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Members of the Federation of Boxer Clubs in Southern Africa (FBCSA) have participated in official recording for many years. The aim of the study was to estimate genetic parameters and trends for preweaning survival and to assess inbreeding in the South African Boxer, based on performance and pedigree data. Fitness records were included from 2138 litters recorded between 1988 and 2012 and pedigree information of 32 029 Boxer dogs recorded from 1950 to 2012. The average litter size was 6.14 ± 2.43. More male puppies were born per litter (3.23 ± 1.79) than female puppies (2.91 ± 1.72), with an increase in the proportion of males in larger litter sizes. Heritability values of 0.23 ± 0.08 and 0.25 ± 0.08 were estimated for litter size (LS) and number of puppies alive at two weeks after birth (NA), respectively. Litters larger than five tended to have more puppies born dead or with low survivability. Number of puppies born dead or that died within two weeks after birth increased from 0.43/litter at first parity to 0.82/litter at fifth parity, with a substantial increase of 2.25/litter with low survivability at seventh parity. Average inbreeding levels of the Boxer breed were above 10%, with an inbreeding rate of 0.14%/year since 1982. These results indicate that FBCSA should focus on lowering the levels of inbreeding by avoiding mating closely related animals. The complete recording of fitness traits is encouraged for effective genetic management of the breed. [ABSTRACT FROM AUTHOR]

The SA Dairy Swiss population could not previously be incorporated into the National Dairy Genetic Evaluation System, owing to inadequate population numbers and data structures. However, in recent years participation in Milk Recording has improved sufficiently to allow for genetic evaluation of the population. The aim of the study was therefore to estimate genetic parameters for the SA Dairy Swiss for production traits and somatic cell score in order to estimate breeding values routinely from the National Dairy Genetic Evaluation System. After editing procedures, a dataset of 25 621 test-day records for milk, butterfat and protein yields and a dataset of 10 438 test-day records for somatic cell count were obtained for further analysis. (Co)variance components for milk (kg), butterfat and protein yields (kg), as well as for somatic cell score, were estimated using a fixed regression multi-lactation animal model, based on test-day records of the first three lactations. Records from the various lactations were included as repeated measures. A multi-trait evaluation was performed for the production traits, while a single trait evaluation was done for somatic cell score, using the software package VCE4. Heritability estimates were 0.19 for milk, 0.16 for butterfat, and 0.16 for protein yields. The heritability estimate for somatic cell score was lower, at 0.07. The genetic correlations between the production traits were lowest for milk and butterfat (0.83), and were similar for milk and protein (0.94) and butterfat and protein yields (0.94). These values compare favourably with those of the other South African dairy breeds, based on the same model. The (co)variances were then implemented for estimation of breeding values for the SA Dairy Swiss population. Genetic trends were favourable for milk production traits with milk yield, butterfat and protein yields increasing by 25.13 kg/year, 0.96 kg/year and 0.79 kg/year, respectively; while the trend for somatic cell score was unfavourable, increasing by 0.86 units/year, since 1983. The SA Dairy Swiss could therefore be incorporated into the National Dairy Genetic Evaluation System of South Africa, using these covariance components and model. [ABSTRACT FROM AUTHOR]

Calving interval (CI) is a fertility trait that can be used in selection programmes to minimize the negative effects that selection for production have on fertility. CI can be derived from milk recording data, therefore this fertility trait can easily be implemented in the National Dairy Genetic Evaluations of South Africa. The aim of this study was to estimate genetic parameters for CI for estimation of breeding values and genetic trends to enable South African dairy breeders to assess and select for improved fertility. Breeds included in the study were Ayrshire, Guernsey, Holstein and Jersey. Genetic parameters and trends were based on the first three CIs for all breeds. The genetic software package, VCE4, was used to estimate genetic parameters for CI. Heritabilities ranged from 0.011 for CI1 to 0.069 for CI2, both for the Guernsey breed. Genetic correlations ranged from 0.606 between CI2 and CI3 for the Guernsey breed, to 0.810 between CI1 and CI2 for the Ayrshire breed. Breeding value estimation was done using the genetic software package, PEST. The estimated breeding values were combined into an index value, using weighting factors based on the amount of information available for each trait. Genetic trends were calculated by averaging the CIindices of measured cows per year of birth. These genetic trends indicated that CI increased genetically for all breeds. The genetic parameters will now be implemented for the estimation of CI breeding values, which can be included in selection programmes for improvement of fertility of dairy breeds in South Africa. [ABSTRACT FROM AUTHOR]

