Mature Breeder Research Articles

ОСОБЕННОСТИ НЕРЕСТОВЫХ МИГРАЦИЙ ПРОХОДНЫХ ВИДОВ РЫБ КАСПИЙСКОГО МОРЯ ЧЕРЕЗ МОРСКОЙ СУДОХОДНЫЙ КАНАЛ ЗА ПЕРИОД 2001–2022 ГГ.

Background. Anadromous species of sturgeons, salmonids and clupeids inhabiting the Caspian Sea migrate to their spawning grounds predominantly through the Volga-Caspian Sea Shipping Canal (VCSSC), which hydrological and hydrographic features have an effect on the abundance dynamics of the anadromous fish species. Along the entire delta sea edge, the Volga-Caspian Sea Shipping Canal (around 200 km in length) provides the conditions required for fish migration. Relevance. The current decrease in the Caspian Sea level and extensive accumulation of the fluvial and marine drift sediments impede navigation due to insufficient depth of the waterway and affect the entering of the anadromous breeders. This work is aimed at the assessment of the VCSSC use by sheefish, black-spined herring, beluga sturgeon, Russian sturgeon and stellate sturgeon during various seasons within 2001–2022 time range. Methods. Trawling and net fishing have been conducted in the marine part of the canal. Based on the data from seine catches in the river, the seasonal dynamics of fish migrations has been identified. Results. Despite the existence of extensive riverine network of the River Volga Delta suitable for the entering of anadromous fish species (Kirovsky, Belinsky, Igolkinsky, Karaysky and other banks), the Volga-Caspian Sea Shipping Canal (Main Bank) provides the anadromous fish species with a primary transit waterway to their spawning grounds—up to 90 % sheefish and black-backed herring breeders out of the total spawning stock abundance. The share of stellate sturgeon migrating along this waterway is 76–78 %, for the Russian sturgeon it is 83–85 %, and for beluga sturgeon it is 90–95 % of the spawning populations in the year of their entering into the Volga River. In recent years, the ecosystem of the Volga River has been developing in the context of low water content, which leads to the decrease in the water level of fish passage channels and tj a weakened flow, which, exacerbated by abiotic factors, in turn results in the reduction in the spawning stock abundance and decline in the yield of juveniles of the anadromous fish species [1]. Conclusion. During their pre-spawning season, sturgeons, sheefish and anadromous herring use the Volga-Caspian Sea Shipping Canal as the main migratory passageway to their spawning grounds. After the spawning, the canal provides juveniles and mature breeders with the passageways to the feeding sites in the Northern Caspian Sea. Sturgeon juveniles and the individuals skipping the spawning actively feed in the marine part of the canal [2].

Evaluation of morphological indicators of the first mature sturgeon females from eggs in artificial conditions

Sturgeon species of fish are a unique branch of the relict fish fauna. Species biodiversity, features of biology, a wide range, nutritional value, all taken together, made it possible to distinguish this group of fish in an independent direction-sturgeon breeding. In the last century, Russia accounted for up to 90% of the world’s stocks of these fish species. According to the number and species composition of sturgeon, the Caspian basin occupied a dominant position. Nevertheless, over the past 15-20 years, there has been a landslide undermining of the unique stocks of sturgeon fish in this reservoir. The main reason for the reduction of sturgeon stocks is the excess of the removal of populations over their replenishment. Against this unfavorable background, it became necessary to form broodstock in order to compensate for the decreasing number of wild breeders. To solve this problem, two main directions have been formed in sturgeon breeding – the domestication of wild fish and the cultivation of mature breeders in artificial conditions on the principle of “from eggs to eggs”. In the article, fish-biological and physiological indices of the first mature females of beluga grown in the natural background annual dynamics of water-medium temperature by the principle “from eggs to eggs”.

