O objetivo deste trabalho foi estudar os efeitos da administração parenteral de vitamina E no desempenho produtivo e na sensibilidade à insulina de cordeiros nascidos de ovelhas suplementadas ou não com vitamina E no 108º dia de gestação. Foram utilizados 28 cordeiros em delineamento de blocos casualizados, considerando o sexo dos cordeiros e tipo de gestação, se única ou gemelar; com planejamento fatorial 2X2, em que foram considerados cordeiros de ovelhas que receberam ou não vitamina E e cordeiros que receberam ou não vitamina E na dosagem de 60 UI/kg PV até 24 horas após o nascimento, distribuindo em quatro grupos: EE: Cordeiros e ovelhas que receberam vitamina E; EC: Cordeiros que receberam veículo oleoso (controle) nascidos de ovelhas que receberam vitamina E; CC: Cordeiros e ovelhas que receberam veículo oleoso; CE: Cordeiros que receberam vitamina E nascidos de ovelhas que receberam veículo oleoso. Para detecção da sensibilidade à insulina, aos 28 dias de vida (T1) os cordeiros foram submetidos ao teste de tolerância à glicose (TTG). Foram determinados aos dois (T0) e aos 28 (T1) dias de vida as atividades de CK, AST, GGT, SOD, GSH-Px; o status antioxidante total (TAS); a habilidade de redução do ferro plasmático (HRFP), as substâncias reativas ao ácido tiobarbitúrico (TBARs); as concentrações de ácido úrico, glicose, ácidos graxos não esterificados (AGNE), betahidroxibutirato (BHB), triglicerídeos, colesterol, cálcio total, cálcio ionizável, proteína total, albumina, ureia, creatinina e a concentração plasmática de vitamina E (alfa-tocoferol). Foram calculados os valores de RQUICKI e de RQUICKI BHB em T0 e em T1. Semanalmente foram acompanhados o peso e o escore de condição corporal dos cordeiros (ECC). Os dados foram analisados utilizando-se o pacote estatístico STATISTICAL ANALYSIS SYSTEM (SAS) e para todos os testes foi adotado o nível de significância de 5%. A administração parenteral de 60 UI/kg de vitamina E em ovelhas no 108o dia de gestação e/ou nas primeiras 24 horas de vida de cordeiros não influenciou as concentrações de cálcio total, proteína total, ureia, albumina, TAS, cortisol, insulina; as concentrações plasmáticas de glicose, colesterol, triglicérides, AGNE, HRFP; as atividades de AST, GGT, GSH-Px e SOD; e os valores de RQUICKI, peso e ECC. Foi observada diminuição da sensibilidade à insulina e concentração de alfa tocoferol no T0 para cordeiros nascidos de ovelhas suplementadas com vitamina E. A suplementação dos cordeiros melhorou o status antioxidante no T0 e a produção de BHB no T1. A suplementação com alfa tocoferol não influenciou no peso vivo e no ECC até a quarta semana de vida do cordeiro. / The objective of this work was to study the effects of parenteral administration of vitamin E on the productive performance and insulin sensitivity of lambs born from ewes supplemented or not with vitamin E on the 108th day of gestation. Twenty-eight lambs received intramuscularly 60 UI/kg BW of vitamin E or oily vehicle until 24 hours after birth and were distributed according to their sex and type of pregnancy (single or twin) into four groups using a 2x2 factorial design: EE: lambs and ewes treated with vitamin E; EC: Lambs that received oily vehicle (control) born from ewe treated with vitamin E; CC: Lambs and ewe that received oily vehicle; EC: Lambs that received vitamin E born from ewe treated with the oily vehicle. At 28 days old, all lambs were submitted to the glucose tolerance test (GTT). At 28 days old, all lambs were submitted to the glucose tolerance test (GTT) to detect insulin sensitivity. The activities of CK, AST, GGT, SOD, GSH-Px; total antioxidant status (TAS); the ability to reduce plasma iron (HRFP), thiobarbituric acid reactive substances (TBARs); the concentrations of uric acid, glucose, non-esterified fatty acids (NEFA), betahydroxybutyrate (BHB), triglycerides, cholesterol, total calcium, ionizable calcium, total protein, albumin, urea, creatinine and plasma concentration of vitamin E (alpha-tocopherol) were determined at 2 (T0) and at 28 (T1) days of life. The RQUICKI and RQUICKI BHB values were calculated in T0 and T1. The body condition score (BCS) and the live weight were measured every week. The data were analyzed using the statistical package STATISTICAL ANALYSIS SYSTEM (SAS) and for all the tests was adopted the level of significance of 5%. Parenteral administration of 60 IU / kg vitamin E in sheep on the 108th day of gestation and / or during the first 24 hours of lamb life did not influence the concentrations of total calcium, total protein, urea, albumin, TAS, cortisol, insulin; plasma concentrations of glucose, cholesterol, triglycerides, NEFA, FRAP; the activities of AST, GGT, GSH-Px and SOD; and the RQUICKI, weight and BSC values. There was only effect related to the age of the lambs for these variables. Decreased insulin sensitivity and increased alpha tocopherol concentration was observed in T0 for lambs born from ewe supplemented with vitamin E. The supplementation of the lambs improved the antioxidant status in T0 and the BHB production in T1. Alfa Tocopherol supplementation did not influence the live weight and BSC until the fourth week of life of the lambs.

