L. J. C. Lara

Effects of lipid sources in the diet of laying hens on the fatty acid profiles of egg yolks

The effects of different dietary lipids on the fatty acid profiles of eggs produced by 20- and 54-wk-old Dekalb laying hens were investigated. The 4 treatments were based on the lipid source added to the diet: soybean oil, sunflower oil, linseed oil, or control (no added oil). The experimental design was a simple random-sample design using a 4 × 2 factorial arrangement (4 treatments and 2 ages). The fatty acid composition of the yolks of eggs produced by the laying hens was analyzed. The fatty acid profiles found in the egg yolks were the same as those provided in each diet. Eggs laid by hens fed the diet containing soybean oil had a large amount of n-6 polyunsaturated fatty acids (PUFA), whereas eggs laid by hens fed the diet containing linseed oil had the highest percentage of n-3 PUFA. A decrease in PUFA deposition in egg yolks was observed as the laying hens got older. Eggs of hens fed the diet containing linseed oil presented an n-6:n-3 ratio of 2.01 in younger chickens and 2.17 in older ones. The trans fat percentages found in the egg yolks of all treatments were very low. It was concluded that the quantity of fatty acids present in the egg yolk may be altered according to the source of lipids in the diets; the addition of linseed oil to the ration of laying hens resulted in the production of n-3-enriched eggs and excellent n-6:n-3 ratios, and the egg yolks had insignificant amounts of trans fat, irrespective of the different lipid sources added to the diets or the age of the chickens.

Qualidade de ovos comerciais submetidos a diferentes condições de armazenamento

Physical-chemical egg qualities of 1440 egg from commercial layer hens of different ages (30 and 60-week-old) submitted to storage under room temperature or refrigeration conditions were evaluated according to the following traits: Haugh Unities (UH); pH of albumen (pH); total solids of albumen and yolk; and weight and percentage of albumen, yolk, and shell. Decrease of inner quality of the evaluated eggs was observed during the experiment, mainly eggs from old-layers, which presented the worst values of AA and HU when stored at room temperature. It was concluded that age, temperature and time of storage of eggs influenced egg quality.

Bioactive amines and internal quality of commercial eggs

The physicochemical and microbiological qualities of commercial eggs produced by layer hens of different ages (approximately 30 and 60 wk old) were submitted to storage under room temperature or refrigeration for 28 d. A total of 600 eggs were subjected to microbiological analyses of their inner contents and another 600 to a determination of Haugh units (HU) and bioactive amine content. A decrease in the quality of the inner contents of the eggs was observed during the experiment, mainly in the eggs from the 60-wk-old layers, which presented the worst HU values when stored at room temperature (P < 0.05). Microbiological analyses showed an absence of Salmonella spp., Staphylococcus aureus, and coliforms, either total or thermal-tolerant; however, low counts of other Staphylococcus species, Enterobacter spp., Pseudomonas spp., mesophilic aerobic bacteria, and fungi were also recorded. The chromatographic analysis of bioactive amines detected the presence of phenylethylamine in all albumens (38.0 mg/kg) and spermidine in the yolks (1.02 mg/kg). It was concluded that the age of the hens and the time and temperature of storage influenced the quality parameters of the eggs (P < 0.05). Furthermore, despite the low levels of microbial contamination found, phenylethylamine was detected in the albumen. It was not possible to establish index of quality of eggs using bioactive amines present in the yolk and albumen of eggs.

Antioxidant properties of vitamins in nutrition of broiler breeders and laying hens

The reaction of free radicals with polyunsaturated fatty acids (PUFAs) initiates a chain-reaction process known as lipid peroxidation in living systems and oxidative rancidity in foods. PUFAs are more susceptible to oxidation, resulting in the formation of toxic products. As embryonic tissues are characterised by high concentration of PUFAs, the use of antioxidants in broiler breeder diets improves chick oxidative status. Eggs ‘in shell’ are considered resistant to oxidative rancidity, however studies showed that yolk lipids within table eggs oxidise during storage and this oxidation is influenced by time and temperature of storage and the degree of unsaturation of yolk fatty acids. Thus, experiments into supplementing laying hen diet with antioxidants have been conducted to preserve the table eggs nutritional value. The literature shows that vitamin E has antioxidant activity in the egg yolk, protecting embryonic tissues efficiently during incubation and in the first days of a chicks life. However, these studies have not considered the effect of this vitamin on incubation yield. Without this economic variable, the positive results observed in the embryo and for chick oxidative status have little value for application in the field, mainly because the concentrations recommended in studies are much higher than those used in practice. Other antioxidants, e.g. canthaxanthin, act in synergy with vitamin E, however, the high cost of these ingredients could prevent its use for broiler breeders. This review discusses the effect of vitamins (especially vitamin E) in broiler breeders and laying hens nutrition on oxidative stability of embryonic tissues and table egg yolk lipids, respectively.

