-The experiment evaluated the influence of isolated or associated phytogenic additives (PA) and organic acids (OA) on nutrient digestibility, performance and carcass characteristics of broiler chickens. Two experiments were conducted in a completely randomized design with a 2 × 2 + 1 factorial arrangement of treatments (with or without PA × with or without OA + antibiotic performance enhancer and anticoccidial). In the first experiment, two metabolic tests were conducted to determine the metabolizability coefficients of the nutrients of starter and growth diets. In the second experiment, 2520 one-day-old chicks were housed in 40 experimental units to evaluate the performance and carcass characteristics. The phytogenic additives and organic acids, isolated or associated, improve the nutrient digestibility of the diet and replace the growth-promoting antibiotics. The use of organic acids isolated or associated with phytogenic additives in broiler diets improves broiler performance in comparison with free antibiotic performance enhancer at 42 days of age. Isolated or associated phytogenic additives and organic acids provided better carcass characteristics.

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2 × 3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature × diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 3 3 factorial arrangement (two genetic groups and three ambient temperatures: 188C, 258C and 308C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.48C and 63.9%, 24.48C and 80.2% and 29.68C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 308C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group 3 ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.

The effect of feed restriction and enzymatic supplementation on intestinal and pancreatic enzyme activities and weight gain was studied in broiler chickens. Quantitative feed restriction was applied to chickens from 7 to 14 d of age. An enzyme complex mainly consisting of protease and amylase was added to the chicken ration from hatching to the end of the experiment. Birds subjected to feed restriction whose diet was not supplemented showed an increase in sucrase, amylase, and lipase activities immediately after the restriction period. Amylase, lipase, and chymotrypsin activities were higher in chickens subjected to feed restriction and fed a supplemented diet than in those only subjected to feed restriction. Trypsin activity increased after feed restriction and after supplementation, but there was no interaction between these effects. Early feed restriction had no effect on enzyme activity in 42-d-old chickens. Chickens subjected to early restriction and fed the supplemented diet presented higher sucrase, maltase, and lipase activities than nonsupplemented ones (P < 0.05). There was no effect of early feed restriction or diet supplementation on weight gain to 42 d. Percentage weight gain from 14 to 42 d of age was equivalent in feed-restricted and ad libitum fed birds. Feed-restricted broilers fed a supplemented diet showed a higher percentage weight gain than nonsupplemented birds. We conclude that enzymatic supplementation potentiates the effect of feed restriction on digestive enzyme activity and on weight gain.

Aiming at evaluating the influence of cyclic temperatures on the performance and egg quality of Japanese quails an experiment was carried out with 480 birds after egg production peak. Birds were housed in a bioclimatic chamber with automatic temperature control that contained two rooms, one maintained at thermoneutral temperature (21 ºC) and the other adjusted for the tested cyclic temperatures (24, 27, 30, 33 and 36 ºC at a time). Each room had a battery of five floors and ten cages, with a capacity of 24 birds per cage, totaling 240 birds per battery. Birds were fed iso-nutritious and iso-caloric diets. Data obtained under the tested cyclic temperatures were compared with those obtained under thermoneutral temperature. At the end of each experimental period (14 days) performance and egg quality parameters were evaluated. A completely randomized experimental design with two treatments (thermoneutral temperature and tested temperature) and ten replicates of 24 birds each. Cyclic increases of 27 ºC and higher in environmental temperature negatively affected bird performance, with reduced feed intake and consequent reductions in egg weight and mass. A cyclic increase of the environmental temperature to 36 ºC reduced the percentage of saleable eggs and egg production

