Maturation and ovulation of Japanese quail oocytes under in vitro conditions

1. An in vitro system for ovulation and maturation of Japanese quail oocytes is described.

2. Ovarian follicles removed from the ovary at 2, 4 or 6 h before the estimated time of ovulation may ovulate under in vitro conditions.

3. The presence of progesterone in the medium had a stimulatory effect on the process of maturation, as has been shown for Xenopus oocytes.     

Foetal development in quail during the final stages of incubation

Fertile eggs of the bobwhite and Japanese quail were opened and examined during the last 4 days before hatching and the foetal position and stage of development recorded at known times after the beginning of incubation. A comparison is made between these stages in the quail and similar stages in the domestic fowl.     

Study of the submicroscopic structure of striated muscles in Japanese quail under conditions of stress

An electronmicroscopic study of striated muscles was made in Japanese quail stressed by hypokinesis. During 15-day hypokinesis influencing m. gastrocnemius, small pale vacuoles were found out on some mitochondria. The process of alterations went on, and in the 15-day hypokinetic animals, alterations in myofibrils were observed besides the alterations in mitochondria. They manifested themselves by indistinct lines of actin and myosin fibers and by an uneven course of Z-lines. The alterations of m. gastrocnemius mitochondria in Japanese quail during hypokinesis were probably caused by energy insufficiency and subsequent hydration of the organella. Nearly all components of the muscular tissue were impaired by the 30-day hypokinesis.     

Traits influencing the hatching performance of Japanese quail eggs

1. Japanese quail eggs from moderately heavier sires showed superior fertility; while fertile eggs from moderately heavier dams hatched slightly better than the eggs from lighter dams.

2. Higher rates of fertility and hatchability of Japanese quail eggs were observed from parents of 10 to 19 weeks of age, with peak fertility and hatchability at 14 and 12 weeks of age, respectively.

3. Sex ratios of 1:2 to 1:5 gave comparable fertility and hatchability results.

4. The hatching performance of quail eggs from cage and deep litter reared breeders was comparable.

5. Fertility and hatchability were directly proportional to the egg weight.

6. Quail egg shell colour, tints and blotches were found to influence hatching performance.

7. Storing quail eggs at 16 ± 2°C and 75 ± 5% relative humidity for more than 4 d reduced hatchability.

8. Hatchability of eggs stored at room temperature was improved if they were sealed in polyethylene bags.

9. Provision of light during the first 14 d of incubation resulted in a photo‐acceleration of about 3.2 h.     

Adaptability of Japanese quail chicks to conditions of simulated weightlessness

The objective of this study was to evaluate the adaptability of young Japanese quail chicks to the simulated weightlessness, represented by hypodynamy. Unsexed hatchlings were subjected to hypodynamy on either the first, second or third day of age and reared under these conditions to 21 days of age. During this period, the control quail chicks were housed in a floor box. The effect of hypodynamy on adaptability of chicks was significant (P < 0.001). Approximately 75% of all chicks exposed to hypodynamy were not able to adapt in three experimental groups, although significant differences in adaptability were not found between these groups. Those birds were considered as non-adapted (eliminated from experiment) that manifested hyperactivity, escape attempts, turning 180 degrees in the sling, soaking in the water from the drinker, as well as the total apathy, at least three times per day. This experiment confirmed that some quail chicks are capable of adapting to conditions simulating weightlessness to 21 days of age and that the first 2-weeks after hatching may be a critical period of quail sensitivity to hypodynamy. This finding raises a key issue relevant to rearing quails in simulated weightlessness until the age of sexual maturity.     

Effect of cooling Holstein cows during the dry period on postpartum performance under heat stress conditions

