Postweaning mortality in Manitoba swine

A case-control study to investigate the contribution of postweaning multisystemic wasting syndrome (PMWS) and Porcine circovirus type 2 (PCV-2) to deaths among piglets of nursery age (19 to 68 d) in Manitoba indicated a significant positive association between PCV-2 infection and an increased mortality rate in nursery pigs. The clinical syndrome PMWS was seldom recognized in case or control herds; however, PCV-2 infection was widespread at the herd level. Other factors more strongly associated with increased piglet mortality rate than herd level PCV-2 infection were Mycoplasma hyopneumonia infection, porcine reproductive and respiratory syndrome (PRRS), and diarrhea caused by Eschericia coli K88. Management factors associated with case herd status included close proximity to other herds, larger number of sows supplying pigs to the nursery, larger range in age and weight going into the nursery, the moving of lightweight pigs into another nursery room at the end of the nursery fill, and not using spray-dried plasma in the 1st nursery ration. These results highlight the host-agent-environment triad leading to high nursery-barn mortality rates.     

Status of Trichinella spiralis in domestic swine and wild boar in Canada.

Evidence of the status of trichinellosis in Canada's national swine herd is provided from data acquired through national surveillance programs and from a prevalence study of Trichinella in wild boar and domestic swine. More than 500,000 swine tested at abattoirs in ongoing animal health surveys since 1980 and 2 national swine serological surveys (1985 and 1990) showed no evidence of Trichinella infection, except for 3 occurrences in a small infected zone in Nova Scotia. The prevalence study of domestic swine and wild boar was conducted for the prevalence of Trichinella after an epidemiological investigation of a 1993 outbreak of human trichinellosis in Ontario showed that the disease was linked to the consumption of wild boar meat originating from 2 farms in the province. Sera and tissues were collected from 391 wild boar and 216 domestic swine originating from 228 farms in Quebec, Ontario, Manitoba and Saskatchewan. The survey examined approximately 37% of the wild boar slaughtered in Canada in 1994. A pepsin-HCl digestion test of the tissues and an ELISA performed on the sera did not yield any positive results. These findings and the lack of human cases of Trichinella from the consumption of Canadian pork for nearly 2 decades suggest that the parasite has been rare in domestic swine and wild boar raised in Canada. Trichinella spiralis has only been found sporadically in swine in a small region within Nova Scotia.     

Lighting and mortality rates in domestic fowl

1. Data from intermittent and conventional lighting trials were analysed to investigate the effect of daily illumination upon mortality during the laying period and in 49‐d‐old broilers.

2. Iiveability in laying hens was improved by the use of intermittent lighting: the degree of improvement was proportional to the reduction in daily illumination achieved by the intermittent programme.

3. The reduction in mortality with intermittent lighting in laying hens was not the result of intermittent lighting per se. Intermittent regimens which did not reduce daily illumination did not reduce mortality.

4. Mortality in both conventionally‐lit laying hens and 49‐d old‐broiler chickens increased with photoperiod.     

Chlamydial infection and perinatal mortality in a swine herd

Chlamydia psittaci was believed responsible for an episode of high perinatal death loss in a swine herd in which 8.5 pigs per litter normally were weaned. In this episode, 18 sows produced 186 pigs, with 50 survivors. Chlamydia was found in tissue samples, and other bacterial or viral pathogens could not be identified. Chlamydia was diagnosed by isolation (ELISA), histologic examination using immunoperoxidase staining techniques, and electron microscopy. Previously, C psittaci has not been considered in the differential diagnosis of swine perinatal mortality.     

High mortality of domestic turkeys associated with Ascaridia dissimilis.

Third- and fourth-stage Ascaridia dissimilis larvae were isolated from commercial white turkey intestinal scrapings from two farms that were experiencing high mortality. Lesions consisted of a necrotic-like enteritis that was most severe in the jejunum. Subsequent bacteriological isolation yielded heavy growth of Escherichia coli and Clostridium perfringens. The rate of mortality declined rapidly when the turkeys were administered 18 ppm fenbendazole for 7 days.     