Phenotypic variability and population structure analysis of Tanzanian free-range local chickens

BackgroundFree-range local chickens (FRLC) farming is an important activity in Tanzania, however, they have not been well-characterized. This study aimed to phenotypically characterize three Tanzanian FRLCs and to determine their population structure. A total of 389 mature breeder chickens (324 females and 65 males) from three popular Tanzanian FRLC ecotypes (Kuchi, Morogoro-medium and Ching’wekwe) were used for the phenotypic characterization. Progenies of these chickens were utilized to assess population structure. The ecotypes were collected from four geographical zones across Tanzania: Lake, Central, Northern and Coastal zones. Body weights and linear measurements were obtained from the mature breeders, including body, neck, shanks, wingspan, chest girth, and shank girth. Descriptive statistics were utilized to characterize the chickens. Correlations between the linear measurements and differences among the means of measured linear traits between ecotypes and between sexes were assessed. A total of 1399 progeny chicks were genotyped using a chicken 600 K high density single nucleotide polymorphism (SNP) panel for determination of population structure.ResultsThe means for most traits were significantly higher in Kuchi relative to Ching’wekwe and Morogoro-medium. However, shank length and shank girth were similar between Kuchi and Morogoro-medium females. All traits were correlated with the exception of shank girth in Morogoro-medium. Admixture analyses revealed that Morogoro-medium and Ching’wekwe clustered together as one population, separate from Kuchi.ConclusionsPhenotypic traits could be used to characterize FRLCs, however, there were variations in traits among individuals within ecotypes; therefore, complementary genomic methods should be considered to improve the characterization for selective breeding.

Alternative rib bone biopsy measurements to estimate changes in skeletal mineral reserves in cattle

Rib bone biopsy samples are often used to estimate changes in skeletal mineral reserves in cattle but differences in sampling procedures and the bone measurements reported often make interpretation and comparisons among experiments difficult. ‘Full-core’ rib bone biopsy samples, which included the external cortical bone, internal cortical bone and trabecular bone (CBext, CBint and Trab, respectively), were obtained from cattle known to be in phosphorus (P) adequate (Padeq) or severely P-deficient (Pdefic) status. Experiments 1 and 2 examined growing steers and Experiment 3 mature breeder cows. The thickness of cortical bone, specific gravity (SG), and the amount and concentration of ash and P per unit fresh bone volume, differed among CBext, CBint and Trab bone. P concentration (mg/cc) was closely correlated with both SG and ash concentrations (pooled data, r=0.99). Thickness of external cortical bone (CBText) was correlated with full-core P concentration (FC-Pconc) (pooled data, r=0.87). However, an index, the amount of P in CBext per unit surface area of CBext (PSACB; mg P/mm2), was more closely correlated with the FC-Pconc (pooled data, FC-Pconc=37.0+146×PSACB; n=42, r=0.94, RSD=7.7). Results for measured or estimated FC-Pconc in 10 published studies with cattle in various physiological states and expected to be Padeq or in various degrees of Pdefic status were collated and the ranges of FC-Pconc indicative of P adequacy and P deficiency for various classes of cattle were evaluated. FC-Pconc was generally in the range 130 to 170 and 100 to 120 mg/cc fresh bone in Padeq mature cows and young growing cattle, respectively. In conclusion, the FC-Pconc could be estimated accurately from biopsy samples of CBext. This allows comparisons between studies where full-core or only CBext biopsy samples of rib bone have been obtained to estimate changes in the skeletal P status of cattle and facilitates evaluation of the P status of cattle.

Bone mineral density in the tail-bones of cattle: effect of dietary phosphorus status, liveweight, age and physiological status

