Unfavorable Genetic Correlations Research Articles

Deriving a preliminary breeding objective for commercial ostriches: an overview

Ostrich farmers rely on skins and meat as their most important sources of revenue, with feathers being of secondary importance. This paper provides a summary of parameter estimates (heritabilities and genetic correlations) estimated from the resource flock held at the Oudtshoorn Research Farm. Traits considered were egg production, chick production, mature liveweight, offspring slaughter weight and skin traits. Feather weight of mature breeding birds was not included, as revenue received for this commodity is comparatively low, and mostly reliant on quality. All the traits considered were moderately to highly heritable, and reproduction traits in particular were highly variable. No substantial unfavourable genetic correlations were noted, and worthwhile gains in all traits appear to be achievable within a selection objective based on economic principles. Economic weights for key traits were obtained from a bio-economical input–output simulation model that was prepared for the industry. A simple preliminary selection index including chick production (as a hen reproductive trait) and slaughter weight (as a measure of growth) appears to be adequate for the present needs, given the limited availability of routinely recorded traits. A key performance trait that is currently missing from the economic assessment is chick survival, which is known to be low and highly variable among ostrich flocks. Further information will be added as it becomes available.

Inheritance of density, microfibril angle, and modulus of elasticity in juvenile wood ofPinus radiataat two locations in Australia

A total of 1640 increment cores from 343 radiata pine ( Pinus radiata D. Don) families were sampled at two second-generation progeny trials, aged 6 and 7 years, for a detailed genetic study of juvenile wood quality traits. Density, microfibril angle (MFA), and modulus of elasticity (MOE) were determined from pith to bark using SilviScan®technology. Heritability was greatest for area-weighted density at the two sites (0.63 and 0.77, respectively), and the lowest for growth traits (<0.23). Genotype by environment interaction was low for all three wood quality traits. A positive genetic correlation between density and MOE (0.43), and a highly negative, and therefore, favourable genetic correlation between MFA and MOE (–0.92) were observed, implying that improvement of multiple juvenile wood properties is possible. The genetic correlations between whole-core wood quality traits and individual-ring measurements suggest that improvement for juvenile wood properties across the entire profile of the corewood including the innermost rings can be achieved. However, density, MFA, and MOE had unfavourable genetic correlations with diameter growth suggesting that selection for increased density and MOE, and reduced MFA in the absence of selection for growth will result in a genetic loss for growth rate.

Genetic analyses of piglet survival and individual birth weight on first generation data of a selection experiment for piglet survival under outdoor conditions

Peri- and postnatal mortality of piglets is reported to be around 20% and genetic improvement in piglet survival has great potential benefits in terms of animal welfare, economics and the environment. The indication of an unfavourable genetic correlation between litter size and survival in particular points to the importance of including piglet survival in those pig breeding programmes that currently only aim to increase litter size. Phenotypically, individual birth weight is closely associated with piglet survival (Roehe and Kalm, 2000). Genetic parameters for piglet survival traits and individual birth weight therefore need to be estimated in order to genetically improve piglet survival efficiency

Identification of Germplasm of Possible Value for Confronting an Unfavorable Inverse Genetic Correlation in Tobacco

To be commercially viable in the USA, a flue‐cured tobacco (Nicotiana tabacum L.) cultivar must be high‐yielding and also meet minimum requirements for percent total alkaloids (PTA). The negative correlation between yield and PTA complicates development of higher‐yielding cultivars with acceptable leaf chemistry, however. Identification and use of germplasm possessing alternative alleles positively affecting PTA could be an important component of strategies to develop commercially acceptable, higher‐yielding cultivars. Choice of donor germplasm should be done carefully, however, because yield modulates the phenotypic expression of PTA. Consequently, comparison of materials for genetic potential to accumulate alkaloids might best be done at common levels of yield. This investigation used manual control of leaf number to manipulate yield of fifteen diverse tobacco genotypes grown in a split‐plot design in two North Carolina environments. Within genotypes, the relationships between PTA and yield were found to be negative. Through statistical analyses, germplasm accessions TI 464 and TI 959 were found to exhibit the highest levels of PTA at given levels of yield in both environments. Data on N‐partitioning indicated that these genotypes may have increased genetic potential for utilizing accumulated N for alkaloid synthesis. Transfer of alleles from these genotypes to elite germplasm pools may facilitate development of higher‐yielding cultivars with acceptable PTA levels.

