Effects of phorbol myristate acetate (PMA), dibutyryl cyclic AMP (dbcAMP), 6-dimethylaminopurine (6-DMAP), okadaic acid (OA), cycloheximide (CHX), actinomycin D (AcD) and tunicamycin (TuM) on plasminogen activator (PA) activity and maturation rate in bovine and porcine oocyte-cumulus cell complexes (BOCC and POCC, respectively) in vitro were determined. Plasminogen activator activity was measured by SDS-PAGE, casein-agar zymography and densitometry. Three plasmingen-dependent lytic zones (92-95, 71-73 and 49-51 kD) and one PA inhibitor (52 kD) were observed in BOCC. Immunoprecipitation and amiloride sensitivity suggested that the 49-51 kD protease is a urokinase type PA (uPA), the 71-73 and 92-95 kD proteases are a tissue type PA (tPA) and tPA-PAI complex, respectively, and the PAI is PAI-1. In POCC, two plasminogen activators (71-78 and 93-96 KD) were observed. Lack of amiloride sensitivity suggested that the 71 -78 kD band is a tPA and the 93-96 kD band is possibly a tPA-PAI complex. Increasing dbcAMP in the culture medium increased activity in both BOCC and POCC in dose-dependent fashion (P<0.05). In BOCC cultured with PMA, total PA activity increased, however high concentrations of PMA (10 and 100 ng/ml) decreased tPA activity in matured POCC. Plasminogen activator activity decreased in 6-DMAP, actinomycin D and cycloheximide and oocyte maturation was also inhibited in these treatments. When POCC were treated with 25 nM OA, uPA activity was observed. Plasminogen activator activity increased in either BOCC or POCC treated with up to 25 nM OA, however PA activity decreased at concentrations greater than 75 nM (P<0.05). Incubation of BOCC with tunicamycin reduced the molecular mass of tPA and tPA-PAI complex and PAI-1 by 5-10%, however PA activity was not inhibited. These data suggest that BOCC matured in vitro produce uPA, tPA and PAI-1 however POCC produce only tPA and PAI. The production of PA and PAI by either BOCC or POCC is associated with oocyte maturation and influenced by stimulators of the protein kinase A and C, modulators of intracellular phosphorylation and metabolic inhibitors. / Graduation date: 1993

This descriptive research was undertaken to investigate the preferred channels of communication used in the adoption of livestock production practices by ranchers in the northeastern Mexican state of Nuevo Le??n. The study builds on previous research by Freund (1999). Freund??s study concluded that ranchers in Nuevo Le??n preferred the Uni??n Ganadera as their primary source. However, the producers indicated some communication preferences that resulted in the Uni??n adjusting some of their efforts to reach out to their membership. This study was designed to revisit those livestock producers to investigate what changes had occurred in their preferences for communication since the Freund (1999) study. This research was conducted in the state of Nuevo Le??n, Mexico. The methodology used was a survey employing a questionnaire to collect data. The convenience sample consisted of 273 active members of the Uni??n Ganadera Regional de Nuevo Le??n (UGRNL) who attended regularly scheduled association functions. A principal objective of the research was to describe the communication infrastructure used in the state of Nuevo Le??n by UGRNL livestock producers. Another objective of the research was to describe preferred formal and informal channels of communication that livestock producers use to get information about ranching practices. Yet another objective was to describe what UGRNL livestock producers use as primary sources of information when choosing to adopt or reject agricultural practices, as well as investigating what secondary and feedback channels they prefer. Another objective was to determine which husbandry practices UGRNL livestock producers want more information about. Finally, an emphasis of the study was on what communication channels smaller stakeholders prefer, because the Uni??n wants to use that information to improve its diffusion of technology to that particular group of producers.

