calving records from april 1998 to september 2006 comprising 104,572 calving events from 16 dairy herds of iran were used to analyze the potential effect of dystocia on calf stillbirth and productive traits in iranian holsteins. statistical analyses of production traits were performed using a linear mixed model procedure. also, a logistic regression model was constructed to analyze the effect o...

the present study aimed to estimate the effects of parity, calving season and year of calving on the prevalence of subclinical mastitis in holstein cows. a total of 2682 records from 869 holstein cows in a large dairy farm (azarbaijan province, iran), respecting the period from 2006 to 2009, were collected. data was analyzed using proc mixed of sas software by mivque method. subclinical mastiti...

The objective of this study was to quantify how the pattern of milk production relative to time from calving is affected by parity in cows fed high quality rations. For this purpose two models; those of Emmans and Fisher (1986) and Dijkstra et al. (1997), were considered. Comparison with Wood’s (1967) function was made to evaluate their fitting ability. Daily records of milk yield from 40 cows ...

A better understanding of changes in plasma amino acid (AA) concentrations during the transition period may help optimize nutrition to improve health, welfare, and production dairy cows. The aim this study was assess AA Holstein cows first-lactation heifers. Blood samples for analysis were collected from tail vein/artery 9 multi- 8 primiparous 3 weeks prior at 1, 2, post-calving. Concentration ...

The objectives of this study were to evaluate the functional properties of immunocompetent cells in dairy cows fed diets enriched in n-3 or n-6 polyunsaturated fatty acids during the transition period. Six weeks before calving, 21 primiparous and 27 multiparous pregnant Holstein dairy cows were randomly allotted to 1 of 3 dietary fat treatments: calcium salts of palm oil (Megalac), micronized s...

Breeding objectives for beef cattle in Ireland were derived and used to define selection sub-indexes. The intention of the sub-indexes was to simplify selection decisions by commercial bull and semen buyers for situations where all of the resulting progeny are slaughtered, or when some female progeny are kept as replacement breeding cows. Separate sets of economic values for calving ease and ge...

Transfer of sufficient immunoglobulin G (IgG) to the neonatal calf via colostrum is vital to provide the calf with immunological protection and resistance against disease. The objective of the present study was to determine the factors associated with both colostral IgG concentration and colostral weight in Irish dairy cows. Fresh colostrum samples were collected from 704 dairy cows of varying ...

Reproductive efficiency in the dairy herd is the most important factor for its economic success and a major concern for dairy farmers when using artificial insemination (AI) or natural service (NS). Our objectives were to estimate, compare and analyse the costs associated with breeding cattle by do-it-yourself (DIY) AI and NS and identify the factors that influence them, under typical dairy far...

It is unclear why some cows fail to expel the placenta following calving. One theory suggests the fetal placenta must be recognized as "foreign" tissue and rejected by the immune system after parturition to cause expulsion of the placenta. We hypothesized that impaired neutrophil function causes retained placenta (RP). We examined the ability of neutrophils to recognize fetal cotyledon tissue a...

Genomic selection has revolutionized dairy cattle breeding. Since 2000, assays have been developed to genotype large numbers of single-nucleotide polymorphisms (SNPs) at relatively low cost. The first commercial SNP genotyping chip was released with a set of 54,001 SNPs in December 2007. Over 15,000 genotypes were used to determine which SNPs should be used in genomic evaluation of US dairy cat...