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Analysis of stayability in South African Angus cattle using a threshold model
A Maiwashe, KA Nephawe, HE Theron
South African Journal of Animal Science , 2009,
Abstract: The objectives of the study were to estimate genetic parameters for stayability in the South African Angus cattle and to compare the sire and animal threshold models. Data and pedigree information were obtained from the Integrated Registration and Genetic Information System of South Africa. Stayability was defined as a probability that a cow remained in the herd until four (STAY4), five (STAY5), six (STAY6), seven (STAY7) and eight years of age (STAY8), given that she was a dam. Cows that were in the herd by a specific age were assigned a “1” or a “0”, otherwise. The proportions of successful stayability were 0.63, 0.57, 0.49, 0.42, and 0.37 for STAY4, STAY5, STAY6, STAY7 and STAY8, respectively. Estimates of genetic parameters were obtained from sire and animal threshold models using AIREML algorithm. The model included the fixed effect of contemporary group and random effects of sire or animal genetic effect and the residual. Heritability estimates from the sire model were 0.26 ± 0.08, 0.26 ± 0.09, 0.30 ± 0.09, 0.24 ± 0.10 and 0.27 ± 0.11 for STAY4, STAY5, STAY6, STAY7 and STAY8, respectively. Corresponding estimates from the animal model were 0.20 ± 0.11, 0.20 ± 0.11, 0.20 ± 0.12, 0.18 ± 0.13 and 0.20 ± 0.14. Estimates from the sire and animal models were consistent. Results from the current study indicate that direct selection for stayability could be effective. However, the long generation interval required to obtain accurate estimates of genetic merit may slow genetic progress for stayability at older ages.
Non-linear model analysis of categorical traits related to female reproduction efficiency in beef cattle
T Rust, SJ Schoeman, J van der Westhuizen, JB van Wyk
South African Journal of Animal Science , 2009,
Abstract: The utilization of non-linear threshold models and linear animal models to estimate variance components for categorical reproductive traits in beef cattle was investigated. Three traits, retention (RET), stayability (STAY) and calf tempo (CT) were defined. The data set consisted of 36 880 Afrikaner beef cattle measurements recorded over a period of 10 years. After editing, the records of 7 746 females from 473 sires were available for the genetic parameter estimation for RET. The corresponding number of records for STAY and CT were 3 018 (243 sires) and 7 653 (465 sires), respectively. Using GFCAT, sire variances for RET, STAY and CT were estimated as 0.202, 0.072 and 0.114, respectively. With error variances pre-set to one, the heritability estimates on the underlying scale were calculated as 0.67, 0.27 and 0.41 for RET, STAY and CT, respectively. From the three traits analyzed in this study CT probably reflects the true fertility of the bull’s female progeny best.
The effect of herd of origin by year on post-weaning traits of young beef bulls at centralized testing centres in South Africa
KA Nephawe, A Maiwashe, HE Theron
South African Journal of Animal Science , 2006,
Abstract: The effects of herd of origin by year on the average daily gain (ADG), average daily feed intake (DFI), shoulder height (SDH) and scrotal circumference (SCR) of beef bulls at centralized test centres in South Africa were investigated using data of Bonsmara cattle. Data consisted of post-weaning traits of beef bulls tested between 1990 and 2003, with available weaning weight (WWT) and weaning management group information as well as weaning weights of their contemporaries. A multiple-trait animal model including ADG, DFI, SDH and SCR, together with WWT was used. The model for WWT (adjusted to 205 days of age and age of dam by sex of calf classes) included the fixed effect of management group and random effects of direct additive genetic and dam effects, while the model for post-weaning traits included fixed effects of test group and age of the bull at the end of test (fitted as linear and quadratic regressions) and random effects of direct additive genetic and herd of origin by year (HY) effects. Variance components were estimated using REML procedures. Heritability estimates were 0.27, 0.34, 0.36, 0.51 and 0.46 for WWT, ADG, DFI, SDH and SCR, respectively. The contribution of HY effects to the phenotypic variance of ADG, DFI, SDH and SCR were 9%, 10%, 6% and 5%, respectively. Inclusion of HY effect resulted in the re-ranking of sires, with rank correlations ranging from 0.86 to 0.98 among the top sires, across traits. These results suggest that the HY effect should be included in the model for the national genetic evaluation of post-weaning traits of beef bulls measured at centralized testing centres in South Africa. South African Journal of Animal Science Vol. 36(1) 2006: 33-39
Genetic parameters for reproductive traits in a beef cattle herd estimated using multitrait analysis
R.R. Van der Westhuizen, S.J. Schoeman, G.F. Jordaan, G.F. Jordaan, J.B. Van Wyk
South African Journal of Animal Science , 2001,
Abstract: The object of this study was to estimate heritabilities and genetic correlations for reproductive traits in a composite multibreed beef cattle herd using multitrait analysis. A REML procedure fitting a multitrait animal model was used to analyse data. Heritabilities and genetic correlations for calving interval (CI), calving date (CD), calving date with a penalty score (CDP) and age at first calving (AFC) were estimated as traits of the dam. The estimated heritabilities for CI, CD, CDP and AFC obtained in this study were 0.01, 0.04, 0.06 and 0.40 respectively with a repeatability of 0.07, 0.12 and 0.13 for CI, CD and CDP. Genetic correlations between traits varied from low to moderate, except for high correlations between CD and CDP (0.98), CI and CD (0.75) and between CI and CDP (0.79). Heritabilities, genetic correlations and repeatabilities of CD and CDP obtained in this study suggest that CD and CDP are the same traits and that selection for CDP rather then for CD does not have any additional advantages. Due to the additional advantages of CD over CI and the fact that CD is a less biased measurement of the female reproductive complex, CD and AFC (because of its high heritability) may be considered as selection criteria for improvement of reproduction in beef cattle herds. (South African Journal of Animal Science, 2001, 31(1): 41-48)
