Response of elephant grass to grazing under an organic production system

Bratz, Vinicius Felipe; Olivo, Clair Jorge; Fernandes, Julia Aires; Seibt, Daiane Cristine; Alessio, Vinicius

doi:10.5935/1806-6690.20190019

Brasil

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Animal Science • Rev. Ciênc. Agron. 50 (1) • Jan-Mar 2019 • https://doi.org/10.5935/1806-6690.20190019 linkcopy

Response of elephant grass to grazing under an organic production system¹

Resposta do capim elefante sob pastejo em sistema de produção orgânica

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The aim of this research was to evaluate elephant grass under an organic and a conventional system. Under the organic system, species with complementary growth periods were combined; elephant grass was planted in rows 3.0 m apart and ryegrass was sown between the rows of elephant grass during the winter period, with spontaneous species being allowed to develop during the summer period. For the conventional production, two types of pasture were studied: one using the same strategy as for the organic production, and the other with a monocrop of elephant grass. Under the conventional and organic systems, 120 kg of N ha^-1 were applied as chemical and organic fertiliser (cattle manure and pig slurry) respectively. Holstein cows were used in the evaluation. The experimental design was completely randomised, with three treatments (forage systems), three replications (paddocks) and measurements repeated over time (season). During the experimental period (370 days), nine grazing cycles were carried out under the organic and conventional systems (elephant grass in association with other forages) and eight grazing cycles under the conventional system (a monocrop of elephant grass). Forage production was 31.6, 32.8 and 24.2 t ha^-1, and the stocking rate was 3.4, 2.1 and 4.6 AU ha^-1 day^-1 under the respective systems. Better results for forage production and distribution were found under the organic and conventional systems including a mixture of forages. The best results for leaf to stem ratio in the elephant grass and for stocking rate were seen under the monocrop system.

Key words: Apparent forage intake; Grazing efficiency; Rotational stocking; Pennisetum purpureum; Forage production systems

FS	Season				Mean	CV (%)
FS	Winter	Spring	Summer	Autumn	Mean	CV (%)
Pasture forage mass (t DM ha^-1)
Org¹ 1 Organic production system with a mixture of forages;	3.7 a	6.0 a	11.2 a	9.2 a	7.5	5.1
Conv1² 2 Conventional production system with a mixture of forages;	3.0 b	5.6 a	9.0 b	7.4 b	6.2	6.2
Conv2³ 3 Conventional production system with a monocrop of elephant grass. Lowercase letters in a column and uppercase letters on a row differ by Student's t-test (p≤0.05); DM = dry matter; CV = coefficient of variation	2.5 c	2.7 b	6.1 c	4.8 c	4.9	9.6
Mean	3.0 D	4.8 C	8.8 A	7.1 B
CV (%)	2.8	6.1	7.2	7.6
Elephant grass (t DM ha^-1)
Org	1.8 b	2.9 ab	6.5 a	5.5 a	4.1	6,8
Conv1	1.7 b	3.2 a	6.0 a	4.4 a	3.8	7,4
Conv2	2.3 a	2.7 b	6.1 a	4.5 a	3.9	7,3
Mean	1.9 D	2.9 C	6.2 A	4.8 B
CV (%)	6.4	4.4	7.6	8.7
Elephant grass senescent matter (t DM ha^-1)
Org	0.4	0.3	0.2	0.2	0.3	13.3
Conv1	0.5	0.4	0.2	0.3	0.3	16.3
Conv2	0.2	0.0	0.5	0.3	0.2	27.4
Mean	0.3	0.1	0.1	0.3
CV (%)	12.4	23.8	28.1	14.5
Ryegrass (t DM ha^-1)
Org	0.4	0.3	-	-	0.4 a	13.5
Conv1	0.2	0.1	-	-	0.2 b	20.6
Mean	0.3	0.2
CV (%)	14.8	18.2			16.3
Other grasses (t DM ha^-1)
Org	0.7	1.9	3.8	2.5	2.2	12.3
Conv1	0.4	1.8	2.3	2.2	1.7	14.3
Mean	0.5 C	1.9 B	3.1 A	2.3 B
CV (%)	23.3	12.3	9.7	11.2
Other species (t DM ha^-1)
Org	0.2	0.4	0.3	0.1	0.3	14.0
Conv1	0.1	0.2	0.2	0.2	0.2	20.9
Mean	0.2	0.3	0.3	0.1
CV (%)	30.7	19.3	20.1	30.5
Dead matter between rows (t DM ha^-1)
Org	0.3	0.3	0.5	1.0	0.5	11.3
Conv1	0.2	0.2	0.3	0.4	0.3	14.6
Mean	0.2 B	0.3 B	0.4 A	0.7 A
CV (%)	10.4	9.3	6.1	25.3
Elephant grass leaf to stem ratio
Org	2.0	4.3	4.0	1.8	3.0 b	17.8
Conv1	0.8	5.0	3.5	1.4	2.7 b	26.1
Conv2	3.1	8.5	7.5	2.1	5.3 a	12.3
Mean	2.0 B	5.9 A	5.0 A	1.8 B
CV (%)	24.8	8.0	19.4	29.2	17.0

