The Effect of Humic Substances on the Meat Quality in the Fattening of Farm Pheasants (Phasianus colchicus)

Abstract

Background: The effects of humic substances (HSs) on the carcass characteristics and meat quality traits of breast and thigh muscles were studied. Methods: In total, 200 pheasants were allocated to 4 treatments, each containing 50 birds. The control birds were fed a diet without additives (0% HS); the other treatment birds were fed diets containing HSs at 0.5, 0.75 and 1.0% from 1 to 90 days of age. At the end of the experiment, several carcass characteristics were measured and breast and thigh muscle samples were taken to determine the composition of several nutrients by standard laboratory methods and procedures. Results: The carcass weights of both males and females increased significantly (p < 0.05) in the 0.50 HS and 0.75 HS groups after supplementation with HSs. The same effect of humic substances in the 0.50 and 0.75 HS groups was found in the weight of breast and thighs (p < 0.05). Significantly (p < 0.05), the highest carcass yield in males and females was found in the 0.50 HS group. Conclusions: Feeding with a diet containing HSs can have a beneficial influence on the carcass parameters, decrease the crude fat content in the meat and change the profile of bioactive fatty acids in the breast and thigh muscles of broiler pheasants.

1. Introduction

Pheasant meat (Phasianus colchicus) production can be ensured by two sources: hunting and farming [1,2]. Due to the growing interest in healthy animal products, markets demand pheasant meat for its high nutritional value, high-quality protein content and low fat content [3,4].

Humates or humic substances (HSs) are natural substances that have been used in agriculture for many years for their positive impact and nutritional benefits for domestic animals. The active components of HSs contain humic acid (HA), humus, ulmic acid, fulvic acid, humin and other microelements, with the potential to stimulate growth by improving the uptake of micronutrients [5,6,7]. Humic substances are characterized by their immunostimulant, anti-inflammatory and antiviral properties thanks to their ability to form a protective film on the mucous epithelium of the intestine against infections and toxins [8].

Humic acids (HAs) are natural organic compounds that are formed as a result of the chemical and biological decomposition of organic matter and the synthetic activity of microorganisms. At present, HAs are used mainly in agriculture, industry, environmental protection and medicine [9,10,11,12,13,14].

During recent years, the addition of HA at a determined amount in feed mixtures or drinking water has been shown to improve the performance of poultry [15]. For this reason, HAs are widely used in the position of an alternative growth stimulator for antibiotics [16,17,18,19,20]. A few works have investigated the effect of the addition of HAs as a growth stimulator in poultry nutrition and obtained positive results [21,22,23].

Several authors have reported the effect of HSs on poultry meat production [24,25,26,27]. Semjon et al. [25] and Jaďuttová [26] compared the effect of 0.8 and 1.0% additions of natural HSs to feed mixture pellets on the meat quality of broilers. Ozturk et al. [28] and Ozturk et al. [29] noted a positive effect of HSs on the carcass characteristics and meat quality. The addition of HSs to broiler diets and the effect on growth, carcass yield and meat quality has been monitored by Nagaraju et al. [30] and Ozturk et al. [31].

It has been shown that, despite their common properties, there are differences in HA effects resulting from the nature of the original substance and the method of isolation. However, these effects of HSs may be variable because of differences in the inclusion level and form (water or feed mixture), in the characteristics (e.g., chain length and composition or hydrophobicity) and in the origin (e.g., plant, soil, peat or coal) of organic acids, including humic acid and/or the digestibility of the diet used [28,29,31,32,33].

In Slovakia, the consumption of pheasant meat is ensured only by hunting pheasants. Therefore, the aim of our study was oriented to analyze the effect of HSs, including HA, on the carcass parameters and nutritional value of pheasant meat that had been fattened up to 90 days of age. The research hypothesis was that the addition of humic acid to the feed mixture would have the ability to influence the meat quality of pheasants.

