Levels of concentrate with or without inert fat for lactating dairy cows grazing tropical pastures

Author(s)

Fernanda Lopes Macedo

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2012-03-09

Examining board members

Flavio Augusto Portela Santos; Alexandre Mendonça Pedroso; Fernanda Cipriano Rocha

• Advisor: Flavio Augusto Portela Santos

Abstract

Levels of supplementation for grazing cows have been studied with the objective to determine the best relationship between amount and source of supplements and milk production and composition. The inclusion of fat sources in the supplement may improve energy intake to achieve the requirements of lactating dairy cows. In this study were evaluated two levels of supplementation (1 kg of concentrate for every 2.5 or 5.0 kg of milk produced) with or without 250 g of inert fat (GI) (1:2.5; 1:2.5G; 1:5; 1:5G) for dairy cows grazing elephant grass during the summer, for 90 days. Twentytwo cows (Holstein x Jersey) producing at the beginning of the trial 20.9 ± 2.22 kg of milk and with 132 ± 60 days in milk were used. They were assigned to randomized blocks according to number of lactation (primiparous or multiparous), days in milk and milk production. A 2x2 factorial arrangement was adopted. Feeding 1 kg of concentrate for every 2.5 kg of milk, decreased grazing time and forage intake (P< 0,05), increased the yield of milk and of milk solids (P< 0,05), decreased MUN (P< 0,05), increased microbial yield (P< 0,05) and decreased plasma NEFA (P< 0,05). Supplementing calcium soaps of fatty acids from soybean oil, combined with the high dose of concentrate, had negative effect on milk yield (P< 0,05), on milk fat content and on yield of milk solids (P< 0,05). Fat supplementation did not decrease plasma NEFA (P> 0,05). The negative effects of fat supplementation were not observed when cows were fed the low concentrate level (P> 0,05). The content of unsaturated fatty acids in milk fat was increased with fat supplementation (P< 0,05). (AU)

• FAPESP's process: 09/13537-7 - Supplementation rate and use of inert fat for lactating dairy cows in tropical grass.
• Grantee: Fernanda Lopes Macedo
• Support Opportunities: Scholarships in Brazil - Master