In den vorliegenden Studien wurde der Fragestellung nachgegangen, wie sich unterschiedliche Fütterungsprotokolle während der Aufzuchtperiode auf den peripartalen Energie- und Fettstoffwechsel und die Insulinsensitivität von Färsen auswirken. Besonderes Augenmerk lag dabei auf der Frage, ob der „Revised Quantitative Insulin Sensitivity Check Index“ (RQUICKI) bei Färsen sinnvoll angewendet werden kann, um eine Aussage hinsichtlich der Insulinsensitivität zu treffen. Auch mögliche Auswirkungen auf das Konzeptionsalter, den Kalbeverlauf, die Milchleistung und die postpartale Morbidität wurden untersucht. Aus 46 Kälbern der Rasse Deutsche Holstein wurden drei Fütterungsgruppen gebildet. Gruppe 1 (n = 18) wurde gemäß den Richtlinien der GfE energetisch optimal gefüttert (Kontrollgruppe), Gruppe 2 (n = 14) wurde intensiv und Gruppe 3 (n = 14) restriktiv gefüttert. Im Abstand von zwei Wochen wurden die Tiere jeweils gewogen. Aus den vorliegenden Daten wurde die durchschnittliche tägliche Körpermassezunahme berechnet. Außerdem wurde zehn, sechs, drei und eine Woche vor der Kalbung sowie zwei Wochen nach der Kalbung die Rückenfettdicke (RFD) sonografisch bestimmt. Weiterhin wurden das Alter bei erfolgreicher Konzeption, Kalbeverlauf sowie Daten der Kälber, Milchleistungsprüfungsdaten und Rastzeit erfasst. Vor und nach der Kalbung wurde aus der Vena caudalis mediana Blut entnommen. Aus dem Serum wurden die Konzentrationen der folgenden Parameter bestimmt: Insulin, Insulin-like growth factor 1 (IGF-1), Glukose, freie Fettsäuren (FFS), Bilirubin, Cholesterol, Harnstoff, Betahydroxybutyrat (BHB) sowie Gesamteiweiß. Erkrankungen im postpartalen Zeitraum, wie Endometritis, Mastitis, Stoffwechselstörungen, Erkrankungen des Bewegungsapparates sowie Zyklusstörungen wurden ebenfalls in die Studien miteinbezogen. Zur Bestimmung der Insulinsensitivität wurde das Rechenmodell „Revised Quantitative Insulin Sensitivity Check Index“ (RQUICKI) verwendet. Unter Einbeziehung der Serumkonzentrationen von Glukose, Insulin und FFS lautete die Formel RQUICKI = 1/[log (Glukose) + log (Insulin) + log (FFS)]. Ein niedriger Index-Wert bedeutet eine verminderte Insulinsensitivität. Die intensiv aufgezogenen Tiere der Gruppe 2 zeigten mit 13,3 ± 1,0 Monaten ein signifikant (p = 0,003) früheres Konzeptionsalter im Gegensatz zu den Tieren der beiden anderen Gruppen (Gruppe 1: 16,0 ± 1,5 Monate; Gruppe 3: 17,7 ± 1,4 Monate). Eine Woche ante partum wiesen die Tiere der Gruppe 2 eine signifikant (p = 0,022) höhere RFD auf als die Tiere der beiden anderen Gruppen. Der RQUICKI korrelierte eine Woche ante partum signifikant negativ mit der RFD (r = -0,573; p = 0,003). RQUICKI war bei den Tieren der Gruppe 2 eine Woche ante partum signifikant (p < 0,05) niedriger als bei den Tieren der anderen Gruppen. In allen drei Gruppen konnten am dritten Tag post partum die niedrigsten Index-Werte nachgewiesen werden. Aus den errechneten Index-Werten lässt sich für Färsen für die Zeitpunkte eine Woche ante partum sowie vier Wochen post partum ein Referenzbereich von RQUICKI = 0,40 ± 0,04 ableiten. Um den dritten Laktationstag liegt bei Färsen der Referenzbereich von RQUICKI = 0,34 ± 0,02. Die intensiv aufgezogenen Färsen zeigten insgesamt mit 85,7 % die höchste Anzahl an Komplikationen bei der Kalbung, der Unterschied war statistisch allerdings nicht zu sichern. Die unterschiedliche Fütterung wirkte sich weder auf das Geschlecht der Kälber noch auf deren Geburtsgewicht aus. Signifikante Unterschiede (p < 0,05) ergaben sich bei den Serumkonzentrationen