2. Materials and Methods

2.1. Animals and Housing

Broiler pheasants were housed in pens on deep litter. Each group was housed separately with the same microclimatic conditions until the age of 42 days. In the following period, the birds were acclimatized and placed in outdoor, partially covered aviaries. During the experiment, the broiler pheasants were healthy with excellent body conditions. The conditions of animal care and manipulations were realized by workers with essential experience and the use corresponded with the instructions of the Ethics Committee of the Slovak University of Agriculture in Nitra (Protocol No. 48/2013).

2.2. Feeding

In total, 200 1-day-old pheasants were housed in 4 groups of 50 per pen (1 group consisted of 10 pieces with 5 replications) and assigned to 4 treatments: 1 = basal diet without humic acids; 2 = basal diet with 0.50% humic acids in the feed mixture; 3 = basal diet with 0.75% humic acids in the feed mixture; and 4 = basal diet with 1.00% humic acids in the feed mixture. Humic acids in a powder form were added to the total feed mixture during the manufacturing. The experiment lasted 90 days.

The broiler pheasants in all groups were fed standard fattening complete feed mixtures: a starter from day 1 to day 35 and a grower from day 36 to day 90 of the fattening. The nutrient composition of the analyzed feed mixtures is presented in

Table 1. Nutrient composition of diet: starter.

Nutrient	Unit	Control	0.50% HS	0.75% HS	1.00% HS
Crude protein	%	29.00	28.09	28.35	28.62
Crude fat	%	1.63	1.82	1.80	1.80
Crude fiber	%	3.90	4.66	3.53	3.72
Crude ash	%	7.27	8.73	7.90	7.70
Ca	g/kg	11.88	17.93	16.23	16.94
P	g/kg	9.53	9.81	9.83	10.44
Mg	g/kg	3.48	3.66	3.47	4.22
Na	g/kg	1.61	1.99	1.83	2.77
K	g/kg	14.66	12.77	12.79	9.80
Cu	mg/kg	17.21	17.26	21.72	12.67
Fe	mg/kg	217.46	297.51	296.96	311.81
Mn	mg/kg	45.37	51.90	49.33	56.25
Zn	mg/kg	115.10	125.40	112.40	90.20

and

Table 2. Nutrient composition of diet: grower.

Nutrient	Unit	Control	0.50% HS	0.75% HS	1.00% HS
Crude protein	%	24.74	26.62	26.17	26.11
Crude fat	%	1.89	1.89	1.86	1.67
Crude fiber	%	3.25	3.49	2.91	2.85
Crude ash	%	9.62	9.40	9.06	7.86
Ca	g/kg	18.65	18.15	16.97	16.06
P	g/kg	9.65	10.05	9.92	9.52
Mg	g/kg	3.86	3.88	3.73	4.02
Na	g/kg	3.77	3.51	2.88	3.21
K	g/kg	12.98	13.15	12.92	9.12
Cu	mg/kg	17.43	17.10	18.46	13.44
Fe	mg/kg	273.41	306.39	313.26	314.64
Mn	mg/kg	53.58	56.45	51.90	53.69
Zn	mg/kg	127.90	113.30	99.60	89.70

.

The broiler pheasants in all groups had available drinking water and feed mixtures ad libitum. The birds of the experimental groups received HSs (Humac Ltd. Košice, Slovak Republic) with an 85% dry matter content; there was a minimum of 62% humic acid in the dry matter, a minimum of 48% free humic acids in the dry matter, a minimum of 9% fulvonic acids in the dry matter and a minimum of 9% minerals in the dry matter.

2.3. Slaughter and Carcass Analysis

At the end of fattening, 10 representative (with a body weight closest to the group average weight) broiler pheasants (5 males and 5 females) from each group were slaughtered after a 12 hour feed mixture withdrawal. The breast, thighs, back, wings, neck, heart, gizzard (empty gizzard), liver (without a gall bladder) and abdominal weights were separated and weighed. Subsequently, we calculated the percentages of the body parts and edible giblets to the body weight. The results obtained were used to calculate the carcass yield.

2.4. Sampling and Laboratory Analysis

The samples of muscle were manually obtained from the breast (musculus pectoralis major) and thigh (musculus biceps femoris) muscles after the slaughter of broiler pheasants at 90 days of age during dissection (10 samples per each group). The nutrient composition of the diet and meat was determined by standard laboratory methods and procedures [34]. The content of metabolizable energy was calculated according to the WPSA methodology [35].