In three grazing experiments in the seasonally dry tropics of Australia, growing steers (Experiment 1), first-calf cows (Experiment 2) and mature breeder cows (Experiment 3), ingested diets for 12–17 months, which were either adequate or severely deficient in phosphorus (P) (Padeq and Pdefic, respectively). Bone mineral density (BMD) at the proximal end of the ninth coccygeal vertebra (Cy9) was measured at intervals using single photon absorptiometry (SPA). Liveweight (LW) and plasma inorganic phosphorus (PIP) concentrations were monitored at intervals and rib-bone cortical bone thickness (CBT) of biopsy samples was measured at the end of Experiments 1 and 3. Measurements of LW change, PIP concentrations and CBT confirmed that diet P intakes of cattle in the Padeq treatments were adequate whereas there was severe and chronic P deficiency in the Pdefic treatments. In Experiment 1 BMD in Padeq steers increased with LW and age from ~0.25–0.27 g/cc (8 months, 200 kg LW) to ~0.34 g/cc (32 months, 490 kg LW), whereas in Pdefic steers BMD decreased progressively to ~0.23–0.24 g/cc. Although BMD decreased in the Pdefic steers bone volume of Cy9 (calculated from tail-bone thickness) increased, and some net bone deposition in the Cy9 continued. Rib-bone CBT and tail-bone BMD at the end of Experiment 1 were closely correlated (r = 0.93). In Experiment 2 BMD was initially 0.33 g/cc (~25 months, 400 kg LW) and did not change through pregnancy and lactation in Padeq cows. However, in the Pdefic cows there was a gradual decline in BMD to ~0.25 g/cc. There was no change in dimensions of the Cy9 so the decreases in BMD involved net demineralisation of bone. In Experiment 3 BMD was less responsive to P deficiency than in Experiments 1 and 2. Only after ~11 months was BMD reduced (P < 0.05) in the Pdefic cows, and then only by 15%. In contrast, rib-bone CBT decreased by 30% due to P deficiency, and BMD was poorly correlated with CBT (r = 0.4). The effects of animal weight, age and maturity on tailbone BMD of P-adequate animals, and the different responses to P deficiency observed in young growing steers, first-calf cows and mature breeders are discussed in relation to the use of SPA measured tail-bone BMD to diagnose P deficiency in grazing cattle.

Vitamin E and selenium in broiler breeder diets: Effect on live performance, hatching process, and chick quality

This study evaluated the effect of different dietary vitamin E levels and different selenium sources on the productive and reproductive performance of broiler breeders. In total 640 females and 64 males between 22 and 52 weeks old were studied. A completely randomized experimental design in factorial arrangement, with 4 treatments of 8 replicates with 20 females and 2 males each, was applied. Treatments consisted of 2 vitamin E levels (30 and 120 mg/kg) and two selenium sources (sodium selenite and zinc-L-selenomethionine). Egg production (rate of lay and eggs per breeder), egg characteristics (egg, yolk, eggshell, and albumen weights), fertility, incubation responses (egg weight loss during incubation, hatchability, and hatching window), and hatchling characteristics (weight and yield) were evaluated. There was no influence of dietary vitamin E levels or selenium sources on egg production (P > 0.05). Mature breeders (47 weeks old) fed zinc-L-selenomethionine and 120 mg vitamin E/kg feed produced heavier eggs and albumen. Hatchability of the eggs of breeders fed 120 mg vitamin E/kg feed was higher than breeders fed 30 mg vitamin at 29 wks. The dietary inclusion of organic selenium also promoted heavier hatchling weight until egg production peak (33 wk), but did not influence hatchling quality or hatching window. It was concluded that the dietary supplementation of zinc-L-selenomethione and vitamin E (120 mg/kg feed) could be used to improve egg characteristics and incubation response.

Comparison of growth performance and genetic diversity of pearl oyster (Pinctada martensii) families in a breeding program

In May of 2009, 28 full-sib families were established by selecting mature breeders in the third generation selected line. Growth performances of the families were compared on the basis of shell height and shell length at juvenile and adult stages. Four families were randomly sampled from the 28 families and their genetic variation was evaluated by using seven microsatellite markers. Significant differences in mean shell length and height among the families were observed at days 110 and 320. A total of 23 alleles were detected at seven microsatellite loci in the four families and the number of the alleles at each locus ranged from 2 to 4, with an average of 3.3. The average observed (Ho) and expected (He) heterozygosity of the four families varied from 0.476 to 0.573 and from 0.584 to 0.679, respectively. The results of the analysis of molecular variance (AMOVA) indicated that 88.4% of the total variations was attributed to the genetic variations within family, whereas only 11.6% variations among families. The results that there exists highly genetic diversity and genetic differentiation among the four families indicates desirable conditions for developing superior lines of the species by family mating. Key words: Pinctada martensii, families, growth performance, genetic variation.

What determines hatchling weight: breeder age or incubated egg weight?

