Effects of season on the reproductive organ and plasma testosterone concentrations in guinea cocks (Numida meleagris).

The physiological basis of seasonal breeding in the guinea fowl (Numida meleagris) still remains unknown, despite the socioeconomic importance of these birds, particularly in Ghana. A study involving a total of 50 local guinea cocks was conducted, and documented gross anatomical and histological differences in the reproductive organs of breeding and non-breeding male guinea fowls. The study also compared peripheral testosterone concentrations in breeding and non-breeding cocks. Seasonal differences in variables measured were determined using two-tailed t-test/Mann-Whitney U-test. All comparisons were made at 5% level of significance. Breeding males had significantly (P = 0.000) higher anatomical biometric parameters than their non-breeding counterparts. Also, breeding birds had thicker (P = 0.000) phalli than their non-breeding counterparts. Histologically, regressing testis was characterized by the presence of sloughed off cells and increased debris in the tubular lumen and within the excurrent duct system, collapsed tubules and reduction in tubular lumen. Germ and Sertoli cell populations and nuclear diameters and actual seminiferous tubular diameter and length in regressing testes were significantly (P = 0.000) lower than in active testes. Leydig cell nuclear diameters and populations were also significantly (P = 0.000) reduced. Relative volume of seminiferous tubules in the testis, testicular sperm production/mg testis and per testis and peripheral testosterone concentrations were all higher (P < 0.05) in breeding than non-breeding testis. The ducts in the epididymal region also saw significant (P < 0.05) reductions in luminal diameters in non-breeding birds. Significant regression in anatomical and histological structures of the guinea cock reproductive tract occurred during the non-breeding season, and lower peripheral testosterone concentrations may be responsible for this phenomenon.

Effects of season on the reproductive organs and steroid hormone profiles in guinea hens (Numida meleagris).

The study documented gross anatomical and histological differences in the reproductive organs of 28 breeding and non-breeding female guinea fowls. Peripheral progesterone and 17ß-oestradiol concentrations were also compared in breeding and non-breeding hens. In non-breeding females, all ovarian and oviducal gross anatomical features had significantly regressed. Histologically, some of the changes in a regressing oviduct include systematic changes in height and size of all epithelial cells in all regions of the duct, absence/sparse ciliation of portions of surface epithelium in the magnum, isthmian and uterine regions, general loss of cytoplasmic mass, reduction in size and degeneration of tubular glands. Mucosal folds in all regions of the oviduct except the infundibular lip were higher in breeding females. No difference was found between the two groups in plasma progesterone concentrations. Breeding females, however, had higher peripheral oestradiol concentrations than non-breeding females. About 2 h prior to oviposition, plasma oestradiol concentrations peaked at 2.4-fold (230 pg/ml) compared with baseline concentration and plasma progesterone concentrations by nearly 9-fold (5.29 ng/ml) of baseline. Significant regression and changes in the histological structure of the ovary and oviduct had occurred in non-breeding females, and lower peripheral oestrogen concentrations may be responsible for this phenomenon.

THE EVALUATION OF DOMESTIC DUCKS AS POTENTIAL RESERVOIR OF AVIAN INFLUENZA VIRUS IN POST HPAI H5N1 OUTBREAK AREA, SUNYANI MUNICIPALITY, BRONG AHAFO REGION OF GHANA.

