Influence of high dietary vitamin E supplementation on egg production and plasma characteristics in hens subjected to heat stress

1. The effects of different dietary concentrations of vitamin E (alpha-tocopherol acetate) were investigated in 2 experiments on laying hens exposed to chronic heat stress at 32C. 2. In the first experiment, egg production and plasma concentrations of calcium and egg yolk precursors were measured in 24 hens before, during and after a stress period of one week and fed on diets containing 10 or 500 mg vitamin E/kg. 3. In the second, larger experiment, egg production and food intake were measured in 300 hens housed in 2 temperature-controlled rooms and fed on diets containing 10, 125 or 500 mg vitamin E/kg. Birds in room 1 were stressed from 24 to 28 weeks of age and those in room 2 from 32 to 36 weeks. 4. In experiment 1, egg production and egg weight were significantly higher (72.6 vs 51.2%, P < 0.05 and 66.6 vs 63.1 g, P < 0.005 respectively) during and after the period of stress in the group given 500 mg vitamin E/kg. Plasma concentrations of calcium, vitellogenin (zinc) and VLDL (triglyceride) were also higher in this group. 5. In experiment 2, egg production was significantly higher (65.4 vs 56.2%, P < 0.05) during and after the period of heat stress in birds in room 1 fed on the diet containing 500 mg vitamin E/kg. Egg production was also higher (49.9% vs 44.7%) on this treatment during the stress period in room 2, though the difference was not significant (P < 0.10). Egg weight and food intake were unaffected by treatment in either room. 6. It is concluded that dietary supplementation with extra vitamin E can, at least in part, alleviate the adverse effects of chronic heat stress in laying hens, perhaps by maintaining the supply of egg precursors in plasma.     

Effect of soybean meal substitution by different concentrations of sunflower meal on egg quality traits of white and coloured dwarf dam lines

1. The effect of soybean meal substitution by different concentrations of sunflower meal on egg quality traits of white and coloured dwarf dam lines was investigated.

2. A total of 144 dwarf hens (38 weeks of age) from the same hatch were randomly divided into 12 groups of 12 birds (4 dietary treatments × 3 replicates).

3. A 2 × 4 factorial design was used to study the effect of 2 lines (Factor A) and substitution of soybean meal (SBM) with 4 concentrations (0, 10, 15 and 20%) of sunflower meal (SFM) [Factor B] on egg quality traits of dwarf dam line hens.

4. All the diets were designed to be isocaloric (11?3 MJ ME/kg) and isonitrogenous (180 g/kg crude protein) The duration of the experiment was 12 weeks.

5. Analysis of variance indicated a highly significant line effect. There were non-significant effects of substitution of soybean meal with different concentrations of sunflower meal on egg quality traits except for Haugh unit.

6. White plumaged dwarf broiler breeder dam line produced significantly fewer, but larger, eggs than coloured dwarf dam line hens.     

Implementing poultry vaccination and biosecurity at the village level in Tanzania: a social strategy to promote health in free-range poultry populations

A social strategy was tested for implementing Newcastle disease (ND) vaccination and biosecurity improvements among free-ranging chicken at village level in Tanzania. In addition to training the local poultry vaccinators, data recorders and poultry-keepers, the strategy involved training and empowering leaders at the district, ward and village level. The trainings covered poultry health, management, and marketing of village chickens, with an emphasis on ND vaccination and improving biosecurity against avian influenza (AI), The study sites included villages in one ward in each of three each three districts (Iringa, Mtwara-Mikindani, and Mvomero) of mainland Tanzania. Ninety-six local leaders at district level and 101 leaders at ward levels were trained. In addition, 196 farmers (households) were trained, as well as 86 vaccinators and 26 data recorders. Data recorders were also trained as poultry first aid workers. ND vaccination was conducted by the vaccinators, supervised by their local leaders with technical assistance from veterinarians. A total of 158,343 village chickens were vaccinated in three rounds of vaccination three months apart. The training and empowerment of local leaders and local implementers was the key element for success as it fostered the feeling of local ownership of the program and prevented conflicts with other development activities within the villages. We conclude that most animal health programs will increase their odds of success by involving local leaders and by addressing the current challenges facing the farmers. Further assessment on the usefulness of this approach is needed.     

Differential effects of the endocrine-disrupting compounds bisphenol-A and octylphenol on gonadotropin secretion, in prepubertal ewe lambs

This study examined the effects of long-term exposure to the endocrine-disrupting compounds (EDCs) Bisphenol-A (BPA) and Octylphenol (OP) on gonadotrophin secretion in pre-pubertal female sheep. Four-week-old, female lambs were randomly allocated to four groups (n=6), and twice each week treated with i.m. injections of either corn oil (vehicle controls), diethylstilbestrol (DES; 0.175mg/kg), BPA (3.5mg/kg) or OP (3.5mg/kg). After 5 weeks of treatment, animals were ovariectomized (ovx) and ovary weights recorded. Two weeks later, blood samples were collected from lambs every 15min for 6h, for LH pulse analysis. Animals were then euthanased and adrenal and kidney weight recorded. An age-related increase in tonic LH secretion was noted in Control, BPA- and OP-treated lambs, but was absent in DES-treated lambs. Following ovx, LH secretion increased in all except DES-treated lambs; FSH concentrations increased in all groups. BPA and DES significantly suppressed LH pulse frequency (C: 6.7+/-0.3pulses/6h, DES: 1.5+/-0.8pulses/6h, BPA: 2.3+/-0.8pulses/6h) and amplitude (C: 7.1+/-1.0ng/ml, DES: 1.9+/-0.6ng/ml, BPA: 1.6+/-0.4ng/ml). OP had no effect on LH secretion (Frequency: 5.8+/-0.5pulses/6h, amplitude: 8.0+/-2.0ng/ml). Ovary weight was similar among all groups. Results show that chronic in vivo exposure of prepubertal female lambs to BPA, at levels lower than those reported previously, can have significant effects on LH secretion that are comparable to those seen following exposure to the known xenoestrogen, DES. Exposure to an equal dose of the EDC OP, over the equivalent period of time was without effect on gonadotropin secretion in the prepubertal ewe lamb. These results indicate that exposure of prepubertal female lambs to the EDC BPA can induce significant effects on gonadotropin secretion, the potential long-term effects of exposure and the effects of these changes on reproductive performance and efficacy, therefore, merit further study.     