von Insulin, IGF-1, FFS und Cholesterol ante partum sowie den Bilirubin- und FFS-Konzentrationen 28 Tage post partum. Es konnten keine statistisch signifikanten Unterschiede bei den Konzentrationen von Glukose, Harnstoff, BHB und Totalprotein ermittelt werden (p > 0,05). Beim Vergleich der 305-Tage-Milchleistung wiesen die Tiere der Gruppe 2 die niedrigste Milchleistung auf. Eine signifikant (p = 0,039) höhere Inzidenz von postpartalen Zyklusstörungen war bei den Tieren der Gruppe 2 erkennbar. Eine Woche ante partum korrelierte RQUICKI signifikant negativ (r = -0,509, p = 0,008) mit dem Auftreten von Zyklusstörungen post partum. Die Untersuchungen haben gezeigt, dass durch die Fütterungsintensität während der Aufzuchtperiode die Zuchtreife, der peripartale Energie- und Fettstoffwechsel einschließlich der Insulinsensitivität, die Milchleistung sowie die postpartale Fertilität beeinflusst werden. Aus der intensiven Aufzucht resultieren eine frühere Zuchtreife, höhere Rückenfettdicken, eine gesteigerte peripartale Lipolyse einschließlich reduzierter Insulinsensitivität, eine verminderte Milchleistung und eine schlechtere Fertilität. / The aim of these studies was to investigate how different diets during the rearing period influence peripartal energy and fat metabolism as well as insulin sensitivity of heifers. Special attention was paid to the question if the „Revised Quantitative Insulin Sensitivity Check Index“ (RQUICKI) could be used to estimate insulin sensitivity in heifers. Possible influences on age at first breeding, calving, milk yield and postpartal morbidity were analysed as well. Furthermore, the aim of this investigation was to prove, if different diets at rearing influence the peripartal insulin sensitivity of heifers. 46 German Holstein calves were randomly divided in three groups. Group 1 (n = 18) was fed with an optimal diet (control group) based on recommendations of the German Society of Nutrition Physiology, group 2 (n = 14) was fed with a highly-concentrated diet and group 3 (n = 14) got a low-concentrated diet. In intervals of two weeks the heifers were weighed. With the obtained data the averaged daily weight gain was computed. In addition, ten, six, three and one week ante partum as well as two weeks post partum the backfat thickness (BFT) was measured ultrasonographically. Age at first breeding, calving, data of the calves, milk yield and interval to first service post partum were recorded, too. Before and after calving blood samples were taken from the Vena caudalis mediana. The concentrations of the following parameters were measured in blood serum: Insulin, insulin-like growth factor 1 (IGF-1), glucose, free fatty acids (FFA), bilirubin, cholesterol, urea, betahydroxybutyrat (BHB) as well as total protein. Furthermore, postpartal diseases like endometritis, mastitis, metabolic disorders, limb diseases and fertility disorders were included. To determine insulin sensitivity a mathematic model called “Revised Quantitative Insulin Sensitivity Check Index” (RQUICKI) was used. Serum concentrations of glucose, insulin and FFA were included in the formula RQUICKI = 1/[log (glucose) + log (insulin) + log (FFA)]. A low index value represents a decreased insulin sensitivity. Intensive reared heifers of group 2 reached age at first breeding (13.3 ± 1.0 months) significant (p = 0.003) earlier than heifers of the other both groups (group 1: 16.6 ± 1.5 months; group 3: 17.7 ± 1.4 months). One week ante partum heifers of group 2 showed significant (p = 0.022) higher