Somatomedin C in dairy cows related to energy and protein supply and to milk production

Abstract

Somatomedin C and other hormones, as well as blood metabolites, were measured during the dry period and during lactation in dairy cows, given different amounts of energy and protein, to study metabolic and endocrine adaptations. Somatomedin C, specifically measured by radioimmunoassay after separation from its binding protein, did not exhibit typical diurnal variations, in contrast to somatotropin and insulin, which increased particularly after concentrate intake. Somatomedin C markedly decreased at parturition and reached lowest values around the peak of lactation, while levels of somatotropin, nonesterified fatty acids and ketone bodies were high and those of glucose, insulin, thyroxine and triiodothyronine were low. Thereafter somatomedin C values slowly increased up to the 12th week of lactation and remained elevated. Low energy and protein balances were characterized by particularly low somatomedin C concentrations. An additional protein deficit at peak lactation, when cows were already provided with low amounts of energy, did not further decrease somatomedin C levels. However, when high amounts of energy were given in the form of starch or crystalline fat, somatomedin C increased. Overall, there was a positive correlation of somatomedin C primarily with energy, but also with protein balances and a negative correlation with milk yield. Conversely, somatotropin increased markedly after parturition and was positively correlated with milk production and negatively with protein and energy balances. Thus, somatomedin C levels were paradoxically low in the presence of high circulating somatotropin. Insulin most closely paralleled somatomedin C levels. Therefore the anabolic state of metabolism at the end of pregnancy was characterized by high somatomedin C and insulin and relatively low somatotropin, whereas the catabolic state of early lactation was characterized by high somatotropin, low somatomedin C, insulin and thyroid hormones.

Endocrine characteristics of late pregnant hyperketonaemic ewes and their reproductive performance following the induction of ovarian cyclicity out of the breeding season

“…BHB, NEFA), and the levels of most of the hormones regulating energy homeostasis (e.g. insulin, IGF-1, T 4 and T 3 ) were similar to those determined in feedrestricted Chelikani et al, 2004) or high-producing (Wensing et al, 1997) postpartum dairy cows, and reflected NEB-related tendencies (Ronge et al, 1988;Chilliard et al, 1998;Veerkamp et al, 2003). In accordance with the experiences of Henze et al (1998), these findings reinforce the supposed role of lower than normal secretory capacity of pancreatic β-cells and/or the low level of insulin in plasma, as primary endocrine factors in the pathogenesis of pregnancy toxaemia.…”

“…In accordance with the experiences of Henze et al (1998), these findings reinforce the supposed role of lower than normal secretory capacity of pancreatic β-cells and/or the low level of insulin in plasma, as primary endocrine factors in the pathogenesis of pregnancy toxaemia. As observed in cattle (Ronge et al, 1988;Diskin et al, 2003), the decreased concentration of IGF-1 may reflect the NEB also in late pregnant hyperketonaemic ewes. In response to feed deprivation low insulin and IGF-1 levels were seen also in pregnant beef cows (Lents et al, 2005) and postpartum dairy cows Chelikani et al, 2004).…”

“…Its effect is complemented by depressed circulating concentrations of insulin-like growth factor-1 (IGF-1), thyroxine (T 4 ) and 3,3′,5-triiodothyronine (T 3 ), whereas the plasma level of the inactivated thyroid hormone formation (3,3′,5′-triiodothyronine or reverse-triiodothyronine, rT 3 ) increases (Huszenicza et al, 2006). These endocrine alterations reflect the current severity of NEB (Pethes et al, 1985;Ronge et al, 1988), and have a crucial role in the pathomechanism of NEB/ketosis-related ovarian malfunctions in dairy cattle (Butler, 2003;Diskin et al, 2003).…”

Metabolic response of early-lactating cows exposed to transport and high altitude grazing conditions

“…This explains reduced thyroid hormone levels during energy deficiency (Kunz et al, 1985;Ronge et al, 1988) but also increased levels at low ambient temperatures, as was found in the case of T 3 by Aceves et al (1987). Considering that ambient temperature was considerably lower at high altitude than at lowland (Christen et al, 1996), the effect of cold exposure on heat production (Sano et al, 1995) obviously exceeded the decrease in heat production expected in the state of deficient energy supply (Ortigues and Vermorel, 1996).…”

Insulin-like growth factor I during growth in bulls

“…We have shown that IGF, levels in cattle barely change during a 24-h period, despite wide variations in feed intake and in the presence of considerable diurnal alterations in metabolism and in other endocrine systems (Ronge et al, 1988).…”