Prevalence of ketonemia and associations with herd size, lactation stage, parity, and postparturient diseases in Jordanian dairy cattle.

The prevalence of bovine ketonemia among 1155 dairy cows in various stages of lactation and parity on 25 Jordanian dairy herds was studied. The cross-sectional study was conducted during the spring of 1992. Serum concentration of beta-hydroxybutyrate (BHB) <0.9 mmol/l, between 0.9 and 1.7 mmol/l, and >1.7 mmol/l were considered to indicate normal, mild and severe ketonemia, respectively. The point prevalences of mild and severe ketonemia were 22% and 3.8%, respectively. The prevalence of ketonemia decreased with increasing herd size. Associations between the prevalence of ketonemia and parity, stage of lactation, metritis, somatic-cell count (SCC) and serum cholesterol levels were not significant (p > 0.05).     

改进集约化养猪生产环境的措施

为建立和改善养猪生产环境，提高集约化养猪生产水平。综合分析了集约化猪场生产环境中存在的主要问题，介绍了改善和治理养猪生产环境的措施和方法。     

A longitudinal study of rotavirus antibody titers in swine in a closed specific pathogen-free herd.

In a newly established closed specific pathogen-free (SPF) swine herd, gilt/sow suckling and weaned pig rotavirus specific antibody titers were followed for three lactations by enzyme-linked immunosorbent assay (ELISA) to gain insight into the dynamics of herd antibody titers to group A rotavirus. Among gilts/sows, serum antirotavirus IgG titers increased during each lactation with a subsequent drop in titer between farrowings. Serum antirotavirus IgM titers declined during each lactation and with subsequent parity. Serum antirotavirus IgA titers remained constant during lactations and among parities. In colostrum and milk, antirotavirus IgA antibody was abundant. Differences in titer were not noticed between gilts and second litter sows but third litter sows had significantly higher titers than the first two groups. Antirotavirus IgG was high in colostrum but nearly nonexistent in milk. This titer did not vary significantly within or among parities. There was a linear regression in the titers of baby pig serum antirotavirus IgG from the post colostral sample through to seven weeks old, after which titer began to increase. No difference in baby pig serum antirotavirus IgG was noted among the three litters. Serum antirotavirus IgA and IgM were undetectable in baby pig sera after 2-3 weeks of age. Coproantibody to rotavirus was sporadically present in pig feces for 2-3 weeks after birth with highest titers in the IgA fraction. We conclude that although it is probable that age resistance of pigs to rotavirus diarrhea occurs, humoral immunity as measured by ELISA rotavirus antibody titers may not be intimately involved in virus clearance since in our studies baby pigs passively received large amounts of antibody but still excreted pathogenic virus. The finding of increasing levels of serum antirotavirus IgG in gilt/sow serum suggest that exposure to antigen of dams occur without significant increases in antirotavirus IgG titers in either colostrum, milk, or baby pig serum.     

Economic assessment of a pseudorabies epizootic, breeding herd removal/repopulation, and downtime in a commercial swine herd

The effect of pseudorabies in a 150-sow farrow-to-finish operation on selected production and economic values was estimated. Mean litter size remained the same throughout the observation period; however, there was a 2-fold increase in suckling pig mortality and a 3.5-fold increase in stillbirths when the months of the epizootic were compared with pre-epizootic months. Following the epizootic, suckling pig mortality was 13.7% greater (P less than 0.05) than that observed in the months preceding the epizootic, whereas stillbirth rate was 71% higher (P less than 0.01) than that reported in the pre-epizootic months. Total net loss for this operation was estimated at +48,175. The major economic losses (approximately 88% of the total loss) were related to breeding herd removal/repopulation and production downtime.     

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.     

The shedding of group A rotavirus antigen in a newly established closed specific pathogen-free swine herd.

A longitudinal study was undertaken in a newly established specific pathogen-free (SPF) swine herd to determine the dynamics of rotavirus antigen shedding in a closed swine facility. Pregnant SPF gilts which populated the herd, and their offspring, were monitored weekly for three consecutive lactations. Fecal samples were assayed for the presence of group-specific viral antigen by a solid phase immunoassay (ELISA). Results indicate that in the week prior to farrow, 35% of samples from gilts/sows contained rotavirus antigen. During nursing, 37% of the gilts'/sows' fecal samples also contained virus antigen. Over the course of three farrowings, every gilt/sow in the herd excreted virus antigen. Virus antigen was present in 25% of the samples tested from nursing pigs and in 70% of the samples tested from pigs in the postnursing period; 95% of the litters excreted virus antigen either while nursing or postweaning. Seasonal incidence in virus antigen excretion was noted with proportionally more suckling pigs virus antigen-positive in summer and proportionally more sows/gilts positive during winter. Diarrhea occurred only rarely in the sampled population. Although piglets shed rotavirus subclinically, ELISA positive feces from piglets of each lactation caused severe disease when fed to neonatal gnotobiotic pigs. Electropherotyping of these passaged viruses indicated minor variation in RNA banding patterns over time.     

