Influence of oral lead administration on rumen fermantative develoment in pre-ruminent calves

Abstract

Depending upon the dose and duration of lead exposure, the spectrum of biological response may range from overt clinical signs referable to nervous, gastrointestinal and haemopoietic systems to subclinical subtle effects (Swarup 1996). Amongst the various lead induced pathological effects, disturbances in gastrointestinal functions (Upadhyaya and Swarup 1990, Dey et al. 1996) and the adverse effect on mineral metabolism (Bebe and Panemangalore 1996, Patra et al. 2001) suggest a possible toxic effect on rumen microbes resulting in altered rumen fermentation, which may lead to poor nutrition and production performances in ruminant livestock particularly the growth of calves, which are highly susceptible. It is further hypothesized that toxicity to ruminal flora will be a major impediment to rumen development and adversely resulting into future heifer/bull production. The present investigation was carried out to study the influence of orally administered lead on rumen fermentative characters in pre-ruminant calves as an indicator of rumen development. Healthy male calves (10), 25 to 35 days old and with average body weight of29.2 kg, were randomly distributed into 2 groups of 5 each. They were fed whole milk plus calf starter and cereal green fodder. The calf starter was constituted of ground maize 40%, wheat bran 30%, deoiled groundnut cake 27% and mineral mixture and salt 3%. Five calves were administered 0.75% aqueous solution of 99%- pure lead acetate @ 1 ml/kg body weight (equivalent to 7.5 mg oflead acetate or 4.097 mg lead) orally for 21 days. Group of another 5 calves received no treatment and served as unexposed healthy control. Blood samples were collected from jugular venepuncture from all the animals prior to and on day 21 post-exposure to lead to analyze blood lead concentration. Blood samples (approximately 5 ml) were collected in nitric acid washed heparinized vials and wet digested with nitric acid and perchloric acid mixture (Kolmer et al, 1951). The concentration of lead in the digested sample was estimated using atomic absorption spectrophotometer at the wavelength.