Lateralization of behavior in dairy cows in response to conspecifics and novel persons.

The right brain hemisphere, connected to the left eye, coordinates fight and flight behaviors in a wide variety of vertebrate species. We investigated whether left eye vision predominates in dairy cows' interactions with other cows and humans, and whether dominance status affects the extent of visual lateralization. Although we found no overall lateralization of eye use to view other cows during interactions, cows that were submissive in an interaction were more likely to use their left eye to view a dominant animal. Both subordinate and older cows were more likely to use their left eye to view other cattle during interactions. Cows that predominantly used their left eye during aggressive interactions were more likely to use their left eye to view a person in unfamiliar clothing in the middle of a track by passing them on the right side. However, a person in familiar clothing was viewed predominantly with the right eye when they passed mainly on the left side. Cows predominantly using their left eyes in cow-to-cow interactions showed more overt responses to restraint in a crush compared with cows who predominantly used their right eyes during interactions (crush scores: left eye users 7.9, right eye users 6.4, standard error of the difference=0.72). Thus, interactions between 2 cows and between cows and people were visually lateralized, with losing and subordinate cows being more likely to use their left eyes to view winning and dominant cattle and unfamiliar humans.

Pathology of Mycobacterium bovis infection in wild meerkats (Suricata suricatta).

Pathological lesions associated with Mycobacterium bovis infection (bovine tuberculosis; bTB) in free-living meerkats (Suricata suricatta) in the Kalahari Desert of South Africa are described. The pathology of bTB in meerkats was determined through detailed post-mortem examinations of 57 animals (52 meerkats showing clinical signs of bTB, and five not showing signs of disease). Lymph nodes and tissue lesions thought to be associated with bTB were cultured for mycobacteria. All 52 bTB-infected meerkats showed gross or microscopical granulomatous lesions, but M. bovis was cultured from only 42% (22/52) of these animals. The majority (96%, 50/52) of diseased meerkats had lesions in multiple sites, the pattern of which suggested haematogenous spread of M. bovis infection in this species. The histological characteristics of the tuberculous lesions, together with the gross pathology and the wide range of body systems affected, indicate that infection in meerkats is acquired principally via the respiratory and oral routes, whereas excretion is most likely via the respiratory tract and suppurating skin wounds. Urine and faeces appear to be unlikely sources of infection. The findings of this study provide information on the transmission, pathogenesis and epidemiology of bTB in meerkats that is likely to be relevant to the understanding of M. bovis infection in other social mammal species such as the European badger (Meles meles).

Influence of rearing conditions and respiratory disease on haptoglobin levels in the pig at slaughter.

Associations between serum concentrations of haptoglobin, pathological lung lesions indicative of Mycoplasma hyopneumoniae (EP) or Actinobacillus pleuropneumoniae (PL) infection at slaughter and previous rearing environment were investigated in 510 pigs (90-100 kg live weight) from 17 farms in England. Haptoglobin concentrations were significantly higher in pigs showing pathological signs of EP infection compared to those without signs of this disease (EP positive median 0.43 mg ml(-1) vs. EP negative median 0.26 mg ml(-1), p<0.01). However, there were no significant associations between serum haptoglobin concentrations and pathological signs of PL. The presence of solid partitions compared with barred or similar open partitions was associated with a decrease of 0.44 mg ml(-1) farm mean haptoglobin concentration, whilst an increase in pen size of 10 m(2) was associated with a decrease of 0.08 mg ml(-1) farm mean haptoglobin concentration. The findings indicate that pathological signs of EP were associated with increased serum haptoglobin at slaughter, which in turn was influenced by components of the farm environment.

Factors in the housing environment of finisher pigs associated with the development of gastric ulcers.

The prevalence and severity of gastric ulcers were investigated in a sample of 50 slaughter pigs from each of 16 commercial farms in the uk. The mean prevalence of ulcers was 19.1 per cent and the mean (se) severity score on the 16 farms was 2.2 (0.15) on a scale from 0 (normal) to 6 (severe). Multivariate regression analysis showed that the type of lying surface provided for the pigs during the finishing phase was the most important factor associated with the occurrence of gastric ulcers in the farms studied. Finisher pigs housed on slatted floors had a significantly higher mean ulcer severity score (P<0.001) than pigs housed on solid concrete floors, which had a significantly higher score (P<0.01) than pigs housed on straw bedding. Feeding a pelleted finisher ration was also associated with significant increase in ulcer severity (P<0.01) compared with feeding an unpelleted ration, but was of less importance than the type of floor. The detrimental influence of feeding pellets was ameliorated by the provision of straw bedding.

Femoral asymmetry in the Thoroughbred racehorse.

