Abstract: This experiment was conducted to determine the effects of increasing, energy to protein ratio and partial decreasing of nutrient contents of diet using different levels of fats on broiler chickens performance and serum lipids. With addition of fats (Poultry oil, Soybean oil and Tallow) in two levels (4 or 8%) to basal diet that was already balanced on NRC (1994) recommendations, seven different non-isocaloric and non-isonitrogenic diets were prepared (12 or 24% increasing of energy to protein ratio in 4 or 8% of fat level addition, respectively) and given ad libitum between 22 to 49 day of age. The blood samples were collected at 35 and 49 day and weight of selected visceral organs were recorded at 49 day. The results suggested that high fat intake had no significant effect on Final Body Weight (FBW) and Feed Conversion Ratio (FCR). Numerically the FBW was higher in all groups that received high fat levels than control group. But abdominal fat deposition only in birds that was fed by additional soybean oil and tallow in 4% level was constant. The liver weight significantly decreased (p<0.01) and abdominal fat weight significantly increased (p<0.05) by elevation of fat level. Serum lipids concentrations had no significant difference in dietary treatments. Serum LDL concentration showed significant elevation from 35 to 49 day (p<0.01), whereas serum cholesterol concentration showed decline at the same times (p<0.05). With increasing of dietary fat level from 4 to 8%, serum cholesterol had showed elevation (p<0.05). Therefore, it seems that broilers are more resistant against the high dietary fat intake and they can be effectively used for nutritional and growth requirements promoting, without mortality.
INTRODUCTION
Fats have been shown to be a practical and economical means by which
to increase energy levels in poultry diets and growth stimulates (Griminger,
1986; Latour et al., 1994). The large amount accumulation of fat
in the abdominal cavity is a problem with new commercial broilers, since
modern broilers contains about 150-200 g fat kg-1 of body weight
and over 85% of it is physiologically non-essential (Sadeghi and Tabiedian,
2005). Other important roles of fats in diet are their inhibition from
de novo lipogenesis; provide varying quantities of the nutrients
such as linoleic acid, vitamins, diet palatability, mechanical and structural
roles and low heat increment (Choct et al., 2000; Leeson and Summers,
2001). Therefore, the specialists endeavor on the basis of these advantages
and defects of dietary fat intake, a functional diet to balanced (Alparslan
and Ozdogan, 2006).
Serum lipids concentrations as metabolical and physiological indicators
are affected by dietary fats levels intake. (Peebles et al., 1997).
All fats, particularly saturated animal fats usually have been used in
later phases of feeding, because of limited digestibility in young chicken
(Leeson and Summers, 2001). In this study, the relationships between high
fats intake with performance values, serum lipids concentrations and weight
of visceral organs in male broilers were determined. In the other hand,
the responses of broilers body to high energy and low protein diets in
comparison to one balanced diet on National Research Council (1994) recommendations
were examined. Then, on the basis of the obtained results in case of using
rich energy and diluted protein diets can be resolution to optimum securing
of nutritional and growth requirements and partial decreasing of feed
cost.
MATERIALS AND METHODS
This study was conducted at Islamic Azad University, Shabestar branch,
Shabestar-Iran in summer of 2006. Total of 210 one-day old broiler chicks
of the Cobb-500 strain from male sex were randomly assigned in 21 pens.
Each bird initially occupied 0.08 m2 of floor space. The pens
were randomized with respect to dietary treatment. Birds were provided
with continuous light. This experimental design was completely Randomized
design, with seven combinations treatment and three replicates. With addition
of three types of fats including poultry oil, soybean oil and tallow in
two levels (4 or 8%) to basal diet that was already balanced on National
Research Council (1994) recommendations. Seven different non-isocaloric
and non-isonitrogenic diets were prepared (12 or 24% increasing of energy
to protein ratio in 4 or 8% of additional fat level, respectively) and
given ad libitum at 22 to 49 day old (grower and finisher periods).
Total birds were fed a resembling starter diet at 1 to 21 day old. Ingredient
percentage and calculated analysis of grower and finisher diets are provided
in Table 1 and 2. At 35 and 49 day
of age in fasting state, bloods samples were randomly collected from wing
vein of one bird per pen and rapidly were centrifuged at 5000 rpm during
5 min and then sera by using commercial kits (Pars Azmun) in auto analyzer
(ALCYON 300) were analyzed.
