The effect of energy levels on the performance of naked neck, french hillbilly stone gray rolled (pedres) chickens in the growing phase^

Introduction

Consumers all around the world have adopted nutritional habits based on what they consider more natural, healthier foods. This has resulted in a constant expansion in the so called alternative poultry production, using country type, peasant, or hick broilers and hens (Varco et al., 2000; Fraser, 2001).

This farming system is characterized by using family man power, small pieces of land, and a great capacity to transform grains and other plant products into meat and eggs, thus allowing for the participation of women and children, since related tasks can be easily managed. It is worthy to notice that hillbilly chickens do not compete (either in production scale or production cost) with industrial broilers, but they do in terms of meat quality/flavor, serving a market niche that can afford to pay premium prices for these traits (Gessulli, 1999).

In recent years, we have learned more and more about the nutritional value of feedstuffs, and also about animal nutritional requirements in their various productive phases (Rostagno, et al., 2007). Only a few of these studies have used slow-growing birds. This study had the objective of analyzing the effect of feed metabolizable energy (ME) on the performance of French Hillbilly, Stone-Gray Rolled, Naked Neck chickens (Caipira Francés Pedrés), in the grow out phase.

Materials and Methods

The study was carried out in an experimental facility located in Parauapebas City, PA, Brazil. One hundred and ninety two broilers of the above mentioned genotype were housed at a stocking density of 6.4 birds/m².

Birds were allotted to pens at the rate of 16 animals per pen, under an intensive system. The experimental design was completely at random, including 3 treatments and 4 repetitions each. Treatments (T) consisted of different dietary energy levels, as follows: T1: 3,100 Kcal ME/Kg; T2: 3,200 Kcal ME/Kg; T3: 3,300 Kcal ME/Kg. The composition of experimental feeds is shown in Table 1.

Table 1. Composition of the experimental feeds for chickens in the growing phase (29-90 days)

Ingredients	T1	T2	T3
Corn	63.24	60.95	58.66
Soybean meal	27.20	27.60	27.90
Plant oil	2.60	4.50	6.40
Meat meal	5.70	5.70	5.80
Limestone	0.36	0.35	0.34
Salt, NaCl	0.30	0.30	0.30
*Polimax F-2^()**	0.60	0.60	0.60
Total	100.00	100.00	100.00
Calculated nutritional composition
Met energy, Kcal/Kg	3,100	3,200	3,300
Crude protein, %	20.00	20.00	20.00
Ether extract, %	5.83	7.64	9.45
Crude fiber, %	3.29	3.27	3.24
Mineral matter, %	5.08	5.08	5.08
Lysine, %	1.07	1.08	1.08
Calcium, %	1.00	1.00	1.00
Total phosphorus, %	0.67	0.66	0.66
Available P, %	0.48	0.48	0.48
Sodium, %	0.17	0.17	0.17

^{(*) Composition per Kg of product: Vit. A - 1,835.000 IU; Vit. D3 - 335,000 IU; Vit. E - 2,835 mg; Vit. B1 - 335 mg; Vit. B2 - 1,000 mg; Vit. B6 - 335 mg; Vit. K3 - 417 mg; Vit. B12 - 2,500 μg; Biotin - 17 mg; Folic acid- 135 mg; Niacin - 6,670 mg; Selenium - 35 mg; Antioxidant - 2,000 mg; Calcium pantotenate - 1,870 mg; Copper - 1,000 mg; Cobalt 35 mg; Iodine - 170 mg; Iron 8,335 mg; Manganese - 10,835 mg; Zinc - 8,335 mg; Choline chloride 50% - 135,000; Methionine- 267,000 mg; Coccidiostat - 13,335 mg; Growth promoter- 16,670.}

Prior to experiment start, house and equipment were cleaned and disinfected. Chickens were vaccinated in the hatchery against Marek''''''''''''''''s disease and fowl pox, and at the age of 7 days they were vaccinated against Newcastle disease. During the early days of the experiment, heat was provided using 60W bulbs.

At housing, birds were weighed in order to form homogeneous experimental groups then distributed in the pens as per the identification of treatments and repetitions. Water and feed were given ad libitum throughout the experimental period. Management of internal pen temperatures was done watching both ambient temperature and animal behavior. The lighting program provided 24 hours continuous artificial light per day, throughout the experimental period.

The variables studied included end weight, feed intake, weight gain, feed conversion rate, crude protein intake, metabolizable energy intake, energy efficiency and protein efficiency.

Performance data was recorded weekly, and cumulative performance results (29-90 days of age) were analyzed. In order to determine body weights, birds in each pen were weighed together both at arrival and weekly. Weight gain was determined by the difference between end weight and start weight. Feed intake was calculated by the difference between total feed consumed and feed leftovers at the end of each period. Feed conversion rate was calculated by the proportion between total feed intake and weight gain in the period. In order to calculate the crude protein intake and metabolizable energy intake (Kg/bird), feed intake was multiplied by the concentration of both protein and metabolizable energy in the centesimal composition of feed, respectively. Protein efficiency and energy efficiency were calculated by multiplying the proportion of protein intake and ME intake times weight gain.

Results were analyzed using the ANOVA procedure for a completely-at-random model, with the "Statistical and Genetic Analysis System" (SAEG, 2007). The differences among the means of variables analyzed were compared using Tukey´s test (P<0.05).

Results and Discussion

No statistically-significant differences were observed in the means of weight, feed intake, weight gain or feed conversion rate of the birds fed various ME levels (Table 2). These results differ from those reported by Avila et al. (2005) who, evaluating ME level effects (2,600, 3,000 and 3,200 Kcal ME/Kg feed) on the performance of slow-growing Isa Label broilers, fed ad libitum, reported that ME levels resulted in decreased feed intake but produced the largest weight gain in the birds during the period of 21 to 84 days of age.