Feasibility of a Linear Scoring Method of Udder Morphology for the Selection Scheme of Sardinian Sheep

Breeders are increasingly interested in improving the machine milkability of Sardinian dairy sheep by selection for udder morphology. Nine-point linear scales were developed to appraise teat placement, degree of suspension of the udder, udder depth, and degree of separation of the 2 halves. Repeatabilities within and across lactation were estimated on an experimental flock. Ewes were scored at least 3 times a year from 1999 to 2003. Within-lactation repeatabilities were greater than 0.70 for all linear traits, whereas across-lactation repeatabilities ranged from 0.59 to 0.66. The first linear combination of basic traits, obtained by principal component analysis, was highly correlated with teat placement, degree of suspension of the udder, and udder depth and showed an across-lactation repeatability of 0.76. These results indicate that an accurate evaluation of animals is possible by a single, early lifetime score. Genetic parameters of linear udder traits were estimated using a REML method applied to a sire model. Data were selected from 76,984 scores of Sardinian yearling ewes collected by 31 classifiers from 1999 to 2004. Two models were compared, one fitting the contemporary group effect as fixed and the other as random. Heritabilities of udder traits ranged from 0.19 to 0.31. The model with the random contemporary group effect produced slightly higher heritabilities and higher correlations between the sires’ estimated breeding values and the daughters’ average scores. As a whole, the genetic correlations between udder traits were favorable, indicating that selection for one trait will produce a positive evolution of the overall udder conformation. In particular, the degree of suspension of the udder was highly correlated with udder depth (0.82). Genetic correlations with milk yield were unfavorable but generally low, with the exception of udder depth (−0.48). Genetic trends were estimated using an animal model. Only udder depth showed a negative constant genetic trend. Overall results indicated that genetic improvement of the udder morphology of Sardinian ewes is feasible, with major emphasis on teat placement and degree of udder suspension, traits showing the highest heritabilities and low unfavorable genetic correlations with milk yield.

Selection response in fecal worm egg counts in the Rylington Merino parasite resistant flock

The Rylington Merino internal parasite resistant selection line was initiated in 1987 from a wide genetic base of 100 ewe flocks. Selection for parasite resistance was based on selecting animals with a low worm egg count in a natural parasite challenge environment. The realised annual genetic gain for estimated breeding value of worm egg count is 2.7%. The genetic gain in parasite resistance has been achieved without any adverse genetic correlations with the other economically important production traits. There is an unfavourable genetic correlation between worm egg count and scouring traits. The recommendation to industry is to select for both low worm egg count and reduced diarrhoea and combine these traits with other economically important production traits. The relative weighting applied to each component trait will vary according to the local parasite challenge situation and the time frame available to achieve sustainable parasite control.

Growth rate of growing pigs is weakly correlated genetically with litter size, while the amount of genetic variation for growth rate changes with litter size

