OBJECTIVE To examine the effects of Rhodobacter sphaeroides (R. sphaeroides) supplementation as a direct-fed microbial (DFM) on rumen fermentation in dairy cows and on coenzyme Q10 (CoQ10) transition into milk, an in vitro rumen simulation batch culture and an in vivo dairy cow experiment were conducted. METHODS The characteristics of in vitro ruminal fermentation were investigated using rume...

Effects of age at first calving (AFC) on functional longevity of Czech Holstein cows and their reproduction traits in the first lactation were analyzed using the first lactation data of 605 538 Holstein cows first calved from 1993 to 2008. Three classes were formed for AFC: low age class (16–24 months), average age class (25–30 months), and high age class (33–46 months). Effects of AFC on lengt...

The size distribution and protein composition of casein micelles in the milk of Holstein-Friesian cows was determined as a function of stage and number of lactations. Protein composition did not vary significantly between the milks of different cows or as a function of lactation stage. Differences in the size and polydispersity of the casein micelles were observed between the milks of different...

To evaluate the effects of chelated Zn/Cu/Mn on redox status, immune responses and hoof health in lactating Holstein cows, 48 head in early lactation were divided into healthy or lame groups according to their gait score. Cows were fed the same amount of Zn/Cu/Mn as sulfate salts or in chelated forms for 180 days, and foot-and-mouth disease (FMD) vaccine was injected at day 90. The results show...

the aim of this study was to evaluate total iodine, triiodothyronine (t3) and thyroxine (t4) status in the blood serum of holstein cows on six farms in central iran. total iodine, t3 and t4 concentrations were measured in 90 blood serum samples (15 per farm). mean concentrations of total iodine (38.80 ± 1.52 µg/l) and t3 (1.57 ± 0.10 nmol/l) were lower but the mean concentration of t4 (45.60 ± ...

The objective of this study was to evaluate the effect of ruminally protected amino acids (RPAAs) and ruminally protected fat (RPF) supplementation on ruminal fermentation characteristics (in vitro) and milk yield and milk composition (in vivo). Fourteen mid-lactating Holstein dairy cows (mean weight 653±62.59 kg) were divided into two groups according to mean milk yield and number of days of p...

Milk and serum samples from 35 dairy herds in 17 states were evaluated for cow- and herd-level Mycobacterium avium subspecies paratuberculosis (MAP) antibody test agreement. Evaluation of 6,349 samples suggested moderate agreement between milk and serum enzyme-linked immunosorbent assay (ELISA) results, with a kappa value of 0.50. Cow-level sensitivity (Se) for 18 dairy operations with 1,921 an...

Estimated genetic values from an animal model based on first lactation milk records for 6OOO AI Holstein sires and 1,074,971 Holstein cows born in 1981 or before were used to estimate average genetic selection differentials and generation intervals for the four paths of selection for each year of birth. Selection differentials for paths of sires of bulls, dams of bulls, sires of cows, and dams ...

In this study we estimated the allele and genotype frequencies of SCD1 and DGAT1 gene polymorphism. The analysis was conducted on 408 Holstein cows from five dairy herds in Isfahan province. Genotypes were identified using PCR-RFLP technique. Two genetic variants (A and V) of the SCD1 gene were observed in this experiment. The frequency of A-allele ranged from 0.49 to 0.66, while frequency of V...

The infusion of ozone into the inflamed quarter of cows with clinical mastitis was performed and the efficacy of ozone therapy was evaluated. Ozone was infused into the inflamed quarter via a teat canal using ozone gas generating equipment. Nineteen Holstein cows with acute clinical mastitis were divided into two groups: 15 cows treated with ozone therapy, and 4 cows treated with antibiotic the...