Breeding goals and selection criteria for intensive and semi-intensive dairy goat system in Brazil

Defining smallholders' breeding objectives for common Tigray highland sheep in Northern Ethiopia

A sound breeding objective is a basis for genetic improvement in the overall economic merit of farm animals. This study aimed to define smallholders' sheep breeding objectives using a conjoint-based choice experiment and bio-economic model. Multinomial logistic regression analysis showed differences (p < 0.001) among the derived weights allocated by farmers to body size, twining rate, mothering ability, libido, tail type, colour and lambing interval which formed the high priority traits. The likelihood values of farmer's top three preferred traits for ram were body size (0.659 ± 0.009), tail type (0.325 ± 0.016) and libido (0.247 ± 0.016) while body size (0.459 ± 0.010), twining rate (0.313 ± 0.010) and mothering ability (0.261 ± 0.010) were more preferred traits for selection of breeding ewes. Conjoint-based choice experiment and bio-economic model indicated that live body weight at 6 months of age, twining rate (litter size) and mothering ability (preweaning lamb survival) were the most economically important traits of the breeding ewes. A genetic improvement by one genetic standard deviation (σ_a ) in these traits resulted in a profit of Ethiopian Birr 36.03-60.47/ewe/year. A fair correlation (r = 0.63) was observed between farmers' traits preference (conjoint-based choice card experiment) and the estimated economic value of traits indicating a good relationship between farmers' preferences for traits and economic values of the traits. This would indicate that weighting traits in selection indexes with farmers' trait selection using a conjoint-based choice experiment would direct genetic improvement towards desired profitability. Moreover, the fair correspondence between the two methods suggests that bio-economic modelling, if designed properly considering farmers' concerns, could be used to reflect farmers' breeding objectives. Therefore, for reasonable genetic progress and sheep flock profitability, more attention should be given to litter size, preweaning lamb survival and body weight at 6 months of age as they are preferred by farmers and their economic weights. Further, research on the modalities for complementary use of the two methods to define breeding objectives under smallholder conditions is warranted.

Direct and indirect contributions of molecular genetics to farm animal welfare: a review

Since domestication, farm animals have played a key role to increase the prosperity of humankind, while animal welfare (AW) is debated even today. This paper aims to comprehensively review the contributions of developing molecular genetics to farm animal welfare (FAW) and to raise awareness among both scientists and farmers about AW. Welfare is a complex trait affected by genetic structure and environmental factors. Therefore, the best welfare status can be achieved not only to enhance environmental factors such as management and feeding practices, but also the genetic structure of animals must be improved. In this regard, advances in molecular genetics have made great contributions to improve the genetic structure of farm animals, which has increased AW. Today, by sequencing and/or molecular markers, genetic diseases may be detected and eliminated in local herds. Additionally, genes related to diseases or adaptations are investigated by molecular techniques, and the frequencies of desired genotypes are increased in farm animals to keep welfare at an optimized level. Furthermore, stress on animals can be reduced with DNA extraction from stool and feather samples which reduces physical contact between animals and veterinarians. Together with molecular genetics, advances in genome editing tools and biotechnology are promising to improve FAW in the future.

Breeding Strategies for Weather Resilience in Small Ruminants in Atlantic and Mediterranean Climates

Many efforts are being made to cope with negative consequences of climate change (CC) on livestock. Among them, selective breeding of resilient animals to CC is presented as an opportunity to maintain high levels of performance regardless of variation in weather. In the present work, we proposed a set of breeding strategies to improve weather resilience in dairy goats raised in north-western European Atlantic conditions and dairy sheep raised in Mediterranean conditions while improving production efficiency at the same time. Breeding strategies differed in the selection emphasis placed on resilience traits, ranging from 0 to 40% in the index. Simulations were carried out mimicking real breeding programs including: milk yield, length of productive life, age at first kidding and mastitis incidence in dairy goats and milk, fat and protein yields, and fertility for dairy sheep. Considering the particular climatic conditions in the two regions, the predicted future climate scenarios, and genetic correlations among breeding objectives, resilience was defined as stability to weather changes for dairy goats and as the ability to improve performance under heat stress for dairy sheep. A strategy giving a selection weight of 10 and 20% for goat and sheep resilience, respectively, resulted in the best overall genetic response in terms of both, production and resilience ability. Not considering resilience in breeding programs could lead to a major production loss in future climate scenarios, whereas putting too much emphasis on resilience would result in a limited progress in milk production.