Genetic relationships between length of productive life and lifetime production efficiency in a commercial swine herd in Northern Thailand

Genetic parameters and trends for length of productive life (LPL), lifetime number of piglets born alive per year (LBAY), lifetime number of piglets weaned per year (LPWY), lifetime litter birth weight per year (LBWY) and lifetime litter weaning weight per year (LWWY) were estimated using phenotypic records of 3085 sows collected from 1989 to 2013 in a commercial swine farm in Northern Thailand. The five‐trait animal model included the fixed effects of first farrowing year‐season, breed group and age at first farrowing. Random effects were animal and residual. Heritability estimates ranged from 0.04 ± 0.02 for LBWY to 0.17 ± 0.04 for LPL. Genetic correlations ranged from 0.66 ± 0.14 between LPL and LBAY to 0.95 ± 0.02 between LPWY and LWWY. Spearman rank correlations among estimated breeding values for LPL and lifetime production efficiency traits tended to be higher for boars than for sows. Sire genetic trends were negative and significant for all traits, except for LPWY. Dam genetic trends were positive and significant for all traits. Sow genetic trends were mostly positive and significant only for LPWY and LBWY. Improvement of LPL and lifetime production efficiency traits will require these traits to be included in the selection indexes used to choose replacement boars and gilts in this population.     

Partitioning of herd,year and season variation in milk production

Variances in milk and fat yields due to herd-period-season effects (period either 6 or 12 months, and season either 1, 2 or 4 months) were partitioned fitting a three nested effects model with herd, period within herd and season within period within herd as random nested effects, sire a fixed effect and linear and quadratic regressions on age at calving. The overall effects of period and season of calving were regarded as fixed effects and were removed by precorrecting records using least squares constants estimated from the same data. Environmental correlations within herd, herd-period and herd-period-season were also estimated for all period and season groupings. Records of first lactation milk and fat yields on 25 158 progeny of 69 widely used proven Friesian-Holstein sires in 832 herds in England and Wales were used.The variance components for the effects of herd, period within herd, season within period within herd and residual accounted for 31, 6, 5 and 58% of the total variance in milk yield, and 35, 8, 7 and 50% of the variance in fat yield, respectively, using a period of 12 months and a season of 4 months. Differences amongst correlations within the same herd-period-season, fitting seasons of different lengths, were small. It was therefore concluded that shorter seasons in a herd-period-season fixed effect model of sire evaluation would be of no advantage.     

Epidemiology of Pasteurella multocida in a farrow-to-finish swine herd.

Thirty-eight clinical isolates of Pasteurella multocida, recovered from a continuous flow, farrow-to-finish swine herd, were characterized by capsular serotyping and restriction endonuclease analysis (REA) in order to study the epidemiology of P. multocida pneumonia. Twenty-three of the 38 isolates obtained in the study belonged to serotype A. They displayed three REA patterns after digestion with HpaII, of which one designated A-3 represented 70% of the samples. The remaining 15 isolates were serotype D. Four different REA patterns were observed in the type D isolates. The REA type D-1 was most prevalent and accounted for 47% of the serotype D isolates. All serotype A isolates were nontoxigenic, whereas five (33%) of the serotype D isolates were toxigenic. Vertical transmission of P. multocida could not be demonstrated, and was probably not a major route of infection. The results of this study suggest that strains of P. multocida virulent for pigs exist and cause swine pneumonic pasteurellosis in continuous flow herds by horizontal transmission.     

Financial evaluation and decision making in the swine breeding herd.

