Influence of plane of nutrition on portal blood flow and the metabolic clearance rate of progesterone in ovariectomized gilts

Abstract

S U M M A R YThe effects of plane of nutrition on blood flow in the portal vein (PBF) and on the rate of clearance of progesterone from the circulation (MCR) were measured for 14 or 24 h in six ovariectomized gilts given 1 or 3 kg of food per day. On a body weight basis, PBF was significantly increased by the increase in food intake from a mean for all gilts of 14-9 ml/kg.min (1-34 litres/min) on 1 kg to 21 -6 ml/kg. min (1 -96 litres/min) on 3 kg, a mean increase of 45 %. Metabolic clearance of progesterone was increased by a similar percentage, 4 7 1 % , from 410 ml/kg.min (3-70 litres/min) to 60-3 ml/kg.min (5-67 litres/min) by the increase in food intake. Both MCR and PBF were lowest between 04.00 and 06.00 h, increasing after each feed except that when 3 kg/day was fed the MCR remained high throughout the period between meals. In two gilts, blood flow in both the portal vein and hepatic artery (HAF) was measured. The mean PBF and HAF for each pig were 40-6 and 5-8, and 32-4 and 35 ml/kg, min respectively. HAF was 11-2% of total hepatic blood flow.

An increased feed intake during early pregnancy improves sow body weight recovery and increases litter size in young sows1

“…For multiparous sows, no uegative effects of an increased feeding level during early pregnancy have been reported (e.g., Varley aud Prime, 1993, d 1 to 25;Virolainen et al, 2005). Negative effects of an increased feeding level on embryonic survival in gilts have been related to reduced plasma progesterone concentrations in animals on an increased feeding level (Ashworth, 1991;Jindal et al, 1996;van den Brand et al, 2000;Virolaiueu et al, 2005) because of increased progesteroue clearance in the liver (Prime and Symonds, 1993). A sufficiently iucreased progesterone concentration is necessary for synchronous uterine and embryonic developmeut during early pregnancy (Pope, 1988;Ashworth, 1992).…”

Feed restriction in cyclic gilts: gonadotrophin-independent effects on follicular growth

“…The level of feeding slightly altered progesterone levels, but not significantly. Previous findings have demonstrated higher progesterone level in feed-restricted sows, either at luteolysis [13] or during luteal development after ovulation [25], possibly due to a decreased metabolic clearance [22].…”

Physiological and practical effects of progesterone on reproduction in dairy cattle

“…For example, if liver blood flow increased from 1000 to 2000 l/h then circulating P4 concentrations will decrease to 50% even though P4 production and P4 metabolizing enzymes have not changed (Sangsritavong et al, 2002;Wiltbank et al, 2006 and. The role of feed intake in regulating liver blood flow, P4 metabolism, and circulating P4 was initially demonstrated in studies with pigs and sheep (Christenson et al, 1985;Parr et al, 1993;Prime and Symonds, 1993). For example, the studies in sheep showed convincingly that as feed intake increased, there was a clear increase in liver blood flow with a corresponding decrease in circulating P4 (Parr et al, 1993).…”