Performance of broilers submitted to high CO2 levels during incubation combined with temperature fluctuations at late post-hatch

Incubation represents around 1/3 of the life cycle of broilers of modern strains; therefore, the appropriate management of this period is crucial to ensure the quality of the neonate. An experiment evaluated the effect of carbon dioxide concentrations during incubation on the live performance, heart morphology, and differential leukocyte count in the blood of broilers submitted to fluctuating temperatures between 35 and 42 days of age. In total, 2,520 fertile eggs were distributed according to a completely randomized design with four CO2 concentrations (4,000; 6,000; 8,000 and 10,000 ppm) during the first ten days of incubation, after which all eggs were incubated at the same CO2 level (4,000 ppm). After hatching, male chicks were placed in the experimental broiler houses, and at 35 days of age, 25 birds from each level of CO2 were separated and placed in cages to study the effect of cyclic temperature variations up to 42 days of age on their live performance, heterophil:lymphocyte ratio, and heart morphology. At 42 days of age, blood was collected for hematology and two birds per replicate were sacrificed and evaluated for ascites score and heart and liver relative weights. Heart morphology was assessed by analyzing digital images. In this experiment, hypercapnia during incubation and fluctuating temperatures during the growout did not affect mortality, ascites score, heart and liver relative weights, or heart characteristics (p&gt;0.05). However, heterophill:lymphocyte ratio increased (p<0.05) with increasing carbon dioxide concentrations during incubation. It was concluded that high CO2 levels during incubation did not influence the resistance of broilers to fluctuating temperatures during the last week of age

Effects of Guanidionoacetic Acid and Arginine Supplementation to Vegetable Diets Fed to Broiler Chickens Subjected to Heat Stress before Slaughter

ABSTRACT The objective of this study was to evaluate the supplementation of guanidinoacetic acid (GAA) and L-arginine (L-Arg) as creatine precursors to vegetable diets on the carcass yield and meat quality of broilers subjected to two days of heat stress before slaughter. A total of 1260 broiler chicks were distributed according to a completely randomized design into four treatments with nine replicates of 35 birds each. The treatments consisted of: T1 - vegetable diet based on corn and soybean meal (control diet); T2 - control diet with the inclusion of meat meal (3%); T3 - control diet supplemented with GAA (0.08%); and T4 - control diet supplemented with L-Arg (0.8%). The birds were submitted to heat stress for two days before slaughter (from 42 to 44 days of age). The birds fed the diets supplemented with GAA or L-Arg presented heavier carcasses (p<0.0035), higher breast yield (p=0.0685), and lower of abdominal fat deposition (p=0.0508) than those fed the control diet and the control diet with meat meal. The cooking loss of the breast fillets of broilers fed the control diet supplemented with meat meal, GAA or L-Arg was lower (p<0.0068) compared with those fed the control diet. Thawing and pressure-driven breast fillet weight losses, and pH, luminosity, redness (a*value), and yellowness (b* value) values were not influenced by the treatments. When GAA is less expensive than commercially-available Arg, the dietary supplementation of GAA is more advantageous, based on the meat yield improvements observed in the present study