The content of the dry matter was determined by drying the sample with the gravimetric method. The crude protein was determined by the Kjeldahl method, the crude fat was determined by extraction and the gravimetric method according to the Soxhlet principle and the crude ash was determined by a complete combustion of the sample in a muffle furnace at 530 ± 20 °C (4–6 hours). The laboratory analysis of the nutritional composition of the broiler pheasant meat was carried out in the Laboratory of Quality and Nutritive Value of Feeds at the Institute of Nutrition and Genomics at the Slovak University of Agriculture in Nitra, Slovakia.

2.5. Statistical Analysis

The differences among the pheasant groups were analyzed with a one-way analysis of variance (ANOVA) by using the statistical program JASP 0.8.6 [36]. The results were evaluated using Duncan’s multiple range test [37].

3. Results

The effect of the dietary inclusion of HSs on the carcass traits of pheasant broilers is presented in

Table 3. The effect of HSs on the carcass characteristics of pheasants.

Parameter	Sex	Control	0.50% HS	0.75% HS	1.00% HS
Initial weight (g)	Male	22.31 ± 1.89	22.46 ± 1.91	22.38 ± 1.88	22.33 ± 1.89
	Female	21.84 ± 1.86	21.88 ± 1.87	21.73 ± 1.83	21.93 ± 1.88
Final weight (g)	Male	1025.97 ± 53.58 b	1201.38 ± 56.12 a	1166.89 ± 55.18 a	1045.34 ± 54.55 b
	Female	861.87 ± 33.18 b	934.51 ± 35.77 a	926.02 ± 35.21 a	876.59 ± 33.85 b
Carcass weight (g)	Male	717.26 ± 34.68 b	841.16 ± 87.51 a	816.01 ± 83.85 a	731.34 ± 67.46 b
	Female	602.06 ± 28.20 b	653.51 ± 62.04 a	646.86 ± 48.96 a	613.10 ± 59.54 b
Breast (g)	Male	203.26 ± 11.04 b	279.60 ± 18.29 a	270.59 ± 26.35 a	240.54 ± 34.52 a
	Female	155.22 ± 12.86 b	223.96 ± 13.99 a	220.90 ± 14.23 a	209.19 ± 14.16 a
Thigh (g)	Male	204.06 ± 10.30 b	246.21 ± 27.80 a	244.64 ± 28.57 a	216.18 ± 14.63 b
	Female	164.30 ± 9.48	188.60 ± 10.38	186.04 ± 10.33	171.61 ± 10.09
Wing (g)	Male	89.80 ± 4.29 b	105.48 ± 4.89 a	101.92 ± 4.76 a	91.27 ± 4.42 b
	Female	69.48 ± 3.76	75.94 ± 3.82	74.97 ± 3.77	70.99 ± 3.81
Back (g)	Male	119.85 ± 5.22 b	140.81 ± 5.57 a	136.19 ± 5.42 a	121.84 ± 5.41 b
	Female	95.13 ± 4.03 b	109.39 ± 4.22 a	107.96 ± 4.17 a	102.14 ± 4.11 b
