Carcass yield of naked neck, french hillbilly stone gray rolled (pedrés) chickens fed various energy levels^

Introduction

Every day, the poultry industry gets larger and larger shares in world's meat market. Therefore, the poultry production has become the target of attempts to improve animal management/housing, due to pressures from a major part of consumers who search for healthier, less polluting foods while promoting animal welfare (Sheppard and Edge, 2005).

Due to their slow body development, hillbilly (hick)-type chickens have different meat color, flavor, and texture when compared to industrial broilers, thus adding a differentiated value to the end product. Currently, interest is growing for increased carcass yields, heavier breasts and thighs, and meat quality meeting consumer demands (Mendes et al., 2004). Knowing the chemical/energy composition of feedstuffs is necessary to produce feeds with the right nutrient levels to meet animal requirements, with no excess or deficiency, leading to maximum productivity (Mello et al., 2009).

Considering that feed represents nearly 70% of total production cost, and that animal performance is related with dietary energy levels, research to fulfill bird nutritional requirements at a low cost is needed. The objective of this study was to evaluate carcass traits of naked neck, French Hillbilly Stone Gray Rolled (Pedrés) chickens fed rations containing various levels of metabolizable energy (ME).

Materials and Methods

The experiment was carried out in an experimental house granted to Federal Rural University of Amazonia (UFRA), located in Parauapebas, PA, Brazil. One hundred and ninety two (192) naked neck, French Hillbilly Stone Gray Rolled, both sexes, day-old chickens were grown under an intensive production system. The experimental design was completely at random, with 3 treatments and 8 repetitions each. Treatments (T) included different ME levels in the starter (1 - 28 days) and grower (29 - 90 days) feeds, as follows: T1: 3,000/3,100 Kcal ME/Kg; T2: 3,100/3,200 Kcal ME/Kg; T3: 3,200/3,300 Kcal ME/Kg. Feeds were manufactured using conventional ingredients including corn, soybean meal, soybean oil, meat meal, limestone, dicalcium phosphate, sodium chloride, and a mineral/vitamin premix.

The study was performed in an experimental house measuring 32.0 x 13.0 m, covered with wire mesh. Side walls were 1.0 m tall and maximum house height was 3.5 m. The floor was covered with wood s litter, and in each pen one hanging feeder and one pressure drinker were set. After arrival in the experimental facilities, chicks were selected and weight in order to obtain homogeneous 16-bird lots then distributed at random among the pens, as per the treatments and repetitions.

At 77, 84, and 90 days of age, two birds per pen were identified using numbered rings, fasted for 12 hours, killed (bleeding), plucked, and eviscerated. The variables studied were carcass yield, fine edible cuts (breast, thighs, legs) and other cuts (wings, back, feet, and head+neck). Yield calculations were made in relation to hot carcass weight.

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

Results and Discussion

Dietary ME levels and the various ages at processing did not influence carcass yield or those of breast, thighs or legs (Table 1) At 77 days of age, regardless of the ME level, birds reached their maximum potential.

Table 1. Carcass yield and breast, thigh, leg yields of naked neck, French Hillbilly Stone Gray Rolled (Pedrés) chickens fed different levels of metabolizable energy, processed at 3 different ages

Treatments	Processing age
77 days	84 days	90 days	CV (%)
	Carcass (%)
T1 - 3,000/3,100 Kcal ME/Kg	78.97	81.09	79.60	9.62
T2 - 3,100/3,200 Kcal ME/Kg	83.95	87.69	79.65	7.84
T3 - 3,200/3,300 Kcal ME/Kg	82.88	84.63	79.59	5.62
CV (%)	9.16	8.95	1.58
	Breast (%)
T1 - 3,000/3,100 Kcal ME/Kg	23.09	22.18	22.15	8.47
T2 - 3,100/3,200 Kcal ME/Kg	23.40	22.01	23.04	12.97
T3 - 3,200/3,300 Kcal ME/Kg	25.18	21.24	23.88	13.53
CV (%)	14.66	8.86	7.95
	Legs (%)
T1 - 3,000/3,100 Kcal ME/Kg	13.43	13.93	14.13	7.14
T2 - 3,100/3,200 Kcal ME/Kg	14.18	13.31	13.45	13.80
T3 - 3,200/3,300 Kcal ME/Kg	14.15	13.62	13.69	17.80
CV (%)	18.60	7.55	8.46
	Thighs (%)
T1 - 3,000/3,100 Kcal ME/Kg	13.38	13.68	13.47	8.03
T2 - 3,100/3,200 Kcal ME/Kg	14.47	13.71	13.53	13.76
T3 - 3,200/3,300 Kcal ME/Kg	14.05	12.15	13.79	17.02
CV (%)	15.95	10.19	7.79

^{Means show no statistically significant differences in accordance with Tukey's test (P>0.05).}

Mendonza et al. (2005) reported similar results from their studies about ME levels male ISA Label broilers, with no significant effect on edible cut yields. Our results agree with those of Mendes et al. (2004) who found no significant differences in carcass yield or edible cuts when using 6 different ME levels (2,900, 2,960, 3,020, 3,080, 3,140 and 3,200 Kcal/Kg), in the diets of Ross 308 broilers.

