RESUMO
The aim of this study was to investigate the expression of genes encoding enzymes and other factors involved with carbohydrate and lipid metabolism in the liver of 2 genetic groups of dairy cows during the transition period. We analyzed the expression of glucose-6-phosphatase (G6PC), cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), methylmalonyl-CoA mutase (MUT), ß-hydroxybutyrate dehydrogenase-2 (BDH2), acetyl-CoA carboxylase (ACC), carnitine palmitoyltransferase-2 (CPT2), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), glucose transporter-2 (SLC2A2), and the transcription factor peroxisome proliferator-activated receptor α (PPARA). Blood concentrations of glucose, nonesterified fatty acids, and ß-hydroxybutyrate were also determined. Liver biopsies and blood samples were taken at d 15 prepartum and at d 6, 21, 36, 51, and 66 postpartum from Holsteins (n = 6) and F1 Holstein-Gir (n = 6) cows. Cows were kept under the same prepartum and postpartum management conditions. The results showed that the expression of G6PC, PEPCK-C, BDH2, ACC, CPT2, HMGCR, SLC2A2, and PPARA genes did not differ between genetic groups. Except for PEPCK-C, no interaction between genetic groups and the experimental period was observed. Within both groups of cows, G6PC and PEPCK-C gene expression decreased when comparing prepartum gene expression with 21 and 36 DIM, and increased in d 51 postpartum. MUT mRNA levels differed between the 2 genetic groups and displayed a significant increase after d 36 postpartum, whereas mRNA levels of HMGCR tended to increase when comparing d 21 and 36 to d 51 postpartum. Glucose concentrations also differed between genetic groups, being significantly higher in the plasma of F1 Holstein-Gir cows than in Holstein cows, but no differences were found within each group during the analysis period. ß-Hydroxybutyrate and nonesterified fatty acid concentrations did not differ between genetic groups, but displayed increased levels from prepartum to d 6 and 21 postpartum. Our results indicated that expression in the liver of genes involved with glucose and fatty acid metabolism were similar in both groups of cows and significant differences were observed between the 2 groups in the expression of MUT, a gene involved in propionate metabolism.
Assuntos
Metabolismo dos Carboidratos/genética , Bovinos/genética , Metabolismo Energético/genética , Metabolismo dos Lipídeos/genética , Fígado/metabolismo , Animais , Bovinos/metabolismo , Feminino , Hibridização Genética , Período Pós-PartoRESUMO
Avaliaram-se suplementos nitrogenados contendo ou não monensina sódica, adicionados à silagem, sobre o consumo de matéria seca (CMS), a digestibilidade da MS (DMS) e a produção de vacas F1 Holandês x Zebu. Vacas (n=15) com 21 dias em lactação, produzindo 19,2kg/dia, foram distribuídas em um delineamento quadrado latino 5X5, com três vacas por tratamento (T). Os T foram: 1- concentrado durante as ordenhas e silagem de milho após as ordenhas (C.SM); 2- C.SM + nitromineral (C.SMNM); 3- C.SM + nitroproteico (C.SMNP), 4- C.SMNM + monensina (C.SMNM+MO) e 5- C.SMNP + monensina (C.SMNP+MO). Os suplementos NP e NM adicionados à SM, (C.SMNP e C.SMNM) aumentaram o CMS (P<0,05). A adição de monensina não alterou o CMS nem a DMS (P>0,05). A suplementação proteica não aumentou o acetato (P>0,05), mas aumentou o propionato e o butirato (P<0,05). A adição de MO ao T C.SMNP reduziu o propionato e o butirato (P<0,05) em relação ao T C.SMNP. A concentração de nitrogênio amoniacal aumentou (P<0,05) no T C.SMNM em relação ao T C.SM e não diferiu dos demais. As produções de leite nos T C.SMNP e C.SMNPMO foram maiores do que no T C.SM (P<0,05). Vacas do T C.SM foram mais eficientes produzindo leite do que as do T C.SMNM (P<0,05).
