Avian Biology Research

With the growing awareness among the general public, the demand for food products rich in omega-3 polyunsaturated fatty acids (n-3 PUFA) has increased over the years. Hen eggs enriched with n-3 PUFA are serving this purpose. Several earlier trials indicated that the addition of n-3 PUFA-enriched feed stuffs in laying hen rations readily promoted the n-3 PUFA contents of egg yolks. A major increase was noticed for linolenic acid content in the egg yolk and also for long chain n-3 PUFA. The egg cholesterol was also decreased to some extent by feeding n-3 PUFA-enriched diets to laying hens. However, the production performance and egg characteristics have been questioned in some of the studies conducted on n-3 PUFA feeding to laying hens. The major problem mentioned was a decrease in the egg weight and egg-yolk weight. It is suggested that more consideration should be given to the performance and egg characteristics in future studies on feeding n-3 PUFA to laying hens.

This study was carried out to examine histological and enzyme histochemical characteristics of the oesophageal tonsil in ducks (Anas platyrhynchos). Tissue samples were collected from distal parts of the mucosal folds at the oesophageal/proventricular junction. We applied alpha naphthyl acetate esterase and acid phosphatase to tissue sections for localisation of T or B lymphocytes. Trichrome staining, silver impregnation, methyl green-pyronin staining and PAS reaction were used for determination of light microscopic structure of the oesophageal tonsils. The oesophageal tonsils were located at the junction of the oesophagus and proventriculus. Interestingly, we detected the existence of high endothelial venules in the interfollicular area and of the accumulated positive cells in lymphoid nodules. It can be said that these tonsils have functions similar to the Harderian gland in avian species and Waldeyer's ring in mammalian species.

The morphology of the small intestine was investigated in Muscovy ducklings before and after the hatching period using light micoscopy. The villi, crypt depth, villi: crypt (V:C) ratio, were measured in embryos on days 24 and 30 of development, on the day of hatching, and in neonates on days 2, 9 and 13 post-hatching. The height, width and perimeter (girth of villi) of small intestinal villi significantly increased with age (P < 0.05). Villi number (per transverse section of small intestine) decrease from 2 to 13 days post-hatching (P < 0.05). The crypt depth and width were significantly affected by age from hatching to 2 days of age (P < 0.05). The number of crypts increased significantly in the duodenum and jejunum between hatching and 9 days of age (P < 0.05). In the duodenum and jejunum, the V:C ratio peaked at hatching, and decreased from hatching to 2 days of age (P < 0.05). The parameters of villi and crypt of the small intestine rapidly changed between hatching and 9 days post hatch suggesting that the first week of life is a crucial step in physiological changes.

This study performed a histological and morphometric investigation of testes in Gallus gallus x Phasianus colchicus hybrids during the seasonal reproductive period of pheasants. The trial was conducted on seven 4-year old birds originated from the mating between New Hampshire cocks and female common pheasants. After sacrifice, testes were removed, macroscopically evaluated and routinely processed for light microscopic investigations. Mean testis weight was 0.85 g and a great variability was observed between birds. Only one bird out of seven developed heavier testes each weighing almost 3g. Relative volume occupied by seminiferous tubules was 75%. Approximately 39m of seminiferous tubules were found per testis and around 96 m per gram of testis. A high correlation was observed between the number of Sertoli cells and germ cells with testis weight. Seminiferous epithelium comprised Sertoli cells and germ cells at different stages of development. Three birds presented tubules with a multilayered epithelium and germ cells developed until the stage of round spermatids. Surprisingly, one bird presented some elongated forms as well.

