One critical determinant of fertility is the establishment and maintenance of pregnancy after insemination or embryo transfer. Pregnancy success is low in lactating dairy cows. Reduced fertility of the dairy female is only expressed in the lactational state but the magnitude of depression of fertility is not related to milk yield. Pregnancy failure occurs throughout gestation with the greatest ...

As the number of horses is steadily increasing in Cantabrian less-favoured areas, mostly occupied by nutritionally poor heathland communities, the objective of this research was to study and compare diet selection and performance of crossbred horses and beef cattle (Asturiana de los Valles breed) grazing these areas during the summer. A total of 20 cows (seven lactating their calves and thirtee...

performance, digestibility of nutrients, microbial nitrogen flow (mnf) and nitrogen efficiency (ne) inearly lactating holstein cows were investigated by diet supplementation with sodium caseinate (cn).multiparous lactating holstein cows (n = 15) with an average body weight of 638 kg and 21 days in milkwere assigned to a completely randomized design (five cows per treatment) and fed a basal diet...

Female fertility is essential to any beef breeding program. However, little genetic gain has been made due long generation intervals and low levels of phenotyping. Days calving (DC) a trait that may provide lead an increased weaning rate. Genetic parameters correlations were estimated compared for DC across multiple joinings (first, second third+) lactation status (lactating non-lactating) trop...

Increased milk somatic cell counts (SCC) are used as an indicator for bovine mastitis. During mastitis, polymorphonuclear leukocytes (PMN) become the predominant cell type. Shortly after parturition, the severity of mastitis is increased and several PMN functions are downregulated. Apoptotic and necrotic processes of PMN could influence SCC and PMN functions. In this study, the percentages of a...

The objective of this study was to describe the incidence of papillomatous digital dermatitis in the US (including regional and herd size patterns) and to evaluate specific herd-level management factors associated with high incidence of digital dermatitis in US dairy herds. The study design was a population-based cross-sectional survey. US dairy operations with at least 30 cows in 20 states, re...

More than a decade of observations of dairy operations in Hawai‘i suggested that there were more black cows in the local dairy herds than white cows. Hence, the objective of the study was to investigate if hair coat color affected productive life of Holstein cows in the sub-tropics. Two large herds within 2,000 meters of each other in the Waianae Coast district were used. Lactating cows were cl...

the precision and accuracy of national research council (nrc 2001) vs. cornell pennsylvania miner (cpm) softwares were evaluated. sixteen lactating dairy cows (8 in second lactation and 8 in third, with days in milk of 55 ± 31, body live weight = 641 ± 53 kg, milk yield =31.2 ± 2.5 kg/day), were assigned to individual pens in a randomized complete block design, with two blocks of two ration tre...

One strategy for improving fertility in cattle is mid-cycle administration of GnRH to increase progesterone secretion and delay luteolysis. This strategy might be especially useful during hot weather because heat stress increases uterine prostaglandin release and reduces development of the elongating embryo. A series of experiments was conducted to test the efficacy of GnRH for increasing ferti...

An electronic probe with parallel stainless steel electrodes was designed to measure changes in electrical resistance in the anterior vagina associated with increased cervical mucus secretion at estrus. Three groups of Holsteins were probed, and a sample of residual milk after milking was taken for progesterone assay every 2nd day for 28 to 40 days. Group I consisted of 29 cycling virgin heifer...