Canadian Swine Research Articles

Estimation of genetic and phenotypic trends for litter size in canadian yorkshire and landrace swine

Litter size in swine, although lowly heritable, has been receiving increasing interest especially with the availability of computer programs to allow estimation of genetic merit for this trait using family information. Genetic changes in a trait over time can be monitored by estimating best linear unbiased prediction (BLUP) of breeding value for individuals exhibiting the trait. Data from a recording programme within a Canadian province allowed estimation of genetic and phenotypic trends for three measures of litter size.Data from purebred Yorkshire and Landrace litters were obtained from the Quebec Record of Performance Sow Productivity Program. First parity litters born between 1977 and 1987 were analysed for total numbers born, numbers born alive and numbers weaned. Data were edited to include only herds with ten or more litters in Yorkshire and 40 or more litters in Landrace. Also, in order to reduce the number of records further, due to computing limitations, a sow was only allowed one daughter per full-sib family. A total of 2024 Yorkshire gilts (from 467 sires and 1539 dams) and 1920 Landrace gilts (from 421 sires and 1436 dams) provided records.

INTERRELATIONSHIPS BETWEEN HEALTH ENVIRONMENT AND GENETIC AND PHENOTYPIC PERFORMANCE OF PIGS FOR GROWTH RATE AND BACKFAT

Data from the Canadian Swine Genetic Evaluation Program for Yorkshire and Landrace pigs born between July 1982 and December 1984 were used to compare herds of different health classification (basic, good and excellent) for environmental and genetic levels and annual rates of environmental and genetic change in days and backfat thickness to 90 kg. There were 35 basic, 34 good and 20 excellent herds represented. Environmental differences between excellent and basic herds were −7.2 ± 3.0 d and 0.72 ± 0.31 mm backfat and between excellent and good herds were −5.3 ± 3.0 d and 0.87 ± 0.31 mm backfat. Faster growth rate in the excellent environment was accompanied by increased fatness. Genetic differences between excellent and basic herds were 1.2 ± 0.4 d and −0.45 ± 0.12 mm backfat and between excellent and good herds were 0.1 ± 0.4 d and −0.30 ± 0.12 mm backfat. Selection differentials were greatest for backfat and least for days in excellent herds and vice versa in basic herds. Rates of genetic change in days to 90 kg were equal across health classification, but excellent herds had greater rates of genetic improvement in backfat than basic or good herds. Data were also obtained from the New Hamburg, Ontario test station on boars that completed performance test between 1984 and 1985. Health classification of herd of origin had no effect on performance of boars for average daily gain or feed conversion at the test station. Effects of health classification of herd of origin on backfat were significant (P < 0.05), but reflected genetic differences between these types of herds rather than carry over environmental effects. However, the percentage that failed to complete the station test was 11.5 for boars from excellent herds, compared to 9.9 and 8.1 for boars from basic and good herds, respectively (P < 0.10). Key words: Health environment, genetic level, test station, backfat, growth rate, selection

A note on the changes in leg weakness in pigs after being transferred from confinement housing to pasture lots

It is a popular belief, supported by several scientific studies (Vaughan, 1971; McPhee and Laws, 1976; Fredeen and Sather, 1978; Sather and Fredeen, 1982) that leg weakness will diminish in young stock of breeding age after they are transferred from confinement housing to pasture lots. However, Nakano, Aherne and Thompson (1981) working with boars from the Canadian Swine ‘Record of Performance’ (ROP) testing programme found that no improvement in gait resulted after the animals were transferred from confinement housing with solid concrete flooring to pasture lots. The number of animals in the study was limited. All of these reports dealt only with the recovery of pigs from leg weakness and did not include pigs with sound legs at the beginning of the pasture period (approx. 90 kg live weight).

A Survey of Productivity and its Component Interrelationships in Canadian Swine Herds

A Survey of Productivity and its Component Interrelationships in Canadian Swine Herds