Selection Criteria for Improving Fertility in Spanish Goat Breeds: Estimation of Genetic Parameters and Designing Selection Indices for Optimal Genetic Responses

The aim of this study was to estimate genetic parameters for several female fertility criteria and to choose the most suitable selection index in Spanish Florida and Payoya goat breeds. In this study, we analyzed as fertility traits, the age at first kidding (AgFiKid), and the interval between the first and second kiddings (Int12Kid), between the second, third, and remaining kiddings (Int3toKid), and between all kiddings (IntAllKid) in 51,123 and 22,049 Florida and Payoya females, respectively. Genetic parameters were estimated by fitting animal models using restricted maximum likelihood (REML) methodology. We proposed six selection indices to compare the genetic responses for all traits included, based on a new selection index theory. The heritability and repeatability estimates of the traits were low, as expected. The genetic correlations among fertility traits covered a wide range of values from 0.07 (AgFiKid-Int12Kid) to 0.71 (Int3toKid-IntAllKid) in Florida and from -0.02 (AgFiKid-Int12Kid) to 0.82 (Int3toKid-IntAllKid) in Payoya. Overall, the results of this study indicate that IntAllKid gives the highest genetic responses in both breeds but is expressed late in a female's life. However, AgFiKid and Int12Kid could be recommended as early selection criteria for female fertility in both breeds.

Does the Acknowledgement of αS1-Casein Genotype Affect the Estimation of Genetic Parameters and Prediction of Breeding Values for Milk Yield and Composition Quality-Related Traits in Murciano-Granadina?

Simple Summary

Genetic evaluations and the selection of breeding animals require the accurate estimation of genetic parameters for economically important traits. As a result, dairy livestock has evolved in response to the needs of producers and consumers. Genetic selection in goats has been mostly based on quantitative traits such as milk yield, fat, protein, and dry matter. However, as reported by the increased heritability values of these parameters after the inclusion of the different allelic variants of αS1 casein in evaluation models, the selection of animals carrying this gene could result in a more efficient genetic selection. High levels of genetic polymorphism (89.58% of polymorphic SNP—as only five out of the 48 SNPs assessed were monomorphic) that are related to greater production of coagulable proteins in milk, a fact that could be associated with a higher yield and improved curd firmness properties.

Abstract

A total of 2090 lactation records for 710 Murciano-Granadina goats were collected during the years 2005–2016 and analyzed to investigate the influence of the αS1-CN genotype on milk yield and components (protein, fat, and dry matter). Goats were genetically evaluated, including and excluding the αS1-CN genotype, in order to assess its repercussion on the efficiency of breeding models. Despite no significant differences being found for milk yield, fat and dry matter heritabilities, protein production heritability considerably increased after aS1-CN genotype was included in the breeding model (+0.23). Standard errors suggest that the consideration of genotype may improve the model’s efficiency, translating into more accurate genetic parameters and breeding values (PBV). Genetic correlations ranged from −0.15 to −0.01 between protein/dry matter and milk yield/protein and fat content, while phenotypic correlations were −0.02 for milk/protein and −0.01 for milk/fat or protein content. For males, the broadest range for reliability (R_AP) (0.45–0.71) was similar to that of females (0.37–0.86) when the genotype was included. PBV ranges broadened while the maximum remained similar (0.61–0.77) for males and females (0.62–0.81) when the genotype was excluded, respectively. Including the αS1-CN genotype can increase production efficiency, milk profitability, milk yield, fat, protein and dry matter contents in Murciano-Granadina dairy breeding programs.

Identification of breeding objectives for Begait goat in western Tigray, North Ethiopia

A sound breeding objective is the basis for genetic improvement in overall economic merit of farm animals. Begait goat is one of the identified breeds in Ethiopia, which is a multipurpose breed as it serves as source of cash income and source of food (meat and milk). Despite its importance, no formal breeding objectives exist for Begait goat. The objective of the present study was to identify breeding objectives for the breed through two approaches: using own-flock ranking experiment and developing deterministic bio-economic models as a preliminary step towards designing sustainable breeding programs for the breed. In the own-flock ranking experiment, a total of 45 households were visited at their homesteads and were asked to select, with reasons, the first best, second best, third best, and the most inferior does from their own flock. Age, previous reproduction, and production information of the identified animals were inquired; live body weight and some linear body measurements were taken. The bio-economic model included performance traits (weights, daily weight gain, kidding interval, litter size, milk yield, kid mortality, pregnancy, and replacement rates) and economic (revenue and costs) parameters. It was observed that there was close agreement between the farmers' ranking and bio-economic model results. In general, the results of the present study indicated that Begait goat owners could improve performance of their goats and profitability of their farms by selecting for 6-month weight, litter size, pre-weaning kid survival rate, and milk yield.

