Growth Performance, Carcass Traits and Meat Quality of Slower-growing and Fast-growing Chickens Raised with and without Outdoor Access

Abstract

The objective of this study was to determine the effect of genotype (slower-growing vs. fast-growing) and production system (access to outdoors vs. indoor) on the growth performance, carcass yield and meat quality (chemical composition, physicochemical and sensory properties) of chickens. The experiment was performed on 1,040 day-old hybrid male chickens of two genotypes. Slower-growing chickens (Hubbard JA957, certified) and fast-growing chickens (Hubbard F15) were fed identical diets until 65 days of age. Both genotypes (each represented by 520 birds) were divided into two subgroups and were raised in pens on litter with outdoor access or in indoor confinement without outdoor access (four replications per subgroup, each of 65 birds). Until day 21, the birds stayed in the indoor facility, in deep-litter pens. The birds could forage on pasture 12 h daily, commencing at three weeks of age. Stocking density was 0.13 m 2 floor space per bird in pens on litter, and 0.8 m 2 per bird in grassy yards. Compared with fast-growing, slower-growing chickens were significantly lighter (by 17%), had a lower breast and thigh muscle yield and a higher abdominal fat content, but they were characterized by higher survival rates at 65 days, a higher protein content and a lower fat content of breast meat. Outdoor access had no negative effects on the growth performance, muscle yield, the fatty acid profile and oxidative status of meat lipids. The meat of free-range chickens was darker in color, it had a higher protein content and a better water-holding capacity, but it was less juicy than the meat of birds raised indoors. (

The effects of access to pasture on growth performance, behavioural patterns, some blood parameters and carcass yield of a slow-growing broiler genotype

“…On day 84, a lower live weight with a worse feed conversion rate was observed in broilers in outdoor groups in accordance with other studies (Castellini et al 2002a(Castellini et al , 2002bWang et al 2009). In contrast to our results, outdoor access did not affect the growth performance in previous studies (Jiang et al 2011;Mikulski et al 2011;Chen et al 2013). Our findings could be explained by some factors in the outdoor system such as environmental temperature, exercise, pasture intake (Chen et al 2013).…”

“…Besides, in the outdoor group as a result of activity, abdominal fat was found to be lower than the indoor group. Conversely, it was reported that access to outdoor did not have an effect on abdominal fat (Grashorn & Brose 1997;Mikulski et al 2011). …”

“…Accessing a pasture provides possibilities for broiler to exhibit their natural behaviours, for example, scratching, foraging, dust bathing, sun bathing, perching and activity. In this way, development and strength of bones are developed well and leg problems can be prevented largely (Mikulski et al 2011). While enrichment environmental conditions with higher welfare standards are maintained for slow-growing broilers, performance parameters like feed conversion ratio deteriorate compared to the conventional rearing system.…”

Linhagens de frangos caipiras criadas em sistema semi-intensivo em região de clima quente

“…Segundo Veloso et al (2014), isso pode prejudicar a comercialização destes animais, pois o consumidor brasileiro de frango caipira demanda principalmente o frango inteiro e uma carcaça não muito grande. O arraçoamento à vontade também pode fazer com que a ave não sinta a necessidade de procurar o alimento na área de pastejo disponível, podendo não adquirir atributos importantes esperados nestes animais, como coloração mais acentuada da carcaça e firmeza e sabor característicos da carne (Mikulski et al, 2011).…”

“…O bem-estar na produção de aves está diretamente relacionado com o sistema de criação (Moura et al, 2010;Fraser et al, 2013). O sistema de semiconfinamento permite que as aves tenham livre acesso às áreas de pastejo, para que estas expressem seus comportamentos naturais, resultando em diferenças particulares na qualidade da carne, quando comparadas com as aves criadas confinadas (Fanatico et al, 2007;Mikulski et al, 2011). Por outro lado, as condições ambientais podem interferir no bem-estar, saúde e comportamento das aves, podendo se refletir em suas características fisiológicas e produtivas (Fouad et al, 2008;Tan et al, 2010).…”