Two experiments were carried out to determine which factor influences weight at hatch of broiler chicks: breeder age or incubated egg weight. In Experiment 1, 2340 eggs produced by 29- and 55-week-old Ross® broiler breeders were incubated. The eggs selected for incubation weighed one standard deviation below and above average egg weight. In Experiment 2, 2160 eggs weighing 62 g produced by breeders of both ages were incubated. In both experiments, 50 additional eggs within the weight interval determined for each breeder age were weighed, broken, and their components were separated and weighed. At hatch, hatchlings were sexed and weighed, determining the average initial weight of the progeny of each breeder age. Data were analyzed using the Analyst program of SAS® software package. In Experiment 1, the weight difference between eggs produced by young and mature breeders was 10.92 g, and the component that mostly influenced this difference was the yolk (7.51 g heavier in mature breeders, compared with 4.23 g difference in albumen and 0.8 g in eggshell weights). Hatchling weight difference was 9.4 g higher in eggs from mature breeders. In Experiment 2, egg weight difference was only 0.74 g, but yolk weight was 4.59 g higher in the eggs of mature breeders. The results obtained in the present study indicate that hatchling weight is influenced by egg weight, and not by breeder age.

Effect of Fenbendazole on Turkey Semen Quality

Fenbendazole (FBZ) is an anthelmintic recently approved to treat and control nematode infections in growing turkeys. When administered to growing turkeys there are no detrimental side effects. However, when we used FBZ to treat nematodes in mature breeder toms, we observed a decrease in semen quality and a subsequent precipitous decline in fertility to less than 20% within 6 wk of administration. An experiment was designed to determine the impact of FBZ administration on aspects of spermatogenesis and semen quality. We discovered that although sperm viability and concentration was not significantly affected by FBZ, this drug significantly reduced sperm mobility. However, normal mobility resumed within 6 wk after FBZ administration. Fenbendazole binds to tubulin and interferes with microtubule assembly. Based on testes histology and the immunocytochemical localization of tubulin in spermatids and mature sperm, FBZ had no affect on any aspect of spermatogenesis. We suggest that FBZ may be affecting sperm mobility by some molecular alteration of the sperm tail axoneme or midpiece, both of which are tubulin-containing structures. If a breeding flock of toms become infected with nematode parasites, a flock manager has the following options: do not treat the toms, find an alternative to FBZ, treat the toms with FBZ and increase the sperm number and frequency of artificial inseminations, or treat the toms with FBZ and secure semen from an uninfected tom flock.

Involvement of corticotropin-releasing factor and adrenocorticotropic hormone in the ovarian maturation, seawater acclimation, and induced spawning of Liza ramada

In the present study, we investigated the distribution and activities of corticotropin-releasing factor (CRF) and adrenocorticotropic hormone (ACTH) immunoreactive (ir) cells in the brain and pituitary of Liza ramada during ovarian maturation, seawater acclimation, and induction of spawning. Using immunohistochemistry, we detected that CRF-ir cell bodies exist in different brain regions: medulla oblongata (MO), midbrain tegmentum, habenula, nucleus preopticus (NPO), and in a ventral hypothalamic region corresponding to the nucleus lateralis tuberis (NLTP). In the pituitary gland, we detected some ACTH-producing cells in the rostral pars distalis (RPD) containing CRF immunoreactivity. The synthetic and secretory activity of CRF-ir cells in the NPO and MO as well as ACTH-ir cells in the pituitary were enhanced during ovarian maturation. During seawater acclimation, CRF-ir cells in the NPO and MO and ACTH-ir cells in the pituitary showed dramatic increases in their synthetic activity. These cells showed dramatic increase in their secretory activity during spawning induced by human chorionic gonadotropin (HCG) injection in L. ramada. Finally, hormonally induced ovulation was accompanied with elevation of plasma cortisol and depletion of CRF and ACTH immunoreactivity within the brain and the pituitary gland, respectively. Taken together, our findings suggest that mature breeders of L. ramada may respond to stress resulting from ovarian maturation, and seawater acclimation as well as induced spawning. Mechanisms include enhancement of the synthetic and/or secretory activity of CRF-ir cells in the NPO and MO as well as ACTH-ir cells in the pituitary gland along with a rise in plasma cortisol during ovulation, supporting the possible role of these hormones during stress and reproduction in L. ramada.

