Differences between lactating and non-lactating dairy cows in concentration and secretion rate of insulin

Abstract

1. Four parameters of insulin metabolism were compared in catheterized lactating and non-lactating Friesian x Ayrshire dairy cows. 2. The four parameters, i.e. arterial and portal-venous concentrations of insulin, and pancreatic output and hepatic uptake of insulin, were approx. 2-, 3-, 3- and 5-fold higher respectively in the non-lactating cows than in the lactating cows in the normal fed state. Statistical significance was not achieved for the differences in magnitude in the case of the latter two parameters, however. 3. All four parameters increased significantly about 4-fold when non-lactating cows were infused intravenously with glucose for 48 h at a rate of 4.2 mmol/min. The parameters also increased in the lactating cows during glucose infusion, but the values reached were substantially lower than in the non-lactating cows and the increases were not statistically significant. 4. Arterial insulin concentrations doubled in the non-lactating cows during a 3 h infusion of propionate into a mesenteric vein, but remained unaltered in the lactating cows. 5. Differences in insulin concentration and output between the lactating and non-lactating cows were not consistently related to differences in either glucose concentration or glucose-entry rate. Arterial propionate concentrations were similar in both groups of cows at all times. 6. It is concluded that in the dairy cow, insulin secretion in response to an insulinotropic agent is diminished during lactation.

Responses of North American and New Zealand strains of Holstein–Friesian dairy cattle to homeostatic challenges during early and mid-lactation

“…This observation is likely a reflection of the superior EB and reduced mammary glucose demand at T2 compared to T1. In support of this, pancreatic insulin secretion in response to glucose and propionate infusions is greater in non-lactating cows than in lactating cows (Lomax et al, 1979). Similarly, Sano et al (1993) used a hyperglycemic clamp to demonstrate that the increase in circulating insulin concentrations in response to glucose infusion is reduced in lactating compared to non-lactating cows.…”

Indicadores bioquímicos e hormonais de casos naturais de toxemia da prenhez em ovelhas

“…O estado de hiperglicemia, constatado como achado mais frequente, pode ser explicado pela condição de estresse das ovelhas, constatado pelos elevados índices de cortisol encontrados, que resultam numa gliconeogênese, e que se tornam mais acentuados quando ocorre a morte dos fetos, como ocorrido nas ovelhas em ambos os grupos (Ford et al 1990). Outro fator, que ainda não está bem definido, que pode ser considerado por contribuir com este resultado, seria os valores baixos verificados para insulina e elevados de AGNE, esta condição tem sido postulada como resultado da criação de um ambiente no qual se suporta a minima utilização de glicose pelos tecidos periféricos e seu má-ximo uso pelo útero grávido, ou seja, a sensibilidade dos tecidos periféricos para insulina está reduzida e a mobilização de tecido adiposo para produzir AGNE como fonte alternativa de energia para a ovelha está elevada, esta alteração pode reforçar a hipótese de que ocorra uma insuficiência na regulação hormonal do metabolismo de lipídeos e da glicoestase como causa da TP, durante a sua evolução nas ovelhas (Lomax et al 1979, Pethick et al 1983, Sigurdsson 1991, Peterson et al 1993.…”

Revue bibliographique : Variations quantitatives et métabolisme des lipides dans les tissus adipeux et le foie au cours du cycle gestation-lactation 2e partie : chez la brebis et la vache

“…La Sato, 1977: Bernal-Santos, 1982 fig. 9 Armstrong et Prescott, 1971 ;Patterson et Linzell, 1974 ;Young, 1977 ;Peeters et a/., 1979 ;Thilsted, 1985a (Lindsay, 1971(Lindsay, , 1979Baird et al, 1975Baird et al, , 1980Baird et al, , 1983Lomax et al, 1979 ;Kenna et al, 1981 ;Aiello et al, 1984) et ils sont corrélés au niveau de production laitière (Lomax et .…”