Testing a Caliper for Measuring Thickness of the Abdominal Region in Live Broiler Chickens

There is a continuing effort to develop a nondestructive method for selecting broiler breeders against abdominal fat. The purpose of this experiment was to test a caliper for measuring thickness of leaf fat between the cloaca and abdominal surface on live broilers and to correlate thickness measurements with abdominal fat weight. Thickness on left and right sides of the abdomen were measured on 108 males at 40 days of age at 20 mm cloacal depth and 108 full-brothers at 47 days of age at 20 mm and 35 mm cloacal depths and on the midline of the abdomen at 35 mm cloacal depth. Broilers were slaughtered the following day and abdominal fat weights were recorded. Means of left and right sides were 2.96 mm (40 days), 4.24 mm (47 days) at 2 0 mm, and 4.17 mm (47 days) at 35 mm. Mean of two measurements on the midline of the abdomen was 4.84 mm at 35 mm. Correlation coefficients (r) between mean caliper measurements for both sides and abdominal fat weight were .29 (41 days) and .45 (48 days) at 20 mm and .54 (48 days) at 35 mm. At the midline of the abdomen, r = .30 (48 days) at 35 mm. These correlations indicate that mean caliper measurements on left and right sides of the abdomen at 35 mm cloacal depths might be used in a selection index for live broiler breeders to decrease abdominal fat.