and milk stages, milk per acre and milk per ton was about 1/3 of the optimum harvest dates between R5.5 and R5.8.

Late planted immature corn resulted in lower yield and quality than early planted corn harvested around R5.5 (Table 2). Little grain was produced on corn planted after June 22 even with shorter-season hybrids. Milk per acre and milk per ton of immature corn was about 1/3 that of corn harvested at R5.5 to R6.

Points to consider with immature corn:

Immature corn is too wet to ensile and will seep out of the storage structure lowering silage quality.
To produce good quality silage with adequate yields, corn must be past the R4.5 to R5 stage of development. Corn which immature should be fed to heifers or other less productive animals.

Table 1. Corn silage yield and quality response to harvest date for Pioneer 3578 during 1993 at Arlington, WI. Corn was planted on May 11. Derived from Burger and Hudelson (1993) and Undersander et al. (1993).
Harvest	Corn development	Whole plant moisture	Dry matter yield	Crude protein	ADF	NDF	Milk production
date	stage	%	T/A	%	%	%	lb/T	lb/A

July 11	V11	92	1.1	18	28	49	1700	1900
July 21	V14	90	2.2	15	27	50	1700	3800
July 31	R1.0	85	3.8	12	31	55	1300	5000
August 10	R2.0	83	5.0	11	33	58	1100	5500
August 20	R3.0	84	5.7	10	36	65	700	3700
August 30	R4.0	82	6.4	10	33	60	1000	6500
September 10	R5.0	76	8.0	9	27	51	1700	13400
September 21	R5.5	75	8.6	9	25	48	1900	16300
October 5	R5.8	66	8.2	8	21	43	2300	18800
Corn development stage: Vn = nth leaf collar; R1 = Silking; R2 = Blister; R3 = Milk; R4 = Dough; R5 = Dent; R5.5 = 50% kernel milkline; R5.8 = 80% kernel milkline; R6 = Black layer (physiological maturity).

Table 2. Corn silage yield and quality response to planting date during 1994 at Arlington, WI. Corn was harvested near R5.5 or after a killing frost. Derived from Lauer and Hudelson (1994) and Undersander et al., (1993).
Hybrid	Planting	Corn development	Whole plant moisture	Dry matter yield	Crude protein	ADF	NDF	In vitro digest.	Milk production
	date	stage	%	T/A	%	%	%	%	lb/T	lb/A

Pioneer 3417	May 11	R5.6	62	8.2	7	24	45	79	2100	16900
(108 d RM)	May 31	R5.5	55	7.4	7	28	52	75	1600	11700
	June 22	R5.0	71	4.8	9	32	59	73	1100	5300
	July 11	R2.0	79	2.7	10	33	62	68	900	2500

Pioneer 3751	May 11	R5.8	58	7.8	7	24	46	79	2000	15800
(98 d RM)	May 31	R5.5	58	8.3	7	26	49	77	1800	15000
	June 22	R5.0	65	2.6	9	29	55	76	1400	3700
	July 11	R2.0	76	2.2	10	31	60	73	1100	2400

Pioneer 3921	May 11	R6.0	52	6.6	7	23	44	76	2200	14200
(85 d RM)	May 31	R5.6	64	6.9	7	26	47	77	1900	13000
	June 22	R5.0	66	1.3	8	33	59	69	1100	1400
	July 11	R4.0	74	2.4	10	32	61	69	1000	2400
Corn development stage: R2 = Blister; R3 = Milk; R4 = Dough; R5 = Dent; R5.5 = 50% kernel milkline; R5.8 = 80% kernel milkline; R6 = Black layer (physiological maturity).