Aml Ribeiro

Granulometria do Milho em Rações de Crescimento de Frangos de Corte e seu Efeito no Desempenho e Metabolismo

Two experiments were carried out to evaluate corn particle size, expressed by the average geometric diameter (AGD), .0.337; 0.574; 0.680; 0.778; 0.868 e 0.936mm on performance, energetic metabolism and intestinal morphology (villi height and crypts depth of duodenum) of 21 to 42 day-old male broilers. In the first experiment, particle size of 0.868 mm showed greater feed intake and weight gain and better feed conversion. Villi height was not affected by the AGD of the diets, but increased with the broilers age (21, 35 and 42 days of age). Abdominal fat deposition was not affected neither the proportion of carcass cuts. Gizzard weight was positively related with particle size. In the second experiment, feed with particle size of 0.337 mm led to a lower energy intake and greater gross energy excretion. Nitrogen retention was not affected by particle size.

Fatty-acid composition of free-choice starter broiler diets.

Two experiments were carried out to evaluate the inclusion of vegetable oils with different fatty acid content in starter and pre-starter broiler diets. In Experiment I 480 1- to 9-day-old male Ross 308 broilers were fed diets containing corn oil (CO), acid corn oil (ACO), linseed oil (LO) or coconut fat (CoF). Chicks were distributed according to a factorial 2x2x2arrangement (2 free fatty acids - FFA ) x (2 n6:n3 ratios) x (2 medium-chain fatty acids levels - AGMC). Performance responses and dry matter (DMM), crude protein (CPM), and crude fat (CFM) metabolizability were evaluated. In Experiment II, 480 1- to 20-day-old male Ross 308 broilers were offered the free choice of 2 different diets: with no fat addition, or with 10% addition of the following fat sources: CO, LO, CoF, soybean soapstock (SBS), acid soybean oil (ASO), or acid cottonseed oil (ACtO). Performance responses and diet selection were evaluated. In experiment I, there were no significant effects of the diets on performance, DMM, or CPM; however, the inclusion of FFA depressed CFM. In experiment II, there was a marked preference of birds of the diets with fat inclusion, leading to the selection of diets with more than 3100 kcal/kg ME in the period of 1 to 20 days, independently of fat source. The broilers selected the high fat and energy diets since the first days of age, which resulted in better bird performance.

Effect of vitamin E levels on the cell-mediated immunity of broilers vaccinated against coccidiosis

Studies on the relationships between animal nutrition and immunity have sought reliable methodologies to measure responses. Cellmediated immune response is similarly studied in humans. The cutaneous basophil hypersensitivity test (CBH) is one of the methods to measure that response and consists in the infiltration of inflammatory cells, particularly of lymphocytes and basophils, as result of the application of substances capable of inducing cell proliferation in determined sites, such as wings, wattle, and interdigital space in birds. CBH is considered a simple and fast method and can be applied in birds of different ages. In immunocompetence studies with poultry, phytohemagglutinin-P (PHA-P) is a commonly used substance, despite the variability of the response related to the method of application (intradermal injection) and the antigens used. In the present experiment, PHA-P was used to observe the cell-mediated immune response of 216 chicks fed three dietary levels of vitamin E from 1 to 36 days of age. All birds were immunologically challenged by vaccination against coccidiosis at three days of age and against Newcastle Disease (NCD) at 14 and 30 days of age. At 36 days of age, birds were submitted to the CBH test according to the methodology of Corrier & DeLoach (1990). Birds fed 65mg/kg of vitamin E presented lasting cell reaction (p £0.08), which indicates that this vitamin E level improved cell immune response of birds due to its antioxidant and immunomodulating properties. The use of this vitamin E level can be considered by nutritionists under practical conditions, aiming to improve broiler immunity.

