Pectic acid effects on prolactin secretion in GH3/B6 rat pituitary cell line

Background: Pectic acid extracted from plants increases the secretion of prolactin (PRL) when injected intravenously into ewes or fed to rats. Fragments of ewe hypophysis and lactating rabbit mammary gland incubated in vitro in the presence of pectic acid secreted more PRL and caseins compared to the controls. However, it is not known whether pectic acid directly stimulates PRL secretion in pituitary or interference of factors from hypophysis is required for this process. Methods: GH3/B6 cells, a clonal strain of rat pituitary, were cultured and incubated with pectic acid (2.5-100 mug/mL). The integrity of cells was examined under pectic acid treatment microscopically. Controls or pectic acid treated cells were assayed for their ability to produce PRL. The PRL was assayed by Western-blotting and Radioimmunoassay. Results: pectic acid did not have any significant effect on the viability of cells. After being incubated with pectic acid, the cells started to become circular and protuberant shape. The maximum stimulation and PRL secretion occurred at 100 mug/mL concentration within 30 min of incubation with pectic acid. Conclusion: pectic acid could stimulate the release of PRL in GH3/B6 cells in the short-term incubation. This result suggested that pectic acid is a non-toxic agent that could directly stimulate PRL secretion in pituitary cells without any interference of hypophysis.     

A case-control study to identify farm factors affecting fertility of dairy herds: multivariate description of factors

Objectives To determine whether a multivariate model could be developed to describe farm factors affecting fertility of dairy herd and to examine the factors that determined better reproductive performance on dairy farms in New South Wales.
Procedure We examined the results of a survey of breeding practices, mating policies, recording systems, timing of mating, heat detection, treatment of metritis and manager demographics of dairy farms using Principal components analysis, logistic regression and the sign test.
Results Eight principal components for heat detection computed using Principal component analyses were included in the multivariate model to reflect primary and secondary heat detection signs used in the breeding decisions of managers. A final model identified three variables: optimum number of days to first service, number of people detecting heats, and age of manager which significantly influenced the risk of being in the high or low reproductive performance groups. A failure to breed at an appropriate time after calving and having more people responsible for heat detection was associated with herds with a prolonged intercalving interval. While the model provided a good fit for the data, it was not highly discriminatory. Examination of 83 management practices affecting fertility using the sign test (P = 0.01) indicated that managers of herds with good reproductive performance employed better management and breeding practices more often than managers of herds with poor reproductive performance.
Conclusions Mating cows sooner after calving and using fewer people to detect oestrus should reduce calving to conception intervals. Veterinarians investigating herd reproductive performance should consider the potential for a number of subtle failures of management to significantly impair fertility rather than limit investigations to a few factors.