We reasoned that if we assessed pigs for litter size and growth rate during the grow-out stage of production (25–100 kg body weight) we would find: 1) an unfavourable genetic correlation between litter size and growth rate; and 2) that the amount of additive genetic variation expressed for growth rate varies with litter size. We tested these premises by assessing 2212 litters from the Yorkshire breed for litter size, while 3038 growing pigs from 550 of these litters were assessed for growth rate during the grow-out stage of production. Genetic correlations were estimated using the additive genetic (co)variances obtained from a bivariate linear animal model fitted to litter size and growth rate. The amount of additive genetic variation expressed for growth rate as a function of litter size was estimated by fitting a univariate linear animal model with random regression on litter size. Our findings did not support the first of our premises as we found that the genetic correlation between litter size and growth rate was favourable (0.28±0.27), albeit not significantly different from zero. However, we were able to support our second premise as we found that the relationship between amount of additive genetic variation for growth rate and litter size was quadratic; the amount of additive genetic variation was highest in small and large litters (h2=0.60 and 0.65), and lowest in intermediate litter sizes (h2=0.29). These findings indicate that: 1) breeding for litter size would not reduce the growth rate of growing pigs; and 2) the amount of genetic variation for growth rate changes with litter size.

Genetic parameters for osteochondrosis traits in elbow joints of crossbred pigs and relationships with production traits

AbstractA total of 9360 offspring of 12 purebred Duroc sires and 692 Landrace × Yorkshire sows were evaluated for six osteochondrosis traits in the left elbow joints at slaughter. Osteochondrosis traits, growth pre- and post weaning, and meat content at slaughter were analysed simultaneously by a multivariate genetic model. Castrates scored worse than female pigs for nearly all osteochondral traits. Heritability of elbow osteochondrosis was moderate (0·02 to 0·28) and, thus, selection against the disorder is possible. Phenotypic correlations among joint surface abnormalities, cartilage thickness, subchondral lesions and cracks in the cartilage at the osteochondral junction in the medial condyle ranged from 0·33 to 0·69, whereas genetic correlations ranged from 0·75 to 0·97. Phenotypic correlations of the sagittal central groove with other abnormalities in the medial condyle were low and insignificant but genetic correlations were strongly significant (0·66 to 0·77). Depression of the proximal edge of the radius was to some extent phenotypically correlated to abnormalities in the medial humeral condyle (around 0·2), while genetic correlations ranged from 0·05 to 0·52. Significant genetic correlations among osteochondral traits indicate that all are part of the osteochondrosis complex. Abnormalities in the joint surface showed the strongest genetic correlations with other osteochondrosis variables in the elbow joint and were moderately inherited (h2= 0·22), which indicates that this trait can be used as a marker to select against osteochondrosis. Osteochondral traits had no significant genetic correlations with growth to weaning and to 30 kg, slight negative (favourable) genetic correlations with growth from 30 to 100 kg, and slightly positive (unfavourable) genetic correlations with meat content in carcass.

Improving wood quality in the western gulf forest tree improvement program: the problem of multiple breeding objectives

Currently, both industrial and private landowners in the Western Gulf Forest Tree Improvement Program (WGFTIP) area are compensated for their timber primarily based on the weight or volume of green wood reaching the mill gate. This places an immediate economic focus on adaptability and volume growth. However, selection for volume growth alone could result in decreased wood quality over time. Wood quality characteristics including stem straightness, wood specific gravity, and microfibril angle have either neutral or slightly unfavorable genetic correlations with volume growth in the WGFTIP loblolly pine (Pinus taeda L.) program. Since most WGFTIP members also consider wood quality an important selection criterion, the WGFTIP must define the best possible set of selection criteria given that (1) no single set of breeding objectives can be considered optimal for multiple products and (2) improvement in wood quality has no readily recognized economic importance in the existing market. To meet this challenge, the WGFTIP has implemented different strategies for its mainline breeding and deployment populations. In the mainline population, consistent breeding and selection criteria are used across members, while in the various deployment populations, selections are tailored to meet the specific needs of each member. The WGFTIP is also developing an elite wood quality population (WQEPop) based on backward selection. For the WQEPop to be successful, the economic importance of improved wood quality must be recognized, and landowners must be compensated for growing higher quality timber, especially if this results in reduced volume production. Improved methodology for within-family selection and for wood quality trait measurement is also important.

