Lean Line Research Articles

Selecting broilers for low or high abdominal fat: Initial observations

1. Two lines of broiler breeders were selected for three generations using a high (fatty line) or a low (lean line) ratio of abdominal fat to live weight as criterion in males at 9 weeks of age. 2. The heritability of this character remained high in both lines. 3. By the third generation, the progress achieved was much more marked in males than in females. The difference between the females of both lines was nevertheless significant. 4. The differences between the two lines were already discernible at 4 weeks of age. 5. Selecting for low or high abdominal fat content was accompanied by a better food conversion ratio in males of the lean line. 6. Selecting for the amount of abdominal fat produced similar effects on the other fatty deposits.

Comparison of a Lean and Fat Line of Swine for Muscle Processing Characteristics

Twenty-four crossbred pigs, 12 from a fat strain and 12 from a lean strain, were used in the first part of the study. Four pigs from each line were slaughtered at 91,104 and 118 kilograms. The right ham from each carcass was separated into three muscle sections, and the fluid was collected from these sections during 48-hr storage at 2 C. The specific gravity of the fluid was determined and the percentages of fluid and cooking loss were calculated. Ham muscle sections from heavier pigs yielded exudative fluid higher in total solids than hams from the lighter weight group. No significant differences were obtained between strain or weight groups for percentage processing loss from these sections. Correlation coefficients were significant and positive between percentage muscle in the carcass and percentage fluid exuded from the ham muscle sections. In the second part of the study, 50 hams with a wide range in color and firmness scores were separated into three muscle sections and the drip collected for sodium, potassium and specific gravity determinations. Also, the percentage of fluid exuded and processing loss were determined. A significant difference existed for percentage fluid eluted between the three muscle sections and the sodium content in the eluted fluid was significantly influenced by muscle section. There was a significant correlation between the fluid specific gravity and the percentage fluid eluted from the fresh ham sections (r = −.61).