|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2007
Publication Date: N/A
Citation: Interpretive Summary: Beak trimming is a common management practiced carried out today in many poultry farms in the United States. The main reason for beak trimming is that many commercial laying strains exhibit aggressive behaviors towards cage mates, leading to severe feather pecking. It can also lead to severe injury and death by cannibalism. The practice of beak trimming has many welfare concerns in that it prevents the chicken from carrying out natural behaviors. The beak is a complex organ, rich in nerve tissue. The beak trimming procedure itself may cause pain to the bird immediately after the procedure, and later in life due to the development of neuromas in the beak. Quality of trimming is a major concern, improving the quality of trimming may reduce the pain experienced by the birds. Young chicks vary in body weight and beak size, thus causing over- and under-trimming. Over trimming is excessive trimming of the beak and is often associated with neuromal development, while under-trimming can result in a second trimming later in life due to beak re-growth. The aim of this project was to determine if a relationship or correlation existed between body weight and beak size of the chicken. If such a relationship did exist, then body weight could be used as an indicator of beak size. It would be possible to adjust the beak trimmer to correspond to the size of the bird and improve beak trimming quality, as well as the well-being of the bird. In this study, results indicated that body weight was not a practically meaningful indicator of beak size. Future studies will be necessary to find an easily measurable trait that has a strong relationship with beak size, which can be used as a reliable indicator. These results can be used by other scientists when planning or interpreting their studies.
Technical Abstract: Beak trimming is a routine practice used in laying hens to prevent feather pecking and cannibalism. The effects of beak trimming on bird well-being depend on multiple factors, including the length of beak that is trimmed and the quality of the procedure. The aim of this work was to determine if a relationship existed between body weight and beak characteristics in one-day-old chicks with a future aim to develop an automated system for standardizing beak trimming. Three hundred and forty-four one-day-old chicks (Hy-line W-36) were sorted into three categories based on their body weight (heavy, intermediate, and light), and their beaks were photographed. Dimensional measures of beaks were calculated using MCID imaging software, including the lengths of the culmen, gonys, maxillary tomia (maxi), mandibular tomia (mand), and the width of the upper and low mandible measured at 2 mm (UM2, LM2), 3 mm (UM3, LM3), and 4 mm (UM4, LM4) from the tip of the upper and lower beaks. Correlations between body weight and beak measures were evaluated using Pearson product moment, Spearman rank-order, Kendall’s tau, and Hoeffdings Dependency. Results showed there were no significant correlations between beak dimensions and body weight in the light body weight group. In contrast, correlations were present between mandibular tomia and UM4 (P < 0.05) as well as LM 2 – 4 (P < 0.05) in the intermediate body weight group. In the heavy body weight group, body weight was positively correlated with mand (P < 0.05), gonys (P < 0.05), LM2 and LM3 (P < 0.05). However, in general, these correlations were too low (all below 0.29) to have any practical use for predicting beak size. Overall, the data indicated that body weight cannot be used as a reliable predicator of beak size in one-day-old Hy-line W-36 chicks.