The Relationship Between Fertility, Rump Angle, and Selected Type Information in Holstein-Friesian Cows

Some dairy cattle breeders believe that dairy cows with high pin bones will have poorer fertility. The aim of this study was to examine this claim by investigating the relationships, both genetic and phenotypic, between fertility, rump angle, and other selected type traits in first-lactation Holstein-Friesians. Results showed an unfavorable genetic correlation (−0.16) between calving interval and rump angle, suggesting that animals with high pin bones would have a longer calving interval. However, no significant genetic or phenotypic correlation between days to first service and nonreturn rate and rump angle was observed. No evidence of a relationship, linear or quadratic, between any fertility trait and rump angle was found. Udder support and mammary system were unfavorably correlated to calving interval (0.25 and 0.14, respectively), suggesting that cows with more functional udders would have a longer calving interval. Legs and feet score was favorably correlated to nonreturn rate, suggesting that animals with good legs and feet would be less likely to return to service.

Genetic (co)variation in resistance to White Spot Syndrome Virus (WSSV) and harvest weight in Penaeus ( Litopenaeus) vannamei

A total of 339 full-sib families (representing 143 paternal half-sib families) and 337 full-sib families (representing 145 paternal half-sib families) were respectively challenged with White Spot Syndrome Virus (WSSV) in a controlled environment and tested for growth performance under commercial growing conditions. The families were derived from two selected lines. The estimates of heritability ( h 2 ± SE) for the two lines were 0.03 ± 0.02 and 0.07 ± 0.02 for WSSV resistance and 0.21 ± 0.04 and 0.20 ± 0.04 for harvest weight. Moreover, there was an unfavorable genetic correlation of −0.55 and −0.64 in the two lines between resistance to WSSV measured in controlled challenge tests at an average weight of 3 g and growth performance to harvest size in ponds. Thus, for simultaneous improvement of both traits breeding values for WSSV resistance must be obtained from data recorded on sibs of the breeding candidates.

Direct and correlated responses to selection for high or low faecal nematode egg count in Perendale sheep

A selection experiment with Perendale sheep was established in 1986, with lines selected solely on the basis of high or low faecal nematode egg count (FEC) in lambs after weaning. Ranking for FEC involved a natural mixed‐species challenge in all years, although in early years this was augmented by an artificial challenge with Haemonchus contortus larvae. Faecal samples were taken from each animal for FEC on two occasions, separated by an anthelmintic drench. A total of 1840 lambs were recorded for FEC in the high and low selection lines from 1986 up to the 2002‐born lamb crop. Direct responses to divergent selection for or against FEC were estimated, along with indirect responses in live weights (lambs, yearlings, and adult mixed‐age ewes), in fleece weights (yearlings and ewes) and in breech soiling ("dag") scores. Analyses of both lines across all years were carried out using animal‐model restricted maximum likelihood techniques and also fixed‐effects models. The realised heritabilities of loge(FEC + 100) at the two sampling times were 0.22 ± 0.03 and 0.16 ± 0.03; the genetic correlation estimates between loge(FEC1 + 100) and yearling live weight and fleece weight were 0.36 ± 0.17 and 0.54 ± 0.16, respectively. Averaging the breeding value results for the 1998–2002 crops, the back‐transformed FEC means averaged 556 and 114 eggs/g for the high and low lines, respectively, representing a 4.9‐fold line difference. When exposed to equal parasite challenge, lambs from the high FEC line were heavier than low‐line lambs by 6–12% (breeding ewes 8%), with all differences being significant (P < 0.001); corresponding figures for fleece weight were 24–26% (breeding ewes 15%), again with all differences significant (P< 0.001), and dag scores averaged 0.55 units higher in low‐line animals (P < 0.001). It is concluded that, under natural mixed‐species parasite challenge on pasture, small rates of genetic change for FEC were achieved in small, closed populations of Perendales. There were unfavourable correlated responses to selection to reduce FEC, comprising lower weights, reduced fleece weights, and more dags. The prospect of index selection to break the unfavourable genetic correlations with FEC is discussed.