Neck (g)	Male	16.43 ± 1.88 b	19.59 ± 1.92 a	18.84 ± 1.87 a	16.68 ± 1.89 b
	Female	11.62 ± 1.12	12.94 ± 1.18	12.61 ± 1.14	11.83 ± 1.16
Gizzard (g)	Male	19.79 ± 1.45 b	24.14 ± 1.56 a	22.93 ± 1.51 a	20.48 ± 1.46 b
	Female	17.34 ± 1.31	19.34 ± 1.39	18.95 ± 1.38	17.90 ± 1.34
Heart (g)	Male	7.96 ± 0.68 b	9.59 ± 0.76 a	9.14 ± 0.72 a	8.12 ± 0.74 b
	Female	5.42 ± 0.44 b	7.45 ± 0.54 a	6.15 ± 0.51 a	5.70 ± 0.48 b
Liver (g)	Male	17.65 ± 1.63 b	21.11 ± 1.79 a	20.24 ± 1.65 a	17.85 ± 1.64 b
	Female	16.74 ± 2.10 b	18.63 ± 2.22 a	18.31 ± 2.17 a	17.23 ± 2.13 b
Abdominal fat (g)	Male	3.01 ± 0.63 a	2.69 ± 0.59 b	2.77 ± 0.61 b	2.48 ± 0.61 b
	Female	6.29 ± 0.83 a	5.09 ± 0.82 b	5.30 ± 0.88 b	5.08 ± 0.78 b
Breast (%)	Male	32.47 ± 1.84	33.24 ± 0.53	33.16 ± 1.33	32.89 ± 2.58
	Female	33.76 ± 1.31	34.27 ± 2.05	34.15 ± 1.34	34.12 ± 4.78
Thigh (%)	Male	28.45 ± 0.90	29.27 ± 0.42	29.98 ± 0.09	29.56 ± 0.90
	Female	27.29 ± 0.83	28.86 ± 2.75	28.76 ± 1.65	27.99 ± 5.58
Wing (%)	Male	12.52 ± 0.55	12.54 ± 0.62	12.49 ± 0.53	12.48 ± 0.54
	Female	11.54 ± 0.54	11.62 ± 0.59	11.59 ± 0.55	11.58 ± 0.56
Back (%)	Male	16.71 ± 0.73	16.74 ± 0.80	16.69 ± 0.72	16.66 ± 0.69
	Female	15.80 ± 0.69	15.82 ± 0.71	15.77 ± 0.66	15.76 ± 0.62
Neck (%)	Male	2.29 ± 0.09	2.33 ± 0.11	2.31 ± 0.10	2.28 ± 0.09
	Female	1.93 ± 0.04	1.98 ± 0.06	1.95 ± 0.05	1.93 ± 0.05
Gizzard (%)	Male	2.76 ± 0.15	2.87 ± 0.18	2.81 ± 0.16	2.80 ± 0.16
	Female	2.88 ± 0.19	2.96 ± 0.21	2.93 ± 0.19	2.92 ± 0.19
Heart (%)	Male	1.11 ± 0.01	1.14 ± 0.02	1.12 ± 0.02	1.11 ± 0.01
	Female	0.90 ± 0.01	0.92 ± 0.01	0.95 ± 0.01	0.93 ± 0.01
Liver (%)	Male	2.46 ± 0.16	2.51 ± 0.19	2.48 ± 0.18	2.44 ± 0.18
	Female	2.78 ± 0.21	2.85 ± 0.23	2.83 ± 0.22	2.81 ± 0.22
Abdominal fat (%)	Male	0.42 ± 0.03 a	0.32 ± 0.02 b	0.34 ± 0.02 b	0.34 ± 0.02 b
	Female	0.88 ± 0.05 a	0.78 ± 0.04 b	0.82 ± 0.04 a	0.83 ± 0.04 a
Carcass yield (%)	Male	72.51 ± 1.04	72.63 ± 1.11	72.59 ± 1.09	72.56 ± 1.07
	Female	72.29 ± 0.99	72.36 ± 1.05	72.35 ± 1.08	72.31 ± 1.04

Values shown are mean ± SD (standard deviation). ^a,b: Means not sharing the same superscripts in a row were significantly different (Duncan’s multiple range test; p < 0.05).

and

Table 4. The effect of HSs on the content of nutrients in breast samples.

