birth weight (bw) is the first trait recorded fllowing birth. it can influence the performance of thecow and as well impact the performance of the calf it,s duringits maturity. to investigate the effect ofa calf,s bw on the performance of holstein dairy cattle in iran, the records gathered between 1967 and2010 were obtained from the iranian animal breeding center. the data were then used to mod...

Leptin and leptin receptor genes are considered as production traits markers in dairy or beef cattle. The aim of this study was to verify the associations of polymorphisms in bovine LEP and LEPR genes with production and reproduction traits in Slovak Spotted and Pinzgau cows. Long-life production was evaluated: milk, protein, and fat yield and reproduction traits: age at first calving, calving ...

A 2-yr study using primiparous and multiparous, spring-calving, crossbred beef cows was conducted to evaluate the effects of supplemental whole corn germ on reproductive performance, calf performance, and serum leptin concentrations. Each year, cows were blocked by age and BCS and assigned randomly to one of three treatments: PRE (n = 115) cows received 1.14 kg/d (DM basis) of whole corn germ f...

The milk yield and survival of 91 Holstein-Friesian dairy cows that had had a left-displaced abomasum (LDA) corrected laparoscopically were compared with those of 193 control cows matched for herd, parity and calving date. Ninety per cent of the LDA treatments were performed within four weeks after calving. The risk of being culled during the whole observational period of at least three years w...

In the Netherlands a fertility index is introducing which describes the fertility of daughters of a bull. The index is based on two breeding values which are estimated for all bulls; non return after 56 days (NR56) and interval between calving and first insemination (ICI). These two traits are combined in an index: the calving interval index or CI-index. This index was developed after comparing...

In modern high-yielding dairy herds fertility is of major economic importance. In order to gain maximum profit, calving intervals should not exceed 365 days. The achievement of a 365-day calving interval requires an early resumption of ovarian activity, an excellent oestrus detection, and a high first-service conception rate. Especially the inability to detect oestrus and to mate the cows by 60...

Procedures for breeding value estimation for reproductive traits under pasture mating conditions were developed and tested using a computer simulation model of genetic control of bovine reproduction. The model generated annual calving rates (BCR) (0 or 1) and calving dates (CD) for each cow as a function of underlying genetic variation in two independent traits: single-service conception rate, ...

The objective of the present work was to analyze evolution productive indicators over time in Nelore cows Bolivian tropics. period between 1991 and 2016, corresponding 3899 calvings were used for research which belong Technology Center on Agriculture Livestock Bolivia belonging (FUNDATION CETABOL) Cooperativa Agropecuaria Integral San Juan de Yapacaní used. Cows ordered by birth into...

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...