Two experiments were completed to determine whether cooling Holstein cows during their 60-day prepartum period improved their immediate physiological status as well as subsequent postpartum performance. In Experiment 1, 38 cows were divided into two pens that were not cooled, or where the cows were moved twice daily to be cooled by soaking until their body was completely wet. Prepartum respiration rate (RR) and rectal temperatures (RT) did not differ between groups, indicating that the cooling system was largely ineffective, which was consistent with differences that only numerically favored the treated group in postpartum productive (milk production, milk fat content and related response variables), and reproductive (services per conception and days open) performance. In Experiment 2, 52 Holstein cows were used over 3 years (n = 24 in year one; n = 12 in year two; n = 16 in year three) and cows were housed in pens either not cooled or cooled with water spray and fans. Cooled cows had lower RR and RT prepartum at 14:00 and 18:00 h vs. non-cooled cows, indicating that the cooling system was effective, and this was consistent with improved productive (milk production, milk fat content and related response variables), and reproductive (services per conception and days open) performance postpartum. In addition, there was a trend (P = 0.10) to higher birth weights of calves from cooled mothers (which was consistent with a numeric difference in Experiment 1). Use of effective cooling systems under hot and dry conditions during the dry period can improve postpartum productive and reproductive performance of Holstein cows.     

Influence of thermal stimulation during the late phase of incubation on hatching results and post-hatch broiler performance under commercial conditions

1. Two experiments, which differed in breeder age, strain and season, were conducted to study the influence of low-intensity, short-duration thermal stimuli during the late phase of incubation on hatchability and performance. The first experiment conducted in April–June used eggs from Cobb × Ross broiler breeders at 35–41 weeks of age and the second experiment performed in February–April used eggs from Hubbard × Cobb broiler breeders at 49–53 weeks of age.

2. Eggs in the test group had the same physical environment as eggs in the control group except that incubation temperature was increased by 1?C for 2 h/d above the control group from 18 to 20 d of incubation (DI).

3. The results demonstrated that thermal stimulation of 1?C for 2 h/d above control incubation temperature during 18–21DI did not have any adverse effects on hatch and post-hatch performance of broilers.

4. In both experiments, treatment did not significantly alter the secondary sex ratio in hatched chickens, but hatch residue showed that the proportion of unhatched male embryos was significantly lower in the test groups than in the control groups.

5. In the first experiment, thermal stimulation improved feed conversion by 1.82% compared with the control.

     

Influence of varying dietary electrolyte balance on broiler performance under tropical summer conditions

A 6‐week feeding trial was conducted to determine the effects of varying dietary electrolyte balance (DEB) on growth performance and physiological responses in broiler chicks reared during hot summer months (26.1–37.5 °C). The average minimum and maximum room temperatures recorded from 14 to 42 days of age were 26.1 and 37.5 °C, respectively, with relative humidity ranging from 51% to 55%. Five DEB treatments supplying 0, 50, 150, 250 and 350 (Na⁺+K⁺–Cl^?) mEq/kg of diet were prepared by adding NaHCO₃ and/or NH₄Cl to basal diet that contained 185 mEq/kg from 1 to 28 days and 172 mEq/kg from 29 to 42 days. These DEB diets were randomly offered to six experimental units of 20 chicks each. Improved 42‐day body weight gain (BWG), feed:gain (F:G) and reduced mortality was noted with DEB 50, 150 and 250 mEq/kg compared to DEB 0 and 350 mEq/kg. A quadratic effect of increasing DEB level was observed on BWG and F:G, whereas the effect was linear for feed intake, water intake and litter moisture. The DEB 50, 150 and 250 maintained better blood pH, pCO₂ and HCO₃ concentrations during acute heat stress periods than that of 0 and 350. The blood heterophil and lymphocyte percent as well as heterophil:lymphocyte were remained unaffected. The lowest DEB (0 mEq/kg) diet reduced the feed intake and promoted metabolic acidosis. At 350 mEq/kg DEB, water intake and metabolic alkalosis were promoted probably due to high levels of dietary NaHCO₃. The study concluded that overall better performance was recorded with DEB 50, 150 and 250 mEq/kg. These results indicated that single optimal DEB value could not be recommended to combat heat stress in broilers.     

