The slides compare and describe the differences between meta-analysis and systematic review in scientific research

1. Meta-analysisofexperimentaldata
inpigandbroilernutrition
Damilola Uthman Kareem
Lecturers:
Prof. Nilva Kazue Sakomura
Prof. Marie-Pierre Létourneau
Montminy

2. Meta-analysis
Title:
Effect of low-protein corn and soybean meal-
based diets on nitrogen utilization, litter quality,
and water consumption in broiler chicken
production: insight from meta-analysis
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3. Objective(s)of
themeta-
analysis
 To categorize the nutritional strategies described in the
selected low-protein literatures;
 To quantify the impact of these strategies on Nitrogen
balance, daily water consumption, litter quality and
plasma uric acid; and
 To determine the main interfering factors of these
highlighted responses.
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4. ArticleSources
Keywords: broiler, poultry and
protein
Keyword searches: (crude protein OR amino
acids) AND (chick OR broilers NOT layer)
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5. Articlefiltering
Inclusion criteria
 the study specified a control dietary CP level and a low-protein treatment
supplemented with the limiting amino acid;
 the experimental diet composition was listed in detail;
 the diet formulations were iso-energetic;
 the experimental conditions (bird variety, sex, age, number per treatment,
ambient temperature, etc.), feed intake and weight gain were provided.
56 publications
Year in consideration:
1990 - 2017
Prisma flow diagram of the selection procedure for broiler diet studies
Source: Alfonso-Avila et al. (2022)
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6. Coding andData
Homogenization
DATA CODING
 The experiments were encoded independently, each
including at least two dietary treatments (e.g. low protein and
control).
 Studies with results for more than one growth phase were
assigned two codes, one for 0–21 d (grower) and another for
22–42 d (finisher).
DATA
HOMOGENIZATION
 In order to homogenize the nutritional profile of each
experimental diet and to complete missing data, INRA
feedstuff tables (Sauvant et al., 2004) were used to
recalculate the complete nutrient profile based on ingredient
composition.
 Amino acid standardized ileal digestibility was calculated
using Rostagno et al. (2017).
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7. Database
Creation
NB: Attention was paid to the meta-design which is determined by the
structure of the experiments for each predictor variable (Sauvant et
al., 2008), while the relationship between two independent variables
taken two by two was examined graphically to assess the extent of
variation in each experiment and to identify outliers. All collinearities
were identified.
Nitrogen balance
(39 articles - 144
trials, 319
treatments
Daily Water
Consumption (7
articles - 19 trials,
49 treatments
Litter moisture
(8 articles - 13
trials, 31
treatments
Uric acid (8
articles - 18
trials, 58
treatments
Variables: ADG, ADFI, FCR, N
intake, N retention, N exretion, N
efficiency, Daily water
consumption, litter moisture and
Uric acid
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8. StatisticalAnalysis
 All statistical analyses were carried out using the MIXED model
(Minitab, version 18, State College, PA, USA). The bird age (grower,
finisher) and provision of amino acid at levels meeting requirements or
not (binary coding 0 or 1) were analyzed as fixed effects as follows:
Where;
Yij is the value of the dependent variable Y in experiment i with dietary treatment j
µ is the overall intercept, µi is the effect of the experiment group i on the intercept µ
with the condition that the sum of each µi is equal to 0, αi is the age effect,
ᵦi is the amino acid requirement effect, b1 and b2 are the linear and quadratic
coefficients of the relationship, and Ɛij is the residual error.
The interactions between CP, trial and age were also tested. Differences between
treatments were considered significant at P < 0.05, and a tendency to differ was
declared when P < 0.10.
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9. Result- Part
Source: Alfonso-Avila et al. (2022)
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10. Systematic
Review
Title:
Factors that Influence the Production,
Environment, and Welfare of Broiler Chicken: A
Systematic Review
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11. Objective(s)of
thesystematic
review
 To characterize the scientific publications on the topics
of the factor that influences broiler production
published between 2000 and 2015 in journals indexed
in the databases of Google Scholar, Scielo, and
ScienceDirect.
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12. ArticleSources
Keywords: commercial broilers, production,
lodging conditions, thermal environment, air
environment, acoustic environment, luminosity,
handling, thermal stress
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13. Phasesof review
process
Scheme of the systematic review process of scientific articles considered in the current
study. (Adapted from Rodrigues Filho & Gonçalves, 2015).
Inclusion and exclusion criteria
Source: Baracho et al. (2018)
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14. Breakdown of
publications by
source,year and
language
Total articles
(167)
Articles
considered (34)
Articles discarded
after critical
systematic review
(133)
Prisma flow diagram
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15. Result
Source: Baracho et al. (2018)
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16. Differences
betweenmeta-
analysis and
systematic review
S/N Meta-analysis Systematic review
1 The data obtained after data
filtering, coding etc are subjected
to statistical analysis (variance-
covariance, PCA, multiple
regression, simple linear
regression, Pearson correlation
etc.) to generate model(s) that
inform(s) meaningful conclusions
The data obtained after data
filtering are not subjected to
statistical analyses. The results
from the selected articles are
discussed as is, and conclusions
made based on inferences drawn
from the articles.
2 It requires coding of the variables
for easy statistical analysis
Since statistical analysis is not
required, coding is not necessary
3 It is more rigorous, and requires
the researcher to have a good
command of statistical analysis
and interpretation.
A researcher does not necessarily
need to know how to carry out
statistical analysis, but however, be
able to interprete statistical results.
The following differences were observed
between meta-analysis and systematic review
from the two articles above;
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