Direct reproductive traits as they are currently measured tend to be low in heritability, making the environment a beef female is produced in key to reproductive success. Large cow size and high milk production translate into increased energy and protein requirements for the cow, even when not lactating. The increased nutrient requirements can significantly limit the carrying capacity of any fa...

The objective of this research was to partition phenotypic variation in calf gain from birth to weaning, and milk production measured, by the weighsuckle-weigh method, and udder score of cows into genetic and nongenetic components. Data were from the Line 1 Hereford population maintained by USDA-ARS at Miles City, MT, and included observations of preweaning gain (n = 6,835) from 2,172 dams, mil...

Positional, comparative candidate gene analysis and previous quantitative trait loci linkage mapping results were used to search for candidate genes affecting milk production and reproduction traits in dairy cattle. The protease inhibitor (PI) gene was chosen for examination, and 5 single nucleotide polymorphisms were detected in coding regions of the gene by direct sequencing of reverse transc...

Context Cow survival measures the ability of cows to survive from current subsequent lactation. In addition economic gain, genetic selection for could improve animal welfare by increasing adaptability and resilience both environmental health challenges. However, is a complex trait because it results diverse range reasons culling herd. Consequently, accuracy predictions direct are often low. Aim...

Prediction of lactation yields and accuracies of yields for use in genetic evaluation can be improved by including information from test day correlations, especially for milk recording plans that vary in the numbers of milk weights recorded and component samples taken. Daily milk weights for 658 lactations of Canadian cows and monthly test records of milk, fat, and protein yields and somatic ce...

Most important economic trait milk constituents include fat, protein, SNF, lactose and ash. Being rich in these components, milk is considered as one of the essential foods all over the world. Amongst the milk constituents, β-casein has gained importance and popularity in the health conscious people due to its recent health related issues. The status of A1 or A2 beta casein variants in Bos taur...

The direction of the breeding process in herds and populations dairy cattle breeds based on actual indicators variability trait is one main factors that allows to determine effectiveness measures. As initial material for research there were taken data records (n=681) Ayrshire breed cows agricultural complex "Maysky" Vologda region. number was distributed by generations (195 with first incomplet...

Change is the major trend in today’s genetics. We are nearing the end of a 30 to 40 year era of rapid genetic progress for milk production and conformation, particularly in udder structure. We are entering an era when traits such as fertility, health, and survival have are becoming more valuable than they were in the recent past. These developments are influenced by strong industry trends towar...

Milk yield per cow has more than doubled in the previous 40 years and many cows now produce more than 20,000 kg of milk per lactation. The increase in production should be viewed with concern because: i) the increase in milk yield has been accompanied by declining fertility, increasing leg and metabolic problems and declining longevity; ii) there are unfavourable genetic correlations between mi...