Two groups of five sheep (7 months of age) were moved and isolated in pens which did not allow visual and tactile contact with other sheep for 24 h. They were then moved back to their original pens where visual and tactile contact was possible. After 24 h the procedure was repeated seven times for one group (group 8-1) and thirteen times for the other group (group 14-1). One group (control) of five sheep remained in pens where visual and tactile contact was possible. When isolated the lambs spent more time standing still in an alert posture, less time eating and resting, and vocalized more than control lambs. The heart rate of the lambs increased when they were moved between pens and during isolation. The plasma concentration of cortisol was significantly increased after 1·5 h and 3 h of isolation. The plasma concentration of prolactin was increased after 1·5 h of isolation. After 3 h of isolation the number of neutrophils in the blood was increased and the numbers of T-lymphocytes (CD2), T-helper-lymphocytes (CD4) and yd-lymphocytes (T19) were decreased. After 24 h of isolation the lymphocyte blastogenic response to Con A was lower and the numbers of T-lymphocytes and T-helper-lymphocytes were still less than those in control lambs. Although there were still behavioural changes when the lambs were isolated for the seventh time, no cortisol, prolactin and leucocyte changes were found. These results suggest that stressors similar to isolation, which can occur during normal management practice, may elicit short-term leucocyte changes in lambs.

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SummaryFrequency of blood group factors at the A‐O and H loci were markedly altered within halothane positive (HP) and halothane negative (HN) composite synthetic Pietrain/Hampshire lines (PTH) over four generations of selection.Linkage studies on the litters from 45 double backcross and 20 mixed and intercross matings, involving the S(A‐O), H, Phi and Hal loci, were made in the PTH line and halothane positive and negative selected British Landrace lines. Crossing‐over frequencies of 0.05 ± 0.04, 0.05 ± 0.03 and 0.1 ± 0.03 were established between Phi and Hal, H and Hal, and Phi and H respectively. An unequal crossing‐over frequency between Phi and H was found when the alleles Ha and Hcd were compared. The difference in recombination frequency between the Ha and Hcd alleles amounted to 0.04 to 0.06.No cross‐overs were observed between the S(A ‐O) and Phi, H or Hal loci in 15 families studied. The position of the S locus in relation to the other loci could not be established, but statistical evidence of association favours a haplotype sequence of Phi‐Hal‐S‐H.

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The demonstration of a reagin-like antibody against Culicoides pulicaris extract in the serum of horses and ponies affected with recurrent seasonal dermatitis (sweet itch) is reported. This antibody can confer Prauznitz-Küstner (P-K) sensitivity on homologous skin for up to 5 days and, like human IgE, is thermolabile and susceptible to 2-mercaptoethanol reduction. It is eluted on diethylaminoethyl dextran-52 anion exchange chromatography independently of IgG, IgG(T) and IgM, and its elution characteristics indicate similarity in net molecular charge to human IgE. The P-K response observed in horse skin is biphasic, and is morphologically similar to the late cutaneous anaphylactic response in man. Both phases of the P-K response are dependent upon the reagin-like antibody, although other serum factors appear involved in the delayed phase of the response.

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