ABSTRACT The objective of this study was to evaluate the performance and carcass yield of broilers submitted to heat stress during different rearing stages. A total of 840 one-day-old CobbAvian48TM male broilers were housed in an experimental house equipped with conventional ventilation system and foggers. Birds were distributed according to a completely randomized design into four treatments, with six replicates of 35 birds each. The treatments consisted of: T1 (control) - birds reared under natural temperature and relative humidity conditions from 1 to 42 days of age; T2 - birds submitted to heat stress (HS) from 16 to 21 days of age; T3 - birds submitted to HS from 22 to 42 days of age; and T4 - birds submitted to HS from 16 to 42 days of age. Birds were submitted to heat stress daily for one hour (12:00-13:00h).On day 42, performance data were determined. Six birds per replicate were selected and sacrificed to obtain carcass, parts, and giblet weights and yields. Performance parameters were not influenced by the treatments. Broilers submitted to 1-h cyclic heat between 16 and 42 days of age presented lower deboned breast weight compared with those maintained in natural temperature and relative humidity conditions. It was concluded that the performance of broilers submitted to short cyclic heat periods is not impaired.

ABSTRACT The objective of this study was to evaluate the effect of using exoenzyme phytase in broiler's diets on digestibility of nutrients, feed energy and tibia bone mineralization. A completely randomized design was used, with the following treatments: sorghum with dicalcium phosphate (SDP), corn with dicalcium phosphate (CDP), sorghum with meat and bone meal (SMBM), sorghum with valued phytase (SVP) and sorghum with phytase without valued (SPWV). For digestibility analysis, eighty 15 day old broilers were used, a total of 1400 male Hubbard Flex chickens, which were submitted to total excreta collection to obtain the percentages of food digestibility, crude protein, ether extract, apparent metabolizable energy, calcium and phosphorus while for tibias mineralization. Six birds per treatment were used, where determination of mineral matter, calcium and phosphorus were performed. Metabolizable energy (ME) and apparent metabolizable energy corrected for nitrogen (AMEn) of the feed were also calculated. Data were subjected to variation analysis and the average compared by 5% Tukey test. There was no difference between treatments for the digestibility at 15-20 day old as well as for the feed energy values, but the diets with phytase had higher phosphorous percentage values for tibia bone mineralization, demonstrating that exogenous phytase enzyme is able to hydrolyze phytate origininated from plant and release the phosphorus for assimilation by animals, acting as a substitute for phosphorus plant sources.

ABSTRACT The objective of the study was to evaluate the effect of nutritional plans on the productive and economic performance of Hubbard Flex broiler chickens. A completely randomized experimental design was applied, consisting of five treatments. Treatments consisted of five different nutritional plans: a basal diet containing the nutrient and energy levels recommended by literature and designated reference diet; two diets containing 1.5% and 3% lower levels than the reference diet; and two diets containing 1.5% and 3% higher levels than the reference diet (-3%, -1.5%, reference plan, +1.5% and +3%). Feed intake (FI), body weight (BW), feed conversion rate (FCR), livability (L) and productive efficient index (PEI) were determined when broilers were 42 days old. Broilers were processed, and carcass and parts (breast fillet, leg, and wings) yields were determined. The economic viablility of the nutitional plans was evaluated as a function of feed cost/kg live and carcass weights, economic efficiency index (EEI), and cost index (CI). Feed intake and the feed conversion rate decreased as dietary nutrient and energy levels increased. Feed cost/kg live weight, economic efficiency index, and cost index cost increased as dietary nutrient and energy levels increased. Feed intake, feed conversion ratio, production efficiency index, and breast yield improved with increasing nutritional and energy levels. However, worse economic results were obtained with higher nutritional and energy levels.

ABSTRACT This study aimed at evaluating the replacement of inorganic copper, manganese, and zinc sources by organic sources in the diet of laying hens during the second laying cycle in trace mineral excretion, egg production, and eggshell quality. Two hundred and fifty 100-week-old Dekalb hens were distributed according to a completely randomized design into five treatments with five replicates of ten birds each. The control treatment consisted of a basal diet with all trace minerals in the inorganic form. The other treatments consisted of a basal diet with a mixture of the minerals copper, manganese, and zinc in the organic form with concentrations of 100%, 90%, 80%, and 70% of the levels of inclusion of inorganic mineral sources in the control treatment. Trace mineral excretion was determined in five layers per treatment by the method of total excreta collection. Excreta trace mineral contents were determined by atomic absorption spectrophotometry. Egg production and eggshell quality were determined by the mass of the eggs and the egg specific gravity, respectively. For all trace minerals examined, the dietary supplementation with organic sources reduced trace mineral excretion compared with the control group, even at 70% inclusion level, without compromising egg production or eggshell quality. The replacement of the inorganic trace mineral sources by organics source effectively reduced the excretion of copper, manganese, and zinc by laying hens in the second laying cycle.