OBJECTIVE: To investigate the occurrence of geometrical asymmetries in the macro-architecture of left and right femurs from Thoroughbred racehorses previously used in competitive training and racing in New South Wales, Australia. METHODS: Detailed postmortem measurements were made of 37 characteristics of left and right femurs from eleven Thoroughbred racehorses euthanased for reasons unrelated to the study. Measurements focused on articulating surfaces and sites of attachment of muscles and ligaments known to be associated with hindlimb locomotion. RESULTS: Five measurements were significantly larger in left compared to right femurs (P < 0.05). The regions showing significant differences between left and right limbs were proximal cranial and overhead medio-lateral widths, greater trochanter depth, depth of the fovea in the femoral head and distal inter-epicondylar width. CONCLUSION: The left-right differences in femoral morphology were associated with sites of muscle and ligament attachment known to be involved with hindlimb function in negotiating turns. These differences may be the result of selection pressure for racing performance on curved race tracks and/or adaptations related to asymmetrical loading of the outside hindlimb associated with repeated negotiation of turns on such tracks.

Epidemiology of enteric disease in grower-finisher pigs: a postal survey of pig producers in England.

A questionnaire was sent to 238 members of local pig discussion groups in the West Midlands region of England to identify farm level factors associated with the occurrence of diarrhoea in grower-finisher pigs. The questions related to the occurrence, diagnosis and aetiology of scour problems on the farm, the prevalence of common porcine diseases on the farm, the classes of pigs, staff employment, source of replacement stock and biosecurity measures, the husbandry techniques such as piglet management, use of medication, movement and mixing of pigs, dung removal and pen preparation between batches of pigs, and the physical resources such as floor type, pen divisions, watering, feeding and dung disposal systems. Replies from 105 producers keeping grower-finisher pigs were included in the analysis, 50.5 per cent of which had had a scour problem at some time in the previous three years. The causes of scour had been identified as colitis (34.3 per cent), swine dysentery (10.5 per cent) or porcine enteropathy (3.8 per cent). There was a significant association between the following factors and the occurrence of diarrhoea in grower-finisher pigs: the use of water medication for weaners (odds ratio = 11.8; P = 0.002), the tail-docking of piglets (odds ratio = 8.6; P = 0.003), the use of a wet feeding system for finishers (odds ratio = 5.9; P = 0.009), finishers housed on partially slatted floors (odds ratio = 3.6; P = 0.044), and the use of an isolation procedure for incoming breeding stock involving exposure to dung (odds ratio = 3.5; P = 0.046). The use of disinfectant in the preparation of pens between batches of pigs appeared to be protective (odds ratio = 0.3; P = 0.046).

Interactions between dietary fibre, endo-parasites and Lawsonia intracellularis bacteria in grower-finisher pigs.

Samples of faeces and feed were collected from grower and finisher pigs kept on 25 commercial breeder-finisher units in the West-Midlands region of England. Faecal samples were examined for parasite eggs (Ascaris suis, Trichuris suum and strongylid species) using faecal flotation; and for Lawsonia intracellularis bacteria using the polymerase chain reaction. Feed samples were subjected to proximate analysis for energy, protein and fibre content and enzymic colorimetry for levels of non-starch polysaccharides (NSPs). Characteristics relating to housing, feeding and dung disposal systems and husbandry practices were recorded for each farm and assessed for their association with the presence of parasites and L. intracellularis at the herd level. Ascaris eggs were identified in 8% of herds, Trichuris eggs in 20% of herds and in strongylid eggs (Oesophogostomum and/or Hyostrongylus) in 44% of herds. Lawsonia intracellularis was detected in 15% of herds investigated. Herds positive for Trichuris and Ascaris had significantly lower levels of digestible energy and higher levels of neutral detergent fibre, total and insoluble NSPs in their diets than negative herds (p < 0.05). Housing weaners on slatted floors was associated with a significant decreased risk of parasite infection in grower-finishers (odds ratio = 0.09, p = 0.04) compared to housing on solid floors. The use of grower diets high in NSPs was associated with an increased risk of Trichuris infection (odds ratio = 27.6, p = 0.007). There was also an association at the herd level between infection with L. intracellularis and the presence of Trichuris eggs (odds ratio = 17.43, p = 0.069). It is concluded that control of dietary fibre intake (NSPs in particular) for growers and environmental hygiene (dung removal) for weaners appear to be the most important factors controlling parasite infection in grower-finisher pigs in the UK at present. The current move towards more straw based systems is thus likely to exacerbate the influence of these factors and is likely to result in increased parasite infection in grower-finisher pigs in the UK.

Population genetic models of genomic imprinting.