Effect of feeding green onions (Allium ascalonicum) to White Chinese geese (Threskiornis spinicollis).

Sudden increase in mortality was observed in 2 different flocks of mature breeder geese fed green onions. At necropsy, birds had pale epicardium with random petechiation, sanguinous fluid accumulation in the pericardial sac, and mild swelling of the liver and spleen. Histologically, there was accumulation of hemosiderin in hepatocytes, Kupffer cells of the liver, macrophages, and renal tubules. There was also moderate to severe hepatic necrosis, vacuolation of hepatocytes, splenitis, and renal tubular nephrosis. To assess the effects of green onion ingestion, 2 feeding trials were carried out in 3 mature White Chinese geese. In the first trial, onions were thoroughly mixed with pellet maintenance ration. In the second trial, onions were offered in a separate trough from the pelleted diet. During the 21 days of experiments, the red blood cell count and hematocrit decreased, whereas the polychromasia and reticulocyte estimate increased. The blood changes were more marked in birds from the second feeding trial. Gross and histologic changes were similar in both trials. Mild swelling and severe darkening of the liver were the only significant findings at necropsy. Histologically, the liver looked similar to that seen from the field outbreak. The liver contained moderate amounts of hemosiderin in the hepatocytes and Kupffer cells, and had centrolobular necrosis and vacuolation of hepatocytes. This experimental study demonstrated that anemia and liver pathology could be caused by ingestion of onions. Furthermore, Heinz bodies are not a consistent finding in the blood of geese fed onions.

The Circulating Levels of Lipoproteins in Embryos and Newly Hatched Ducklings Change with Parental Age1

The purpose of this study was to investigate the effects of duck breeder age on circulating very low density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels in embryonic (day 25 of incubation) and newly hatched ducklings (hatch and 1, 2, 3, and 5 days after hatch). In this study, embryos and ducklings from one breeder flock were monitored at breeder ages 24 weeks (young breeders), 31 weeks (mature breeders and near peak egg production), and 47 weeks (after peak egg production). Embryos and newly hatched ducklings from young breeders (24 weeks of age) displayed lower levels of VLDL and LDL. The composition of VLDL was affected by breeder age such that embryos and ducklings from young breeders had less cholesterol ester/protein and triglyceride/protein ratios. Even though the overall levels were suppressed in embryos and newly hatched ducklings from 24-week-old breeders, the overall percentage of triglyceride within VLDL and LDL particles was higher. These data would suggest that breeder age affects concentration and composition of both VLDL and LDL in embryos and newly hatched ducklings.

Stock improvement of silver barb ( Barbodes gonionotus Bleeker) through several generations of genetic selection

This paper reports stock improvement of silver barb ( Barbodes gonionotus Bleeker) using selective breeding techniques and presents the results of three generations of growth performance between selected and nonselected control groups. The breeding program was initiated using two wild caught populations from Thailand and Indonesia and an existing local stock from Bangladesh. To produce the parental base population in 1996, the three unrelated founder stocks were mated through a complete 3×3 diallele crossing experiment to produce nine heterogeneous, outbred genetic groups. In 1997, the first generation (F 1) trials were made. For each of the six reciprocal crosses, five to eight pairs were mated separately and the best three progeny groups were selected on the basis of egg fertilization rate, lack of deformities, healthy movement, and survival to make 18 full sib progeny lines. These were then communally stocked by mixing equal numbers of larvae from each family and grown until maturity in ponds. During the spawning season of 1998, the heaviest 20% of mature females and males were mass selected from the F 1 communal crossbred group and mated to produce the F 2 generation. In 1999, mass selection was again performed, selecting 15% of the best mature breeders from the F 2 generation to produce the third generation (F 3) for trials. In each generation, evaluation of growth performance was carried out through comparative trials between selected and nonselected control (existing stock of Bangladesh, B×B) groups. A 7.5% genetic gain in growth performance was attained by the F 1 crossbred group over the nonselected control group. The F 2 and F 3 selected groups attained 2.3% and 12.1% cumulative weight gain, respectively, over two generations. The average gain per generation across two generations of selection for growth performance in weight was estimated as 7.2%. The weight gain values of the third generation of the selected group showed 21.9% superiority over the nonselected control. Present findings suggest that the method for improvement of silver barb through several generations of genetic selection might be a useful technique for other carp species in Bangladesh and elsewhere in Asia.