This study aimed at evaluating the effects of whole and ground sorghum, compared with ground corn, on the live weight, feed conversion ratio, organs weight and intestinal biometrics and histomorphometrics. In total, 960 Hubbard Flex broilers were reared until 42-day-old and distributed into 24 pens, according to the three treatments: ground corn, whole-grain sorghum, and ground sorghum. On day 42, five male birds per treatment were selected by similar body weight and sacrificed. Gizzard absolute weight, and proventriculus, liver, pancreas and heart relative weights, and duodenum, jejunum, ileum, ceca, and colon length and relative weight were determined. Villus characteristics and intestinal mucosa absorption surface area were evaluated. Broilers fed sorghum, independently of physical form, were heavier and had greater feed conversion ratio than those fed ground corn. Gizzard showed the highest relative weight in broilers fed whole sorghum compared to corn. Liver and jejunum relative weight was higher in broilers fed ground corn, compared to ground sorghum. Whole small intestine, cecum and colon relative lengths showed no difference among treatments. Deeper crypts were found in the duodenum of broilers fed whole grain sorghum, compared to ground sorghum, as well as in jejunum compared to ground corn; however, intestinal absorption surface area was not different among treatments. Whole or ground grain sorghum may replace corn in the feed of 1- to 42-d-old broilers, since they improve body weight and feed conversion ratio, and not adversely affect intestinal morphometry and organs weight.

The objective of the present study was to evaluate the supply of a specific-male diet on rooster body weight, hatchability, and fertility. Two diets were supplied during the egg production period: treatment 1, diet formulated for females and containing, in average, 2,830 kcal ME/kg and 15% CP; and treatment 2, diet specifically formulated for male broiler breeders, containing 2,750 kcal ME/kg and 13.5% CP. In the experiment, 26 flocks, with approximately 7,000 females and 840 males each, belonging to the same broiler breeder commercial strain, were distributed into 26 houses (1200m²) on the same farm, and submitted to the same management practices. Body weight was evaluated in 13 flocks per treatment and for five weeks (45, 50, 55, 60, 65), and hatchability and fertility in four incubation lots per treatment and for the same weeks. Data were evaluated by the analysis of mixed models for repeated measurements, using the PROC MIXED of SAS 9.3 (SAS Institute Inc., Cary, NC, USA), and means were compared by the test of Tukey-Kramer at 5% significance level. The specific-male diet allowed body weight control during all analyzed weeks and promoted high hatchability and egg fertility. The increase in the number of chicks hatched demonstrates the economic viability of feeding a specific diet for male broiler breeders.

The objective of this study was to evaluate the performance and carcass characteristics of broilers fed exclusively vegetable diets and diets containing animal meal with the addition of creatine or not after day 8. In the experiment, 1080 one-day-old male chicks were distributed according to a completely randomized experimental design into six treatments with six replicates each. A control diet based on corn and soybean meal was formulated, to which animal meals and creatine were included or not. Diets were formulated to contain equal mineral (calcium, phosphorus and sodium) and amino acid (available methionine + cystine, lysine and threonine) levels. The following treatments were applied: A. control (diet based on corn and soybean meal); B. control + creatine (600g/ton); C. inclusion of 5% meat and bone meal (MBM), D. inclusion of 5% MBM + creatine (600g/ton), E. inclusion of 5% blood meal (BM), F. inclusion 5% BM + creatine (600g/ton). Weight gain, feed intake, feed conversion, carcass yield and viability were evaluated. At 42 days of age, BM dietary inclusion impaired weight gain and feed conversion ratio. The inclusion of MBM affected only feed conversion ratio. The addition of creatine ito the diet with BM improved weight gain when compared with the BM diet with no creatine. The addition of creatine to the diet containing 5% BM improved weight gain when compared with the same diet without the use of the additive.