The objective of this study was to investigate the effect of birth weight (BW) on future milk production and reproductive performance in Iranian Holstein cattle. Records of Holstein cows between 1967 and 2010 were obtained from the Animal Breeding Center of Iran. Birth weights within each herd were grouped into five categories based on the standard normal distribution curves (z ≤-0.8416, -0.841...

The objectives of the study were to compare the ovarian activity of Holstein-Friesian (CH HF), Fleckvieh (CH FV) and Brown Swiss (CH BS) dairy cows of Swiss origin with that of Holstein-Friesian (NZ HF) dairy cows of New Zealand origin, the latter being used as a reference for reproductive performance in pasture-based seasonal calving systems. Fifty, second-lactation NZ HF cows were each paired...

The objectives of this work were to compare reproduction and parturition traits of the Criollo breed Romosinuano as straightbred and crossbred cows with Angus and Brahman, to estimate heterosis and direct and maternal genetic breed effects, and to describe calf loss, cow removals from the project, the occurrence of calving difficulty, inadequate calf vigor at birth, and udder problems by cow br...

Whether to select for longer life in the herd or shorter calving interval depends on the genetic and phenotypic relationships among herd life, amount of milk in first lactation, and calving interval. Herd life and average calving intmwal are essentially phenotypically uncorrelated. The phenotypic and genetic correlations of herd life and milk in first lactation ranged from .19 to .25 and from ....

The objective was to quantify the strength of the relationship between body condition score (BCS) and live weight (LW) in pasture-based Holstein-Friesian dairy cattle, and to determine the kg LW per unit BCS. A total of 26021 test-day records with information on both BCS (1-10 scale, where 1 is emaciated and 10 is obese) and LW across 1110 lactations from one research farm were used in the anal...

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...

Mastitis is one of the most important diseases affecting production and reproductive efficiency dairy cows. The objective this study was to estimate prevalence subclinical mastitis (SCMA) its effects on performance in postpartum In a cross-sectional survey, sample cows (n = 200) within their 10-40 days milk from smallholder farms 159) were selected tested for SCMA using California Test. They cl...

The effect of calving ease on the fertility and production performance of both dam and calf was studied in approximately 50,000 and 10,000 UK Holstein-Friesian heifers and heifer calves, respectively. The first objective of this study was to estimate the effect of a difficult calving on the subsequent first-lactation milk production by estimating lactation curves using cubic splines. This metho...

four hundred and ninety five smallholder dairy farms in 52 villages of different cities in chaharmohal and bakhtiari province including 1321 lactating cows and totalling 2811 total mature cows (lactating and dry)were employed during winter 2009 to summer 2010 to estimate the economic opportunities as per cow in smallholder dairy farms. a questionnaire survey was employed to collect data from th...