Avaliação da qualidade da casca dos ovos provenientes de matrizes pesadas com diferentes idades

We conducted a study on eggshell quality from Cobb® broiler breeders at different ages by assessing the relationship between eggshell weight and egg weight and analysis of specific weight, thickness, porosity, strength and electron microscopy. Both treatments were defined by broiler breeder age, considering eggs from young breeders (33 weeks) and eggs from old breeders (63 weeks). It was observed that eggs from breeders at 33 weeks have lower weight and number of pores per cm2 compared with eggs from older birds. 63 weeks broiler breeders had lower percentage of eggshell in relation to egg weight, lower specific weight, strength and thickness, when compared with eggs from young breeders. The proportion of shell membranes in relation to its total thickness was significantly higher in young breeders. It was concluded that eggs from older broiler breeders have lower eggshell quality than the young breeders. The shell membranes in young breeders eggs play a significant role in its structure, making it necessary to focus on this layer in future studies on eggshell quality and their relationship between breeder age and incubation yield.

Bioactive amines and microbiological quality in pasteurized and refrigerated liquid whole egg

The objective of this study was to evaluate the correlation between the levels of bioactive amines and the microbiological quality of liquid pasteurized egg stored under refrigeration. Pasteurized whole egg liquid was obtained from 2 types of different raw materials, fresh eggs, and commercial fertile eggs. They were stored under refrigeration over a period of 21 d. The treatments were arranged in a completely randomized split plot, with the plots being the 2 types of liquid pasteurized egg, and the subplots being the 4 storage periods (1, 7, 14, and 21 d). The storage period did not contribute to the increase (P > 0.05) of contamination by mesophilic aerobic microorganisms and total coliforms in commercial liquid pasteurized egg. However, for fertile eggs, the storage period led to an increase (P < 0.05) in the numbers of microorganisms. Levels of the amines putrescine, cadaverine, and tyramine were detected only in fertile liquid pasteurized egg, and the storage period contributed to the increase (P < 0.05) in the levels of these amines. There was a high correlation between total coliform most probable number and cadaverine levels, and a moderate correlation between the numbers of aerobic mesophilic microorganisms and tyramine levels. It was concluded that the most contaminated liquid pasteurized eggs were the fertile liquid pasteurized eggs and this caused the highest levels of bioactive amines in them compared with all the eggs that had been subjected to pasteurization and refrigerated storage.

Suplementação de colina em dietas para frangos de corte machos na fase inicial de criação

The effects of supplemental levels of choline on performance, carcass composition and gross and histopatology characteristics of the livers in the initial phase in diets for broiler chickens were evaluated. The treatments were defined by the levels of choline supplementation (zero, 100, 200, 300 and 400mg choline/kg diet). The period of creation was one to 21 days-old. Diets formulated based on corn, soybean meal and meat meal are constituted by isonutrient except the levels of choline. The experimental design was completely randomized and the estimation of choline supplementation was evaluated by regression models. The levels of choline supplementation showed a significant linear effect for the F test (P 0.05). The supplementation of 400 mg choline/kg diet improves feed conversion of broilers at 21 days old.

Desempenho de frangos de corte alimentados com diferentes níveis de suplementação de vitamina E

This study aimed to evaluate the effect of vitamin E supplementation on the performance of broiler chickens in the initial and growth phase, from one to 21 and 21 to 39 days of age, respectively. Five increasing levels of DL-α tocopherol supplementation (10, 30, 50, 75 and 100mg to each kg of diet) were added to the diet. In the initial phase (experiment I), the lowest vitamin E level was superior by presenting significant effect (P≤0.05) on body weight at 21 days of age and weight gain from one to 21 days old. In the growth phase (experiment II), there was no significant effect (P>0.05) of vitamin E supplementation on the variables studied. The minimum level of vitamin E supplementation tested is sufficient to attend the requirements of male broiler chickens.

Determinação da energia metabolizável e balanço de nitrogênio de dietas com diferentes teores de proteína bruta para frangos de corte

A metabolism trial was carried out in metabolic cages in a completely randomized experimental design to evaluate the effect of CP reduction on nutrients and energy digestibility in the diets of broiler chickens. A hundred sixty male broiler chickens were randomly allotted to four treatments (CP levels) and four replicates of 10 birds each. The crude protein levels used in the diets were 21, 19, 17 and 15. The total excreta was colleted and recorded from 25 to 29 days of age. The CP reduction improved dry matter and energy digestibility linearly. A quadratic effect of the CP level on CP digestibility was observed. The maximum digestibility was estimated for broilers fed 15.3% CP diets. The nitrogen intake and excretion decreased linearly with the CP reduction. The maximum retained nitrogen and nitrogen efficiency utilization were estimated for broilers fed 18.3 and 15.3% CP diets, respectively. No effect of CP levels on ME was observed.

In ovo feeding and its effects on performance of newly-hatched chicks

The broiler chicks gastrointestinal tract undergoes significant morphological and physiological changes during the first days after hatch. These changes occur mostly because birds switch from a diet based on fatty acids from the yolk sac to a diet based on carbohydrates, provided by commercial feeds, often formulated with corn and soya bean meal. In ovo feeding techniques enable the study of the early adaptation of the avian gastrointestinal tract, such as supplementation with carbohydrates during embryonic development. This procedure consists of inoculation into the amniotic fluid through a hole in the egg shell near the air-chamber during late embryonic growth. The hatching process requires large supply of energy to the muscles, and in ovo feeding has the objective of providing extra energy in order to avoid glycogen store reductions, which are needed during the first days after hatch. However, published reports have shown that in ovo manipulation can reduce incubation yield, mostly when applied during the beginning of embryonic development. The best results of in ovo feeding were found when supplementation was with carbohydrates.