Responses of the reproductive vascular system during the egg‐formation cycle of unanaesthetised laying hens

1. Vascular adjustments to the process of egg formation were examined in the unanaesthetised laying hen, by the radioactive microspheres method.

2. Three‐ to four‐fold increases in blood flow were found in segments surrounding the egg during its passage along the oviduct, possibly due to an enhanced metabolic activity in the muscle layer of the oviduct.

3. Shell‐gland blood flow was minimal in the absence of an egg and increased gradually to a maximum (5‐fold) about 5 h after entrance of the egg into the shell gland. This parallels the rate of calcification of the egg shell.

4. Changes in blood flow in the ovarian follicles and other parts of the oviduct were small while the egg was in the shell gland. This might be typical for the reproductive system of the fowl, which undergoes little structural alteration during egg formation.     

Some observations on the caecal micro‐flora of the chick during the first two weeks of life

1. Changes in the caecal flora of chicks aged from approximately 3 h to 14 d were studied.

2. Counts obtained by means of a conventional anaerobic plating method and a method for the stricter anaerobes remained comparable throughout but occasionally it was found that strains of anaerobic bacteria isolated from the predominant flora of 4‐ to 14‐d‐old birds could not be grown when tested by the conventional method.

3. During the 14‐d period approximately 100% of the organisms isolated on anaerobic plates utilised uric acid up to the third day but the incidence subsequently declined and in one case represented only 4% of the total flora.

4. The predominant uric acid‐utilising bacteria were Streptococcus faecalis and Escherichia coli up to 3 d of age and various types of anaerobic bacteria thereafter.

5. None of the isolates showed an absolute requirement for uric acid.     

Cross‐contamination during the scalding and plucking of broilers

1. Experiments were carried out in two poultry slaughtering plants to estimate cross‐contamination occurring during the scalding and plucking of broilers.

2. To simulate the external (dust and feather) and internal (intestinal) contamination of broilers the carcasses were artificially contaminated with a strain of Escherichia coli K12.

3. Cross‐contamination occurred at both stages in the processing when the carcasses had been contaminated externally; when the broilers had been contaminated internally slight cross‐contamination occurred only during plucking.

4. Broilers which were contaminated externally before scalding resulted in more numerous carcasses that were contaminated after the whole slaughtering procedure than those contaminated internally.

5. In one processing plant there were fewer contaminated carcasses after cooling than after plucking, while in the other plant no differences were found in the number of positive carcasses after these two stages in processing.     

Transmission of Theileriosis in the Traditional Farming Sector in the Southern Province of Zambia during 1995–1996

The incidence of first contact with the protozoan Theileria parva was determined in three traditional cattle herds in the Southern Province of Zambia in 1995 and 1996. The majority of first contacts occurred during the dry season in June, July and August, at a time of nymphal activity and in the absence of Rhipicephalus appendiculatus adults, indicating that larva to nymph transmission plays a more prominent role than nymph to adult transmission under the prevailing conditions.     

Expression and distribution of intermediate-filament proteins and laminin during the development of the bovine Müllerian duct

The expression pattern of several intermediate-filament proteins (vimentin, cytokeratin 8, 18 and 19) and the basal lamina component laminin was investigated in the Wolffian and the Müllerian ducts of bovine embryos and fetuses. The material studied comprised sexually undifferentiated stages [crown-rump length (CRL) 0.9 cm/1.0 cm/1.2 cm/1.9 cm/2.5 cm] and female stages (CRL 3.0 cm/4.2 cm/5.1 cm). Laminin could be demonstrated in the basal lamina of the developing Wolffian and Müllerian duct as well as in the stroma surrounding the Müllerian duct. The intermediate-filament protein vimentin was expressed in the mesothelium of the funnel field and in the epithelium of the Müllerian duct in all studied specimens, whereas the epithelial cells of the Wolffian duct only showed vimentin expression from a CRL of 2.2 cm onwards. In the cranial part of the Müllerian ducts only a few cells stained with pan-cytokeratin antibodies, whereas mesothelium and epithelium of the Wolffian duct showed as distinct immunostaining in all investigated stages. Both genital ducts showed no immunostaining with the antibody against cytokeratin 19 at any time of development. We conclude from our immunohistochemical results that the epithelial cells of the Wollfian duct do not contribute cells to the developing Müllerian duct.     

Transmission of Theileria parva in the Traditional Farming Sector in the Southern Province of Zambia during 1997–1998

The incidence of first contact with the protozoan Theileria parva was determined in two traditional cattle herds in the Southern Province of Zambia during a period of average rainfall in 1997 and 1998, following a drought in the previous two years. Compared to that period, there was a marked increase in the number of rainy season first contacts attributable to transmission by Rhipicephalus appendiculatus adults. However, there were still more dry season contacts that resulted from nymphal transmission. These results highlight the important role that climate plays in the transmission of theileriosis in the Southern Province of Zambia.     

