Abstract: The effect of observational learning on the acquisition of an operant response was examined in eighteen riding horses and ponies. The test horses were randomly divided into three groups of six and individually exposed to one of three treatments. An additional horse was trained as a demonstrator, to perform the operant response. The observer horses watched either the demonstrator performing the bin-opening response (Group D+B); the demonstrator standing passively (Group D); or the operant bin in the absence of the demonstrator (Group B). Observers had access to and were free to interact with an identical bin during testing. Observers in Groups D+B and D were socially familiar with the demonstrator. Each test horse was tested once a day for 10 days. An ANOVA revealed no significant differences between treatment groups in the number of responses or the time taken to reach the learning criterion. However, there were highly significant differences between breed types, with non-warmbloods performing more bouts of opening the bin and feeding (p=0.02), feeding from the bin sooner (p=0.01) and reaching the criterion for learning sooner than warmbloods (p=0.05). There was also a significant negative linear relationship between horses' ages and time spent investigating the bin, with younger horses performing more investigative behaviour (y=-3.08x+106.86; p=0.02).

Abstract: Management practices, stocking rate and flock size may affect laying hen welfare but there have been few replicated studies in commercial non-cage systems that investigate this. This study used a broad range of physical and physiological indicators to assess the welfare of hens in 36 commercial flocks. Six laying period treatments were examined with each treatment replicated 6 times. It was not possible to randomly allocate treatments to houses, so treatment and house were largely confounded. Three stocking rates were compared: 7 birds/m(2) (n = 2450), 9 birds/m(2) (n = 3150) and 12 birds/m(2) in either small (n = 2450) or large (n = 4200) flocks. In addition, at 12 birds/m(2), in both small and large flocks, birds were subjected to either standard (SM) or modified (MM) management. MM flocks had nipple drinkers and no nest-box lights. Bone strength, fracture incidence, heterophil:lymphocyte (H:L) ratio, live weight, organ weights, serum creatine, serum osmolality, muscle pH and faecal corticosterone were measured on samples of birds at the end of the rearing period and at the end of lay. During the laying period, mortality, production and integument condition were recorded at regular intervals. Birds housed at 9 birds/m(2) had higher mortality than birds housed at 12 birds/m(2) by the end of lay, but not higher than birds housed at 7 birds/m(2). Birds housed at 7 and 9 birds/m(2) had lower percent liver weight, and worse plumage condition than most of the 12 bird/m(2) treatments. Modified management tended to improve plumage condition. There were no clear effects of flock size on the welfare indicators recorded. At the end of the rearing period fracture incidence was almost negligible and H:L ratio was within a normal range. By the end of lay fracture incidence was 60% and H:L ratio was high, with no treatment effect for either measure. This, together with information on faecal corticosterone, feather loss and mortality, suggests that the welfare of birds in all treatments was relatively poor by the end of lay.

Abstract: Stereotypies are invariant and repetitive behaviour patterns that seemingly have no function, which tend to develop in captive animals faced with insoluble problems and may be indicative of reduced welfare. A 4 year prospective study of the factors influencing the development of stereotypic and redirected behaviours (abnormal behaviour) in a population of 225 young Thoroughbred and part-Thoroughbred horses was conducted between 1995 and 1999. Abnormal behaviour affected 34.7% of the population. Multivariable analysis showed that foals of low- or middle-ranking mares were less likely to develop abnormal behaviour than foals of dominant mares (rate ratio (RR) 0.23, P<0.01; RR 0.48, P<0.01, respectively). Weaning by confinement in a stable or barn was associated with an increased rate of development of abnormal behaviour, compared with paddock-weaning (RR 2.19, P<0.05), and housing in barns, rather than at grass after weaning, was associated with a further increase (RR 2.54, P<0.01). Specific stereotypic and redirected behaviours were then considered as separate outcomes. Crib-biting was initiated by 10.5% of horses at median age 20 weeks, weaving by 4.6% of horses at median age 60 weeks, box-walking by 2.3% of horses at median age 64 weeks and wood-chewing by 30.3% of horses at median age 30 weeks. Wood-chewing developed at a lower rate in horses born to subordinate or mid-ranking mares than in horses born to dominant mares (RR 0.29, P<0.01; RR 0.41, P<0.01, respectively), and at a higher rate in horses kept in barns or stables rather than at grass after weaning (RR 4.49, P<0.001; RR 1A6, P<0.001, respectively). Feeding concentrates after weaning was associated with a 4-fold increase in the rate of development of crib-biting (RR 4.12, P = 0.02). The results of this study support the idea that simple changes in feeding, housing and weaning practices could substantially lower the incidence of abnormal behaviour in young horses.

Abstract: Nitric oxide (NO) production increases with age in the lupus-prone MRL/lpr mouse, paralleling disease activity. One mechanism for excess NO production in MRL/lpr mice may be a defect in down-regulatory mechanisms of the iNOS pathway. A potential modulator of NO is the nuclear hormone receptor peroxisome proliferation activated receptor gamma (PPARgamma). We demonstrate that renal PPARgamma protein expression was altered as disease progressed in MRL/lpr mice, which paralleled increased iNOS protein expression. Additionally, MRL/lpr-derived primary mesangial cells expressed less PPARgamma than BALB/c mesangial cells and produced more NO in response to LPS and IFNgamma. Furthermore, PPARgamma activity was reduced in mesangial cells following exposure to inflammatory mediators. This activity was restored with the addition of a NOS enzyme inhibitor. These results indicate that the activation of inflammatory pathways may lead to reduced activity and expression of PPARgamma, further exacerbating the disease state.

Abstract: Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor that mediates the antidiabetic effects of thiazolidinediones. PPAR gamma is present in adipose tissue and becomes elevated in fatty livers, but the roles of specific tissues in thiazolidinedione actions are unclear. We studied the function of liver PPAR gamma in both lipoatrophic A-ZIP/F-1 (AZIP) and wild type mice. In AZIP mice, ablation of liver PPAR gamma reduced the hepatic steatosis but worsened the hyperlipidemia, triglyceride clearance, and muscle insulin resistance. Inactivation of AZIP liver PPAR gamma also abolished the hypoglycemic and hypolipidemic effects of rosiglitazone, demonstrating that, in the absence of adipose tissue, the liver is a primary and major site of thiazolidinedione action. In contrast, rosiglitazone remained effective in non-lipoatrophic mice lacking liver PPAR gamma, suggesting that adipose tissue is the major site of thiazolidinedione action in typical mice with adipose tissue. Interestingly, mice without liver PPAR gamma, but with adipose tissue, developed relative fat intolerance, increased adiposity, hyperlipidemia, and insulin resistance. Thus, liver PPAR gamma regulates triglyceride homeostasis, contributing to hepatic steatosis, but protecting other tissues from triglyceride accumulation and insulin resistance.