Heritabilities, Genetic Correlations, and Genetic Change for Female Fertility and Protein Yield in Norwegian Dairy Cattle

Data from 1,815,581 first insemination records from daughters of 2697 Norwegian Dairy Cattle (NRF) sires were analyzed. A multitrait model was used to estimate genetic parameters and genetic change for 56-d nonreturn rate in virgin heifers (NR56D0), for 56-d nonreturn rate in first lactation cows (NR56D1L), for interval from calving to first insemination (CFI1L), and for protein yield (PY3051L). The heritabilities for NR56D0, NR56D1L, CFI1L, and PY3051L were 1.08, 0.99, 3.01, and 20.80%, respectively. Genetic correlation between heifer and cow fertility was high and favorable between NR56D0 and NR56D1L (0.54) and moderate and unfavorable between NR56D0 and CFI1L (0.24). The genetic correlations between NR56D1L and CFI1L and between NR56D0 and PY3051L were 0.08 and 0.04, respectively. A small, unfavorable genetic correlation between NR56D1L and PY3051L (−0.18) was found, while the genetic correlation between PY3051L and CFI1L was strongly unfavorable (0.47). Since 1972, NRF sires have been selected for NR56D0 using breeding values estimated from large progeny groups and with considerable weight in the total merit index. A linear regression analysis of sire PTA on year of first insemination of daughters showed an annual genetic change of 0.14% units for NR56D0. Selection was able to stabilize the genetic change of NR56D1L (0.03%/yr) but an undesirable change for CFI1L (0.11 d/yr) was found. The change of sire PTA for PY3051L was 0.63 kg/yr.

A new approach to detect non-pleiotropic QTL for correlated traits

RiassuntoUn nuovo metodo per l’individuazione di QTL non-pleiotropici nel caso di caratteri correlati. L’approccio si basa sull’analisi dei fenotipi per un carattere d’interesse (A) ottenuti come residui della regressione lineare su un carattere positivamente correlato (B). Il lavoro dimostra, attraverso simulazioni e con un’applicazione a dati reali, che tale approccio aumenta la potenza di individuazione di QTL con solo effetto su A, in misura proporzionale alla correlazione tra caratteri. Esso comporta tuttavia il rischio di concludere erroneamente all’esistenza di QTL non-pleiotropici per A quando il locus influenza B. E’ possibile limitare tale rischio estendendo la ricerca di QTL al carattere correlato. In tal modo, l’effettiva probabilità di false identificazioni si riduce proporzionalmente al rischio di errore di prima specie scelto per B.

Genetic parameters among growth and carcass traits of Canadian Charolais cattle

Genetic parameters for three growth and five carcass traits were estimated for Charolais using a combination of carcass progeny test, purebred field performance and pedigree data. Heritabilities and genetic and residual correlations were derived from variance components for birth weight (BWT, n = 54 221), 205-d weaning weight (WT205, n = 31 384), postweaning gain (PWG, n = 19 403), hot carcass weight (HCW, n = 6958), average subcutaneous fat thickness (FAT, n = 6866), longissimus muscle area (REA, n = 6863), marbling score (MAR, n = 6903) and estimated carcass lean yield percentage (PLY, n = 6852) with an animal model (n = 78 728) and restricted maximum likelihood. Breed of dam and contemporary group appropriate to each trait were included as fixed effects in the model, whereas random effects included direct genetic for all traits, maternal genetic for BWT and WT205, and maternal permanent environmental for WT205. Carcass traits were adjusted to a constant harvest age of 425 d. Heritability estimates of 0.53, 0.22, and 0.21 were obtained for direct components of BWT, WT205, and PWG, respectively, and maternal heritabilities were 0.16 and 0.10 for BWT and WT205, respectively. Direct × maternal genetic correlations for BWT (-0.49) and WT205 (-0.35) were negative. Heritabilities for HCW, FAT, REA, MAR, and PLY were 0.33, 0.39, 0.43, 0.34, and 0.46, respectively. Genetic correlations among direct effects for growth traits were moderately positive and generally uncorrelated with maternal effects across traits. Lean and fat deposition in the carcass generally had negative, unfavorable genetic correlations, although improvement in lean yield and marbling score may not be strongly antagonistic. Genetic correlations of direct and maternal components of growth traits with carcass traits suggested that selection for increased growth rate would not be antagonistic to improvement in carcass yield or meat quality. Key words: Carcass, Charolais, correlation, genetic parameters, growth