Effect of Dietary Fiber and Genetic Strain on the Performance and Energy Balance of Broiler Chickens

The experiment was conducted to evaluate the effect of dietary fiber on the performance and energy balance of broiler chickens of a fast-growing strain (Cobb500) and a slow-growing strain (Label Rokens during the period of 1 one to 42 days of used In total, 360 male broilers (240 fast-grorain and 120 slow-grtrain)were, housed in collective cages. A completely randomized experimental dewith in a 3x2 factorial arrangement was applied, consisting of three groups of birds (slow-growing - SG; fast-growing fed ad libitum - FGAL; and fast-growing pair-fed with SG broilers - FGPF) and two iso-protein dis (a 3100 kcal ME/kg low-fiber diet and a 2800 kcal ME/kg high-fiber diet- Hwith containing 14% wheat bran and 4% oat hulls). Dietary fiber level did not affect feed intake (FI); however, it resulted in lower weight gain (WG) and worse feed conversion ratio (FCR) (p < 0.001) in birds fed the HFD diet due to its lower energy content. The FGPF group presented higher WG than SG and better FCR (p < 0.001), indicating that fast-growing birds present better performance than SG broilers, even under restricted feed intake. The SG group retained more energy relative to body weight (p < 0.001), which is associated to higher body fat retention in this strain (p < 0.001). The slow-growing strain did not present better use of high-fiber diet than fast-growing strain as expected.

Determination of apparent metabolizable energy of crude glycerin in broilers chickens.

The objective of the experiment was to determine the Apparent Metabolizable Energy corrected for nitrogen (AMEn) of a glycerin product derived from biodiesel production for broilers. A number of 35 male Ross 308 broilers, with 35 days of age was fed ad libitum diets containing 0, 5, 10, 15, or 20% glycerin. AMEn was determined using total excreta collection, with four days of adaptation and three days of collection. Increasing glycerin intakes resulted in increased water excretion. Glycerin AMEn varied as a function of dietary inclusion levels, and a cubic equation was identified by regression analysis. Maximum AMEn level- 4890 kcal/kg DM- was obtained with 15% glycerin inclusion. However, this level caused excessive water excretion, making its use unpractical.

Effect of chick weight, geometric mean diameter and sodium level in prestarter diets (1 to 7 days) on broiler perfomance up to 21 days of age

Seven hundred and twenty Ross 308 chicks were raised in a controlled environment room, distributed in a factorial design with 3 hatching chick weights (37, 40 and 44 g), 3 geometric mean diameter (GMD) (0.561; 0.783 and 0.997 mm) and 4 total sodium levels (Na) (0.12; 0.24; 0.36 and 0.48%) in the pre-starter diet (1 to 7 days). From 8 to 21 days (d) one single basal diet was used for all treatments. The thirty seven-gram chicks had the smallest yolk sack weight at 4d, smallest body weight (BW) and feed intake (FI) at 7d and 21d, but the same feed conversion (FC) than the other groups of hatching weight. Chicks receiving diet with intermediate GMD had the greatest BW and FI at 7d, but at 21d this effect was no longer seen. The diet with finest particle size resulted in birds with the smallest gizzard weight at 7d. The 0.12%Na diet was statistically different from the other Na levels, resulting in chicks at 7d with the worst FC and lowest body weights. At 21d, BW still was the lowest for this group of chicks. Birds with 0.48%Na produced more watery excreta and less dry matter in the carcass at 7d. Water consumption (C H2O ) was influenced linearly by chick weight up to 0.36%Na level. In the 0.48%Na level, 40 and 44 g chicks had similar C H2O , which was different from 37-g chicks. For best performance, Na values were set from 0.31 to 0.48%. The three studied factors influenced quality of pre-starter diet and consequently chick performance.

Effect of dietary fiber, genetic strain and age on the digestive metabolism of broiler chickens