| Table 1: | Ingredient and calculated analysis of grower diets |
| 1C: Control (basal diet); T: Tallow; S: Soybean oil; P: Poultry oil. 2Supplemented (For each kg of the diets): Vit. A, 12000 IU; D3, 2000 IU; E, 20 mg; K3, 3 mg; B2, 7 mg; B3, 12 mg; B5, 3 mg; B12, 0.03 mg; Biotin, 0.1 mg; Choline chloride, 300 mg and adequate anti oxidant. 3Supplemented (For each kg of the diets): Mn, 130 mg; Fe, 70 mg; Zn, 60 mg; Cu,12 mg; I, 1 mg; Se, 0.2 mg | |
| Table 2: | Ingredient and calculated analysis of finisher diets |
| 1C: Control (basal diet); T: Tallow; S: Soybean oil; P: Poultry oil. 2Supplemented (For each kg of the diets): Vit. A, 12000 IU; D3, 2000 IU; E, 20 mg; K3, 3 mg; B2, 7 mg; B3, 12 mg; B5, 3 mg; B12, 0.03 mg; Biotin, 0.1 mg; Choline chloride, 300 mg and adequate anti oxidant. 3Supplemented (For each kg of the diets): Mn, 130 mg; Fe, 70 mg; Zn, 60 mg; Cu,12 mg; I, 1 mg; Se, 0.2 mg | |
At 49 day of age, before slaughtering the final body weight and after that, weight of selected organs including liver, gizzard, heart, proventriculus, intestine and abdominal fat weight were recorded individually and presented as a percentage of live weight. The results obtained from the experiment were analyzed by an analysis of variance using the General Linear Model (GLM) procedure of SAS (2001) and means were compared by Duncan`s Multiple Range test (Duncan, 1955).
RESULTS AND DISCUSSION
Performance Values
The effect of different types and levels of dietary fats that were
added to control diet on performance values are presented in Table
3. The abdominal fat weight (percentage of live weight) in broilers
that fed with 8% level of fats was found to be significantly (p<0.05)
higher than broilers of control group. Whereas, the abdominal fat weight
in broilers that consumed diets containing tallow or soybean oil in 4%
level were no significantly higher than control group at 49 day of age.
Visceral Organs Weight
The effect of different types and levels of dietary fats that were added
to control diet on visceral organs weight are presented in Table
4. The liver weight (percentage of live weight) was significantly
lower (p<0.01) in broilers that fed with diets containing 8% each one
of fats and 4% of soybean oil at 49 day of age. Briefly, the weight of
liver had showed decreasing by addition of fats to diet.
Serum Lipids
The effect of dietary treatments on serum lipids were no significantly
difference at 39 and 49 day of age (Table 5). Serum
LDL concentration showed significant increasing from 35 to 49 day of age
| Table 3: | Means comparison of dietary treatments effect on performance values at 49 day of age |
| a, b, c: Means within diets for each performance values with no common superscript differ significantly (p<0.05). 1C: Control (basal diet); T: Tallow; S: Soybean oil; P: Poultry oil | |
| Table 4: | Means comparison of dietary treatment effect on visceral organs weight at 49 day of age |
| a, b, c: Means within diets for each visceral organs weight with no common superscript differ significantly (p<0.01). 1C: Control (basal diet); T: Tallow; S: Soybean oil; P: Poultry oil | |
| Table 5: | Means comparison of dietary treatments effect on serum lipids at 39 and 49 day of age |
| 1C: Control (basal diet); T: Tallow; S: Soybean oil; P: Poultry oil | |
| Table 6: | Means comparison of serum lipids at 35 and 49 day of age |
| a, b: Means within day of age for each serum lipids with no common superscript differ significantly (p<0.05) | |
(p<0.05), whereas serum cholesterol and triglycerides concentrations showed decrease at same times (p<0.05) (Table 6). At 49 day of age increasing dietary fats level from 4 to 8%, serum cholesterol and triglycerides concentrations significantly were showed elevation (p<0.05), whereas serum HDL concentration had showed significantly decreasing by increasing of fats level at 35 day of age (p<0.05).
Performance Values
The observations obviously indicates with addition of fats to control
diet that was balanced on NRC recommendations, the abdominal fat weight
due to increasing of energy to protein ratio and stimulating of lipogenesis
was significantly elevation (p<0.01). Bartov (1987) found that diets
with a wide E: P ratio fed 1 or 2 to 7 weeks consistently and significantly
increased abdominal fat pad size at 7 week of age. Keren et al.
(1990) were reported that the relative weight of adipose tissue was higher
in birds that fed high fat diet. But, Tabiedian et al. (2005) were
reported that lowest abdominal fat in groups of fed additional 0, 2.5,
5 and 7.5% soybean oil was observed in chicks that fed with a diet containing
7.5% soybean oil. Another performance values were no significant affected
by additional dietary fats, but numerically due to increasing of diet
palatability in broilers that fed with additional fat were better than
broilers of control group. There was numerically, higher feed intake and
final body weight and better feed conversation ratio in broilers that
fed with 8% additional tallow fat. Sadeghi and Tabiedian (2005) were showed
that adding of 5 and 7.5% tallow significantly (p<0.05) increasing
feed intake due to better palatability of fat supplemented diet. These
results showed that addition of fats to balanced diet and higher energy
to protein ratio could meet all requirements for better growth rate.
