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Master's Dissertation
DOI
Document
Author
Full name
José Paulo Roman Barroso
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Pirassununga, 2019
Supervisor
Committee
Pires, Alexandre Vaz (President)
Ferraz Junior, Marcos Vinicius de Castro
Ferreira, Evandro Maia
Title in Portuguese
Efeito do ritmo de ganho de peso e da DEP do touro na puberdade de novilhas cruzadas (Angus x Nelore) desmamadas precocemente
Keywords in Portuguese
Alto concentrado
Cruzamento
Ganho compensatório
IGF-1
Metabolic Imprinting
Abstract in Portuguese
A puberdade de novilhas de corte é um fator limitante para o aumento da produtividade, sendo influenciada por diversos fatores. O objetivo desse estudo foi avaliar o ritmo de ganho de peso dos três aos sete meses de idade e a DEP do touro na puberdade de novilhas de corte. Foram utilizadas 60 novilhas F1 (Angus x Nelore) desmamadas precocemente (102 ± 4,3 dias; 103 ± 4,7 kg) em um experimento arranjado em esquema fatorial 2x2. O fator 1 foi o Ritmo de Ganho no período 1 (3 a 7 meses de idade) no qual as novilhas foram submetidas a Alto GMD, com CMS ad libitum (GA; GMD estimado em 1000 g/animal/dia, n = 30 novilhas) ou submetidas a Médio GMD, com CMS de 1,5% do peso corporal (GM; GMD estimado em 700 g/animal/dia, n = 30 novilhas). No período 2 (do 7o mês de idade até a puberdade), todas as novilhas receberam a dieta ad libitum. O fator 2 foi a DEP para circunferência escrotal (CE) do touro progenitor da novilha, sendo considerados sexualmente precoces os touros com DEP Positiva (DP) e tardios os touros com DEP Negativa (DN). Foram mensurados os GMD, CMS, EA ao final de cada período; peso aos sete meses; idade, peso e ECC na puberdade; taxa de puberdade e concentrações séricas de IGF-1 e insulina nos meses 3, 5, 7, 10 e 12. A análise estatística foi realizada pelo SAS 9.3. Houve interação entre os fatores apenas para CMS no período 1 (P = 0,02). Considerando o Ritmo de Ganho, novilhas do GA apresentaram maiores CMS (P < 0,0001) e GMD (P < 0,0001) no período 1 em relação a novilhas do GM. Em consequência, o peso aos sete meses também foi maior (P = 0,002). No período 2, as novilhas GM apresentaram GMD superior (P = 0,05) as novilhas GA. Considerando a DEP, novilhas de DP apresentaram maiores CMS (P = 0,03) e GMD (P = 0,07) no período 2, em relação a novilhas de DN. As novilhas DP foram mais pesadas aos sete meses (P = 0,02) e na puberdade (P = 0,0005). A taxa de puberdade aos 15 meses foi maior para as novilhas DP (P = 0,03). Não houve redução da idade à puberdade de novilhas Angus x Nelore pela diferença no Ritmo de Ganho dos 3 aos 7 meses. A DEP para CE de touros precoces aumentou a taxa de puberdade de novilhas Angus x Nelore aos 15 meses de idade.
Title in English
Effect of rate of weight gain and EPD of the sire on puberty of crossbreed heifers (Angus x Nellore) weaned early
Keywords in English
Compensatory gain
IGF-1
Metabolic imprinting
Precocity
Puberty rate
Abstract in English
The puberty in beef heifers is a limiting factor for the increase of productivity, being influenced by several factors. The aim of this study was to evaluate the rate of weight gain from three to seven months of age and the EPD of the bull on puberty of beef heifers. Sixty F1 heifers (Angus x Nellore) weaned early (102 ± 4.3 days; 103 ± 4.7 kg) were used in an experiment arranged in a 2x2 factorial scheme. Factor 1 was the Rate of Gain in period 1 (3 to 7 months of age) in which heifers were submitted to High ADG, with DMI ad libitum (HG; ADG estimated at 1000 g / animal / day, n = 30 heifers ) or submitted to Medium ADG, with DMI of 1.5% of body weight (MG; GMD estimated at 700 g / animal / day, n = 30 heifers). In period 2 (from the 7th month of age until puberty), all heifers received the ad libitum diet. Factor 2 was the EPD for scrotal circumference (SC) of the sire: Positive EPD (PE) of the precocious sires and Negative EPD (NE) of the non-precocious sires. ADG, DMI and FE were measured at the end of each period; weight at seven months; age, weight and BCS at puberty; rate of puberty and serum concentrations of IGF-1 and insulin at months 3, 5, 7, 10 and 12. Statistical analysis were performed by SAS 9.3. There was interaction between factors only for CMS in period 1 (P = 0.02). Considering the Rate of Gain, HG heifers showed higher DMI (P <0.0001) and ADG (P <0.0001) in period 1 in relation to MG heifers. Consequently, the weight at seven months was also higher (P = 0.002). In period 2, MG heifers presented higher ADG (P = 0.05) than HG heifers. Considering the EPD, heifers of PE presented higher DMI (P = 0.03) and ADG (P = 0.07) in period 2, in relation to NE heifers. The PE heifers were heavier at seven months (P = 0.02) and at puberty (P = 0.0005). The puberty rate at 15 months was higher for PE heifers (P = 0.03). There was no reduction in the age at puberty of Angus x Nellore heifers by the difference in the Rate of Gain from 3 to 7 months. The EPD for SC of precocious bulls increased the puberty rate of Angus x Nellore heifers at 15 months of age.
 
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Publishing Date
2019-10-18
 
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