In this study, 360 male broilers, out of which 240 of a fast-growing strain (Cobb500), and 120 of a slow-growing strain (Label Rouge), were used to evaluate the effect of dietary fiber on digesta transit time and digestive metabolism during the period of 1 to 42 days of age. A completely randomized experimental design with a 3x2 factorial arrangement was applied, consisting of three groups of birds (slow-growing – SG; fast-growing fed ad libitum – FGAL; and fast-growing pair-fed with SG broilers – FGPF) and two iso-protein diets (a 3100 kcal ME/kg low-fiber diet –LFD- and a 2800 kcal ME/ kg high-fiber diet –HFD- with 14% wheat bran and 4% oat hulls). HFD-fed birds presented lower ME retention (p < 0.001) and lower dry matter metabolizability (DMM) (p < 0.001), which is possibly related to the shorter digesta transit time observed in these birds (p < 0.001). DMM was reduced with age, whereas metabolizable energy remained almost constant (p < 0.001) independently of strain. This may be related to the increase in feed intake as birds age. The slowgrowing strain did not present better utilization of the high-fiber diet as compared to the fast-growing strain in none of the analyzed ages, even though showing a significant better use of fiber and dietary energy from 31 days of age.

Compensatory water consumption of broilers submitted to water restriction from 1 to 21 days of age

A hundred and fifty male Ross 308 broilers were submitted to water restriction (WR) in different levels (0 to 40%) until 21 days of age. The birds received water ad libitum from 22 to 28 days of age and the compensatory consumption of water (CConW) was calculated as the difference in water intake between birds submitted and not submitted to WR. All WR groups showed a compensatory consumption of water, mainly during the first days of the ad libitum period. The water intake in such groups decreased as the birds adapted to the new condition. Higher water intake was observed in birds with 30 and 40% WR than in birds with 10% WR. Furthermore, chickens showed an unusual drinking and feeding behavior during the restriction period.

Effect of Different Dietary Concentrations of Amino Acids on the Performance of Two Different Broiler Strains

Four Nutritional Programs (NP) used in the Brazilian poultry industry were tested in two broiler strains (Cobb 500 and Ross 308). NP varied in the concentrations of their main essential amino acids (AA) and were classified as Low, Regular, High and Mixed (high AA concentrations up to 21 days and regular concentrations after that). Minimum digestible Met+Cys/Lys, Thr/Lys, Arg/Lys, Ile/Lys, and Val/Lys ratios were 0.74, 0.64, 1.05, 0.65 and 0.75, respectively, in all NP, and no minimum amount of CP was fixed. There were no interactions between strain and NP for any of the evaluated responses. From 1 to 47 days of age, birds fed the Low NP presented lower average body weight and body weight gain (BWG). The high NP allowed for better feed conversion ratio (FCR), followed by the Regular and the Mixed NP. Ross 308 broilers were heavier, presenting worse FCR due to higher FI. Birds fed the High NP had lower carcass yield than those fed the Low NP. The Low and Regular NP had lower costs per WG when compared with the High NP. Low and Regular NP presented higher gross margin returns compared with the High NP. The Regular and Mixed NP are the most recommended, presenting intermediate performance and higher economic returns.

Effects of the Addition of Pure Glycerin Supplementation in the Drinking Water on the Performance of Broilers Submitted to Heat Stress and Feed Restriction

The experiment was conducted to study the effect of pure glycerin supplementation (GLYC) in the drinking water of broilers subjected to heat stress and feed restriction. Water with 0, 1, or 2% glycerin was provided ad libitum to broilers in six hours of feed restriction. The birds were housed in two environments: thermoneutral (TN) - 25 ° C, and cyclic heat stress (HS) - 12h with 250C, 6h with 320C, 3h of 250 to 320C and 3h of 320 to 250C. The experimental design was randomized in a factorial arrangement of 2 x 3 + 2, with three GLYC levels, two environments and one control group with ad libitum feeding each environment. When submitted to HS, broiler receiving 2% glycerin presented higher weight gain (WG), water consumption (WC), feed intake (FI) and energy consumption (EI) than those in the other treatments, contrarily to birds in TN, where increasing GLYC levels decreased those responses. Broilers submitted to feed restriction presented reduced FI, but better feed conversion (FCR), independently of rearing environment or GLYC levels. Broilers under HS submitted to feed restriction and receiving 2% GLYC presented higher WC (p< 0.05) and similar WG as the controls, differently from the restricted-fed broilers under TN receiving 2% GLYC, which WC and WG were lower than the controls. The inclusion of 2% pure glycerin in the drinking water may compensate the negative effects on performance caused by feed restriction in broilers submitted to heat stress.