No abstract

Estradiol-17 beta (E2 beta) produces uterine and systemic vasodilation in nonpregnant ewes without altering mean arterial pressure (MAP). Mechanisms responsible for maintaining MAP and thus uterine blood flow (UBF) may include activation of the renin-angiotensin and/or adrenergic systems. We therefore investigated the effects of systemic blockade of angiotensin II (ANG II) and/or alpha-adrenergic receptors in nonpregnant, castrated ewes, using saralasin (Sar) and/or phentolamine (Phen) in the presence or absence of intravenous E2 beta (1.0 microgram/kg). In nonestrogenized ewes neither antagonist alone had substantial cardiovascular effects; however, Sar + Phen decreased systemic vascular resistance (SVR) 20 +/- 7.4% (SE) and increased heart rate (HR) 50 +/- 19% (P < 0.01); MAP and UBF were unaffected. Following E2 beta treatment SVR fell 17 +/- 2.4% (P < 0.01), UBF increased more than fourfold, and MAP was unchanged. Compared with E2 beta alone, Phen + E2 beta decreased SVR 42 +/- 4.7%, and MAP fell 11 +/- 1.8% (P < 0.05) despite 40-50% increases in HR and cardiac output (P < 0.05). Responses to Sar + E2 beta were similar to E2 beta alone, except for a fall in MAP, whereas responses to Sar + Phen + E2 beta resembled those of Phen + E2 beta. E2 beta-induced uterine vasodilation was unaltered by Sar and/or Phen. During E2 beta-induced vasodilation, MAP is maintained by enhanced activation of the alpha-adrenergic and renin-angiotensin systems; however, uterine vascular responses to E2 beta are independent of both systems and perfusion pressure.

The Dairy Challenge contest allows undergraduate students to apply knowledge gained in the classroom in an evaluation of the management practices of commercial dairy farms. University faculty partnered with industry representatives to develop the competition. Participants in the Dairy Challenge do the following: 1) critically evaluate dairy herd management practices and make recommendations for improvements; 2) visit local dairy farms and gain knowledge of different farms' management practices; 3) meet and interact with potential employers from the dairy industry during the contest; 4) evaluate herd records and utilize knowledge of dairy herd management software and computer presentation tools; 5) test their speaking, presentation, and problem-solving skills; and 6) work as a team to build consensus and tag-team speaking formats. Teams of four undergraduate students critically evaluate a commercial dairy farm using herd records, a description of farm operations, and tour of the farm facilities. The farmer answers questions pertaining to management of the farm in a group interview with all teams and in a separate interview with each individual team. Teams give a 20-min presentation that is scored on the description and assessment of the management practices and recommendations for improvements in management and facilities. Additionally, scoring is based on apparent level of preparation, speaking, presentation skills, and responses to judges' questions. The judges are university specialists and dairy industry professionals. This capstone experience allows students to interact with dairy farmers and representatives from the dairy industry and expands their knowledge and skills gained during their academic career.

Our objective was to determine effects of feeding prepubertal heifers (n=16/trt) for rapid gains for different lengths of time (0, 3, 6, 12 wk) on body and mammary growth. Increasing time on the high diet increased mass of carcass and extraparenchymal mammary fat but did not alter mammary parenchyma weight. Increasing time on the high diet decreased mass of mammary parenchyma per kg carcass in a linear fashion. Although mass of parenchyma was not decreased by feeding the high diet for only 3 or 6 wk, changes were consistent with impaired growth seen with 12 wk of the high diet.