Savian J.V.,Federal University of Rio Grande do Sul |
Neto A.B.,Federal University of Rio Grande do Sul |
Neto A.B.,Federal University of Paraná |
de David D.B.,State Foundation of Agricultural Research FEPAGRO |
And 8 more authors.
Agriculture, Ecosystems and Environment | Year: 2014
Among the various sources with a potential negative impact on the environment, methane (CH4) emissions from livestock origin have been highlighted as important for the agricultural sector. Research to mitigate CH4 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 CH4 emissions by the grazing animal. Experiments were carried out in 2011 (Experiment 1) and 2012 (Experiment 2), when the production of pasture and CH4 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. 89gday-1 and 241 vs. 209gday-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 (1345gday-1 vs. 1075gday-1, respectively), while in Experiment 2, no differences (P>0.05) between stocking methods and grazing intensities were observed (1673±83gday-1). The CH4 emissions per animal did not differ (P>0.05) among treatments in both experiments (22.7±1.0 and 39.9±1.3gday-1, Experiments 1 and 2, respectively), but when expressed in g CH4kgADG-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. 263g CH4kgADG-1 and 171 vs. 202g CH4kgADG-1 in Experiments 1 and 2, respectively). Stocking method was more important than grazing intensity in determining methane production by grazing sheep. Continuous stocking was the most efficient grazing management in reducing methane emissions per unit animal production. © 2014 Elsevier B.V.
David D.B.,State Foundation of Agricultural Research FEPAGRO |
Poli C.H.E.C.,Federal University of Rio Grande do Sul |
Savian J.V.,Federal University of Rio Grande do Sul |
Amaral G.A.,State Foundation of Agricultural Research FEPAGRO |
And 3 more authors.
Journal of Agricultural Science | Year: 2014
The current research was carried out to evaluate the use of crude protein and fibre components in faeces for estimating intake and digestibility in sheep fed with pearl millet (Pennisetum americanum (L.) Leeke). The equations were developed from four trials in metabolism cages with 16 sheep in each trial. Each animal received a different quantity of millet leaves in the diet: 0·015, 0·020 and 0·025 dry matter (DM) as a proportion of live weight (LW) and ad libitum with at least 0·2 of daily feed refusals. Organic matter intake (OMI, g/day) was measured, through the difference between offer and refusals; total faeces were collected for 5 days, which was used to determine faecal crude protein (CPf, g/day and g/kg of organic matter (OM)), faecal neutral detergent fibre (NDFf, g/day and g/kg OM), faecal acid detergent fibre (ADFf, g/day and g/kg OM) and OM digestibility (OMD). Linear regression equations were calculated to determine the relationship between OMI and CPf (P<0·001, R 2=0·90, relative prediction error (RPE=14·02%). A multiple linear equation was generated for OMI including CPf and NDFf (P<0·001, R 2=0·94; RPE=9·25%). Hyperbolic (single and multiple) and exponential models were tested to estimate OMD, where the hyperbolic multiple model including CPf and NDFf showed lower RPE (3·90%). These equations for estimating OMI and OMD were evaluated on sheep grazing P. americanum fertilized with increasing levels of nitrogen (N) (50, 100, 200 and 400 kg N/ha), comparing measured and estimated OMI. The intake estimated by multiple regression (CP and NDFf) showed a higher R 2 (0·98) and lower RPE (5·25%) than the simple (CPf only) linear equation (R 2=0·94; RPE=20·45%). The results demonstrated the feasibility of using the faecal index generated in metabolism cages for estimating intake and digestibility in sheep grazing P. americanum. © 2013 Cambridge University Press.
Azevedo E.B.,Federal University of Pampa |
Azevedo E.B.,Federal University of Rio Grande do Sul |
Azevedo E.B.,Massey University |
Poli C.H.E.C.,Federal University of Pampa |
And 8 more authors.
Livestock Science | Year: 2014
This research was carried out to evaluate the use of faecal components as markers to estimate intake and digestibility of Italian Ryegrass (Lolium multiflorum Lam.) of grazing sheep. The research had two phases. In Phase 1 seven indoor experiments were carried out using individual metabolic cages with 16 lambs in each experiment (four treatments with four animals each). Three phenological stages of the pasture (vegetative, pre-flowering and flowering) were evaluated and four different allowances of Italian Ryegrass, collected by grab sampling daily, of 1.5, 2.0, 2.5. kg of dry matter/100. kg of live weight and ad libitum. The indoor experimental design was completely randomized and the experiments were grouped according to the phenological stages. Organic matter intake (OMI, g/day), total daily production of faeces, faecal crude protein amount (fCP, g/day), faecal crude protein concentration (fCPc, g/kg of organic matter), faecal acid detergent fibre amount (fADF, g/day), faecal acid detergent concentration (fADFc, g/kg of organic matter) and organic matter digestibility (OMD) were assessed in the indoor experiment. In Phase 2, male sheep were used in two grazing experiments to graze Italian Ryegrass under different management conditions, which were herbage allowance, pasture phenological stage and rotational or continuous system. This phase was designed to validate the equations previously obtained. The stocking rate was controlled according the treatment defined, and the herbage mass, sward height, herbage and faecal chemical composition, OMI and OMD were measured. In Phase 1 significant linear regression equations were found between OMI and fCP in each phenological stage (P<0.05). The intake equations were compared by contrasts analysis and found to be different (P<0.001) between phenological stages, confirming the need to use the data separately by maturity stage. Two equations (simple and multiple hyperbolic) were tested for the relationship between OMD and fCPc, and the multiple hyperbolic, which includes fCPc and fADFc showed best accuracy. In Phase 2 the regression between the actual and estimated had a correlation coefficient of 0.94 and relative prediction error of 9.28%, showing the feasibility of using the generated equations. © 2014 Elsevier B.V.