Nictemeral composition of corn plants: afternoon harvest decreases dry matter recovery and increases silage starch content and <i>in vitro</i> degradation

Tonin, Tiago João; Valle, Tiago Antonio Del; Pereira, Stela Näetzold; Skonieski, Fernando Reimann; Konzen, Giovana Luísa; Reis, Tássila Rúbia Moreira; Viégas, Julio

doi:10.1590/0103-8478cr20230547

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ANIMAL PRODUCTION • Cienc. Rural 55 (02) • 2025 • https://doi.org/10.1590/0103-8478cr20230547 linkcopy

Nictemeral composition of corn plants: afternoon harvest decreases dry matter recovery and increases silage starch content and in vitro degradation

Composição química de plantas de milho: colheita da tarde diminui recuperação de matéria seca e aumenta teor de amido na silagem e degradação in vitro

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT:

Plants’ physiology changes through the day because photoassimilates can increase water-soluble carbohydrate concentration in the afternoon compared to the morning. This study evaluated the harvest time effect on whole-plant corn silage morphological composition, particle size, fermentation profile, chemical composition, in vitro degradation, and estimated milk yield. A two-year agronomic assay was performed in a completely random design, and one experimental silo was produced by each parcel (n = 16). The afternoon harvest increased (P < 0.01) dry matter content compared to the morning harvest. Harvest time did not affect (P ≥ 0.32) corn grain, stalk, leaf proportion, and silage particle size. However, the morning harvest increased dry matter recovery (P = 0.01) and had no effect (P ≥ 0.10) on silage pH and concentrations of lactic and acetic acid compared to the afternoon harvest. In addition, afternoon harvest instead of morning harvest increased (P ≤ 0.05) silage starch, water-soluble carbohydrates, acid detergent lignin, and ether extract content and dry matter in vitro degradation. Controversially, treatments showed no effect (P ≥ 0.14) on silage energy concentration, estimated energy content, and milk yield. Thus, the morning harvest produces more silage dry matter, but the afternoon harvest improves corn silage’s nutritional value with no impact on estimated milk yield.

Key words:
chemical composition; fermentation profile; morphological composition; water-soluble carbohydrate

Item	------Harvest time¹-----			Crop Year²		SEM³		-------------Probabilities⁴------------
	Morning	Afternoon	I	II		H	C	H × C
Dry matter, g/kg as-fed	340	390	335	396	7.63	< 0.010	< 0.010	< 0.010
Productivity, ton. DM/ha	16.9	15.0	19.0	12.8	0.43	0.071	< 0.011	0.071
-----------------------------------------------------------Morphological composition, g/kg DM-----------------------------------------------------------
Grain	419	401	345	476	22.0	0.322	< 0.011	0.282
Stalk	267	270	335	202	7.60	0.760	< 0.013	< 0.010
Leaf	128	122	148	103	7.31	0.393	< 0.011	0.551
Cob	93.5	96.7	90.6	99.6	4.50	0.745	0.382	0.282
Straw	55.0	56.6	59.6	51.9	1.70	0.621	0.033	0.183
Senescent	39.5	37.9	24.0	53.3	4.90	0.821	< 0.010	0.832
Flower	7.50	11.0	8.00	10.5	0.70	0.020	0.051	0.490
Silage density, kg/m³	563	533	593	503	10.3	0.050	< 0.010	0.011

Item	-----Harvest time¹-----			-------Crop Year²-------			SEM³	-------------Probabilities⁴------------
	Morning	Afternoon	I	II		H	C	H × C
-------------------------------------------------------------------Penn State separator, g/kg------------------------------------------------------------------
> 19 mm	176	154	161	168	10.1	0.403	0.781	0.354
8 to 19 mm	414	444	437	430	9.80	0.225	0.521	0.471
< 8 mm	410	402	402	409	9.93	0.750	0.753	0.133
TPS⁵, mm	20.0	18.7	19.9	19.0	0.78	0.511	0.592	0.085
Silage pH	3.72	3.74	3.66	3.79	0.02	0.143	< 0.010	0.070
Lactic acid, g/kg DM	44.1	25.1	25.3	17.6	6.18	0.101	0.231	0.203
Acetic acid, g/kg DM	21.4	20.7	25.3	17.6	1.05	0.770	< 0.010	0.151
Dry matter recovery, g/kg	985	981	982	984	0.74	0.011	0.060	0.163

Item	-----Harvest time¹----		-----Crop year²-----		SEM³	------------Probabilities⁴------------
	Morning	Afternoon	I	II		H	C	H × C
------------------------------------------------------Chemical composition, g/kg DM, unless stated------------------------------------------------------
Dry matter, g/kg as-fed	347	382	318	411	6.30	0.010	< 0.010	0.010
Ash	38.5	37.9	38.8	37.6	0.50	0.563	0.192	0.611
Neutral detergent fiber	407	399	427	380	7.35	0.501	< 0.010	0.583
Acid detergent fiber	231	227	248	210	4.73	0.571	< 0.010	0.914
Acid detergent lignin	27.0	38.5	37.5	28.0	2.40	0.010	0.033	0.190
Starch	297	319	226	390	17.4	0.053	< 0.010	0.151
Water-soluble carbohydrates	22.2	26.3	24.6	23.9	1.00	0.025	0.701	0.251
Crude protein	74.7	74.6	81.9	67.4	1.80	0.970	< 0.011	0.413
Ether extract	44.4	48.3	50.4	42.2	1.31	0.041	< 0.010	0.252
-----------------------------------------------------------------In vitro degradation, g/100g-----------------------------------------------------------------
Dry matter	59.1	61.8	63.1	57.7	7.70	0.010	< 0.010	0.110
Neutral detergent fiber	27.3	27.6	34.0	20.9	13.8	0.933	< 0.011	0.100
Total digestible nutrients, g/kg	616	633	625	625	9.0	0.213	0.973	0.181
Net energy, MJ	5.86	6.07	5.86	6.03	0.02	0.144	0.165	0.083
Milk yield/DMI	1.22	1.29	1.24	1.26	0.03	0.151	0.643	0.090
Milk yield /area, ton/ha/year	20.3	18.1	21.6	16.9	0.97	0.140	< 0.010	0.091

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Universidade Federal de Santa Maria Universidade Federal de Santa Maria, Centro de Ciências Rurais , 97105-900 Santa Maria RS Brazil , Tel.: +55 55 3220-8698 , Fax: +55 55 3220-8695 - Santa Maria - RS - Brazil
E-mail: cienciarural@mail.ufsm.br

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[TFN1] ¹Harvest time: morning: corn whole-plant harvest at 07:00; and afternoon: corn whole-plant harvest at 18:00.

[TFN2] ²Crops year: I: 2016/2017; and II: 2017/2018.

[TFN3] ³SEM: standard error of mean.

[TFN4] ⁴Probabilities: H: Harvest time (morning vs. afternoon harvest); C: crop year effect (2016/2017 vs. 2017/2018); H × C: harvest time and crop year interaction effect.