In an experiment carried out with broilers in the period of 44 - 55 days of age, Araújo et al. (2005) observed that weight gain was improved and feed conversion rate was lower as feed ME levels were increased (3,200, 3,400 and 3,600 Kcal ME/Kg feed).

Table 2. Performance of French Hillbilly Stone Grey Rolled, Naked Neck chickens fed rations containing 3 different energy levels in the growing phase (29 - 90 days of age)

Variables	T1	T2	T3	CV (%)
Mean weight(g)	3,192.00	3,117.50	3,100.25	4,094
Feed intake	5,730.75	5,646.75	5,530.00	6,881
Weight gain (g/bird)	2,728.25	2,547.00	2,562.50	5,454
Feed conversion rate	2.09	2.21	2.15	3,805

^{The means showed no statistically-significant differences, as per Tukey''''''''''''''''s test (P>0.05).}

In agreement with Sakomura et al. (2004), lipid supplementation in the feed promotes increased caloric density, an extra-caloric effect that consists of increasing the availability of ration nutrients, and an extra-metabolic effect of fat, resulting in improved energy efficiency due to the increased liquid energy in the diet. Massi (2007) reported that increasing dietary energy levels by including soybean oil results in an extra-caloric effect, resulting in increased nutrient availability for production which, in this particular case, refers to meat production. Nevertheless, analyzing the data of our research, this result did not occur.

The various feed energy levels did not influence crude protein intake, Me intake, protein efficiency or energy efficiency (Table 3). Oliveira et al (2000) reported different results when using a controlled diet in equal amounts among treatments (2,850, 2,925, 3,000, 3,075, 3,150 Kcal/Kg) and they observed a linear increase in ME intake (P<0.01) as dietary ME level increased. These authors also reported no effect on crude protein intake, which can be explained by the fact that they used isoprotein rations, and feed intake did not vary significantly among treatments.

Table 3. Protein and energy efficiency in Naked Neck, French Hillbilly Stone Gray Rolled Chickens fed 3 different energy levels, in the growing phase (29-90 days of age)

Variables	Treatments
T1	T2	T3	CV (%)
Crude protein, g/bird/day	18.20	17.92	17.55	6.881
Metabolizable energy intake, Kcal/bird/day	281.99	277.85	272.11	6.881
Protein efficiency	0.42	0.44	0.43	3.805
Energy efficiency	0.15	0.14	0.15	3.623

^{The means show no statistically-significant differences as per Tukey''''''''''''''''s test (P>0.05).}

Conclusions

Dietary metabolizable energy levels (3,100, 3,200 and 3,300 Kcal ME/Kg) did not influence the performance of Naked Neck, French Hillbilly Stone Gray Rolled (French Pedrés) chickens in the grow out period.

Bibliography

Araújo LF, Junqueira OM, Araújo CSS, Barbosa LCGS, Ortolan JH, Faria DE, Stringhini JH. 2005. Energy and lysine for broilers from 44 to 55 days of age. Revista Brasileira de Ciência Avícola 7(4).

Avila VS, Coldebella A, Figueiredo EAP, Brum PAR, Pissaia JA. 2005. Frangos de corte tipo caipira ou colonial, "Isa Label", criados com diferentes níveis de energia metabolizável em dois sistemas de criação. Comunicado Técnico 394. Embrapa suínos e birds. Concórdia.

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Massi PA. 2007. Energia metabolizável para frangos de corte de diferentes potenciais de crescimento criados em sistema de semiconfinamento. Seropédica. Rio de Janeiro. Universidade Federal Rural do Rio de Janeiro. Instituto de Zootecnia.

Rostagno HS, Bünzen S, Sakomura NK, Albino LFT. 2007. Avanços metodológicos na avaliação de alimentos e de exigências nutricionais para birds e suínos. R. Bras. Zootec. 36(suplemento especial):295-304.

Sakomura NK, Longo FA, Rabelo CB, Watanabe K, Pelícia K, Freitas ER. 2004. Efeito dos níveis de energia metabolizável da dieta no desempenho e metabolismo energético de frangos de corte. Revista da Sociedade Brasileira de Zootecnia 33(3 supl 1).

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Oliveira Neto AR, Oliveira RFM, Donzele JL, Rostagno HS, Ferreira RA, Carmo HM. 2000. Níveis de Energia Metabolizável para Frangos de Corte no Período de 22 a 42 Dias de Idade Mantidos em Ambiente Termoneutro. Rev. bras. Zootec. 29(4):1132-1140.

Vercoe JE, Fitzhugh, HA, Kaufmann R. 2000. Livestock production systems beyond 2000. Asian-Australasian Journal of Animal Sciences 13(5):411-419.

FB Tavares²*, MSV Santos¹, AS Moreira³, SS Vieira⁴, PA Andrade⁵, HS da Costa⁵^Project Financed by FAPESPA, ¹Professor, Animal Husbandry Graduate Course, Federal Rural University Amazonia, Parauapebas Campus, Brazil; ²Masters Undergraduate, Amazonia´s Animal Health and production, and Animal husbandry Professional, Federal Rural University of Amazonia, Parauapebas Campus, Brazil; ³Masters Undergraduate Amazonia´s Animal health and Production; ⁴Scholarship Holder, PIBIC/CNPQ/UFRA; ⁵Academicians, Animal Husbandry Graduate Course, Federal Rural University of Amazonia, Parauapebas Campus, Brazil.