The phenomenon of genomic imprinting has recently excited much interest among experimental biologists. The population genetic consequences of imprinting, however, have remained largely unexplored. Several population genetic models are presented and the following conclusions drawn: (i) systems with genomic imprinting need not behave similarly to otherwise identical systems without imprinting; (ii) nevertheless, many of the models investigated can be shown to be formally equivalent to models without imprinting; (iii) consequently, imprinting often cannot be discovered by following allele frequency changes or examining equilibrium values; (iv) the formal equivalences fail to preserve some well known properties. For example, for populations incorporating genomic imprinting, parameter values exist that cause these populations to behave like populations without imprinting, but with heterozygote advantage, even though no such advantage is present in these imprinting populations. We call this last phenomenon "pseudoheterosis." The imprinting systems that fail to be formally equivalent to nonimprinting systems are those in which males and females are not equivalent, i.e., two-sex viability systems and sex-chromosome inactivation.

Contact with oestrous female pigs stimulates and synchronises puberty in gilts.

Three experiments, using a total of 132 pre-pubertal gilts, were carried out to investigate the influence of contact with oestrous female pigs on the attainment of puberty by gilts. Experiment 1 compared the effect of removing the gilts from their groups as they reached puberty in response to exposure to a boar, with leaving the gilts in their groups for five to 15 days after puberty or five to 15 days after second oestrus. All the groups exposed to boars reached puberty significantly earlier than controls (P less than 0.05) but there was no difference between these groups in their mean age at puberty. However, the synchrony of puberty was significantly greater among the gilts which remained in their groups after puberty (P less than 0.01) or second oestrus (P less than 0.001) than among the gilts which were removed at puberty. Experiment 2 investigated the influence of housing pre-pubertal gilts with penmates induced into puberty with injections of oestradiol benzoate. Puberty was significantly advanced by the presence of penmates regularly exhibiting oestrous periods. Experiment 3 compared the effect of daily exposure to an anoestrous ovariectomised sow, an oestrous ovariectomised sow or a boar, on the attainment of puberty by gilts. Gilts exposed to either an oestrous sow or a boar were significantly younger at puberty than isolated control animals (P less than 0.05) whereas the mean age at puberty of gilts exposed to an anoestrous sow was not significantly different from that of controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Contact with a sow in oestrus or a mature boar stimulates the onset of oestrus in weaned sows.

Post weaning anoestrus can represent a significant source of reproductive inefficiency in pig production. Although many factors such as breed, parity, season and nutrition are known to influence the interval between weaning and remating, the effect of the sow's social environment after weaning is largely unknown. For this experiment six groups of Large White/Landrace cross-bred sows weaned between August 1989 and March 1990 at a mean of 29 days after farrowing were used to investigate the effect of social environment on the onset of oestrus after weaning in the sow. Groups two, three or four sows were exposed in six replicates to the following four treatments: (1) 18 were isolated as controls, (2) 16 were housed next to an anoestrous ovariectomised sow and allowed 10 minutes physical contact with it daily, (3) 15 were housed next to an ovariectomised sow, induced into oestrus by the injection of 1 mg oestradiol benzoate, and allowed 10 minutes physical contact with it daily, and (4) 16 were housed next to a mature boar and allowed 10 minutes physical contact with it daily. Significantly more sows in treatments 3 and 4 showed oestrus within 10 days of weaning (P less than 0.05), and the onset of oestrus was more synchronised in the sows in treatment 3 than in any other treatment (P less than 0.001). The exposure of the weaned sows to an oestrous sow or a boar overcame the extension of the weaning to remating interval which occurred over the summer and in primiparous animals in other treatments.

Concentrations of plasma melatonin and luteinizing hormone in domestic gilts reared under artificial long or short days.

