Nutritional factors that change lactating performance and milk stability, and sensorial and rheological characteristics of unstable milk

Author(s)

Cristian Marlon de Magalhães Rodrigues Martins

• Document type: Doctoral Thesis
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2019-02-22

Examining board members

Marcos Veiga dos Santos; Vivian Fischer; Carlos Augusto Fernandes de Oliveira; Francisco Palma Rennó; Geraldo Tadeu dos Santos

• Advisor: Marcos Veiga dos Santos

Abstract

The goals of present study were to evaluate the effect of: 1) RDP:RUP ratio and corn processing on digestive metabolism, lactating performance and milk stability; 2) inclusion of buffering/alkalinizing (BA) and partial replacement of ground corn (GC) with citrus pulp (CP) pellets on digestive metabolism, lactating performance and milk stability; 3) Milk ethanol stability (MES) on resistance of pasteurization processing, sensorial perceptions and rheological properties during shelf life. In order to attend the aims of this study, it was organized into 3 trial. In trial 1, 20 Holstein cows were distributed in a Latin Square design with 5 contemporaneous squares, 4 periods of 21 d and 4 treatments in a factorial arrangement of treatments 2 × 2: factor 1 Corn processing (GC or steam flaked - SF); factor 2 RDP:RUP ratio (High: 107 g RDP/kg DM and 51 g RUP/kg DM or Low: 95 g RDP/kg DM and 63 g RUP/kg DM). In trial 2, 16 Holstein cows were distributed in a Latin Square design with 4 contemporaneous squares, 4 periods of 21 d and 4 treatments in a factorial arrangement of treatments 2 x 2: factor 1 was the partial or not replacement of GC with CP pellets; and factor 2 was the inclusion or not of BA (sodium bicarbonate associate with magnesium oxide). In both trials, 14 d out of 21 d were used for diet adaptation and the last 7 d for sampling. In trial 3, it was used 22 Holstein cows distributed in a randomized block design, where they were distributed into 2 treatments: 1) Control Positive cation-anion balance; 2) Instability induction anionic diet. For milk pasteurization, 3 animals from each group were selected in order to make 2 subgroups according to stability at ethanol test: Instable: 72 and Control: 80%. The results of trial 1 showed interaction between RDP:RUP ratio and corn processing on DMI (P = 0.007), milk yield (MY; P = 0,042), milk coagulation time (HCT) at 140º C (P = 0,029). When cows were fed with GC, the DMI, MY and HCT increased for low RDP:RUP ratio compared to high RDP:RUP ratio, and when the starch source were SF corn there was no effect of RDP:RUP ratio on these outcomes. The milk stability at ethanol increased with low RDP:RUP ratio, 11 independently of corn processing. In another hand, SF corn increased DM and starch digestibility and productivity efficiency. In the trial 2, the inclusion of BA and partial replacement of GC with CP did not change production and milk stability at ethanol test, although the inclusion of CP reduced DMI and showed tendency of reduction of milk heat stability at 140º C. The partial replacement of GC with CP increased the intake of low (<1.18 mm) and intermediated (> 8mm and < 19mm) particles, and reduced water intake, while diets without citrus pulp and without BA reduced the urinary pH, but not the milk concentration of ionic calcium. In the trial 3, the using of anionic diet decreased the urinary pH (from 8 to 5.8), but did no change the milk stability. Milk with high (control 80%) and low ( 72%) MES resisted the pasteurization without forming clots, and, additionally, milk viscosity was the same for both groups during 21 d and 42 d of storage. For sensorial analysis, there was a tendency of unstable milk show more preference of flavor in relation to control group. Thus, the effects of ruminal and blood acidification on milk stability were not observed in our study, and milk with ethanol stability 72% can be processed without negative effect on sensorial and rheological properties in relation to milk stable at ethanol 80%. (AU)

• FAPESP's process: 15/03942-2 - Milk stability during thermal processing of pasteurization and UHT (Ultra High Temperature)
• Grantee: Cristian Marlon de Magalhães Rodrigues Martins
• Support Opportunities: Scholarships in Brazil - Doctorate