Fabio De Rensis

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Summer heat stress is a main factor related to low conception rate in high producing dairy herds in warm areas worldwide. We assessed the impact of several climate variables on conception rate in high producing dairy cows in northeastern Spain by examining 10,964 inseminations. The temperature-humidity index (THI) was compared with maximum temperature in(More)
The aim of the present study was to establish whether temperature-humidity index values, as a measure of heat comfort, from Days 1 to 40 of gestation could be associated with the pregnancy loss rate in high producing dairy cows. Data from 1391 pregnancies were recorded. Pregnancy was diagnosed by transrectal ultrasonography between Days 34 and 45, and again(More)
In dairy cows inseminated during the hot months of the year, there is a decrease in fertility. Different factors contribute to this situation; the most important are a consequence of increased temperature and humidity that result in a decreased expression of overt estrus and a reduction in appetite and dry matter intake. Heat stress reduces the degree of(More)
This study was designed to assess the effects of human chorionic gonadotrophin (hCG), given within a timed artificial insemination program, on plasma progesterone concentrations and subsequent fertility in lactating dairy cows during the warm and cold seasons of the year. Cows were treated intramuscularly with GnRH-agonist (Day 0) and PGF(2alpha) (Day 7)(More)
The aim of this study was to test the effect of progesterone supplementation to Ovsynch protocol in cyclic and non-cyclic Mediterranean Italian buffaloes on conception rate after fixed time artificial insemination. From 169 pluriparous buffaloes, 2 groups were identified and subjected to: (1) Ovsynch protocol (OV; n=83) and (2) Ovsynch protocol with the(More)
It was hypothesized that gonadotropin-releasing hormone (GnRH) treatment at the time of insemination and 12 days later increases conception rates. The aim of the present study was to evaluate the effects of GnRH treatment at the time of insemination or at the time of insemination and 12 days later on reproductive performance during the warm season in high(More)
Heat stress has consequences on both the physiology and reproductive performance of cows, but the most dramatic effect for dairy producers is the decrease produced in fertility. The effects of heat stress on fertility include an increased number of days open, reduced conception rate, and larger number of cows suffering different types of anestrus. Once(More)
Mastitis-induced ovarian abnormalities were studied in a field trial. At 1-3 day after calving, > or = 2 parity cows not affected with chronic recurrent mastitis and yielding < 400,000/ml somatic cell count (SCC) individual milk in the previous lactation, were enrolled in the study. Thereafter milk samples were collected three times weekly for 95-100 day(More)
The principal aim of this study was to investigate the involvement of an opioidergic mechanism in the development of suckling-induced inhibition of LH secretion during early lactation in the sow. A preliminary experiment suggested that 2 mg/kg naloxone given as a single bolus injection was above the threshold for antagonism of endogenous opioid activity in(More)
Equine chorionic gonadotropin (eCG) is a member of the glycoprotein family of hormones along with LH, FSH and thyroid-stimulating hormone. In non-equid species, eCG shows high LH- and FSH-like activities and has a high affinity for both FSH and LH receptors in the ovaries. On the granulosa and thecal cells of the follicle, eCG has long-lasting LH- and(More)