Abstract: One hundred and fifty broilers (1-day-old) were randomly allocated to 4 treatments, each of which had individual pens of 50 chicks and were used to investigate the effects of humic acid (HA) Saccharomyces cerevisiae (SC extract (YE), 2x108 cfu g-1) on growth performance and immunity. All animals received the same basal diet based on corn and soybean meal and while HA was added to the basal diet at 0.25% and YE 0.25%, respectively. The following diet treatments were applied: (1) Basal diet + 0 additives, (2) Basal diet 0.25% HA kg of feed (3) Basal diet 0.25% YE kg of feed (4) Basal diet 0.25% HA+0.25% YE kg of feed. Each experimental group was fed ad libitum with its own diet for 42 days. During the experiment the chicks were reared at conventional ambient temperature (from 30°C reducing to 21°C by 3°C/week) and relative humidity of 60-70%. Light was provided 24 h in a day. Performance data of each replicate was determined weekly during the experiment. All chicks were slaughtered when end of 6 weeks. Blood samples from 30 birds in each group was collected by branchial vein and were analyzed for serum biochemical values, enzyme activities and performance characteristics were measured. Body weight, body weight gain, feed intake and carcass weight were positively influenced (p < 0.05) by HA supplementation (0.25%) during the experiment. Difference among the groups in terms of gizzard, liver and biochemical parameters such as WBC, Heterophil, Lymphocyte, Monocyte, RBC, HCT were not statistically important among different treatment groups (p < 0.05). But, Glucose and BUN levels were significantly decreased in groups HA and YE (p < 0.05). ALP, ALT, Fe, Ca, P were not statistically significant among groups.
INTRODUCTION
In poultry, novel methods to improve efficiency of meat production must be developed because of antibiotic use decreases. Hence, any improvements which will serve as a replacement for antibiotics in animal feed, must enhance growth, improve feed efficiency, or decrease mortality at no additional cost to the consumer. Several ways have been suggested as strategies to limit the antibiotic usage. Addition of prebiotics, probiotics and some organic acids (Chaveerach et al., 2004). Nowadays in poultry production organic acids and live yeasts have mainly been using in order to improve animal performance (Çelik et al., 2003; Denli et al., 2003; Ricke, 2003; Madrigal et al., 1993). Besides organic acids are metabolic intermediates produced in pathways of central energy production, detoxification, neurotransmitter breakdown, or intestinal microbial activity as well. Humic Acid (HA) have been used for feed preservation, protecting feed from microbial and fungal destruction or to increase the preservation effect of fermented feed (Maslinski et al., 1993). HA are naturally occurring decomposed organic constituents of soil and lignite that are complex mixtures of polyaromatic and heterocyclic chemicals with multiple carboxylic acid side chains (Klocking, 1994; Mac Carthy, 2001). The objective of dietary acidification is the inhibition of intestinal bacteria competing with the host for available nutrients and a reduction of possibly toxic bacterial metabolites, e.g., ammonia and amines, thus improving weight gain of the host animal. Furthermore, the growth inhibition of potential pathogen bacteria and zoonotic bacteria, e.g., E. coli and Salmonella, in the feed and in the GI-tract are of benefit with respect to animal health. Humic acid has been used as an antidiarrheal, analgesic, immunostimulatory and antimicrobial agent in veterinary practices in Europe (EMEA, 1999). Similarly yeast and yeast cultures have a long standing tradition of use in animal feeds. As well known, before the widespread availability and use of synthetic vitamins, yeast was added to pet food formulations as a natural of B vitamins. Yeast culture has been shown to affect intestinal mucosa development in poultry. More recently, yeast cultures often contain supplemental enzymes which may assist in protein, carbohydrate and fat digestion. have been examined. In addition to growth performance, there are many trials showing that enrichment of diets with yeast could favorably improve the quality of edible meat from broilers. For example, edible meats from broiler chicks fed a diet containing chromium-enriched Sc exhibited increased tenderness and increased water holding capacity (Bonomi and Vassia, 1978). Sc, one of the most widely commercialized types of yeast, has long been fed to animals. Any attribute which can improve gastrointestinal tract health and immunity is extremely valuable in broiler diets. Yeast is also an excellent source of selenium and chromium, two trace minerals which may have positive effects of broiler health (Çelik et al., 2001) The objective of this study was to determine if experimental supplementation of HA, SC extract (YE) and mixture of this additives in the young broiler chicken diet may cause improve of performance and affect some serum health parameters.
