Effects of Threonine Supplementation in Low Protein Diet
on Broilers Growth Performance and Biochemical Parameters
Fazila Wadood1,
Muhammad Shoaib2*, Arshad Javaid2, Khalil Ur Rehman1,
Naureen Rana1, Fazal Maqsood3, Aadil Munir4
and Muhammad Ali Jawad2
1Department of Zoology, Wildlife
and Fisheries, University of Agriculture, Faisalabad, Pakistan
2Institute of Animal and Dairy
Sciences, University of Agriculture, Faisalabad, Pakistan
3Institute of
Soil & Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
4Computer Science Department,
COMSATS University Islamabad, Attock Campus, Pakistan
*For correspondence: shoaib.imtiaz43@gmail.com
Received 21 March 2022; Accepted 31 March
2022; Published 30 April 2022
Abstract
The present study was conducted to evaluate the effects
of graded levels of threonine (Thr) on growth performance and biochemical
parameters in broiler chickens. For this purpose, one-day-old 150 broiler
chicks were kept in pens at Poultry Farm of the University of Agriculture,
Faisalabad for 5 weeks. Chicks were divided into three treatments including T1
(control group), T2 (CP 1% less and Thr 10% extra) and T3
(CP 2% less and Thr 20% extra). Iso-caloric diets were formulated according to
two phases as a starter (1–21 days) and finisher (22–35 days). Treatments were
replicated into 5 subgroups having 10 chicks in each. Data collected were
analyzed by analysis of variance technique under CRD. Chicks fed diet contained
CP 1% less and Thr 10% extra had lower (P
< 0.05) feed intake, improved (P <
0.05) weight gain and FCR than those fed diet containing CP 2% less and Thr
20% extra. Dressing percentage was higher (P
< 0.05) in chicks fed a control diet. However, higher (P < 0.05) breast yield and lower (P < 0.05) production cost per kg live
weight were recorded in birds fed diet contained CP 1% less and Thr 10% extra
than other groups. Different treatments had no effect (P > 0.05) on relative organ weight. Chicks fed diets having
reduced CP and increased Thr had no effect (P
> 0.05) on blood parameters and liver enzymes activity. Based on these
findings, it can be concluded that lowering CP by 1% and increasing Thr by 10%
resulted in better growth performance, breast yield and economics efficiency
than lowering CP by 2% and increasing Thr by 20%. © 2022 Friends Science
Publishers
Chicken meat is a good source of protein, but it also
contains vitamins and minerals such as vitamin B. It prevents cataracts and is
also used to boost immunity, reduce fatigue, regulate digestion, and strengthen
the nervous system. Various breeding programmes and researchers' studies on the
genetics of modern broilers can account for this increase in bird body weight
gain. Furthermore, high-quality feed formulation and strategies were the
primary reasons for raising poultry farming throughout the process (Sadeghi and Tabiedian 2005). In previous
years, broiler strains lacked the potential for rapid growth that modern
strains have. Factors involved in this type of productivity in poultry farming
include high dietary crude protein and amino acid concentrations in their feed (Esonu et al.
2006). The higher cost of feedstuff and excretion of nitrogen into the
environment is the main concern for nutritionists facing poultry farming. Feed
cost is the major hurdle in farming, it required about 65–70% of the total
cost. Protein covers 15% of total feed cost (Aggrey
et al. 2010).
Crude protein (CP) is a vital component of diet presents
in high levels as well most costly ingredient. The amount of CP decides the
nitrogen excretion by a bird in environment. Corn or sorghum in cereal grains
are used for energy purpose and these ingredients have low CP. Further, high
price of soybean and canola meal (high CP) limit their use in broilers diet. Recent
researches on feed efficiency introduced synthetic amino acids, which may
reduce protein usage in a diet regarding the feed and cost. Essential amino
acids are those that body cannot synthesis itself and should take from outside
sources to fulfill the body requirements (Quadros
et al. 2009). Broiler’s body
cannot synthesize Thr, so, it is considered as the third limiting amino acid
after lysine and methionine. Addition of Thr in diet had the same effect on the
bird’s growth as a diet offered with high crude protein (Abdaljaleel et al. 2019).
