Samenvatting (in Engels)
One of the challenges in dairy cattle is to have an efficient animal, an animal that produce the same amount of milk consuming less feed, and producing less methane without to affect their body condition and health. This used to be achieved by genetic selection, that means selecting animals based on the perform or their parents, daughters and themselves (via pedigree). The disadvantage of this method was the time required, given that each bull to be proved good, needed to have the perform of at least 100 daughters, and that was time and cost consuming. Nowadays, new tools like DNA markers can be used to know how an animal will perform since this animal is born, helping you to reduce the interval inter-generations, and producing more precise evaluations.
Animal breeding has changed from selection for productivity to selection for many traits i.e. production, health, fertility and longevity. A new challenge is resources efficiency. Can we breed healthy cows that produce same amount of milk, but consuming less feed, and producing less methane? In this thesis we investigated how we can breed cows that use resources more efficiently. First, by investigating the genetics of feed intake and its relationships with live weight and productivity during lactation. Second, using data from the Netherlands and the United States we investigated the value of commonly recording linear type traits for the prediction of live weight and different definitions of feed efficiency. Third, we investigated the genetics of methane emissions and its correlation with feed intake and live weight in Australian dairy and beef cattle. Finally, we tested a novel model that combines this information with DNA markers to predict the breeding values of cows for feed intake.