Visceral Organs Weight
Addition of fats to control diet due to decreasing of liver lipogenesis
activity, significantly (p<0.01) decreased liver weight (Table
4). Kirkpinar et al. (1999) were reported that liver weight
effected by dietary fats (p<0.01). Tabiedian et al. (2005) reported
that feeding different levels of soybean oil and tallow and protein had
no effected on liver weight. Feeding with diets of containing additional
fats had no effected on weight on gizzard, heart, proventriculus and intestine
at 49 day of age (Table 4). This is agreement with results
of Maiorka et al. (2005) and Sadeghi and Tabiedian (2005). Whereas,
Kirkpinar et al. (1999) were reported that weight of liver, gizzard
and heart were effected by dietary fats (p<0.01). Numerically, the
weight of gizzard in broilers that fed with additional fat in diet, probably
due to lubricating of diet by fat and lowering of gizzard activities had
showed decreasing at final of experiment (49 day).
Serum Lipids
The effect of dietary treatment on serum lipids had no significant
different (Table 5). Numerically, broiler chicken that
receive additional fat have been found to have lower cholesterol concentration
than birds fed control diet at 39 and 49 day of age. Resistance to high
fat intake can also be increased by stimulation of cholesterol catabolism
(Subbiah et al., 1983). Peebles et al. (1997) were reported
that the 7% fat had a depressing effect on cholesterol in comparison to
the 3% fat in diet. Alparslan and Ozdogan (2006) have confirmed that with
addition of fish oil to diet, cholesterol values numerically had showed
decrease in all groups. Because, cholesterol down-regulation the LDL receptor
and inhibit the removal of LDL from serum by liver, the concentration
of LDL similar to cholesterol concentration in control group numerically
was higher than broilers that fed with additional fats in experimental
diets. Therefore higher cholesterol, triglycerides and LDL concentration
do not necessarily occur in broilers that fed with high-fat diet and they
may be more efficient in clearing the added fat from their systems. This
more resistance against the high dietary fat intake, may by due to an
over-compensation may be related to the down-regulation of lipoprotein
lipase. Concentrations of serum cholesterol and triglycerides significantly
(p<0.05) and HDL numerically had showed decline from 35 to 49 day of
age, but serum LDL concentration showed significant elevation at the same
times (p<0.05) (Table 6). The relationship between
cholesterol and HDL are largely related to the fact the HDL particles,
rather than LDL, are the main cholesterol carriers in broiler chickens
(Hermier and Dillon, 1992). These results are in agreement with previous
studies (Castillo et al., 1992; Peebles et al., 1997). The
results of Table 7 show that elevation of fats from
4 to 8% had no significant effect on serum cholesterol and triglycerides
at 35 day of age.
| Table 7: | Means comparison of additional fat levels effect on serum lipids at 39 and 49 day of age |
| a, b: Means within additional fat percentage for each serum lipids with no common superscript differ significantly (p<0.05) | |
But, at 49 day of age the body system of broilers do not resistance
against the high fat level (8%) and serum cholesterol and triglycerides
concentrations in broilers that fed with 8% additional fat significantly
were higher than broilers fed with 4% additional fats (p<0.05). Peebles
et al. (1997) had showed that the serum cholesterol was lower in
broilers that fed 7% additional fat than is 0 and 3% additional fat at
35 day of age. Furthermore, they showed triglycerides concentration was
also higher in birds that fed with diets containing of 3% additional fat
compared to the 7% at 21 day of age.
It seems probable that the 8% level of fat due to existence of pathophysiologic
state in broilers body systems, significantly cause decline serum HDL
concentration at 35 day of age (p<0.05). But, this state probably due
to adaptation of broilers system to high fat intake becomes dismissed
at 49 day of age. With increasing of fat level from 4 to 8%, the serum
LDL concentration numerically had showed elevation at 35 and 49 day of
age. Griffin and Whitehead (1982) were reported that LDL concentration
was only slightly higher in broilers fed on the high fat diet at 3 and
7 weeks of age.
CONCLUSION
Broiler chickens probably because of some physiological resistance systems, like over-compensation (down-regulation of lipoprotein lipase) are more resistant against the high fat intake. Addition of 4% soybean oil or tallow to basal diet that was already balanced on NRC recommendations (increasing of energy and lowing of protein) is benefit for broilers performance, without significant increasing of abdominal fat weight, mortality and disorder in serum lipids. Certainly, with increasing of fat level from 4 to 8% and continuous from 35 to 49 day of age, health state in some serum lipids showed paucity disordering.
ACKNOWLEDGMENTS
This article was summarized from the master thesis project of Tohid Vahdatpour who at present is Ph.D student of veterinary physiology. The authors are grateful to all staff of Islamic Azad University, Shabestar branch, Shabestar-Iran.