MATERIALS AND METHODS
Birds and Diets
This study was conducted at Çanakkale Onsekiz Mart University
and Animal Science Department in winter of 2007. One hundred and fifty
1-day-old Ross male broiler chickens obtained from a commercial hatchery
were individually weighed, wing-banded and randomly distributed to the
different treatment groups (3 replicates of 50 chicks per dietary treatment).
Humic acid was purchased from Topkim A.Ş and was added to the diets
and mixed thoroughly in a graded sequence to specified concentrations
in the total period of experiment in the chicks were grouped based on
the following dietary treatments: 1) basal feed free additives (Control,
2) basal feed containing 0.25% HA, 3) basal feed containing 0.25% YE and
4) basal feed containing 0.25% YE+0.25% HA. The chickens were reared under
uniform management conditions with feed and water available ad libitum.
Diets were formulated for starter (0-3 week) and grower (4-6 week)
phases according to NRC specification (National Research Council, 1994)
during the experiment (Table 1). Chicks raised in floor
pens under constant light period of 24 h and individual BW, FI, FCR, BWG
mortality and morbidity of the birds were recorded at the onset of experiments
and measured weekly thereafter for each group. Feed conversion ratio was
calculated by dividing the sum of the BW of all birds in a group minus
the sum of starting BW with the weight of total feed consumed during the
entire experiment.
Collection, Processing and Analysis of Blood Samples
At the end of study (15 males and 15 females) in each treatment were
selected randomly and humanely euthanized. Blood was collected in nonheparinized
tubes by brachial vein puncture. Serum was separated and stored at -25
°C and samples were analyzed for Total Protein (TP), Blood Urea Nitrogen
(BUN), Alanine Amino Transferase (ALT), γ-Glutamyl Transferase (GGT)
and Aspartate Amino Transferase (AST) using automatic analyzer according
to the recommendation of the manufacturer with a Technicon RA-1000 system
(Miles Inc. Diagnostics Division, Tarrytown, NY) according to standard
procedures, as described by Technicon-RA Systems (1994). The differential
count was done using a Cell-Dyn blood counter and clinical chemistry with
a Corning clinical chemistry analyzer (Chiron Corporation, San Jose, CA).
Total erythrocyte count (TEC), hemoglobin (Hb), Ca, P and hematocrit were
measured using auto analyzer. Liver, kidney, gizzard, intestines were
collected, weighed and calculated as a percentage of body weight.
| Table 1: | Ingredients and nutrient composition of basal diets |
| 1Supplied kg of diet: vitamin A, 1,500 IU; cholecalciferol, 200 IU; riboflavin, 3.5 mg; vitamin E, 10 IU; pantothenic acid, 10 mg; cobalamin, 10, niacin, biotin, 0.15 mg; 30 mg; choline chloride, 1,000 mg; folic acid, 0.5 mg; thiamine 1.5 mg; pyridoxine 3.0 mg; iron, 80 mg; zinc, 40 mg; manganese, 60 mg; iodine, selenium, 0.15 mg 0.18 mg; copper, 8 mg; 2Based on National Research Council (1994) feed composition tables | |
Statistical Analysis
The data were analyzed using the General Linear Models procedure of
SAS Institute (1997). Significant differences between treatment means
were separated using the Duncan`s Multiple Range Test.
RESULTS AND DISCUSSION
HA (0.25% ) supplementation to the diet at improved (p < 0.05) BW,
BWG, FI and CW of broilers at 42 days compared with control, YE and HA+
YE groups (Table 2). The current study supports the
observations of (Yoruk et al., 2004; Kocabagli et al., 2002;
Avci et al., 2007). It is well established that the gastrointestinal
microflora (normal) plays an important role in the health and well being
of poultry. Various pathogenic microbes, such as E. coli,
have been implicated to reduce the growth of poultry. Possible mechanisms
for this reduction of growth are: toxin production, utilization of nutrients
essential to the host and suppression of microbes that synthesize vitamins
or other host growth factors. Mortality for chickens fed the control diet
was not different from that for birds fed HA and YE diets. The mortality
was also not different statistically among chickens fed HA and YE diets.
