Responses to abomasal infusions of casein plus methionine in lactating ewes fed fresh pasture

Abstract

Twin-bearing Romney ewes were fed fresh pasture of 80% organic matter digestibility (11.4 MJ ME per kg OM) and 3.5% N ad libitum for 6 weeks during early lactation. Eight of the 18 ewes were given a daily abomasal infusion of 95 g sodium caseinate and 2 g I-methionine. Voluntary pasture OM intake did not significantly differ between control and infused ewes. The infusions had no effect on milk secretion at peak lactation (week I), but the decline in net rates of protein and fat secretion as lactation progressed was less for infused than for control ewes. Wool production rates were low, and were unaffected by the infusion treatment. The quantity of amino acid N estimated to have been absorbed from the small intestine was respectively 85% and 110% of that required to sustain the levels of milk and wool production that were actually recorded in control and infused ewes. The absence of a difference in milk production between the two groups of ewes at peak lactation may have been due to greater mobilisation of body protein reserves by the control ewes. The higher plasma concentration of growth hormone observed in the infused ewes was probably implicated in their improved lactation persistency.

The effects of abomasal casein infusions in growing beef steers on portal and hepatic flux of pancreatic hormones and arterial concentrations of somatomedin-C.

“…In response to postruminal casein infusions, jugular vein plasma somatostatin concentrations were decreased in nonlactating sheep (Barry et al, 1982) and increased in lactating ewes (Barry, 1980). The portal and hepatic SLI flux measurements (Table 2) were highIy variable, as noted previously in beef steers (Reynolds et al, 1986) and in dairy cows .…”

Effects of Mild Heat Exposure and Suppression of Prolactin Secretion on Gastro-intestinal Tract Function and Temperature Regulation in Sheep

“…Heat exposure did not cause an increase in prolactin concentrations beyond that already achieved by continuous lighting. The observed concentrations were within the range (100-280 p.g/l) that has been reported for lactating ewes (Barry 1980;Gow et al 1983).…”

Influence of ruminal or abomasal starch hydrolysate infusion on pancreatic exocrine secretion and blood glucose and insulin concentrations in steers.

“…Few studies in ruminants have examined changes in somatostatin concentration with postruminal nutrient infusion. Jugular vein plasma somatostatin concentrations were decreased in nonlactating ewes (Barry et al, 1982) and increased in lactating ewes (Barry, 1980), and no change was reported in beef steers (Guerino et al, 1991) infused postruminally with casein. However, to our knowledge no studies have measured somatostatin concentration with carbohydrate feeding or infusion in ruminants.…”