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Doctoral Thesis
DOI
https://doi.org/10.11606/T.10.2007.tde-28092007-144519
Document
Author
Full name
Fernanda Altieri Ferreira
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Binelli, Mario (President)
Paula, Luiz Augusto de Castro e
Rennó, Francisco Palma
Rodrigues, Paulo Henrique Mazza
Sartori Filho, Roberto
Title in Portuguese
Alimentação de novilhas com uréia por curto prazo afeta a qualidade de complexos cumulus oócito e o desenvolvimento de embriões In vitro
Keywords in Portuguese
Bovinos (fêmeas)
Embrião
Oócito
Uréia
Abstract in Portuguese
A utilização de uréia na alimentação de fêmeas bovinas pode prejudicar o desempenho reprodutivo destes animais, provavelmente decorrente do aumento do teor de nitrogênio uréico plasmático (NUP). O objetivo deste estudo foi avaliar se alimentação com uréia por curto prazo oferecida a novilhas, e conseqüente aumento de NUP, exerce influência sobre a quantidade, qualidade e competência dos complexos cumulus-oócito (CCO). O experimento teve duração de 62 dias, dividido em oito semanas e dois períodos. Foram utilizadas 40 novilhas mestiças mantidas a pasto, alocadas a dois tratamentos, utilizando-se delineamento "cross-over": dieta sem uréia (SU): 5 kg (matéria original) de silagem de milho e 1 kg de concentrado/animal/dia ou dieta com uréia (U): 5 kg de silagem de milho e 1 kg de concentrado contendo 75 g de uréia/animal/dia. Os animais selecionados a cada semana receberam as dietas por seis dias, uma única vez ao dia. No sexto dia de oferecimento das dietas, foram realizadas aspiração folicular (OPU) e colheita de sangue, em jejum e 3 horas após a alimentação. Imediatamente após a OPU, foi realizada contagem total de CCO recuperados e classificação dos mesmos em viáveis e inviáveis. Apenas os viáveis foram destinados à produção In vitro de embriões. Em relação ao teor de NUP, houve efeito de interação entre tratamento e tempo de colheita (P=0,04) e dentro de cada tempo foi observado aumento significativo (P<0,01) para os animais do tratamento U. Não foi observado efeito de tratamento em relação ao número total de CCO recuperados por animal (média ± EPM: SU=9,15 ± 0,82 vs. U=8,82 ± 0,95), nem sobre a porcentagem de CCO viáveis sobre total de CCO recuperados por animal (SU=73,61% ± 2,47 vs. U=70,26% ± 2,31). A taxa de clivagem obtida no dia 3 após a inseminação In vitro (IIV) e as taxas de blastocisto nos dias 6, 7 e 9 após a IIV, não foram influenciadas pelo tratamento. Porém, no 11º pós IIV, houve diminuição (P=0,04) da taxa de blastocistos eclodidos para o tratamento U (SU=82,50% ± 0,05 vs. U=64,33% ± 0,07). Apesar do aumento do teor de NUP observado nas novilhas do tratamento U, a quantidade, qualidade e competência dos CCO durante as primeiras clivagens até atingirem o estádio de blastocisto In vitro não foram influenciadas pelo oferecimento de 75 g de uréia na dieta, durante seis dias. Porém, foi observada redução da taxa de eclosão dos blastocistos das novilhas do tratamento U.
Title in English
Short-term urea feeding affect quality of cumulus oocyte complexes and In vitro embryo development
Keywords in English
Bovine (female)
Embryo
Oocyte
Urea
Abstract in English
Urea feeding offered to bovine dams may damage their reproductive performance, probably due to an increase in levels of plasmatic urea nitrogen (PUN). The aim of this study was evaluate if short-term urea feeding of heifers, following high PUN levels, would have an influence on the quantity, quality and competence of cumulus-oocyte complexes (COC). Trial lasted 62 days, divided into eight weeks and two periods. Forty crossbred grazing heifers were allocated to one of two treatments, using a cross-over design: diet without urea (WU): 5 kg (as fed) of corn silage and 1 kg of concentrated/animal/day, or diet with urea (U): 5 kg of corn silage and 1 kg of concentrated with 75 g of urea/animal/day. Heifers selected in each week received these diets once a day, for six days. On the sixth day of diets? offer, ovum pick-up (OPU) and blood sampling at fasting and 3 hours after feeding were carried out. Immediately after OPU, total COC recovered was counted and classified as either viable or unviable. Only viable were destined to In vitro embryo production. In relation to PUN level, there was a significant interaction between treatment and sampling time (P=0.04) and a significant (P<0.01) increase in animals undergoing U treatment for each of the test times. No significant effect was observed relative to either the total number of recovered COC per animal (mean ± SEM: WU=9.15 ± 0.82 vs. U=8.82 ± 0.95), or the viable COC as a percentage of total recovered COC per animal (WU=73.61% ± 2.47 vs. U=70.26% ± 2.31). Cleavage ratio assessed on day 3 post In vitro insemination (IVI) and blastocyst ratio on days 6, 7 and 9 post IVI were not influenced by treatments. However, there was a significant treatment effect (P=0.04) in relation to hatched blastocysts on day 11 after IVI (WU=83% ± 0.05 vs. U=64% ± 0.07). Even though higher PUN levels were observed in animals from treatment U, quantity, quality and competence of the COC during first cleavages until reaching the blastocyst stage In vitro were not influenced by adding 75 g of urea on the diet offered to heifers, during six days. Neverthless, a decline in hatched blastocysts rate was observed in heifers of treatment U.
 
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Publishing Date
2007-10-02
 
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