Vergelijking tussen Holsteins en kruisingen op melkveeproefbedrijf De Marke in de periode 2014-2019 : Met welke genetica of welk fokdoel op weg naar kringlooplandbouw?

A move towards a circular farming system affects the diet of dairy cows. At De Marke manure and minerals are used as efficiently as possible in order to reduce the amount of raw materials and energy needed for production to reduce the ecological footprint of the farm. In a circular system, the amount of available concentrates is constrained. Therefore, the question is if breeding for efficiency in a circular system means that we need to accomodate the breeding goals of dairy cows towards cows that produce more from a given low quality diet and are able to cope with increased variability of the quality of the available diet. A tailored breeding approach is an essential building block, to ensure cows’ health, welfare and production in new farming systems related to resource availability. In this study, we compared the performance of two genetic lines of cows on this dairy farm. The crossbreeding scheme was introduced in 2011 after a period where the performance of the cattle at De Marke appeared to be lower than expected. Out of the ninety dairy cows at “De Marke”, half is inseminated with Holstein semen, while the other half was used to set up a three-way rotation cross scheme (Holstein, Montbéliarde, and Swedish Red cattle). Each generation bulls of the three breeds are used in a specific order and the resulting crossbred females in all generations can be used to produce replacements. All cattle are managed equally. The research questions concern the performance in this system on the characteristics: production, reproduction, health and longevity: • For the farm De Marke compared with the Dutch average performance • For the comparison of the selection lines on De Marke (Holstein (HF) with three-way rotation cross (X)) For the period 2014-2019, 446 lactations of 187 cows up to lactation number 5 were analysed in order to be able to make an correct comparison in the performance of animals. These are purebred animals, two way crosses and the younger animals are from three way crosses. The time span of this research is too limited to answer question about the longevity of the cows. The analyses show that in the farming system on De Marke (aimed at low losses and emissions), a level of milk production can be achieved that is comparable to the national black-and-white dairy cattle trend, whereas the contents of fat and protein are above average. The averages for reproduction characteristics compare favorably with the national averages. Both lines of cattle perform well within this extensive farming system. Differences in production and reproduction traits between the two breeding lines became smaller over the years. In recent years, the variation in traits for the available Holstein bulls greatly increased, this was helpful to improve longevity and fertility traits. The analysis highlights the importance of a large pool of genetic variation within and between cattle breeds. This variation will be essential for breeding programs when cows have to perform in a different environment, as will be the case when transitioning towards circular dairy farming. The comparison of the different traits show that the performance follows the breeding values. That means that for Holstein it was more easy to focus on milk production and for the three-way rotation cross to focus on fertility. The advice is to pay attention to this and select only bulls which are for all traits good enough. Breeding values can help in this. Crossbreeding is one of the ways to breed healthy cattle, but there are more ways to the future