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Doctoral Thesis
DOI
https://doi.org/10.11606/T.10.2016.tde-06102016-163624
Document
Author
Full name
Marcos Vinicius de Castro Ferraz Junior
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Pirassununga, 2016
Supervisor
Committee
Pires, Alexandre Vaz (President)
Barreto Filho, João Bosco
Binelli, Mario
Cappellozza, Bruno Ieda
Santos, Flavio Augusto Portela
Title in Portuguese
Puberdade de novilhas: 1 - Efeito da nutrição e da DEP do touro para precocidade sexual na puberdade de novilhas Nelore; 2 - Efeito da desmama precoce e da nutrição no imprinting metabólico sobre a puberdade de novilhas Nelore e cruzadas (Angus x Nelore)
Keywords in Portuguese
Imprinting metabólico
Desmama precoce
Genética
Nelore
Nutrição
Puberdade
Abstract in Portuguese
O objetivo do experimento I foi avaliar a interação entre dois ganhos médios diários [GMD - fator nutricional (ganho elevado GA = 0,700 e ganho baixo GB = 0,300 Kg/dia)] e a diferença esperada da progênie (DEP para idade ao primeiro parto - fator genético) na puberdade de novilhas Nelore. Foram utilizadas 58 novilhas desmamadas com 8 meses de idade, filhas de 4 touros [2 precoces (P) e 2 tardios (T)], formando um esquema fatorial 2 x 2, no qual o fator 1 foi o GMD e o fator 2 foi a DEP do touro, constituindo assim quatro tratamentos: Touro precoce com GMD elevado (PGA), touro precoce com GMD baixo (PGB), touro tardio com GMD elevado (TGA), touro tardio com GMD baixo (TGB). Houve efeito dos tratamentos na porcentagem de novilhas púberes durante o experimento (PGA e PGB = 100%; TGA = 83% até 27 meses de idade; TGB = 38% até 3 anos de idade). As novilhas do PGA apresentaram a menor (P = 0,0001) idade na puberdade (18 ± 1 meses). Contudo, a nutrição atrasou a puberdade em cerca de 10 meses nas novilhas filhas de touros precoces e tardios (PGA = 18 ± 1 vs. PGB = 29 ± 1 meses; TGA = 24 ± 1 vs. TGB = 34 ± 1 meses). Assim podemos concluir que a DEP para IPP foi o fator necessário para o adiantamento da idade a puberdade. No entanto, o GMD foi um fator limitante para o aparecimento da puberdade. O objetivo do experimento II foi avaliar o efeito do imprinting metabólico dos 3 aos 7 meses de idade na puberdade em novilhas cruzadas (Angus x Nelore). Os tratamentos foram arranjados em esquema fatorial 2 x 2, no qual o fator 1 foi GMD elevado e médio dos 3 aos 7 meses de idade (fase 1) e o fator 2 foi GMD elevado e médio dos 7 meses de idade até a puberdade (fase 2). Formando os seguintes tratamentos: CAA Novilhas cruzadas submetidas ao GMD elevado nas fases 1 e 2; CAM - GMD elevado na fase 1 e GMD médio na fase 2; CMA- GMD médio na fase1 e GMD elevado na fase 2; CMM GMD médio nas fases 1 e 2. O GMD médio foi atingido pela restrição do consumo de matéria seca (CMS) no GMD médio. As novilhas dos tratamentos CAA, CAM e CMA apresentaram puberdade na mesma idade (cerca de 12 meses). As novilhas cruzadas submetidas ao GMD elevado na fase 2 foram mais pesadas (P = 0,0379) na puberdade do que novilhas submetidas ao baixo GMD. O GMD elevado dos 3 aos 7 meses de idade não impactou na puberdade das novilhas cruzadas. O objetivo e a metodologia do experimento III foram semelhantes ao experimento II, no entanto foram utilizadas novilhas Nelore (N) ao invés de cruzadas e o experimento terminou aos 19 meses de idade. O tratamento NAA (84%) induziu maior (P = 0,0145) proporção de novilhas púberes do que o NMM (23%), mas não houve diferença na taxa de puberdade entre os tratamentos NAM (60%) e NMA (50%). Além disso, o comportamento das curvas de puberdade dos tratamentos NAM e NMA foram semelhantes, sendo assim não houve efeito de imprinting metabólico nas novilhas Nelore. O GMD elevado dos 3 aos 19 meses idade aumentou a porcentagem de novilhas Nelore púberes aos 19 meses de idade
