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The aim of this paper is to identify differences in genetic variation of fatty acid (FA) composition in milk in different breeds. Data used included Meuse-Rhine-Yssel (MRY) and Holstein Friesian (HF) cattle breeds which were raised in the Netherlands. Both populations participated in the same milk recording system, but differed in selection history, where in the MRY there has been relatively very little emphasis on selection for high-input high-output production systems compared to HF. Differences in genetic variation were investigated by estimating breed specific additive genetic variances and heritabilities for FA contents in milk of MRY and HF. Mid Infrared Spectrometry spectra were used to predict total fat percentage and detailed FA contents in milk (14 individual FA and 14 groups of FA in g of fat/dL of milk). The dataset for MRY contained 2916 records from 2049 registered cows having at least 50% genes of MRY origin and the dataset used for HF contained 155,319 records from 96,315 registered cows having at least 50% genes of HF origin. Variance components of individual FA content in milk for the different breeds were estimated using a single trait animal model. Additive genetic variances for FA produced through de novo synthesis (short chain FA, C12:0, C14:0, and partly C16:0), C14:1 c- 9 and C16:1 c- 9 were significantly higher ( P <0.001) for HF compared to MRY. Heritabilities of the individual FA, C4:0 to C18:0, for HF ranged from 0.28 to 0.52 and for MRY from 0.17 to 0.34. Heritabilities of the individual C18 unsaturated FA for HF ranged from 0.11 to 0.34 and for MRY from 0.10 to 0.26. Although the mean content in milk for the FA C18:2 c- 9, t- 11 was low in both breeds, the additive genetic variance in our dataset was significantly higher for MRY ( P <0.05) compared to HF. Heritabilities of the groups of FA for HF ranged from 0.19 to 0.53 and for MRY from 0.11 to 0.28. For the majority of the FA, the additive genetic variances for HF were significantly higher compared to MRY, except for most of the poly-unsaturated FA. The results for the poly-unsaturated FA, however, may be affected by the lower accuracy of the predictions for these FA. In conclusion, our results show that the HF breed has substantially larger genetic variance for most FA compared to MRY. [ABSTRACT FROM AUTHOR]

Abstract: The important role of values is very evident when it comes to citizens'' concept of sustainability. The present paper had the objective to define sustainability as a socio-cultural concept for livestock production systems. The main research question was: how do Dutch citizens value various aspects of dairy production systems? We conducted farm visits with citizens panels in The Netherlands. We asked citizens about their on-farm perception (smelling, hearing, seeing and feeling) and what they perceived valuable to preserve for the future. We presented sustainability as a socio-cultural concept which included citizens'' valuable aspects (SCA) and concerns (SCI). We defined a socio-cultural aspect (SCA) as an aspect of a livestock production system which is mentioned by society as being valuable to preserve for the future. We identified an SCA as a socio-cultural issue (SCI) when it evokes societal concern in present time or is expected to do so in the future. By qualitative analysis we identified SCAs and SCIs of dairy production systems and combined these into socio-cultural themes (SCT). We found ten socio-cultural themes which contained 42 socio-cultural aspects (SCA), of which 27 were identified as socio-cultural issues (SCI). We can conclude that that livestock production systems have more values for society than solely food production, because only one of the ten identified socio-cultural themes directly concerned food production (SCT 1), whereas the nine other themes concerned values that go beyond food production: farming activities (SCT 2), farm income (SCT 3), animals (SCT 4), landscape (SCT 5), nature (SCT 6), environment (SCT 7), farming culture (SCT 8), national culture (SCT 9) and services for society (SCT 10). One of the main values of agriculture seems the combination of apparently contradicting aspects such as technology and nature within one system. In conclusion, sustainability as a socio-cultural concept for livestock production systems is defined by a wide range of socio-cultural aspects and issues, reflecting citizens'' values and concerns of that system and for a sustainable agriculture it is important that both SCIs and SCAs are taken into account. [Copyright &y& Elsevier]

Abstract: This paper aims to describe the changes prompted by conversion to organic farming for milk production and fertility of first parity Holstein cows. Data was collected for Dutch organic farms, with a distinction made between long-standing-organic farms, converted organic farms and a reference group of conventional farms. The percentage Holstein blood in the herds, milk production (kg milk, % milk fat, % milk protein), somatic cell scores (SCS), calving interval (CI) and age at first calving (AFC) were described over time. An animal model was used to estimate the effects of conversion on different traits based on data from converted organic farms. Milk production was lower and somatic cell counts were higher on long-standing-organic farms than on conventional and converted organic farms. Interestingly, at pre-organic farms, i.e. before their conversion, the milk production level was already lower than at conventional farms. The estimates from our statistical analysis showed a highly significant decrease in milk yield and protein percentage due to conversion. Also fat content decreased, SCS increased and AFC increased significantly. It can be concluded that the conversion to organic farming is a gradual process over years. Dutch farmers who decided during the late 1990s to convert to organic farming, represented a specific group of farmers distinct from conventional farmers, which was reflected by lower milk yields, milk fat percentage and protein percentage before conversion as compared to conventional farms. During conversion, significant changes in milk production, protein and fat contents and somatic cell scores took place. Age of first calving is an important difference between organic and conventional farming. [Copyright &y& Elsevier]