Reproductive performance and wastage in Goats in arid and semi arid areas of Kenya with special emphasis on pre-weaning mortality

MSc

This thesis records the results of a study on the reproductive performance and wastage (reproductive efficiency) in indigenous goats in arid and semi-arid areas of Kenya, with special emphasis on pre-weaning mortality. The study can be broadly divided into 3, including an initial slaughterhouse and field survey and an on-farm and on-station study. In the slaughterhouse survey reproductive tracts from both pregnant and non-pregnant does were collected over a I 12 month period from a local slaughterhouse in Dagoretti, Nairobi and data on pregnancy, ovarian activity and genital tract pathologies recorded. The field survey was undertaken in 14 purposefully selected goat producing districts over a 4 year period. During each field visit appropriate samples were obtained, the flocks scored and a questionnaire seeking information on salient features of biophysical characteristics of the study areas and goat production was administered. The on-farm study, which was undertaken in 4 districts over a three year period, was aimed at establishing reproductive efficiency in goat flocks, with emphasis on economics of veterinary intervention and elucidating the factors determining the development of gastroenteritis. To complement the on-farm study and, better understand the events of the early and delayed postnatal period that influence the viability of the kids born of vaccinated and non-vaccinated does were studied more closely. From the slaughterhouse study, a clear pattern of ovarian cyclicity was observed with peak ovarian activity being between February (25%) and May (27%). This pattern was reflected in the two kidding peaks observed during the field and on-farm studies. Of the 461 organs examined loss of conceptus, (maceration and mummification), made up less than 1% of the organs, whereas early embryonic death (EED), ranged between 4-25%, being highest in August (25%). Chronic purulent endometritis (pyometra), congenital malformations, structural abnormalities and functional infertility (cystic ovaries) were only occasionally encountered «2%). Uterine and vaginal swabs prepared from the slaughterhouse organs or parturient does showed that the does' genital tract postpartum may be contaminated with a wide range of bacteria including g. coli, Proteus sp. Pseudomonas sp., Streptococcus sp., Bacillus sp. and ~. aureus. In comparison to cytology, however, positive bacteriology was considered to be a poor indicator of genital infection. Producers and Departments of Animal Production and Veterinary Services personnel listed trypanosomosis, brucellosis, contagious caprine pleuropneumonia (ccpp) /pneumonia and a co-infection of streptothricosis and mange to be the main causes of abortion and infertility in does. They also listed hyperkeratinization of the scrotum with generalized alopecia due to either streptothricosis, mange, or trichophyton infection, physical testicular injuries, brucellosis, lameness and weakness after drought or trypanosomosis and orchitis of unknown etiology as the major causes of buck infertility. The results of the clinical examination and serological screening, on the other hand, indicated that rift valley fever, leptospirosis, besnoitiosis and trypanosomosis, mainlydue to T. vivax and T. congolese, in that order, though not listedby most respondents, were widespread. The causes of postnatal losses identified during the field, on-farmand on-station studies and those reported by the Sheep and Goat Multiplication centres were similar differing only in the ranking. The causes included kids born weak and are unable to suckle (secondary starvation) , gastroenteritis, pneumonia, helminthosis, flea, mange and lice infestation and fungal infections, heartwater and trypanosomosis. Parity and season of birth were the most important variables influencing the rate of postnatal deaths. The veterinary intervention package instituted during the on-farm study, at cost of between Ksh. 14.10-35.80 and Ksh. 24.55-439.90 /kid/season, reduced preweaning kid mortality to ~5%- (range 5-10%-). Based on these results the intervention was considered to have been cost effective, practical and adaptable. Of the kids confirmed, during the on-farm study, to have gastroenteritis characterized by diarrhoea, enteropathogenic E. coli, Streptococcus sp. and Staphylococcus sp. were the most frequent isolates. In comparison several bacteria species, includingE. coli , Pasteurella sp., beta haemolytic Streptococcus, Q. aureus and Proteus sp. were isolated from 15 lung samples from kids that had died of pneumonia during the on-farm and on-station studies. Similar isolates, mainly~. aureus, ~. pyogenes and beta haemolytic Streptococci, were isolated from udder secretions, (milk/pus), obtained from does with mastitis during the field and on-farm studies. Stress and external parasitic infestations were considered to be the most important determinants of postnatal respiratory and gastrointestinal infections. In the present study no virus (es) or mycoplasma were isolated or observed on negative stained preparations from cases of gastroenteritis or pneumonia. In the first three days postpartum serum IgG levels in vaccinated does ranged between 18,000 and 19, OOOmg/l, while the levels in colostrum, which were significantly higher, (P<O.05), ranged between 5,320 and 53,OOOmg/l. The levels in sera from non vaccinated does ranged between 6,000 and 19, OOOmg/I, while the levels in colostrum, which were significantly higher, (P<O.05) , ranged between 4,000 and 45,OOOmg/l. The levels of IgG in colostrums of both groups fell to less than 25% by the third day postpartum. Only traces of IgA were detectable in serum, colostrum and milk obtained from does during the on-farm and on-station studies. Blood parameters of kids born of both vaccinated and non vaccinated dams before suckling were: a total protein (TP) of 36- 59.0g/1, a packed cell volume (PCV) of 29-41%, a haemoglobin (HB) concentration of 10-13 mmol/l, a white cell count (WBC) of 2,500- 7,800, while 19A, 19G and g. coli antibodies were not-detectable. At 12 hours postpartum kids born of vaccinated and non-vaccinated dams had 19,460± 7,479.72mg IgG/l and ~. coli antibody titre of •1/160-1/640, and 22,346.67± 7,885.70mg IgG/l and ~. coli antibody of about 1/160 respectively. Blood parameters of kids in categories 3 and 4 righting reflex remained at the pre-suckling stage and they died in early postnatal period. At 2 weeks of age kids had an a~erage TP level of 60.03± 6.9g/l (range 50.0-73.0g/l), IgG level of 41,460±10,061mg/l (range 26,OOO-56,OOOmg/l) and an ~. coli antibody titre of 1:640 to 1:5,160. Only traces of IgA were observed in the same sera samples. At four weeks of age the TP and IgG levels in sera fell by about 10% while ~. coli antibodies were undetectable. There were no significant differences (P >0.05) in the TP and IgG levels in sera obtained from male and female kids. The levels of TP and IgG and ~. coli antibody titre attained in serum after the eighth week of age were similar to those found in a pooled serum sample obtained from 5 pregnant dams. Blood glucose levels at birth in under weight twins (800 and 900~), were <2.0mmol/l while those of surviving twins and single kids were 4.9 and 5.3mmol/l. The levels of glucose in the underweight kids remained low till death and were closely related to the righting reflex. In the present study the righting reflex, weight at birth, rectal temperature and blood parameters including TP, WBC and blood glucose levels at birth were found to be good prognostic indicators of kid viability. These prognostic indicators and the producer's production objectives and resource allocation priorities need to be assessed before an intervention package is instituted