Procedures have been developed for calculation of a Persistency Index for South African dairy breeds. This index is based on the Canadian Persistency Index, which is simple and easy to understand. Data used in this study were test-day records of the first three lactations, as included in the National Dairy Genetic Evaluations of South Africa, of the Ayrshire, Guernsey, Holstein and Jersey breeds. Interpolation, using the Wilmink curve, was done on these test-day records to calculate 60-day and 280-day yields for each cow and lactation. Variance components have been estimated for these yields to be used in breeding value estimations, using bivariate evaluations and a repeatability model. To obtain independence of persistency from total milk yield, 305-day milk yield estimated breeding values were included as covariates in the genetic model for estimation of breeding values for 60- and 280-day yields. The Persistency Index will be released for sires with progeny following each national dairy genetic evaluation, allowing the South African dairy industry to select for changes in persistency in future. [ABSTRACT FROM AUTHOR]

South Africa implemented test-day models for genetic evaluations of production traits, using a Fixed Regression Test-Day Model (FRTDM), which assumes equal variances of the response variable at different days in milk, the explanatory variable. Data at the beginning and at the end of lactation period, have higher variances than tests in the middle of the lactation. Furthermore, first lactations have lower mean and variances compared to second and third lactations. This is a deviation from the basic assumptions required for the application of repeatability models. A modification was therefore implemented to reduce the effect of deviating from this assumption. Test-day milk, butterfat and protein yield records of Jersey cows, participating in the South African Milk Recording Scheme, were therefore pre-adjusted such that the variances are on the same scale. Variance components estimated using the adjusted records were higher than using unadjusted records. Convergence of breeding value estimation is reached significantly faster when using adjusted data (± 4000 iterations) compared to unadjusted records (± 15 000 iterations). Although cow and bull rankings were not influenced much, significant changes in breeding values for individual animals and genetic trends of especially young animals, were found. [ABSTRACT FROM AUTHOR]

A comparison of breeding values and genetic trends of production traits from two models is made. One set of breeding values and trends was estimated by the September/October 2003 South African National Genetic Evaluation, using a Lactation Model (LM). The other set was obtained in the 2004 South African National Genetic Evaluation, using a Fixed Regression Test-day Model (TDM). This comparison is made for Ayrshire, Guernsey, Holstein and Jersey cows participating in the South African Dairy Animal Improvement Scheme. Specific differences between the two models were documented, with differences in statistical methodology and inclusion of test-day records of the first three parities in the TDM vs. only first lactation 305-day yields in the LM, as the main differences. Significant reranking of especially cows and unproven sires occurred between the models. Genetic trends of the TDM were not as steep as those from the LM, as the trait that was selected was first lactation yield, while the TDM trends reflect genetic progress over the first three parities. [ABSTRACT FROM AUTHOR]

Variance components and breeding values of production traits and somatic cell score of South African Guernsey, Ayrshire, Holstein and Jersey breeds have been estimated using a multi-lactation repeatability test-day model, including tests of the first three lactations as repeated measures and fitting the permanent environmental effect across lactations. Multitrait evaluations were done for the production traits (milk, butterfat and protein) and single trait evaluations for somatic cell score. Heritability estimates were comparable with yield and somatic cell score estimates obtained by test-day models from other countries (17-24% for milk yield; 10-13% for butterfat yield; 14-19% for protein yield and 6-8% for somatic cell score). Proofs of qualifying sires were sent to the International Bull Evaluation Service (INTERBULL) for participation in the March 2005 test runs. Genetic correlations between South Africa and other participating countries, estimated by INTERBULL, compared well with those amongst the other participating countries. Trend validation tests were successful using this methodology for all traits and breeds except for somatic cell score of the Guernsey breed, due to insufficient data for this trait. South Africa can now participate in routine INTERBULL evaluations to obtain Multiple Across Country Evaluation (MACE) breeding values, using this methodology. [ABSTRACT FROM AUTHOR]