Genetic parameters of fertility traits and their correlation with production, type, workability, liveweight, survival index, and cell count

First and second parity data on calving interval (CI, days), survival to next lactation (Surv, scored 1 or�0), calving to first service interval (CFS, days), 25-day first service non-return rate (FNRR, scored 1 or 0), and insemination or submission rate (InsemR, scored 1 or 0) of Holstein-Friesian cattle were analysed using a sire model to estimate genetic parameters. The estimated genetic parameters were used to obtain predicted transmitting ability (PTA) of sires for fertility traits and Surv, including 6-week pregnancy rate (6-w PR). PTA for 6-w PR was calculated based on an estimated heritability of 0.07 and genetic and environmental correlations with the other fertility traits and Surv. In addition, approximate genetic correlations of fertility traits and Surv with milk yield, type traits, workability (likability, milking speed, temperament), survival index (a measure of survival calculated from estimated breeding values on survival, likability, and type traits), bodyweight, and cell count were estimated. Heritability (h2) of fertility traits was 2–4% in the first parity and 1–2% in the second parity. Genetic correlations between fertility traits were generally higher in magnitude than environmental correlations, particularly in the first parity. The difference in PTA between the best and worst sires was high (21 days in CI and 21% in 6-w PR), showing the scope for selection. Approximate genetic correlations between fertility and most traits that are currently evaluated were low to moderate. Milk, protein and fat yield, body size, overall type, mammary system, udder texture, muzzle width, angularity, body depth, chest width, foot angle, and rear attachment width were unfavourably correlated (0.1–0.5) with most fertility traits. Fat and protein % were favourably correlated with both CI and 6-w PR (~0.2). Pin set was moderately favourably correlated (0.28) with 6-w PR. Surv was favourably (positively) correlated with temperament, likability, and survival index (~0.5). The wide variation in particular in CI and 6-w PR between bulls and the generally unfavourable approximate genetic correlations of fertility traits with most traits for which selection is currently practiced suggest that genetic evaluation for fertility should be introduced.

Genetic evaluation of fertility using direct and correlated traits.

Poor fertility has become a major reason for involuntary culling of dairy cows in the United Kingdom. Calving interval (CI) and body condition score (BCS) are recorded, heritable, genetically correlated with each other, and could be used to extend the scope of dairy indices to include fertility traits. The use of U.K. insemination information for the evaluation of fertility has not been examined previously. Fertility and correlated traits were examined using nationally recorded milk (MILK = daily milk yield at test nearest d 110), BSC, and fertility traits (CI and the insemination traits of nonreturn rate after 56 d, NR56; days to first service, DFS; and number of inseminations per conception, INS). Genetic parameters for the traits were estimated simultaneously with a multitrait sire maternal grandsire (MGS) model and a multitrait BLUP sire MGS model was used to predict sire predicted transmitting abilities for each trait. The relationship between the fertility traits and other predicted transmitting abilities calculated in the United Kingdom was then examined. Heritabilities for the fertility traits were CI = 0.033 +/- 0.01, DFS = 0.037 +/- 0.01, NR56 = 0.018 +/- 0.001, and INS = 0.020 +/- 0.001, with a genetic correlation of 0.671 +/- 0.063 between CI and DFS and -0.939 +/- 0.031 between NR56 and INS. There was an unfavorable genetic correlation between the fertility traits and milk yield and BCS. Predicted transmitting abilities produced are similar in size and range to those produced in other studies and genetic trends are as expected. Results to date are encouraging and suggest that the planned program of work will lead to a fertility index that, when used by breeding companies, will lead to improvements in national dairy cow fertility.

