Genetic Improvement of Dairy Cow Reproductive Performance

Abstract

The welfare of cow along with profitability in production are important issues in sustainable animal breeding programmes. Along with an intense/intensive selection for increased milk yield, reproductive performance has declined in many countries, in part due to an unfavourable genetic relationship. The largely unchanged genetic trend in female fertility and calving traits for Scandinavian Red breeds shows that it is possible to avoid deterioration in these traits if they are properly considered in the breeding programme. Today's breeding is international with a global selection and extensive use of the best bulls. The Nordic countries have traditionally recorded and performed genetic evaluation for a broad range of functional traits including reproduction. In recent years many other countries have also implemented genetic evaluation for these traits. Thus, the relative emphasis of dairy cattle breeding objectives has gradually shifted from production to functional traits such as reproduction. Improved ways of recording traits, e.g. physiological measures, early indicator traits, assisted reproductive techniques and increased knowledge of genes and their regulation may improve the genetic selection strategies and have large impact on present and future genetic evaluation programmes. Extensive data bases with phenotypic recordings of traits for individuals and their pedigree are a prerequisite. Quantitative trait loci have been associated to the reproductive complex. Most important traits, including reproduction traits are regulated by a multitude of genes and environmental factors in a complex relationship, however. Genomic selection might therefore be important in future breeding programmes. Information on single nucleotide polymorphism has already been introduced in the selection programmes of some countries.

Risk factors associated with dystocia in a tie stall dairy herd

“…In the present study, the prevalence of dystocia was 32.1% in primipaorus and 8.5% in multiparous cows. Therefore, it could be acknowledged that although genetic selection in dairy cattle has historically focused mainly on milk production, in recent years it has been more divergent and has considered other factors such as health, fertility, and calving ease (Hansen 2000;Berglund 2008;Mee 2008aMee , 2008b. However, the prevalence of dystocia and stillbirth remain unacceptably high, and inappropriate sire selection seems to be a big part of the problem.…”

Effects of inbreeding and other genetic components on equine fertility

“…The magnitude of heritability for fertility traits is similar in several species. In cattle, for example, despite the low heritability, breeding programs have improved fertility, as reviewed by Berglund (2008). A similar progress should be possible in horses as well, but in practice, fertility traits of horses are often considered to be of less value than performance traits.…”

Genetic parameters for fertility measurements in Holstein heifers: The activity tag Heatime makes a difference

“…Since 1984, the milk production in Denmark has increased around 3000 kg/cow/year mainly due to selection for high yield (Sørensen et al, 2006), and it is known that there is a negative genetic correlation between milk yield and fertility (Pryce et al, 1999;Berglund, 2008;Buch & Norberg, 2008;Buch et al, 2011). As a result of selecting for high milk yield, there has been a decline in reproductive performance in the last three decades (Berglund, 2008).…”

“…As a result of selecting for high milk yield, there has been a decline in reproductive performance in the last three decades (Berglund, 2008).…”