Grazing intensity and stocking methods on animal production and methane emission by grazing sheep: Implications for integrated crop–livestock system

Abstract

Among the various sources with a potential negative impact on the environment, methane (CH 4 ) emissions from livestock origin have been highlighted as important for the agricultural sector. Research to mitigate CH 4 emissions and understand how integrated crop and livestock production systems may contribute to the reduction of greenhouse gases, is essential for the development of public policies for environmental preservation. We hypothesized that combinations of stocking methods and grazing intensities provokes differences in the quantity and quality of herbage ingested, thus altering animal production and CH 4 emissions by the grazing animal. Experiments were carried out in 2011 (Experiment 1) and 2012 (Experiment 2), when the production of pasture and CH 4 emissions from sheep were studied in a system that integrates soybean (Glycine max. (L.) Merr.) and maize (Zea mays L.) in the summer/autumn, in rotation with Italian ryegrass (Lolium multiflorum Lam.) in winter/spring. Two stocking methods (continuous or rotational) and two grazing intensities (herbage allowance: moderate and low, 2.5 and 5 times the potential daily dry matter intake, respectively) in a randomized complete block design with three replicates were studied. Lambs were used in the first experiment, while lactating ewes (all with a single lamb) were used in the second experiment. Average daily gain (ADG) of lambs was greater (P < 0.05) in continuous than in rotational stocking, regardless of grazing intensity (150 vs. 89 g day −1 and 241 vs. 209 g day −1 in Experiments 1 and 2, respectively). Ewe ADG did not differ (P > 0.05) between treatments. Live weight gain per hectare (LWGHA) showed the same response in both experiments, with greater LWGHA in moderate grazing intensity (P < 0.05). In Experiment 1, the dry matter intake (DMI) was on average 21% greater (P < 0.05) for continuous stocking than rotational stocking (1345 g day −1 vs. 1075 g day −1 , respectively), while in Experiment 2, no differences (P > 0.05) between stocking methods and grazing intensities were observed (1673 ± 83 g day −1 ). The CH 4 emissions per animal did not differ (P > 0.05) among treatments in both experiments (22.7 ± 1.0 and 39.9 ± 1.3 g day −1 , Experiments 1 and 2, respectively), but when expressed in g CH 4 kg ADG −1 emissions were on average 35 and 15% greater (Experiments 1 and 2, respectively) (P < 0.05) under rotational than continuous stocking, independent of grazing intensity (171 vs. 263 g CH 4 kg ADG −1

A biodiversity-friendly rotational grazing system enhancing flower-visiting insect assemblages while maintaining animal and grassland productivity

“…Zhu et al (2015) focused on rationed grazing system with cattle, sheep and goats and recorded different responses of six insect groups (grasshoppers, homopterans, beetles, dipterans, hemipterans and butterflies) according to the grazer species, without considering grassland or animal performance during the grazing season. Contrasting results were reported in other studies that focused only on grassland and animal performance under continuous and rotational grazing systems, without considering their effect on insect diversity (e.g., Savian et al, 2014).…”

Suprimento de Nitrogênio para Culturas de Verão pela Aplicação Antecipada em Azevém Pastejado por Ovinos

“…A fertilização do solo em 2013 foi realizada inteiramente durante a fase pastagem, no dia 27 de junho de 2013, com 75 kg de N e 60 kg ha -1 de P 2 O 5 e de K 2 O. Para o N aplicado em forma de ureia, a adubação realizada foi a metade da quantidade recomendada, que seria de 150 kg ha -1 de N, com objetivo de avaliar se a fertilidade do solo construída no longo dos 10 anos do experimento iria contribuir para o suprimento de N das culturas de verão (Barbosa et al, 2007;Lunardi et al, 2008;Savian et al, 2014).…”

“…Quanto ao efeito da exportação do N via produção animal do sistema sobre o INN, dados históricos desse mesmo protocolo experimental apontaram que o ganho de peso vivo por hectare na intensidade de pastejo moderada é maior do que na intensidade baixa (Barbosa et al, 2007;Macari et al, 2011;Savian et al, 2014). Por essa razão, menores ofertas de forragem poderiam resultar em maiores exportações relativas de nutrientes, uma vez que a quantidade de fertilizantes aplicada foi igual em todos os tratamentos.…”

“…Souza et al (2009) comentaram que são esperadas maiores perdas de C e N do sistema por respiração sob maior intensidade de pastejo tanto pelo animal em pastejo como pela respiração microbiana do solo. Da mesma forma, pode-se supor que não foi observada diferença no INN da cultura do milho entre os métodos de pastoreio (rotativo e contínuo) em razão da pequena diferença na produção animal entre os métodos (Barbosa et al, 2007;Macari et al, 2011;Savian et al, 2014), além da semelhança observada para MFR entre os métodos (Quadro 1). Dessa forma, não há diferença na exportação de N entre os métodos de pastoreio.…”

Social and ecological analysis of commercial integrated crop livestock systems: Current knowledge and remaining uncertainty

“…Land-based livestock integration enhances C-, N-, P-, and S-cycling (Acosta-Martínez et al, 2010;Archer and Smeins, 1991;Drinkwater et al, 1998;Soussana and Lemaire, 2014), but the impacts on carbon and nutrient accumulation remain strongly influenced by co-management factors such as N and P fertilization, tillage methods, rotation length and grazing intensity (de Faccio Carvalho et al, 2010;de Lima Wesp et al, 2016;Savian et al, 2014). SOC is usually highest under high N fertilization combined with no-till planting (Lal, 2004(Lal, , 2011Mazzoncini et al, 2011).…”