BACKGROUND: Avian influenza (AI) is an important zoonotic disease responsible for significant losses in most sub-Saharan countries. However, the role of poultry other than chicken in the epidemiology of the disease, especially after the first AI outbreak in Ghana, has not been fully elucidated. The obiective of this study is to determine whether the AI virus infection that was reported in the area in May 2007 was circulating silently in ducks in nine randomly selected farms in the Sunyani Municipality, Ghana. MATERIALS AND METHODS: The sample size was calculated using Epi info version 3.4.1 at 95% confidence level, absolute precision of 5% and assuming 0.5 prevalence of Avian Influenza A virus in ducks. Samples collection was done simultaneously with questionnaire administration to farmers. A total of 526 samples made up of 384 cloacal swabs and 142 feather tissues from ducks from a commercial duck farm, seven backyard holdings and one live birds market in six randomly selected communities in the Sunyani Municipality, Brong Ahafo region of Ghana. The samples were processed and subjected to Influenza Type A Matrix Gene analysis using RRT-PCR. RESULTS: All the 526 samples subiected to Influenza Type A Matrix Gene analysis using RRT-PCR were negative for Influenza Type A viruses. However, it was observed that bio-security practices which are keys to reintroduction of the virus in the area were not adhered to in 89 % of the sites investigated. Our finding also revealed that only the commercial farm investigated in this study complied with fifteen (78.9%) of the nineteen different farm practices observed. CONCLUSION: Though AI was not detected in the ducks sampled, there is the need for continuous surveillance and education of stakeholders on standard bio-security and farm management practices in the area.

Detection of Trypanosoma brucei, T. congolense and T. vivax infections in cattle, sheep and goats using latex agglutination.

A monoclonal antibody-based latex agglutination test for detection of circulating trypanosome antigens in animal serum was evaluated for the ability to detect natural T. brucei, T. congolense and T. vivax infections in cattle, sheep and goats in Ghana. The test detected antigens in 180/422 (42.7%) of cattle, 27/131 (20.6%) of sheep and 14/79 (17.7%) of the goats. By comparison, the microplate-based antigen-ELISA gave similar results (P > 0.01), detecting trypanosome antigens in 41.7% of the cattle, 19.8% of the sheep and 17.7% of the goats. Trypanosomes were demonstrated in the blood of 30 (7.2%) cattle, 7 (5.3%) sheep and 3 (3.8%) goats using the buffy coat technique (BCT). Of these, 26 cattle (86.7%), 6 sheep (85.7%) and all 3 goats (100%) were antigenaemic. The most prevalent single infection in all 3 animal species involved T. vivax, and the most common mixed infection involved all 3 trypanosome species in cattle and sheep. There was no mixed infection in goats. Compared with the antigen-ELISA, the sensitivity of the latex agglutination test was 98.3% in cattle and 100% in both sheep and goats, whilst the specificity was 97.2% in cattle, 99% in sheep and 100% in goats. False positivity with the latex agglutination test was 3.9% in cattle and 3.7% in sheep. There were no false-positive reactions with the test in goats. The latex agglutination assay promises to be ideal for testing small numbers of animals under field conditions.

Seroprevalence of brucellosis in cattle and humans in the Akwapim-South district of Ghana: public health implications.

A total of 183 cattle comprising 54 bulls, 53 milking cows, 76 heifers and 44 calves in the Akwapim-South district of Ghana were tested for antibodies against Brucella abortus using the Rose Bengal plate test. The results indicated that cattle in the Akwapim-South district were infected with Brucella with a mean seroprevalence of 6. 6%. There was no difference in the seroprevalence either between females 11/129 (8.5%) and males 1/54 (1.9%), or among the three different breeds of cattle (Sanga, West African short horn (WASH) and white Fulani) in the study area. However, there was a significant increase in seropositivity with respect to age. A significant association between antibodies against Brucella and a history of abortions and retained placenta in cows indicated that brucellosis might be responsible for significant economic losses to farmers in the area. However, no evidence of human brucellosis was detected by antibody screening in selected risk groups.

An assessment of the safety of street foods in the Ga district, of Ghana; implications for the spread of zoonoses.

Street food refers to food and beverages prepared and sold by vendors in streets and other public places for immediate consumption. In Ghana street foods are sold at small eating places popularly known as 'chop bars'. Food safety studies were conducted on the premises of 160 'chop bars' in the Ga District of Ghana in July 1998. Only three (1.8%) of the proprietors met all the requirements (based on a five-point checklist) for basic hygiene. Twenty-four (15%) out of the 160 proprietors had access to potable water while the other 136 (85%) proprietors purchased water from vendors and six used pond water. These two latter sources of water were of poor microbiological quality (as shown by faecal coliform values which ranged from 1.0x10(2)-1.9x10(5) cfu/ml). One hundred and five proprietors (65.6%) did not obtain their meat supply from an approved source. Factors influencing the purchase of meat from an approved source included the proximity of a chop bar to a slaughter facility, the conduct of meat inspection personnel and affordable user fees.