Nutrient	Sex	Control	0.50% HS	0.75% HS	1.00% HS
Dry matter (g)	Male	270.01 ± 4.45	271.36 ± 3.75	270.88 ± 3.65	270.29 ± 3.26
	Female	272.61 ± 2.86	273.31 ± 1.37	273.03 ± 3.40	273.23 ± 3.96
Crude protein (g)	Male	877.71 ± 18.07 b	892.85 ± 19.11 a	892.71 ± 20.25 a	893.29 ± 19.84 a
	Female	881.71 ± 19.86 b	898.11 ± 18.58 a	897.84 ± 19.69 a	899.93 ± 19.22 a
Fat (g)	Male	26.26 ± 3.01 a	24.65 ± 2.77 b	24.80 ± 2.06 b	26.68 ± 1.26 a
	Female	26.88 ± 3.46 a	24.83 ± 3.50 b	24.78 ± 3.83 b	26.16 ± 2.77 a
Energy (MJ)	Male	17.05 ± 0.22	16.72 ± 1.01	17.33 ± 0.19	17.09 ± 0.12
	Female	17.20 ± 0.35	17.09 ± 0.26	17.12 ± 0.32	17.09 ± 0.10
Ash (g)	Male	44.20 ± 0.81	44.53 ± 0.87	44.40 ± 0.45	45.28 ± 2.19
	Female	43.65 ± 0.89	43.99 ± 0.47	45.60 ± 1.53	46.31 ± 0.67

Values shown are mean ± SD (standard deviation). ^a,b: Means not sharing the same superscripts in a row were significantly different (Duncan’s multiple range test; p < 0.05).

. From the results, we confirmed that the diet affected a few carcass traits. In accordance with the higher carcass weight of the HS pheasants, the highest weights of body components were observed in the pheasant broilers of both sexes offered the 0.50 HS diet, followed by pheasants in the 0.75 HS and 1.0 HS groups. The control pheasant broilers had the lowest carcass characteristics.

In contrast, HS supplementation in the diets had no significant effect on the proportion of the carcass body, although the control pheasant broilers mostly had the lowest values of proportion.

The weights of the internal organs (liver, gizzard and heart) were significantly (p < 0.05) influenced by the 0.50 HS and 0.75 HS diets. However, the proportions of the internal organs from the carcass weight were similar (p > 0.05).

The diet had a significant effect (p < 0.05) on the abdominal fat weight of the broiler pheasants. Male pheasants fed the 1.0 HS diet typically had the lowest weight of abdominal fat in comparison with the other groups. In the female pheasants, we recorded a lower content of abdominal fat with the dose of 0.50 and 1.00 HSs in the diet.

The effect of the supplementation of pheasant broiler diets with HSs on the content of the nutrients in the breast and thigh muscle samples is shown in Table 4 and

Table 5. The effect of HSs on the content of nutrients in thigh samples.

Nutrient	Sex	Control	0.50% HS	0.75% HS	1.00% HS
Dry matter (g)	Male	259.41 ± 7.93	260.05 ± 8.73	259.73 ± 6.53	259.76 ± 8.27
	Female	262.05 ± 7.30	262.64 ± 7.28	261.70 ± 5.03	262.83 ± 4.78
Crude protein (g)	Male	754.66 ± 33.71 b	768.06 ± 35.86 a	772.60 ± 53.66 a	758.63 ± 31.45 b
	Female	740.80 ± 15.99 b	759.18 ± 17.07 a	755.94 ± 53.33 a	742.08 ± 19.91 b
Fat (g)	Male	141.25 ± 42.54 a	139.83 ± 37.27 b	139.28 ± 51.59 b	141.05 ± 23.05 a
	Female	144.51 ± 18.76 a	141.01 ± 12.16 b	141.51 ± 50.06 b	144.05 ± 23.05 a
Energy (MJ)	Male	18.73 ± 1.01	19.02 ± 0.82	19.53 ± 1.00	18.99 ± 0.51
	Female	19.73 ± 0.49	18.98 ± 0.26	20.47 ± 095	20.24 ± 0.52
Ash (g)	Male	45.51 ± 3.24	45.05 ± 2.60	44.84 ± 5.11	44.01 ± 1.14
	Female	42.80 ± 1.11	42.91 ± 1.58	42.11 ± 3.25	41.63 ± 1.90

Values shown are mean ± SD (standard deviation). ^a,b: Means not sharing the same superscripts in a row were significantly different (Duncan’s multiple range test; p < 0.05).

. The application of 0.50 and 0.75 of HSs to the diet of pheasant broilers for the 0.50 HS and 0.75 HS experimental groups led to a significant increase (p < 0.05) in the crude protein content in the breast and thigh muscle samples when compared with the control and 1.0 HS groups. The fat content of the breast and thigh muscle samples decreased only in the 0.50 and 0.75 HS groups (p < 0.05). Statistically significant differences among the diets supplemented with HSs in the dry matter and the energy and ash of the breast and thigh muscle samples were not observed (p > 0.05).