Plasma inorganic phosphorus concentration during egg‐shell formation: Effect of the physical form of the dietary calcium

1. Four experiments were carried out with Warren laying hens to elucidate the changes in plasma inorganic phosphorus (P_i) concentration during egg formation.

2. In hens receiving a normal diet containing a calcium supplement in a powdery form P_i increased from 25 to 42 mg/1 during an entire shell formation cycle (from 10 to 22 h after oviposition of the previous egg), while in cockerels P_i decreased slightly during the night.

3. This increase in P_i in hens, was not related to cessation of feeding at the onset of darkness but was specifically connected with the beginning of shell secretion.

4. When hens received calcium as crushed sea‐shells separately from the diet, the nocturnal peak in Pi virtually disappeared and only a temporary increase of 4 mg/1 between 10 and 14 h after oviposition remained.

5. These results indicate that the beginning of shell secretion is always accompanied by an increase in Pi and that a separate presentation of dietary calcium reduces the bone mobilisation at night.     

Comparative efficacy of three antibiotic products for the treatment and prevention of sub‐clinical mastitis during the dry period

Summary

The comparative efficacy of a product containing 500 mg benzathine cloxacillin (Orbenin D.C.), another product containing 100 mg nafcillin, 300 mg procaine benzylpenicillin and 100 mg dihydrostreptomycin (Nafpenzal D.C.) and a third product containing 250 mg cephalonium (Cepravin D. C.), in the elimination and prevention of mastitis due to gram‐positive microorganisms during the dry period was investigated in 1253 cows located in 14 herds in Israël.

Although more uniform results were observed after treatment with Nafpenzal D.C., differences were not found among the products with respect to the overall efficacy but differences among herds were rather large. The mean cure rate for Staphylococcus aureus quarter infections was 81.4 per cent. New S. aureus infections which occurred between drying off and post calving sampling time were found in 7.0 per cent of the quarters.

Dry period therapy reduced infection level with S. aureus from 13.5 per cent of quarters to 8.0 per cent. A similar proportional decrease was found in infection level due to non‐agalactiae Streptococcus quarter infections.     

Seasonal or pathological findings? Morphofunctional characteristics of the equine endometrium during the autumn and spring transition

The deep anoestrous phase in winter is part of the anovulatory season in mares and is bordered by the autumn and spring transitional periods (ATP/STP). To define an annual time span for effective prognostic biopsy sampling, the aim of this study was to provide a morphofunctional characterization of the endometrium during ATP and STP. To outline both transitional periods, endometrial specimens were taken in September, October and November (n = 76) as well as February, March and April (n = 184) with the requirement of a detailed clinical documentation. Tissue samples were examined histologically with special emphasis on the functional endometrial morphology. Additionally, an immunohistochemical evaluation was performed on selected specimens regarding the expression of oestrogen receptor α, progesterone receptor and Ki67‐antigen. An absent to low endometrial activity was ascertained in more than 60% of all specimens from late October onwards, whereas a comparably lacking or low activity in STP was observed until early April. Approximately 30% (ATP) to 22% (STP) of all samples exhibited a predominantly “irregular” endometrial differentiation. During the transitional periods, the clinically evaluated ovarian status (transrectal palpation, transrectal ultrasonography and/or serum progesterone and oestrogen analyses) and the endometrial functional morphology were in accordance with approximately 70% of all cases. The expression of steroid hormone receptors and Ki67‐antigen was generally low. Given that endometrial maldifferentiations were frequently found during ATP and STP, its occurence might display a characteristic and physiological feature of the transitional periods. Regarding the functional endometrial morphology, a diagnostic biopsy sampling should therefore be performed between late April and before September.     

Studies on the avian shell gland during egg formation: The effect of acetazol‐amide on the transfer of ions to the albumen 1

1. Twenty‐five laying hens were fed on a diet containing 100 mg acetazolamide/kg in order to determine the effects of a decrease in the activity of carbonic anhydrase on the transfer of minerals to the egg albumen.

2. Treatment with acetazolamide decreased the rate of shell formation by 44%; reduced the concentrations of water and Na+ in the albumen at the beginning of the plumping stage but increased the accumulation of water during plumping; increased the concentration of Cl‐ in the albumen after the 6‐h stage without any appreciable change in K+ and Ca²⁺ concentrations.