Influence of reproduction traits and pre-weaning growth rate on herd efficiency of different beef breed types in an arid sub-tropical environment
I du Plessis, LC Hoffman, FJ Calitz
South African Journal of Animal Science , 2006,
Abstract: The efficiency of Simmentaler cross (SX), Bonsmara cross (BX), Afrikaner (AF) and Nguni (NG) cowherds to produce weaner calves under natural sweetveld conditions was investigated. The respective cowherds were selected to differ with regard to frame size (SX > BX > AF > NG). The AF cows, young (13 to 15 months old) heifers and herd had significantly lower pregnancy rates than the SX, BX and NG cows, young heifers and herds. The weaning rate for NG was significantly higher (15%) than SX, and although not significant, it was still 5 and 8% respectively higher than BX and AF. Weaning weight and pre-weaning growth parameters differed significantly between breed types (SX > BX > AF > NG). Cow efficiency was significantly lower for the AF cows than for the SX, BX and NG cows. The NG herd was more efficient than the other three herds, while the AF herd was the least efficient. Differences in herd efficiency were mainly due to differences in the reproduction rates of the respective herds. The reproduction and calf survival rates were the most important production traits that affected herd efficiency. Management practices should be adapted to maximize the reproduction rate of the females, including the young heifers, to maximise herd efficiency. South African Journal of Animal Science Vol. 36(2) 2006: 89-98
Connectedness among herds of beef cattle bred under natural service
Joaquim Tarrés, Marta Fina, Jesús Piedrafita
Genetics Selection Evolution , 2010, DOI: 10.1186/1297-9686-42-6
Abstract: The CDs of comparisons among herds were calculated using a sampling-based method that estimates empirical variances of true and predicted breeding values from a simulated n-sample. Once the CD matrix was estimated, a clustering method that can handle a large number of comparisons was applied to build compact clusters of connected herds of the Bruna dels Pirineus beef cattle. Since in this breed, natural service is predominant and there are almost no links with reference sires, to estimate CDs, an animal model was used taking into consideration all pedigree information and, especially, the connections with dams. A sensitivity analysis was performed to contrast single-trait sire and animal model evaluations with different heritabilities, multiple-trait animal model evaluations with different degrees of genetic correlations and models with maternal effects.Using a sire model, the percentage of connected herds was very low even for highly heritable traits whereas with an animal model, most of the herds of the breed were well connected and high CD values were obtained among them, especially for highly heritable traits (the mean of average CD per herd was 0.535 for a simulated heritability of 0.40). For the lowly heritable traits, the average CD increased from 0.310 in the single-trait evaluation to 0.319 and 0.354 in the multi-trait evaluation with moderate and high genetic correlations, respectively. In models with maternal effects, the average CD per herd for the direct effects was similar to that from single-trait evaluations. For the maternal effects, the average CD per herd increased if the maternal effects had a high genetic correlation with the direct effects, but the percentage of connected herds for maternal effects was very low, less than 12%.The degree of connectedness in a bovine population bred by natural service mating, such as Bruna del Pirineus beef cattle, measured as the CD of comparisons among herds, is high. It is possible to define a pool of animals
Identification of the recently described new type of bovine papillomavirus (BPV-8) in a Brazilian beef cattle herd
Claus, Marlise P.;Lunardi, Michele;Alfieri, Alice F.;Sartori, Daniele;Fungaro, Maria Helena P.;Alfieri, Amauri A.;
Pesquisa Veterinária Brasileira , 2009, DOI: 10.1590/S0100-736X2009000100003
Abstract: bovine papillomavirus type 8 (bpv-8) was first detected and described in teat warts as well as in healthy teat skin from cattle raised in japan. the entire viral genome was sequenced in 2007. additionally, a variant of bpv-8, bpv-8-eb, was also identified from papillomatous lesions of a european bison in slovakia. in brazil, despite the relatively common occurrence of bpv infections, the identification and determination of viral types present in cattle is still sporadic. the aim of this study is to report the occurrence of the recently described bpv-8 in brazil. the virus was identified in a skin warts obtained from a beef cattle herd located in parana state, southern brazil. the papilloma had a macular, non-verrucous gross aspect and was located on the dorsal thorax of a cow. polymerase chain reaction (pcr) was performed using generic primers for partial amplification of l1 gene. the obtained amplicon (480bp) was cloned and two selected clones were sequenced. the nucleotide sequence was compared to existing papillomaviral genomic sequences, identifying the virus as bpv type 8. this study represents the first report of bpv-8 occurrence in brazil, what suggests its presence among brazilian cattle.
