The purpose of this review is to define possible breeding objectives for Southern African beef cattle farmers and to review different means of expressing genetic reproductive merit. The breeding objective considered was to maximize the number of calves born or weaned for a given number of cows in a herd under prevailing environmental and management conditions. This is a complex trait that has m...

Data containing 14,188 lactation and reproductive records of Korean Holstein cows at first parity distributed across 3,734 herd-year-season groups were analyzed to get genetic (co)variance estimates for milk yield, fat yield, calving ease, and days open. Milk and Fat yields were adjusted to 305 d. Heritabilities and genetic correlations were estimated in two different animal models on which wer...

Economic values for calving performance in first and later parities were estimated for the Piemontese cattle. Calving performance is a threshold trait usually recorded using a scoring system with categories corresponding to the rate of difficulty. In the Piemontese breed five categories were adopted (from unassisted to foetotomy). A normal underlying distribution with thresholds corresponding t...

Social influence has been shown to profoundly affect human behavior in general and technology adoption (TA) in particular. Over time, multiple definitions and measures of social influence have been introduced to the field of TA research, contributing to an increasingly fragmented landscape of constructs that challenges the conceptual integrity of the field. In this vein, this paper sets out to ...

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...

Longevity and lifetime productivity are important factors influencing profitability for the cow-calf producer. Heifers that conceive earlier in the breeding season will calve earlier in the calving season and have a longer interval to rebreeding. Calves born earlier in the calving season will also be older and heavier at weaning. Longevity data were collected on 2,195 heifers from producers in ...

A 5-yr study was conducted beginning in 1983 with 460 cows to evaluate the effects of three breeding seasons (30, 45, and 70 d in length) and two times of spring calving, March (early) and April (late), on cattle production under Nebraska Sandhills range conditions. Criteria evaluated included pregnancy and weaning percentages, calving date and distribution, cow weights and body condition at fo...

This experiment was conducted to determine the association between several risk factors which may affect culling of the Iranian Holstein cows. The data consisted of 329,772 lactation records collected by the Animal Breeding Center of Iran (2003 to 2012).The logistic regression was applied to investigate the associations between the response variable, the risk of culling, and predictor variables...

economic data and performance records from 10 iranian holstein dairy cattle herds, as well as milk production and fertility records from iranian center of animal breeding and animal production improvment were used to estimate the effect of calving difficulty on milk production, fertility and as well on the economic aspects of maternal and direct calving difficulty. calving difficulty could be d...