BFT than heifers of the other groups. At the same timepoint, RQUICKI correlated significant negative with the BFT (r = -0.573; p = 0.003). In heifers of group 2, RQUICKI was significant lower (p < 0.05) one week ante partum than in heifers of the other groups. In all groups, the index values were lowest three days post partum. Based on the received index values reference ranges for RQUICKI in heifers can be proposed. One week ante partum as well as four weeks post partum the reference range for RQUICKI can be defined as RQUICKI = 0.40 ± 0.04. Three days after calving the reference range can be defined as RQUICKI = 0.34 ± 0.02. The intensive reared heifers show with an overall of 85.7 % the most difficulties at calving, but this was statistically not different. The different diets didn’t influence neither the sex of the calves nor their birth weight. Ante partum, serum concentrations of Insulin, IGF-1, FFA and cholesterol differed significantly (p < 0.05) as well as serum concentrations of bilirubin and FFA differed on day 28 post partum. No significant differences could be determined in serum concentrations of glucose, urea, BHB and total protein (p > 0.05). Heifers of group 2 showed the lowest 305-day milk yield. The incidence of postpartal ovarian diseases was significantly (p = 0.039) higher in heifers of group 2. A significant negative correlation (r = -0.509, p = 0.008) existed between RQUICKI ante partum and the incidence of postpartal ovarian diseases. In conclusion, different diets during the rearing period influence age at first breeding, peripartal energy and fat metabolism including insulin sensitivity, milk yield as well as postpartal fertility. An intensive rearing results in an earlier age at first breeding, increased BFT, enhanced peripartal lipolysis as well as reduced insulin sensitivity, decreased milk yield and poorer fertility.

O objetivo deste trabalho foi estudar os efeitos da administração parenteral de vitamina E no desempenho produtivo e na sensibilidade à insulina de cordeiros nascidos de ovelhas suplementadas ou não com vitamina E no 108º dia de gestação. Foram utilizados 28 cordeiros em delineamento de blocos casualizados, considerando o sexo dos cordeiros e tipo de gestação, se única ou gemelar; com planejamento fatorial 2X2, em que foram considerados cordeiros de ovelhas que receberam ou não vitamina E e cordeiros que receberam ou não vitamina E na dosagem de 60 UI/kg PV até 24 horas após o nascimento, distribuindo em quatro grupos: EE: Cordeiros e ovelhas que receberam vitamina E; EC: Cordeiros que receberam veículo oleoso (controle) nascidos de ovelhas que receberam vitamina E; CC: Cordeiros e ovelhas que receberam veículo oleoso; CE: Cordeiros que receberam vitamina E nascidos de ovelhas que receberam veículo oleoso. Para detecção da sensibilidade à insulina, aos 28 dias de vida (T1) os cordeiros foram submetidos ao teste de tolerância à glicose (TTG). Foram determinados aos dois (T0) e aos 28 (T1) dias de vida as atividades de CK, AST, GGT, SOD, GSH-Px; o status antioxidante total (TAS); a habilidade de redução do ferro plasmático (HRFP), as substâncias reativas ao ácido tiobarbitúrico (TBARs); as concentrações de ácido úrico, glicose, ácidos graxos não esterificados (AGNE), betahidroxibutirato (BHB), triglicerídeos, colesterol, cálcio total, cálcio ionizável, proteína total, albumina, ureia, creatinina e a concentração plasmática de vitamina E (alfa-tocoferol). Foram calculados os valores de RQUICKI e de RQUICKI BHB em T0 e em T1. Semanalmente foram