Daytime shelter-seeking behavior in domestic horses

We examined daytime shelter-seeking behavior (SSB) in domestic horses housed outdoors and studied the relationship of temperature, precipitation, and wind speed with SSB. We studied 50-60 Arabian horses (depending upon time of year) and 3-5 draft horses. Horses were divided among 8 pastures containing sheds. There were 2 study phases. In the first, up to 676 scan samples were taken for each pasture over a 12-month period (total observations = 5,025). At each observation, we noted whether or not a shed was being used. In the second phase, randomly selected focal animals were chosen from each pasture and observed twice per week for 16 weeks. Forty-four focal animals were observed (total observations = 3930). At each sampling time, we noted weather conditions and recorded whether each subject was standing or lying inside or next to shelters. Shelter usage ranged from a low of <10% of observations in many weather conditions to a high of 62% of observations when it was snowing and wind speed was >4.9 m/s. When wind was >2.2 m/s, there was a significant effect of rain on shelter usage, that is, more horses used shelters in rainy, breezy conditions (P < 0.01). When wind was >2.2 m/s, there was a significant effect of snow on shelter usage, that is, more horses used shelters in snowy, breezy conditions (P < 0.01). Though overall shelter usage was typically <10%, it appears that shelter access is very important in certain weather conditions.     

Patterns of crossfostering and piglet mortality on commercial U.S. and Canadian swine farms

A data base of 300 farms using computerized records was used to examine the extent and timing of crossfostering being practiced in commercial herds in the Midwestern U.S. and Canada in 1994–1995. Crossfostering was used on 98% of farms. Across all farms, the mean percent of piglets crossfostered was 8.6%. Farms varied greatly in the age at which they moved piglets. The 20 farms that moved piglets the earliest after birth were classified as early-move farms and the 20 that moved the oldest piglets were classified as late-move farms. Early-move and late-move farms did not differ in herd size (P = 0.14), average parity of farrowed sows (P = 0.47) or age at weaning (P = 0.37). There were differences between early-move and late-move farms in percent of piglets fostered (P = 0.0001), pigs born alive/litter (P = 0.04), and pre-weaning mortality (P = 0.0005). A subset of late-move farms that were part of an integrated production group had unique production parameters that suggested inaccurate record-keeping.     

Neonatal survival in swine: effects of low birth weight and clinical disease

Data were collected for 3,636 full-term pigs born in a commercial swine herd to determine the effects of birth weight and clinical disease on survival during the first 3 weeks of life. Logistic regression models were constructed for 7-day survival for all live-born pigs, and for 21-day survival for pigs surviving the first week of life. Estimates of birth weight and disease effects were adjusted simultaneously for other risk factors including litter size, parity, and within-litter variation in birth weight. The 7-day survival model indicated that survival odds improved significantly with increasing birth weight. Maximal survival, relative to pigs weighing less than 601 g at birth, was evident in pigs weighing greater than 2 kg at birth (odds ratio [OR] = 349). Diarrhea (OR = 2.7) and splayed limbs (splay leg; OR = 37.3) significantly (P less than 0.05) reduced 7-day survival. Models of 21-day survival indicated a smaller, but still significant, effect of birth weight on survival. Adjusted survival odds for pigs in the heaviest weight group (greater than 2 kg) were 20.1 times higher than pigs weighing less than 801 g. Diarrhea (OR = 2.7) and lameness (OR = 2.6, 2 limbs) significantly (P less than 0.05) decreased 21-day survival.     

Sire and breed effects on mortality in the offspring of swine

Sire effect on the mortality of their offspring was studied on 2 farms. On Farm 1, preweaning mortality was recorded during a 6-month period in 200 litters sired by 6 boars. Pre-weaning mortality rates in the offspring of the 6 boars were 12.2, 16.0, 17.5, 22.0, 25.4 and 28.2%. These mortality rates were significantly different (P < 0.05).On Farm 2, nursery and finishing house-deaths in the offspring of 13 boars of 3 breeds were recorded over a 1-year period. According to the breed of the sire, pigs had significantly different (P < 0.05) mortality rates of 1.8, 3.1 and 3.5%.     

Effect of fusaric acid on brain regional neurochemistry and vomiting behavior in swine.

Fusaric (5-butylpicolinic) acid is a phytotoxin produced especially by Fusarium moniliforme, a mold commonly found in Canadian-grown corn. Experiments were conducted to determine the effects of acute doses of fusaric acid on brain neurochemistry and behavior in swine. A total of 40 crossbred barrows (initial weight 10 kg) were orally dosed with 0 or 200 mg of fusaric acid/kg of BW and five animals from each treatment were killed 4.5, 9, 18, or 36 h after dosing. All brains were dissected, and concentrations of indoleamine and catecholamine neurotransmitters and metabolites were determined. Animals in the group killed 36 h after dosing were observed for behavioral changes. Vomiting was noted in 60% of the pigs dosed with fusaric acid. These pigs also seemed more lethargic than controls and appeared sedated. The major neurochemical changes due to exposure to fusaric acid were seen in the hypothalamus 18 h after dosing. Brain tryptophan, serotonin, and 5-hydroxyindoleacetic acid all tended to be elevated by the action of fusaric acid. Brain catecholamine concentrations were largely refractory to treatment. It was concluded that exposure to acute doses of fusaric acid can cause vomiting and neurochemical changes in swine. Fusaric acid may, therefore, be acting synergistically with trichothecene mycotoxins to cause vomiting and feed refusal in pigs consuming trichothecene-contaminated feedstuffs.     