Effect of clinoptilolite on performance of Japanese quail (Coturnix coturnix japonica) during experimental aflatoxicosis

Clinoptilolite (CLI, a natural zeolite), incorporated into the diet at 50 g/kg, was evaluated for its ability to reduce the deleterious effects of 2.0 mg total aflatoxin (AF;83.06% AFB1, 12.98% AFB2, 2.84% AFG1 and 1.12% AFG2)/kg diet on growing Japanese quail chicks from 10 to 45 d of age. A total of 40 Japanese quail chicks were divided into 4 treatment groups (control, AF, CLI, AF plus CLI) each consisting of 10 chicks. The performance of the birds was evaluated. The AF treatment significantly decreased food consumption and body weight gain from the 3rd week onwards. The adverse effect of AF on food conversion ratio was also significant from week 4 of the experiment. The addition of CLI to an AF-containing diet significantly reduced the deleterious effects of AF on food consumption, body weight gain and food conversion ratio. Food consumption was reduced by 14% in quail chicks consuming the AF diet without CLI, but by only 6% for quail chicks consuming the AF plus CLI diet. Similarly, overall body weight gain was reduced by 27% in birds consuming the AF diet without CLI, but by only 8% for birds consuming the AF plus CLI diet. The addition of CLI to the AF-free diet significantly decreased food consumption and body weight gain during week 4, but these parameters were similar to the controls in week 5. No mortality was observed in any of the groups. These results suggest that CLI effectively diminished the detrimental effects of AF on the variables investigated in this study.     

Effects of photoperiod during incubation on embryonic and post-embryonic development of quail and chickens

The effect of light during incubation on embryonic and post‐embryonic development of White Leghorn chickens and Northern Bobwhite quail was determined. The treatments were: (a) 12 h light followed by 12 h dark (12L—12D), (b) 24 h light (24L—0D) and (c) 24 h dark (0L—24D) per day throughout incubation.

The development of the embryos of both species was accelerated by increasing the length of exposure to light during incubation. There were no differences in hatchability, weight at hatching, or at 4, 8, 12, 16 or 20 weeks of age. The incidence of healed navels was increased with greater length of exposure to light during incubation. No differences in egg production due to treatment were detected.     

Brooding temperatures for chicks acclimated to heat during incubation: effects on post-hatch intestinal development and body weight under heat stress

1.?The objective was to evaluate the effects of brooding temperature on intestinal development, oxidative organ damage, and performance of chicks acclimated to high temperature during incubation. The effects of acclimation and brooding temperatures on slaughter weights of broilers under heat stress were also investigated.

2.?Eggs were incubated at either 37?8°C (INC_Cont) or heat-acclimated at 39?5°C for 6 h daily from d 10 to d 18 of incubation (INC_H). Brooding temperatures at floor level were set at 32, 33?5 and 35°C (Bt₃₂, Bt_33?5, Bt₃₅, respectively) for the first 5 d. The temperature was reduced gradually to 30°C from d 6 to d 10. From 21 to 42 d, broilers from INC_Cont Bt₃₂ and INC_H Bt₃₂ and Bt₃₅ were divided into two groups; half from each group was exposed to daily cyclic higher ambient temperatures, while the other half was reared at control temperature.

3.?INC_H chicks had lower jejunum, but greater liver and residual yolk sac weights than INC_Cont chicks on the day of hatching. Although INC_H chicks from Bt_33?5 and Bt₃₅ had lighter body weights than Bt₃₂ on d 5, no significant differences were observed in the body weight of broilers among treatments at 10 and 21 d.

4.?Similar jejunum protein, alkaline phosphatase, maltase, glutathione, and malondialdehyde contents of chicks from INC_Cont and INC_H suggested that heat acclimation during incubation has no effect on jejunum enzyme activity or oxidative status of chicks.

5.?Taking into account INC_H Bt₃₅ chicks having lower T₃ levels on d 5, lower heterophil/lymphocyte (H/L) ratios and similar weights at 42 d under heat stress compared with control broilers, the results suggested that although higher brooding temperatures had no effect on body weights of INC_H chicks during the brooding period, those broilers may able to cope better with heat stress.     

Ontogeny of copulatory behaviour in male Japanese quail classified by their T-maze performance as hatchlings

