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| Author(s): |
Fábio Cortez Leite de Oliveira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Pirassununga. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT) |
| Defense date: | 2014-12-10 |
| Examining board members: |
Valdo Rodrigues Herling;
Ives Cláudio da Silva Bueno;
Lilian Elgalise Techio Pereira;
Ricardo Andrade Reis;
João Maurício Bueno Vendramini
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| Advisor: | Valdo Rodrigues Herling |
| Abstract | |
The circadian rhythms of plants and twilight ruminants seem to have co-evolved in the same direction: \"to harvest solar energy\" during day, to store the exceeding and to use it during night. Indeed, the hourly management of forage harvesting emerges as a possibility to increment forage based production systems efficiency at zero cost. The objective of the trial was to determine in what day time it\'s advantageous to focus the harvest of Brachiaria brizantha cv. either under clipping or grazing. During spring and summer of 2012/13, there were experiments to determine what is day time when the maximum concentration of sugars and starch (non-structural carbohydrates) occurs in leaf blades and pseudostems of Marandugrass, and to verify the variability patterns along the day and among the vertical sward strata. The non-structural carbohydrates accumulation of leaf blades and pseudostems, from sunrise to the beginning of the night, have quadratic patterns and its maximum concentration occurs after 15 h. Thus, the non-structural carbohydrates concentration were greater at the top sward stratum, at 15 h, mainly on spring. On the other hand, concentrations of N, fiber and dry matter digestibility varied lesser along the day and more due to different strata and year seasons. At the same period, a grazing experiment was carried to verify whether the time of moving to another paddock affected intake behavior and performance of beef heifers. Six groups were managed under rotational stocking, being three moved at 6 h and three moved at 15 h. Forage nutritive value was evaluated at pre and during grazing conditions, by the sunrise and the afternoon, and the intake behavior of the groups was evaluated by both time use and bite rate monitoring. Moving the herd at 15 h shifted the feeding behavior and concentrated grazing activity at afternoon, when forage nutritive value is higher, compared to the sunrise. However, moving animals at sunrise increased the total daily grazing time, evenly distributed among morning and afternoon. Concluding, this research brings new information regarding the harvest of Marandugrass, like the possibility of harvesting forages with significant increments of non-structural carbohydrates through harvesting after 15 h and above 13 cm on spring and above 20 cm on summer. Regarding animals moving time, even though moving at 15 h shifted grazing behavior, there was compensation between grazing patterns and forage nutritive value variations along the day, what resulted in similar forage intake and animal performance between treatments. On the other hand, it\'s possible that moving animals at afternoon brought more comfort to the animals when compared with moving at sunrise, as they had to graze for a shorter period and had more time to do other activities. (AU) | |
| FAPESP's process: | 12/03121-0 - Effects of diurnal variation in pasture nutritive value and the defoliation start time on animal performance |
| Grantee: | Fábio Cortez Leite de Oliveira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |