Desert Research Center, DRC, Egypt
Almost the oldest scientific Center in Egypt.
It was established at 1950.
Effect of grazing activity and
supplementary feeding on energy
utilization by goats
By
Ahmed R. Askar, Ph.D.
Professor of Animal Nutrition
Desert Research Center, Cairo, Egypt
Maintenance energy
• Feed ----- 70% of the production cost.
• Maintenance ----- 70% of the feed cost.
• --------------------------------------------------
• Almost = 50% of the production cost
Maintenance energy
• There are many factors affecting the energy requirement for maintenance, such as
• Acclimatization, Patra et al. (2009), Helal et al. (2010)
• Feed quality, Mecawi et al. (2006, 2008), Nassar (2014), Askar et al. (2016)
• Feed intake level, Asmara et al. (2006, 2011, 2012), Helal et al. (2011), Askar et al. (2015), Askar (2016)
• Animal activity, Beker et al. (2009, 2010), Goetsch et al. (2010), Askar et al. (2013, 2015)
• etc
0
10
20
30
40
50
60
70
2400 0200 0400 0600 0800 1000 1200 1400 1600 1800 2000 2200
Time of day
Gra
zin
g,
min
.
T F
Confinement:
Almost: 10% of maintenance
Grazing:
Probably-up to 100% of maintenance
Animal Activity
Energy cost for grazing activity
Relationship between energy
Expenditure and energy
requirements
Gross energy
(heat of combustion)
Fecal energy Digestible energy
Urine energy Methane energy Metabolizable energy
Heat increment Net energy
Used for maintenance Used for production
Energy Expenditure (EE)
Gross energy
(heat of combustion)
Fecal energy Digestible energy
Urine energy Methane energy Metabolizable energy
Heat increment Net energy
Used for maintenance Used for production
Energy Expenditure (EE)
Gross energy
(heat of combustion)
Fecal energy Digestible energy
Urine energy Methane energy Metabolizable energy
Heat increment Used for maintenance
Used for production
Energy Expenditure (EE)
Estimate of pasture intake, composition and digestibility
Internal marker
Feces samples
•Hand-plucked forage •Individual plant species
•Simulated grazed samples
Freeze dried then ground and analyzed for internal markers
Metabolizable Energy Intake (MEI)
Metabolizable Energy Intake (MEI)
Energy Expenditure (EE)
• Energy expenditure has been determined under
controlled or confinement conditions by
measuring oxygen consumption, and carbon
dioxide and methane production (Brouwer, 1965)
or by only oxygen consumption (McLean, 1972)
in respiratory chambers conditions,
• Expensive
• These conditions are not necessarily reflected
those of grazing animals or in group.
• Cannot follow the animal outside the chamber
Heart Rate (HR) Monitor
• Another potential means of assessing EE by
unrestrained animals is measurement of heart rate
(HR), which has been applied with sheep
(Barkai et al., 2002; El-Meccawi et al., 2008,
2009), cattle (Brosh et al., 1998, 2002), goats
(Puchala et al., 2003,2007; Helal et al., 2010),
and Camels (Askar et al., undergoing).
Heart Rate (HR) Monitor
Hear rate
Monitor (HR)
Indirect
Way
BUT
After
its calibration
To get
EE / HR
ratio
How to get the EE / HR ratio:
Energy expenditure will be measured from O2 consumption and CO2 and CH4 production (Brouwer, 1965), while simultaneously measuring HR with a Polar monitor (24 hours).
