Implementation of Breed-Specific Traits for a Local Sheep Breed

In recent decades, a considerable number of local breeds have been replaced by high-yielding breeds for reasons of profitability. Many local breeds are now threatened by extinction and the loss of their native genetic diversity. The need to conserve breeds and their genetic diversity has a major importance due to the necessity for genetic change within and between populations. Novel approaches have to be explored and extended to maintain this genetic diversity. The aim of this study was the identification and implementation of breed-specific traits for a small, local sheep breed in northern Germany. The data comprised pedigree information, estimated breeding values (EBVs) of several conventional traits, and phenotypic information from a field experiment for two novel traits: 1) average daily gain under extensive circumstances (ADGE) and 2) ultrasonic measurements of muscle-fat ratio (UMFR). The experimental design included a dataset of 47 progeny from 14 pure-bred rams of German White-Headed Mutton (GWM). The methodical approach was divided into four parts: 1) the analysis of the breeding programme, 2) the identification of breed-specific traits, 3) the estimation and correlation of novel breeding values, and 4) the consequences of implementing these novel traits. Genetic parameters and correlations were conducted by applying linear mixed models. The estimates for the heritability (repeatability) were between 0.70 and 0.83 (0.42 and 0.46). The genetic correlation was positive (0.61) and in accordance with the phenotypic correlation (0.62). Average daily gain under intensive circumstances (ADGI) was moderately positive correlated with muscularity (0.60), as opposed to ADGE, which was moderately negative correlated with muscularity (-0.68). The EBV of ADGE was also moderately positive correlated with UMFR (0.64). Genetic response for ADGE enhanced to values of 481.09 g/day, 639.97 g/day, >700 g/day and >850 g/day for different selection intensity scenarios. Corresponding rates of inbreeding were 1.4%, 2.7%, 5.1%, and 7.9% after 10 years of selection. Genetic response for UMFR increased to 0.92, 1.34, 2.41, and >2.75, whereas remaining rates of inbreeding increased to 1.1%, 2.2%, 5.1%, and 7.9%. ADGI and ADGE were tendentially negatively correlated (-0.11), which strengthen the assumption of a biased ADGI. ADGE has a positive influence on meat-quality aspects (UMFR). Optimal use of reference sires with predefined selection intensity achieves genetic response for ADGE and UMFR with simultaneously acceptable rates of inbreeding.

Genetic Diversity and Ancestral History of the German Angler and the Red-and-White Dual-Purpose Cattle Breeds Assessed through Pedigree Analysis

Local cattle breeds continue to decline in numbers partly due to the use of high performing breeds in advanced production systems where genetic material of elite animals is widely spread. The objective of this study was to assess the within and across breed genetic diversity of the Angler and Red-and-White dual-purpose (DP) cattle breeds applying different inbreeding concepts. Classical and ancestral inbreeding coefficients were computed from pedigree data using the gene dropping method. Effective population size was calculated based on the increase of classical inbreeding, and based on ancestral inbreeding to obtain what was termed as ancestral effective population size. Furthermore, the effective number of founders and ancestors were computed to assess the disequilibrium of founder contribution in the reference populations. The analyses were performed separately for each breed and for a combined dataset. The Angler pedigree was more complete (88%) in the first parental generation but completeness declined with increasing pedigree depth. Average classical inbreeding coefficients of inbred individuals were 2.19%, 1.94% and 2.07%, while average Ballou’s ancestral inbreeding coefficients were 3.69%, 1.39% and 2.21% for the Angler, Red-and-White DP and the combined breed pedigree analyses, respectively. Ancestral history coefficient is a novel coefficient and its estimates were similar and strongly correlated to Ballou’s coefficients (r = 0.99, p < 0.001). The effective population size estimates ranged from 156 to 170 for the classical inbreeding based method, and as low as from 50 to 54 for the ancestral history coefficient based method. The effective number of founders and ancestors ranged from 310 to 532, and 90 to 189, respectively. Our results show that the Red Holstein breed is a key progenitor of the breed populations under study. This highlights cross breeding schemes introduced to improve the milk trait performance of the Angler and Red-and-White DP breeds some decades ago.