J. Juga

Economic values of production and functional traits, including residual feed intake, in Finnish milk production

Improving the feed efficiency of dairy cattle has a substantial effect on the economic efficiency and on the reduction of harmful environmental effects of dairy production through lower feeding costs and emissions from dairy farming. To assess the economic importance of feed efficiency in the breeding goal for dairy cattle, the economic values for the current breeding goal traits and the additional feed efficiency traits for Finnish Ayrshire cattle under production circumstances in 2011 were determined. The derivation of economic values was based on a bioeconomic model in which the profit of the production system was calculated, using the generated steady state herd structure. Considering beef production from dairy farms, 2 marketing strategies for surplus calves were investigated: (A) surplus calves were sold at a young age and (B) surplus calves were fattened on dairy farms. Both marketing strategies were unprofitable when subsidies were not included in the revenues. When subsidies were taken into account, a positive profitability was observed in both marketing strategies. The marginal economic values for residual feed intake (RFI) of breeding heifers and cows were -25.5 and -55.8 €/kg of dry matter per day per cow and year, respectively. The marginal economic value for RFI of animals in fattening was -29.5 €/kg of dry matter per day per cow and year. To compare the economic importance among traits, the standardized economic weight of each trait was calculated as the product of the marginal economic value and the genetic standard deviation; the standardized economic weight expressed as a percentage of the sum of all standardized economic weights was called relative economic weight. When not accounting for subsidies, the highest relative economic weight was found for 305-d milk yield (34% in strategy A and 29% in strategy B), which was followed by protein percentage (13% in strategy A and 11% in strategy B). The third most important traits were calving interval (9%) and mature weight of cows (11%) in strategy A and B, respectively. The sums of the relative economic weights over categories for RFI were 6 and 7% in strategy A and B, respectively. Under production conditions in 2011, the relative economic weights for the studied feed efficiency traits were low. However, it is possible that the relative importance of feed efficiency traits in the breeding goal will increase in the future due to increasing requirements to mitigate the environmental impact of milk production.

Genetic parameters for hoof disorders and feet and leg conformation traits in Finnish Holstein cows

Hoof disorders are a major welfare problem in dairy farming and result in considerable costs to the farms. In this study, the data from 24,685 Holstein cows from 1,337 herds between 2003 and 2010 were used to evaluate the correlation between hoof disorders and feet and leg conformation traits using a binomial mixed model for hoof disorders in Finnish Holstein cows. Heritabilities and correlations among the hoof disorders and feet and leg conformation traits were also estimated. Heritability estimates from univariate logistic models for 8 hoof disorders ranged from 0.02 (sole hemorrhage, chronic laminitis, and heel horn erosion) to 0.13 (digital dermatitis). Heritability estimates using the liability scale from the multivariate linear model for the 5 most-common hoof disorders ranged from 0.02 (sole hemorrhage) to 0.11 (corkscrew hoof). Estimates of heritability for feet and leg conformation traits from the multivariate linear model ranged from 0.10 (rear leg rear view) to 0.19 (rear leg side view). Genetic correlations among hoof disorders ranged from -0.36 to 0.57, and genetic correlations among feet and leg conformation traits ranged from -0.30 to 0.83. The genetic correlations between hoof disorders and feet and leg conformation traits ranged from -0.51 to 0.45. Most of the genetic correlations between various hoof disorders and feet and leg conformation traits were low and most were nonsignificantly different from zero. This indicates that indirect selection for better hoof health using feet and leg conformation traits as indicator traits is not efficient in the Finnish Holstein breed.

Selection against Mastitis and Cell Count in Dairy Cattle Breeding Programs

Abstract Different selection strategies were studied to improve milk traits and to reduce the frequency of clinical mastitis and somatic cell count. The results indicate that it is better to use both clinical mastitis and somatic cell count in the selection index to improve the resistance of animals to mastitis and to improve the quality of milk. Selection for protein yield simultaneously with selection against mastitis or somatic cell count would result in increased milk, fat and protein yields, increased protein content, decreased fat content and decreased frequency of clinical mastitis and somatic cell count. Maximizing the total net economic profit based on the current pricing system in Finland would not decrease somatic cell count or frequency of clinical mastitis.

Cumulative selection differentials and realized heritabilities

Two alternative ways of estimating cumulative selection differentials are compared. An alternative method is developed that includes the advantages of both methods. This alternative method is shown to give rise to less biased estimates of realized heritability

Estimation of Variance Components in Populations Selected over Multiple Generations

Abstract Methods for estimating variance components in selected data were compared using simulated data from a selection experiment. After five generations REML-method using full relationship matrix and recursive prediction which take account for decreased additive variance due to selection gave unbiased estimates. REML-estimates had smallest variance, but the difference between the variance of REML and recursive prediction estimates was small. Realized heritability estimates were biased downwards and their variance was considerably larger. The design of the experiment had a clear effect on the variance of the estimates. The bias and the variance of the estimates increased when family selection was used instead of mass selection.

Effect of replacement rate, crossbreeding and sexed semen on the efficiency of beef production from dairy herds in Finland

Abstract In Finland, during the past 10 years, the number of dairy cows has declined considerably leading to decreased domestic beef production which is partly compensated by increased suckler beef production. However, production of meat originating from dairy herds has been shown to be economically more profitable and to produce less greenhouse gas emissions per unit of product than beef production from suckler cow systems. Therefore, when safeguarding beef self-sufficiency, the intensification of beef production from dairy herds is a more promising option to consider. In this study, the possibility of different options for increasing dairy beef production was assessed by using a deterministic simulation. Increasing the use of crossbreeding in dairy herds, especially when combined with the use of Y-sorted semen, appeared to be the most efficient strategy for increasing dairy beef production. The decrease in the replacement rate increased beef production through the potential for enhancing crossbreeding.

A derivative-free algorithm to estimate bivariate (co)variance components using canonical transformations and estimated rotations

Abstract The use of derivative-free methods to give maximum likelihood estimates of bivariate (co)variance parameters is illustrated. An algorithm is given to estimate the four variance and two covariance parameters of two random effects associated with each trait when both traits are measured on all animals and the same fixed and random model hold for both traits. By reparameterising in terms of canonical heritabilities and a transformation matrix, a six-dimensional problem is reduced to a two-dimensional problem. It is shown how to derive the estimate of the transformation matrix given the values for the canonical heritabilities. Maximization is then only over the two dimensions of canonical heritabilities and the transformation matrix. The use and the properties of the method are illustrated with examples from simulated selection experiment data.

JOINT GENETIC EVALUATION OF BLACK-AND-WHITE DAIRY BULLS IN THE NORDIC COUNTRIES FOR DAIRY PRODUCTION TRAITS

Abstract Genetic ties between the Black-and-White dairy bull populations of Denmark, Finland and Sweden were investigated using pedigree records. Although direct ties were weak, substantial linkage existed via common exporting countries, namely Canada, Germany, the Netherlands and the USA. A joint evaluation of bulls progeny-tested in these three Nordic countries was feasible in the presence of data from the four exporting countries. National proofs of more than 35 000 bulls from these countries were then analyzed with a linear model to rank bulls across country for milk, fat and protein yields. Results from the international evaluation were consistent with results from individual national evaluations. National proofs of bulls whose semen had been imported into the Nordic countries were found biased upwards by an average 4–5%, resulting in a substantial over-estimation of the international proofs of foreign bulls. Excluding these records from the analysis did not affect the data connectedness. Joint Nordi...