VALDIR CHIOGNA JUNIOR

AUTHOR: VALDIR CHIOGNA JUNIOR

TITLE: RUMEN PROTECTED METHIONINE SUPPLEMENTATION ON PERFORMANCE OF HIGH PRODUCTION DAIRY COWS

ADVISOR:  Prof. Dr. Edgar Alain Collao Saenz

DEFENSE DATE: 12/10/2018

ABSTRACT: Increasing methionine availability in dairy cow diets during early lactation may increase performance and lead to healthy benefits. The objective of this experiment was to determine the effect of supplementing rumen protected methionine (RPMet) on lactating cows performance from the beginning to the first half of lactation. Seventy-six cows were blocked into two randomized groups by milk yield and days in milk. Supplemented RPMet was added to the treatment diet (SM) to achieve a LYS:MET ratio of 3:1 in metabolizable protein (MP). The duration of the experiment was 12 weeks, including 2 weeks of covariate and 10 weeks experimental period. Milk samples were collected every two weeks and analyzed for milk components. MET supplementation increased milk yield (41.7 vs. 40.1 kg/d; P = 0.03), ECM (41 vs. 38 kg/d; P < 0.01), milk protein percentage (3.14 vs. 2.17%; P < 0.01), milk protein yield (1.30 vs. 1.19 kg/d; P < 0.01), milk casein percentage (2.39 vs. 2.28%; P < 0.01), milk fat yield (1.42 vs. 1.29 kg/d; P = 0.02), total solids yield (5.01 vs. 4.75 kg/d; P = 0.05) and showed a tendency for higher milk fat percentage (3.41 vs. 3.21%; P = 0.06). The control group had greater milk lactose percentage (4.61 vs. 4.54%; P = 0.03) and a tendency for greater BCS (3.4 vs. 3.3; P = 0.08). There was no effect for DMI, milk lactose yield, total solids percentage, MUN and SCC. The RPMet supplementation effects suggests that common diets used in Brazil for high producing cows can be improved if balanced by amino acids, notably when LYS:MET ratio is adjusted according to NRC recommendation, being an option to upgrade dairy cow efficiency.