The purpose of this study was to assess the perceptions of Master Livestock Volunteer program participants regarding the effectiveness of the program, their role in the county 4-H volunteer program, and the role of various stakeholders in livestock project decision making. A census was attempted of the 242 possible participants. Using recommendations from Dillman (2000), master volunteers were contacted by email if available and via mailed questionnaire. This process yielded a 38% response rate. Follow-up methods increased the response rate to 52.4%. The volunteers indicated the programs was of high importance and effective. Findings included that volunteers perceived their most influence came in the selection of feeds. The educator role was the one most involved in the decision making process of the livestock projects, followed by the manager role, leader role, and various servant-type leadership roles. Volunteers ranked stakeholders' influence on livestock project decisions, with the youth and the parents as most influential followed by the CEA, the volunteer, and the breeder. The average participant reported nine years of overall volunteer service and two years of service as a Master Livestock Volunteer. Participants in this study were between 38 and 47 years of age.

Thesis (MSc (Production Animal Studies, Veterinary Science))--University of Pretoria, 2008. / Includes bibliographical references. Also available in print format.

The role of expectations theory and risk perception is examined in relation to the structure of store livestock markets in England and Wales. Economic and biological features of store production are identified in the beef, dairy, pigs and sheep sectors. The axiomatic base of risk theory is examined and the Expected Utility approach of defining risk is adopted. Allied to the analysis of risk is the role of expectations in store markets. Two major expectations hypotheses are employed which act as a second, and parallel, research investigation to risk in the store markets: Adaptive and Rational Expectations are chosen. The assumptions and modelling approaches that underlie the analysis are outlinedo This then provides a framework in which the influences of risk and expectations are examined. An ex post analysis of grazing risk is undertaken. Farmers typically underutilise grazing resources, possibly as a result of the greater risks involved in feeding ruminant stock in this way. It is shown that grassland production, on average, can be intensified without incurring additional risk in terms of more variable output. The temporal structure of store livestock demand is then investigated on ex ante grounds with subjective risk defined on the basis of the Adaptive Expectations rule. Significant risk responses were found in the store steer, heifer and pig sectors. The demand analysis is then generalised to a full simultaneous and recursive model employing the Rational Expectations hypothesis, The implications of the solution procedure are outlined and the results indicate that risk perception associated with store demand in the pigs market and both store supply and demand in the sheep market are important features of trading. The results of using two different expectations models are then compared. General conclusions are drawn and the overall influence of risk in the store markets is assessed.

The human-animal relationship in agriculture has been shown to be an influential factor affecting farm animal behaviour, welfare and productivity. It has been demonstrated that stockperson behaviour is related to animal fear and productivity and stockperson attitudes have been found to be strong predictors of stockperson behaviour. However, other job-related human factors may also be influenced by attitudes, thus affecting stockperson work performance. Inter-relationships between stockperson attitudes and behaviours and other job-related human factors were determined. The effects of human behaviour on the behavioural response of pigs towards humans was further investigated and the role of training to modify job-related factors, such as technical knowledge was examined. Stockperson behaviour was shown to influence the behavioural response of pigs towards humans and behavioural responses of pigs towards humans could be conditioned within 4 weeks of regular handling. Negative behaviour by the stockperson was shown to be the most aversive human-animal interaction, while injection treatments were moderately aversive in comparison. The negative effects of human behaviour and husbandry procedures were not found to be alleviated by positive handling or environmental enrichment. The behavioural response of pigs towards humans was found to be influenced by social learning processes and stimulus generalisation of the behavioural response of pigs to humans was found to be unaffected by location. Other job-related human factors, such as technical knowledge, empathy and job satisfaction were positively related to stockperson attitudes and behaviour. Due to established sequential relationships between stockperson attitudes and behaviour and pig behaviour and productivity, this was viewed as indicative of the effect of these job-related variables on pig behaviour and productivity.

No description available.

Thesis (doctoral)--Universität Breslau.

Thesis (Ph. D.)--California State University, Long Beach, 1998. / Includes bibliographical references (leaves 123-141).

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains ix, 150 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 116-149).