As the swine industry continues to evolve and develop a greater business orientation--one that demands justification of costs, benefits, and risk-exposure--the veterinarian will be confronted with the need to develop an economic basis to supplement the biologic. The profession should view such a challenge as an opportunity to broaden its role in serving the businesses that make up the industry. However, to be effective in such an expanded role requires that the veterinarian develop a good working knowledge of risk and risk management as well as the role played by economic evaluation techniques used in financial evaluation in the risk management process. Several potential advantages exist for the veterinarian who determines to expand his or her risk management role by using financial evaluation in the course of day-to-day practice routine: Additional service or consulting income may be generated through evaluating alternatives through decision analysis. Client confidence may be strengthened in the veterinarian and in the recommendations made. The costs of consulting services and health products for the client may be viewed as income-generators instead of being viewed solely as expenses. Referrals of additional progressive clients may be generated by satisfied current clients. The veterinarian may achieve personal satisfaction through substantiating his or her recommendation beyond clinical or experimental judgment. With the capability of using financial evaluation techniques in the evaluation and justification of recommendations comes significant responsibility. Reliance upon financial evaluation techniques as a more objective approach in the management of risk for clients carries with it an inherently greater degree of trust. Such trust must be deserved. The universal adage "garbage in, garbage out" applies directly to financial evaluation. Financial evaluation techniques have the potential to provide the decision-maker with objective and accurate analysis, improving the probability of choosing an optimal course of action for the business. However, the objectivity and accuracy achievable is highly dependent upon the quality and quantity of information used in the analysis. Veterinarians must be cognizant of the increased responsibility demand placed on those using financial evaluation techniques to direct the course of action for their clients. Financial evaluation tools are available to decision-makers that may improve the objectivity of the decision-making process, providing for a greater degree of confidence in the expected outcome. Stated another way, these tools can reduce the number of surprises a decision-maker encounters as a result of the decisions made.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pathogen group specific risk factors at herd, heifer and quarter levels for intramammary infections in early lactating dairy heifers

Risk factors for intramammary infections caused by coagulase-negative staphylococci, contagious major pathogens and environmental major pathogens in early lactating heifers were evaluated at the herd, heifer and quarter levels. In total, 764 quarters of 191 dairy heifers in 20 randomly selected farms in Flanders (Belgium) were sampled. Quarter milk samples were collected between 1 and 4 days in milk and between 5 and 8 days in milk for bacteriological culture. Data were analyzed using multivariable, multilevel logistic regression analysis. Higher average herd milk somatic cell count (>200,000 cells/mL), not having an effective fly control strategy, contact with lactating cows prior to calving and moderate to severe udder edema prior to calving increased the odds of intramammary infections caused by contagious major pathogens. Poor heifer hygiene and lack of mineral/vitamin supplementation prior to calving were risk factors for intramammary infection caused by environmental major pathogens. Teat apex colonization with coagulase-negative staphylococci prior to calving seemed to protect quarters against intramammary infections caused by major pathogens. Poor heifer hygiene before calving, a non-clipped udder and not practicing of teat dipping prior to calving increased the odds of intramammary infection with coagulase-negative staphylococci. Although management is important in the prevention and control of intramammary infections in early lactating heifers, most variation in the prevalence of intramammary infections resided at the heifer and quarter levels, indicating that the susceptibility for intramammary infections around calving is mainly determined by heifer and quarter characteristics.     

Environmental source of mycobacteriosis in a California swine herd.

Between July 1985 and April 1986, mycobacterial lymphadenitis was recorded in six of 2407 slaughter pigs from a commercial swine herd in which the majority of pigs were raised in confinement. Records showed that all six affected pigs had access to dirt-floored pens at least 81 days prior to slaughter. The mycobacteriosis lesion rate for pigs exposed to dirt pens was 9.4% while in nonexposed pigs the lesion rate was zero. The risk associated with movement of pigs from concrete floored pens to dirt pens was evaluated by a field trial. In the field trial, two litters (5 of 15 pigs) exposed to dirt pens at 12-24 days of age but none of nine nonexposed litters (39 pigs) developed lesions. Mycobacterium avium-complex bacteria were recovered from both exposed litters (9 of 15 pigs) but from none of nine nonexposed litters. Serovars of M. avium-complex isolated from trial pigs included 1, 4, 8, 9, the dual serovar 4/8, and an untypable serovar. Incense-cedar bark (Calocedrus decurrens) used as a flooring material in the pens was demonstrated to be a potential source of M. avium-complex serovar 9. The dual serovar 4/8 and an untypable M. avium-complex were isolated from the dirt-floored pens. No evidence of cross-transmission of M. avium-complex infection was detected. The sporadic pattern of mycobacteriosis observed in the herd probably resulted from infrequent exposure to a common environmental source.     

Computer simulation model of swine production systems: III. A dynamic herd simulation model including reproduction

A dynamic herd simulation model for a swine production unit has been developed. The model is discrete and stochastic and the appropriate random distributions have been defined from the literature or empirically estimated. Theoretical concepts and relationships presented previously are used to simulate growth and the overall life cycle of individual animals. Simulated animals are young pigs (from birth to slaughter age), gilts, and sows. Animal events are farrowing, weaning, mating, end-nursery (transfer from nursery to the growing-finishing facility), and slaughter and are processed individually using a next-event scheduling orientation package. Animals within the herd are culled for different health and reproductive reasons. Genetic parameters, diet composition, and herd management are input variables chosen by the user. The effects of nutrition, genetics, season, and other factors on several reproductive parameters are considered. Model evaluation is performed by studying the output of the model under specified herd situations. The herd model adequately simulates animal flow and dynamics of the herd.     

