Association of managemental factors of discrete nature with prevalence of
Cryptosporidium spp. in dairy calves and their analysis is indicated in Table 1.
General farm management practices
In dairy calves prevalence of
Cryptosporidium spp. infection as per farm size was observed to be 24.9 per cent in large farms (100-1000 animals) and 3.74 per cent in medium size (30-100 animals) farms. Risk ratio suggested that the calves of large dairy farms were at 1.96 time’s higher risk for cryptosporidiosis than those reared in medium sized farm. Several scientists have traced an interrelation between sizeable farms and the risk of infection
(Garber et al., 1994; Quigley et al., 1994 and
Mohammed et al., 1999). Garber et al., (1994) found higher prevalence in large (>200 dairy cows) and medium (100-200 dairy cows) herds than in small (<100 dairy cows) herds. Large herds were significantly more likely to have
Cryptosporidium infected calves than were small herds. It is possible that large herds may have a greater density of animals with heavier pathogen load. As a consequence of greater density it may not be possible to prevent continual accumulation of occysts in the environment with less time of cleaning. High stocking rate (8-10 animals/200 sq.ft) and confinement in close proximity might predispose the susceptible young calves to cryptosporidial infections
(Mitchell et al., 1997).
The prevalence of cryptosporidiosis in calves was assessed in relation to farming system (intensive and semi-intensive). Higher prevalence was found in calves of intensive (27.7%) than semi-intensive farming system (0.99%). The farms with intensive farming system were at 1.86 time’s greater risk than those reared under semi-intensive farming. It may be explained by the fact that intensive indoor rearing is usually associated with poor hygiene and thus may contribute to heavy infection. However, it depends on the previous history of infection and the husbandry management involved.
Animals drinking ground water had higher prevalence (27.7%) of
Cryptosporidium spp. oocysts in faecal samples as compared to animals drinking tap water supplied by municipality (0.99%). Statistically it was noted that at 95% CI (confidence interval) the value of odd ratio between animals using ground water versus tap water for drinking was 1.86. Therefore, it was inferred that the farms using ground water for drinking were nearly two times more prone for
Cryptosporidium spp. infection than those using tap water for drinking. Our findings are in accordance with that of
El-Khodery and Osman (2008) who found that calves drinking water from wells or underground water were at higher risk of infections than ones consuming tap water (OR=0.268; CI 95%:0.246-0.913) and it may be ascribed to contamination of underground water with sewage. Oocysts of
Cryptosporidium spp. were found in agricultural run-off water and its outbreak in humans has been assigned to using contaminated water for drinking and bathing
(Fayer, 2004). There is a possibility of
C.
parvum oocysts percolating through soil layer in areas where cow manure fertilizer is used.
The prevalence of
Cryptosporidium spp. was significantly (p<0.05) higher (16.7%) in farms where level of cleanliness was found to be ‘dirty’ (floor of the farms was not clean regularly) as compared to ‘clean’ farms (floor of the farm was clean regularly) (11.6%). The risk of occurrence of cryptosporidiosis in a dirty farm was nearly twice (OR=1.90) than clean farm. Similar to present finding,
Swai and Schoonman (2010) recorded higher risk of exposure and infections with
Cryptosporidium spp. in calves who slept on dirty floors than the ones on moderate to clean floors (OR=1.82).
The presence of other animals like dog, birds at farm changed the prevalence of cryptosporidiosis in dairy calves. The prevalence was higher (15.9%) in farms with other species like dog, birds were reared alongside as compared to farms with no other species of animal being reared. (12.7%). The risk of infection in farms with other animals reared along (dogs, birds) was also found to be higher (OR=1.36). However, non-significant association was found. These results are in accordance with those reported by
Muhid et al., (2011) who reported higher prevalence and risk (OR=1.5) in farms where other animals were present.
In the farms where regular deworming of animals with albendazole and fenbendazole was done, the prevalence of
Cryptosporidium was significantly (p<0.05) lower (13.9%) than those who were not dewormed at regular interval (14.7%). The chances of infection were five times higher (OR=5.09) in farms without regular deworming practices.
Muhid et al., (2011) determined significant association between
Cryptosporidium spp. infection and anti-helmintic treatment. The calves which were dewormed regularly had less chances of infection (OR=0.28) than the ones dewormed less regularly. A lower (12.5%) prevalence was observed in farms where treatment of diarrhoeic calves was practised as compared to farms where no treatment for diarrhoea was done (16.2%). The risk of infection was almost similar in both type of farms (OR=1.07).
Trotz-Williams et al. (2008) found significant association between prevalence of
Cryptosporidium spp. infection and use of prophylactics against calf scour (RR=1.38). Similarly,
Muhid et al., (2011) reported that the calves that were treated thrice with antibiotic and anti-diarrhoeal drugs in a year had less chances of infection (OR=0.28).
Calf management practices
Calves born in common calving penhad higher prevalence of
Cryptosporidium spp. oocysts in faecal samples (27.7% vs. 0.99%) as compared to calves born in individual calving pen. The odd ratio indicated nearly two times higher (OR=1.86) chance of infection in prior than latter. The results coincide with that of
Garber et al., (1994) who observed that farms with multiple cow maternity facilities were more likely to have calves with
Cryptosporidium spp. infection than those farms with individual facilities.