3. The computed relationships between the concentrations of different ions also showed that the transfer of water and Na+ were linked during egg formation, that a water‐independent, acetazolamide‐sensitive reabsorption of Na+ occurred after the 10‐h stage and that Na+ and Cl‐moved simultaneously up to 14 h but with the ratio of Cl‐ to Na+ three times higher in the treated group.

4. It is concluded that acetazolamide impairs the transfer of Na+ and Cl‐ between the albumen and the extracellular fluid and that secretion of Ca²⁺ into the uterine lumen seems to depend on Na+ and Cl‐ reabsorption.     

Does orchiectomy enhance the immune-stimulatory effects of melatonin during experimental Chagas’ disease?

Melatonin has been reported to play a fundamental role in T-cell immunoregulation. Control of Trypanosoma cruzi parasitism during the acute phase of infection is considered to be critically dependent on direct macrophage activation by cytokines. The aim of this work was to evaluate the influence of exogenous melatonin treatment and the influences exerted by sexual hormones during the acute phase of the experimental Chagas' disease in rats. With melatonin treatment, orchiectomized animals (CMOR and IMOR) displayed the highest concentrations of IFN-γ and TNF-α. On the 7th day post-infection, untreated and treated orchiectomized animals (IOR and IMOR) showed an enhanced number of peritoneal macrophages. Nitric oxide levels were also increased in untreated and treated orchiectomized (IOR and IMOR) when compared to the other groups, with or without LPS. Our data suggest that melatonin therapy associated with orchiectomy induced a stimulating effect on the immune response to the parasite.     

Ultrastructural changes of osteoclasts on hen medullary bone during the egg‐laying cycle

1. The ultrastructure of osteoclasts on hen medullary bone during the egg‐laying cycle was observed by electron microscopy.

2. At 0 to 6 h after oviposition, osteoclasts lacking ruffled borders were attached to the bone via the clear zone and appeared to have ceased bone resorption. Small vacuoles were scattered throughout this cytoplasm.

3. At 9 to 21 h after oviposition, most of the osteoclasts had ruffled borders and appeared to be resorbing bone. The ruffled borders at 15 h were well developed, whereas at 9, 18 and 21 h they were poorly developed or showed similarities in structure to the clear zone. The small vacuoles were concentrated under the ruffled borders at 9 h and then decreased.

4. These results demonstrate cyclic changes in osteoclasts during the egg‐laying cycle, indicate that ruffled borders form at the beginning of bone resorption and suggest that they are derived from the clear zone and the small vacuoles. The results also indicate that the ruffled borders fuse into the clear zone and disappear at the completion of bone resorption.     

Effect of restricted feeding during the rearing period and a “forced moult” at 40 weeks of production on the productivity of Pekin breeder ducks

1. Six males and 24 female Cherry Valley Pekin ducklings were randomly allocated to each of 12 pens to test the effects of quantitative food restriction during the rearing period on the subsequent reproductive performance. At the end of the laying period (60 weeks) a “forced moult” was introduced and its effect on a further 40 weeks production investigated.

2. The 3 rearing treatments were 50% of ad libitum intake from 3 to 20 weeks; 75% of ad libitum intake from 3 to 20 weeks and ad libitum intake throughout. During the laying period (20–60 weeks) and post forced‐moult period (60–100 weeks) duck breeder pellets were fed ad libitum to all groups.

3. Highly significant (P ≤ 0.01) differences in favour of the restricted groups over the ad libitum‐fed groups were observed in most of the responses studied. The following were the main advantages of food restriction: lower lifetime food intake, lower carcase fat content at 20 weeks, delay in sexual maturity, higher egg production, higher peak and terminal production, higher fertility, higher hatchability of eggs set and lower mortality. Egg mass and hatchability of fertile eggs was not influenced by food restriction in this experiment. The use of a “forced moult” showed that it could be of economical importance.

4. Differences between treatments in respect of absolute and relative visceral masses were also investigated. The absolute masses of the intestine, heart, gizzard and liver all decreased as the degree of food restriction increased. The relative visceral masses showed the opposite trend with the exception of the heart which showed no significant differences between treatments.     

