Effects of Recombinant Bovine Somatotropin on Nutritional Status and Liver Function of Lactating Dairy Cows

Abstract

Twenty-four high producing, multiparous Holstein cows were utilized to evaluate effects of long-term administration of sustained-release rbST on blood pH, gases, buffer capacity, circulating metabolites and hormones, and on liver lipid content and functions during lactation. Treatment, commencing 98 to 112 d postpartum and continued until d 305, consisted of a subcutaneous injection of a placebo or 350 mg of rbST every 14 d. Milk and 3.5% FCM were increased significantly by rbST, but milk fat and protein content, feed intake, energy balance, corrected feed efficiency for milk production, and body condition scores were unaffected. Somatotropin decreased blood pH and buffer capacity by decreasing bicarbonate without affecting blood partial pressures of oxygen or carbon dioxide. Concentration of plasma albumin was decreased and nonesterified fatty acids, glucose, insulin, rbST and insulin-like growth factor-I were increased by treatment. Total plasma proteins and cortisol, hemoglobin, and hematocrit were unaffected. Liver DM, total lipid and triacylglycerol contents, and plasma 3-hydroxybutyrate and glutamic oxalacetic transaminase were not affected by rbST, but the percentage of triacylglycerol in total lipids was increased. Results of this experiment suggest that rbST exhibited lipolytic and diabetogenic activities in lactating dairy cows in vivo and that these effects might be important for the increase in nutrient partitioning toward the mammary gland elicited by rbST.

A review of bovine growth hormone

“…2; Elsasser et al 1989). However, this natural uncoupling of the GH-IGF-I axis has not been observed when rbGH is administered to lactating cows in negative energy balance (Gallo 1989;Gallo and Block 1990a (Zapf et al 1986). This would encourage glucose sparing by peripheral tissues and increase the availability of glucose for milk production by the mammary gland (Fig.…”

“…This would encourage glucose sparing by peripheral tissues and increase the availability of glucose for milk production by the mammary gland (Fig. 3) Gallo and Block 1990a). Growing heifers show lesser insulin resistance and lower milk yield responses to rbGH than multiparous cows (Chilliard 1988) (Gallo 1989;Gallo and Block 1990a) (Fig.…”

“…3) Gallo and Block 1990a). Growing heifers show lesser insulin resistance and lower milk yield responses to rbGH than multiparous cows (Chilliard 1988) (Gallo 1989;Gallo and Block 1990a) (Fig. 3), it also appears to allow overall adaptation of metabolism such that the incidence of ketosis and liver disease does not increase (reviewed by McBride et al 1988;Burton and McBride 1989;Chilliard 1989 Elvinger et al 1988;Cleale et al 1989;Hansen et al 1989;McDaniel et al 1989;Burton et al 1990b;Gibson et al 1990), increased number of services per conception (by 0.5-1), and a lower conception rate (by 5-10%) in rbGHtreated versus control cows Huber et al 1988;L6onard et al 1990).…”

Enfriamiento al inicio de verano para mitigar el estrés por calor en vacas Holstein del noroeste de México

“…It is important to mention that cows from this study received a subcutaneous application of bovine somatotropin (STB) as part of the herd management. The STB is a synthetic hormone with similar function to GH in bovine cattle, and its exogenous application is a potential enhancer of heat load in lactating cows under heat stress (13,30,31) , as well as blood concentrations of IGF1 (32)(33)(34)(35) . Therefore, administration of STB in this study could induce a direct effect on IGF1 levels, and consequently on PRL levels.…”

“…Vale la pena señalar que las vacas de este estudio recibían la aplicación de un producto comercial como manejo habitual a base de somatotropina bovina (STB). La STB es una hormona sintética cuya función es similar a la GH en el bovino y su administración exógena incrementa potencialmente la carga de calor en ganado lactante bajo estrés calórico (13,30,31) , así como también la concentración de IGF1 en sangre (32,33,34,35) . Por lo tanto, la administración de STB en este trabajo pudo inducir un efecto directo sobre los niveles de IGF1 y consecuentemente en los de PRL.…”