Post-parturient dams and hutches contaminated with oocysts from previous calf may act as source of
Cryptosporidium spp. infection to dairy calves
(Maldonado-Camargo et al., 1998). Cryptosporidia oocyst may also be present in the maternity area from sources other than neonatal calves such as; rodents, cats, human beings or equipment. Therefore, the prevalence of calf cryptosporidiosis in the present study was assessed in relation to the cleaning of calving pens before parturition. It was observed that calves born in dirty calving pens had greater prevalence (15.2% vs. 13.4%) of
Cryptosporidium spp. Infection. These calves are 1.41 times more prone for the infection than those born in clean calving pens.
Garber et al., (1994) opined that cryptosporidiosis was not associated with whether or not the maternity area was cleaned. Survival of
Cryptosporidium oocysts is affected by temperature, ammonia concentration, pH
(Reinoso et al., 2008) and the floor type is likely to cast an effect on these factors. Thus the impact of floor type of calving pen on
Cryptosporidium spp. infection was assessed and it was found that the prevalence was higher (27.7%) in calves born on concrete/cemented floor calving pen as compared to earth floor calving pen (0.99%). The risk of infection in calves born in calving pen with concrete/cemented floor was nearly two times higher (OR=1.86). The findings of our study may be biased as majority of the selected farms were having concrete floors. Similar to our findings,
El-Khodery and Osman (2008) observed that type of flooring had a prominent effect on prevalence of cryptosporidiosis on farms and recorded higher risks associated with cemented floors than earthen floors (OR=2.22; CI 95%:1.340-7.32), it could be possible due to retention of moisture and providing favourable conditions for greater prevalence.
Maddox-Hyttel et al. (2006) suggested that
Cryptosporidium infections or its excretion in faeces were decreased by the use of straw and deep litter system and this finding was attributed to the microclimatic factors which govern oocyst survival.
The effect of sweeping of floor on the prevalence of calf cryptosporidiosis was also observed. The prevalence was found to be lower (12.5%) in farms where floor was swept daily than where the floor was not swept daily (16.2%). Odd ratio indicated that if sweeping is not done daily at farm, the risk of infection may be higher (OR=1.23).
Castro-Hermida et al. (2002) observed a significant difference between the effect of monthly and daily cleaning (OR: 1.8; CI 95%: 1.1-3.1); the risk of getting infection was increased by 87.0% in calves whose pens were cleaned monthly than calves whose pens were cleaned daily (OR: 1.9; CI 95%: 1.3-2.9).
El-Khodery and Osman (2008) also reported that calves tend to have less chances of getting infection whendaily cleaning of shed is done rather than reared in sheds that were cleaned weekly (OR=6.625; CI 95%:2.489-17.631).
The prevalence of cryptosporidiosis was lower (13.4%) in farms where calves received colostrum within one hour of birth as compared to farms where calves were not fed colostrum within an hour (15.2%). The odd ratio indicated that the chance of cryptosporidiosis was 1.41 times higher in calves that do not receive colostrum within hour after birth. This is explained by the protecting mechanism of colostral and milk antibodies whereby they block parasitic invasion and immobilize the gut luminal parasitic form, this protects calves from displaying severe clinical signs
(Mohammed et al., 1999). El-Garhy, (1982) stated that calves were hypogammaglobulinaemic at birth and must obtain immunoglobulins (Ig) during the period of macromolecular transport within the first 24 h of life. So, it is advisable to offer an adequate amount of colostrum in the early period after birth to protect them from the infectious disease during the neonatal period.
The prevalence of cryptosporidiosis was associated with the time of weaning. Analysis revealed that the prevalence was lower in farms where calves were weaned within 24 hours (0.49% vs. 28.2%). Odd ratio indicated that the risk of infection was two times higher (OR=2.05) in calves not separated from dam within 24 hours of calving. Our results coincide with that of
Wu et al., (2010) who recorded that the prevalence of
Cryptosporidium spp. on farms where calves were immediately isolated into individual pens was significantly (p<0.05) lower (50.0%) than that of the farms which isolated the neonatal calves between second to tenth day after birth (85.0%). This suggested that calves are most susceptible to infection with
Cryptosporidium spp. shortly after birth and that infection spreads rapidly
(McCluskey et al., 1995; Quilez et al., 1996 and
Tortz-Williams et al., 2007).
The infection was significantly (p<0.05) higher in farms where the calves were confined with their mother (17.2% vs. 11.5%) and such calves were at five times higher (OR=5.20) risk of infection. The findings of present study are in accordance with the findings of
Quigley et al., (1994) and
Mohammed et al., (1999) who discerned a lowered infection risks in calves which were separated from their mothers within few hours of birth and fed manually.
El-Khodery and Osman (2008) reported non-significant (p>0.05) effect of calf separation from the mother on the disease prevalence.
The prevalence of cryptosporidiosis was lower (3.2%) in farms where the calves received colostrum @ 10% body weight/day as compared to their counterparts (25.4%). Risk ratio suggested that the chance of occurrence of
Cryptosporidium spp. was 1.87 times higher in calves which did not receive colostrum @ 10% body weight/day. The value of adequate colostrum consumption by calves and its effect on calf health is well admitted. Hence, intake of inadequate colostrum (low concentration of IgG) could elevate the infection risks in calves.
Cryptosporidium spp. infection was lower (2.5%) on the farms which used detergent to wash feeding utensils as compared to those where detergent was not used (26.2%). Risk ratio of infection was 1.51 times higher at farms not using detergent. Similar to our results
Trotz-Williams et al. (2008) found that washing calf feeding equipments with soap or detergent had safeguarding effects and significantly associated with a decreased prevalence.