This present study aimed at evaluating the effect of the addition of an emulsifier to diets containing soybean oil, poultry fat or their blend, on the performance, carcass traits, serum lipid levels, pancreatic lipase concentration and nutrient digestibility of broilers. A randomized block design was applied using a 3 x 2 factorial arrangement, with three fat sources (soybean oil, poultry fat, and a blend of 50% soybean oil and 50% poultry fat) and the addition or not of an emulsifier. In experiment I, broiler performance, carcass traits, serum cholesterol, HDL, and triglyceride levels, and pancreatic lipase activity in 42-day-old broilers were evaluated. In experiment II, dry matter (DM), ether extract (EE), crude protein (CP) and crude fiber (CF) coefficients of digestibility were analyzed. Broilers fed the diet containing soybean oil and emulsifier presented higher body weight, weight gain and better feed conversion ratio. When birds were fed poultry fat and the fat blend (soybean oil and poultry fat) and the emulsifier was added to the diets, pancreatic lipase concentration increased. It was concluded that the use of soybean oil, poultry fat and their blend does no in the diet does not influence the performance, carcass traits, or serum cholesterol, HDL and triglyceride levels of 42-day-old broilers. The addition of emulsifiers to diets containing poultry fat improves ether extract digestibility and increases the production and secretion of pancreatic lipase

Bovine meat and bone meal (MBM) was widely used in animal diets until outbreaks of Bovine Spongiform Encefalopathy (BSE) occurred in some countries. It has not been confirmed yet whether or not BSE may be transmitted to man through chicken meat originated from poultry that had been fed diets containing MBM. Therefore, consumers nowadays express preference for meat originated from birds fed exclusively vegetable diets. This study analyzed samples of major breast muscle (Pectoralis major) using mass spectrometry of stable isotopes (carbon and nitrogen) as a means to assess the presence of MBM in broiler diets, a technique that might be used in the certification of poultry quality. A total of 150 day-old chicks were reared in five randomized treatments with increasing MBM dietary inclusion levels (0, 1, 2, 4 and 8%). On day 42, breast muscle samples were collected from three birds per treatment and used in the determination of

The objective of this study was to evaluate the effects of the interaction between genetic group (Botucatu or crossbred) and ambient temperature (thermoneutral, moderate or intense heat stress) on physiological indicators and performance of growing rabbits. Ninety-six weaned rabbits were used, half from the Botucatu genetic group and half crossbreds (New Zealand White males× Botucatu females). They were assigned to a completely randomized design in a 2× 3 factorial arrangement (two genetic groups and three ambient temperatures) with repeated measures (weeks). Colonic temperature, skin surface temperature, ear surface temperature, and respiratory rate were recorded from 42 to 67 days of age, whereas body weight and feed intake were recorded from 35 to 70 days of age. Average ambient temperature and relative humidity in the environmental chambers were 18.4°C and 63.9% (thermoneutral), 24.4°C and 80.2% (moderate heat stress) and 29.6°C and 75.9% (intense heat stress). Mean colonic temperatures ranged from 39.4 to 39.7°C across treatments. Botucatu rabbits showed higher (Pb 0.05) skin surface temperature under moderate heat stress than the crossbreds (33.0±0.1 vs. 32.6±0.1°C, respectively) and higher (Pb 0.01) respiratory rates independently of ambient temperature (161.4±2.8 vs. 148.1±2.8 breaths/min, respectively) than the crossbreds. Skin surface temperature, ear surface temperature and respiratory rate were positively related to ambient temperature. Under intense heat, average daily gain of Botucatu rabbits was higher (Pb 0.05) than that of the crossbreds (33.72±0.90 vs. 30.66±0.96 g/day, respectively), but there was no difference with thermoneutral or moderate heat conditions. This finding characterizes a genotype× environment interaction. When the age effect was considered, an increase in colonic temperature under intense heat was detected over the last week. Respiratory rate increased in both genetic groups from six to eight weeks of age, but the increase was more pronounced in Botucatu rabbits than in crossbreds, and the difference between groups was consistently amplified over weeks. Intense heat severely depressed average daily gain as age advanced, especially beyond week eight. As expected, feed consumption increased during the experimental period, but the rate was inversely proportional to ambient temperature. Under intense heat stress, feed consumption of Botucatu rabbits was slightly, but consistently, higher than that of the crossbreds as age advanced. Relevant differences in physiological responses and growth performance between rabbit genetic groups under heat stress were detected.