Among other amino acids, threonine functions as the growth of birds as well
used as precursors of L-lysine and serine in the body. It is also used in the
synthesis of many proteins that promote gastrointestinal mucus production
activity and performed its role in immune responses of broilers. Excessive or
imbalanced amount of protein is used to increase the dietary requirement of
threonine, which used as a precursor for glycine in uric acid formation (Zhang and Kim 2014). Broilers demand glycine
or serine for proper body functioning (Kheiri
and Alibeyghi 2017). Threonine metabolism is classified as amino acid
metabolism, and it consists of several steps, including protein synthesis and
degradation, nitrogen excretion in the form of uric acid in an amino acid
corporation and amino acid conversion into fat, energy, glucose, protein, CO2
and water. It is also involved in the formation of non-protein derivatives (Baker et al.
2002). Protein synthesis required the addition of limiting amino acid
Thr so alternatively; Thr catabolism covers and participates in many other
metabolism processes like (glycine, acetyl CO enzyme –A and pyruvate). Use of
limiting amino acids in low protein broilers diet may improve the growth
performance and biochemical Parameters. Therefore, the purpose of this research
was to evaluate the effects of super dosing of threonine in low protein diet on
the growth performance (body weight gain, feed intake, feed conversion ratio,
carcass yield), biochemical parameters (total cholesterol, total protein, blood
glucose triglycerides, VLDL, HDL and LDL) and for liver enzyme activity (ALT,
AST and ALP) and economics efficiency.
Trial location
The experimental trial was conducted at R&D house at
Institute of Animal and Dairy Sciences, University of Agriculture, Faisalabad.
The research trial continued for 35 days.
Shed management
The brooder was started in the house 24 h before the
arrival of chicks to make sure that the temperature in the brooding area was
uniform. Immediately after arrival, the chicks were examined for their physical
health and were put in the brooding area. The birds were reared in standard
management conditions like floor space, light, ventilation, temperature and
humidity. On
the daily basis, all drinkers and feeders were washed to avoid contamination
and fungus. A matte with limestone powder was used at the entrance of the shed
throughout the research trial.
Vaccination schedule
All the experimental birds were treated with vaccination
against Newcastle disease + infectious bronchitis at day 3, infectious bursal
disease at day 13 and 20 and Newcastle disease at day 25.
Experimental birds
One hundred and fifty-day-old broiler chicks (Hubbard’s)
were divided into three treatments including T1 (control group), T2
(CP 1% less and Thr 10% extra) and T3 (CP 2% less and Thr 20% extra)
(Table 1). Iso-caloric diets were formulated according to two phases as a
starter (1–21 days) and finisher (22–35 days) (Table 2 and 3). Treatments were
replicated into 5 subgroups having 10 chicks in each. After the arrival of
chicks were facilitated with sugar solution (1 kg sugar/5L) for flushing
purpose. On day 1st temperature was kept at 95°F and further reduced
at 5°F within every week until the 75oF. Feed and water were
provided ad labium 24 h.
Data recording
Growth performance: On arrival, broiler chickens
were weighed using a digital weighing balance which uses as an initial weight
for the starter phase. On day 22nd, all birds within a pen were
weighed again, which use as an initial weight for finisher phase. Body weight
of broilers was recorded at the end of each consequent week. Weekly BWG was calculated from the
data on body weight of birds. Data were recorded on feed intake and BWG for the
determination of birds’ efficiency of each replicate on weekly basis. It was
calculated as follows:
Feed Intake (g/bird) = [Feed offered (g)-Feed Refusal
(g)]/no. of birds
“FCR = Feed Intake (g)/Weight gain (g)”
Carcass characteristics:
At the end of the experiment, two birds/pen were randomly selected.
Birds were weighed individually and processed to get data on carcass response.