In this experiment the effects of total dietary phosphorus (TP) and calcium (Ca) on growth, feed conversion ratio, breast muscle yield, serum phosphorus (P), and bone measurements were examined. From 3 to 6 weeks, four levels of TP (4.5, 5.0, 5.5, and 6.0g kg⁻¹) and two levels of Ca (7.0 and 9.0g kg⁻¹) provided eight treatments. From 6 to 7 weeks, diets with two levels of TP (4.5 and 5.5g kg⁻¹) and three levels of Ca (6.0, 7.0, and 8.0g kg⁻¹) were used. Diets with 4.5g kg⁻¹ TP did not contain a source of inorganic P. Interactions were detected for feed intake, weight gain, and serum P at 6 weeks. Birds fed 5.0, 5.5, and 6.0g kg⁻¹ TP with 9.0g kg⁻¹ Ca consumed more feed and gained more weight as compared to the other groups. Feed conversion of birds fed the 9.0g kg⁻¹ Ca diet was lower than those fed diets with 7.0g kg⁻¹ Ca. Serum P was increased (P < 0.05) at the lowest level of TP when dietary Ca was lowered. Lowering the Ca level, in general, raised (P < 0.05) serum P. Ash was a function of the amounts of TP and Ca in the diets; Ca and P contents of the bones were not affected by the dietary treatments (P > 0.05). Interactions or main effects for TP and Ca were not detected for body weight gain, feed consumption, feed conversion, breast muscle yield, serum P and bone measurements at 7 weeks of age. Our findings demonstrate that from 3 to 6 weeks of age, dietary total P can be lowered to 5.0-5.5 g kg⁻¹ while the inorganic P source can be removed in the finisher diets without loss in performance or bone integrity.

An established method for evaluation of skeletal anomalies was successfully adapted to Japanese quail (Coturnix coturnix japonica) and performed on 793 untreated 1-day old chicks to develop an historical control database. Incomplete ossification of the pelvic bones and irregular position of the toes were rather frequently observed. Subsequently, 702 chicks from the treatment groups in three one-generation reproduction studies with the pesticides dimethoate, triphenyltin (fentin) hydroxide, and vinclozolin were compared to their respective controls and the whole historical database. Presumed treatment-related effects were confined to a higher number of chicks with incomplete ossification of vertebrae and pelvis when the hens had been administered fentin hydroxide at a dietary level of 30 ppm for up to 6 weeks, corresponding to a mean daily substance intake of 3.1-3.9 mg kg⁻¹ body weight (bw). Thus, inclusion of teratological findings as a further endpoint confirmed the previously established NOAEL of 3 ppm (equal to 0.28-0.35 mg kg⁻¹ bw/day) based on reproductive effects in this study. No effects on skeletal development were seen with dimethoate and vinclozolin up to the highest dietary concentrations of 70 and 500 ppm, corresponding to estimated mean daily intakes of about 8 or 56 mg kg⁻¹ bw. The suitability of the method for reliable detection of skeletal anomalies was proven. The established method can be considered useful in providing additional information for ecotoxicological risk assessment.

We studied the reproductive biology of the White-rumped Swallow (Tachycineta leucorrhoa) in a colony of 50 nests boxes located in a wetland of the Paraná River, Santa Fe, Argentina between 2004 and 2006. The nest boxes were checked regularly and reproductive parameters, as well as morphological data of eggs and nestlings, were recorded. The species had an average clutch size of 4.7 eggs whose volumes and weight means were 2.04 cm³ and 2.17 g. respectively. The incubation period averaged 15.9 days and decreased with the clutch size. The mean nestling period was 23.8 days. Clutch size, number of nestlings per nest and the nestling period decreased with the advance of the breeding seasons, while the incubation time increased. Breeding parameters showed a similarity with those reported for the population from Chascomús site, although the eggs were 5% heavier, the incubation period took one more day and the reproductive success was also higher. With the closely related species Tachycineta meyeni, the studied species showed a lower clutch size. Finally, considering another closely related species Tachycineta bicolor, the White-rumped Swallow showed the reproductive life history traits characteristic of species in the southern hemisphere. We provide new information for this species nesting on wetlands, a fact that contributes to the understanding of changes in the life history of the Tachycineta genus along the American continent.