In the palmitic, oleic and stearic acids, only a tendency (p > 0.05) toward a lower content after nutritional supplementation was found. Similarly, a tendency (p > 0.05) toward higher palmitic, oleic and stearic acids in the thigh muscle was obtained from the pheasant broilers of both sexes in the control diet group.

The diet had an insignificant effect (p > 0.05) on the total FAs of the breast and thigh muscles (

Table 6. The effect of HSs on the content of fat acids in breast samples.

Fat Acid	Sex	Control	0.50% HS	0.75% HS	1.00% HS
Palmitic (g)	Male	36.82 ± 0.20	36.04 ± 0.57	35.83 ± 0.24	36.73 ± 0.50
	Female	35.57 ± 0.45	34.69 ± 0.79	34.52 ± 0.27	34.92 ± 0.35
Stearic (g)	Male	16.17 ± 0.13	15.09 ± 0.21	15.32 ± 0.08	15.53 ± 0.30
	Female	14.37 ± 0.22 a	14.17 ± 0.36 a	13.83 ± 0.11 b	13.94 ± 0.21 b
Oleic (g)	Male	27.95 ± 0.09	27.74 ± 0.38	27.88 ± 0.09	27.34 ± 0.28
	Female	29.87 ± 0.48	29.17 ± 0.77	29.81 ± 0.12	29.13 ± 0.19
PUFA (g)	Male	38.82 ± 0.33	39.78 ± 0.68	38.48 ± 0.37	39.11 ± 0.83
	Female	38.37 ± 0.58 b	39.28 ± 0.85 a	38.78 ± 0.40 b	38.89 ± 0.53 b
MUFA (g)	Male	29.95 ± 0.09	28.64 ± 0.38	28.98 ± 0.09	29.34 ± 0.28
	Female	29.89 ± 0.46	28.47 ± 0.77	28.87 ± 0.12	29.13 ± 0.19
SFA (g)	Male	56.27 ± 0.02	54.58 ± 0.37	55.99 ± 0.14	55.74 ± 0.17
	Female	57.86 ± 0.40	57.08 ± 0.37	57.51 ± 0.14	57.69 ± 0.12

Values shown are mean ± SD (standard deviation). ^a,b: Means not sharing the same superscripts in a row were significantly different (Duncan’s multiple range test; p < 0.05).

and

Table 7. The effect of HS on the content of fat acids in thigh samples.

Fat Acid	Sex	Control	0.50% HS	0.75% HS	1.00% HS
Palmitic (g)	Male	33.32 ± 0.30	32.99 ± 0.75	32.31 ± 1.71	32.89 ± 0.19
	Female	32.63 ± 0.33	31.75 ± 0.25	31.94 ± 0.26	32.13 ± 0.24
Stearic (g)	Male	11.33 ± 0.11	11.19 ± 0.27	11.28 ± 0.39	11.08 ± 0.07
	Female	9.82 ± 0.10	9.19 ± 0.08	9.04 ± 0.08	9.65 ± 0.06
Oleic (g)	Male	30.27 ± 0.16	29.87 ± 0.27	29.95 ± 3.67	29.33 ± 0.13
	Female	30.58 ± 0.14	30.45 ± 0.12	29.98 ± 0.20	29.17 ± 0.04
PUFA (g)	Male	35.44 ± 0.37	34.87 ± 1.02	34.79 ± 1.73	34.86 ± 0.18
	Female	34.91 ± 0.37	34.37 ± 0.30	34.14 ± 0.27	34.19 ± 0.35
MUFA (g)	Male	30.58 ± 0.14	30.12 ± 0.21	30.34 ± 3.64	29.95 ± 0.11
	Female	30.79 ± 0.12	30.70 ± 0.09	30.23 ± 0.16	29.57 ± 0.04
SFA (g)	Male	54.85 ± 0.34	53.09 ± 0.51	54.04 ± 2.45	53.74 ± 0.23
	Female	56.16 ± 0.26	55.18 ± 0.25	55.35 ± 0.27	55.51 ± 0.08

Values shown are mean ± SD (standard deviation).