Head box
Respiratory calorimetry system
Flowkit 500
CO2, CH4, and O2 analyzers
Air dryer
The face mask open-circuit
respiratory system in DRC
Data collection and integration
McLean (1972)
Energy Expenditure (EE) = 20.53 x O2 consumption
Effect of grazing activity and
supplementary feeding on energy
utilization by goats
• Effect of grazing activity:
• In-door vs. Grazing
• Effect of supplementation:
• With vs. Without
concentrate supplement
MATERIALS AND METHODS
TREATMENTS
IN-DOOR vs. GRAZING
SUPPLEMENTATION
YES YES NO
In-door animals were fed alfalfa hay and supplementation
Grazing animals were grazing fresh alfalfa with or without
supplementation
Supplementation (Concentrate supplement) =
50% of the Metabolizable Energy for Maintenance (MEm)
33 3330
10
15
20
25
30
35
40
In-door
with
Grazing
with
Grazing
without
Body weight, kg
RESULTS AND DISCUSSION
*
53
64 64
10
20
30
40
50
60
70
In-door
with
Grazing
with
Grazing
without
Forage intake, g/kg BW0.75
RESULTS AND DISCUSSION
*
6469
58
20
30
40
50
60
70
80
In-door
with
Grazing
with
Grazing
without
Dry matter digestibility, %
RESULTS AND DISCUSSION
c
a b
1.41.5
1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
In-door
with
Grazing
with
Grazing
without
Gross energy, MJ/kg BW0.75
RESULTS AND DISCUSSION
0.931.07
0.69
0.20
0.40
0.60
0.80
1.00
1.20
In-door
with
Grazing
with
Grazing
without
RESULTS AND DISCUSSION
c
a b
Digestible energy, MJ/kg BW0.75
In-door
with
Grazing
with
Grazing
without
Body weight, BW (kg) 33.8 33.8 33.4
BW 0.75 14.0 14.0 13.9
EE (MJ / day) 6.93 6.82 6.72
EE (kJ / kg BW 0.75) 495 487 484
Heart rate (HR) 79.2 78.5 77.7
EE / HR ratio 6.25 6.20 6.22
Calibration of the heart rate monitor with a face mask open-circuit respiratory system
In metabolic (individual) cages
In-door
with
Grazing
with
Grazing
without
EE / HR ratio 6.25 6.20 6.22
HR (Beat / min) 106c 121b 131a
EE (kJ / kg BW 0.75) 660c 751b 819a
Calculation of the energy expenditure with grazing and in-door goats
In the current experiment (in group)
*
Effect of grazing activity and supplementary feeding on energy expenditure (EE, kJ/ kg
MBW/day)
Energy expenditure,
kJ/kg MBW/day
500
550
600
650
700
750
800
850
900
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hours of the day
In-door Grazing with supplement Grazing without supplement
In-door
with
Grazing
with
Grazing
without
EE / HR ratio 6.25 6.20 6.22
HR (Beat / min) 106c 121b 131a
EE (kJ / kg BW 0.75) 660c 751b 819a
Calculation of the energy balance with grazing and in-door goats
EE / ME intake ratio 87b 86b 144a
In-door
with
Grazing
with
Grazing
without
EE / HR ratio 6.25 6.20 6.22
HR (Beat / min) 106c 121b 131a
EE (kJ / kg BW 0.75) 660c 751b 819a
Calculation of the energy balance with grazing and in-door goats
EE / ME intake ratio 87b 86b 144a
EB (kJ / kg BW 0.75) 96.4a 120a -251b
Estimate energy expenditure in
natural rangeland
Gross energy
(heat of combustion)
Fecal energy Digestible energy
Urine energy Methane energy Metabolizable energy
Heat increment Used for maintenance
Retention energy
=
used for production
Gross energy
(heat of combustion)
Fecal energy Digestible energy
Urine energy Methane energy Metabolizable energy
EE for grazing activity
+ HP for lact. Preg.,
tissue accretion, etc
Used for maintenance
Retention energy
=
used for production
• Grazing animals have higher intake and
digestibility than those in the confinement.
• The concentrate supplement improved the
forage utilization for grazed animals.
• Grazing activity has a significant effect on the
energy expenditure and requirements, while
supplementary feeding is essential to maintain
grazing animals without deterioration under the
experimental condition.
CONCLUSION
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