Milk stability and composition of cows fed anionic diet

Author(s)

Cristian Marlon de Magalhães Rodrigues Martins

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2014-12-16

Examining board members

Marcos Veiga dos Santos; Enrico Lippi Ortolani; Arlindo Saran Netto

• Advisor: Marcos Veiga dos Santos

Abstract

The present study aimed to evaluate the effect of dietary cation-anion difference (DCAD) on: (a) concentrations of casein subunits, whey proteins, ionic calcium, and milk ethanol and heat stability at 140º C; (b) digestive, renal and blood metabolism of dairy cows. Sixteen Holstein cows, with 158 ± 52 days in milk, were distributed in 4 contemporary 4 x 4 Latin Square design, with four periods of 21 days and 4 treatments. The experimental treatments consisted in 4 levels of dietary cation-anion difference (DCAD): +290; +192; +98 e -71 mEq/kg DM. In the present study, dry matter intake, the concentration of short chain fat acids (SCFA) and ruminal pH, and the NDF total apparent digestibility increased according to DCAD increases. Similarly, fat-corrected milk and fat, lactose and total milk solids content were linearly increased by 13.52, 8.78, 2.5 and 2.6%, respectively, according to DCAD increases from -71 to 290 mEq/kg DM; while crude protein and casein content were linearly reduced by 4.83 and 4.49%, respectively. In addition, blood concentration of HCO3-, o pH of blood, and urinary excretion of Na and K increased according to DCAD, which reduced the blood concentrations of cations (Na, K and ionic Ca) and, consequently, the milk concentrations of ionic Ca. As a result of reduction of ionic Ca concentration, the milk ethanol and heat stability at 140º C linearly increased with DCAD [Y = 74.87 (SE = 0.87) + 0.01174 (SE = 0.0025) × DCAD (mEq/kg DM) and Y = 3.95 (SE = 1.02) + 0.01234 (SE = 0.0032) × DCAD (mEq/Kg DM), respectively]. Thus, it may be concluded that DCAD increases the productive performance of lactating dairy cows and, additionally, increases the relative capacity of milk proteins to resist the coagulation at alcohol test and during heat treatment at 140º C. (AU)

• FAPESP's process: 12/22165-9 - Composition and stability of milk of cows fed anionic diet
• Grantee: Cristian Marlon de Magalhães Rodrigues Martins
• Support Opportunities: Scholarships in Brazil - Master