). A tendency (p > 0.05) toward a higher PUFA content was found in the 0.50 HS group in the breast muscles of females. In MUFA as well as SFA, a tendency (p > 0.05) toward a lower content in the groups fed with HSs was found in the breast muscles. In the thigh muscle samples, after the nutritional supplementation with HSs, a tendency (p > 0.05) toward a lower content of PUFA, MUFA and SFA in the experimental groups was found.

4. Discussion

Consistent with our results, Kocabagli et al. [38], Abdel-Mageed [39], Mirnawati and Marida [40] and Elnaggar and El-Kelawy [41] noted that birds given diets with humic substances had a significantly higher value of dressing, breast and thigh percentages and a significant lower percentage of abdominal fat compared with a control diet. Nagaraju et al. [30] observed no significant differences in the dressing percentage, breast meat yield and abdominal fat, liver, heart and spleen weights between different doses of humic acids at the end of a 42-day experiment.

Ozturk et al. [31] found that the carcass traits of broiler chickens were not affected by the dietary treatments (7.5, 15.0 and 22.5 HS g/kg). According to Pistová et al. [42], broiler chickens fed a diet containing 1% humic acid had a significantly higher stomach weight compared with the control group, but the carcass, heart and liver weight as well as the carcass yield were not significantly affected by the humic acid addition. Arpášová et al. [43] did not recorded statistically significant changes in the carcass weight or breast and thigh percentages among the control group and the experimental groups with the addition of humic substances to diets. Arpášová et al. [44] found a statistically significant higher value of the heart weight in the experimental group with HSs compared with the control group.

Li et al. [45] reported that the addition of humic acid to broiler diets may be able to improve digestion dynamics and nutrient absorption, ultimately regulating the growth ability and changing the metabolism to enhance animal carcass traits.

According to the results of the present study, the feed mixture for broiler pheasants supplemented with HSs could have a significant effect on the chemical composition of the meat. A dose of 0.50% natural HSs tended to be more effective. The addition of dietary natural HSs to the diet of pheasants resulted in statistical differences in the crude fat and crude proteins of the breast meat samples (p < 0.05). Ozturk et al. [33] observed that the addition of 0.5, 1.0 and 1.5% HS concentrations had different effects on the fat and total protein content. The quality of the meat produced with the addition of HSs to feed mixtures for broilers could be evaluated as being valuable for human nutrition due to the higher content of proteins and fats [46]. Feeding with a diet containing 0.1% humic acid increased the protein in the meat compared with the control group. However, chicks fed a basal diet supplemented with 0.1% humic acid had significantly lower fat than other supplements and the control group [41]. The results of our study do not support these conclusions.

Haščík et al. [47] stated that the addition of HA did not affect the chemical composition of the breast muscle. The protein content was reduced in comparison with the control group. In the case of thigh muscles, they had a significantly higher content of fat and cholesterol in broiler chickens with addition of HA compared with the control group.

In our study, the predominant fatty acids were palmitic, oleic and stearic acids. This agreed with the findings from other studies [48,49]. Broilers fed the control diet had higher amounts of the most saturated fatty acids (SFA), especially myristic, myristolic and palmitic acids, which are important for their hypercholesterolemic properties related to coronary heart disease [49,50]. The inclusion of humic acid in the diet significantly increased the proportions of PUFA in the broiler meat. Haščík et al. [51] found that HA reduced the SFA content in the thigh muscles compared with the control group and increased the MUFA content in the HA-supplemented group. The content of PUFA in the thigh muscle increased after the addition of 2% HA to the diet compared with the control.

5. Conclusions

We concluded that feeding with a diet containing HSs could have a beneficial influence on several carcass characteristics, decrease the crude fat content in the meat and change the profile of fatty acids in the breast and thigh muscles of broiler pheasants. The addition of 0.50 and 0.75 HSs appeared to be a more effective option to improve selected meat quality parameters of broiler pheasants.