Two fixed regression testday models were applied for variance component estimation and prediction of breeding values for somatic cell score, using testday records of the first three lactations of South African Holstein and Jersey cows. The first model (ML-model) considered the testdays of the different lactations as different traits in a multiple-trait animal model and the second analysis (RM-model) treated later lactation records as repeated measures of the first lactation. Heritabilities from the RM-model were more in the range of literature estimates compared to that of the ML-model, i.e. 0.19 ± 0.003 for the Holstein breed and 0.18 ± 0.003 for the Jersey breed. Rank correlations indicated that minor changes occur in the ranking of proven sires between breeding values obtained from the ML- and RM-models. Although genetic correlations between parities are not unity, the RM-model estimates more competitive variances and requires extensively less computer time to predict breeding values compared to the ML-model and are therefore recommended for breeding value estimation on a national basis. [ABSTRACT FROM AUTHOR]

Methodology has been developed to implement testday models in the national genetic evaluation of dairy breeds for production traits in South Africa. Positive definite covariance matrices have been estimated, using multitrait, multi-lactation, fixed regression testday BLUP animal models, including testday records of the first three lactations as repeated measures for the Holstein and Jersey breeds. Heritability estimates were 0.40 ± 0.007 for milk yield, 0.25 ± 0.006 for butterfat yield and 0.37 ± 0.006 for protein yield for the Holstein breed and 0.39 ± 0.004 for milk yield, 0.21 ± 0.002 for butterfat yield and 0.34 ± 0.002 for protein yield for the Jersey breed. These estimates are well in the range of estimates reported by countries participating in INTERBULL evaluations. [ABSTRACT FROM AUTHOR]

In South Africa, the Dairy Swiss breed, which originated in Switzerland, consists of 27 breeders and 1135 breeding cows. Pedigree information on the breed was analysed to determine its effective population size (Ne) and rate of inbreeding. The rate of inbreeding was 0.08% per year and 0.38% per generation. It was estimated that in 2008, over 90% of the animals were inbred. This is within the acceptable recommendation for an effective population size of 50 - 100, with an Ne value of 89. However, the high percentage of inbred animals may start to have a detrimental impact on the effective population size and breeders need to exercise caution in their breeding decisions. [ABSTRACT FROM AUTHOR]

Data obtained from the Friesian Horse Studbook of Southern Africa and Friesian Horse Breeders' Society of South Africa were analyzed to describe and evaluate the population regarding inbreeding and morphological body measurements. Eight different body measurements (height at withers, height of back, height of croup, body length, length of cannon forelimb and hind limb, circumference of cannon bone fore- and hind limb) recorded on 232 horses were included for analyses. The pedigrees of 696 horses were used for estimation of inbreeding coefficients. A total of 25% of the horses included in the data was inbred, with inbreeding coefficients ranging from 0.07% to 27.8%. A positive trend in the average inbreeding per year was observed, but the rate of inbreeding was relatively low. Recording of pedigree information will be essential for long-term evaluation of inbreeding in the Friesian Horse and the recording of objective body measurements is recommended for inclusion in selection programs. [ABSTRACT FROM AUTHOR]

Pedigree information on the registered South African Ayrshire (n = 47 116), Guernsey (n = 18 766), Holstein (n = 892 458) and Jersey (n = 314 403) breeds was analyzed to determine the rate of inbreeding and effective population sizes for the period 1960 to 2003. Inbreeding coefficients were calculated using the Animal Breeder's Tool Kit. The mean inbreeding coefficients for 2003 were 2.02%, 2.04%, 2.30%, and 3.05% for the Ayrshire, Guernsey, Holstein and Jersey, respectively. The corresponding rates of inbreeding per year were 0.05%, 0.05%, 0.06%, and 0.07% indicating that inbreeding is accumulating at a slightly higher rate in Jersey compared to the other three breeds. However, the rates of inbreeding in the current study are still considerably lower than the acceptable rate of less than 0.5% per year. Estimates of effective population sizes were 148, 165, 137, and 108 for the Ayrshire, Guernsey, Holstein and Jersey, respectively. Results indicate that the impact of inbreeding on genetic variability is still minimal. However, the impact of inbreeding on phenotypic performance on traits of economic importance was not investigated in the current study and should therefore receive future consideration. [ABSTRACT FROM AUTHOR]