the aim followed in the present research was to study the effects of reduction in dietary crude protein on milk production and on blood components in lactating holstein dairy cows when in heat stress. a number of 63 holstein dairy cows (71 ± 16.5 dim) were chosen to be made use of in a randomized complete block design. the cows were randomly assigned to any one of the three experimental rations...

The objectives of the present study were to determine the effects of resynchronization with GnRH on Day 21 after artificial insemination (AI) on pregnancy rate and losses of pregnancy in lactating dairy cows. Holstein cows (n=585) on two dairy farms were assigned to one of two treatments in a randomized complete block design. On Day 21 after a pre-enrollment AI, animals assigned to the resynchr...

Iodine (I) is an essential element for efficient dairy cow metabolism. Iodine status is however not well known on farms. The objective was to measure milk and plasma I concentrations in a selected group of commercial dairy herds in central Iranian province of Isfahan. During summer of 1999 and winter of 2000, 11 dairy farms were randomly chosen and a minimum of 10 cows were sampled from each fa...

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...

BACKGROUND Gyr cows are well adapted to tropical conditions, resistant to some tropical diseases and have satisfactory milk production. However, Gyr dairy herds have a high prevalence of subclinical mastitis, which negatively affects their milk yield and composition. The objectives of this study were (i) to evaluate the effects of seasonality, mammary quarter location (rear x front), mastitis-c...

Two experiments were conducted to evaluate dry matter intake (DMI), milk yield, and milk composition from feeding rations that contained different sources of genetically modified whole cottonseed to Argentinean Holstein dairy cows. Twenty-four lactating multiparous Argentinean Holstein dairy cows were used in 2 experiments with a replicated 4 x 4 Latin square design, with cows averaging 565 kg ...

Female ruminants are susceptible to spontaneous ketosis arising at times of high productive demand. The dairy cow is most susceptible during the first 7 weeks of lactation, whereas the ewe is susceptible, particularly when multifoetate, during the last month of pregnancy. The disorder is characterized by signs of carbohydrate insufficiency and adipose-tissue mobilization. Those of carbohydrate ...

Manure management plans require knowing the amount of manure produced, collected, and available for land-spreading. Whereas much information is available to calculate manure production, little is known about the types and amounts of manure actually collected on typical dairy farms. This study of 54 representative Wisconsin dairy farms showed significant regional, housing, and herd size differen...

Heat stress causes infertility in farm animals and represents a major source of economic loss. In response to heat stress, managers can attempt a variety of approaches to improve reproduction. These approaches usually involve modifying the environment (i.e., attempting to cool cows during reproduction), modifying the genetics of the animal (i.e., breeding to heat tolerant breeds) or intensifyin...

The objective of the experiment was to determine the effects of fat supplementation on embryo quality of dairy cows and the subsequent success of embryo transfer into recipient heifers fed the same sources of fat. A total of 30 lactating Holstein cows were allotted on d 18 postpartum to 2 groups of 15 donor cows blocked for similar calving dates. Total mixed diets based on silage and fat supple...