Plasma melatonin concentrations were measured every 1-2 h over 24 h and plasma luteinizing hormone (LH) concentrations every 15 min over 12 h in domestic gilts reared under artificial light regimens that had previously been used to demonstrate photoperiodic effects on puberty. In Expt 1, the light regimens both commenced at 12 h light: 12 h dark (12L:12D) and either increased (long-day) or decreased (short-day) by 15 min/week until the long-day gilts were receiving 16L:8D and the short-day gilts 8L:16D at sampling. In Expt 2, both light regimens commenced at 12L:12D and either increased (long-day) or decreased (short-day) by 10 or 15 min/week to a maximum of 14.5L:9.5D or a minimum of 9.5L:14.5D before being reversed. Sampling took place when daylength had returned to 14L:10D (long-day) or 10L:14D (short-day). In immature gilts housed at 12L:12D (Expt 1) and in postpubertal (Expt 1) and prepubertal (Expt 2) gilts reared under long-day or short-day light regimens, mean plasma melatonin concentrations were basal (3.6 pg/ml) when the lights were on and increased to peak concentrations greater than 15 pg/ml within 1-2 h after dark, before declining gradually to basal concentrations at or near the end of the dark phase. In prepubertal gilts bearing subcutaneous melatonin implants and reared under long-days (Expt 2), mean plasma melatonin concentration in the 6 h before dark was 91.9 +/- 5.26 pg/ml and 125.0 +/- 6.66 pg/ml 1 h after dark, but this increase was not statistically significant. In Expt 2, the short-day gilts had fewer LH pulses (2.6 +/- 0.25 vs. 4.6 +/- 0.24; P less than 0.01) in the 12-h sampling period than the long-day gilts, but the amplitude of the pulses (2.28 +/- 0.23 vs. 1.26 +/- 0.16 ng/ml; P less than 0.01) and the area under the LH curve (78.8 +/- 5.60 vs. 47.3 +/- 6.16; P less than 0.01) was greater in the short-day gilts. In the short-day, but not in the long-day, gilts LH pulses were more frequent (2.0 +/- 0.0 vs. 0.6 +/- 0.25; P less than 0.01), but had a smaller area (61.9 +/- 7.2 vs. 120.2 +/- 23.6; P less than 0.05) in the 6 h of dark than in the 6 h of light, which together made up the 12-h sampling period.(ABSTRACT TRUNCATED AT 400 WORDS)

Importance of non-olfactory ram stimuli in mediating ram-induced ovulation in the ewe.

In Exp. 1, 4 groups of 50 recently weaned ewes were exposed to various degrees of contact with rams for 65 days, followed by exposure to novel rams for 4 days. Ovarian activity in the ewes was determined by laparoscopy on Days 29, 65 and 69 of treatment. There were no treatment differences in the percentage of ewes ovulating on Day 4 whereas by Day 29 more ewes in clear fenceline and full ram contact were ovulating compared to controls (P less than 0.05, P less than 0.001). After 65 days ovarian activity was significant only in those ewes in full contact with rams (P less than 0.001). Between 89 and 95% of ewes remaining anovulatory after 65 days ovulated after 4 days of full contact with novel rams. In Exp. 2, 4 groups of about 30 anovulatory ewes were exposed to various degrees of contact with rams for 5 days. Ovarian activity was assessed before and after treatment by laparoscopy. After 5 days, more ewes were ovulating in response to full ram contact than in any other treatment (P less than 0.05) and more ewes in fenceline contact with rams or with rams plus ewes were ovulating than in the isolated control treatment (P less than 0.01). In Exp. 3, 6 groups of about 40 anovulatory ewes were exposed to face masks with and without rams' wool and/or various degrees of contact with rams for 5 days. More ewes were ovulating after 5 days in the group in full physical contact with rams than in any other group (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of short-term elevations in plasma cortisol concentration on LH secretion in prepubertal gilts.

Prepubertal gilts were fitted with jugular vein and carotid artery catheters at 148 days of age. At 160 days of age the 24 gilts were allocated to treatment in a 2 x 2 factorial design involving intra-carotid infusion of cortisol (10 mg in 40 ml saline) or saline alone with or without i.v. injection of 5 micrograms synthetic GnRH midway through the 1 h infusion. Plasma cortisol concentrations were elevated in gilts infused with cortisol (P less than 0.05). The LH response to exogenous GnRH was reduced by cortisol infusion. Treated gilts released less LH (P less than 0.001) and had a lower mean LH peak (P less than 0.01) than did control gilts but the timing of the induced LH peak was not affected. In the absence of an exogenous GnRH challenge, cortisol infusion increased the endogenous secretion of LH (P less than 0.01). These results suggest that acute elevations in plasma cortisol concentration may be involved in mediating changes in pituitary responsiveness and the secretion of LH in the peripubertal gilt.

The influence of male contact on plasma cortisol concentrations in the prepubertal gilt.

Large White X (Large White X Landrace) prepubertal gilts, 165 days of age, were fitted with indwelling venous catheters and housed in modified metabolism crates. After a period of acclimatization, frequent blood samples were taken at regular intervals before, during and after the 7 gilts were exposed to various degrees of contact with male pigs. The plasma samples were assayed for cortisol concentration using a competitive protein-binding radioassay. Significantly elevated concentrations of plasma cortisol (P less than 0.001) occurred only when full physical contact between the boar and the gilts was allowed. Boar exposure without full physical contact induced only minor changes in plasma cortisol concentrations of gilts. Plasma cortisol concentrations have been shown to constitute a reliable indicator of a stress response in pigs, and so the results of this study suggest that tactile stimulation from a male pig induces a stress response in the recipient prepubertal gilt. This stress response in the gilt may be involved in the stimulation of puberty onset by contact with a mature boar (i.e. the 'boar effect').