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In the double-muscled (DM) Belgian Blue beef (BBB) breed, caesarean section (CS) is being applied systematically as a management tool to prevent dystocia. As a matter of fact, CS is the only possible way of calving in the breed. High birth weight and a relatively small pelvic area are the main causes of dystocia and, in the DM-BBB breed, the reasons for the systematically applied CS. Selection for lower birth weight and larger pelvic sizes might reduce dystocia and routine CS. Few data on inner pelvic sizes of pedigree animals are available. Using external measurements to estimate the inner pelvic sizes might be an option to resolve this problem. In this study, animals of the DM-BBB breed were measured and weighed on farms and in abattoirs. External and internal pelvic sizes increased with live weight and age of the animals. Gender had a significant influence on inner pelvic traits. Increased muscular conformation was associated with decreased inner pelvic dimensions. Models with weight, gender, age, withers height and outer pelvic width (TcTc) can be used to estimate inner pelvic sizes (R-2 between 0.35 and 0.77). The estimated inner pelvic sizes can then be used to genetically evaluate pelvic traits in the DM-BBB breed. Improving weight, withers height and TcTc width in combination with lowering muscular conformation may help to decrease the high rate of caesarean section in the DM-BBB.

In dit rapport worden de resultaten beschreven van eenonderzoek naar de visie op fokkerij binnen de biologische landbouw in Nederland. Het doel van dit onderzoek was om, door middel van interviews en discussies met biologische veehouders en maatschappelijke organisaties, te komen tot een duidelijke visie op de fokkerij in de biologische landbouw.

Door introductie van de melkrobot verandert de leefomgeving van de veestapel. Een denkbaar gevolg is dat dochters van bepaalde stieren beter tot hun recht zullen komen op robotbedrijven dan op niet-robotbedrijven. In een studie is onderzocht of er rangordeverschillen ontstaan in fokwaarde tussen stieren voor melk-, vet- en eiwitproductie als gevolg van een verschil in melksysteem

Sexual differences in herding behaviour of African buffalo (Syncerus caffer) were studied by analysing at the herd level mitochondrial D-loop hypervariable region I and fourteen autosomal microsatellites. Three herds from Arusha National Park in Tanzania were analysed with mtDNA and five herds from Kruger National Park in South Africa with mtDNA and microsatellites. Significant mtDNA differentiation was observed among herds in Arusha NP (F-ST = 0.12, based on haplotype frequencies). Assignment tests with microsatellite data from Kruger NP showed that most frequent migration between herds is by males greater than or equal totwo years. This was confirmed by tests for herd differentiation and analyses with Lynch and Ritland's relatedness estimator. Within a herd, males younger than two years and females showed a higher relationship through a common father rather than a common mother, indicating that female herd members mate with only a few dominant males. This in turn suggests a female: male sex ratio larger than 5:1. The migration rate per generation between herds was estimated to be 5-20% for females and close to 100% for males. Finally, the implications for the management of buffalo populations are being discussed.

Pork producers in Western Europe more and more encounter a variety of societal concerns about pork and pork production. So far, however, producers predominantly focused on low consumer prices, therewith addressing just one concern. This resulted in an intensive and large-scale production system, decreasingly related to the area of farm land, and accompanied with increasing concerns about safety and healthiness of pork, animal welfare, environmental pollution, and others. An overview was given of possible concerns about West-European pork production with the consumers, citizens, and producers, and those concerns are traced back to the pork production system. The various kinds and qualities of information about the pork production system on which possible concerns are based have been worked out extensively in this paper. Knowledge about the aspects of pork production that can give rise to concerns can be used in two ways. First, the communication about those aspects towards consumers and citizens can be adjusted or extended to give them better possibilities to make food choices or to develop their own opinions about pork production. Second, producers could change the pork production system such that it better satisfies consumers and citizens. Such adaptations are well possible, as three pork quality schemes, which have been evaluated, illustrate. However, most of these adaptations can only be carried out at the cost of the present low consumer prices and will not occur spontaneously on a large scale. Therefore, accounting for the type and relevance of the concerns, legislation is necessary to address societal concerns in a balanced way such that pork production systems become acceptable for the majority of our society.

