Inheritance of reproductive traits of female common ducks (Anas platyrhynchos) in pure breeding and in inter-generic crossbreeding with muscovy ducks (Cairina moschata)

1. Genetic parameters of reproductive traits were estimated in a population of common duck, in purebreeding and crossbreeding (with Muscovies) insemination systems. A total of 989 females were studied over three generations as well as 4025 purebred offspring and 4,125 male mule offspring. 2. Traits studied were age at first egg, total number of eggs laid until the age of 48 weeks, fertility and hatchability rates in pure and crossbreds, weight at 6 and 30 weeks of age, average egg weight and body weight of the male mule ducks at 6 weeks of age. 3. Heritability estimates were found to be medium range for reproductive traits (0.15 to 0.47). Heritability value for fertility or hatchability in crossbreds was twice as high as in purebreds (0.32 vs 0.15 for fertility; 0.36 vs 0.16 for hatchability). 4. Fertility in purebreeding and in crossbreeding were two different traits (r(g) = 0.49) while hatchability displayed a high genetic correlation between breeding systems (r(g) = 0.88). 5. Genetic correlations with number of hatched mule ducks were medium or high and favourable. Genetic correlations between reproductive traits and weights were low (< 0.36), the most related trait being the body weight of the male mule duck at 6 weeks of age.     

Crossbreeding effects on reproductive traits in two strains of duck (Anas platyrhynchos): Brown Tsaiya and Pekin

1. The reproductive performances of 211 domestic duck females (Anas platyrhynchos) from the pure breeds Brown Tsaiya (Ts) and Pekin (Pk) and their two reciprocal crossbreds were analysed.

2. Differences in the 4 genotypes, additive direct and maternal crossbreeding effects and heterosis were estimated on the following traits: age at first egg, egg production to the ages of 30, 35, 40 and 52 weeks of age, egg weight at 30 weeks of age, and (egg) fertility by artificial insemination with Muscovy drakes’ pooled semen.

3. Egg production up to 52 weeks of age was higher in Ts than in Pk (respectively 214 ± 7 and 150 ± 8 eggs), but not statistically different from that of the reciprocal crossbreds. The ratio of settable eggs to total eggs was nearly 90%, without any difference between genotypes.

4. Average egg weight at the age of 30 weeks was 75 ± 0.9 g for Pk, which was higher than the corresponding values for Ts (62 ± 0.8 g), but not significantly different from the crossbreds.

5. An effect of genotype was found on egg fertility: the Pk strain exhibited the lowest value, 71.3 ±3.1% compared with 75.9 ±2.1% for Ts, 80.6 ± 2.6% for Ts × Pk and 74.6 ± 1.9% for Pk × Ts.

6. Crossbreeding genetic variables showed favourable direct genetic effects for egg production and (egg) fertility in Ts, while Pk had favourable direct genetic effects on egg weight. The Pk genotype had a favourable maternal effect on fertility. Direct heterosis was 34% and 10% for egg production up to 30 and 52 weeks of age respectively, 8.8% for egg weight and 5.4% for (egg) fertility.

7. Crossing Ts with Pk seems profitable for the production of mule ducklings.     

The SNP genotypes of growth hormone gene associated with reproductive traits in Tsaiya ducks

Our previous cDNA microarray study showed that the growth hormone (GH) gene may involve in the duck egg formation process. The purpose of this study was to investigate the relationship between GH genotypes of single nucleotide polymorphisms (SNPs) and reproductive traits of Tsaiya ducks. Primer pairs for the coding region in the GH were designed based on the duck genomic sequence. Polymorphisms were detected by polymerase chain reaction (PCR)-single strand polymorphism (SSCP) and were verified by DNA sequencing. Nineteen SNPs were identified in the duck GH gene, of which three coding SNPs (C3169T, C3700T and C5058G) were genotyped to investigate the associations with reproductive traits. The results showed that each SNP was associated with at least one duck fertility-related trait (p < 0.05). Haplotypes constructed on these three SNPs were associated with fertility rate (FR) and maximum duration of fertility (MDF) (p < 0.05). In particular, diplotype H1H1 was dominant for FR and MDF. This suggested that GH gene polymorphisms are associated with duck fertility-related traits. The SNPs in this gene may be used as potential markers for marker-assisted selection.     

