The influence of paratypical factors (the age mothers and the season birth) on indicators reproductive qualities black-and-white cows different periods has been studied. studies were conducted two groups for first third lactation, depending mothers, four – birth season. shortest service period was characterized by first-born heifers born from mother in calving (group I) - 96.4 days, which is 9....

in the research the genetic investigation productive and reproductive traits and changes trend the traits in years, seasons and different lactation periods and genetic evaluation cows and bulls of 785 records for milk and 665 records for fat yield and reproductive information during years 1998 to 2003 of 207 dairy cows ghezlagh farm aboureyhan campus (university of tehran) studied. the least sq...

the objective of the present study was to estimate genetic trends for lactation milk yield, persistency of milk yield, somatic cell count and interval between first and second calving in holstein dairy cows of iran. the dataset consisted of 210,625 test day and 25,883 first parity cows with milk yield recorded from july 2002 to september 2007 comprising 97 herds in iran. breeding values of anim...

Spring-calving Brahman cows (S) artificially inseminated to Brahman, Angus, or Tuli sires and fall-calving Brahman cows (F) naturally bred to Brahman were allotted randomly to receive 3.74% (LF; n = 9 S and 6 F), 5.20% (MF; n = 8 S and 6 F), or 6.55% dietary fat (HF; n = 8 S). Diets were formulated to contain differing fatty acid concentrations and to be isocaloric and isonitrogenous. Cows were...

Factors affecting calving interval (CI) in double-muscled Belgian Blue (DMBB) beef cows were investigated with regard to the BW yield (BWY) of the cow-calf pair, using 834 CI records from 386 females with parities 1 to 6. The effect of parity and CI on BWY was also studied. Cow-calf pair BWY was defined as calf birth weight plus dam BWY per CI. CI (mean±s.e.: 404±1.9 days) was affected by parit...

The problem of postpartum anoestrus is a real one because it results in prolongation of the time between calvings. The interval between the calving and resumption of cyclic ovarian activity depends on several factors, i.e., amount of feeding before and after parturition, level of milk yield, age of the animal, calving difficulty, presence of a bull in the herd, season and its photoperiodism and...

Test day (TD) records of milk production traits (milk yield, fat, and protein percentages) of 534 Italian buffalo cows were analyzed with a mixed linear model in order to estimate lactation curves pertaining to different ages at calving and different seasons of calving. Milk yield lactation curves of younger animals were lower than those of older animals until 20 wk from parturition. No effect ...

A total of 5852 records concerning daily milk yield, content of protein and fat, and somatic cell count was recorded in two farms (organic and conventional). Somatic cell count was log10transformed before analysis because was not normally distributed. The mixed model methodology was used according to a repeated-measures scheme, as the restricted maximum likelihood method to estimate lactation c...