After processing feathers detached, evisceration was done in order to obtain
carcass weight including internal organs (liver, heart, spleen and gizzard),
breast meat weight and thigh meat weight and abdominal fat of the birds were
calculated through this relationship:
“Dressing percentage = Carcass weight (g)/Live weight (g)
× 100”
“Breast meat yield = Breast meat weight (g)/Live weight
(g) × 100”
“Thigh meat yield = Thigh meat weight (g)/Live weight (g)
× 100”
“Relative Organs weight = Organ Weight (g)/Live weight
(g)× 100”
Biochemical parameters:
At the end of the experimental trail, two birds/pen was selected for
blood sampling. Blood sampling was done from selected broiler chickens for
evaluation of blood glucose and total protein, liver enzyme activity (ALT, AST
and ALP) and serum biochemistry parameters (triglycerides, cholesterol, HDL,
LDL and VLDL) (Shoaib et al. 2021).
Economics
Cost of production per live weight was recorded on the
basis of feed cost and live bird weight.
Table 1: Experimental
treatments
Treatments |
Starter Phase (1-21 days) |
Finisher Phase (22-35 days) |
T1 |
CP 21.5% Thr normal |
CP 20% Thr normal |
T2 |
CP 1% less (20.5%) + Thr 10% |
CP 1% less (19%) + Thr 10% |
T3 |
CP 2% less (19.5%) + Thr 20% |
CP 2% less (18%) + Thr 20% |
Table 2: Ingredients
composition of experimental diets
Ingredients |
Starter Diet |
Finisher Diet |
|||||
T1 |
T2 |
T3 |
T1 |
T2 |
T3 |
||
Maize grain |
53.00 |
53.65 |
55.10 |
56.15 |
56.07 |
56.01 |
|
Rice tips |
2.00 |
3.00 |
3.00 |
6.10 |
6.85 |
8.70 |
|
Rice
polishing |
2.00 |
2.00 |
2.00 |
2.00 |
2.00 |
2.00 |
|
Soybean
meal 44% |
27.60 |
27.60 |
27.60 |
23.20 |
23.20 |
23.00 |
|
Fish Meal |
4.00 |
2.50 |
1.00 |
2.40 |
1.20 |
0.55 |
|
Poultry
by-product meal |
2.50 |
1.70 |
0.90 |
3.00 |
1.90 |
0.55 |
|
Canola meal |
0.91 |
0.91 |
0.91 |
0 |
0 |
0 |
|
Molasses |
2.00 |
2.00 |
2.50 |
1.50 |
2.50 |
2.50 |
|
Oil |
3.00 |
3.00 |
3.00 |
3.00 |
3.00 |
3.00 |
|
Lime stone |
0.50 |
0.50 |
0.50 |
0.50 |
0.50 |
0.50 |
|
DCP |
1.50 |
1.90 |
2.00 |
1.40 |
1.80 |
1.90 |
|
L-Lysine
sulphate, 55% |
0.55 |
0.67 |
0.79 |
0.38 |
0.50 |
0.61 |
|
DL-Methionine,
99% |
0.20 |
0.22 |
0.24 |
0.13 |
0.15 |
0.17 |
|
L-Threonine, 98% |
0.14 |
0.25 |
0.36 |
0.14 |
0.23 |
0.41 |
|
Nutrimin* |
0.05 |
0.05 |
0.05 |
0.05 |
0.05 |
0.05 |
|
Vitalink** |
0.05 |
0.05 |
0.05 |
0.05 |
0.05 |
0.05 |
|
Total |
100.00 |
100.00 |
100.00 |
100.00 |
100.00 |
100.00 |
|
“Each kg of Vitalin*
supplied: vitamin A 20000 KIU; vitamin D3 5400 KIU; vitamin E 48000
mg; vitamin K3 4000 mg; vitamin B1 4000 mg; vitamin B2
9000 mg; vitamin B6 7600 mg; vitamin B12 20 mg; niacin
60000 mg; pantothenic acid 20000 mg; folic acid 1600 mg; biotin 200 mg
Each Kg of Nutrimin**
supplied: Iron 10000 mg; zinc 120000 mg; manganese 140000 mg; copper 12000 mg;
iodine 1800 mg; cobalt 400 mg and selenium 360 mg”
Table 3: Nutrients
composition of experimental diets
Nutrients |
Starter Diet |
Finisher Diet |
|||||
T1 |
T2 |
T3 |
T1 |
T2 |
T3 |
||
Crude protein |
21.5 |
20.5 |
19.5 |
20.00 |
19.00 |
18.00 |
|
ME (kcal/kg) |
3030 |
3030 |
3030 |
3100 |
3100 |
3100 |
|
Ether extract |
6.32 |
6.12 |
5.94 |
6.36 |
6.12 |
5.89 |
|
Crude fiber |
3.27 |
3.08 |
2.91 |
3.11 |
2.86 |
2.52 |
|
Ash |
3.53 |
3.10 |
2.71 |
3.00 |
2.66 |
2.32 |
|
Dig. Lysine |
1.28 |
1.28 |
1.28 |
1.05 |
1.05 |
1.05 |
|
Dig.
