Lack of interrelationship between the effects of dietary factors and food withdrawal on carcase quality of broiler chickens

Abstract

1. Two factorial experiments were carried out with White Rock (Arbor Acres) female pullets, kept in layer cages, to evaluate the relationship between body weight (BW) at different ages and the amount of food allocated (FA) on laying performance. Differences in BW at the beginning of experiments 1 and 2 (12 and 18 weeks of age, respectively) were obtained by segregating pullets raised under the recommended FA into weight groups (WGs): standard (ST), light BW (LBW) and heavy BW (HBW). Each of the 3 WGs was further divided into 2 subgroups, raised either under the recommended FA or a moderately increased FA until 34 weeks of age. The experiments were terminated at approximately 65 weeks of age. 2. Body weight was significantly (P < 0.05) affected by WGs until 28 and 60 weeks, and by FA until 56 and 44 weeks of age in experiments 1 and 2, respectively. The increased FA significantly accelerated the age of onset of egg production and increased BW at that time. Neither of these variables was affected by BW at 12 weeks of age. BW at 18 weeks of age did not affect age of sexual maturity, but at that time the BW of the LBW- and the HBW-birds was significantly lower and higher, respectively, than that of the ST-birds. 3. Number of eggs per laying or per housed hen was not affected by the WG and/or FA. The exception was the significant interaction between the 2 factors in their effect on the number of eggs per laying hen observed in experiment 1, in which the increased FA prevented the decline in the HBW-birds. 4. The data suggest that the laying performance of broiler breeder hens segregated according to their weight at 12 or 18 weeks of age, and kept in layer cages is not affected by their weight at these ages, and thereafter. The effects of a moderate increase in FA, and of the interaction between this factor and WGs, on laying performance, are not straightforward.

Desempenho e composição corporal de frangos de corte alimentados com diferentes níveis de proteína e de aminoácidos ou com livre escolha das dietas

“…com relações calórico-protéicas mais estreitas proporcionam carcaças mais magras (Leeson & Summers, 1997;Bartov, 1998;Bartov & Plavnik, 1998). Neste estudo, este efeito foi mais evidente para ganho de proteína que de gordura (Tabela 5).…”

“…Dietas com relações calórico-protéicas mais amplas (menos proteína) promovem maior consumo de energia ou ingestão deficiente de proteína. Por outro lado, para dietas com relações mais estreitas (mais proteína), o consumo de energia é menor, o crescimento magro é máximo e as carcaças são mais magras (Rosebrough & Steele, 1985;Summers et al, 1988, Leeson & Summers, 1997Bartov, 1998). Reginatto et al (2000) observaram que dietas com relações mais amplas entre energia e proteína não alteraram o ganho de peso, mas resultaram em pior conversão calórica.…”

Effects of breed, sex and diet and their interactions on carcass composition and tissue weight distribution of broiler chickens

“…Also, carcass leanness can be achieved by feeding animals and birds low energy, low-cost high fibrous diets and by restricted feeding (GODFREY et al, 1991;LEESON et al, 1992;LEESON et al, 1996;KHANTAPRAB et al, 1997). Separate effects of breed, sex and nutrition on carcass composition of chickens were reported by BROADBENT et al (1981); ORR et al (1984); MARKS (1990); BARTOV (1998); SMITH and PESTI (1998) and WISEMAN and LEWIS (1998). Variation in lean, bone and fat distribution due to breed have been investigated by ABDALLAH et al (1990), SHAHIN et al (1990) and SHAHIN et al (1996).…”

Jejum alimentar na qualidade da carne de frangos de corte criados em sistema convencional

“…O aumento dessa perda é linear à medida que aumenta a duração do jejum (BARTOV, 1998;PAPA, 1991). A desidratação também tende a influenciar a qualidade da carne de aves, pois a retenção de água é uma característica importante que está relacionada com o aspecto da mesma antes do cozimento, com seu comportamento durante a cocção e com a palatabilidade do produto (MENDES, 2001).…”