Genetic Parameters for Body Condition Score and its Relationship with Type and Production Traits in Swiss Holsteins

The objectives of this study were to estimate the genetic and environmental parameters between body condition score (BCS) and 27 conformation and 3 production traits in Swiss Holstein cattle. The dataset consisted of 31,500 first-lactation cows, which were daughters of 545 sires in 1867 herds. Bivariate sire models with relationships among sires were used to estimate parameters. Least squares means for BCS by lactation stage show that cows lose BCS up to 5 mo after calving and gain BCS prior to the next calving. Regression models showed that an increase in age and percentage of Holstein genes results in an increase and decrease in BCS, respectively. Heritability (h2) was 0.24 for BCS score, which indicates good potential for selection. Sire estimated breeding values for BCS ranged from −0.46 to +0.51 units. Heritabilities ranged from 0.08 (heel depth) to 0.46 (rump width) for type traits and 0.23 to 0.29 for yield traits. Genetic correlations of BCS with 8 conformation traits were significant; stature (0.28), heart girth (0.21), strength (0.17), loin (−0.39), body capacity (0.19), dairy character (−0.35), udder quality (−0.42), and teat position rear (−0.33). Milk production and body condition have an unfavorable genetic correlation (−0.12 to −0.17). These results show that selection for good body condition, body conformation, and optimal milk production is possible and their genetic associations reported here will be useful for designing Swiss breeding goals.

Experiences of including reproduction and health traits in Scandinavian dairy cattle breeding programmes

Reproduction and health traits are of significant economic importance for dairy production. Most of these traits are expressed in a categorical way and show heritabilities of 5% or less. Nevertheless, their additive genetic variation is considerable. For example, the incidence of clinical mastitis in the first lactation varies among daughter groups of Swedish Holstein bulls between 10 and 26%, stillbirth rate at first parity between 3 and 16%, and the number of inseminations per serviced cow between 1.6 and 1.9. Unfavourable genetic correlations of the order of 0.2–0.4 between production on one side, and mastitis and female fertility on the other, have generally been found. Well integrated recording schemes in the Scandinavian countries enabled early the adoption of total merit indexes (TMI), including reproduction and health traits, into their selection schemes. In practice, TMI selection has proven to be effective in maintaining functional efficiency of the cows simultaneously with a sharp increase in production. As bull selection nowadays takes place globally, sustainable breeding programmes require more extensive recording and genetic evaluations of reproduction and health traits internationally, a development that presently grows quickly. The Scandinavian experiences are reviewed in this paper in the light of this international development.

Genetic and nongenetic factors influencing mohair production traits within the national selection scheme of Angora goats in France

The angora breeding of goat began in France about 1980. Today, about 7500 animals from 180 different farms, produce annually 30 t of mohair. The mohair from the entire French production is collected, graded and processed under the control of farmer’s cooperatives, then marketed directly to consumers as finished products, under a common trademark Le Mohair des Fermes de France. A national selection scheme was developed with breeders in order to improve both quality and quantity of mohair produced by Angora goats. This selection scheme is based on a performance recording system, a national genetic database and since 1998 a central testing station for bucks raised under a common standardised environment. The mean production data and the effects of some nongenetic factors (sex and age of animals, physiological status of females: nursing or not, year and breeding) on the production of mohair are described. Heritability estimates of the main fleece traits are moderate to high and vary between 0.19 and 0.53. The weight and the homogeneity of the fleece are in unfavourable genetic correlation with mean fibre diameter (0.37 and −0.59, respectively), but favourable with the kemp score (0.57 and −0.50, respectively). These results are taken into account to consider the breeding value of animals and improve the efficiency of the genetic improvement programme of Angora goats in France.