Prevalence of and risk factors for influenza in southern Ontario swine herds in 2001 and 2003

This research included 2 prevalence studies and a risk-factor investigation conducted in 2001 at 93 sites with sows only, finishers only, or both. In 2001, 1300 serum samples from sows in 65 herds and 720 serum samples from finisher pigs in 72 herds were tested for antibodies to swine influenzavirus (SIV) of H1N1 subtype with an enzyme-linked immunosorbent assay (ELISA). In 2003, 1140 serum samples from sows in 76 herds were tested for antibodies to SIV of H3N2 subtype with a hemagglutination-inhibition assay based on A/Swine/Colorado/1/77 and A/Swine/Texas/4199-2/98 isolates. The apparent pig-level H1N1 seroprevalence in 2001 was 61.1% and 24.3% in sows and finishers, respectively. The apparent pig-level seroprevalence in 2003 for H3N2 A/Sw/CO/1/77 and A/Sw/TX/4199-2/98 in sows was 0.6% and 0.7%, respectively. The factors associated with sow-herd H1N1 positivity included pig or farm density at different geographic levels, an external source of breeding pigs, number of animals on site, and decreasing proximity to other barns. Higher-parity sows had higher odds of seropositivity, but there was significant random variability in this association among herds. The odds of finisher-herd SIV positivity were higher with large herd size, high pig farm density, and farrow-to-finish type of farm. Finisher herds were SIV-positive only if source sow herds were positive. Simultaneously, 45% of finisher herds were SIV-negative although sow source herds were positive.     

Reproductive consequences of an X-autosome translocation in a swine herd.

A survey was conducted on the chromosome makeup and breeding data of pigs housed at the Arkell Research Station, University of Guelph, to determine the reproductive impact of a reciprocal translocation previously identified as t(Xp+;14q-). Blood samples were cultured and chromosome spreads were examined to identify carriers in the herd. Gonadal features of carrier boars and piglets and their age-matched normal counterparts were studied, and the reproductive history of carrier sows, including the number of breedings required for conception, mean litter size, prevalence of still births and malformations, and sex distribution among the piglets, was compared with that of normal (noncarrier) sows. Our observations on testicular histology confirmed that X-autosome translocation-carrier boars are sterile, and the analysis of reproductive data showed that the most striking effects of t(Xp+;14q-) on sows are the 50% increase in the number of breedings required for conception and the over 25% reduction in litter size compared with that of normal sows. The reproductive impact of this and similar translocations on the herd and on the swine industry in general is discussed.     

Temporal associations between low body condition,lameness and milk yield in a UK dairy herd

Previous work has hypothesised that cows in low body condition become lame. We tested this in a prospective longitudinal study. Body condition score (BCS), causes of lameness and milk yield were collected from a 600-cow herd over 44-months. Mixed effect binomial models and a continuous outcome model were used to investigate the associations between lameness, BCS and milk yield. In total, 14,320 risk periods were obtained from 1137 cows. There were 1510 lameness treatments: the most common causes of lameness were sole ulcer (SU) (39%), sole haemorrhage (SH) (13%), digital dermatitis (DD) (10%) and white line disease (WLD) (8%). These varied by year and year quarter. Body condition was scored at 60-day intervals. BCS ranged from 1 to 5 with a mean of 2.5, scores were higher in very early lactation but varied widely throughout lactation; approximately 45% of scores were <2.5. The key finding was that BCS < 2.5 was associated with an increased risk of treatment for lameness in the following 0–2 months and >2–4 months for all causes of lameness and also specifically for SU/WLD lameness. BCS < 2.5 was associated with an increased risk of treatment for SH in the following 0–2 months but not >2–4 months. There was no such association with DD. All lameness, SU/WLD, SH and DD were significantly more likely to occur in cows that had been lame previously, but the effect of BCS was present even when all repeat cases of lameness were excluded from the analysis. Milk yield was significantly higher and fell in the month before treatment in cows lame with SU/WLD but it was not significantly higher for cows that were treated for DD compared with non-lame cows. These findings support the hypothesis that low BCS contributes to the development of horn related claw lameness but not infectious claw diseases in dairy cows. One link between low BCS and lameness is a thin digital cushion which has been proposed as a trigger for claw horn disease. Cows with BCS 2 produced more milk than cows with BCS 2.5, however, this was only approximately 100 kg difference in yield over a 305-day lactation. Given the increased risk of lameness in cows with BCS 2, the direct costs of lameness and the small variability in milk yield by BCS, preventing cows from falling to BCS < 2.5 would improve cow welfare and be economically beneficial.