Methionine |
0.51 |
0.51 |
0.51 |
0.41 |
0.41 |
0.41 |
|
Dig. Threonine |
0.81 |
0.89 |
0.97 |
0.72 |
0.79 |
0.95 |
|
Calcium |
0.99 |
0.97 |
0.88 |
0.88 |
0.87 |
0.80 |
|
Phosphorus, available |
0.46 |
0.45 |
0.40 |
0.40 |
0.39 |
0.35 |
|
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
Statistical analysis
Data collected for each treatment group was analyzed
through the Analysis of Variance technique under Completely Randomized Design
and comparison of means were made by Tukey’s test (Steel et al. 1997).
Growth performance
Feed intake: During
starter phase, feed intake was higher (P <
0.05) in birds of T1 (Control) treatment while it was lower (P < 0.05) in birds of T2 treatment
(1% less CP + 10% higher Thr). During finisher phase, it was not similar (P > 0.05) in all treatments. Overall,
lower (P < 0.05) feed intake was
recorded in birds of treatment T2 (1% less CP + 10% higher Thr) than other
treatments (Table 4).
Body weight gain:
During starter phase, body weight gain was higher (P < 0.05) in birds of treatment T1 and T2 (1% less CP + 10%
higher Thr), while lower (P < 0.05)
weight gain was recorded in birds of treatment T3 (2% less CP + 20% higher
Thr). During finisher phase, weight gain was higher (P < 0.05) in birds of treatment T1 (control) than others.
Overall, higher (P < 0.05) body
weight gain was recorded in birds of treatment T1 and T2 (1% less CP + 10%
higher Thr), and lower (P < 0.05)
body weight was seen in birds of treatment T3 (2% less CP + 20% higher Thr) (Table
5).
Feed conversion
ratio: Improved (P < 0.05) FCR
was recorded in birds of treatment T1 and T2 (1% less CP + 10% higher Thr) and
poor (P < 0.05) FCR was observed
in birds of treatment T3 (2% less CP + 20% higher Thr) during starter, finisher
and overall period (Table 6).
