Holsteins are the most common dairy breed throughout the world. They have been genetically improved to produce a higher yield to become more profitable for the dairy industry. The first Holstein originated in Europe approximately 2000 years ago (1). They emerged from the Netherlands in the provinces of Northern Holland and Friesland. Interbreeding of the black Batavian cattle and the white Friesian cattle created a black and white cow that could make use of the rich pasture lands of the Rhine region. Such interbreeding allowed the ability of the Batavian cattle’s digestive system and the Friesian cattle’s body and udder size to produce an efficient and high producing dairy cow (1).
Holsteins are a versatile breed of cattle. They are adaptable to all types of different utilizations. This breed can thrive in both barn and pasture life or a mixture of both throughout the year. With such versatility, Holsteins are resistant to stress and produce strong and hearty calves that have a rapid growth and an early maturity rate. Although Holsteins are resistant to stress, they do show intolerance to heat and disease. The consequence of such intolerance is a reduction in milk productivity (1).
Even with a naturally high milk production, years of selective breeding has increased this yield further. Since the 1960s, the U.S. dairy industry dramatically improved selective breeding efforts, helping double milk production (2). With this major development, it is likely that genetic improvements can increase 1% to 2% per year (1). Presently, 30% of the Holstein’s genome has been modified by selective breeding procedures. These modifications can be illustrated by an increase in milk production. Between 1957 and 2007, milk production increased by 5,997 kg per cow in the United States, with approximately 3,390 of those kilograms due to genetics. This is a 56% increase due to genetics and selectively breeding for a greater milk yield. Other countries have found the same results. In Austria, between 1988 and 2007 Holsteins increased from 5,550 kg to 8,200 kg. The United Kingdom also had an increase of approximately 200 kg per year, with half of the improvement due to genetics (3). Today, Holsteins produce an average of 9,072 kg to 10,607 kg of milk per year, along with 389 kg of butterfat and 326 kg of protein per year (4). Similarly, a top yielding cow has been recorded to have produced 30,805 kg of milk per year (1). Looking at the average milk yield increase in Holsteins, it is obvious that selective breeding is genetically altering dairy cattle for economic and financial purposes.
Although originally bred for docility and manageability, breeding programs have become increasingly focused on improving Holstein production traits such as milk yield and growth rate. Before major advances in genetic research began, selective breeding started by choosing a desired phenotype in the parent and hoping that the offspring’s phenotype would be similar. For this reason,...