Liver Lipid Accumulation in Duck Embryos and Hatchlings Change with Parental Age1

The purpose of this study was to investigate the effects of duck breeder age on liver lipid accumulation and yolk absorption and utilization in duck embryos (day 25 of incubation) and newly hatched ducklings. One breeder flock was monitored at 24 (young breeders), 31 (mature breeders and near peak egg production) and 47 (post peak egg production) weeks of age. Electron microscopy images of duck embryo liver slices revealed a significant change in hepatic lipid accumulation as a function of breeder age. More specifically, as breeder age increased both the relative number of liver lipid droplets as well as the size of the lipid droplets increased in duck embryos (day 25 of incubation). At hatch, however, newly hatched ducklings from 31-week-old breeders exhibited the lowest number as well as the smallest sized lipid droplets when compared to ducklings from 24 or 47-week-old breeders. The trend in yolk absorption at day 25 as a function of breeder age paralleled that in liver lipid accumulation. That is, day 25 maintained a higher percentage of unabsorbed yolk when compared to embryos from 31- or 47-week-old breeders. In contrast to breeder age, time of incubation (day 25 vs. day 28 or hatch) had little effect on yolk fatty acid profiles when compared to breeder age. Although there were no clear trends in yolk fatty acid usage among the various ages of breeders, newly hatched ducklings from 31-week-old breeders did have a significantly higher proportion of 18:2 n6 compared to those from breeders at 24 or 47 weeks of age. These data would suggest that breeder age subsequently affects the relative number and size of liver lipid droplets in embryos and newly hatched ducklings.

Characteristics of Fowl Cholera Outbreaks in Turkeys in Georgia in 1986

Information was gathered from 64 cases of fowl cholera (FC) in turkey flocks through diagnostic case records, flock records, and telephone and mail surveys. Forty-five cases came from flocks of commercial turkeys, of which 15 were presented twice, and four came from mature breeder flocks. The prevalence of FC was 18.0% of commercial flocks and 14.7% of breeder flocks at risk. The average age at first diagnosis of FC was 90 days in commercial turkey flocks and 32 weeks 5 days in breeder flocks. Acute mortality was the most common presenting complaint, with a 0.37% average mortality in commercial flocks on the day of first presentation, 0.80% in commercial flocks presented a second time, and 0.43% in breeder flocks. Pasteurella multocida was cultured from 69.8% of the 361 tissue samples submitted from these cases. Novobiocin, penicillin, and chlortetracycline (CTC) had the greatest in vitro activity against isolates. Serotype 3-cross-4 was found in all 18 commercial flocks from which isolates were typed. All breeder flocks and 88.6% of commercial flocks were vaccinated before disease onset. Flocks were treated for an average of 14.3 days, most commonly with high levels of sulfadimethoxine and/or CTC. Body weights of affected birds were comparable to those of birds in unaffected flocks, but mortality and feed efficiency were worse.

Testosterone Concentrations in Blood and Seminal Plasma of Turkeys Classified as High or Low Semen Producers

The interrelationships between concentrations of testosterone in blood plasma, seminal plasma (SP) of ductus (d.) deferens semen, and SP of the ejaculate of mature breeder turkeys were compared. The concentration of testosterone in blood plasma was greater than, and positively correlated with (r = .75, P<.01), the concentration of testosterone in the ejaculate SP and d. deferens SP. Differences between concentrations of testosterone in blood plasma, ejaculate SP, and d. deferens SP were not significantly different for turkeys classified as high (ejaculate volume > .38 mL) or low (ejaculate volume < .26 mL) volume semen producers. Concentrations of testosterone in blood plasma and SP were not correlated with ejaculate spermatozoal concentration, total number of spermatozoa, d. deferens semen volume, or testicular weights.