Carcass characteristics
Table 4: Feed intake of broilers with diets containing various levels of CP
and threonine
Treatments |
FI (g/ bird) |
||
1–21 days |
22–35 days |
1–35 days |
|
T1 |
1248.20a |
1903.62 |
3151.82a |
T2 |
1230.44b |
1896.90 |
3127.34b |
T3 |
1244.32ab |
1905.56 |
3149.88a |
SEM |
4.34 |
6.68 |
5.15 |
P-value |
0.032 |
0.640 |
0.010 |
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
P > 0.05 (non-significant), P
< 0.05 (significant)
Table 5: Weight gain
of broilers reared on diets containing various levels of CP and threonine
Treatments |
WG (g/ bird) |
||
1–21 days |
22–35 days |
1–35 days |
|
T1 |
839.54a |
1029.24a |
1868.78a |
T2 |
836.56a |
1025.70ab |
1862.26a |
T3 |
803.71b |
1014.59b |
1818.30b |
SEM |
2.97 |
3.12 |
2.97 |
P-value |
0.0001 |
0.016 |
0.0001 |
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
P > 0.05
(non-significant), P < 0.05
(significant)
Table 6: Feed
conversion ratio of broilers reared on diets containing various levels of CP
and threonine
Treatments |
Feed conversion ratio |
||
1–21 days |
22–35 days |
1–35 days |
|
T1 |
1.49b |
1.85b |
1.69b |
T2 |
1.47b |
1.85b |
1.68b |
T3 |
1.55a |
1.88a |
1.73a |
SEM |
0.006 |
0.007 |
0.004 |
P |
0.0001 |
0.016 |
0.0001 |
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
P > 0.05
(non-significant), P < 0.05
(significant)
Dressing
percentage and chest yield were higher (P < 0.05) in birds of treatment T1 (control) and they were lower (P < 0.05) in treatment T3 (2% less CP + 20% higher thr). Leg, heart, gizzard, liver, spleen and abdominal fat
percentage were not affected (P > 0.05) by increasing level of threonine in low protein broilers
diet (Table 7).
Biochemical parameters
At the end of experimental trail, two birds/pen was
selected for blood sampling. Blood parameters (glucose and total protein),
liver enzyme activity (ALT, AST and ALP) and serum biochemistry parameters (triglycerides,
cholesterol, HDL, LDL and VLDL) were not affected by increasing level of threonine in low protein broilers
diet (Table 8).
Economics efficiency
Cost of production per live weight was lower in birds of
T2 (1% less CP + 10% higher Thr) and it was higher in T3 (2% less CP + 20%
higher Thr) (Table 9).
Super dosing of Thr (10 and 20%) with low protein (1 to
2%) had increased feed intake in broilers. This might be due to that Thr
improve the gut health and reduce passage rate resulting in increased feed
intake. These results of feed intake were in agreement with Mejia et al.
(2012) who reported that feed intake was higher when birds fed a diet
containing 0.77% threonine during the experimental period day (35–49). Nasr and Kheiri (2011) demonstrated that chicks
fed on a diet containing 1.2% Thr had higher feed intake during the overall
period day (0–42). Panda et al. (2011) reported that feed intake was increased with
an elevated level of Thr up to 1.2% during the starter phase day (1–21). Zaghari et al.
(2011) demonstrated that threonine at 0.8 and 0.9% had higher feed
intake than other dietary treatments during the starter phase day (1–21). Sterling et al.
(2003) recorded results in an increase in feed intake of broilers fed
diets with increasing Thr at day (9–18). Results are not in line with the
findings of Ahmad et al. (2020) who reported that 110 and 120% Thr had lower
feed intake. Wijtten et al. (2004) concluded that different levels of Thr (0.92,
1.04, 1.17, 1.32 and 1.43%) had no effect on feed intake during the finisher
phase day (14–34) in commercial broilers. Vieira
et al. (2004) concluded that
feed intake was similar in birds fed different ratios of Thr and methionine
days (14–35).
Super dosing of Thr (10 and 20%) extra with low protein
(1 and 2%) less had increased weight gain of broilers. This is because Thr
improve the gut health and villus surface area resulting in improved nutrient
absorption and body weight gain. The results are similar with Ahmad et al.
(2020) who reported
that Thr (10 and 20%) resulted in a greater growth performance than the control
group. Ishii et al.