Determining the appropriate selection index for Rayeni Cashmere goat under pasture-based production system

The aim of the present study was to identify the significance of Rayeni Cashmere goat’s socioeconomic traits so as to derive economic weights for the selection criteria that can be used easily by goat breeders. A deterministic bio-economic model was used to estimate economic value for adult bodyweight of doe (BWD), annual milk yield (MW), annual cashmere weight (CW), bodyweight of kids sold at 6.5 months (WK), and number of kids sold at 6.5 months per doe (NK). The relative importance of traits was determined on the basis of the estimated economic values, and, consequently, the most beneficial traits were applied to construct selection indices. Five selection indices with different herd sizes and buck ratios were proposed (I1–I5). The traits included in each index were as follows: BWD, MW, CW, WK and NK (I1); MW, CW, WK and NK (I2); BWD, MW, WK and NK (I3); BWD, MW and CW (I4); and BWD, CW, WK and NK (I5). Absolute economic values (US$) of BWD, MW, CW, WK and NK traits were $–0.870, $0.111, $5.660, $21.655 and $1.712 respectively. The results indicated that in all indices, the genetic and economic gains were elevated by an increased herd size and a decreased buck ratio. The maximum values of genetic and economic gains were obtained in herd size of 400 and buck ratio of 0.04. The highest genetic gain was obtained under Index 1, while the highest amount of economic gain was acquired under Index 2; however, the maximum accuracy of selection index was achieved under Index 1. The obtained results revealed that the most appropriate selection index for this breed is Index 1, which includes BWD, MW, CW, WK and NK. By applying Index 1, we could concurrently promote improvement of all traits, which highlights the potential of this index as a good promising strategy for developing selection criteria of Rayeni Cashmere goat under a pasture-based production system.

Using the choice experiment method in the design of breeding goals in dairy sheep

Market failures are the main cause of poor acknowledgement of the true impact of functional sheep traits on the management and economic performance of farms, which results in their omission from the breeding goal or the estimation of non-representative economic weights in the breeding goal. Consequently, stated-preference non-market valuation techniques, which recently emerged to mitigate these problems, are necessary to estimate economic weights for functional traits. The purpose of this paper is to present an example of the use of a choice experiment (CE) in the estimation of economic weights for sheep traits for the design of breeding goals. Through a questionnaire survey the preferences of sheep farmers are recorded and their marginal willingness to pay (MWTP) for 10 production and functional traits is estimated. Data are analysed using random parameter logit models. The results reveal unobserved preference heterogeneity for fertility, adaptability to grazing and resistance to disease, thus highlighting that these traits are appreciated differently by farmers, because their needs are diverse. Positive MWTP is found for Greek breeds, high milk production and lambs with low fat deposition, for which there is high demand in Greek markets. On the other hand, MWTP for the cheese-making ability of milk is negative, stemming from the fact that sheep milk prices in Greece are not formulated according to milk composition. In addition, farmers seem to understand differences between udder shapes and attribute different values to various types. This application of the CE method indicates that communication channels among farmers and breeders should be established in order to enhance market performance and to provide orientation to the design of breeding programmes. Non-market valuation can be used complementarily to market valuation techniques, in order to provide accurate estimates for production and functional traits.

Bioeconomic model and selection indices in Aberdeen Angus cattle

A bioeconomic model was developed to calculate economic values for biological traits in full-cycle production systems and propose selection indices based on selection criteria used in the Brazilian Aberdeen Angus genetic breeding programme (PROMEBO). To assess the impact of changes in the performance of the traits on the profit of the production system, the initial values ​​of the traits were increased by 1%. The economic values for number of calves weaned (NCW) and slaughter weight (SW) were, respectively, R$ 6.65 and R$ 1.43/cow/year. The selection index at weaning showed a 44.77% emphasis on body weight, 14.24% for conformation, 30.36% for early maturing and 10.63% for muscle development. The eighteen-month index showed emphasis of 77.61% for body weight, 4.99% for conformation, 11.09% for early maturing, 6.10% for muscle development and 0.22% for scrotal circumference. NCW showed highest economic impact, and SW had important positive effect on the economics of the production system. The selection index proposed can be used by breeders and should contribute to greater profitability.