Endocrine Control of Energy Metabolism in the Cow: Comparison of the Levels of Hormones (Prolactin, Growth Hormone, Insulin and Thyroxine) and Metabolites in the Plasma of High- And Low-Yielding Cattle at Various Stages of Lactation

Abstract

To obtain information on the physiological mechanisms controlling the partition of dietary energy between body weight and milk production in lactating cattle, the concentrations of hormones (prolactin, growth hormone, insulin and thyroxine) and metabolites (glucose, non-esterified fatty acids, \g=b\-hydroxybutyric acid and l-lactic acid) in plasma obtained from eight high-yielding and seven low-yielding cows, matched for diet and stage of lactation, were compared. Blood samples were taken via a jugular catheter, throughout four 48 h periods at various times during lactation (days 40, 80, 120 and 180) and also when the animals were dry.The milk yield rose for 7 weeks after parturition, reaching peak values of 24\m=.\8and 10\m=.\1 kg/day in the high-and low-yielding groups respectively. The body weights of the l ow\ x=req-\ yielding animals rose steadily, whereas cows in the high-yielding group lost weight up to week 14 of lactation and thereafter gradually gained weight. No differences were found between the groups in the digestibility of the diets, although analysis of the rumen fluid indicated small differences in the proportions of volatile fatty acids. Milk analysis suggested that the protein content of milk obtained from low-yielding cows was greater than that of milk from high-yielding animals.Throughout lactation, the concentrations of growth hormone (P < 0\m=.\001), non-esterified fatty acids (P < 0\ m=. \ 01) and \g=b\-hydroxybutyric acid (P < 0\ m=. \ 05)were higher in the high-yielding than in the low-yielding group, whereas the concentration of insulin was higher (P < 0\ m=. \ 01) in the low-yielding animals. The level of thyroxine was higher (P < 0\ m=. \ 05) in the low-yielding group when the animals were dry. A comparison of peak lactation (days 40 and 80) with the dry period demonstrated that the concentration of prolactin was higher in both groups hi gh\x=req-\ yielding, P < 0\ m=. \ 01 ; low-yielding, P < 0\m=.\001) when the animals were dry and the concentration of thyroxine in the low-yielding cows was higher (P < 0\ m=. \ 01) when the animals were dry. Significant reductions in the concentrations of growth hormone (P < 0\m=.\001) and non-esterified fatty acids (P < 0\m=.\001) were accompanied by an increase in the concentration of glucose (P < 0\ m=. \ 01) when the high-yielding animals were dry.

Effects of different energy intakes before and after calving on food intake, performance and blood hormones and metabolites in dairy cows

“…The marked elevation of IRI levels at parturition was related to the increase of glucose. Interestingly, IRI levels barely decreased after parturition in group B and remained lowest in group C. Thus, IRI mirrored the degree of energy deficit, which agrees with Hove (1974), Schwalm and Schultz (1976), Hart, Bines, Morant and Ridley (1978) and Blum, Frohli, Moses, Thun, Wanner, Jans and Hart (1983b). It is anticipated that the low insulin concentrations after parturition facilitated fat and protein mobilization, resulting in a reduction of body weight, particularly in the deliberately underfed cows.…”

“…Significantly higher GH levels were measured during the dry period in animals fed energy restricted to requirements compared to those fed ad libitum. Energy deficiency has repeatedly been shown to be accompanied by a rise in GH (Hove and Blom 1973;Hart et al, 1978;Blum, Kunz, Schnyder, Thomson, Vitins, Blom and Bickel, 1979;Blum et al, 1983b). Although GH was higher during lactation than during the dry period, the concentrations were similar in all groups during lactation, despite markedly different energy intakes.…”

Thyroid hormones, blood plasma metabolites and haematological parameters in relationship to milk yield in dairy cows

“…Such negative relationships between T 4 , PBI or T 3 levels and milk yield have been described previously (Cappa and Bertoni, 1971;Vanjonack and Johnson, 1975;Hart et al, 1978a;Walsh, Veseley and Mahadevan, 1980). The relatively low thyroid hormone levels in high-yielding, as compared to low-yielding, cows is surprising in view of reports indicating an enhanced secretion rate of T 4 with increasing milk production (Anderson, 1971), and since the administration of thyroid hormones is well known to stimulate milk production.…”

“…The decrease of glucose levels during the first weeks after parturition may be interpreted as mainly the consequence of the high demand for this substance, primarily for lactose synthesis (Bickerstaffe, Annison and Linzell, 1974). Relatively low glucose levels in high-as compared to low-yielding cows have also been found by Pehrson (1971) and Hart et al (1978a). However, differences were small in all these studies, thus explaining the absence of significant relationships between glucose levels and milk yield, but because Schwalm and Schultz (1976) reported a small positive correlation between plasma glucose levels and milk yield, the situation remains controversial.…”

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

“…Une tendance à la lipomobilisation a toutefois été observée dans certaines expériences de longue durée (Soderholm et al, 1986a, b Emery, 1973 ;Convey, 1974 ;Patterson et Linzell, 1974 ;Bauman, 1976 ;Swan, 1976 ;Coggins et Field, 1978 ;Hart et al, 1978Hart et al, , 1979Miller et al, 1978 ;Cowie et al, 1980 ;Walsh et al, 1980 ;Trenkle, 1981 ;Blum et al, 1982Blum et al, , 1983Blum, 1983, Mc Dowell, 1983Bitman et al, 1984b ;Collier et al, 1984 ;Refsal et al, 1984 ;Aceves et al, 1985 ;Akasha et al, 1985 ;Frohli et Pethes et al, 1985 ;Plaut et al, 1985 ;Thilsted, 1985b ;Bauman et Mc Cutcheon, 1986 ;Gerloff et al, 1986bJ. Les réponses de la sécrétion d'hormone de croissance à la sous-alimentation (revue de Vernon, 1980) ou à la gestation (Koprowski et Tucker, 1973) (Collier et al, 1984). La mobilisation des protéines corporelles (revue de Chilliard et al, 1983) Van den Bergh, 1972 ;Metz et al, 1974 (Little, 1974 ;Rowlands, 1978 ;Treacher, 1978 ;Larnicol et al, 1984).…”