(2019) observed that addition on lysine + Thr in broilers diet had increased
body weight gain than control diet. Zarrin- Kavyani et al. (2018) reported that
addition of 110% Thr in broilers diet had higher weight gain than 100 and 120%
during grower phase. Wils-Plotz et al. (2013) observed that feed
intake and weight gain were significantly increased at 0.54% threonine
supplementation in those birds, which were not facilitated to that fed 0.17%
threonine. The broilers gained 127.8 and 95.4 g more weight at an equal level
of feed intake at pre- and post-inoculation. Rezaeipour
et al. (2012) concluded that
the highest FCR and weight gain were found at 7.6 g/kg in birds. Similar
results were also obtained by Wijtten et al. (2004) observed that BWG was increased in birds fed a high level of
threonine (1.45%) during the trial (day 14–34th) in commercial
broilers. In contrast, Helal et al. (2020) reported that different levels of Thr (100, 150 and 200%)
had no effect on body weight gain.
Table 7: Carcass
characteristics of broilers reared on diets containing various levels of CP and
threonine
Treatments |
Carcass characteristics (%) |
|||||||
Dressing |
Chest |
Leg |
Relative heart |
Relative gizzard |
Relative liver |
Relative
spleen |
Relative abdominal
fat |
|
T1 |
60.39a |
26.39a |
22.15 |
0.52 |
1.12 |
2.42 |
0.16 |
2.17 |
T2 |
60.37ab |
26.06ab |
21.73 |
0.53 |
1.15 |
2.56 |
0.16 |
2.19 |
T3 |
58.97b |
25.19b |
21.74 |
0.52 |
1.15 |
2.44 |
0.17 |
2.24 |
SEM |
0.376 |
0.246 |
0.204 |
0.0310 |
0.038 |
0.079 |
0.006 |
0.029 |
P |
0.032 |
0.013 |
0.289 |
0.942 |
0.809 |
0.443 |
0.515 |
0.240 |
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
P > 0.05
(non-significant), P < 0.05
(significant)
Table 8: Blood
parameters of broilers reared with diets containing various levels of CP and
threonine
Treatments |
Blood Parameters |
Serum biochemistry parameters |
Liver enzyme activity |
|||||||
Sugar (mg/dL) |
Total Protein (g/dL) |
Triglycerides (mg/dL) |
Cholesterol (mg/dL) |
HDL (mg/dL) |
LDL (mg/dL) |
VLDL (mg/dL) |
ALT (IU/L) |
AST (IU/L) |
ALP (IU/L) |
|
T1 |
290.80 |
4.65 |
99.55 |
129.28 |
75.76 |
39.44 |
22.08 |
4.498 |
165.74 |
223.00 |
T2 |
302.52 |
4.58 |
106.45 |
126.05 |
81.59 |
39.06 |
21.19 |
4.448 |
163.35 |
229.70 |
T3 |
307.74 |
4.52 |
108.19 |
129.08 |
80.92 |
38.47 |
22.15 |
4.434 |
162.39 |
249.50 |
SEM |
8.17 |
0.05 |
6.86 |
6.47 |
4.54 |
4.16 |
1.41 |
0.14 |
2.26 |
13.90 |
P |
0.356 |
0.176 |
0.652 |
0.925 |
0.622 |
0.986 |
0.868 |
0.944 |
0.575 |
0.403 |
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
P > 0.05
(non-significant), P < 0.05
(significant)
Table 9: Economics of
broilers reared with diets containing various levels of CP and threonine
Treatments |
Day old bird
cost |
Total feed
cost (per bird) |
Miscellaneous |
Production
cost/bird |
Av. body
weight (g) |
Production
cost (per kg) |
T1 |
25 |
187.55a |
20 |
232.55a |
1913.86a |
121.51b |
T2 |
25 |
184.73b |
20 |
229.73b |
1907.18a |
120.46c |
T3 |
25 |
184.93b |
20 |
229.93b |
1863.64b |
123.38a |
SEM |
- |
0.297 |
- |
0.297 |
2.98 |
0.22 |
P |
- |
0.0001 |
- |
0.0001 |
0.0001 |
0.0001 |
T1 = (Control group)
T2 = (1% less CP and 10% higher threonine)
T3 = (2% less CP and 20% higher threonine)
P > 0.05
(non-significant), P < 0.05
(significant)
Super dosing of
Thr (10%) extra with low protein (1%) less had improved FCR. Improved FCR in
10% higher Thr may be associated with improved nitrogen retention. Results are
similar with the findings of Ahmad et al. (2020) who reported that
110 and 120% Thr had improved FCR. Rasheed et al. (2018) reported that birds
fed diet containing 10% higher Thr had improved FCR than control and 20% higher
Thr. Zarrin-Kavyani et al. (2018) reported that addition of 110% Thr in broilers
diet had improved FCR than 100 and 120% during starter phase. Ishii et al.
