Year: 2001
Type: article
Abstract: The effects of food restriction on behaviour, endocrine and metabolic parameters were studied in immature (13 weeks old) female breeding birds of the meat-type chickens (broiler breeders).Ad libitum fed hens were compared with those subjected to one qualitative (diet diluted with 30 % hardwood sawdust) and two quantitative (the daily ration recommended by the breeding company and twice that amount) food restriction treatments.Behaviour of quantitatively restricted hens provided with one daily meal showed marked diurnal variation, while that of hens with free access to food (ad libitum fed and qualitatively restricted) was more evenly distributed throughout the day.There were elevated plasma corticosterone concentrations in hens subjected to intensive quantitative restriction.Although an increase in corticosterone concentrations of hens subjected to qualitative food restriction was lower, it was significant in comparison with ad libitum control, indicating that even mild qualitative food restriction is stressful.Compared to ad libitum fed hens, there were decreased plasma T 3 concentrations in all food restriction treatments, while plasma T 4 concentrations increased in intensively quantitatively restricted hens.Food restriction did not affect plasma glucose and total proteins, whereas triacylglycerol levels were decreased and cholesterol increased as a consequence of restriction.Creatinine level was increased in hens with less intensive quantitative restriction and plasma concentration of uric acid was decreased in qualitatively restricted hens in comparison with all other treatments.These results suggest that although behaviour of qualitatively restricted-fed hens resemble more to that of ad libitum-fed hens, their physiological status reminds more quantitatively restricted ones. Domestic chicken, welfare, corticosterone, thyroid hormonesThe major welfare problems in meat type chickens (broilers) are those, which can be regarded as side effects of the intense selection for growth and food conversion.These include leg disorders, contact dermatitis, ascites and sudden death syndrome in growing birds.It is apparent that the fast growth rate of current broiler strains is not accompanied by a satisfactory level of welfare including health (Report of the Scientific Committee on Animal Health and Animal Welfare of the EU Commission 2000).High body weight of ad libitum fed (like the progeny) breeding birds (broiler breeders) is associated with excessive fat deposition, lameness, high mortality associated with skeletal and heart disease (Katanbaf et al. 1989; Savory et al. 1993;Hocking 1999), impaired immune function (Han and Smyth 1972;O'Sullivan et al. 1991; Hocking et al. 1996), and reduced fertility in both sexes (Nestor et al. 1980;Hocking et al. 1987;Hocking and Duff 1989;Robinson et al. 1993).In order to limit the body weight of breeding birds at sexual maturity (about 24 weeks of age), to reduce related health problems, and to increase fertility, the chronic food restriction is applied routinely in commercial conditions.The main welfare problems of broiler breeders are related to the severe food restriction.
Source: Acta Veterinaria Brno
Authors: Ľ. Kubíková, P. Výboh, Ľ. Košťál
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
SDG: Zero hunger
Open Access status: hybrid
OpenAlex ID: W2018937679