The objectives of this study were to evaluate consumption, ruminal parameters and milk production of F1 Holstein x Zebu milking cows fed nitrogenated supplements with or without monensin added to the silage. Cows with 21 days on milk and producing initially 19.2kg of milk/day were distributed in a 5X5 Latin square design with three replicates per treatment. The treatments (T) were: 1- concentrate fed during the milking time and corn silage fed after milking (C.SM); 2- C.SM + nitromineral(NM) (C.SMNM); 3- C.SM + nitroproteico (NP) (C.SMNP); 4- C.SMNM + monensin (C.SMNM+MO) e 5- C.SMNP + monensin (C.SMNP+MO). The addition of NP e NM to the T C.SM increased the DMI when compared to C.SM (P<0.05). The addition of monensin did not change the DMI (P>0,05). The protein supplementation did not alter acetate (P>0,05), but increased propionate and butyrate concentrations. (P<0.05) The N-NH3 concentration increased (P<0.05) only in T C.SMNM (P<0.05). The addition of monensin to T C.SMNP decreased propionate and butyrate concentrations (P<0.05) related to T C.SMNP. The milk production was greater in the C.SMNP treatments than T C.SM (P<0.05). Cows in T C.SM produced milk more efficiently than cows fed C.SMNM (P<0.05), but did not differ from the others.
Assuntos
Animais , Bovinos , Substitutos do Leite Humano , Nitrogênio/química , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição do Lactente , Bovinos/classificaçãoRESUMO
Avaliaram-se suplementos nitrogenados contendo ou não monensina sódica, adicionados à silagem, sobre o consumo de matéria seca (CMS), a digestibilidade da MS (DMS) e a produção de vacas F1 Holandês x Zebu. Vacas (n=15) com 21 dias em lactação, produzindo 19,2kg/dia, foram distribuídas em um delineamento quadrado latino 5X5, com três vacas por tratamento (T). Os T foram: 1- concentrado durante as ordenhas e silagem de milho após as ordenhas (C.SM); 2- C.SM + nitromineral (C.SMNM); 3- C.SM + nitroproteico (C.SMNP), 4- C.SMNM + monensina (C.SMNM+MO) e 5- C.SMNP + monensina (C.SMNP+MO). Os suplementos NP e NM adicionados à SM, (C.SMNP e C.SMNM) aumentaram o CMS (P<0,05). A adição de monensina não alterou o CMS nem a DMS (P>0,05). A suplementação proteica não aumentou o acetato (P>0,05), mas aumentou o propionato e o butirato (P<0,05). A adição de MO ao T C.SMNP reduziu o propionato e o butirato (P<0,05) em relação ao T C.SMNP. A concentração de nitrogênio amoniacal aumentou (P<0,05) no T C.SMNM em relação ao T C.SM e não diferiu dos demais. As produções de leite nos T C.SMNP e C.SMNPMO foram maiores do que no T C.SM (P<0,05). Vacas do T C.SM foram mais eficientes produzindo leite do que as do T C.SMNM (P<0,05).(AU)
The objectives of this study were to evaluate consumption, ruminal parameters and milk production of F1 Holstein x Zebu milking cows fed nitrogenated supplements with or without monensin added to the silage. Cows with 21 days on milk and producing initially 19.2kg of milk/day were distributed in a 5X5 Latin square design with three replicates per treatment. The treatments (T) were: 1- concentrate fed during the milking time and corn silage fed after milking (C.SM); 2- C.SM + nitromineral(NM) (C.SMNM); 3- C.SM + nitroproteico (NP) (C.SMNP); 4- C.SMNM + monensin (C.SMNM+MO) e 5- C.SMNP + monensin (C.SMNP+MO). The addition of NP e NM to the T C.SM increased the DMI when compared to C.SM (P<0.05). The addition of monensin did not change the DMI (P>0,05). The protein supplementation did not alter acetate (P>0,05), but increased propionate and butyrate concentrations. (P<0.05) The N-NH3 concentration increased (P<0.05) only in T C.SMNM (P<0.05). The addition of monensin to T C.SMNP decreased propionate and butyrate concentrations (P<0.05) related to T C.SMNP. The milk production was greater in the C.SMNP treatments than T C.SM (P<0.05). Cows in T C.SM produced milk more efficiently than cows fed C.SMNM (P<0.05), but did not differ from the others.(AU)