Experimental studies on the course and the effects of pediculosis in domestic swine

Weaned piglets, aged between six and eight weeks, underwent one single experimental infection, using few imaginal stages as well as second and third larval stages of Haematopinus suis. Louse populations of various densities developed on animals of the same litter under the same keeping and feeding conditions. No unambiguous reduction in body weight increase was observed throughout the two months of the experiment. Even pigs with 2,107 or 2,135 adult lice and their larval stages were not affected. Some of the pigs developed allergic dermal inflammations in the course of pediculosis and suffered from considerable aggravation of pruritus which used to be of minor importance before. Excessive rubbing, in response to that itching, led to mechanically caused skin lesions, some of them bleeding.     

Genotyping of Clostridium perfringens isolated from domestic and exotic ruminants and swine

Clostridium perfringens types A, B, C, D and E are known to cause severe enteritis/enterotoxaemia and diseases (especially caused by type A) belonging to the gas oedema complex in many species. Samples from the small intestine as well as faeces of domestic and exotic animals suffering from enterotoxaemic signs or having died within days after first occurance of toxaemia were submitted for typing C. perfringens toxovars by multiplex PCR. The following species have been investigated: domestic sheep (Ovis ammon; n = 10), domestic goat (Capra aegagrus hircus; n = 26), Japanese serow (Capricornis sumatraensis; n = 4), lechwe waterbuck (Hydrotragus leche; n = 1), blackbuck (Antilope cervicapra; n = 1), European reindeer (Rangifer tarandus tarandus; n = 4), domestic swine (Sus scrofa; n = 52), and collared peccary (Tayassu albirostris; n = 1). Interestingly, the predominant C. perfringens toxovar in domestic sheep was type A. This toxovar could also be diagnosed in all reindeer, in three Japanese serows, one lechwe waterbuck and most pigs (n = 47), the majority of those being at suckling age. Type D was the most prevalent toxovar (n = 18) in domestic goats, but also types A and E could be identified as pathogens in this species. Type C could only be found in domestic swine (n = 5) and in one case of clostridiosis in a Japanese serow. Two cases of enterotoxaemia in goats, one case in reindeer, and a single case in blackbuck and collared peccary were caused by C. perfringens type E. Genotyping of C. perfringens is recommended before starting vaccination programmes as it could be shown, that the importance of specific toxovars has been underestimated in specific species and/or age groups.     

Genetic analysis of behavior traits in swine production

Estimates of genetic parameters related to pig behavior under stressful situations are required before selection programs can be designed to produce more docile pigs. Pig behavior was evaluated in a pedigreed Landrace–Duroc–Yorkshire composite population. Piglets were evaluated for their response to handling at 1 d of age (n=11069), being placed on their back for 60 s at ~24 d of age (n=975), and being confined in a scale while backfat measurements were being collected (n=9035). Feeding behavior was monitored in a growing–finishing facility (n=1162) including preferences for feeding positions. Feeders were placed along a fence with one end adjacent to a gate (gate-end) and the other end open. An animal model was fitted to the data using WOMBAT where litter was included for d 1 activity scores and backtest traits. Fixed effects of sex, pen/year-season/date of collection in all analyses along with scorer (d 1 activity score) and a covariate of age (d 154 weight and backfat). Multiple trait models were fit to estimate genetic covariances among traits. All estimates of heritability were significantly different than zero. Activity scores and backtest traits had the lowest estimates of heritability (0.15–0.19), measures of feeding behavior were more variable (0.16–0.60) while production data had high heritabilities (>0.5). Genomic heritability estimates were similar to standard heritability estimates for most traits, except traits measured at a young age. All traits measured during the backtest had strong genetic correlations and similar estimated heritability. Among feeding behavior traits, number of meals/d and average meal length were highly correlated with total daily meal time. In addition, animals that preferred to eat alone avoided the open-end position at the feeder. The only behavioral traits with genetic correlations significantly different from zero with production traits were associated with feeding behavior where animals that ate longer meals and spent more time at the feeder/d tended to be heavier and fatter at 154 d. In addition, animals that ate more meals/d were fatter and animals that preferred the gate-end position of the feeder were heavier. Pigs with more reactive personalities tended to eat fewer meals/d, each longer in duration, and they preferred the gate-end feeder position. The measures of pig behavior studied were heritable and selection for more docile pigs should not have large detrimental effects on performance.