Embryonic resorption, litter size and sex ratio in the grasscutter, Thryonomys swinderianus.

This study was conducted using 210 whole uteri collected from hunters' kills from July 2006 to March 2007 at Esiam and Sokode in the Ekumfi and Ho Districts respectively; and data on 148 dams from eight farms in the Greater Accra Region of Ghana from January to December 2007. The objective of the study was to investigate the effects of embryonic resorption, litter size and parity on sex ratio in the grasscutter. Embryonic resorption rate, which occurred at all stages of pregnancy, ranged between 41.3% and 47.2%, and was not biased towards male or female offspring. The rate of resorption also had no effect on sex ratio (r=-0.011, P=0.396). The study also showed that litter size in the grasscutter could be improved if embryo resorption is controlled. Primiparous dams had offspring with a sex ratio of 0.43+/-0.020 which was not significantly different from dams of parities 3 (0.47+/-0.040) and > or =4 (0.53+/-0.053). Parity 2 dams, however, had a significantly higher proportion of males (0.54+/-0.024). There was a tendency towards a decreasing proportion of males as litter size increased but the overall sex ratio observed in the farmed grasscutter (0.48) did not deviate significantly from the theoretical sex ratio of 0.50.

Susceptibility of Amblyomma variegatum ticks to acaricides in Ghana.

Abstract. The susceptibility of unfed and fed stages of larvae, nymphs and adult females of Amblyomma variegatum ticks were tested using Shaw's filter paper dip method against four acaricides; chlorfenvinphos and dioxathion, chlorfenvinphos, gamma benzene hexachloride and amitraz at four different concentrations including the recommended dose rates. Based on their lethal concentrations (LC50 & LC90) chlorfenvinphos and dioxathion combined and chlorfenvinphos alone placed first and second, respectively, in all stages except at the unfed nymphal stage where gamma benzene hexachloride topped with a LC50 of 0.001629, while chlorfenvinphos and dioxathion combined and chlorfenvinphos alone had LC50 of 0.001794 and 0.002258, respectively. Amitraz appeared to have a quick knock-down effect on larvae and nymphs but at the recommended dose rate, showed no mortality of the ticks at that stage. However, at a concentration of 0.040%, amitraz showed a 100% inhibition of oviposition and hatching of laid eggs. Gamma benzene hexachloride produced only 66% inhibition of oviposition while chlorfenvinphos and dioxathion combined and chlorfenvinphos alone produced 100% inhibition of oviposition at their recommended dose rates. Fed nymphs were more susceptible than the unfed nymphs. Eggs laid by engorged female ovipositing ticks, applied with gamma benzene hexachloride, hatched.

Acaricides in tick control in Ghana and methods of application.

A wide range of acaricides, including organophosphates, organochlorines, carbamates and synthetic pyrethroids are currently being used on livestock in Ghana. The most widely used acaricide in the country is still the organochlorine Lindane. A number of the products used to control ticks on livestock are designed and imported into the country for use as pesticides on crops. The most popular method of application is by hand dressing. Current methods of application together with the general failure to observe withdrawal period for meat and milk could be considered to constitute a significant human health risk.

Survey of pesticides used in the control of ectoparasites on farm animals in Ghana.

A study to identify the various types of pesticides used on farm animals in Ghana for the control of ectoparasites was conducted in 1989. Eleven organisations involved with pesticide use were questioned. Thirty organised farms and 110 kraals distributed throughout the 10 regions of Ghana were visited. Twenty different pesticides were in use. Of these 45% were organophosphates, 30% were synthetic pyrethroids, 15% were carbamates and 10% organochlorines. The most widely distributed and used pesticide was an organochlorine (lindane), which accounted for 35% of those used on farms and 85% used by herdsmen. The most popular mode of application was by hand dressing. No withdrawal periods before slaughter or sale of milk for consumption were practised. The implications of these findings in the light of possible emergence of pesticide resistance and health hazards are discussed.