(2019) observed that addition on lysine + Thr in broilers diet had
improved FCR than control diet. Dozier et al. (2008) used different Thr
levels (0.53, 0.63 and 0.73%) from 42 to 56 days. Highest weight gain and
better FCR was recorded in broilers at 0.73 and 0.63% threonine, respectively.
Results are not in line with Helal et al. (2020) who reported that
different levels of Thr (100, 150 and 200%) had no effect on FCR. Zaghari et al.
(2011) who concluded that the lower FCR ratio was recorded at 0.74%
threonine level in the diet. Ayasan et al. (2009) demonstrated that
at 0.86% Thr level lower the FCR in broilers during the finisher phase (22–42).
Dressing percentage and breast yield of broilers were
higher in broilers of group T1 (control) and it was lower in group T3. This
might be due to that Thr addition increased the abdominal fat resulting in
reduced breast yield. Super dosing of Thr (10 and 20%) with low protein (1 and
2%) had no effects on thigh meat, liver, heart, spleen, gizzard weight and
abdominal fat of broilers. Results obtained for carcass yield are agreed with Helal et al.
(2020) who observed that Thr at 100% had higher dressing percentage,
while relative organs weight were not affected by different Thr levels. Nasr and Kheiri (2011) concluded that birds fed a diet
containing 1.3 percent Thr had higher carcass weight and lower fat deposition
in broilers over the course of a day (0–42). Ghahri
et al. (2010) discovered that
birds fed three different levels of Thr (0.9, 0.10 and 1.1 percent) had a
significant dressing percentage, breast, and thigh yield (21–42). The results
contradict the findings of Chen et al. (2017) who found that
adding Thr at 1 g/kg improved spleen weight and Thr at 3 g/kg improved thymus
weight.
Blood parameters (glucose and total protein), liver
enzyme activity (ALT, AST and ALP) and serum biochemistry parameters
(triglycerides, cholesterol, HDL, LDL and VLDL) were not affected by increasing level of threonine in low protein broilers
diet. This might due to variation is data leads to non-significant results.
Results are in line with the findings of Mehdipour
et al. (2020) who showed that
different levels of Thr had no effect on blood hematology parameters. Helal et al.
(2020) reported that different levels of Thr (100, 150 and 200%) had no
effect on albumin and triglycerides concentration. These results were not
supported by widely published work of Al-Hayani
(2017) experimented to check the effects of graded levels of threonine
(Thr, 300, 600 and 900 mg/kg) on blood parameters in broilers. The
concentration of Thr 900 mg/kg showed a significant increase on (ALT, AST,
ALP) and on total glucose levels as well.
Conclusion
Based on these findings, it can be concluded that
lowering CP by 1% and increasing threonine by 10% improved growth performance,
breast yield and economics efficiency than lowering CP by 2% and increasing
threonine by 20% without any negative effect of liver enzyme activity and
biochemical parameters.
Acknowledgments
The authors acknowledge Dr.
Mahboob Ali Hamid, Assistant Professor, Institute of Animal and Dairy Science,
University of Agriculture, Faisalabad for English grammar corrections and for
improving the overall presentation of results
Author Contribution
FW, AJ and MAJ did experimental
work and manuscript writing; MS and AM performed data
analysis; KR and NR designed the experiment; MS and FM prepared the manuscript
Conflict of
Interest
The authors declare
no conflict of interest
Data
Availability
Data is available
Ethical
Approval
All procedures performed in studies were
in accordance with the ethical committee of University of Agriculture,
Faisalabad, Pakistan
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