Herd and within-herd BoHV-1 prevalence among Irish beef herds submitting bulls for entry to a performance testing station
L O'Grady, R O'Neill, DM Collins, TA Clegg, SJ More
Irish Veterinary Journal , 2008, DOI: 10.1186/2046-0481-61-12-809
Abstract: Infectious Bovine Rhinotracheitis (IBR), caused by bovine herpes virus 1 (BoHV-1), may result in various clinical consequences, including severe respiratory disease, venereal disease with reduced reproductive performance and abortion. Like other herpes viruses, BoHV-1 also results in lifelong latent infections. The virus may be spread within cattle populations via contact, aerosol, fomites and via infected semen, ova or embryos [16].There are substantial economic consequences associated with respiratory disease as a result of BoHV-1 [9]. In addition, BoHV-1-free status is an important issue in the international trade of live animals and some animal products. As an international standard, all semen used in artificial insemination must be sourced from BoHV-1 seronegative bulls [10]. Furthermore, BoHV-1 has been eradicated from a number of countries within Europe (including Austria, Denmark, Finland, several Italian provinces, Norway, Sweden and Switzerland) [1]. In some other countries (France, Germany, the Netherlands), eradication programmes are in place [1]. Eradication strategies have been based on a foundation of improved herd and regional bio-security, in conjunction with a test and slaughter policy [11]. BoHV-1 status has emerged as a barrier to within-community trade, with EU directives 64/432, 88/407 and 93/60 [3-5] allowing member states to stipulate requirements to be met for the importation of cattle, semen and embryos [17]. In some countries where infection is endemic, the use of marker vaccination (gene deleted vaccines) has been introduced to reduce herd prevalence, whilst still allowing the differentiation between wild virus exposure and vaccination. In Ireland, only the use of marker vaccines is permitted, but there is currently no national BoHV-1 control programme in place.In early 2007, an outbreak of clinical IBR occurred at a beef bull performance testing station in Ireland. At this performance testing station, the best beef bulls would be identif
Estimates of repeatability and heritability of productive and reproductive traits in a herd of Jersey cattle
Roman, R.M.;Wilcox, C.J.;Martin, F.G.;
Genetics and Molecular Biology , 2000, DOI: 10.1590/S1415-47572000000100021
Abstract: estimates of the repeatability and heritability of 19 measures of performance in jersey cows were obtained using an animal model with a relationship matrix and a derivative-free restricted maximum likelihood algorithm. the data consisted of 935 records for 374 cows by 69 sires over the period 1969-1987. the estimates were similar to those obtained by ordinary least squares methods reported for the same data set and in other studies, but had smaller error variances. a likelihood ratio test showed agreement between these heritability estimates and those in the literature. the heritability estimates of milk, fat, protein, lactose-mineral, solids-not-fat, and total solids yields were about 0.25; for the corresponding percentages, and for the protein to fat and solids-not-fat to fat ratios, the estimates were 0.50. heritability estimates were 0.10 or less for the time from parturition to first breeding and for three measures of somatic cell counts. these estimates of heritability in a dairy cattle population in a subtropical environment were not different from those of populations in temperate climates.
Estimates of repeatability and heritability of productive and reproductive traits in a herd of Jersey cattle
Roman R.M.,Wilcox C.J.,Martin F.G.
Genetics and Molecular Biology , 2000,
Abstract: Estimates of the repeatability and heritability of 19 measures of performance in Jersey cows were obtained using an animal model with a relationship matrix and a derivative-free restricted maximum likelihood algorithm. The data consisted of 935 records for 374 cows by 69 sires over the period 1969-1987. The estimates were similar to those obtained by ordinary least squares methods reported for the same data set and in other studies, but had smaller error variances. A likelihood ratio test showed agreement between these heritability estimates and those in the literature. The heritability estimates of milk, fat, protein, lactose-mineral, solids-not-fat, and total solids yields were about 0.25; for the corresponding percentages, and for the protein to fat and solids-not-fat to fat ratios, the estimates were 0.50. Heritability estimates were 0.10 or less for the time from parturition to first breeding and for three measures of somatic cell counts. These estimates of heritability in a dairy cattle population in a subtropical environment were not different from those of populations in temperate climates.
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