Deaths occurred toward the middle of the experiment (Table
2). Shermer et al. (2002), similarly, has been observed that
humates the inclusion of HA during later stage in broiler diet could included
in feed and water of poultry promotes growth more beneficial in respect
of performance. Besides the use of HA in animal feed, leads to an increase
in live weight of the excludes of course the possibility of antibiotic
residue or animal without increasing the amount of feed given to microbial
resistance the animal. The diet digestibility as a result of maintaining
optimum pH in the gut increases, resulting in lower levels of nitrogen
excretion and less odour in lower levels of nitrogen excretion and less
odour as calcium and trace element utilization. On the other hand, Saccharomyces
cerevisiae, one of the most widely commercialized types of yeast,
has long been fed to animals. Results of earlier studies with yeast fed
to chickens, however, have not been consistent. It has been reported by
Bonomi and Vassia (1978), Eren et al. (2000) and Onifade et
al. (1999) that feeding yeast to chicks improves BW gain and feed/gain
ratio. But Zhang et al. (2005) failed to observe a positive effect
of feeding yeast on BW of broiler chicks. Kanat and Calyalar (1996) reported
that active dry yeast effectively increases BWG without affecting feed/gain
ratio in broiler chicks in contrast. During starter period, BW, BWG, FI
and CW were not significantly (p < 0.01) affected by SE but mentioned
parameters were positively influenced (p < 0.05) by HA (0.25%) supplementation
during the experiment. Because HA stabilize the intestinal flora and thus
ensure an improved utilization of nutrients in animal feed. This leads
to an increase in live weight of the animal without increasing the amount
of feed given to the animal. Moreover, HA is effects to improve protein
digestion as well as calcium and trace element utilization. Supplementation
with yeast has also been shown to enhance survival by altering gastrointestinal
flora (Netherwood et al., 1999) to suppress growth of pathogenic
bacteria (Ehrmann et al., 2002) and by enhancing immune potency
(Balevi et al., 2001).
| Table 2: | Effects of dietary humic acid and Saccharomyces cerevisiae on broiler chickens |
| Means within row with no common superscripts differ significantly( p < 0.05) | |
In similar studies involving broilers, it was reported that supplementation
of humate (Kocabagli et al., 2002) and probiotic (Jin et al.,
1998) did not alter feed conversion efficiency on 21 day, but improved
it on 42 day. It appears that supplementation of humate and probiotic
do not improve growth by affecting FI, suggesting that improvement in
WG and reduction in FCR by supplemental humate and probiotic could be
related to their promoting effects on metabolic processes of digestion
and utilization of nutrients (Yeo and Kim, 1997; Belyavin, 1993). Findings
from this research showed that measured factors are correlated, because
as the, BW, BWG, FI and CW are improved in group HA (p < 0.05). Islam
et al. (2005) who reported that HA and YE supplementation to broiler
grower diets caused numerical improvements in feed efficiency of broilers.
This is consistent with the results from previous studies (Midilli and
Tuncer, 2001) that addition of only YE to the diet was affected carcass
compositions. Hyginus et al. (1997), Mohan et al. (1996)
and Lee et al. (2002) suggesting that (SC) affects on the performance
of laying and broiler hens compared with controls. The results of present
and previous studies as Çelik et al. (2001), Denli et
al. (2003) and Yeo and Kim (1997) agree with this report showing that
good growth performance in YE group. The results in this experiment were
similarly. Biochemical parameters such as WBC, Heterophil, Lymphocyte,
Monocyte, RBC, HCT stay on normal levels under the influence of HA and
YE in comparison with control groups and there were no differences in
blood parameters among different treatment groups (p < 0.05), (Table
3). ALP, ALT, Fe, Ca, while were not statistically significant among
groups (p < 0.05), but P was different in group HA (Table
4). There was no toxic effect of HA that was evident by the absence
of any dramatic change in relative organ weights or other telltale signs
of serum clinical chemistry that would suggest liver, muscle, or kidney
dysfunction. RBX, WBC, monocyte and HCT values were not affected, but
there was a decrease in blood heterophil counts and heterophil to lymphocyte
ratio, which was significant in 4 week HA-treated birds.
| Table 3: | Effect of HA and SC on blood differential counts of 6-week-old broiler chickens (n = 15), mean ± SEM* |
| *There were no differences in blood parameters among different treatment groups (p < 0.05) | |
| Table 4: | Effect of Humic acid and Saccharomyces cerevisiae on serum chemistry of 6-week-old chickens (n = 13), mean ± SEM |
| 1BUN: Blood Urea Nitrogen, 2ALP: Alkaline Phosphatase, 3ALT: Alanine Amino Transferase; abDissimilar scripts in a column denote significant differences p<=0.05 | |
Overall these results show that HA improved growth more than YE in broiler chicks and it does not have any adverse health effects on chickens. In conclusion, supplementation of HA (25%) and YE (25%) may extend the profitability of a broiler chicks without advers effects.
ACKNOWLEDGMENTS
This study was supported in part by BANVİT and Scientific Research Commission of COMU (BAP).