The Effects of Trypanosomosis on Sperm Morphology in Zebu×Friesian Crossbred Bulls

Detailed studies of sperm morphological abnormalities were carried out on 12 Zebu x Friesian crossbred bulls used in a study of the effects of trypanosomosis. Four bulls were infected with T. vivax, another four with T. congolense, while four served as controls. The infected bulls developed chronic trypanosomosis. All the bulls initially had very low sperm morphological abnormalities that were within acceptable limits for fertile animals. After infection there was a rapid and progressive increase in all sperm abnormalities. Spermatozoa of infected bulls were highly deformed with multiple morphological defects. Mean percentage pre-infection baseline values prior to infection for acrosomal, sperm-head, detached heads, proximal cytoplasmic droplets, distal cytoplasmic droplets, sperm-tail, midpiece and total sperm morphological defects ranged between 0.1 +/- 0.1 for acrosomal and 8.3 +/- 3.2 for total morphological abnormalities in the semen of the bulls. All the infected bulls developed sperm morphological abnormalities of more than a mean of 40.0% from the 4th week after infection until the end of the investigation and were considered unfit for breeding. At 7 weeks post-infection (PI) until the end of the study (12 weeks PI), the controls had a mean of less than 5% sperm morphological defects, while the infected bulls had 100%. Mean percentage values of sperm morphological defects throughout the duration of the investigation for control bulls were low and within the normal range for fertile bulls. These values differed significantly (p<0.001) from the elevated values of the infected bulls. The results show that trypanosomosis due to T. vivax or T. congolense infection can render Zebu x Friesian crossbred bulls unfit for breeding within a very short time. The resultant infertility could be of economic importance in trypanosomosis-endemic sub-Saharan Africa where Zebu x Friesian crossbred bulls are kept.     

Distribution and Activity of Fatty Acid Amide Hydralase (FAAH) in the Gastrointestinal Neurons of Mouse

The endocannabinoid anandamide may regulate intestinal motility through activation of CB1 receptors. Anandamide is then inactivated by fatty acid amide hydrolase (FAAH), a membrane bound enzyme. Under pathological conditions, inactivation of such enzymatic activity may lead to inhibition of the intestinal motility. Here, preliminary reports on the distribution of Fatty Acid Amide Hydrolase (FAAH) immunoreactivity in the mouse gastrointestinal neurons, and the pharmacological effects of N‐arachidonoylserotonin (AA‐5HT), a selective inhibitor of FAAH, are reported. FAAH was revealed by an indirect immunofluorescence. Laminar preparations containing the myenteric or the submucous plexus adhered, were peeled off after the whole gut wall had been stretched out and fixed in 4% paraformaldehyde. They were subsequently incubated with a polyclonal anti‐serum directed against a region near the N‐terminus of the human FAAH and revealed by a FITC‐conjugated goat anti‐rabbit secondary anti‐serum. FAAH‐immunoreactive neurons were observed within the myenteric ganglia throughout the GIT. The positive nerve cells varied in size and density of immunoreactivity. Stomach and large intestine showed the highest neuronal density. AA‐5HT significantly reduced both gastric emptying and gastrointestinal tract transit. Such inhibitory effect was reduced by the C1 receptor antagonist SR141716A. Both morphological and pharmacological results suggest that FAAH may play a critical role in controlling gut anandamide levels.     

The sequential appearance of sperm abnormalities after scrotal insulation or dexamethasone treatment in bulls.

Scrotal insulation and dexamethasone treatment were used as a model to compare the effect of testicular heating and stress on spermatogenesis. Insulation was applied to the scrotum of eight bulls (insulated) for a period of four days, eight bulls were treated daily for seven days with 20 mg dexamethasone injected intramuscularly, and four bulls were untreated controls. Semen from four bulls in each group was collected and evaluated over a six-week period after treatment. Blood samples for testosterone analysis were taken hourly for eight hours at the beginning and the end of the six-week period from the control bulls and before and after treatment from the four insulated and four dexamethasone-treated bulls that were not used for semen collection. At the end of the last blood sampling period, the four bulls in each group were castrated for the collection of testicular tissue for the determination of testosterone concentrations. Basal, peak episodic, and mean serum testosterone concentrations among control bulls, pre and postinsulated bulls, and pretreatment samples of dexamethasone-treated bulls were not different (p > 0.05); however, bulls that had received dexamethasone treatments had significantly lower basal, peak episodic, and mean testosterone concentrations (p < 0.05). Tissue concentrations of testosterone in control, insulated, and dexamethasone-treated bulls were not significantly different but tended to be lower in dexamethasone-treated bulls (p > 0.13). The spermiograms of the control bulls varied insignificantly over the six-week sampling period; however, there was a marked increase in sperm defects in insulated and dexamethasone-treated bulls. The types of sperm defects and the temporal relationships of rises and declines of sperm defects were quite similar for both treatments. All bulls recovered to approximately pretreatment levels of sperm defects by six weeks after the initiation of treatment. Results indicate that two of the most common types of insults to spermatogenesis in bulls, heat and stress, result in similar spermiograms.