acompanhados o peso e o escore de condição corporal dos cordeiros (ECC). Os dados foram analisados utilizando-se o pacote estatístico STATISTICAL ANALYSIS SYSTEM (SAS) e para todos os testes foi adotado o nível de significância de 5%. A administração parenteral de 60 UI/kg de vitamina E em ovelhas no 108o dia de gestação e/ou nas primeiras 24 horas de vida de cordeiros não influenciou as concentrações de cálcio total, proteína total, ureia, albumina, TAS, cortisol, insulina; as concentrações plasmáticas de glicose, colesterol, triglicérides, AGNE, HRFP; as atividades de AST, GGT, GSH-Px e SOD; e os valores de RQUICKI, peso e ECC. Foi observada diminuição da sensibilidade à insulina e concentração de alfa tocoferol no T0 para cordeiros nascidos de ovelhas suplementadas com vitamina E. A suplementação dos cordeiros melhorou o status antioxidante no T0 e a produção de BHB no T1. A suplementação com alfa tocoferol não influenciou no peso vivo e no ECC até a quarta semana de vida do cordeiro. / The objective of this work was to study the effects of parenteral administration of vitamin E on the productive performance and insulin sensitivity of lambs born from ewes supplemented or not with vitamin E on the 108th day of gestation. Twenty-eight lambs received intramuscularly 60 UI/kg BW of vitamin E or oily vehicle until 24 hours after birth and were distributed according to their sex and type of pregnancy (single or twin) into four groups using a 2x2 factorial design: EE: lambs and ewes treated with vitamin E; EC: Lambs that received oily vehicle (control) born from ewe treated with vitamin E; CC: Lambs and ewe that received oily vehicle; EC: Lambs that received vitamin E born from ewe treated with the oily vehicle. At 28 days old, all lambs were submitted to the glucose tolerance test (GTT). At 28 days old, all lambs were submitted to the glucose tolerance test (GTT) to detect insulin sensitivity. The activities of CK, AST, GGT, SOD, GSH-Px; total antioxidant status (TAS); the ability to reduce plasma iron (HRFP), thiobarbituric acid reactive substances (TBARs); the concentrations of uric acid, glucose, non-esterified fatty acids (NEFA), betahydroxybutyrate (BHB), triglycerides, cholesterol, total calcium, ionizable calcium, total protein, albumin, urea, creatinine and plasma concentration of vitamin E (alpha-tocopherol) were determined at 2 (T0) and at 28 (T1) days of life. The RQUICKI and RQUICKI BHB values were calculated in T0 and T1. The body condition score (BCS) and the live weight were measured every week. The data were analyzed using the statistical package STATISTICAL ANALYSIS SYSTEM (SAS) and for all the tests was adopted the level of significance of 5%. Parenteral administration of 60 IU / kg vitamin E in sheep on the 108th day of gestation and / or during the first 24 hours of lamb life did not influence the concentrations of total calcium, total protein, urea, albumin, TAS, cortisol, insulin; plasma concentrations of glucose, cholesterol, triglycerides, NEFA, FRAP; the activities of AST, GGT, GSH-Px and SOD; and the RQUICKI, weight and BSC values. There was only effect related to the age of the lambs for these variables. Decreased insulin sensitivity and increased alpha tocopherol concentration was observed in T0 for lambs born from ewe supplemented with vitamin E. The supplementation of the lambs improved the antioxidant status in T0 and the BHB production in T1. Alfa Tocopherol supplementation did not influence the live weight and BSC until the fourth week of life of the lambs.