No significant effects were seen in the yields of wings, back, feed, or head+neck (Table 2).

Murarolli et al. (2009), studied the yields of various carcass cuts (wings, leg+thigh, breast, head, feet, back) in Cobb females fed rations with 6 different ME levels (3,250, 3,400, 3,500, 2,820, 2,925, 3,000 Kcal/Kg) found no significant effects.

Neto et al., (2000) used 5 Me levels (3,000, 3,075, 3,150, 3,225 and 3,300 Kcal/Kg feed) in Hubbard broilers and found similar results, where the absolute weights or cut yields were not influenced by ME levels, with the exception of carcass weight, that did vary (P<0.04) in a quadratic fashion in function of the various dietary ME levels.

Table 2. Relative weights of wings, back, feet, head+neck in naked neck, French Hillbilly Stone Gray Rolled (Pedrés) fed various ME levels, processed at different ages

Treatments	Processing age
77 days	84 days	90 days	CV (%)
	Wings (%)
T1 - 3,000/3,100 Kcal ME/Kg	11.37	14.68	10.58	45.61
T2 - 3,100/3,200 Kcal ME/Kg	11.77	10.90	10.97	12.07
T3 - 3,200/3,300 Kcal ME/Kg	11.72	10.48	10.70	13.74
CV (%)	12.91	42.19	5.16
	Back (%)
T1 - 3,000/3,100 Kcal ME/Kg	22.07	20.89	20.31	7.61
T2 - 3,100/3,200 Kcal ME/Kg	22.91	22.00	19.82	17.19
T3 - 3,200/3,300 Kcal ME/Kg	22.55	23.02	18.75	16.02
CV (%)	18.75	9.60	8.42
	Feet (%)
T1 - 3,000/3,100 Kcal ME/Kg	4.79	4.72	4.50	14.74
T2 - 3,100/3,200 Kcal ME/Kg	5.18	4.64	4.63	19.82
T3 - 3,200/3,300 Kcal ME/Kg	5.07	4.43	4.38	20.44
CV (%)	19.49	17.46	15.73
	Head + Neck(%)
T1 - 3,000/3,100 Kcal ME/Kg	9.49	9.49	9.49	29.19
T2 - 3,100/3,200 Kcal ME/Kg	10.49	10.49	10.49	17.83
T3 - 3,200/3,300 Kcal ME/Kg	10.31	10.31	10.31	17.18
CV (%)	19.71	26.85	12.91

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

Conclusions

Dietary metabolizable energy levels did not influence the carcass yield or carcass cut yields of naked neck, French Hillbilly Stone Gray Rolled (Pedrés) chickens.

Bibliography

Mello HHC, Gomes PC, Rostagno HS, Albino LFT, Souza RM, Calderano AA. 2009. Valores de energia metabolizável de alguns alimentos obtidos com birds de diferentes idades. Revista Brasileira de Zootecnia 38(5):863-868.

Mendes AA, Moreira J, Oliveira EG, Garcia EA, Almeida MIM, Garcia RG. 2004. Efeitos da Energia da Dieta sobre Desempenho, Rendimento de Carcaça e Gordura Abdominal de Frangos de Corte. Rev. Bras. de Zootecnia 33(6):2300-2307.

Mendonça MO. 2005. Níveis de energia metabolizável para birds de corte de crescimento lento criadas em sistema semiconfinado. Jaboticabal, SP: UNESP. 114p. Tese (Mestrado em Nutrição de Monogástrico) - Universidade Estadual Paulista.

Murarolli RA, Alburqueque R, Kobashigawa E, Murarolli VDA, Trindade neto MA, Araújo LF. 2009. Efeitos de diferentes relações dietéticas de energia metabolizável: proteína bruta e do peso inicial de pintos sobre o desempenho e o rendimento de carcaça em frangos de corte fêmeas. Braz. J. vet. Res. anim. Sci. 46(1):62-68.

Neto ARO, 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. Revista Brasileira de Zootecnia 29(4) July/Aug.

SAEG Sistema para Análises Estatísticas. 2007. Versão 9.1. Fundação Arthur Bernardes- UFV-Viçosa.

Sheppard A & Edge S. 2005. Economic and operational impacts of the proposed EU directive laying down minimum standards for the protection of chickens kept for meat production. Exeter: Research undertaken for Defra by the University of Exeter Centre for Rural Research and ADAS, 246p.

MSV Santos*¹, FB Tavares², AS Moreira³, SS Vieira⁴, PA Andrade⁵, JPB Loureiro³^Project Financed by FAPESPA, ¹Professor Animal husbandry Graduate Course, Federal Rural University of Amazonia, Parauapebas Campus, Brazil; ²Masters Undergraduate, Amazonia Animal Health and Production, Animal Husbandry Professional, Federal Rural University of Amazonia, Parauapebas Campus, Brazil; ³Masters Undergraduate Amazonia Animal Health and Production; ⁴Scholarship Holder, PIBIC/CNPQ/UFRA; ⁵Academicians, Animal Husbandry Graduate Course, Federal Rural University of Amazonia, Parauapebas Campus, Brazil.