Is twin pregnancy, calving and pregnancy loss predictable by serum pregnancy-specific protein B (PSPB) concentration 28–35 days after ai in dairy cows?

Double ovulation occurs more frequently in multiparous cows with high milk production than in primiparous cows and the rate of twin pregnancy/calving is increasing worldwide. Diagnosis of twin pregnancy is possible by ultrasound at the time of early pregnancy examination [28–34 days after artificial insemination (AI)]. Pregnancy proteins are also well-known indicators of gestation. The risk of pregnancy loss during the first trimester of gestation for cows carrying twins is three to nine times higher than for cows carrying singletons. Pregnancy-specific protein B (PSPB) is a good indicator not only of pregnancy but also of pregnancy loss. The aims of this study were (a) to collect calving data in some Hungarian Holstein-Friesian herds (n = 7,300) to compare PSPB serum concentrations (measured 29–35 days post insemination) in twin- and singleton-calving cows (Trial 1), and (b) to check the predictive value of PSPB serum concentration for twin pregnancy and pregnancy loss in high-producing Spanish Holstein-Friesian cows (n = 98; Trial 2). Our results showed almost 7% twin calving rate. Although hormonal treatments are commonly believed to be major causes of twin pregnancies, our data do not support this hypothesis. The only exception is the single PGF injection, which significantly increased twin calving. No effect of milk production on the risk of twin pregnancy was found, and twin pregnancy increased with parity. The AI bull, the bull’s sire, the bull’s grandfather and the cow’s father also affected twin calving (P ≤ 0.02). We found much higher frequency of twin calving in cows diagnosed pregnant with higher than 3 ng/ml serum PSPB concentrations at 29–35 days after insemination. In Trial 2, non-significant but well-marked differences were found in PSPB serum concentration between singleton- and twin-pregnant cow samples (2.1 and 2.9 ng/ml) at different bleeding times. Probably the small size of the study population and the effects of milk production on PSPB values may explain this lack of significance

When is a cow in estrus? Clinical and practical aspects.

Good detection of estrus is critically important in dairy husbandry. Incorrect detection of estrus is related to loss of profit due to extended calving intervals, milk loss, veterinary costs, etc. Detection of estrus remains a major problem despites enormous progress in the knowledge of reproductive physiology of the cow and in development of estrus detection aids. To achieve good estrus detection, many factors have to be taken into account. On one hand a cow has to express estrus and on the other hand the farmer has to detect it. Combined action of several hormones causes physiological changes that lead to ovulation and an environment in the uterus that allows sperm to fertilize the egg. Besides these internal actions, a number of external changes can be observed. When using visual observations, time of the day and time spend on observation have a great impact on detection rates. Many devices are available to aid in estrus detection, such as pedometers, mount devices, temperature, and hormone measurements. Expression of estrus can be influenced by many factors. Heritability, number of days postpartum, lactation number, milk production, and health are known to influence estrus expression. Environmental factors like nutrition, season, housing, herd size, etc. also play a role in estrus expression. To evaluate estrus detection, record keeping is very important; a number of formulas can be used to assess detection efficiency. Besides the farmer, the veterinarian and inseminator can play an important role in estrus confirmation and good insemination strategy. In the end, the time of ovulation and the age of the egg at sperm penetration is critical for conception. Therefore, emphasis in research needs to be on the timing of insemination relative to ovulation, and thus on the detection of ovulatio