Title in English
Puberty of heifers: 1 - Effect of nutrition and EPD of sire for sexual precocity on puberty in Nellore heifers; 2 - Effect of early weaning and nutrition in metabolic imprinting on puberty in Nellore and crossbreed (Angus x Nellore) heifers
Keywords in English
Early weaning
Genetics
Metabolic imprinting
Nellore
Nutrition
Puberty
Abstract in English
The objective of experiment I was to evaluate the interaction between two average daily gain (ADG nutritional factor (high gain HG = 0,700 and low gain LG = 0,300 kg/day)] and expected progeny differences (EPD to age at first calving; genetic factor) on puberty attainment of Nellore heifers. Fifth eight heifers weaned at 8 months of age and daughters of 4 sires [2 precocious (P) and 2 later (L)]. A factorial design 2 x 2 was used, where the factor 1 was the ADG and the factor 2 was the EPD of sire, resulting in four treatments: Precocious sire with HG (PHG), precocious sire with LG (PLG), later sire with HG (LHG) and later sire with LG (LLG). There was effect of treatment in the percentage of pubertal heifers (PHG and PLG = 100%; LHG = 83% until 27 month of age; LLG = 38% until 3 years old). Heifers from the PHG treatment were the youngest (P = 0,0001) (18 months of age). However, the nutritional factor delayed puberty achievement by approximately 10 months the age at puberty in precocious and later heifers (PHG = 18 ± 1 vs. PLG = 29 ± 1 months; LHG = 24 ± 1 vs. LLG = 34 ± 1 months of age). The EPD to age at first calving was the main factor affecting the age at puberty. However, the ADG was limiting to puberty onset. The objective of experiment II was to evaluate the effect of metabolic imprinting from 3 to 7 months of age on puberty attainment of crossbreed heifers (Angus x Nellore). The treatments were arranged in 2 x 2 factorial design, where the factor 1 was high (H) and medium (M) ADG from 3 to 7 months of age (phase 1) and the factor 2 was high and medium ADG from 7 months of age to puberty onset (phase 2), resulting in the following treatments: CHH crossbreed heifers submitted to high ADG in both phases of experiment; CHM high ADG in phase 1 and medium ADG in phase 2; CMH medium ADG in phase 1 and high ADG in phase 2; CMM Medium ADG in both phases. The medium ADG were targeted by restricting of dry mater intake (DMI) in medium ADG. Crossbreed heifers of treatments CHH, CHM, CMH showed the same age at puberty, about 12 months. Heifers submitted to high ADG on phase 2 were heavier (P = 0,0379) at puberty than heifers submitted to low ADG. The high ADG from 3 to 7 months did not affect puberty onset in crossbreed heifers. The objective and methodology used in experiment III was the same of used in experiment II. However, Nellore heifers (N) were used instead of crossbreed heifers and the experimental period ended at 19 months of age. The NHH treatment (84%) induced higher (P = 0,0145) percentage of pubertal heifers than NMM (23%), but there was not difference in puberty rate between NHM (60%) and NMH (50%) treatments. Furthermore, the comportment of curves of puberty of treatments NHM and NMH were similar, thus there was not effect of metabolic imprinting in Nellore heifers. The high ADG from 3 to 19 months of age increased the percentage of pubertal Nellore heifers at 19 months of age
 
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Publishing Date
2016-10-14
 
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