the objective of this study was to assess the discounted genetic expressions (dges) for different categories of animal traits as regards holstein cattle of iran. using discounted gene-flow principles, dges per calf born were estimated for self replacing females and also for their sires. in the situation for sires of self replacing females, relative gdes per cow per year for annual cow traits, t...

The objective of present study was to derive the economic values for number of inseminations to conception, calving interval, milk yield and stillbirth, using economic data of 10 Iranian Holstein herds. The economic values were derived by using the profit function methods and differentiating a profit equation with respect to the traits of interest. The cow fertility costs herd amortization or r...

In Australia, dairy cattle account for ~12% of the nation’s agricultural greenhouse-gas (GHG) emissions. Genetic selection has had a positive impact, reducingGHGemissions fromdairy systemsmainly due to increased production per cow,which has led to (1) requiring fewer cows to produce the same amount ofmilk and (2) lowering emissions per unit of milk produced (emission intensity). The objective o...

Maternal performance of 134 Hereford (H), Brangus (B), and reciprocal crossbred (H x B and B x H) cows from 2 to 7 yr of age was evaluated under semidesert conditions in this study. Calves produced by 2- and 3-yr-old cows were sired by Brangus and Hereford bulls. Calves produced by 4- to 7-yr-old cows were sired by Charolais bulls. Breed of sire and breed of dam of cow affected kilograms of wea...

In Australia, dairy cattle account for ~12% of the nation’s agricultural greenhouse-gas (GHG) emissions. Genetic selection has had a positive impact, reducingGHGemissions fromdairy systemsmainly due to increased production per cow,which has led to (1) requiring fewer cows to produce the same amount ofmilk and (2) lowering emissions per unit of milk produced (emission intensity). The objective o...

A total of 72124 fertility records was used to estimate the genetic and phenotypic trend of fertility traits in Iranian Holstein cow from 1981 to 2007. Fertility traits in this study were: days from calving to first service (DFS), number of insemination per conception (INS), days open (DO), interval between first and last insemination (IFL), calving interval (CI) and success to first inseminati...

The concept of extended lactation should improve cow health and productivity while reducing greenhouse gas emissions per kg milk produced in high-yield organic dairy herds. This is achieved through fewer calvings per year and hence production of fewer replacement heifers. Combined with fewer days dry per cow per year, this will reduce the annual herd requirement for feed while maintaining milk ...

the financial losses, absolute and net economic values (evs) for direct (dcd) and maternal calving difficulty (mcd) were estimated using a bioeconomic model and taking into account the categorical nature of the trait. the effects of dystocia on other traits were estimated. but because of low reliability they were not considered for calculations in the base situation. in the base situation, the ...

the aim followed in the present study was to investigate the economic aspects of , and to derive economic weights (ews) for mature body weight (mbw) as well as for age at first calving (afc) in holstein dairy cattle of iran. economic values (evs) for traits were estimated using trait-by-trait bio-economic models. absolute evs were rls -16400 and -17900 per cow per year for mbw and afc, respecti...

Eight 4-ha mixed warm-season grass pastures in southwestern Arkansas (33°40'4″ N, 93°35'24″ W, and elevation 107 m) were stocked with either large mature size (571 kg [SD 55.2] BW) or small mature size (463 kg [SD 58.2] BW) spring-calving cows at 4 stocking rates (SR; 1, 1.5, 2, or 2.5 cow-calf pairs/ha) over 4 yr to test the effects of SR and mature body size on cow and calf performance and sy...