Transmission of bovine virus diarrhoea virus (BVDV) by artificial insemination (AI) with semen from a persistently-infected bull

Twelve heifers that did not have antibodies to bovine virus diarrhoea virus (BVDV) were inseminated with semen from a bull that was persistently infected with the virus and contained 10(4.0)-10(6.5) TCID50 0.1 ml-1. All 12 became infected, as indicated by seroconversion within 2 weeks of insemination. Four control heifers were inseminated with virus-free semen. The virus was not transmitted to these animals in spite of close contact with the heifers inseminated with the infected semen. All the heifers became pregnant and gave birth to clinically normal calves at term. However, one calf was born persistently infected with BVDV. After the birth of this persistently-infected calf the control heifers and their calves seroconverted. The study demonstrates that BVDV may be transmitted in cattle by artificial insemination (AI). Therefore entry of persistently-infected animals into AI centres should be prevented.     

Genetic parameters from factorial cross breeding in two duck strains (Anas platyrhynchos) brown Tsaiya and Pekin,for growth and fatty liver traits

1. A total of 655 mule ducklings were produced in three hatches by artificial insemination of common duck females Brown Tsaiya and Pekin “Alienor” and of their 2 reciprocal crossbreds with Muscovy semen.

2. They were fed ad libitum until 6 weeks, then restricted to one meal per day until day 75 and afterwards preforce fed until day 84 and subsequently force fed by 2 crammers, twice a day, from the age of 85 d and for a maximum of 13 d.

3. Body weight at hatching, 28 d, 56 d, 75 d, 84 d and at slaughter, the number of force‐fed meals, the “paletot” weight, the fatty liver weight, the fat release rate after sterilisation of a 60 g portion of liver and the serous melting rate were measured individually.

4. Significant dam genotype and hatch effects were present for all traits. The crammer effect on force feeding traits was also significant. For mule ducks from Brown Tsaiya, Tsaiya X Pekin, Pekin X Tsaiya and Pekin dams respectively, mean body weight was 2356, 3219, 3137 and 3801 g at 12 weeks, “paletot” weight was 1585, 2111, 2110 and 2470 g, fatty liver weight was 441, 585, 563 and 641 g, fat release rate was 35·1, 40·5, 38·2 and 46·0%.

5. The estimated differences between Pekin and Tsaiya genetic effects in their mule progeny were significant and in favour of the Pekin, except for the number of force fed meals and for the serous melting rate. Grandmother genetic effects were not significant, but maternal heterosis h ^m was in general significant and favourable: it was 8·5% for birth weight, about 4% for growth traits and “paletot” weight, 6·2% for fatty liver weight and – 2·8% (not significant) for fat release rate. A crossbreeding system between a heavier Pekin breed and Tsaiya would be worth considering to improve the fatty liver production of mule ducks.     

Optimal timing for canine artificial insemination with frozen semen and parentage testing by microsatellite markers in superfecundency

Parentage testing was performed in sixteen litters by canine artificial inseminations with frozen semen from different sires on Days 5 and 7 after the LH surge. It became apparent that only 25% of dams had superfecundation, but 43.8% of dams were whelped after insemination only on Day 5 after the LH surge and 31.3% of dams after insemination only on Day 7. Of the total 87 puppies, 46% were born after insemination on Day 5 after the LH surge and 54% after insemination on Day 7. This result strongly suggested that canine artificial insemination with frozen semen could be sufficiently successful also on Days 5 and 7 after the LH surge.     

Lectin binding patterns in the olfactory bulb of mallard ducks (Anas platyrhynchos)

