Sexual segregation outside the mating season occurs in most species of sexually dimorphic ungulates and has been extensively described in the literature, but the mechanisms causing segregation are still debated. The detailed pattern of sexual segregation throughout the year has rarely been presented for mammals, and no study, to our knowledge, has used latitudinal-related variation in breeding ...

Data on weaning weight from 12,740 animals were used to compare different contemporary group (CG) definitions to be applied in the current genetic evaluation in the Avileña Negra Ibérica beef cattle breed. Several classical ‘ad-hoc’ statistics and criteria for statistical model comparison within a Bayesian analysis were used. Six alternative definitions for the CG effect were compared: Herdyear...

Calving difficulties were examined in pure-bred Charolais, Limousin, MaineAnjou and Hereford cattle maintained in stalls at Bourges, France. The cows were born in 1970 and raised together from weaning. Records of calving performance, birth weights, gestation lengths and dam weights after calving from 2 to 5 years of age were analysed to compare breeds and to estimate maternal and direct genetic...

Genetic evaluations provide information to aid in breeding decisions that increase long-term performance of animals and herds. However, to date no study has been undertaken to investigate the accuracy of the Irish maternal genetic evaluations in beef cattle. The objective, therefore, of this study was to quantify the relationship between phenotypic performance and measures of genetic merit for ...

Objectives were to determine effects of lasalocid on reproductive performance and serum concentrations of leptin and IGF-I, and to correlate concentrations of leptin and IGF-I with reproductive performance of beef cows. Forty-one purebred, multiparous Brahman cows were blocked to control (C; n = 20) or lasalocid (L; n = 21) treatments by BW, BCS, and predicted calving date. Treatment began 21 d...

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...

Because of difficulties in data collection and analysis, in most breeds there have been limited ways to evaluate fertility in females on a between-herd basis. The objective of this study was to determine the heritabilities (direct and maternal) for CD (calving day) and AFC (age at first calving) in American Angus heifers and to evaluate the potential for using these traits in genetic improvemen...

The objective of this study was to investigate the genetic relationship between body condition score (BCS) and reproduction traits for first-parity Canadian Ayrshire and Holstein cows. Body condition scores were collected by field staff several times over the lactation in herds from Québec, and reproduction records (including both fertility and calving traits) were extracted from the official d...

Determining a calving law valid for all glaciological and environmental regimes has proven to be a difficult problem in glaciology. For this reason, most models of the calving process are semiempirical, with little connection to the underlying fracture processes. In this study, I introduce methods rooted in statistical physics to show how calving laws, valid for any glaciological domain, can em...

This study was designed to investigate causes of culling in industrial dairy herds in Fars province and to describe the pattern of reason-specific culling with respect to age of animal and interval from calving to culling. A total number of 9 dairy herds were selected for the study and information about culling reasons, birth date, last calving date and culling date was collected for culled cow...