Inheritance of carcass variables when giant jungle fowl and broilers achieve a common physiological body weight.

Ten chicks each from Giant Jungle Fowl (JF), broiler breeders (BB), and the respective F1 cross between them, were reared under typical broiler management practices until they reached a market weight of approximately 1,818 g. When individual birds reached market weight they were killed by CO2 asphyxiation and variables (length and weight) associated with organ, muscle, and skeletal growth were measured. Age to market weight demonstrated parental and heterotic effects. The JF had more deboned leg muscle and less Pectoralis major muscle than BB. Abdominal fat was higher in BB and showed positive heterosis. Organ weights were consistently lower for JF than BB. Positive heterosis was observed for spleen and pancreas, and negative heterosis was indicated for heart, liver, and lung. The digestive tract generally weighed less and was shorter in length for JF than for BB. Positive heterosis was observed for proventriculus and gizzard weight, and negative heterosis was noted for duodenum and jejunum lengths. Parental line differences were observed for most bone variables, including weight and length. Parental lines differed for femur breaking strength, but not for tibiotarsus breaking strength. A large negative heterotic effect was observed for tibiotarsus bone breaking strength.

Divergent selection for body weight and yolk precursor in Coturnix coturnix japonica. 9. Evaluation of traits associated with onset of sexual maturity.

An experiment was conducted to compare traits associated with onset of sexual maturity in Japanese quail lines. Lines divergently selected for high and low 4-wk BW (HW and LW), and high and low total plasma phosphorus at beginning of lay (HP and LP) were compared with a randombred line (RBC1) that served as the base population for HW, LW, HP, and LP. The HW sublines (HW-HP and HW-LP) and LP subline (LP-HW) were also compared to their respective line of origin. Most of the differences observed for males selected for a single trait were found for weight-selected rather than for phosphorus-selected lines. The patterns of significance closely followed differences expected due to the extreme diversity in BW for the HW and LW when compared with RBC1. Females generally matured approximately 2 wk later than males for HW, HP, and LP. Line LW females matured approximately 4 wk later than LW males. Differences were observed for variables associated with onset of sexual maturity for HW, LW, and HP when compared with RBC1. Observed changes in carcass variables for sublines were generally associated with reductions in BW for HW-HP, and HW-LP versus HW and for increases in BW for LP-HW versus LP. The differences were likely due to the fact that two-trait selection (BW for males and total plasma phosphorus in females) has allowed weights to diverge when compared with lines selected for single traits.

Effect of a urease inhibitor and ceiling fans on ascites in broilers. 1. Environmental variability and incidence of ascites.

A low ventilation model to induce ascites was introduced and characterized. In addition, the effect of supplemental air mixing via ceiling fans (CF) and the feeding of a urease inhibitor (0, 125, and 250 ppm) on incidence of ascites were investigated. Twelve environmental chambers were utilized in the trial; six were fitted with CF. Each dietary treatment was replicated twice per CF treatment. One hundred and twenty day-old male commercial broilers were reared per chamber. Atmospheric O2, CO2, and NH3, temperature, and humidity, as well as weekly litter moisture and pH, were monitored. Chamber CO2 levels increased immediately then stabilized. Chamber NH3 levels increased between 2 to 4 wk of age and rapidly declined when ventilation rates were increased to 1 cfm per bird. The CF and dietary treatments had little effect on air or litter variables except for NH3. Supplementing the diet with urease inhibitor resulted in a greater than 50% reduction in cumulative mortality due to ascites and a slight reduction in weekly BW gains. The CF treatment had no effect on production variables such as weekly feed intake, gain, and feed to gain ratio, or survivability due to ascites.

Effect of a urease inhibitor and ceiling fans on ascites in broilers. 2. Blood variables, ascites scores, and body and organ weights.

Restricted ventilation was used to experimentally induce ascites in commercial male broilers. The role of a dietary urease inhibitor (0, 125, and 250 ppm) and ceiling fans to reduce ascites was investigated. At 6 wk of age, birds were bled, euthanatized, weighed, scored for ascites, and heart, liver, and small intestine weights were obtained. Random samples were analyzed for intestinal ammonia. Blood samples were analyzed for blood gases, hemoglobin, red blood cell count, blood urea nitrogen, ammonia, and uric acid. Birds fed 125 and 250 ppm urease inhibitor were significantly (P < .001) lighter at 6 wk, when compared with controls. Urease inhibitor (125 and 250 ppm) significantly decreased large intestine ammonia. Urease inhibitor significantly increased small intestine (250 ppm) and liver weights (125 and 250 ppm), whereas urease inhibitor at 125 ppm decreased right ventricular heart weight. Urease inhibitor had no effect on ascites scores, blood gases, or blood ammonia, but hemoglobin, blood urea nitrogen, red blood cell count, and uric acid were significantly (P < .05) decreased by 125 ppm urease inhibitor.