We histologically examined lectin binding patterns in the olfactory bulb of mallard ducks (Anas platyrhynchos) using 21 biotinylated lectins. Positive staining for the N‐acetylglucosamine‐specific lectins (Bandeiraea simplicifolia II, Datura stramonium, Lycopersicon esculentum, Solanum tuberosum, Triticum vulgare), galactose or N‐acetylgalactosamine‐specific lectins (Artocarpus intergrifolia, Phaseolus vulgaris erythroagglutinin, Phaseolus vulgaris leucoagglutinin, Ricus communis) and the mannose‐specific lectins (Lens culinaris and Pisum sativum) was observed in the olfactory nerve and glomerular layers. Canavalia ensiformis staining showed a similar pattern to that obtained with the lectins and there was also faint staining in the mitral cells. Olfactory nerve axons terminate in the glomeruli, where they make excitatory synapses with the dendrites of mitral cells. This finding indicates that glycoconjugates that bind Canavalia ensiformis play an important role in formation of glomeruli. No positive staining for the other lectins was seen in the olfactory bulb. Based on these results, we conclude that cell surface sugar moieties of the olfactory bulb in mallard ducks express N‐acetylglucosamine and mannose residues rather than N‐acetylgalactosamine residues. The carbohydrate composition of mallard duck olfactory bulb differed from that of other vertebrates found in previous studies.     

First report of parasitic esophagitis by Streptocara incognita in Muscovy ducks (Cairina moschata domesticus) in Italy

This work describes the first outbreak of streptocariasis by Streptocara incognita reported from Italy. The disease was observed in a backyard flock of 62 ducks (Cairina moschata domesticus) located in Treviso, northeastern Italy. Fifteen birds died in a period of 2 wk, showing debilitation and emaciation. Two ducks were submitted for postmortem examination and an esophagitis associated with nematodes was observed. The nematodes were identified as Streptocara incognita.     

Comparison of fluid types for resuscitation after acute blood loss in mallard ducks (Anas platyrhynchos)

Objective – The purpose of this study was to determine the LD₅₀ for acute blood loss in mallard ducks ( Anas platyrhynchos ), compare the mortality rate among 3 fluid resuscitation groups, and determine the time required for a regenerative RBC response.
Design – Prospective study.
Setting – Medical College of Wisconsin Research facility.
Animals – Eighteen mallard ducks were included for the LD₅₀ study and 28 for the fluid resuscitation study.
Interventions – Phlebotomy was performed during both the LD₅₀ and fluid resuscitation studies. Ducks in the fluid resuscitation study received a 5 mL/kg intravenous bolus of crystalloids, hetastarch (HES), or a hemoglobin-based oxygen-carrying solution (HBOCS).
Measurements and Main Results – The LD₅₀ for acute blood loss was 60% of total blood volume. This blood volume was removed in the fluid resuscitation study to create a model of acute blood loss. Following fluid administration, 6 birds in the crystalloid group (66%), 4 birds in the HES group (40%), and 2 birds in the HBOCS group (20%) died. No statistical difference in mortality rate was seen among the 3 fluid resuscitation groups. Relative polychromasia evaluated post-phlebotomy demonstrated regeneration starting at 24 hours and continuing through 48 hours.
Conclusions – The LD₅₀ for acute blood loss in mallard ducks was 60% of their total blood volume. Although no statistical difference in mortality rate was appreciated among the 3 fluid resuscitation groups, a trend of decreased mortality rate was observed in the HBOCS group. An early regenerative response was apparent following acute blood loss.     

Comparison of the effects of the degree of food restriction during rearing on ovarian function at the onset of lay in unselected ducks (anas platyrhynchos) and in a line selected for improved food efficiency

1. Ovarian structure and function at sexual maturity in two lines of ducks (selected or not selected for juvenile food efficiency), fed ad libitum or restricted to achieve 0.50, 0.65 or 0.80 of unrestricted body weight at 24 weeks, were compared in a randomised block factorial experiment.

2. Selected ducks were larger but not fatter or older at sexual maturity, had more yellow follicles, giving a greater potential for multiple ovulation, and a higher proportion of atretic yellow follicles, compared with unselected ducks.

3. There was a linear relationship between the number of normal yellow follicles and body weight at the onset of lay which was similar in the two lines.

4. Several birds on the most severe regimen failed to lay and it was concluded that ducks should be at least 0–6 of unrestricted body weight for the onset of lay.

5. Weight of the ovary with follicles less than 8 mm diameter was greater in selected compared with unselected ducks and in birds fed ad libitum compared with restricted ones.     

Determination of optimal time for mating by artificial insemination with chilled semen using luteinizing hormone surge as an indicator in beagles.

