than to calf birth weight alone. Percent calving difficulty is the percentage of births requiring assistance from the herdsman. Calving scores of3 or higher were classified as difficult births based on a scoring system ranging from I = no assistance to 5 = caesarian birth or abnormal presentation. Due to the substantially higher incidence of calving difficulty in 1978 over 1979 (11.3 percent vs...

The growth endocrine axis influences reproduction. A QTL associated with enhanced ovulation exists on chromosome 5 in cattle and there are 6 genes underlying this region involved in the mechanisms of GH action. Resequencing exons, 5’ and 3’ untranslated regions and conserved non-coding regions of these genes in a multibreed resource population revealed 75 SNP usable for genotype to phenotype as...

Trait-by-trait and multiple trait bioeconomic modeling were used to derive farm-specific economic weights (EW) for a wide range of traits under different production and economic circumstances to define breeding objectives for Holstein dairy cattle in Iran. Production parameters and economic data were gathered on 10 dairy farms from March 2008 to February 2010. The EW (economic values multiplied...

producers. This loss is estimated at $750 million annually nationwide. Calving difficulty increases calf death loss, cow mortality, labor and veterinary costs; it delays the return of cows to estrus and reduces conception rates. It also lowers calf weaning weight and market value, which results from breeding of young heifers and cows to easy calving bulls to reduce calving difficulty. Studies s...

ABSTARCT The objective of this study was to analyze the effects of factors affecting reproductive traits in the Holstein population of the Isfahan dairy farms for subsequent compilation of the model for genetic evaluation as well as for herd management practice. A data set containing 99012 records were analyzed by a linear model with fixed effects of year , herd ,season, parity of dam, calving ...

The combination of the Pine Island Ice Shelf (PIIS) draft and a seabed ridge beneath it form topographic barrier, restricting access warm Circumpolar Deep Water to cavity inshore ridge, thus exerting an important control on PIIS basal ablation. In addition, has recently experienced several large calving events further could significantly alter geometry. Changes in ice front location, together w...

The main reason for calving replacement heifers early is economics. Economic assessments (2) have demonstrated that heifer rearing cost increases $50.00 to $60.00 each month calving is delayed. In addition, older calving ages result in the need for more heifers for herd replacement. These classic concepts are presented in Table 1. Conceptually, as calving age is reduced there is a linear reduct...

Calving in cattle is affected by calf morphology and by dam characteristics. It is described by two different traits: maternal calving ease, which is the ability to generate dams with good physiological predisposition to calving, and direct calving ease, which is the ability to generate calves that are easily born. The aim of this study was to identify regions of cattle genome harboring genes p...

During the periparturient period, some impairment of immune defences were observed. Reference values for the different non-specific immune parameters in cows are not generally available, thus limiting the application of these parameters in dairy practice. This paper reports the data on the measurements of different parameters in the blood, and explores the possible influence of the herd on the ...

One hundred forty-three crossbred, fall-calving first-calf heifers were used to determine the effects of two levels of energy and two levels of lasalocid on cow-calf productivity. Diets fed for approximately 110 d prepartum were calculated to provide a daily intake of 15.3 (LE) or 18.0 (HE) Mcal ME; diets fed for approximately 130 d postpartum were calculated to provide a daily intake of 17.8 (...