1. This study examines the time courses of male mating behaviours using quail that were categorised at 2 d of age as high performance (HP) or low performance (LP) individuals in a T-maze. 2. Individually caged males from each T-maze category were observed for 5 min after a female of the same category (HP or LP) was introduced into their home cages as a sexual partner at 4, 5, 6, 8, 10 and 12 weeks of age. The number of grabs, mounts and cloacal contacts performed by each male and his copulatory efficiency (number of cloacal contacts/number of grabs; CE) were determined at each time interval. 3. No differences were observed in the proportion of HP and LP males performing grabs at any of the ages evaluated. However, a greater proportion of HP males showed mounting and cloacal contact behaviour, coupled with a higher CE than did their LP counterparts at 5 and 6, 6 and 8, and 8 weeks of age, respectively. At those ages, a higher mean number of mounts and cloacal contacts were also observed. No significant sexual behaviour differences between HP and LP quail were observed at 10 and 12 weeks of age. 4. The results suggest that rapid negotiation of the T-maze in hatchlings is associated with accelerated puberty in male quail. The differential reproductive behaviour of HP males during the development of puberty does not remain extant in fully developed quail. 5. The finding of accelerated male developmental sexual activity responses in HP quail indicates that selection for T-maze HP behaviour may allow males to be successfully bred at an earlier age.     

Genetic properties of egg quality traits and their correlations with performance traits in Japanese quail

1. Performance traits were measured on 1908 Japanese quail and egg quality traits assessed on 1800 eggs at 10?wk of age.

2. Genetic and phenotypic correlations were estimated using a bivariate animal model with restricted maximum likelihood using ASREML software.

3. Body weight at different ages showed positive genetic correlations with egg weight and most of the internal egg quality traits, whereas their genetic correlations with eggshell thickness, eggshell strength and eggshell percentage were negative.

4. Genetic correlations of age at sexual maturity and egg number with most of external and internal traits were negative.

5. It was concluded that selection for higher body weight will result in heavier and better quality eggs. Because of the negative genetic correlation between BW and egg shell quality, a selection index including BW and eggshell strength would be the best breeding strategy for genetic improvement of egg quality in Japanese quail.     

Carcase characteristics of a heavy Japanese quail line under introgression with the roux gene

1. The roux plumage sex-linked recessive gene may be used for early sexing of Japanese quail in crossbreeding production systems with wild-type and roux lines. However, associated effects of the gene on carcase and meat composition need to be assessed. 2. Quail carcases from pure Line K males and females (100% K), a heavy meat line which was used as the recipient line for the introgression of the roux gene, and from same-age roux or wild-type females from the second generation of introgression (75% K) were dissected. The effects of sex, line and plumage colour on carcase components and on protein and lipid contents of various tissues were estimated. 3. Expected sex differences in carcase weights were obtained, with marginally higher values for females. However, weights of parts and carcase yield (ratio of empty carcase weight without head, neck and feet over live body weight) were similar for both sexes in pure Line K which had a 68% carcase yield. Lipid contents in leg meat were higher in males (3.1%) than in females (2.7%). 4. The roux gene did not seem to have any major impact on carcase parts or composition. However, in roux birds, leg skin was marginally higher in lipids and pectoralis major lower in proteins than in wild-type ones.     

Early embryonic administration of xenoestrogens alters vasotocin system and male sexual behavior of the Japanese quail

The copulatory behavior and the parvocellular vasotocin (VT) system of the nucleus of the stria terminalis (BST) are sexually dimorphic in the Japanese quail. Embryonic administration of estradiol benzoate (EB) induces an organizational effect determining the disappearance of such a dimorphism (male shows behavior and cerebral phenotype of the female). The VT parvocellular system can therefore be considered an accurate marker of the sexual differentiation of brain circuits and a very sensitive indicator of the activity of estrogen-like substances on neural circuits. To test this hypothesis we administered diethylstilbestrol (DES), a powerful synthetic xenoestrogen, genistein (GEN), a phytoestrogen produced by soy, and bisphenol A (BPA). After 3 days of incubation, quail eggs were injected with vehicle, EB, DES, GEN or BPA. Administration of BPA caused an early blockage of development and no further analyses were done on the BPA groups. At puberty, the copulatory behavior of EB- or DES-treated male quail was totally abolished, whereas only the highest doses of GEN determined a significant decrease of the behavior. After the tests, the animals were sacrificed and perfused. The fractional area (FA) covered by VT immunoreactivity was analyzed in BST, medial preoptic nucleus, and lateral septum by computerized image analysis. The FA was significantly reduced after treatment with EB, DES and GEN at high doses. These results confirm that the sexually dimorphic VT system of the Japanese quail is a sensible indicator of the effects of xenoestrogens at the level of the central nervous system.     

