INSECTICIDE RESIDUES437 producers being careful in selecting and buting feeds that are free of chlorinated insecticide residues, for use in their poultry operations. SUMMARY 1. Supplying the equivalent of 0.1 to 0.15 p.p.m. of lindane, dieldrin, heptachlor and DDT in the feed to laying hens in capsule form for 14 days resulted in some residues in chicken tissues which disappeared rapidly.2. Supplying the equivalent of 10 to 15 p.p.m. of the same insecticides in the feed for 5 days resulted in significant residues in eggs and abdominal fat which were extremely persistent.3. Care in feeding residue free feeds to laying flocks is extremely important.

SUMMARY— Longissimus dorsi (two positions), biceps femoris, gluteus medius, and rectus femoris muscles from 16 Charolais‐Hereford crossbred and 16 Hereford straightbred heifers on supplements of Vitamin A ranging from 0 to 6000 I.U. per lb ration were analyzed in the raw state. From 12 of the Charolais‐Hereford crossbred and 12 of the Hereford straight‐bred carcasses, loin steaks at three positions within the longissimus dorsi muscle were analyzed after cooking. Phosphorylated compounds having absorbance at 248 mμ, hypoxanthine‐uric acid, pH, and total moisture were determined in both raw and cooked tissue. In raw tissue, phosphorylation was higher and hypoxanthine‐uric acid was lower for longissimus dorsi than for the other muscles (P < .01). Differences between two positions in longissimus dorsi muscle were statistically nonsignificant. Significant differences (P < .05) were found for hypoxanthine‐uric acid and pH among Vitamin A supplements by analysis of variance techniques. Charolais‐Hereford crossbred heifers tended to have larger quantities of hypoxanthine‐uric acid than did Hereford straightbred heifers. In cooked loin steaks a breed × vitamin supplement linear interaction was significant (P < .051 for hypoxanthine‐uric acid, pH, and intensity of flavor and a quadratic trend (P < .05) for total moisture. Among steak positions, hypoxanthine‐uric acid differences were significant (P < .011 and there was a significant linear trend (P < .01) for hypoxanthine‐uric acid, pH, total moisture and intensity of flavor and also a linear trend (P < .05) for juiciness. There was a significant vitamin × position interaction (P < .011 and breed × vitamin × position intertction (P < .011) for hypoxanthine‐uric acid. Cooked loin steaks from Charolais‐Hereford crossbred heifers had slightly higher apparent IMP and hypoxanthine‐uric acid values than steaks from Hereford straightbred carcasses. Average flavor desirability scores were slightly higher for Hereford straightbred heifers than for the Charolais‐Hereford crossbreds, although the differences were not found statistically significant. Total moisture and average juiciness sensory scores were significantly different (respectively P < .01 and P < .05) among loin steak positions. Size and location of muscle within the carcass, cooling rate, pH of tissue, inter‐and intramuscular fat, and lean muscle mass are some factors believed to affect nucleotide degradation and content of hypoxanthine‐uric acid.

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