Artificial insemination (AI) was conducted using the second fraction of semen, which was collected from 15 male dogs, diluted to a total sperm count of 100x10(6) for each insemination with egg-yolk Tris (eyT) citrate acid buffer and incubated at 4 degrees C for 48 hours. Luteinizing hormone (LH) surge was detected to determine the optimal time for mating using canine LH assay kits. Artificial insemination using 100x10(6) sperm was performed on the fourth and sixth days or the fifth and seventh days after the LH surge. The conception rates were 33% (4/12) and 89% (8/9), respectively; the whelping rates also showed similar results. Serum LH and follicle stimulating hormone (FSH) concentrations were measured in nine dogs, and the mean LH concentration (+/- standard deviation) at LH surge was 15.77+/-7.66 ng/ml. The time of the LH surge detected by the canine LH assay kit was very similar to that measured by radioimmunoassay (RIA).     

Pharmacokinetics of doxycycline after a single intravenous,oral or intramuscular dose in Muscovy ducks (Cairina moschata)

1. The pharmacokinetics of doxycycline in ducks were investigated after a single intravenous (IV), intramuscular (IM) or oral (PO) dose at 20 mg/kg body weight.

2. The concentrations of doxycycline in plasma samples were assayed using a high performance liquid chromatography method, and pharmacokinetic parameters were calculated using a non-compartmental model.

3. After IV administration, doxycycline had a mean (±SD) distribution volume (V_z) of 1761.9 ± 328.5 ml/kg and was slowly eliminated with a terminal half-life (t_1/2λz) of 21.21±1.47 h and a total body clearance (Cl) of 57.51 ± 9.50 ml/h/kg. Following PO and IM administration, doxycycline was relatively slowly absorbed – the peak concentrations (C_max) were 17.57 ± 4.66 μg/ml at 2 h and 25.01 ± 4.18 μg/ml at 1.5 h, respectively. The absolute bioavailabilities (F) of doxycycline after PO and IM administration were 39.13% and 70.71%, respectively.

4. The plasma profile of doxycycline exhibited favourable pharmacokinetics characteristics in Muscovy ducks, such as wide distribution, relatively slow absorption and slow elimination, though oral bioavailability was low.

     

The development of a model for artificial insemination by backyard pig farmers in Thailand

The aim of this study was to develop and evaluate a model of artificial insemination (AI) technology transferable to backyard pig farmers for strengthening pig productivity in rural areas in Thailand. An AI center, criteria and process for farmer selection, an AI training program, AI practice in pigs, and a backyard farmer network were created as a model. Five hundred and thirty-one farrowing records from 307 sows were analyzed. Farrowing rates (FR), total number of piglets born (TB), and number of piglets born alive (BA) were studied. AI has led to better results in FR, TB, and BA than natural mating (P < 0.05). Demographic factors such as sex and age of farmers only had significant effects on FR (P < 0.05), while educational levels and farmers’ AI experience had significant effects on TB and BA (P < 0.05). Model factors such as type of training, semen delivery systems, and semen storage time did not have significant effects on FR, TB, and BA. In conclusion, using this model, we found that backyard farmers could be trained in AI techniques in order to achieve equally good results as experienced technicians. Male farmers within working age or older, with a high school education or higher are the recommended target groups for implementing this model. Strong cooperation with clear responsibilities of all stakeholders could create a good network of backyard pig farmers. Therefore, the implementation of AI techniques in pig production can be applied to the target group with an aim towards a sustainable, self-sufficient community.     

提高黄牛人工授精受胎率的经验体会

要开展好黄牛杂交改良工作 ,突出的问题是如何提高人工授精母牛的受胎率 ,笔者经过多年来的实践、体会 ,认为解决这个问题要采取如下技术措施。1　加强牛群饲养管理 ,提高营养水平 ,确保母牛繁殖生理正常　　饲养水平对母牛性器官的发育和性机能有显著影响。如饲料蛋白质不足 ,或缺钙、磷都能引起母牛卵巢机能不全或抑制排卵。缺乏维生素Ａ或Ｄ ,则胎儿发育不正常 ,甚至死亡或流产。冬春的枯草季节 ,如母牛仅靠放牧 ,则因营养不够而母牛膘情会显著下降。瘦弱的母牛 ,性腺萎缩 ,发情周期不规律 ,发情象征也不明显 ,甚至停止发情。瘦弱母牛进…