In den vorliegenden Studien wurde der Fragestellung nachgegangen, wie sich unterschiedliche Fütterungsprotokolle während der Aufzuchtperiode auf den peripartalen Energie- und Fettstoffwechsel und die Insulinsensitivität von Färsen auswirken. Besonderes Augenmerk lag dabei auf der Frage, ob der „Revised Quantitative Insulin Sensitivity Check Index“ (RQUICKI) bei Färsen sinnvoll angewendet werden kann, um eine Aussage hinsichtlich der Insulinsensitivität zu treffen. Auch mögliche Auswirkungen auf das Konzeptionsalter, den Kalbeverlauf, die Milchleistung und die postpartale Morbidität wurden untersucht. Aus 46 Kälbern der Rasse Deutsche Holstein wurden drei Fütterungsgruppen gebildet. Gruppe 1 (n = 18) wurde gemäß den Richtlinien der GfE energetisch optimal gefüttert (Kontrollgruppe), Gruppe 2 (n = 14) wurde intensiv und Gruppe 3 (n = 14) restriktiv gefüttert. Im Abstand von zwei Wochen wurden die Tiere jeweils gewogen. Aus den vorliegenden Daten wurde die durchschnittliche tägliche Körpermassezunahme berechnet. Außerdem wurde zehn, sechs, drei und eine Woche vor der Kalbung sowie zwei Wochen nach der Kalbung die Rückenfettdicke (RFD) sonografisch bestimmt. Weiterhin wurden das Alter bei erfolgreicher Konzeption, Kalbeverlauf sowie Daten der Kälber, Milchleistungsprüfungsdaten und Rastzeit erfasst. Vor und nach der Kalbung wurde aus der Vena caudalis mediana Blut entnommen. Aus dem Serum wurden die Konzentrationen der folgenden Parameter bestimmt: Insulin, Insulin-like growth factor 1 (IGF-1), Glukose, freie Fettsäuren (FFS), Bilirubin, Cholesterol, Harnstoff, Betahydroxybutyrat (BHB) sowie Gesamteiweiß. Erkrankungen im postpartalen Zeitraum, wie Endometritis, Mastitis, Stoffwechselstörungen, Erkrankungen des Bewegungsapparates sowie Zyklusstörungen wurden ebenfalls in die Studien miteinbezogen. Zur Bestimmung der Insulinsensitivität wurde das Rechenmodell „Revised Quantitative Insulin Sensitivity Check Index“ (RQUICKI) verwendet. Unter Einbeziehung der Serumkonzentrationen von Glukose, Insulin und FFS lautete die Formel RQUICKI = 1/[log (Glukose) + log (Insulin) + log (FFS)]. Ein niedriger Index-Wert bedeutet eine verminderte Insulinsensitivität. Die intensiv aufgezogenen Tiere der Gruppe 2 zeigten mit 13,3 ± 1,0 Monaten ein signifikant (p = 0,003) früheres Konzeptionsalter im Gegensatz zu den Tieren der beiden anderen Gruppen (Gruppe 1: 16,0 ± 1,5 Monate; Gruppe 3: 17,7 ± 1,4 Monate). Eine Woche ante partum wiesen die Tiere der Gruppe 2 eine signifikant (p = 0,022) höhere RFD auf als die Tiere der beiden anderen Gruppen. Der RQUICKI korrelierte eine Woche ante partum signifikant negativ mit der RFD (r = -0,573; p = 0,003). RQUICKI war bei den Tieren der Gruppe 2 eine Woche ante partum signifikant (p < 0,05) niedriger als bei den Tieren der anderen Gruppen. In allen drei Gruppen konnten am dritten Tag post partum die niedrigsten Index-Werte nachgewiesen werden. Aus den errechneten Index-Werten lässt sich für Färsen für die Zeitpunkte eine Woche ante partum sowie vier Wochen post partum ein Referenzbereich von RQUICKI = 0,40 ± 0,04 ableiten. Um den dritten Laktationstag liegt bei Färsen der Referenzbereich von RQUICKI = 0,34 ± 0,02. Die intensiv aufgezogenen Färsen zeigten insgesamt mit 85,7 % die höchste Anzahl an Komplikationen bei der Kalbung, der Unterschied war statistisch allerdings nicht zu sichern. Die unterschiedliche Fütterung wirkte sich weder auf das Geschlecht der Kälber noch auf deren Geburtsgewicht aus. Signifikante Unterschiede (p < 0,05) ergaben sich bei den Serumkonzentrationen von Insulin, IGF-1, FFS und Cholesterol ante partum sowie den Bilirubin- und FFS-Konzentrationen 28 Tage post partum. Es konnten keine statistisch signifikanten Unterschiede bei den Konzentrationen von Glukose, Harnstoff, BHB und Totalprotein ermittelt werden (p > 0,05). Beim Vergleich der 305-Tage-Milchleistung wiesen die Tiere der Gruppe 2 die niedrigste Milchleistung auf. Eine signifikant (p = 0,039) höhere Inzidenz von postpartalen Zyklusstörungen war bei den Tieren der Gruppe 2 erkennbar. Eine Woche ante partum korrelierte RQUICKI signifikant negativ (r = -0,509, p = 0,008) mit dem Auftreten von Zyklusstörungen post partum. Die Untersuchungen haben gezeigt, dass durch die Fütterungsintensität während der Aufzuchtperiode die Zuchtreife, der peripartale Energie- und Fettstoffwechsel einschließlich der Insulinsensitivität, die Milchleistung sowie die postpartale Fertilität beeinflusst werden. Aus der intensiven