Temporal changes in the expression of avian β-defensins in the chicken vagina during sexual maturation and Salmonella infection

Avian β-defensins (AvβDs) constitute a family of antimicrobial peptides that are critical to innate immunity in chickens, providing protection against microbial pathogens including Salmonella Enteritidis (SE). As apart from the digestive tract another main route of SE colonization in birds is via infection of the oviduct and specifically of the vagina, the aim of this study was to investigate the expression of the complete family of AvβDs, in the chicken vagina in vivo, to determine whether sexual maturation affects their mRNA abundance and to investigate whether SE infection alters the vaginal AvβDs expression. Expression analysis revealed that 11 members of the AvβD family were expressed in the chicken vagina. Quantitative real-time PCR analysis revealed that the mRNA abundance of five AvβDs was up regulated and of one AvβD was down regulated with respect to sexual maturation. In addition SE infection resulted in a significant induction of AvβD5, 7, 10, 11, 12 and 14 in the vagina of sexually mature birds, and in a significant induction of AvβD5 and 11 in the vagina of aged birds. These findings provide strong evidence to suggest that an AvβD-mediated immune response mechanism exists in the chicken vagina providing protection against bacterial pathogens including Salmonella species.     

Day‐length during rearing and the subsequent egg production of meat‐strain pullets

1. The effects of lighting pattern on production to 399 d in caged, female, meat‐strain chickens was investigated. Energy intake was controlled from 56 to 399 d.

2. Four different rearing treatments with a subsequent constant 16‐h photoperiod during laying were used.

3. A 15‐h rearing photoperiod resulted in delayed sexual maturity, increased mature body weight and decreases in both total egg numbers and the proportion of smaller eggs, compared with a 6‐h photoperiod.

4. Continuous light to 56 d, although associated with a high incidence of subsequent blindness, resulted in satisfactory egg production.

5. Abrupt reduction in the photoperiod from 15 to 6 h for the 112 to 167 d period resulted in unsatisfactory subsequent performance, especially when the day‐length was only slowly increased to 16 h during laying.

6. In the two laying treatments, in which the photoperiod was increased gradually from 6 to 16 h during the 168 to 238‐d period, a decrease in the number of smaller eggs occurred, compared with the treatments in which a single abrupt increase in photoperiod was used.     

Immune response during the onset of coliform mastitis in dairy cows vaccinated with STARTVAC®

The immune response during the onset of coliform mastitis in vaccinated cows was investigated by measuring lactoferrin (LF), interleukin-8 ( IL-8), and interleukin-1β (IL-1β) concentrations and somatic cell counts in 28 milk samples at the onset of acute coliform mastitis (ACM) and 73 milk samples at the onset of peracute coliform mastitis (PCM). Vaccinated ACM, unvaccinated ACM, and vaccinated PCM showed significantly higher values for LF and IL-1β levels than unvaccinated PCM (p < .01). The IL-8 concentration was lower in vaccinated PCM than in unvaccinated PCM (p < .05). There was no significant difference in somatic cell counts for each parameter. There were no significant differences in the parameters between vaccinated and unvaccinated ACM cows, or vaccinated ACM and PCM cows. From the above results, it is suggested that mastitis vaccination improved the early immune response, particularly at the onset of PCM, and played a large role in host defense against the initial infection.     

Can an external device prevent dorsal displacement of the soft palate during strenuous exercise?

REASONS FOR PERFORMING STUDY: Dorsal displacement of the soft palate (DDSP) is a common condition in racehorses for which various surgical treatments are often performed. In light of recent findings that suggested the position of the larynx may influence the occurrence of DDSP, we investigated whether a noninvasive mean of affecting the position of the larynx could be effective in the management of DDSP. HYPOTHESIS: An external device (laryngohyoid support; LHS) positioning the larynx in a more rostral and dorsal location and preventing caudal displacement of the basihyoid bone would be effective in preventing DDSP during strenuous exercise. METHODS: Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control (n = 10); control with external device (n = 10); after bilateral resection of thyrohyoid (TH) muscles (n = 7); and after bilateral resection of TH muscles with external device (n = 7). Two trials were performed randomly for each of the 4 conditions. In Trial 1, videoendoscopic images of the upper airway, pharyngeal and tracheal static pressures, and arterial blood gases were collected. In Trial 2, airflow measurement combined with mask and tracheal static pressure was obtained, and upper airway impedance calculated. The trials allowed calculation of airway impedance and respiratory frequency, and assessment of ventilation using arterial PO2 and PCO2. RESULTS: Under control conditions, none of the 10 horses developed DDSP. There was no statistically significant effect from the LHS on airway impedance or respiratory frequency, nor on arterial PO2 and PCO2. Seven of the 10 horses developed DDSP during exercise after resection of the TH muscles. None of these 7 horses continued to experience DDSP during exercise with the external device. In the latter group and condition, the LHS significantly improved inspiratory and expiratory flow and impedance. CONCLUSIONS: The LHS helped prevent experimentally induced DDSP at exercise, probably by statically positioning the larynx in a more rostral and dorsal position. POTENTIAL RELEVANCE: Field studies are required to investigate whether the LHS can successfully prevent DDSP in horses with naturally occurring disease.