The influence of urine from asymptotic laboratory populations on sexual maturation in prairie deermice

SummaryMale and female prairie deermice housed singly from weaning (21 days) until 40 days of age had urine from one of the following sources applied daily to their nostrils: sexually mature laboratory population males or females, and sexually mature breeder males or females from our laboratory colony. Other males and females were treated with water. Records were obtained of the weights of the tests, seminal vesicles and bacula of males and the ovaries and uteri of females at 40 days of age.The major results of this study were as follow: Female urine from sexually mature and inhibited population or isolated mice stimulated the development of the male reproductive organs significantly more than water or male urine. Male urine applied to young males did not differentially affect the weights of their reproductive organs compared with water and thus showed no inhibition effects.The reproductive organs of females treated with male urine did not differ significantly in weight from those of females treated with female urine. Females treated with water developed significantly larger uteri than those treated with urine from sexually mature population females (P≤0.02), inhibited population females (P&lt;0.001) and inhibited population males (P&lt;0.007).

Reproduction of Penaeus kerathurus using eyestalk ablation

In a preliminary experiment on the induction of sexual maturity in Penaeus kerathurus by unilateral eyestalk ablation, spawning was obtained in 94% of the females treated. The time necessary to reach the spawning stage appeared to be closely related to the stage of natural physiological development of the gonads and the length of the photoperiod, the period between ablation and spawning decreasing from 69 days for females treated in November to about 10 days for females treated at the beginning of their natural reproductive period in May/June. Spawning after treatment was repeated up to eight times, sometimes at intervals of less than 10 days, without showing a decrease in the amount of fertile spawn. The mean number of fertile eggs per spawn was 78.400, which is not significantly different from the corresponding mean obtained previously after thermal stimulation of almost mature breeders; the hatching percentage, 67%, was also similar. Often only the anterior and median lobes of the ovaries are included in the spawning process. The discharged spawn is nearly always completely free of matrix material. It is anticipated that induction by eyestalk ablation could allow a considerable extension of the growing season and of the area suitable for culture.

The Relation of In Vivo and In Vitro Tocopherol Supplementation to Stability of Fowl Fat

The quality of rendered leaf fat from mature breeder fowl which contained varying amounts of tocopherol due to in vivo dietary supplementation or due to direct in vitro addition was investigated. Treatments were dietary supplementation with d-alpha-tocopheryl acetate at levels of 0, 0.025, 0.050, 0.075 and 0.100% (0 to 1360 I.U./kg. feed) for 3 weeks pre-slaughter and in vitro d-alpha-tocopherol addition of 0, 10.74, 21.48, 32.22 and 42.96 μg./ml. of rendered fat (0 to 6.4 I.U./100 ml. fat) of fowl fed 3 weeks on a diet containing no tocopherol supplementation. Parameters used to estimate fat quality included AOM stability time, free fatty acid content, initial peroxide value, and moisture and volatile matter content. Tocopherol content of the rendered fat was also determined.Fat tocopherol content was found to be significantly related to AOM stability time (r = 0.93, P < 0.01). The relationships of amount of in vivo or in vitro supplementation to the amount of tocopherol recovered in the fat and to AOM stability time were linear, positive and highly significant. The in vivo and in vitro methods of supplementation had significantly (P < 0.01) different effects on fat tocopherol content. Significantly less tocopherol was necessary to be present in the fat for in vivo vs. in vitro supplementation to obtain similar AOM stability times. However, in vivo supplementation required over 400 times the amount of tocopherol compared to in vitro supplementation to reach fat tocopherol levels where AOM stability times were similar. From these results in vitro addition of tocopherol appears to be the more economical and efficient procedure to improve quality and stability of rendered fowl fat.

A Study of the Feed Consumption of Breeder Males

ABSTRACT Numerous studies have been made previously by various other workers to determine the feed consumption of laying hens, chicks and turkeys. The amount of feed required to obtain certain selected average live weights of young males also has been determined (Titus, 1937) but to the knowledge of the authors, no data have been reported specifically giving the feed consumption of mature breeder males. It has been assumed in most nutritional and economic studies that mature breeder males eat slightly more than the females when fed the same hen ration. This experiment was designed to secure an estimate of the actual feed consumption of such males. Sixteen 1-year-old New Hampshire males (8.7 pound average weight) that were used for breeding purposes at this institution were divided into two groups of eight birds per group. The birds were housed in individual 2′×2′ pens with two birds sharing a waterer and feed hopper. . . .