Aufzucht resultieren eine frühere Zuchtreife, höhere Rückenfettdicken, eine gesteigerte peripartale Lipolyse einschließlich reduzierter Insulinsensitivität, eine verminderte Milchleistung und eine schlechtere Fertilität. / The aim of these studies was to investigate how different diets during the rearing period influence peripartal energy and fat metabolism as well as insulin sensitivity of heifers. Special attention was paid to the question if the „Revised Quantitative Insulin Sensitivity Check Index“ (RQUICKI) could be used to estimate insulin sensitivity in heifers. Possible influences on age at first breeding, calving, milk yield and postpartal morbidity were analysed as well. Furthermore, the aim of this investigation was to prove, if different diets at rearing influence the peripartal insulin sensitivity of heifers. 46 German Holstein calves were randomly divided in three groups. Group 1 (n = 18) was fed with an optimal diet (control group) based on recommendations of the German Society of Nutrition Physiology, group 2 (n = 14) was fed with a highly-concentrated diet and group 3 (n = 14) got a low-concentrated diet. In intervals of two weeks the heifers were weighed. With the obtained data the averaged daily weight gain was computed. In addition, ten, six, three and one week ante partum as well as two weeks post partum the backfat thickness (BFT) was measured ultrasonographically. Age at first breeding, calving, data of the calves, milk yield and interval to first service post partum were recorded, too. Before and after calving blood samples were taken from the Vena caudalis mediana. The concentrations of the following parameters were measured in blood serum: Insulin, insulin-like growth factor 1 (IGF-1), glucose, free fatty acids (FFA), bilirubin, cholesterol, urea, betahydroxybutyrat (BHB) as well as total protein. Furthermore, postpartal diseases like endometritis, mastitis, metabolic disorders, limb diseases and fertility disorders were included. To determine insulin sensitivity a mathematic model called “Revised Quantitative Insulin Sensitivity Check Index” (RQUICKI) was used. Serum concentrations of glucose, insulin and FFA were included in the formula RQUICKI = 1/[log (glucose) + log (insulin) + log (FFA)]. A low index value represents a decreased insulin sensitivity. Intensive reared heifers of group 2 reached age at first breeding (13.3 ± 1.0 months) significant (p = 0.003) earlier than heifers of the other both groups (group 1: 16.6 ± 1.5 months; group 3: 17.7 ± 1.4 months). One week ante partum heifers of group 2 showed significant (p = 0.022) higher BFT than heifers of the other groups. At the same timepoint, RQUICKI correlated significant negative with the BFT (r = -0.573; p = 0.003). In heifers of group 2, RQUICKI was significant lower (p < 0.05) one week ante partum than in heifers of the other groups. In all groups, the index values were lowest three days post partum. Based on the received index values reference ranges for RQUICKI in heifers can be proposed. One week ante partum as well as four weeks post partum the reference range for RQUICKI can be defined as RQUICKI = 0.40 ± 0.04. Three days after calving the reference range can be defined as RQUICKI = 0.34 ± 0.02. The intensive reared heifers show with an overall of 85.7 % the most difficulties at calving, but this was statistically not different. The different diets didn’t influence neither the sex of the calves nor their birth weight. Ante partum, serum concentrations of Insulin, IGF-1, FFA and cholesterol differed significantly (p < 0.05) as well as serum concentrations of bilirubin and FFA differed on day 28 post partum. No significant differences could be determined in serum concentrations of glucose, urea, BHB and total protein (p > 0.05). Heifers of group 2 showed the lowest 305-day milk yield. The incidence of postpartal ovarian diseases was significantly (p = 0.039) higher in heifers of group 2. A significant negative correlation (r = -0.509, p = 0.008) existed between RQUICKI ante partum and the incidence of postpartal ovarian diseases. In conclusion, different diets during the rearing period influence age at first breeding, peripartal energy and fat metabolism including insulin sensitivity, milk yield as well as postpartal fertility. An intensive rearing results in an earlier age at first breeding, increased BFT, enhanced peripartal lipolysis as well as reduced insulin sensitivity, decreased milk yield and poorer fertility.