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Supplementation with natural sources of lipids and protected lipids in the pre-conditioning and feedlot of cattle: reactivity, animal stress and levels of cortisol

Grant number: 12/07025-6
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2012
Effective date (End): December 31, 2012
Field of knowledge:Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
Principal Investigator:Cyntia Ludovico Martins
Grantee:Carolina Floret da Costa
Home Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The objective of this study is to evaluate the effects of adding sources of natural lipids and protected in the diet of feedlot Nelore in plasma cortisol and influence on reactivity and animal stress. 120 cattle will be used, male, unneutered, Nelore (380kg), coming from system from grazing conditions. The experiment will be completely randomized design with repeated measures, consisting of three diets characterizing the treatments: (Control) without an additional source of fat, (GDESP) with a source of natural lipid-based co-products of cotton, and (GPROT) protected with a lipid source rich in polyunsaturated fatty acids. The study will be divided into two phases: pre-feedlot and feedlot. In the first phase (pre-feedlot, 30 days before shipping), the animals are kept under grazing on supplemental basis of grains with or without addition of a lipid source according to the treatment. Blood samples will be collected prior to shipment of animals (day 0) for evaluation of immune responses. After transport to the feedlot (second phase), are again collected blood samples at days 1, 3, 7 and 14. The animals are kept in 24 stalls with five cattle per pen (10m ² and 1m trough per animal), and each treatment will consist of eight bays, which will be considered the experimental units for this phase of the study. Will be kept the same treatments of the first stage, food supply with twice daily (8h and 15h). The feedlot will be in a period of adaptation (14 days) and finishing. The animals will be slaughtered in commercial abattoir when they reach body weight above 490 kg and subcutaneous fat of at least 4 mm