Om het aantal mastitisgevallen d.m.v. fokkerij te reduceren hanteert NRS sinds een aantal jaren een uiergezondheidsindex. Die wordt berekend aan de hand van mastitisvoorspellende kenmerken. Inmiddels is nieuwe informatie beschikbaar, waarmee genetische correlaties zijn berekend en waarmee het mogelijk werd de huidige berekening van de fokwaarde uiergezondheid tegen het licht te houden

In een Wagenings onderzoek, waarin de melksnelheid is bestudeerd, is een model gemaakt, waarbij het melkproces in de melkstal stap voor stap wordt doorlopen. Voor de verschillende fasen van het melkgiftpatroon per koe en de andere handelingen van de melker werden aannames gemaakt

Uitleg van de uitgangspunten van een computerprogramma dat de gemiddelde verwantschap bij de keuze van generatievaders en -moeders in de gaten houdt en de toename van de gemiddelde verwantschap probeert tegen te gaan

After a general introduction into the available breeding techniques for animal breeding and an overview of the organic principles, points for discussion are identified and scenario's for organically accepted breeding methods are discussed. Na een algemene inleiding over de verschillende beschikbare methoden voor het fokken van dieren en de ontwikkelingen in de biologische landbouw worden de discussiepunten besproken en een aantal scenario's geïdentificeerd voor de ontwikkeling vaneen biologisch geaccepteerde vorm van fokkerij.

In de eerste ervaringen van een Wagenings onderzoek werden melkveehouders op basis van de wijze van bedrijfsvoering met betrekking tot de afvoer in 5 bedrijfsstijlen ingedeeld: groeiboeren, ruige boeren, exportboeren, duurzame boeren en voorzichtige boeren

Estimates of heritabilities and genetic correlations for calving ease over parities were obtained for the Italian Piedmontese population using animal models. Field data were calving records of 50,721 first- and 44,148 second-parity females and 142,869 records of 38,213 cows of second or later parity. Calving ability was scored in five categories and analyzed using either a univariate or a bivariate linear model, treating performance over parities as different traits. The bivariate model was used to investigate the genetic relationship between first- and second- or between first- and third-parity calving ability. All models included direct and maternal genetic effects, which were assumed to be mutually correlated. (Co)variance components were estimated using restricted maximum likelihood procedures. In the univariate analyses, the heritability for direct effects was .19 /- .01, .10 /- .01, and .08 /- .004 for first, second, and second and later parities, respectively. The heritability for maternal effects was .09 /- .01, .11 /- .01, and .05 /- .01, respectively. All genetic correlations between direct and maternal effects were negative, ranging from -.55 to -.43. Approximated standard errors of genetic correlations between direct and maternal effects ranged from .041 to .062. For multiparous cows, the fraction of total variance due to the permanent environment was greater than the maternal heritability. With bivariate models, direct heritability for first parity was smaller than the corresponding univariate estimate, ranging from .18 to .14. Maternal heritabilities were slightly higher than the corresponding univariate estimates. Genetic correlation between first and second parity was .998 /- .00 for direct effects and .913 /- .01 for maternal effects. When the bivariate model analyzed first- and third-parity calving ability, genetic correlation was .907 /- .02 for direct effects and .979 /- .01 for maternal effects. Residual correlations were low in all bivariate analyses, ranging from .13 for analysis of first and second parity to .07 for analysis of first and third parity. In conclusion, estimates of genetic correlations for calving ease in different parities obtained in this study were very high, but variance components and heritabilities were clearly heterogeneous over parities

3 Wageningse onderzoekers onderzochten de prestaties van 5.000 koeien die in principe de kans hadden om 3 lactaties vol te maken. Met name is gekeken is naar de persistentie van de melkgift in de afzonderlijke lactaties en naar de erfelijkheidsgraad van de persistentie

The commercially grown broiler usually is a crossbred from specialized purebred sire and dam lines. The position of a purebred line in the crossbreeding system influences its genetic contribution to expression of productive and reproductive performance at different stages of the production column and, thus, influences the breeding goal for a given line. In broiler breeding, cumulative discounted expressions (CDE) should be considered to define breeding goals for multitrait selection. In the present study, a systematic design for the application of discounted gene flow methodology to derive CDE for production and reproduction traits in broiler breeding was developed. Factors considered as influencing the magnitude of CDE were: crossbreeding system (two-way, three-way, and four-way cross), selection scheme (with and without progeny testing and intensity of selection), selection path, trait (production at commercial stage and reproduction at either nucleus or multiplier stage), interest rate, and time horizon for evaluation. Performance data from a commercial breeding stock were applied in the analysis. Results indicated that levels of CDE were significantly affected by all factors studied. The more that pure lines were included in the crossbreeding system, the lower the CDE for a particular selection path. However, the summation of all selection paths did not differ much among crossbreeding systems. Progeny testing decreased CDE by increasing generation intervals. The CDE for reproduction traits were higher than those for production traits mainly as a result of earlier expression of the reproduction traits.