Dietary supplementation of lactating dairy cows with fat has long been used as a management tool to increase the energy density of feeds, improving milk production, reproduction and alleviating the menace of postpartum negative energy balance. In this paper, we show that while attempts have been made to investigate the effects of omega-3 (n-3) polyunsaturated fatty acid (PUFA) on reproduction a...

Data from insemination and calving events of Italian Holstein cows and heifers collected from January 1996 until December 2002 were used to estimate phenotypic and genetic parameter for some fertility traits. A validation procedure of the data based on gestation length and information on service sire was used. According to these procedure, in Italy 75.9 % of the calvings are associated to servi...

During the past several decades, selection for increased milk yield has had a temporal association with declines in fertility and reproductive efficiency in dairy cows. In the US, an average annual decrease of 0.5% in conception rate at first service occurred between 1975 and 1997 (Butler and Smith, 1989; Beam and Butler, 1999). In the UK (between 1978 and 1996) and in Spain (between 1991 and 2...

The Dixit entry/exit real option model was applied to the entry/exit decisions of New York dairy farmers. For the cost structure of a 500-cow farm the entry milk price is $17.52 per hundredweight (cwt.) and the exit milk price is $10.84. For the 50-cow farm cost structure the entry price is higher at $23.71 per cwt., and the exit price is also higher at $13.48. If infinite numbers of representa...

Commercial cow-calf producers have an increasing number of options available for the synchronization of estrus and ovulation to facilitate the incorporation of an artificial insemination (AI) program. At the same time, low-cost production and/or the ability to produce a higher valued product are essential for economic success in the cow-calf industry. Previous research has examined the costs of...

Automatic milking systems (AMS) offer relief from the demanding routine of milking. Although many AMS are in use in Europe and a few are used in the United States, the potential benefit for American farms is uncertain. A farm-simulation model was used to determine the long-term, whole-farm effect of implementing AMS on farm sizes of 30 to 270 cows. Highest farm net return to management and unpa...

the objective of this study was to assess the discounted genetic expressions (dges) for different categories of animal traits as regards holstein cattle of iran. using discounted gene-flow principles, dges per calf born were estimated for self replacing females and also for their sires. in the situation for sires of self replacing females, relative gdes per cow per year for annual cow traits, t...

Infertility has been linked to numerous factors in high producing dairy cattle in the last decades. The detection of estrus continues to present difficulties and, although progress has been made in regards to estrus synchronization and artificial insemination, the reproductive performance of dairy cows has not improved substantially. Moreover, in warm countries, summer heat stress is a major fa...

Fertility, represented by calving interval, has been included in the genetic evaluation of Icelandic cattle since 1993. In spite this an unfavourable trend is seen and, recent implementation test-day models for milk production changed premise using interval to represent fertility. The aim study was estimate parameters and trends different female fertility traits dairy suggest new evaluation. In...

Involuntary culling (IC) is where a cow is disposed of due to injury, poor health or infertility. The main reasons for IC are infertility, mastitis and lameness. These reasons have differing age profiles in when they affect cows, cost variable amounts to treat and have an effect on the value of the cow at market. They also reduce cow welfare in different ways. These factors influence the econom...