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 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.

II RESUMO O efeito da temperatura e o efeito do enriquecimento do piso de gaiola sobre o bem-estar de coelhos em crescimento foram avaliados. Quarenta e oito coelhos do grupo genético Botucatu, desmamados aos 35 dias de idade

Inadequate pre-slaughter handling conditions can compromise animal welfare and productivity. This study aimed to evaluate the animal welfare (AW) indexes during pre-slaughter handling and quantify the carcass lesions of beef cattle submitted to different loading densities. A total of 270 Nellore cattle, at 30 months of age, from three farms were used in the study. Each farm presented a different loading density: higher density (500kg/m2), intermediate density (450kg/m2), and lower density (420kg/m2). Three shipments of cattle from each farm with 30 animals each were used in the AW analysis. Ten animals from each shipment were considered for quantification of carcass bruises. The AW indexes were classified according to the five-freedom criterion (physiological, environmental, sanitary, behavioral, and psychological). After slaughter, the carcasses were inspected in the routine line and evaluated for the presence of lesions. Statistically significant differences (p<0.001) were found for all variables studied as a function of AW and bruises. The best AW index and the lowest mean weight of lesions were found at the loading density of 450kg/m2. The highest carcass weight was observed at the loading density of 500kg/m2. Lesions were found in 100% of the animals at the loading densities of 500 and 420kg/m2. In conclusion, the best AW indexes and the smallest occurrence of bruises were verified at the loading density of 450kg/m2. This study confirmed the importance of adequate pre-slaughter handling to ensure cattle welfare and, consequently, greater profitability for producers and slaughterhouses.

Exposure to ochratoxin A (OTA) can lead to changes in global gene expression. This study investigated the individual expression of genes turned on and off in renal cells of chicks after different durations of exposure to dietary OTA. One hundred and eighty day-old male broiler chicks (Ross 308) were randomly assigned to a 3 × 3 factorial arrangement of treatments (3 levels of OTA: 0, 1 and 2 mg OTA/kg diet and 3 time periods: 7, 14 and 21 d). Birds were allocated to 36 pens (4 replicate pens of 5 birds each per treatment). For RNA-Sequencing analysis (RNA-Seq), kidney samples were collected weekly from 3 controls and 3 chicks fed 1 mg OTA/kg. Birds fed 2 mg OTA/kg diet were not chosen for analysis because their reduced feed intake could affect gene expression. The libraries were constructed by Illumina's TruSeq RNA protocol. NextGENe software was used for alignment and transcript quantification. Reads per kilobase of target per million tiled reads (RPKM) were used in the Binary test analysis (P < 0.05). The highest RPKM values were used as criterion for the selection of the genes described. A total of 27,638,976 50-bp RNA-Seq reads were produced over the 3 time periods. Transcripts (40,782) were assembled de novo and annotated by homology to either G. gallus or H. sapiens. The genes activated at 7 d were IL9 and TULP1, at 14 d was GHSR and at 21 d were GRK6 and GAPDH. Unlike all other genes, LOC396365 was activated during all time periods. In contrast, the genes deactivated at 7 d were SPAG4 and LOC100857131, at 14 d were LOC771469, NKX2-1, NKX2-8, FOXO1, MyHC and CLDN18 and at 21 d was XPC. The B-G gene was turned off at 7 and 21 d. All of these genes were involved in kidney toxicity. Therefore, the turning on and off responses of these genes may contribute to carcinogenic and tumorigenic effects of OTA in birds.

Consumption of ochratoxin A (OTA) contaminated diets by broilers results in economic losses to the poultry industry. This experiment evaluated the effects of quantity and time of exposure to dietary OTA on performance, organ weights, serum biochemistry, and renal gene expression of chicks. Determination of genes expressed in response to OTA will allow for the identification of pathways that are influenced by OTA. 180-day old male broiler chicks were randomly assigned to a 3×3 factorial arrangement of treatments (3 levels of OTA; 0, 1 and 2 mg OTA/kg diet and 3 time periods; 7, 14 and 21 days) with 4 replicate pens of 5 birds each per treatment. For RNA-sequencing analysis (RNA-Seq), kidney samples were collected weekly from 3 controls and 3 chicks fed 1 mg OTA/kg. NextGENe software was used for read alignment and transcript quantification. Birds fed 2 mg OTA/kg diet had decreased feed intake and body weight gain, and increased serum uric acid on days 14 and 21. Compared to controls, birds fed 2 mg OTA/kg diet also had poorer feed conversion and increased kidney weights. On day 21, birds fed 1 mg OTA/kg diet had decreased albumin, and aspartate aminotransferase concentrations. Genes associated with carbohydrate and amino acid metabolism were downregulated, and genes associated with the immune system were upregulated at days 7 and 14. Genes associated with lipid metabolism and xenobiotic biodegradation were also downregulated on day 14. These changes disappeared on day 21 suggesting that the kidney and other related organs were repaired or the damage was contained. In conclusion, decreased performance and increased kidney weight and serum uric acid in birds fed 2 mg OTA/kg confirmed the effects of OTA. Supplementation of 1 mg OTA/kg diet caused time-dependent alterations in renal gene expression in chicks.

The objective of this study was to evaluate the health status, productive performance and carcass traits of growing rabbits housed in pen with litter and conventional cage. At 35 d, 54 crossbred rabbits (New Zealand White vs. Botucatu) were randomly housed in pen with litter (6 pens, 6 rabbits/pen, 2.3 rabbits/m²) or cage (6 cages, 3 rabbits/cage, 8.3 rabbits/m²) and kept until the age of slaughter at 77 d. To simulate farm conditions, the rabbits that were housed in pen have not been previously adapted to this system. There was greater intensity of dirt and mucus occurrence in the rabbits housed in pens in first period, but the mucus occurrence practically disappeared in the later period. For performance, the rabbits housed in cages had a higher live weight at 56 d (1714 vs. 1506 g; P<0.001), as well as BWG (46.4 vs. 36.7 g/d, P<0.001) and better FC (2.75 vs. 3.33; P<0.05) from 35 to 56 d. However, these animals did not show the best performance (P>0.05) in the posterior period (56 to 77 d). There was no effect (P>0.05) of housing system for carcass yield, dissectible fat and hind leg yield. It may be suggested that rabbits adapt to the floor over time. Therefore, it is indicated the adoption of this system for growing rabbits.