The effects of different iodide availabilities on thyroid function during development in Japanese quail

Japanese quail (Coturnix japonica) were used to study the effects of different egg iodide (I) availabilities on thyroid function during development. Low (less than 50 micrograms 1/kg feed in the maternal diet) and high (1200 micrograms 1/kg feed) I availability were compared to control levels (800 micrograms 1/kg feed), a standard supplementation for game bird feed. We measured thyroid gland content of I, triiodothyronine (T3) and thyroxine (T4), plasma concentrations of T3 and T4, hepatic 5' monodeiodinase (5'-D) activity, and the response of the thyroid gland to thyrotrophin (TSH) stimulation. Embryos, on day 14 of the 16.5-17 day incubation period, and 1-day chicks were used for most studies but thyroid gland hormone content and plasma hormone concentrations were determined for more stages. With high I, thyroidal I content was elevated but thyroidal T4 and T3 were not different from controls. Plasma T3 and T4, the thyroid gland response to TSH stimulation, and hepatic 5'-D activity did not differ between control and high I. Reduced body weight occurred with high I. In general, thyroid gland weight was not altered, but some high I birds exhibited thyroid hypertrophy and altered thyroid gland function. With low I availability, thyroid gland contents of I and T4 were reduced but thyroidal T3 content was maintained. The thyroid gland response to TSH stimulation, plasma thyroid hormone concentrations, and the developmental patterns of plasma thyroid hormones, hepatic 5'-D activity, body weight and thyroid weight were not different between control and low I groups. Developing Japanese quail exhibit excellent ability to adjust thyroid function over a wide range of I availabilities. Regulation appears to occur at the level of thyroid hormone synthesis in the thyroid gland, which allows most aspects of thyroid dynamics to remain unchanged in the maintenance of circulating thyroid hormone concentrations.     

Increased lipid peroxidation occurs during development in Japanese quail (Coturnix japonica) embryos

1. The growth of the avian embryo is paralleled by an exponential increase in the rate of whole-embryonic oxygen consumption, which potentially increases oxidative damage.

2. Age-related patterns of tissue lipid peroxidation were characterised in brain, liver and heart tissue of developing Japanese quail (Coturnix japonica) embryos between 9 and 15 d of age, over which embryo mass increased by a factor of 6. Lipid peroxidation was quantified in each tissue by spectrophotometric measurement of malondialdehyde using the thiobarbituric acid reactive substances assay.

3. In all tissues, lipid peroxidation increased greatly as development proceeded. Concentrations of malondialdehyde increased in parallel with the cumulative amount of oxygen consumed by the developing embryo consistent with the hypothesis that oxidative stress results from the production of free radicals due to oxidative metabolism.

4. This study describes in vivo oxidative stress in developing avian embryos and suggests that rates of embryonic growth, oxidative metabolism and oxidative damage likely vary in parallel.

     

Physiological responses and performance of Nili-Ravi buffalo calves under different washing frequency during hot summer months in tropics

The effect of washing frequency on the physiological responses and performance of buffalo calves was studied in hot summer. Thirty Nili-Ravi calves aged 4–6 months were divided into three uniform groups of ten. The calves of group A, B and C were washed two (9 a.m. and 3 p.m.), three (8 a.m., 12 noon and 4 p.m.) and four (8 a.m., 11 a.m., 2 p.m. and 5 p.m.) times in a day, respectively. They were washed with water for 5 min at a stretch. The mean linear body measurements, body weight, dry matter intake through concentrate, green fodder and physiological responses, i.e. rectal temperature, pulse rate and respiration rate before and after washing under different daily washing frequency were recorded fortnightly. The average daily gain was also calculated. The mean total dry matter intake was increased with the increase frequency of washing. The maximum mean daily body weight gain was recorded in group C followed by group B and A. There were statistically significant (P < 0.05) differences between the three washing groups. Calves were more comfortable with increase number of washing in a day in hot summer. The rectal temperature, pulse rate and respiration rate also varied significantly (P < 0.05) between the three experiment groups. It can be concluded that daily four times washing in hot summer had more beneficial effects over three and two times washing of young Nili-Ravi buffalo calves to decrease rectal temperature, pulse rate and respiration rate and to increase average feed utilization and daily gain under tropical climate.