Dairy cows are extremely inefficient at converting dietary nitrogen (N) to productive N. Approximately 25-30% of dietary N is used for milk protein while the remaining N is lost to the environment. According to National Research Council (NRC, 2001) recommendations, dairy cow rations are formulated in terms of metabolizable protein (MP) which often causes many amino acids (AA) to be fed in exces...

The decline of dairy cattle fertility worldwide remains a major concern, with conception rates to first service commonly below 40%. The length and severity of negative energy balance postpartum are unfavorably correlated with fertility, suggesting that the length and severity of negative energy balance and fertility are linked via several hormones or metabolites. These compounds therefore have ...

Dairy cattle breeding programs have been based in the selection for traits related to milk production. In this research a data set of 63 herds of East Azerbaijan province Holstein cattle, collected during 2002-2013 by the Iranian Animal Breeding Center was used to estimate the repeatability and heritability of three traits of economic importance. Genetic parameters for first three lactations of...

Sahar, Mohammad W. M.S., Purdue University, December 2014. Growth of PostWeaned Grazing Dairy Heifers when Evaluating the Effects of Providing Shade or Parasite Control. Major Professor: Tamilee Nennich. Reduced heat stress and lower gastrointestinal parasite loads can increase growth rate in heifers, potentially reducing the age at first breeding and lowering the costs associated with raising ...

SUMMARY In dairy cattle breeding, genetic relationships among lactatio are of special interest because most selection operates on first la: This selection also complicates estimation of genetic Techniques which give estimates unbiased by selection should Estimation was done using EM-type REML for an animal relationships across herds. Records were from 3,070 Holstein cows the first lactation rec...

Future progress in genetic improvement and the monitoring of genetic resources in beef cattle requires a detailed understanding of the population under selection. This study examines the gene flow in the UK beef population with an uncommon breeding structure involving interaction between the beef and dairy populations. British Cattle Movement Service records were used as the primary source of i...

The objective of the present study was to estimate genetic correlations between feed intake and type traits with a view to considering the potential of indirect genetic selection for feed intake using type traits in dairy cattle. Feed intake data on 119,388 first lactation Holstein cows were obtained from Dairy Production Centre of Expertise, Valacta. Type trait records on 93,619 cows were obta...

The objective of the present study was to determine factors affecting body condition score (BCS) and its association with productive and reproductive performances in Holstein cows. Mixed model analysis was performed on monthly records of BCS from April 2006 to July 2012 comprising 34666 records from 3134 dairy cows in a large commercial dairy herd under arid climatic conditions of Isfahan in Ir...

The study was carried out on 120 crossbred Holstein × Shahiwal dairy cows for a period of 150 days to quantify the influence of dietary energy and protein intake on yield and composition of milk. Total 12 dairy farms having similar housing systems and holding at least 20 dairy cows in between mid to late lactation were selected for study purposes. The farms were located in the peri-urban and ur...