LIVE ANIMAL EVALUATION OF TWO ULTRASONIC PROBES AS ESTIMATORS OF SUBCUTANEOUS BACKFAT AND CARCASS COMPOSITION IN PIGS

Ultrasonic probe data recorded on a total of 186 Lacombe barrows and gilts were obtained by two operators using the Krautkramer USM2 and Scanoprobe 731A. Backfat measurements were taken, prior to marketing, at approximately 90 kg at locations 5 cm off either side of the midline on the mid-back and on the loin, corresponding to Canadian Swine ROP policy. These measurements were then repeated on the carcass. Correlations between average probe backfat (PF) and average probe site carcass fat (CF) were similar for both operators using the USM2 (r = 0.78, 0.84) and the 731A (r = 0.78, 0.82). The two units accounted for similar proportions of the variances of percent carcass lean (R2 = 0.35, 0.35) and of percent carcass fat (R2 = 0.45, 0.47). Consideration of the effects of sex and weight increased the R2 value by 2–6% for percent carcass lean and 6–7% for percent carcass fat. The USM2 (PF = 19.2, 20.4 mm) produced results in closer agreement with CF (20.0 mm) than did the 731A (PF = 18.9, 19.4 mm), for each operator. However, greater bias appeared to be associated with the USM2 than with the 731A, for measuring PF as an estimator of CF. Overall, it was judged that both machines were equivalent in their ability to measure subcutaneous backfat and to predict carcass composition from the live animal. Considering the additional cost of the USM2, purchase of this machine could not be justified on the basis of performance. Key words: Swine, ultrasonic probes, backfat, live animal evaluation, carcass evaluation

Vomiting and wasting disease, a coronavirus infection of pigs.

In 1957, an epizootic disease of nursing pigs characterized by high morbidity, vomiting, anorexia, constipation and severe progressive emaciation was observed in Canadian swine herds.1 In acute cases, vomiting and severe depression were the only symptoms noted before death. More frequently the disease tended to become chronic. The affected suckling pigs became emaciated and usually died of starvation after a few weeks. Pigs that survived were permanently stunted. The condition was called “vomiting and wasting disease” because of its salient characteristics.KeywordsDorsal Root GanglionTrigeminal GanglionMedulla OblongataVagal NerveBreeding FarmThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Alternative Market Weights for Swine. I. Feedlot Performance

Summary The current interest of Canadian swine producers in increasing market weight can be attributed to improved swine production from advances in management and genetics, increased fixed costs of production and revision of the hog grading index. Data on 286 market pigs slaughtered between 72.5 and 140 kg indicated linear increases of feedlot days, backfat measurements, carcass weight and dressing percentage as market weight increased. Average daily gain remained constant relative to market weight. Nonlinear effects for these traits, while statistically significant, did not substantially contribute to the multiple correlation coefficient. Furthermore, these nonlinear effects were attributed to puberty of the gilt. As expected, barrows had superior growth rates but inferior fat measurements in comparison to gilts. Dressing percentage was equivalent in both sexes, and gilts excelled in carcass index only at 78 kilograms. In general, these data, support the marketing of animals at 100 to 110 kg to produce 78 to 86-kg carcasses.

INBREEDING AND RELATIONSHIP FOR THREE BREEDS OF PIGS IN CANADA

In a calf with dyspnea, a mass located dorsal to the pharynx was visualized by ultrasonography. Magnetic resonance imaging (MRI) revealed a severe enlargement of the left medial retropharyngeal lymph node, compatible with an abscess. This is the first reported case of MRI use in bovine upper respiratory disease.

A REVIEW OF CANADIAN HELMINTHOLOGY: I. THE PRESENT STATUS OF KNOWLEDGE OF THE HELMINTH PARASITES OF DOMESTICATED AND SEMIDOMESTICATED MAMMALS AND ECONOMICALLY IMPORTANT BIRDS IN CANADA, AS DETERMINED FROM WORK PUBLISHED PRIOR TO 1933

A review is made of all previous records of Trematoda, Cestoda and Nematoda found in Canadian horses, cattle, sheep, swine, deer and buffalo, dogs and cats, foxes, miscellaneous fur-bearers, poultry and game birds.These records are taken from papers published in various forms which claim identification of the parasites found, and are here published as check lists following an introduction and a semihistorical review of Canadian helminthology.

A REVIEW OF CANADIAN HELMINTHOLOGY: II. ADDITIONS TO PART I, AS DETERMINED FROM A STUDY OF PARASITIC HELMINTHS COLLECTED IN CANADA

The author adds to Part I further records of Trematoda, Cestoda and Nematoda of Canadian horses, cattle, swine, sheep, poultry, game birds and miscellaneous hosts. These appear as check lists, the specimens having been identified by the author and deposited in helminthological collections. Parts I and II summarize the extent of knowledge concerning the distribution and prevalence of these parasites in Canada, and a bibliography covering these papers is herewith included.