FS	Season				Mean	CV (%)
FS	Winter	Spring	Summer	Autumn	Mean	CV (%)
Pasture forage mass (t DM ha^-1)
Org¹ 1 Organic production system with a mixture of forages;	3.0 a	5.0 a	6.0 a	5.2 a	4.8	4.8
Conv1² 2 Conventional production system with a mixture of forages	2.1 b	3.0 b	2.9 b	2.8 b	2.7	8.3
Conv2³ 3 Conventional production system with a monocrop of elephant grass. Lowercase letters in a column and uppercase letters on a row differ by Student's t-test (p≤0.05); DM = dry matter; CV = coefficient of variation	1.5 c	1.3 c	1.6 c	1.5 c	1.5	15.5
Mean	2.4 B	3.1 A	3.5 A	3.2 A
CV (%)	5.4	6.4	6.9	12.8
Elephant grass (t DM ha^-1)
Org	1.2 a	2.3 a	2.7 a	2.5 a	2.2	6.2
Conv1	1.0 b	1.3 b	1.2 b	1.0 b	1.1	12.0
Conv2	1.1 ab	1.2 b	1.4 b	1.2 b	1.2	11.1
Mean	1.2 B	1.6 A	1.8 A	1.6 A
CV (%)	4.5	14.2	7.6	10.3
Elephant grass senescent matter (t DM ha^-1)
Org	0.5 a	0.3 a	0.5 a	0.3 a	0.4	12.6
Conv1	0.6 a	0.2 b	0.2 b	0.2 a	0.3	18.5
Conv2	0.4 a	0.1 b	0.2 b	0.3 a	0.3	18.4
Mean	0.5 A	0.2 B	0.3 B	0.3 B
CV (%)	11.7	26.2	20.7	22.1
Ryegrass (t DM ha^-1)
Org	0.2	0.2			0.2 a	11.1
Conv1	0.1	0.1			0.1 b	16.2
Mean	0.2	0.1
CV (%)	12.9	13.4			13.2
Other grasses (t DM ha^-1)
Org	0.6 a	1.4 a	2.2 a	1.9 a	1.5	7.1
Conv1	0.4 a	1.2 a	1.3 b	1.3 a	1.0	8.7
Mean	0.5 C	1.3 B	1.7 A	1.6 AB
CV (%)	13.9	7.7	4.3	15.6
Other species (t DM ha^-1)
Org	0.2	0.3	0.2	0.2	0.2 a	12.6
Conv1	0.1	0.1	0.1	0.1	0.1 b	25.1
Mean	0.1	0.2	0.1	0.1
CV (%)	26.6	23.1	22.6	25.0	20.1
Dead matter between rows (t de MS ha^-1)
Org	0.3	0.5	0.4	0.4	0.4	15.6
Conv1	0.2	0.3	0.3	0.3	0.3	22.2
Mean	0.2 B	0.4 C	0.3 AB	0.4 A
CV (%)	23.7	13.8	22.6	6.2

FS	Season				Mean or Production	CV (%)
FS	Winter	Spring	Summer	Autumn	Mean or Production	CV (%)
Rate of forage accumulation (kg DM ha^-1dia^-1)
Org¹ 1 Organic production system with a mixture of forages;	51.7	52.4	187.6	54.8	86.6 ab	11.9
Conv1² 2 Conventional production system with a mixture of forages;	61.3	70.8	199.5	73.0	101.2 a	11.6
Conv2³ 3 Conventional production system,with a monocrop of elephant grass. Lowercase letters in a column and uppercase letters in a row differ by Student's t-test (p ≤0.05); BW=body weight; DM=dry matter; AU=animal unit, 450kg; CV=coeficiente de variação. Period of evaluation=365, 325 and 345 days for the respective treatments	42.6	34.9	149.6	54.3	70.3 b	13.4
Mean	51.9 B	52.7 B	178.9 A	60.7 B
CV (%)	5.2	10.2	9.5	20.1	10.5
Accumulated forage prodution (t DM ha^-1)
Org	5.6 a	5.4 a	17.8 a	2.8 a	31.6 a	10.8
Conv1	4.5 b	6.7 a	17.5 a	4.1 a	32.8 a	9.9
Conv2	3.4 b	3.5 b	14.3 a	3.0 a	24.2 b	13.0
Mean	4.3 B	5.2 B	16.7 A	3.3 C
CV (%)	7.2	11.7	9.5	17.0
Grazing efficiency (%)
Org	33.0 c	34.0 b	46.0 b	43.5 b	39.0	12.8
Conv1	35.0 b	44.7 a	66.4 a	61.6 a	52.0	8.3
Conv2	39.3 a	49.6 a	73.7 a	68.4 a	57.8	7.3
Mean	35.8 C	42.8 B	62.0 A	57.8 A
CV (%)	5.5	7.2	3.5	8.3
Apparent forage intake (% BW)
Org	2.6	2.1	2.4	3.2	2.6	18.0
Conv1	2.5	2.9	3.7	3.6	3.1	13.3
Conv2	3.0	2.2	3.3	3.4	2.9	15.8
Mean	2.7 AB	2.4 B	3.1 AB	3.4 A
CV (%)	15.5	14.5	3.7	24.1
Stocking rate (AU ha^-1 day^-1)
Org	2.2 a	2.0 b	7.0 b	2.2 b	3.4	6.8
Conv1	1.7 b	1.8 b	3.5 c	1.2 c	2.1	12.3
Conv2	1.7 b	2.9 a	9.8 a	3.9 a	4.6	5.1
Mean	1.8 C	2.3 B	6.8 A	2.4 B
CV (%)	4.1	8.5	6.6	9.3

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