The study reports the performance of four indirect enzyme-linked immunosorbent assays (ELISAs) for antibody (AB) detection using microtitre plates which were precoated with native or heat/detergent denatured antigens (AGs) from Trypanosoma congolense (T.c.) and T. vivax (T.v.), and stored for between 1 to 206 days at +37 degrees C. Bovine serum samples were obtained by sequential bleeding of 3-months old T.c.-infected bulls and their uninfected cohorts, as well as by a single bleeding of uninfected adult cattle. The first day of AB detection, and observations on samples after this (defined as estimated ELISA sensitivity), depended on the cut-off value in the specific ELISAs. Cut-off values from pre- and early post-infection samples of individual animals demonstrated a seroconversion in all ELISAs on average after 10-15 days post-infection (dpi). The AB detection was delayed in the T.c. native and denatured AG-based ELISAs using cut-off points from uninfected cohort cattle (16.5 dpi, 19.3 dpi) and the adult cattle population (22.1 dpi, 25.0 dpi). The T.v. AG-based ELISAs however lacked crossreactiviy to T.c. ABs. The estimated sensitivity of each T.c. AG-based ELISA was above 96% throughout, but significantly lower for the T.c. native AG-based ELISA (91.1%) when the adult cattle derived cut-off point was used (p<0.01). The sensitivity of the phase contrast buffy coat technique was similar to the T.c. AG-based ELISAs, but significantly lower when the T.c. denatured AG-based ELISA was used at the adult cattle derived cut-off point (p<0.05). The implications of the results and future research aspects on ELISAs to detect trypanosomal ABs and AGs are discussed.

The behavioural response of sows and gilts accommodated in groups of up to 6, in two rooms of farrowing nests was observed at the West Sussex College of Agriculture and Horticulture. A split-plot experiment was carried out at three levels: ( 1 ) room (north/south); (2) season (winter/summer); (3) week of sow occupancy (before and 1, 2 and 3 weeks after parturition ). The sows were grouped according to normal commercial practice with farrowing dates matched as closely as possible. Inevitably sows farrowed in both Weeks 0 and 1. No attempt was made to balance animals for age or behavioural profile. Observations for sow position, posture and activity were recorded every 10 min over 53 4-h periods. Additional data collected included time sows spent out of nests and frequency of feeder visits. Sow performance was assessed from litter data for all sows farrowing in both the nests and a crate system between 1 August and 31 December. (Number of litters= 110. ) The most frequently observed position, posture and activity of the sow was in the nests ( 76% of observations), lying down (67%) and inactive (70%), respectively. Week of sow occupancy had a significant effect on the number of feeder visits made by sows (P < 0.05 ) with more feeder visits being made during the second week. In the north room sows spent a greater proportion of their time in the nests during the winter (95 vs. 64%) but this was not repeated in the south room. There was no difference between nests and crates in number born alive or in number weaned. Survival rate for August was higher for the litters in nests, but there were no differences observed in other months.