A.M. Silvestre

Diagnosis, genetic control and preventive management of canine hip dysplasia: a review.

Despite expensive screening and breeding programmes, hip dysplasia (HD) continues to be one of the most common orthopaedic diseases in dogs. The vast majority of dogs afflicted with HD show minimal to no clinical signs, but it can also be a highly debilitating condition for both working and pet dogs. Hip joint laxity is considered a major risk factor for the development of degenerative joint disease and a definitive diagnosis is made if characteristic signs are evident on a ventrodorsal view of the pelvis. Early prediction of the condition can be made using stress radiographic techniques to evaluate the passive hip laxity. The diagnosis of HD may be used for the purpose of selecting breeding stock or to decide on the best treatment approach. Breeding programmes based on individual dog phenotypes have been ineffective and a selection procedure based on breeding value (BV) estimation is recommended. Traditional conservative and surgical treatment approaches are reserved for dogs with overt clinical signs of the disease but such treatments can be expensive and aggressive, and are often ineffective in eliminating clinical signs or subluxation and in preventing the development of degenerative joint disease. The implementation of breeding programmes based on BVs and further research into early prediction/diagnosis of HD and effective preventive treatment approaches are essential.

PASSIVE HIP LAXITY IN ESTRELA MOUNTAIN DOG - DISTRACTION INDEX, HERITABILITY AND BREEDING VALUES

Two hundred and fifteen Estrela Mountain Dogs (EMD) were examined using the PennHIP method between 2002 and 2006. Passive hip laxity (PHL) was estimated calculating the distraction index (DI). Pedigree information was obtained from the Portuguese Kennel Club. The heritability and breeding values were estimated using the linear Animal Model. The DI, using as reference the worst joint of each animal, ranged from 0.15 to 1.12 (0.55 +/- 0.19). The PHL was equal in right and left sides, and was higher in females than in males (P > 0.05 and P <0.01 in the t-test, respectively). The estimated heritability was 0.83 +/- 0.11. The mean breeding values for PHL were stable in EMD born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm high PHL in breeds with high prevalence and severity of canine hip dysplasia. The high heritability indicates that the DI could be reduced in the breed if PHL were used as a selection criterion. The early favourable evolution of DI breeding values could be related with the increase of voluntary radiographic hip screening in the last years, and the subsequent introduction of hip quality as a breeding criterion.

Somatic cell score genetic parameter estimates of dairy cattle in Portugal using fractional polynomials.

Milk somatic cell count is an indicator trait for mastitis resistance. Genetic parameters for somatic cell score in the Portuguese Holstein-Friesian population were estimated by modeling the pattern of genetic correlation over the first 3 lactations (days in milk) with a random regression model. Data records from the first 3 lactations were from the national database of the Portuguese Holstein Association herds. Heritability estimates ranged from 0.05 at the beginning of the lactation for the 3 lactations, to 0.07 at the end of the lactation period for the first and third lactations, to 0.09 for the second lactation. This increase in the heritability values was due to an increase in the genetic variance and a decrease in the residual variances. Genetic correlations evaluated for monthly time points were high (0.65 to 0.99) for all 3 lactations, whereas phenotypic correlations were much less than the genetic correlations (0.13 to 0.62).

Estimation of carcase composition of goat kids from joint dissection and conformation measurements

Abstract The aim of this study was to develop equations to estimate percentages and carcase tissue weights of suckling goat kids by using cold carcase weight (CCW), carcase conformation measurements and joints tissue as independent variables. Carcases dissection data from 55 goat kids were used for regression analysis. Leg and shoulder muscle weight showed the highest positive correlations with carcase muscle weight (r = .98). Shoulder tissue weight showed the highest correlation with carcase bone weight (r = .97), carcase subcutaneous fat weight (r = .95) and carcase intermuscular fat weight (r = .95). Also, shoulder tissue percentage showed the highest correlation with carcase muscle percentage (r = .93) and carcase subcutaneous fat percentage (r = .90). CCW explained 95.9% of muscle weight carcase variability. The percentage of the variation explained in other tissues (bone, subcutaneous and intermuscular fat) was lower, but not negligible (89.6%, 60.7% and 48.7%, respectively). Chest circumference and carcase compactness presented the highest correlation with weight of carcase tissues, especially with muscle weight (r = .93), bone weight (r = .93 and .89, respectively), subcutaneous fat (r = .71 and .79) and intermuscular fat weight (r = .68 and .67). The results of this study support the conclusion that the shoulder tissue composition allows accurate estimation of the carcase composition. Also, CCW, chest circumference and carcase compactness measurements were good predictors of the weight of carcase tissues in goat kids, with the advantage to be non-destructive and easy to obtain.